COMPREHENSIVE INDUSTRY c. DOCUMENT ON …cpcbenvis.nic.in/scanned reports/COMPREHENSIVE... ·...

Comprehensive Industry Document Series (COINDS)

COINDS no12001

COMPREHENSIVE INDUSTRY DOCUMENT ON

ELECTROPLATING INDUSTRIES

CENTRAL POLLUTION CONTROL BOARD MINISTRY OF ENVIRONMENT & FORESTS Website: www.cpcb.nic.in e-mail: [email protected]

MAY2007

c. 0 ·-c:: . (/)

·5 c <D

..Q (.) 0.. (.)

en () CL ()

~

(I) I....... c (J) ()

(/)

> z w

CPCB, 200 Copies, 2007

Published By Dr. B Sengupta, Member Secretary , Central Pollution Control Board, Delhi - 32 Pnnt1ng Supervision & Layout . P.K Mahendru and Anamika Sagar Composing & Laser Typesetting : Suresh Chander Sharma Printed at DSIDC, New -Dellh1

0 c . Cl> ·-> c: Q) ..0 0 Q.. (..)

I -co () c.. 0

-~ ....... c Q) ()

U) -> z w

~~hl ~Ci:tfOT ~"lf ?f OT CJti \ lfRil H~•nl.f •hi illM"-l}

411icf.fUI \!<l H 'i i l<ill

\il. in. "111\ti'<lcn~ . >tl o tt JIUlei

Central Pollution Control Board .A Govt t " 1 (11 J .11s:11

M1111i; lry o l Envrrl)nmenl & Forest~ P11une 2230·1941:! ' 223072:13 J.M. MAUSKAR, 11\S

C'h<111m1n

FOREWORD

The Central Pollution Control Board (CPCB) brings out pubhcations entitled ·compr-!hens1ve Industry Document senes (COINDsr based on the industry-wise studies These reports are intended to cover various aspects of different types of mdustnal units in the country with respect to their number, locations, capacities, types of product usage of raw materials, process adopted, waste mm1m1sation, pollution prevention and control measures. The Minimal National Standards (MINAS) have been evolved as a result of the COINDS. The present report entitled "Comprehensive Industry Document on Electroplating Industries" is latest one being published by the CPCB

The study for the report was conducted on behalf of the CPCB by ENC Consulting Engineers, Gurgaon The help and assistance extended by the State Pollution Control Boards and by various electroplating units during the conduct of this study are gratefully acknowledged Shri T Venugopal, Director, Shn R C Saxena, SEE and Ms L.J. Pavithra AEE, has put keen efforts in preparing this volume under the able guidance of Dr B Sengupta, Member Secretary.

I hope that this report would be useful to the electroplating units, regulatory agencies. consultants and others interested in pollution control in this sector

&~ ~ .----(J.M. Mauskar)

May, 2007

Panvesh Bhawan CB 0 ·Cum-Off1ce Comµ!~x. Ease Ariun Nagar, Delhi 110 032 Fa,. 22304948 / 22307078 email cpcb@alpha nrc m

Webs le ""r .... v..,·: cpcb n1r. m

_.... c: 0 c . en ·-> c (].) ..a 0 a.. u ~

~ .._ CD (.) Q_ (.) -~ ....... c: Q.)

(.)

CJ) -> z w

Chapter l: I. I I l l.2 l 1

C hapter 2: 21 "l ')

") ... -·' 2 .+ ") -__ )

Chapter 3 .. \ .. .., ·' -J.3

Chapter 4 4.1 4.2 4."' 4.4 4.5

C hapter 5 5. I 5.~ 5.3 'A 5.5 5.6 5.7 5.8

Chapter 6 6. l o.2 6.3 6.4

r

Contents

Introduction lntroduct10n Gro\\th of i:tcctroplating. in India Types and Loc:ition of L ruts hJture Pote11ti al

Procc\ses and C hcmicith used Production Proccs-. Prm:e-.s Details Procl.!ss Chemicals Some Theoritic:al Cons1dcrution:-. in I lcctroplating Mass Balance !Or Plating Prnccs'

In-depth Studies in Elcctroplatin~ lndu,try General \nal~ sis of Result~ ~umrnary of Findings

Recovery of Metals (icnernl ril!ratinn and ( "emrifugatinn Evapnrution l :h:ctrol~ llL Reul\ c~ and it:- h:nnomic' Re\ crsc Osmosis

w~1stc Minimisation and treatment to Control Pollution Cit:ncral \\ astc Minimisation and Proc\..SS \llldi tic at inn Bt.'Sl :\' ailablc ·1 cchnolog) 1 B \ T)

\pccitic 0 \ T Approach potential lnitiatl\es and Cost Es11matc:-. \\as Ct: Treatment Option.;; Han1rd0us Waste Rules House Keeping Guidelrnes

Re\ icw of F.'\isting Standard!-> General "luggc .. 1eJ lk\ isions in l-:\i .... ting \t,mdard-. Rccommcn<lation for :'\ lonitorin~ \lf RI.!\ i::.Ld <;.andarJ ~afr Kccpmg or Oat.I

., ')

)

6 8 10 17

27 27 2.7 37

·' lj J<) -!IJ

-l: t~ -. I

49 -l<> 51 )~

5<)

60 6Ci 67

71 71 78 /'}

..

c: u

O'.) (.) a_ 0

~

CD '........ c: Q)

(.)

en > z w

Chapter I

Introduction

I. I Introduction

Hcc\rop\:uing i~ one \\I lhl! ':11 il.!ll\!' ur 'C' crnl \cchnil\UCS nr ~ k\:ll I ini-.hm!! h ,, ·' technique llf dcpo,itinn ol .1 liiw la~cr or one metal on .mother throu~h d~ll'''" Ill pmcc.,s lo imp.1rt '~mm" p1orcr11c-. and :1llributcs. ~uch a-. c:omhi~n prllll"d;1 •11.

cnhanCl"\J 'urlacc hardnc ... ~. lu-.1rc. colour. :ll-sthctk ... vat'uc .1d<lition de. I ll·ctutpl.1t111l! opcrn11un., form parl or la1 J;C .,cak manuf:u:tuai11g plan&~ ( c:.~ . aut11m11halc. l, ck. cngi11ec1111g. am.I numcruu ... other i11uu:-.trics) or rcrfonnc:<.l a.' juh-,;orl h\ ... 111.111 .rnJ° um unih. l'hc~ arc sprcaJ acro:-.s the entire countr) "ith :-,ignilic~nt conccni~-;uion i11 ,c:, cr~I ~tatc-. lilc Punjah. 1 lar) ana. part nf U.P .. Maharashtra. Karn:uakit./\nJhra Pradesh. I umit

'adu and \\'est Bengal. Flcctroplating is considered a major polluting industf') because it discharges toxic materials und hca') mctab through \\U.,tcwatcr (cfllucnts). 11i1 cmi,sillll' nnd so\ id was\..:s \n\o \hi! tcc\(\\1.!n\ c1wirnnmcn\.

In order to regulate 1hc "luali1y of <.11 .... chargc of \\:ash.:\\ah.:r. the Central Pollut11111 l 11111rnl Board. in 1987. C\'Ol\cd Mi111mal "\.;it1u11.1I 'itamlaru (\111'\J \~) lor Jbcharg1.· 111 1.:t"llucn1 under the pm\l..,Hln of' thl.' Fn\'ironmcnt (1'mtl·c111111) '\ct of 1986. ·1 hi-. .... 1.111d:ml 1111\\

requires cumprdll:nsi\'c re\ ii.'\\ in 'ie\\ or the cum .. ·nt hod) of ~mm blgl· 1\;g.11 Jing di charge of pollutants. slalll' of lndusl~. lcdmolng) amJ implc1m:ntation ol •q!ulatn~ mcchani<;m.

1.2 Grcm th of Elcctrophttin~ in India

1.2. I Brief II ii,tury t.l\c. Prei,cn t Scenario

r b:troplt1l111g has a long history 111 lnuia: lil-..c 111:111)' mtlustriul m:ti-. l11c• .. it ~'.11111.'0 111omcn1u111 .iftcr lndcpen<.lc1H.:c tvlodcrn day ch.:ctroplaung startt:d in l.'.111) '"11c' 111 \lumnJ1 "ith dull f\iic:l..d Bright 'lickcl fol lo\\ cu ... unn a.her \lthough olfo:ial ligurc:arc not a\ailable. e~umalc!t (ref 5) indicate that in IQ70. clcctropla1ing inJu-.tr) \\a:con~idcrcd to be in the tune of Rs. 100 millio1 ~ iic::e then. the indu ... tl') lm:!oo gnmn steadil) \\ithout facing an) recession. In 1976. lhl :i~t semi-automatic plant \\a<; ct up in Mumbai. Currenll) there arc more than 600 automatic planb in the count~ . l>urmg .L1..

period 1970-85. the imron restriction regulation in force le<l to high gro\\ th of t '1 '

indU'·>lf) . It is estimated that cl\!ctroplating indu,try is no\\ worth Rs. I 000 crnrc" IR!>. I 0.000 million. see FiJ? 1.1 ). ·r hi"i means that compounded avcra~c annual gnl\\ lh rmi: ,..., about I 6.o01u. l'hc sector cmplo: s about 1.30,000 pcoph: in .1ppmximatcl) 12.000 urgani.1cu units. No s1at1stic:s is a\aalablc for unorgani.1ed imi1s.

m (.) a.. (.) -<J.) ~ ~

c Q)

(.)

(J) -> z w

1.2.2 Types and Location of Units T"he lndustr) 1s \vi<lel) spread out across the LUL11Hr) . \\ l11h: then: an: primaril) t\\(1

'vancuc.;- (i) Primar: l h;er and Original [ quipmcnt (01 ) m.mufocturc:r. \\ho do ckctroplating ns one ol their O\erall manufa1.:!llring activit) and (ii J loh \\11r(.; units." ho do uni) plating for .i large' ariet) or components ror hoth Jo111e:-.11e anJ e:\pnrt purpnsc. Ccrrnin states ha\'e lar!:'.e number or u1111-; eoncentratcJ in "ome to\\ n-; uL1t.'S. such as \ndhra l'raJcsh I l:derabad Ddh1 (1tqar::11- ·\hmcJahad I Ian ana- I andabau Karnataka- Bangalore Mahara'\hlra - Mumbai. Pune. Nashik Punjab - I uJhiana Tamil l\adu - Chcnnai. Madurai Utta1 Pradesh - NOi D/\

It is difficult to find out the distrihulion of production hclwecn the nrg1mi1cd anu "mal l scale I tin: I unorgani1ed sector. Howe\ er. judging b\ the rnnsumrtinn nl' chemicals and additive-; 11 is estimated that about 18.000 Ions arl.! consurrn.:d h) orga1111cu scLtllr. \\htk tin) and unorganrLcd ~cc tor consumes about I 0.000 tons. Thl.!rdorc. ,1ppro\1111:.itcl: 36 °" or the i11duo;;try is contributed hy the unorgani1cd sector.

c ()

c: (}) .> c Q) .c () Cl. {.)

co () a.. ()

~

Q) '....... c Q) ()

Cl)

> z w

rie: I. I (;nm th of l:kctrnplatin;! lndu'fr) in India

3000

2500 II) Q) ... 2000 0 ... 1500 u Ill 1000 er:

500

0 1970 1980 1990 2002 2012 2015 2030

Year

Fi2. l.2: Shan· of Chemical' ;1' inpuh lo ckctroplatin:.!

Additives 28%

Precious metals

47%

Nonprcc1ous metals

25%

..... -. c (.)

c . (/)

> c <D

..Q (.) a. u

en 0 (L

0 -~ ~

c Cl)

0 Cf) -> z w

...

<>I tlw '"'H:r.al \.1ric11c' ol I k"·1111pl.1t111g. l'rcc111L" ~k1.1ls «<1 ·d. SilH·r ct<.'.J 1~·l)uirc :111 111p111 ot R' 4 7" cn1n:-;. "hcrca' other 111c1al t :\ i. Cr. Cu. Z ' " ..:tc.) r'-'llllirc :!-' aorc' - .111 prllll'IP~ll h.11h dlClllh:at, uni) I he !>har\.' or :1ddith Cs ,, l..' ... t1mnl\.'d :ti lb.~5ll \. r.•n.'' hl'l' f'i:.! 1.2 ). I hcrdnn.· \:1lu1."-\\i "'· prc.:mus metal ol.'cup~ h1ghc'\t position hu1 imJustn.11 cl lorl und c:mplo~ mcnt '' i'"'· con\ l.'11111111.al < r. :--:i and In pla1ing occup1c~ high1..•,1 p1i...iti1111. <>I' this sc:t.:tor. ~-\\h1..•clcr i11du:.l1) fhul11 hi-c)Clc :11nl motori/ed units -\l.'1111t"''"· 111opcd' and 1111Horh1)..c,) j.., tlu: ... inglc l:1rg1.''' ll'l'rs. lm.lia b nnc of the largc ... 1 producer' of hi-L')Clcs in the \\orlJ. pr11Jucin~ ,1h11u1 lX.000 uni1 ... pc1 da) \1<1tori/cd units pnxluctHlll is c ... timatcd I 5.0011 pl.'r d.t) :.111d " likd) to gro\\ 'c1) 1:1st.

1.J Furur~ Poll'111ia l

I lw1"' ill\' W\ era I ''-'~'h,r,. "hich .Ill' at !11\\ I.I.'~ IHI\\ hut 11:1' high ~nm th pn1en1ial One 111 1111, '' L'kl'lronil· 111d11 ... 1n .111d pr111h:d ..:ire 111 ho.111.h \\hich i-. uni~ \\orlh lh. 10 crnrc .... hu1 ha' ht1gl' potcn11al "nun<l j, ti r..' :111tn11wli\l· i 11Ju-;11·) h· llh :! :and ·1 \\ hL't:lc::r' 1.

pankularl) rl:uing ''" .\H" '" ilarl) "ith l.uropc um.I '\111 h 1\mcrica graJuall~ llllJlOsing \Cr~ '\tlll'I Cll\ lrOllllll. lt.tl 1cgulaliu11. 1lw1c \\tlUld Ot. lllllrL' Ollls\lUrcinl! or comp1111c11t-. from industrialised L'Ol11ll1ic-. 10 lnJia l'hirdl). Indian chcmic<1I product-. arc .. 1ill lhc cheapest anJ of rcrngn11cd quulrl} l'hc c\port m:tivi ty. '"hich rs 110\\ only 20 crnfl.'' .1 ) car. 1.:.111 .1d11c\ c I00° o gru" th rJlc 11\lT the nc.\I Len } e.rrs. lhc org.mic inll'fntl·Jiatc~ u,cJ in ~. and Zn plming an: al'o \\cll-c~tablished items for c:-.port. Con 1dcnng 1hn1 a l'onccrtcJ effort j, umkrwkcn b) the induslf). lh\.' projech:d gnm th m1c '' uppro:-.:. 6°0. "hi.=h \\ill not he dinicuh to achic\C. l'hus. 1hc dcctroplating mdthtf) can a quire a ,jzc of R ..... 2.000 crorc:-. in 1h1.: )Car 2012 and L':m su,1am 1hj, rntc until :!015.

.....-.. c ·-() ·-c . (/) ·-> c Q) .0 0 Cl. u

m () a.. ()

-~

+J c Q)

0 en -> z w

C hapter 2

Proccs~l" & C hcmiC.l l' llscd

2.1 r rnclud ion Pr(l(:t''

I lh: ha,h.' dcl·tmplating s) sk·m ultl'''t' l'I : I) \ plating hJth lilkd "i1h \\.lll'r 1.'.rnll:aininµ a 'mall amount 111° :1l·id 1•1 .ill..uli .uJdcJ hl

i111p11l\ 1.· ii.. c11nd11l'ti\ it) . I hu' bath' "'~·d liH pl.111 ng ,11 c l'llhl'I :tl·td ba:h Pr alJ...al11w • 11 Ii

2) \11 .1110Jc (po,ili\c ckllrmkl cithll tlw pl:t11tl!.. mctal 111 .111 i1ll·11 1 • .'kl' lrodc: this'' l'\P'-'nth:d ''"tile proct:'' guc ... 011 .111d ll'pk111 ... h1.:d pc1 1udH.:all)

3) \ c:1lhodc (n1:g.il1\lc dcclrPUl') - the i1c111 111 he pl.111..·d thl''I.! lU11lw1.'1lhc1 111111µ in ... ick till' hath or pl,tu:J 111 .i barrel. "h1ch b m1.111:d 'I"" I) 10 111.1i..c the pl.11i11g mJll'rt.tl Jcpositc<l c\cnl)

l J,uall). the hath j..; containl.!d in mctul i:ont:um:r. lim:<l "1th add ;ill..:1li resistant mcmh1:mc e.g. fl\l' sheet to mal..1.· it insulatcu from electric circuit.

Tht! application of direct ckcrric current annss the li:..ith ,nlutiPll c:1u,1.·, the migration of • Posithd) charged pan1dt.~ (anions) to\\urd-. the lll'gathc ckctrmlc (cathodl'\ and • Ncg:ui,·el~ charged p..:.rt11. cs (cations) toward' the po,ithc dcctrn<ll..'' (;.modl·)

I he procc,,es arc oltcn exothermic and this leads tn etc' atcd hmh tcmp<.>raturc compared 10 the amhil'.nt h:mpl'.rnturc. The prnccs' cnicicn..:) lkpcnd lo som1.· dq!rCl' on the • ( 'onccntration or acid and alkali in the :\(llution

• l'cmperature and • Voltage appl icd acru ... s the dccllHk' The Item to he coated 1s immersed in the hath -.olution ~is th1.: cathode and tl11. coating substance (the anode). I lowc\er. if an mcrt ch.:ctrndc I'> u-.c<l. the coating sub-.1ancc \\ould be the metal salts in liquid fo rm added to the solution. I he mewl sails subscqucnll) dissociate into anions and cations. which tlu:n deposit onto 1hc t1cms lo b1.: plated.

Ap..irt from the bath chemicals and anode material. other chemical agents arc used. such

l!:I.

• Brightcnt!r • Weller • Booster • Purifier These chemical agenb help to pro' idc desired attrihutc,, uch a' hright surface lini,h. improved nnd C\Cll metal dcpo!'ition. ucpolari1.ation. fa-.tcr reaction clc etc I he chcmicab 'ary according to Lht! process 'arianh and limshing rcqum:mcnb for ,1

particular metal plating.

5

-. c: 0 c . en ·-> c (1) ..c 0 0..

en 0 o_ 0

~ ......... c (1.)

0 Cf) -> z w

• B~ :ind 1:11 ge. mo:st metal tini.,hing operation ... t~ pi<."all) ill\ nlvc 3 Ill -t pnnl.'.ipal "111~ tcfh or pr1~e~' upcrations. \\ hich ma~ occur singl) or in comhmation ·1 !ic -._.!re·

• 'urfocc preparation • Prc-trl·atmcnt • Plating ,md • 1't1.,1-11 ca11ncn1

2. :! . I 'url:acc Preparation I Prc- lrca1mc111

I hl· purpo ... e j, to prcparl.' am d1::·111 the items li11 plating. l'hc aeth it1c' 111\nhcJ arc a:. 'ho\\11 in T:ihlc 2.1 bdn"

T:1hk 2. t

S urface Preparation & Pn~- trcatmcnl

~lain Acth it' t--

_ ~- tc I 0 cralion Function Stu fore I Bufli11g \n n1llhcning 111 surl~tl."l'

l'rl' >aratmn ~i.; .licncics h' 'Sl.'r.t iin!.! ~~~;--~~~~-~~- ~~-+~~~~~~~--''--~-L->~..._~~1

l're-trl.·atmcnl "' Cknni11g Rcnm,~il of llil. grease. din . ..;eak'

.. ·'

finm thi.· surl:K<: of tlw iti:m-; u-;111g -;nlH·nts ( ol h:n i:hlorm.llcd

ll\ drni:arbllth J

Jkmm al nl adherent 'ohcnt alkali <irid u .. ing \\aler

L.__ ~ -~~~~~~~~~~~~~~~~~-~~~~-l_l<_l,_'~

LL! l>lating

... -c::: ()

c (/)

> c: (1) ..c <.,) 0... (.,)

~

~ -en (.) a... (.)

Cf)

In 1h1.: pl.Hing procc''· the itcm' tn he pl:lll'J an~ pl.u:..:d a'S thl! cath(ldc 1n a11 ckc1r,>I) lie > hath containing metal ... alh .. \ I lircct ( ·um:nt j.., pa,,t·J 1 al hl\\ 'nllagcl through the z del.'.lrc,lylc. \\ lwrcin fll\:t~1I ion' arc platcd <'lllo thc <.".llhod..:. I lw 1t'n' in ,0Jut1011 Jrl. W replc111'Shcd b)

• I h<: di"11luti1m ,,r md.tl fr,,m tlu: ,mn<k (the plating 'Sllh,1<t11cl.·) or • lnrrc.1,111g the metal ,,i11 t•one<:nllJtion ,,(the 'uluti1111 (\\hen u,111g an

mcrl c ket 1 ode) or hu l h

\lte1 pl:.t1111g. tht· pl.1ted lli.'llh are nn<>i:<l ''ith \\,Itel . \11c1 ri11.;i11g th<: iteni-- ari.· d11ed elllwr 111>1 mal .11r dr~ ing 111 ho1 air dr) ing or 111 .111 "' 1..·11. I he opcr,uion:-. ol pl.Hing. tra11,fl:r

from pl31ing lo rinsing t.mk' (in "hich hath solution clrot!-tllfl oct:urs) un<l rin.;ing can l"lllwr he 111a11u<1I or m1.·d1:.111i1cd (~utom.111"· ).

(1

2.2.J 1•0,1-crca lmc11t

1os1 Hcctmplating operations are completed h~ the plating opcrnllon. if the item ... do no l

requm: posl-ln:atmcnt (as in the case of Double l\:ickcl Chrome Plating I I he purpo"e of the post-treatment i :

• to enhance the ph~ sical appcarjncc of the item • 111 imprm c the corro::.ion rcsi')tan.:c nf lhc item • for Jccnrati\'c purposes

I here arc :1 'aricd number of post-treatments: • con' crsion coat111gs • chrom~1ting

• phosphating • passi' ating • metal colourinl:! and . -• St'aling

A brief description of thc ... c are gh en in 1hc follcm mg parngraph"

(a) Cum l'r,ion Coatin~: Comersion coating b pru\ i<led to pTl.!\Cnt t•ono .. inn .md lo limit lhc gnmth or ... :.ilt:-.. \\ hrch mn) form due to corrosion. ~Ian) hea\) mctnls. such u~ Chromium. Vanadium. ~lol) bdcnum and Tung-.1en in their l11gh Htlt.:ncc stntcs ha' e the abilit) to pre\ cnl uclt corrosion. The most common I~ used com cr..,inn coating i) he:'\a\'aknt chromium u-;ing '\oluhle chroma1c sail such ,1s Pola..,sium di-<.:fm,nwte. calkJ chromate com c1 sinn coating or chromating.

(h) l'hosplrntin ~

l'his IS a f)l'OCCSS 01' coaling a metal Slllltll'l: (llSLl:\ ll ) g<tlV:tlll/Cd iron & Sled . • J111m111il1111 de.) \\ ith a layer of inso luble 1m:t,1I phusplwri:s h) lrl·a1111g tl \\ ith an .1ud1L phnsphJlL' containing solution. /int.:. iron .md m.111g.111csc phosphute coatings an.: lOlllllHHl nt \\ h1t.:h Linc Phosphate is the 1110,t rn11111111nl) used sail. Phn-.ph1.1ting is d11m: II' ,111 c'\ccll~nl ha-;e for recc1\ ing painls. oib und cnld-tim11i11g luhrkant..;

(c) Sl'a l i n~

\nodil· coating arc usuall~ JX'TOU":> anJ arc cJlcd and arc scnkd to impro\e coll>Ur durnbiht) and rc-.i;;;rnncc h' ~laming and corrosion. Sc.iling. is done b) in11ner ... ion in hot \\atcr during \\hich ar,._rphous alumin:i ~urfacc of1he anodic \."Oaling is comcned to <."r) lallinc alpha alumina h~dratc. \\hich incrca. c the \Olumc and clo. c the port>.

(d) ~kra l Colourin~

In thi" process a colour 1s f'lrmeJ on the surface of metal . I h1:, is quite an old proccs. \\hkh is not much used at pre~cnt. I IO\\l'\Cr. \lurninium l'Olouring i' in \oguc

7

c ()

c: (/) ·:; c Q) .c 0 Cl. u

co () a.. ()

~

Q) "'+J

c Q) ()

Cf)

> z w

- .....

\ \\IJi.: \arii.:t) of chcmicab and :-.uh:-.lJllLC'> .arc ll'>L'J, dL'fll.!nd111g upon thi.: :-.urf.tcc pmpcrtiC'> or lhe nhjcct~ lo he i:kCll'\lrl<lll.:J platillg •111U lini\htng ri.:4uin.!llll!lll ll" \\Lil .1~ ihc 1echnulog) / fac1lit~ ullcrc<l h~ the plater~ . It is \c~ dillicult lo prnvh.k full dctaib of all thu-.c: u~cd: because there urc more than 11ni: cornmorl) used proCC!>S for certain metals. 1 lcncc :1 gcncrnl description "ill be cm:cn:J in this \LLlmn. I\ sum ma•) is gl\ en in Annc'ltre J . ,,,_ c . :!.J. I Hra'' l'latinj! (.)

c: In brn'" pla1i11g. gcm.•rnll) a c~anidi.: hath j.; u-.~·J . "hich compril-i:-.. l\1(('N). NuC'\ .!Q Zn(( · h and N:1: C< >; l"hc <mode io; non-cunsuming conductor. >

c Cl)

.2.3 . .2 Bron1e l'httinJ:! ..c (.)

Br 11.·i: hcing a combination of Copper and I in. the bath sails comprise Cu< CN).. NaC~. fr NJ \riO~ and NaOH. Bath is therefore c~~midc alkaline. 1\nodc i!> n<m-consumint:; ~ couJuctor li~c iu bra>' plating. ~

.2.3.3 Cadmium Phi li o~ _.,

C.1J1·1ium platin!,! abn uses :in alkalinL t)Jnidc hath comprising bath salh liJ...c '\!1.1( N. Na CO 1 and Na OJ I.

(() ( d(l ,,_ 0

2.3A Chromium Platine

c... 0 -Cl) '

There an: 'anauon' or Chromium pl.Hing l>rt.l111a~ chrPnh.'. har<l chrome and hri!!hl c chrome. Ci1..·ncr.i •. i:hromic add n.uL '" u~cJ 1.. .. ::pn-.1r;g h.1th suits liJ...1..· 11:( "1< >1• 11 "< > Cl) anJ Nal . Nur j, u-.cd to imprm c the conductivil" 111" the dcctroh tc. 0 . . .

CJ) -> 2.3.S Copper l'latinJ!

Thrci.:1" t~pcs of bath arc u cd- (1) C~anidc Copper hath. (ii) Copper p)mphn,phJtc hath ~ and tij'."i \cid Copper bath \s the name suggest-.. the bath in thi: third j, aciJ11... \\h1k th1.. llr-.1 l\\O arc ;1lkalinc Buth constituents for Cyanide Copper bath arc : ('u(CN) NaC'\J. N::._ < O .nd NaOI f. r or C oppcr pyropho~phatc <.. t. P 0, . NI I.a 011 and 1-- .P .!< > 1 Jr1.. U'>cd . In acid copper procc,~. a mix olTuSO. and 11 _ \0. is used.

2.J.(, (;old Platini,t

l\•ur pwcesscs arc available - (i) Alkulim: C)anide lu-.ing K1\uCCNh. 1--C\:. KOi i and " "C () ( · 1 'L·utr.i! (i,1ld h.tth lusin:: K ,\u(C'\:) . f...( I Jl'd K::! l IPO, I. ,\1..1J C~unidc lu~ing f... •\u(l Nb . KCI unJ Citnc l\ciJI. It mu\ he noted that the main constituent in all

s

th1c1.· ptt\\.'C,,c, 1" Po1.1-.-.1um <"'Id l ~.1111Jc. I he 111ur1h i-. I la'h ( iold pr.ice" ll'-111~ \u< I nnd I It 'I.

2.3. i Nickl'I Pia tine

'I hrc1.·11' procc"s\!s arc Cl1mmonly u-.ctl - (i) \\all ... Nid,cl huth I u-.111g a mi\ ol ' '-,()

Ni Cl~. 11 ..._o :md I !;BO: ). l ii) Nickd Sulphamalt.: Bath I u-.ing Ni( 11,so . b. 11'. ! "' > ). (iii) \\ 110J" Nickel Bath I u-.ing N1CI= and I ICI 1. one ol th~ pmn:-.-..:-. u ... c C~ a .. JJ1..

2.3.H Palladium

Being u prcciou-. mctal. u:-.agc i-. -.omc,:\\ h~11 n:stnctcd ( hil) one procc'' using .1c1d hath 1s common!) u-.cd . Ball' con"titucnt~ :m::P<l< ·1= • :\I I 1CI and I ICI. ~11111cl111H:-. P.:illaJium· Nickel plating '" us1.:d in "hich Pall.iJ1um :111J Nickel i ... dcpo"ih.:d in one hath. In this procc ... s. bath cu1blllut:•1h arc: PJ(~l I :H~< >.?b !\ ickcl 'ulpltJmate and NI l.~011.

2.3.9 Plarinum

I \\o processes arc a\ ailatllc : (i) Alkalim: Platinum :met tii) 1\1."iJ Platinum. In thc limncr. 11,fltCI,.. (NI 11 )JPO~and NI 11011. In add Plutmum. ti.1th co11-.111uc11h .m: I l :Pl(~O:F'0 1

anJ I l ~S< >J

2.3. 10 IUuuJium

Onl) one prt11.:c"' u"ing at.:id hath l.'(1111pri-.i11g Rl111di111n "11lph.111..· :11 I "' lhmk· at.:id 1s

used.

2.3.11 "'iih er

I \\ll procc ... -.c., an: a\'ailahlc, both ti:-ing \1hc1 l ).1111dc \il,cr ( )~111i1.k htith comp1i-.cs l\.\g(C N) . I\.( 1\/amJ l\. ,(.'0, \cid hath uses 1\. 1\L•(( l\J)~ l\-.i 111'01 .111J II P0 1.

2.J. 12 Tiu

There .ire lhrcc pn)cc.,scs - (i) \lkalin1.: (ii) i\ddi1. 11ml Ciiil I lu\lroho1.111.. . 111 alkaline l"in pwn'.S!'t prim.1p.1I chc1111cal u-.cd arc \odium \tJ1rn:llc :md ( 'uw.111.. c..;, ·<la: ·1 n \uiphatc u-.cs \tannous "iulphah.: and Sulphun1. .\1..1tl . In 1111 I h1ornh11ratc pro1..c..,s. l "hcm cab u"cd :m: ~nmF~>.. I IBF.i. ll ;BO ,and I tr.

2.3.IJ Zinc

There arc three procc .... -.c.., a\atlahlc (tJ 1\1..·id <"~~111iJc. (it) 1\ll.;alinc l')aniJc anJ (iii) Alkaline C)ani<lc Free. Acid C)a11id1.· u:.cs a hath 1.'.0111prising Zn<'I · ~Cl. :\.11 1('1 an<l ll;BO, In J\lkali111..· C~anidc. hath c111t....titm:nt-. :ir1..· . /n('~. NaCN. ~aOl I and \:a. CO .. In th-.: 1\ll\alinc Cyani<lc Free (J\CI 1 pr1l\:c". h.11h 1..·h1.·mkal-. :in: rathc1 -.,1111pkr. /nl > .md NaOl I. l'h1..· latter is gaining popularit) a" u C) ~midc lrcc procc~;:, .

,,

~

c: u c . en > c (1) .0 u a.. u

en 0 a.. 0

-~ ~

c (1)

0 (j) -> z UJ

2.3. 1.t ,\nodb.in2

\nodising i!> main!~ u-.ed a;) a prc-clc::ming opcr.11inn hut -.omctimc~ u~l!d as a metal tini hing opcraticn rn ... •iodising. the obj1.--ct i~ m~u.k l\nodc. 'o that impuri1i~;; am.I other metal' ur1.: rcnh1\t.'J ')ulphuric .11.:id is mainl: u. cu ,1, ckctrnl: tc in the bath.

l.3.15 l'ho,phatiog

Phosph:mng is carried out mostl~ as post trcatm1.·nt or plating. I h)\\c\l~r. it i~ often tbcu us u11Jcrcoat to rcceh l! paint 11n metal. .Bath co11st1ttu:nts <m.: i'.inc-L'ak1um Phosphall· and N:i1 PO~ .

2.3. lCt C hromating

I lw. 1s .il;;;o a po't ln:atmcnt to pl:111ng. lbth cniht11t11:111s ,in: ,,1·< r< >1 .111d '\:a~('( J

2.J.17 l:tchin!!

I h1-. is u-.cd ns a pre-treatment to pln11ng .md gcncrJll) U'-C acidic hath I crrn; l'hlorid· .. etchant ( f'crric Chloride and I ICI). Acid etchant ( mi\ of Cu( I· I !Cl and 11 1' . I \lllllllllliacal etchant. a mix or J\mmonium Chlor idc. ,\11111111niu111 I l:drn\iUI.'. UI J '\11Jiu1 l

11) pl1chloritc) i!> tbcd. t\ sum mar: ,,r chcmk:il-; is gi,cn in Ta hie J . .!.

2.-t Some 1 hcorctica l Con~illcratium in EkctroplatinJ!

l ~ ll:clroplaling i" a complex dicmicul prnc1:'s ;111d 11 is ni.:11h1.•1 p11s,ible nor in11 . .:11di:tl In Jcal \\Ith Lhc theoretical aspl!LlS Ill this lrC.lllSC . I fll\\C\CI. <.:1.:1Utill ha'>IL C011SIULratHlll'

anJ 111tniduct1nns \\Oukl help 111 undcrslL\11J111g the pn>cL·s,l!s and factors rnllucnci1w thcm. lhcsc would be dealt with bncll~ i11 th1 .uh-wc1in11.

2.-t.1 ( aku lation of coatin~, lhid,nc..,s, C\fHMJl'l' tin1L' and cutrcnt dcn'>i~

FaraJny's la\\s form 1hc basis of finding imponanl utluel\ h>llO\\ing arc the parnmctcr exprcs~cd in unit<> customa~ in electroplating:

l:.c-1 Ekc'""lc11emical equi' ralcnt. in g.ah I· Plail!d arc.i 111 dm: I - Current·. k·tsil\. in amp i Current intensit; in amp Jm: t - L:..xposure time in minute::. 11 - Current cn~cienc: in % d Thid .. ne'\s < f metal deposit. in microns Ht) y lkns1l~ . , ; cm~ V - Volume of thl.! deposited metal G \\'eight Llf the deposited metal

10

0 c . (/) ·-> c <V

...0 0 0.. 0

en u a.. u Q) 1.~

c Q)

u Cl) -> z UJ

Far.ida) ·s firs1 la\\ in the form G ·~ <..) applks to a rc.iction \\hich proceed' at 100% current cffkit·nc) . Becau~c this i~ nommll) not the ca.;c. the current cfficicnc ~ 11 mu ... r he introduced into the equation. \\'e obtain

( i f-... Otl I 00 (I) Introducing time in minute' and currem densit~ in amp dm2

\\C obtain G Let i f 111 / 6000 gram:. ( 2)

The coating thicknc's d y_ (cm:) inµ i:- then: F (dm-)

d I 00\ 1111cm1h lu) r

~uhsti1u1ing \I <i. \\1...' nhtain y

d -1J100 micrnn-. (µ)

yr

(3)

\ccording to thi ·formula. \\C obtain the C<.lating 1hickncss on the plated surface F from the dcpositcd "eight G. ror G \\C can introduce Eq.(2) and obtair~

or

d- I 00 l~t i l·tn (p)

6000yF

d- L~!.:!!1 <µ >

(5)

<iO ·( I· (61

I .sing 1hi' equation. 1IK i.:urrcn1 dcn<>it) required 10 11btain th~: desirt·d coaling thickness. in a givt·11 ti1111...· t i-.·

1 Ml cl y (:unp/dm2)

t\nd the limi.: n.:quin:d. for a given current clen~it~. i-. : 1- M1 d y1min)

l ~1 i11

(7)

(8)

If instead ol' the \'.ll;1ting thicl.:nes::.. the \\dght dero itcd is required. the formulae corresponding to equations (7) and (8) are ohtain1..-i:I from Eq. {2):

1 6000 Ci (amp elm~) (9)

1.:.:1 F tT\ 1-\nd

6000 lj (mm, (10)

l:Ct Fi Tl l'hcsc formulae appl~ equally to cathodic d~position and anodic dissolution or metal. I he ,.1lul.' l'fEr1arc ghcn in Table 2.2.

11

...-...... c (.)

c: (f)

·5 c Q) .c () Q. (.)

;: ~ -ro () a.. ()

~

Q) "...... c: Q) ()

Cf)

> z w

onl) to th\.' small h)drogcn ion!) and not to the large (I ICr~O;] ·onsists of basic chromium (Ill) chromate. Cr (Ol l)CrO.: .

aonc; I his co:uin!!

In order to ohtain dcposition of metallic chromium. the clectrol) tc mlht contain a cenain quantity nr some other ~u.:id. This loosens the cathn~k lilm to -.uch an cxh.:nt through 1.:omplc:-; limnation that chromium Jcpnsition is rende1c<l poss1hk The cflcct of the '-,ulphmic acid present in a chromium acid ckl·trul) te n.: ·ults fmm the foct that it forms .11. eusil) :.nluhlc com pie:-; \\ ith trivalent chromium. und hcnc.:c tends to pre' em the formation of a cathock film.

2A.3 Co-depo ... ition of fo rt."ign o;u b~tuncc'

t\11 ekctml) ll' compnnc111..;. thu'i not onl) th-: l'ations but also the anic1n-; and uncharged :-uhstanccs and p.1rtkularl) or::;~mic nnJ inorganic colloid.-. can he includeJ in thl.' cmtmdic <lepo .... it in varying <.JU::tnticy. <krcmJing on the dcpo:-itiLHl l·ondition ..... Onl) 111

\Cl) ra1c case" i' a mcml depo~it\.!J on till· cathode in a highl) pure form Co.1ting:-; from t1.:chni1.:al dectrol) tt!s nearly ah\ a~:- c.:ontain foreign suh tnncl.'s. Ttw foreign sub..,1anc1.: .... arri\C <P the cathoJc 11\\ing to diffusion and C1ll1\c.:Ction. Onl~ \\ith positi\t:I) charged .... ub .... 1 • .um.~.., i .... clt!c1rieal tran .. p<lrt irl\ohcd. Most fim:ign ..,ub:stanct!S arc ph~ sicall~ hound k the cuthode ':>Url~1l·c h) adsorption. und also partl) (and rn1m: 'Strong!)) b) c.:hcmi orption. Elcc1ro .. rntic binding can uni) 1.iccur ''hen suitahlc charge" arc present. The adsorpti' c nature of the bond is indicated b) the im:rea"c in the quantit~ of inclusit)ns '' ith increase in the cunct:ntratiun of the foreign suhstancc up lo a limit. tht.: saturation limil of the surface. and b~ the relation hip:- 1'ct\\CCn incorporation nnd molccular si7t.'. th\.' h:mpcralurl.' and the ndsorption cnpacil~ . The valid it~ of the Freundlich ad orption ic;othcrms has hccn dcmon:-.tnucd for c;ome foreign substances.

The direct co Jerosition or inorganic ion~ is rclntivel) slight. When ~uch anions urc found in thl'. dcp1hit in appreciahlt: quantiti.- .... the\ ~irc ll'\Uall) "P;tringh '\olubk dec()mpn"1L1on pmJuLh of t1lhcr. often organic compm111lk l'hc 111curporation u1 \ulphur ill 11IC~l·I and 11thc1 ml.!1,1 1 depo~it~ b dul' tu thc presence or ~11lpl1111 1..·011ta111ing cnmpounds "uch a" thiosulpuhate. th1omca. "ullon;11e-.. ct<.: 111 the clcctml) 11..·.

·1 he incorporated !'.>Ulphidc j, formed through h) drnl) sis of the <iddcJ Sulphur c<1mpoum.b or b) clcctrol) te reduc1ion of quadrhalcnt Sulphur contained in the ::tdd111on agent:.. Other foreign sub:-tnnccs incorporatt:d in 1hc dcp<NI arc oflcn furmed 111 lhc cathodic diffusion In) c "Kcwisc 1hri 'u:;r lil-c\\ isc through chcmica1 reactions llr ~athodic reduction. i\1 c;,.,'";'lotter and II ~cl !nclknmc)cr found ma.\imum oxide cont~nt<:: of 3.5'!-o in zinc dcpo~1b trom' n zim.: sulphate clcctrol) tc I he maximum m:idc \.1tntcnt of ;-me coatings dcpo~itcd from n cyanide electrolyte is gcn\.'nill) onl) 3"~. \\ h1lc that of def>\)Sits from an acid 7inc hath is considerubly lo\\ Cr. In metals dcpusitl·cl from a t:~anide

dcctrol~ te is sometimes possihle analytically to de1c1..·1 metal cymtidc. "h1ch doe<:: nol sh:m from inclu'\1011s of cb.:trol) tc It j-. produced in the cuthoJc film. ad"1rhcJ b~ the catlwJc tmd then i111.."01pnra1ed inw the deposit. Sihe1 ,lt,:p11si1.; ln'm J l.'~:111ide ~·k1.trol~ te. pnlduced under suituhle \\orking c1111ditions. can contain upto 0.22 \\l'l£h1 % of

13

,.._, c (.) ·-c: . en ·-> c <D

..0 0 0.. (.)

~

~ ...._.. co 0 a.. () -~ ~ c <D 0 en -> z w

c u c:

aJ (.) a_ 0

~

Q) ~ ........ c: Q) ()

en > z w

Table 2.2 Electrochemical equh"alcnts, atomic ''eights, ' a lencic!I, and densities of m etals

important in electroplaling'

M~tal I Valency

Ag I I Au 1 ,___ -Au ...

-'

Cd "') --C0 "') -- - . -Cr ()

- ·- -Cu l -~2 I !:~ ~; wn -- ~

Ni 2 Pb l'J

-l

- -

Pt R'1

·---~

.... II

~11

Zn

' ·' "') -n

Atomic I Weight

I 07.870 196.967 196.967

112.40 58.9332 51.996 63 5.+ . --63.54

.--:\5 ~-n I -l S.::: ~\.-1

207 . 19

-

---106.-H> 195.09 I 02.905 118.69 118.69 65.37

-Dcn~il) (g cm') E::lccrrochcmical Electro I) te at 2011 C equivalent ~1 10.50 4.024 All sil ver baths 19.29 7.3.+8 Cyanide gold bat 19.29 2.4495 Ferro cyaniJc

baths -8.64 I 2.097 All cadmium bal 8 g-; 1.099 All cobalt baths - --

1 0.J23 Chromium baths t-6.95 . -8 .Q} 2.372 Cvanidc COJ?.Per l ~ baths

1 X.93_ · _l _.1_8_6 ______ Acid copper baths 7.~6 1.042 All iron bath-.

... 7.31 ~ l.,:t28 -S.QO 1.095 - - ---11.3..f 3.865 - --- --- -11. 97 I. 984 -----21A5 1 1.819 ~- ---+-- - --

1

1.2797

~:~i')~ , 1.219

12...f4 7.28

7. 13

All indium baths .\II nickel ha1h.;

J All lead baths PallaJ1um bath:.

-\l!_.El<.!_t~um baths

,\II rhodium baths A<.:id 1111 baths Alkal111c !Ill baths 1\l l 1inc baths

17.28

- ---'---1!,1,i.:J Ull lilt: l lltcmational atorn1.: wc1gh1s or I %2

Sour.:c. Rnub. K and K. Mueller, .. , 11ndamanlal!- of I\ lctal lkpl>~1tm11 " (n:f: 8)

2A.2 Electro-deposition of Chromiull)

Chromium occupies a special position '' ith respect to the depo::.ition mechanism. \!though allempts lO chromium from "olution<; of <\llnplc sails pro\ed that chromium

l.'.m1IJ Ix· deposited. for example. from solutions of sails of tri' alenl chromium. the pr..1cticJI solution or thl. c.Jilfo.:ultics imohcd ha-. not )et been achte\'ed. Chromium. 1h.:1di1n:. i-- al\' ays depos1tl.-d from aqueous -.olutions of Chromic acid. These dcctml) lcs Jiffcr 111 ~e\eral rcspe<.:ts from \1thcr plating baths. I lc:re. \\e shall. onl} co1hidcr the Jt.:pt•,1111111 mci.:ham'm ot d1romium from chromic acid elcctrol~tc - this has been the .,uh1L".:L l>f nurncrnus :auJ1cs.

Chrllmium occurs in the hcxa. tri <tnd <fo a lent fo rms \Vhile the [HCrO.d - ion 11n.:Jum111at~s in dilute chromic acid solutions. main!) the lHCr~01J ion is fanned al the LOlh::cntrntions usual in chromium baths. A certain quantity or trivalent chromium iOi S is also pr~sent. If such an aqueous so lution is electrolyLcd, a strong film forms on the cathode, and this prevents the formation of a metallic deposit because it is permeable

12

(.)

c ti) ·-> c Q.) ..0 (.) 0.. , .. \.J

~

~ -en (.) 0.. (.)

-Q.) ,_ ... c: Q)

0 (j)

> z w

cyanide.(e.g .. Table 2.3) Various subslances are intentionally added to lhe electrolytes used in practice in order to innuence the properties of the deposits in certain ways.

Organic additions are particularly widespread. However. not the additives but their decomposition products are often co deposited. Elucidation of the mechanism is thus difficult and relatively few sludies have been carried out. The incorporation of these foreign substances is of special importance for the technological properties.

The chemil:al comrosition of electrodeposited coatings is also clearly affected b1 incorporation of foreign substances. l'hus, a measurable difference in lhe equilibrium resl p<.Hemial as compared with that of the pure metal can often be found. The metal containing foreign substances usually has the less noble potential. The tarnishing rate is ofkn increased, and chemical reagents also attack the metal more vigorously. Thus, for example. the induction period for the attack of dilute nitric acid on si lver is shortened and sometimes reduced to zero. On the 01her hand, the lower corrosion resistance or bright nicl-.el as compared with mat nickel is not due to lhe general affect or the foreign incorporations in bright nickel coatings, but to the specific effect of' their Su lphur content.

2.4.4 Deposition of bright metals

The production of bright metal deposits is a relatively young branch or ekclroplating technology. The development of brightening electrolyte, which is credited to M Schlot1er. began around 1930, ·when bright nickel coatings could for the tirst time be produced by adding organic compounds to simple nickel electrolytes. Although the deposition of' bright metal coatings has made enonnou..'> progress since then. the chemical nd energetic processes involved in it have not yet been fully elucidated. The development or brightening ad<litivc::i and brightening electrolytes has been carried out on an empirical basis .

H fischer distinguished two types of brightness. depending on the origin: reproduced and intrinsic brightness. Reproduced brightness is formed on a base material with a brighl surfacl:. and the corresponding electrolytes are also termed brighlness preserving electrolytes. The brightness or the support is maintained only when thin coverings are ~ppl1ed and is lost when the thickne'ss of the deposit exceeds certain limits. A bright effect is also achieved by means of the current-reversal technique. The cathodic current phase is maintained until the brightness begins to diminish. During the subsequent anodic phase. the surface is anodically polished. On this bright surface, another coating is deposih::d by the next cathodic phase. T~,is technique can onl y be used ir the electrolyte has a certain anc,dic polishing effect and provided that the anodic phase is short compared '°"ith the cathodic period. Intrinsic brightness is produced by brightening additives bright coatings can be deposited on mat surfaces fron1 b(ightening electrolytes. The hriohtncss is independent or coating thickness and may even increase with it.

14

Table2.3 f.ffcct of foreign suh~tance addition on the properties of electrolytic silHr (from 0.5

'i \~~01 ~olution) and copper (from J M C u~o~ solulion)

--- _ Q_ u_a_n-ti_ry_· --~-D-c-nsit) TSpccific rc1,i!\tanct •H I 'icker~ incorporated G/cm1 room tempcra1ure JO " bardnes~ weight - % I ilcm kp*lnm2

I Pure sih c:Ir I 0.502 1.59 43-100

r -Foreign 'iuh..,tance

c.Jeposil from cvanidc bath ...._.___ - - - -------- - .. ---Glycocoll 0.02 I - 55 Metaphosphoric 0.8i 1 10.260 acid 2.6:' 9 825

citrate .>.:"> -5.8 -

l.Q 300 Q60

r~JOO 157-185 liS

~itric acid J ~-~ 9.214

~----------.-------------- - -l'a1 taric acitl or I 0. 7 - 143 62.h turtrJl\: 1.:! - 175 no ·A;paragin~ l ff.7-- - - ---i-----

17.2 1------ _ J_2_0_7 _____ -j-8_.9_6_6_-t-

1:3oric ac iu I. 6 9. 135 - --

178

5 18 7.958 --Pure copper 8.923 l.7 50-70 Ul:JlOSi t

1.7 Ci lycoco ll 0.0 I () 06 0. 19

I - --· 1.8 -.----

(\ ,_ 70

____ !-__ _ ---i ~ /\1h:t~1phnspho11c: 0 2

acid 0.68 ., ' -·-' !--------!· Citric acid ur 0.67 citrntc 2.3-1

17

1350 '>5.5

~-~ l 2_._6 _______ 8_. _I~-) l_-..--1 :!~JO t\spartic a~id 1.0 2·-Ht

Tartaric acid tar1ra1c

I "' "'.-"'00 I -1 r1 • .J (} - ~\I -

OI 0.4X I -0.49 O.S7 0.97 l.~4

15

~------! 249 275-29CJ

265-263 ~

2 l <)

220 I 249

195-:!78

0 ·-

en () 0. () -Q) ~ ........ c (1)

0 (/)

> z w

--c (.)

c: . (/)

> c: Q) ..c (.) 0.. (.)

~ ~ ~ -a:l

(.) Q. (.)

-~ .._. c: CD

(.)

Cf)

> z w

Source: Raub. 1-. and K \ Tueller ... I undanrnntals of \fetal lkrm~itiori'' (rel 8J rhc umts ··pond" Ip) and ··l..ilopond .. (kp) arc units of for.:e. \\hil't .. gram·· (gl :md "kilogr<1m" (k!-!1 arc unill> of weight

('arbohydrah:s gin~ only a .-.tight brightcnmg effect and ha\c llltk eflt:ct on the trend of' the C<.lthode potential-current dcnsit) curYes. 1 he group of aliphatic compounds 111cluJc, both c;trong and weak brightening agcnh. The lir"l group incrca-;cs p<1lari/alio11 slrnngl), the ~ccond one onl) little or nnt at all \romatic com rounds can .ilso be di\ idcd 111lo Lwo groups \\1th regard to brightening effect. Aromatic am mes gcncrall) Jn not improve brightness apprcciabl) but increase the polarization Other aromatic compounds. particularly those containing Sulphur are strong brightening agent<> •\romati~ and hetcrocyclic sulfoac1d-; arc strong brightener<> and imanahly increa.:;e the pn!Jrizauon .

2AA E,pfa nato ry notes on terms used in distribution of meta l d epos it'> on the cathode

Electro!~ ticall} deposited mcrnl coatings arc not dbtribuhxl uniformly O\cr 1he part sen ing as the cathode. The local thickness difference:- depend on a large numhcr or factor:.. and an: more pronount.:cd whcn lhc prolilc of the pa11 is irregular. ~omclirnes. no llOlH.:c;.1bk dcpositiC'll takes place 111 rct:e<.SCS. the intCrlflr or lube-. ClC.

V1ri<'u-. tcP11~. onen not 'er~ clear!) defined. ha\c been intrn<llll:cd in clcctropbting tcchnolog) 111 an :inempt at charactcritation of the distribution of deposits on the surface of v1mousl) shaped nhjccts.

The Le1111 C:<Jl'l!rin~ pm1·er is used to denote 1hc depth to '"' h1ch metal deposit ion on a certain surface profile takes place. l'he depth or penetration of thL Jcpn,il 111 centimeters into a certain surface rcces..., can be talo.:cn as .i ·nc·1o;;urc of cnvcrinb po\\ er

The term thrcm ing pmrer is ll'\Cd !Cl dcnotr.: the local thid.neo;;s J1 lkrcncl:s in clcc1rol) tiL

coatings on an object. The throwing power or an electrolyte bath is good when the distribution of the deposit is uniform. and poor \vhen it 1s nol unil"orm.

The grcal practical importam.c or thnm ing p<l\\Cr is based on th.: lac!. thal th~ ~u:ility of an clcctrol) tic coating depends great!) on its distrihutil\f\ on the metal to be proh.:Llcd 0-ol the mean thickness of the coating. but 1b minimum 1hicknc"s l1l the ·critical" points is dec1..,ivc. The critical points arc thnsc \\·hich urc suhjcdcd ln particularly inlcns~ mcdmmcal or chemical strcssc" durmg use or \\11ic.:h arc particular!) important for the lunc110ning of the plated pnrt. I he customer mu-.t spcci I~ \\ hich pt>ints arc ·criliL·al" . In man~ cases. 1naximum uniformit) of the dcptlsit di:-.tribution is desirable. i.e. good tlmm ing J'X'' ., ,· ot the clectrol) tc.

The pcrl ''11HgL ralin of the smallest and greatest coating thickness at two particular points or 11, .... ibJ~Cl mn) be used as a measure of the throwing pc)\\cr.

·:\·licrr1u. ''ink Pl \er' is gl\ en b) the difference in deposit tlw .. 1-..ncs~ al l\\O particular point' of a· litmprotilc' (t ll'-. in general. the Jiffcn .. riLes in th1d,nes-. at the grnO\cs and

16

•.

on the .. flat .. surface or the peaks of a surface profile). As 1hc transition from the .. macro·· to the ··micro .. profik is continuous. n 1' 1mpon::mt to kmi\\ the factor:.. "hkh determine the definition of these tcn11s.

With sullicicnt convection in the electrolyte. no effcctiH~ differences in the thickn:~s ol the cathodic diffusion la) er are present '' ithin the range of tlic macro-thn.J\\ ing po\\t:r. The cause of lhc macroscopic 'ariation is the ··primal')' current distribution··. Inadequate corwcctiortat 1hc micro 1e,~1. hm\e\er. can ghe rise &o dTt'Cli\•e local diffcn:n('C!> in the thid:ncs~ of tt1c cathodic diffusion la~ er \\ ithin the range of the micro -thro\\ mg p<)\\Cr.

This implies that the n1ass transport of the charged particles determines the di,l·har~c \ 'primary current dbtributinn .. ;s not prc,cnt \\ i1hin the range of the micro-thnm mg pt>\\Cr. The bon.h:rlinc bct\\et!n macro nnd micrn-thnming plmcr i:; thl' point \\hen: diffusion hccomes the dceisl\c fac.tor for the suppl~ of dmrgcd t:<1mplcxc:i.

B~ /e,·ellmg is meant a decrc:i...;e in the initinl urfacc roughnc~s ol' a 11.11 t throu~h dcpnsi1ion of the clcc1rolytic coming. Le\ citing i not idcnucal \\uh micro-tlmm in~ ptmcr. Under certain conditions. hm\e\er. le\cling occurs \\ithm thc mngc o f the mi~mthrn\ .. ing pcm er.

rhc percentage ratio of the coating thickne ... , on the pm tile gromc-. and the r cak .... (or th1..· ··nae· :.urfocc) can nbo he taken as a mca~urc of the micro-thn\\\ ing P''''cr .1ml kH·lm~ nn II particular prolilc.

2. '.\ \l a" Ha hmcc fo r Plating Procc"

1\:-. mcntiom:J in the forc;;oing. Lhc plating pmcc:-.., could either 1mohc nno'-l ic dis ... 11lu111rn (e.g .. Nickel. Zinl-. etc) or dcctrol~lie lfj..,,olutiun (Chnimit· .1cidl 111 ~ i tl11..·r 1..·a e. i1 ;., po .. ..,ihlc lO calculatl.! sL01chil'metric am11llnl of met~1l dt·pos11io11 on c.1th11Jc In rcalit). nn re.i~llnn '" 100% complete. neither the a"'\t1lllptin11' \t1l1d in Faracl.1~ · .., l~I\'" ~11c \\holl\. ach1e\ahlc l>uc tn lhc"e rqsoth m11n: input in tilt• fi11m 111' 1111.."l:d :1r~· 11ccLkd. Second ly man) sub~tunccs arc added lt) c11ht111l.c. lllllUi I\ und alll'I the 111LWI tkpu1.,itio11 pmccss and rrnpertll.!S or deposited mctalo;; Whik -.nmc nl' tlK'"e d11 nol dir~l ti: l.l"l' pan 111 mass lranslcr. others undergo a \ariel) ol 1.:0111plc.\ pr<1cc-.-.c likc chcmis11rpl111 1. Cll

deposition a.; ti:\ ides and various olhcr fot 11,.;, (i1..•111..·rall) lore1g11 suhsinnccs ;mi\ c at the cathotk ll\\ing 10 diffi.1sion and wmcc1io11 and \er: li11lc due lo dc.:tml~l ic transportation. 1\s foreign suhstancc'. use C'f both i11organic nncl orgn1m: addition .... jc;

\\idc pn:ad. For C'\:amplc. the induction period forthc att.ick of dilu11..· 111tnc .1c1d on -.ih1..·r is !>lmrtened and :.(lmctime!> reduced to zero On th1.• other humJ. the lm\1..·r corn,....ion re:.istance of bright nickel n..; rnmpared \\ ith null nickel ii; not c1·uc to the general :.i fli:ct of the foreign incorpoiatinns in hright nickel coutin~s. hut to the -;pccifo.: cflect of 1hear Sulphur content.

1 hus. in m:m) case , not the additive;; but their dccomposiuon product!\ ::irl' often co deposited. 1:.lucidation of the mechanhm i thus dillicult and rclali\ cl) fc\\ stud1e-... h:l\ e he~" carried out.

17

--.. c ·-0 c

"' > c: Q.) ..c u a.. (.)

~ ~ ~ ..._

co 0 a_ 0 -Q)

l.-t-J

c Q)

0 Cf) -> z w

c: (.)

c: rJ)

·s: c: <l) .0 (.) 0.. t)

ro l) ()_ l)

~

Q) :i...

..f..J

c: (].) l) Cf)

> z w

In the case of dcpo<,,ition of hright metal coatings. enonnous progress has hccn achic\ t!d since their incepLion. bl1l Lhe chemical and energetic processes 1mol\ed in it han: nol yt!I been l'ul ly elucidated The development of brightening addilh e'i and brigh tening electrnl~ Les hl.l!> been cCtrrictl out on an empirical ba~is.

In' IC\\ 11f these constraints, Lhc empirical natun: <1nd enormously large number of foreig.-n substances and substances enhancing the hath electro!) It's. the atll'lllph.:d m 1s~ balance.: \\Ould he restm:Le<l Lo pnnc1pal constituents onl). f\\n e\amrle~ \\oulJ he dealt \\Ith· '\.ickd and l hromium. It ~hould al5o be remembered that apart from dcctrul)tic inpuh and metal deposition on substances {as cathode 1 a:- outputs. lnssc~ are to he considered Herc again. ln,ses are prindp;ill~ due to

1i1 Jragmns and rinse The ma"s (.iml related vult11nctric) rate5 derend l>ll the tecniquc and handling prac1ices and \'ary O\er a \\Ide rang.L' \\ell managed and properl) handled plant!> ma) still get to achieve lower than l millil1m: per -;q. ft. while a range: of' I LO 2 mlli lilrcs per sq.11 ol rlalcd area or approximately I lo 2 liLrcs per I 00 sq m. ol plated area is commonly cncounccrcd.

(ii) rcjecLion nr bath when It.!\ cl of impuriucs reach certain prc.:-di.:1crm111cd limits

(iii) In addiuon. there are C\ aporation losses Imm hath hut this is usually of m.iJ alkali mi'\ts and vapours. The mas'> cmhston rates of metal:;; or metallic salts in vapour~ and mists are not ~et \\di dtKumcntcJ. it \\ould ~e ratha small compareJ to oLhcr l\\U lossc!\.

2.5. 1 '.'iickel Pla ling

First. a calculation of Ni mcLal dcposiLion is made usmg r:ara<la) ·..,la\\: t:d 1.0995 'Y = 8.90

-I amp /dm1

11 = 90 (%) 1 = :rn min ( ranee I '5 to .30 min) f" = I 00 sq. rn. - l 0.000 dm!

(i -= 1.0995 x 4 x I 0.000 x 20 x 90

6.000 l3 I Q-l I? • 0 ] "' I k - 1.c., . .) .... ·g per sq.m

ror unit F. \\ h1ch carr~ out 14.00.000 sq. rt or plaling pi.:r year. LhC) would 11L'CU 17.174 kg. In n.:ulity the) spenJ 1700 to 1800 kg uf t'-11 anode pc1 monthJ..c .. 1750 '\ 12 kg rer year on average. Sn. actual conversion is 17.174/ (1750 :-. 12) 8~.211 11. I he inJuslr) an:ragc is RS to 90 'Yc,. 1 hcrdorc. 15 If' I 011

'0 nl Ni anoJc is lo-;V\\astcd.

Cst11natc of dragout loss 1s calculated on the basis ol \\ans Nickd hath l:nns11tuems . N1ckd "iulphatc = :!40gil Nickel Chlorid~ ~ 40g I

I~

Boric acid 30 g/I

Total quantit) lost in a y~ar 1~ calculated a 1.0 litre t'f bath -.olution pl.T I 00 -.4 m 'Jickcl \ulphatc <'1SO .. 711.: 0) -- ~ 1.226 kg. '-icl,.cl ( hloridc (:--.iCI: 6H~O) 5.::!~ kg Bone al'id (I hB03) 3.903 kg

I IO\\l.!\er. the enttre draJ,Wllt is not lost. First. the) an.: rcC)clcd to hath: second. the unit ma) resort to metal recover) In case or unit I . \\here Ni recover) is pracuccd. these tigurc':> reduce to 600. I 01 .ind 96 kg respect I\ cl) a.., net loss through \\ aste\\ al er Part of Horic acid ma) he lost through C\ aporat1on. hccau'c the bath tcmpaature i:-. around :.rn C •

and hath is agitated b) bltm 11 air. ·1 he mass balance diagram is sho" n in Fi~. 2.1.

2.S.2 Chrome Plafin~

I fen: <il<>o. a calculat1011 of Cr metal depos111011 1s made first using h1rada) ·s "'": Ec:t 0 113

- 6.95 <>.5 amp /dm 2

- 15 (%) n t

F - 3 min C t\\eragc fordccorall\l duomcl

I 00 sq. m. I 0,000 <lm

G = 0.323 x 9.5 \: 10.000 \: 3 ~ 15 : 130 g . ') "I ,. c 6.ooo 1.c .. __ J g per sq.m o r

Or corrcspondinl.!ly 2 . .30f0.52 = 4.42 g or anhydrous 1..hromic acid per 'q '11. of platcJ area nf ckcoraci"c chrome

l 's111g this figure rn l lnit H. plating arcu of 10 lakh sq. m. ,,·nulJ need 4420 kg. In <lccorati\e plating. only ahout I 0°'o of the chromic arn.J added to the hath is <li.:pusite<l on ohjecb ~ plaling. Unless rcco\ercd. the balance 9(l% \\OUld lead to hlssc,. Also. there i~ dragmn losses.

Lst1mate or drag\)llt loss IS cakulatcJ Oil the h<tsi-. or Chwmc hath con-.titlll:nts : Chromic acid - 280 320 g,11 Sulphurit.: acid 2.1 - 2 5 g/I

Total quantit) lost ill a )1.!0r is calculated a, l.O l1tre of hath solution per 100 sq.m.

Chromic acid Sulphuric acid

= 3000 kg - n kg

I lo"e' er. the cnure drag.out is not lost. First. cuntc111 or dragout tank is often n.:t.:)Clcd tn plating bath: second. the t1111l ma) resort to<. hromium recover) Pan of sulphuric acid

19

c 0 c (/) ·s: c <J) .0 (..) Q. 0

I -ca 0 a.. () -Q) ,_

+J

c Q) ()

Cl)

> z w

l ..J 0

Nl -an odo 21,000 kg

600 kg NI -sulphato

NLJ -chloride -102kl'>-v--~,~---.-----M-

'

SemiBright

•

NI-deposition on Objects

17, 174 kg

.. Spunt NI -nnodo

3826 kg

Dragout loss Drag out - - :...-,.

NIS04 31 ,226 kg - Tank Tri- --+ Bright

NiCl2 5,204 kg . ,,

I Wator

Unreacted NI 3826 kg

•

Ni-chloride s102 ke Rogeneratlon - I Unit Nt·S04

Ni-sulphate 30,626 kg ~ - Nl ·C l2 Losses ~

Rinse Tanks

~

600 kg

102 kg

'-------- Rogonoratlon chemicals I acids

Fig 2.1 · Ni-Plating Mass Balance Diagram

(Showing metal recovery)

--

.......... c ()

c: lf) ·::; c: Q)

..0 () 0... ()

OJ CJ a.. CJ Q) I.... -c (1)

CJ (/)

> z w

ma) he lost thrnugh e\aporation. ·1 he mass balanc.:c diagram for a plant doing dl.'eoratin: <;r-plating (a 1 IO lakh ~q. m. i~ shown 111 Fig. 2.2.

2.5.3 Si lver Plating

Fir..;t. a Lak,. jtion of Ag metal deposition i.; made using Farada) ·s la'' : r -t.024

y I 0.50

T)

l F

() 4 amr /elm:'. l)() (%)

- 80 min ( ranl!e 75 to 90 min) ... ., I 00 !-oq. rn. - I 0.000 um-

G =c -t024 ~ U 4 :-.: 10.000 x 80 x 99

6.000 19115.2'=' i.e., 0.193 kg r~r sq.m

For unll X. "hii:h carr) out approximate!) I XOO "ll m .. or siln:r plating per year. the) \\Ould need 347.4 kg. In reality the~ spend '511 to 360 i-.1! of t\g anodc _ncr ~r on average So nctunl comcrsion i' 97.8%. ThL· industi: a\'cr.igc is 99 to l)lJ.5 'o .

"I ht: re· ort:. l .5 to I% of Ag i~ losL \\ astcd.

I s1ima1t: ol dragout Ins~ rs calculated on the ha-;1s of Pnt:1c..sium "illn:r C)anidt" bath con-;titucntc..: I rce ~iln:r 30g/1 I· rce C ~ an ide Potassium Carhonalc

30g .,

150 to 160 g/1

Toi.JI ttuantity lost in a :ear i!-o t.:alculatcd a I .fl litre ~,r bath solution per I OU sq.m Free Silver 540 g I· rec Cyunidi.: - 540 g K~C01 .., 2790 g

1 lo\\C\Cr. the entire dmgout 1s not lost. First. tht:) ire rt:L~clcd to hath: second. the unit rc .. orts to metal rccO\cry. In ca..;c lif unit X. \\hl. ·l. \!,. ·el.O\Cr~ is practised. tl1l. l')lJ of sihcr cyanide and potassium c~anidl. is 3000 !:- \nee the individual quantitii.:' <Jre 11111 kmmn. the com:spondi1r: \\eight°'" I \g(C'\!) _ I :s •N6 g hascd on 80 5°" · ihcr ~onh.:nt a I 00' 'o purity 11 rcco\ er~ ,., wn,i<l.:rcc.I ,,., 99 1~0. 5.4 g of / \!;:- 1., 11..:1 l!>S~ through \\i.l'>IL'\\'ater l hi.: ma~~ 11,1la11ce ciiagrnm 1-; "hm\ll 111 Fig. 2.3.

2.5A /inc Platin!,!

In alkalin\! non-c~anidc (c~:midc fr.:c) proct:ss. a cakulation or Zn metal dl.'po,itinn i:... made using Farada~ ·s La\\ :

l.:..r 1.21 t) '( 7. 13

21

,--.., c: (.)

c en "> c Q)

..0 (.) Q. (.)

~

~ ..._.

aJ () a.. ()

~

(1) "+.I

c Q) ()

(/)

> z w

1-.. I _,

Deposition -+ on Objects

4420 kg

6

r ros h Cr-acid Rlnso 3 ,000 k . Plating Bath Drag~ut Drag o ut Tank . Rinse r

~ Tonk .

,000 kg r . loss Tank #1

0

. 3,000 kg #2

, j~

Unre acted W ater

Chro mic acid 36 .580 kg I

Reg eneratio n ~ Regen . Chemicals

- Unit -- -Chro m ic acid 38,000 kg

r

Waste 1580 kg

Notes 1. Figures relate to plant doint 10s sq.m. p.a. 2. Waste with regeneration= 1580 kg 3. Waste without regeneration= 36,580 to 39,580 kgs

Fig 2.2 · Chromium Plating Mass Balance Diagram

(Showing metal recovery)

co () CL ()

Q) ....... ...... c Q) ()

(/)

> z w

~

Ag Deposition

on Objects : 19.3 kg

Sliver Anode 19.72 ko...,.. _ _... __

Silver Dragout loss Potassium S liver

Cyanide

~

-------i_N Bath Free Ag 5409

..._,,_ __ _. Free C N 540 g

I K2CO~ 2790 9

C N 432 g

Ag recovered

~ted Ag 0 .42 kg

R egeneration

Ag 534 6 9

Tank CN 432 g

Oragout Ag 5 .4 g ------Tank CN 108 g

K,co~ 2790 g (as products

o f dissociation

K O H, co~. H)

In powder fonn Silvor loss

9459 9 .6 g

Reaction products

o f K , CO, NOTE : Figures relate to

1 00 sq. m . of plating

Fig 2.3 · Mass Balance Diagram of Silver Plating

m (.) a.. (.)

~ -c (l)

(.)

(f)

> z w

-· c (.) ·-c (/)

> c Q) .0 (,,) a. , .. v

~

~ -ro (.) Q. l)

-~ .._. c: CD

0 Cf)

> z w

= l-' am11s per sq. ft. i.e., J.506 :unp/dm1

= 75 (pcrcenl)

F

(i

-1-0 mm (a' cragc for auto component etc. corresponding LO 12.5 micron thickness) , 100 sq m - 10.000 dm·

l .219:x 1.506" 10.000 .\.40\ 75 6000

= 9179. l g = 0.092 kg per sq. m.

~ow. 1000 sq.n (92.94 sq. m.) plated to 12.S micron is mass eqivalent or 8.2 kg or ln . The t:Orrcsponding ligurc or G I\ 8.55 kg I or \CF process. Linc platers use a range of 8.4 to 8.8 kg In anode com.:sponJing to 12.5 micron thickness cl\ er 1000 sq. Ii.. ( 9::!.9 sq. m.) I his mean~ that the actual cumcrsion m:i~ \ary from lJ8 % Hl

94°' ror a \\ell-organised plater. the avcrag~· is u:-uall~ 98%. Therefore about ~ % Zn ts lost I \\astt!d. Estimate <'f drag-nut lus:- b calculated on thl: hru;b of bath constituents @ 1.0 litre of bath c;,olution per I 00 ~q. m. :

r ree Zn· 18 g "iaOH. 190 g Organic •\dditi\ e: IS ml.

MaJur part or the free Zn is recovered (about 90%) as hydroxides in the waste tn.:atmcnl Lmil and retrieved as sludge (non-h<l!ardous). rl1c ~l u<lgc can be reused to manufacture tine chloride. zinc sulphate etc. T'hc two other processes. namely, /\cid I.inc and Cyanide Zinc, have higher cum:nt erficicncics e.g., acid zinc - 95% average (range : 92 lo 98%) and cyanide 1i11c 80°/ii (range : 60 to 85%). But they have unfavourubk distribution ratios owing lo reduced throwing power. This means that more metal 1s d1.:posncd in high current density areas as compared to lo"' current dcnsit} areas In other \\Orcls. l(.>r objects with high portmn of high and medium current dcnc;ll) areas, more metal has to be deposited to ensure minimum thid.ncss specified. \\hich 1s usuall) the areas of lo\\ currelll dcnsily . Corresponding!). the total amount of metal Jcpos1tcd ,., ill be higher in these l\\O proces-.cs for same object as compared to \CF process. Ob\ iousl:, the quantities of \\astc<l melal and bath solulions (acids an<l/or c~arudc") arc higher in chose processes.

2.5.5 f'oppf"r Plating

Copper plating is used in man) situations, particularly a.o;: undercoat to recei\'C preciou~ metal coating. There are both c)an1de and non-l.yanide process. Acid Coppt:r is one of the 'er) common!) used procesc;e'). ror this proces~. a calculation of Cu metal deposition is made using Farada~ 's La\\ :

24

F

(1

- 1.186 8.93 I 0 amps per sq n I .C •• I Jl76 amp. dm: I 00 (percent) 55 min (a' erage corresponding 111 I \ ' m1cru11 thickness)

= I 00 sq. m = 10.000 dm~

= 186 x 1.076 x I 0.000 :-. 55 >.. I 00 6000

= 11697.9gper100 sq. m. = 0.1169.7 k~ per sq. m.

2 Now. I 00 sq. m. plated to l 3.3 micron is mass cqivalent or 11 .88 1..g or Cu. The corresponding figure of G is 11. 70 kg. So. the actual com crsion procc-;, 1s about 98 5% or more. Therefore about I 5 °··o cu n.:main" in ~oluuon or \\<Isled I •\limatc or Jrag-out loss is calculated on the basi-; of hath constitt11:n1-; r,; I .CJ litre of hath !>Olution pi!r I 00 sq. m

Drag-nut losses: CuSO. ll:SO ..

220 g 70 g

Major part of Cu is recove red (about 90%) as hydrn:-.idcs 111 the \\aste treatment unit anJ retrieved as sludge (non-hazardous). The mass balance is sho"n 111 Fig.2..t

25

c ()

c.: . (J)

·:; c CJ) .c 0 Cl. \.)

co (..) (l_ (..)

-~

-4.J

c Cl)

(..)

Cl)

> z w

,J f r

H2504 2.925

cuso .. 5.265

C u A n ode 11 .88 kg

Objects

.·

kg

kg

. r

• • • Pl at i n g Ri nse Tank . Dragout . Tank

Ta n k # 1

I I I I I l ___ ___ .. ___ J I I I I I I I I L----+ Product of Dissociation

cuso .. 5 045 kg

H2so. 2 .sss kg

Free Cu 0 .182 kg

r

CuS04 0.22 kg

Rinse

- Ta nk

#2

•

:: P lated Objects

Cu : 11.698 kg

Fig 2 .4 · Mass Balance Diagra m of Cu Plating

Acid Copp er Process

c ()

c

co 0 Cl. 0 (]) b. -c (])

0 (/)

> z w

Chapter 3

ln-dl'pth '" tudie in Electroplating Industry

J.l (;encr.Jl

In or<kr to carr) out .111 in-ckpth ~auJ) ura \arict) of ch:ctroplatmg units. cnn 1dcrution~ \\l'I\.' gi\l'll tu \ari1111-. factor:- ..... uch a" - -.i1c nfunit' (limall. 111l'di11111 Hml Ltr<'l'). location of indll'ilr\ ( j l oll'IO:O.S the lOUlltr~ ). l~ r1..• of J1latcrs ( j C , p1l!11arj l!1>Cl"S. \\ho lllLllHll~ll'tlll"i.''- prmhtl'l"i Ill \\ht ch elecln>J1li.lll11g is lllll' nr the lll<llltlltlCllll lllg processes. sul.h as bi rydcs. mntori1cu two-\\ heelers. san itarv lhtun:s. etc and job work units. who l'l'lldcr plutt111.! w1vtl'l'' Lo components manulacll11Td b) others). pl.11111g 11wtcriab (Linc. ( hrnmi um--.c\ er .i I \ .u-ict 1c-.. N id.el. < npper l\r,1'' Prcl ious materials ( ~ii\ er. Gold 1.:tc. ) and h:l'hn1>h'g~ used. a' ~omc 111 thi.:m pr<ictil'c i111prO\cJ methods.

I he result'i of the in-depth stud) ha\C' 01..'Cn anal) ~·d '' ith re pcct to the folio'' ing : • I )pc of units • Qual1t) of R:m ( l ntrcatcd) \\'n-stC\\;itcr • Quall!) o f I rcatcJ \\a!>lC\\akr • \\mer l -.c and Co::-t o f\\ a .... tC\\Jlt.'r I ~Jtmc:nt • Air I 1111,,1011 't~11u ... • Nni ... c h111~s11111 Statu ...

I h\'.' ... \.' cm.· di~l.'ll Sl'U in the suh~cqu('nt r~1ragrnph'i.

3.2.1 T)'l>t! of llnih

In the 1.a'c or I b.;trorla ting, large units (\\ilh puid-up capital ahnvc Rs. 5 crnrc) are virtuall) non·l'\istcnt. I hen.~ arc ·rrima0 us1:rs'. "ho manuhtLtun:.., l'Olllplctc producls. such u' hicycll.':-;. motoriscJ l\\O-\\hcckrs and autl"110bllcs (4-\\hcdcrs). in \\hich ckclr<•plnti11g is ollL" of the manufal'luring opcrationo;. These units cun also be c.:alled ' integrated unit s" On the other hand. it is more comcnknt ll' dassil) these units on the basis of tumO\crs. In such a case. da-.sifo:ation can be easier. im.!5pcctivc of the fac1 \\hcthl·r the) arc primary users. oubourccd units of OE manufacturers or job-\\ork unit . Tahll· 3.1 shO\\S the distribution of unit'i in the in-depth stud) .

T2hll· 3.1: Di,tribution of l' nit' in the Stull~

.--~-----------------------------G ro'' Annual Tu rn-ovc_r ___ P_c_r_c_c_n_t _o_f_T_o_t_:t_l __ _.. ______ ._t_J n.1!IP.t.:_' __ _ > I crorc 5-t I .arl!e "

"'- -----t' <her 50 lakhs hut under 1 14 Medium I

crorc , Bclo\1. 50 lakhs I 32 Small I

27

I

-c ()

c CJ)

> c: Q) ..c u a.

co 0 a.. 0 Q) ~

+J

c Q)

(_)

Cf)

> z w

-· c ()

c . (/)

> c: (1) .0 (.) Cl. (.)

(]'.) (_) a.. (_)

-(1) !........ c (1) ()

Cu11-.c4Ul"nll). all primal) U'\Cf' and tntcgmtcd units 1:111 in tin.· lur~c cah:~Or) : thc'c urnt' gl·ncrJll) tcnd to ha\ c 1111..-chani1cd :rnd .nllt'nrntic handling and hath o~r.tti.ln . I hr) :m: morc lil.cl) to ha\ e fume Ctlllcctiun ') .. 1cm too or ,m: in a po'iition 10 do 'n .

• l.2.2 Qualin of Raw (IJntn•:th.·d) \\ ~•-.ll'W•llcr

Tiu: characteristic qualit) of rJ\\ (untreated \\nstC\\ntcr ohscn cd during in-Jcpth stud) '' ,ummansed in Table 3.2 for 'nriou' t) pc-; of plat in!!.. I he fol km mg oh,cn auon-.. mil) bc noted I \:i · Cr platin~.

..,

... ·'

In \!i-Cr plating. \\aslc\\ah.~r. pl Ii~ u uall) aciJil" 1111ea11 pll ocing 2.'J. IS · is not .1

l'llll\'.cm hut ·1 D"'i 1s high (mcn11 nt 2754 mg I: In scH.:ral units it \\il!S notk~'tl that ~ilkalim: rinsl.'. \\~te \\.lier arc mixed \\ith main \\astC\\31Cr from plating hath and rnt-.1ng tank:.. In such cases. pH incrca-.e-. 10 near normal 7.-t I. f"hb pmt:tkc unnccc.,sanl) r~quirc~ more acid tn Ile .uJdcd to lo,,a the pll to around :! ' lnr rl.'.ducuon of ( r(\11) tu {"r( 111 ).

Both t r(VI) and l r (TNal) un.· con~iJcrahl) high at 6.99 and 167.7 mg.ii . Other 111l't,1t ... ( '\:i lJ 1.2 mg I and Ph :! X) also n:quirc alkalin~ precipitation. < >ii,\ (H\;,1,c anti "I lHal Re::;idu:il Chlorine arc not u matter of concern. he.:au:-c their ,,1lucs .ire "i1h1n pct mis..;ihle limits ol" cl llucnt for Jis1:h;ug1..·.

11.irtl Chrome plating

!\ lthnugh 1 hcrl.' is 110 funclumcntal dillcrc11ce in pl:tl i11g \\ ith r1..':>pcct to l h1 omc pla1ing. t l11..· ''astcwmcr indil·:w.:d 'er) high 1 l>S :rnd l"r concentrations: thi:> is p.utl) due to 1hc fact th:.tl rin:-l' \\~11c1 \ 11lw11c is 1101 as much :1' ob-.crvcd in Jcl.'.11ratiH· clin1111c rla1111g and Ni-C"1 pl:11i11g. 111 nth1.:r \\l!l'ds. Ilic \\U!:ill.:\\LILLI I'> l:lllll'l'lllt:ttcd. ha' in~ 11, 11\\11 aJ\t11ttag1..·s nml d1..,:1dva1llt1gcs. Rcllln\ ul of "I I)~ '" a :>l' I iuu.., 1cq11irc1111..:nt in linal trca1111c11l of' this ~i11d ol'"a-.11.:,\a!l.:r.

Cf) I he \\:t~h:'\\atl'r conlains <\Ubstnn11.il concc111rn11on of Cr and Zn. pl I is ,tll,,almc. > twcau'c thc ~ample ''a dr:I\\ n from the 11cntrali~1t1011 tnnk. C) anidc \\:lS rather lo\\. Z tk·c,m:.c the diluent from C)amclc 0'\1d:t11on 1s tat...cn tu m:utrah~atil111 1a11k I krc tno. W I D:-- j.., high .

.:i /inc Platin!.!

I his 11\ them<''' common plating :1cth it) 1l11oughou1 the coulllr). almost c4ual 111 NiCr plating. I hcrc are four procc'>SC~ \\hich arc in u:..e.

In Ilka/me C :amide Free procc!-.~. 1h.: \\a~lC\\atcr ha:.. alkaline pl I (mcnn 8.2). uhst~mtiall~ high Zn (mean 26.4 mg I). som1..· ('Opper (prohabl~ coming from copper

undcrcoat): Oil & < i~asc is not n concern.

In Acid< :nmid£' proccs-.. /.n conccntr.uion b high: pl I b normal. bccau'c \\astc:\\:.tll'f from Alkaline pre-cleaning is mi~cJ \\ith procc:.:-. hath and p(ht-plating rirbc \\.th.·r. The lo" c~anick concentration is inexplicable: rc:rhap' large dihuinn \\atcr from other npcrat ions arc mi,,cd \\ ith h.sth and rin-.e \\<hie\\ atcr

\\'a,tc\\ ;Uc:r from A lkolou < :nmide proces!> ha' consiJcrahlc com:cntrat i,rn ,11 /.n and c~ aniJl ''1th high ·r D\ < >thcr parameter" nrc not of conc1.·rn.

5. Aci<J_Zim: (C\ ani<lc Free)

·1 his rrncc ... s is \\idcl) usc<l in l'vla<lurai. I .111111 t\Jdll. \\hen .. · ill tiny and -.mall unit~. there,.., no treatment g1n.:n lo thl.' \\a ... tc\\,1tcr. /i11l 1.onL1.:111mtion i-. highest (mean 167'i mg/ I anJ the range'" \Cf) \\IJl 1 lllHHl~ all tic 1m1cc:-::. q11ian1-.: in fact it j.., incomparahl~ high Uflh)flb ntlu:r-. . t"learl). u...,c ill lh1 ... cq11irc:-. itnnll.'di:ttl'

a111.·111i11n in regarJ to \\llslc m111i111i/~1tin11 a-. ,,elf n...; pwccss n11>dilil·atm11.

3.2.3 Quali ty of Treated wastewater

Tahle 3.3 ... ummarbcs the qualit~ of trcatcd \u1-.tc\\atcr from tht: plant ... :-t11d1ed. 1 he folio\\ ing oh.;ef\.ations ma) be noted:

:i) li\e tllltls out of 21 unit<.. impart no trcatmi:nt h> \\,1-.te\\,llcr: thl.'se arc ti11) ''111all u1111c;. po1nt111g lo u !>1.ThHl!> pnihkm 11.1tilll1\\ 1dc:

a) pl I oi' treated \\ash!\\ ..ih:r b \\ =•11:., dcsir.1blc range. h) \\'hik the ml'an I"" , \\ithin Jucptal°'il ·· 1it. nnly in onl' unit. it b aboH· limit d \\ hilc •here is no limit 'pecircd ti.-ir TO\. in thrl'c u11i1:.. it i' nhme 2000 mg. I. <1

po1111 ol ennecrn d) ( 'r( VI) is gcncrul l} \\1th in limit and doc:-. not l.'aUSL' an) rn111.:crn c) ( r( I l range i-. \\iJl.' anJ high c\cccdcm.c in limil is nh,l.'1\1.·d in lhrw LJ'il.'~

indh:ating \Cf) dcarl) inadequate lrcalmcnt n Ni-l.'Olll'.Cntratinn mcl.'b stamlurJ in mo ... t (,l'\l':o.:

g) Zn cnn<.:cntration is "1th111 limit in mo-.1 <.: tsc..; hut cxcccJs in one. h) Cu conentralion is "1th in limit i) Oil & grcac;e 1s not a matter nr concern. generally "1th in limit jl C)antde i., general!) under limit I\) 1\mmonia N i~ ''ithin l:Jrnt: ... o is total residual ChlorinL'

In 'ummar). the mnin concern i~ inadc~u 1te rcmo,al of Cr(T) .md i'n. mdil.'ating inadequate pn.:dpitalion of lllCtJI <;I" .dgc " l" !gc handling and <..lor.tgc pr:ictil.'cS in man) umto.: ar1.· un ... ~11isfoctnr~. nel.'<l~ imprO\cncnt. Coll\enti11nal all.:nlrnc rrel.'·ritati"n tn.!atmcnt Jocs 1101 n:mmc: dis ... ohcJ solids. It i~ \l!I") imt:ri:sting Ll) rH1ll! that nni: (.EI P (run pri\ .11cl~) prO\ Ilks quill! !'>ati-.factor) trl'.atmi.:111. meeting all parameter ... 111J ab1l rl.'mll\ .:.~ high I I>..._ h\' re' ersc tlsm bis proce'" ·

-c (.)

c CJ)

> c Q)

..c (.) a.. (.)

~

~ -en () a.. (_)

Q) !...

..+-I c Q)

0 en > z w

_..... c 0 ·-c: . (/) ·:; c Q) .0 (..) Cl. u

en () 0.. ()

~

Q) '.... c <D ()

(/)

> z w

3.2.4 Water Use and Cost of \Vastc\\- Utcr Trc:umcnt

fhe \\ater use wd cos1 of \\ash!\\atcr treatment nrc summarized m Table JA. It is obser\cd that \\.lter use \arics \\idcl~ among unib O\\ing lO a large number of factors. Most units <lo not keep data on plating aren dul! to the fact it i: be~ ond industry pmcticc and thm where the~ do job-\\Ork. pricing is done on \\eight basb ~urface mcasurcmcm is 'eldom done. ; ·o,,ever. data from large integrated primary user 1..m ts r ak 1·e that water rcquirement \ aries from 68 lo 230 litre' per sq.111. of plated surtac'- :irea uf '\ 1-Cr plating. In 'nMllcr unorganbcd unit this \\ould still be more. Un comparh.on. World Bank n:commcml:- a t:irgcc of 1.3 lim~s per sq. m. of plated area for rack plating and I 0 litrc:s per sq. m oi barrel plating , .. herl.! dcctroplating b f\)lltind) performed on object::. \\ith knO\\ n surface area. Ckarl~. water u c in the industf) in the counti: is far higher than -;uch targets .

I h·· ... 1 of wa--rewater treatment 'aricl) rather '' idcl~ . It is pos~ible that accurate data m.1~ not h.i' ~ been furnished h~ the im.luslf); CH'll ignoring extreme ca:,c:.. the reported r.111gc: 1s as'' 1de as Rs. 30 to R . 311 per kl. In the pri\atel) nm CETP tl- <=charge le\ ied to Clhtorncr:, 'a~ trom I~. 0.50 to 1.25 fvr Im\ ·1 DS and Rs.1.60 10 I 7::., tor high TDS . ·i hb makes sense that for medium. smnll and tin\ units it \\Ould be !!Cm.a.nc •• economical to treat \\lble\\nter in a CE IP. C\Cll b) 1ai1keri;1g. I lo\\C\'Cr. \\he~ the un.its tn.:ul their 0\\11 \\nste\\aler. the cost of lrcatme111 i~ .11\\a) s helm' the gl.!nerall~ accepted upper limn of 3° o of iota I co:->l of production.

J.2.5 Air Embsion Statu~

hkc11opla1ing give rise lo l'llg1t1'vl.! -:mission Imm haths and pre-tn:atmcm tanks ,,f clcvatcu 11.!mperaturc. Vapours alsu c111am111. fro111 baths at ambient temixrature Prim:ip.11 COl1Stllllent~ ur concern arc acid lllmC'i. guscous pollutalllS antl voes. Tahlc 3.5 shows umhicnt a11 pollutants. It 1s obsc1\lcd thut the fugitive cmbs1un leveb an.! not hrgh but neid fume levels can bl.! rl!duced ... uhstailli.111} hy li.11111: col lcction and scrubbing "1th \\Utcr- mther simple tech111quc:s

3.2.6 Ncfr .. c Emission Status

Ele~tropla : g n itself does not in" oh c an~ noise producing activit~. The main cauw is mr hlo\\ers. lbt:d to suppl~ air to tan!..; agitation for pre-cleaning and ~ome bath:-. (e.g. \\ans Nickel bath). In most cases. these arc locaJcd clo e to plating tanks \\Orking arc3 and \\O~kcrs arc subjected to a sustained high noise le\ cl: predominant cause of higher noise lc'd [higher than i5 and upto 84 dB(J\)] is other induscri:i' act=vit) under saml.! _hed like machining. metal forming .. tamping. forging etc. Table 3.6 summarilC!> the data.

30

AcLh,il)

-3 Ni -Cr

Platin~

Ha rd Ch rome

lac ken inf!, B p hosphatin~

& hromatting c

( 'd plating ,~a ting \ ~fating Alkaline ·anide Free

Zn ·id Cyan ide

Zn

pl I TSS IDS 2.2- 3.5 8 -6 10 J1)R-

(2.9) ( l<J.7) 4.582 s~ Nole I (2754)

2.2 -l.3 388 14547 (3.1) ~ee 1\ote 2

L 9.7 121

I 3944

10.17 10.0 5830 --8.5 174 14()9 -

-7.2-9.2 115 2940 (8.2)

-

I 7.3-7.62 13-l 3036

Table 3.2

S umma r") o f Raw \\'astewatl'r Q ua li ty (mg/I. except pl I)

I

Cr (VI)

01-896

0. 53

see (6.

Notc3 99) -14.0 ))

1.0 I (7

B Dl

J> arameters (Runge & Mean)

Cr Cf) .. Ni ]-----Zn 2.0- 2.85- -

387.5 176.5 ( 167.7) (912)

2.03- - -1592 (452}

'ice Note 2

21.5 - 21

-- IO 6'J I 36.28 -- - 3.34

I

-

--t- --JO 2-- - l 42.6

-Pb 2.8

-

-

0.043 - 1.23 -(. u

;.9.76

I (26.4)

r~-- - ) -

31

Cc.I Cu O +G 2- 14.6

(8.3)

7.8

7.8

35.-U N.D - 22.19 N.ll

CN -

-

0 05

I ·-

0.109 0.06

-

I 0.014

co () a.. 0 ()) I--c Q) ()

Cf)

> z w

.,.__

\lk:tli1u· 7.fl.~-9 7 7 '"\-~ .(>-.-•_), I 35-121 3q_µ_ - - ,:;,() 0.01- 001-\;Ill idl' i'.11 (78) 517S :!I ~:! .flJ ~~ :,..;

- H561) - - {Ll3) - -- t C.

17.~,7) \ 7 ~7) ,\dd Zi1tl' J.5 ~4- 1 0!1 T 191..i- - "I -_,_

( < ·~ 1111 itll· F n·,•) I (<,7) (1llOX "' ..... .., -_, ___ , ... ~ ( }(J(d -I I (1675)

Notes

'I

3

.l

\\'h(~re alk.1hm: 'lOJk rill'iC \\~1 stc\\:ttcr is mi:\cU \\ilh plating tnnk nncl rinse \\!lier. pl I ii1crcasc-. to a rnngc ol' fi,SX - 7.1>0. \\ith mc.111 \~1l11c at 7 41 ( >b' inu.,J~ -;u\.'11 \\aqc\\atcr ''ill rcyuirc al'. id addition to lo\\ cl' pl I for Cht'P111ium 1'l•d111:1in11 In l~nc 1111~ h.1rJ rhromc unit. thcr(: is no 1rca11111:111 gi' en bcc:1uo;c of H:ry ~mall 'olumc. im.'.rc~1sing the ... ·om:cntration or poll111:1111o; to high k' d. o;h1m n h~:rc. In onc pl.11111g llllll do mg dull & bright '\.id.l'I on l'hromc. \\<tStc\\illl'r '' hight~ conccntrah.·d. -.hu\\ Ing tr( \'I) conccntrntion at 5 ~S9ci mgll I hl~ largc 'ari;uiun in cu111:cntrat1on of Cr. '\.i "a~h~\\:IllT i'i mninl~ due to '' idc 'ariation in 'I u:mtum of \\-all~r u-;cd for rinsing

ENVIS Centre, CPCB (www.cpcbenvis.nic. in)

T:thll· J.J

"um mar: of Tn·atl·d \\ u'll' ":1ll' I' <,..>ualil~

(mg I. c\ccpt pl I)

I' I ant Al'I i\ it~ r

f ',lr:tltH.'lCl"'ii ! - ----- - . ·~1~1F pl I ,~, IDS Cr (\'I l Cr( f) ~i Cu /.n C:d J\ g ' O& ( ·-..: -. c

.! (~ ·N cJ - ~ .. t-

- 0 .02. l 3.1'0 ·-- c: ( r. i'1·l'r & h.85- 26A- 1100- Bl>L- 0.1--W 0.11 • I 711 0.1 <J. -1.0- <ll.01 ti)

/ n plat mg 7.X S..J 7·~ 2 I ().{)() (0.-18·1 J I 2.50 I 1.x1 S.8 U.! I I I

·;;:

( 7.·11) I 1-IO I) n.t~21 ( 0.024) ( 1.33 1 ( 1.2·1) I II~ l I c

t ·L 1> l (!) ..a

)) {.) a. u

--1 ._ ~ IJrt1'i'i. ( ' I', ~I, l) 2· I l). (I J l50 II. O·I IH >I. I .7C1 1.87 i i . ll 1\1)1 HI >L ~ O.tlS

~ l 'll plating. ::>

~ .. +--- --.........

l d l'l.1tinc 7 18 12.0 3.w-1.0 Bl>I. (), ll ~' I 723 7.93 IH >I n. tr 11 Bl >I. <0.05 en i.c ---- (.)

\~ Pl.111111:! 7 25 10.) 1438 . o.w 0 171 Bl>I Bl>I. Bl >I <.0.05 ,, a.. 1 'h1 ,,ph.111 ng. x 2-8 " 1.8- 1026- Bl>L ' Bl>I.- 2-21 run. 0

( hwm.11t i ng ,'\:. I-Hi 1<117 ') , 0,09 ~ -I U.1d .. c111111.! c: .. (!)

I IP In\\ 8 " IS '5 BDI BlJL I 75 Bnl 0.1 • 10 .1 o o• < 0 5 (.)

I D=' -;trcam (/)

> z w

.. , '

--- ---t fnil /\ nnual Waler Use

I l11novr.:r Kl per year Rs. lakhc;

A 1500 6000 --H 70 675 --

I c 1 X.+ 750

~ -r- 14400 1:woo

I F 6.!4 3)40 I - -(j 7434 165.000 II 981 18.000

-1

.I n.a. 16.500

-- -- --- -K 11 a. 22.500 -- _..._ T 1..\,000 150.000

-v 4500 3300

._ ---A. I •II 140 -

Table 3.4

Water Use & Cost of \Vastc\\ a fer Treatment (~elected lllllb)

-- - -Trealmcnt Cost ·1 rcatmrn1 l'osl Trculmc11t Cost

Rs.lakhs per year R-;. per Id as 0/n of I urnovc1

2.10 35 0.14 2.10 311 2.90

Note

- - -4.45 I 593" I 2.42 "'Prohabl) lrcatmcnt l:llSt

I I includes other ens\'\ -- - -1.0 I 0.008 0.007 Ver) lar~r.rimal) user u!.!i!_

~- -~

2.45 I 69 2 U.JlJ ·-

10.97 I 6.648 _J_ 0.15 - ---- -17.0

I 94 .44 I 1.73 Docs plating on 2.65 ' In'

I

I :-l1.m annunlh. - LO\\ -1 os-o :j()i - CTTP

I ligh l f)0., - 1 . h~ (Pnvatl.!l) nm) lo 1.75

---~ '- -,- 111 - Ver)' hi_l!h co..,t _) ---- ·-

45 30 () () l l>ocs plating on 6. 50 \ IO' sq .m. ;.mnutil I:

- - --· (/11-pln1ing 1101 includr.:l_I)_ 7 --, _,)_ 76.36 0.06 11 igh Hil uc products. doc~ a

\ •ll icty of plating im.:lud111g cadmium. siln:1 & golu -

0.5 ::!08.11 0.·15 ~ Dul'.., s11\ l:r ~lating 011 Im.ts~ ... -- --Table 3.5

~

1 co 0 a.. 0

~ ...... c (l)

0 (/)

> z LU

llnit

B t----

" N p

-Do-

-- -Type or Plating Jone by

the Unit

I--

Ni. Cr. C'u. Pree mus meta l -1--

B lackcning/Ch romating

~...--/Ph<~h~ti1 l\i/Cr

'Ji/Cr/'/ N 11<. 'r/Zn/Pho

H!/Zn . -- -

11

s~hating

Range 1-------- ......_ __ l Mc:rn --~---

Air Emis'>ion Status

(Fugitin:: Lmissinn. micrograms rcr Nm 1 )

llCl mi~t H:i ~0 1 mist NO~

- 97 BDI. ---+---------!- -------0.61 ., (l I 6.2J BDI

-- -- -~

0.10 4. 0 ?6.64 BDI - - - -- ------- ---0.58 12. 82 22.10 13DL ---·t--- - - --

- 80 17 - 74 5

----~-~--- - - ---l 0.30 - 0.61 2.0- 12.82 16.23 - 97 BOI 17 - -- ------0.5 6. - - - - - 52.3 ncgligib~ 3

35

~ -c: (!)

(..)

Cf)

> z w

.r :::::

.r ~ ~ =-::: ,

.r

I; '.J

....l

/

.>.

I'.~' g ~

c.. ~ .r.

/

=

<

I

"";) 'J

u 'J c ... 0 u :;/J

....::::~ c

v; '.J ~ ::iJ ~ ~ 'J c ... :;11 ~ .,. c: 'lJ ,... ,.... c.. :::;

u ::J.

.:. :: ~J ... ,.. -~ · ;: ~ 'J ~ ,.. .... ~ .. -..

.!:. :,, ~ E ...

1~

x .

::

-, J.

-. c ()

c (J)

·::.; c (1) .c <..> 0.. (.)

~ -al 0 a.. 0 (1) "+-' c (1)

0 U)

> z w

.t3 "Unlnl:lr") or FintlinJ!"

lfa: lit1ding~ nl in-depth .,tud) is !'llmmari1ed a-. : I . l '.kctropla1i11g h) it:.dr ma) not l·on-.;titutl· tc1 he a lnrgc indu-.tr) b) l'l1me11lil111al

definittun of paid-up capitnl. Big ckc&n•'.' 1 '~': .. g unit., a~ :1l\\a)' a part of integmtcd indu-.trial proJuction (automl>hilc~. C)ck-. ell ). n.:l~·rrcd tn in 1hi" "ttid) ~1..- · rrimni') 11:;cr.;· I hc-.;c unit'i arc Li-.ttall) mcchani1eJ. opcr:lll'd "ith '-l'mi-aulumatcJ procc'' :'""'it....,• :111d bc111:r ir· T'"'11'llion control. oflcn emplc1) ing ml·tal r(.'cm c~. rin-.e \\atcr rer1rculatiu11 and l'ume colkl·tion :-.ys1em.

2. \ J'.'>t n joril) of llllll' arl small - propriet:u). panner:-hip or prhall' limited c11ti1ics (tumma ranging fr111n a' lo\\ as 10 lakh .... to 5 crures): these..· unit:-- \ar) ,,jJd) 111 -.c1-up. pla1ing pnicc'" C<lllll ol. degree of mechani1ath111. p1lllu1io11 cnntrnl ll'chn1qucs .ind ah1 ht) 10 mo<le11111e dUl' to ~c' l·r.11 rc.1 .... ons I hesl· unit... \\ ith :ilnui~t tow I manual 11pcrntio11 and \\ ilh lillk 1ecll11iul .... upl·n i .... ion need 10 hi.' upgrndeJ "ith \ ariou., le\ cb of B t\ I. as iJemilicd in Ch~lf>h:r 5.

1. 1 ... argc't nun1h~r of' units ar\.. ~'·~~tg-.!J in ~i-l r .. 1ncJ /n plating: ,,.,~\C\\,th.:r ch:.m1ctcristic:. v:11) \\idd) mainl) dlll' lo unor!!:i11i1c..·d ha11Jl111g. \\a~1d11I rin ... i11g. lad. of pru1.:cs:- COlllflll. I .1rgc number or sm:h unih do 11111 ha\ I.' an~ \\:t .... IC\\ilh.:r tl'l'<ltllll'lll fodlit) . di:.charging their u11trcmi:J \\a .... tc\\ah:t i11ti> rnu11icipal clr;.1i11 ...

\\ hc..·rl' trl'atmcnl j, dine.·. rc..·duc1io11 of< r (\'I 1 10 Cr ( 111) '" gc..·nenill) .=-a11,l.1"·1nr~

hut \\:t-.;h:\\:th:111flc11 l'nntains hit!li k\l'I .... 111 t ri'I) and /11. i11diea1i11g i11:tlkq11;ill· prc..'l·ipitution or metal ~lmlgc. l'hi .. lwlJ ... gouJ ltll ( ·udmium and llthi:r plating Ii ll\ "\l> prohkrn is found \\ ilh rc~pct"t to othl·r pollu1anh .. It i~ \er~ in1erl· ... 1ing 1l1 null· that one CETP (run pri,a1d~) pni\idc-. quilc :.ati:--facll>r) tn.:at111c111. mcl·1111g .ill pamnh:li:r~ and abo ~mm 111g high I()' h\ re' cr .... 1..· "'nwsi' proc.:.:-.-.

-l '-.lu,lgc hanJling and swragc pr.u.:ticl·., .;. 111:111~ unit:. urc Uthati.,f~n:lof} . lll'l..'d' 1111rro,cmc111. p:irtkularl~ i1 cont;iins ha1ar<l• .,..., m.1tl'l':'.1).;

5. Com c11tio11al :tll\alinc precipitation treatment Joe., 1111t remm l' di:-.-.111' cd -.11llJ, ~ lu-.1 elllucnh contain higher 1ha11 I XOO mg/I .: r _ ire oftc.."l "ed ::ts limit i1111thl'r indu:-.tnal \\a tc\\.tlcr. hen "ith sand Ii ltratiun follo,wJ h~ .1cli\ ,1tcd \.'arhnn Ii ltr.uinn. 11>~ a-. high a" 3.rn~ mg/I i~ noted.

6 Data !'rum large integrah:d prima~ lhl'r unit' inc.lil":tll' that \\al er req 11in:mc111 'aric-. from ClX lo 230 litres per sq.m. ol" plall·d :;ml:1cl.' area 111' \:i-t ·r pl:t1111g. 111 ... 111.1lkr un,1rgu11iscd units 1hi:-> \\oul<l ... 1ill lw more..· \., i:11111pa1 i-.un. \\ l'rld B.111~ recummcnih ;1 1.irgd 111' 1.3 litrl'' pl'r :.q. m. llf pl.11ed rlt'e~• l11r rack pl.11i11g .111J I 0 lian:-. per 'll· m Pl hJ1T1.:I plating \\here..· l'kc1n1pla1i11g t'> n1111i11cl~ pes 1;111111.."d 111111hjcl'l'"1th l..111m11 'urfricl' arc..':1. Ck~t1I). \\~111 .. ·r ll'l' in lhc indu .... 1~ 111 tlw l·, 1111111~ j., 1:11 higher th.111 -.uch lur~d .... .

7 l, I 111 \\,1Sll'"••lc1 treatml'llt \ark .... \\idd~ 1anµc..· hl·i11g I{,, :;o 111 lb. -;11 pl..'1 1..1. ""' 1 c of l'IX'rati1111 i.; m1c 111' the m.1in 1c:Nm' · lar!_!cr 1lw pla111. ic ....... 1.·1 i:-. the..· l.l,,I pc..T .... In the pri\,ltd) run Cl · l'I'. the charge le\ il'J to ~u--tontl'"' \:Jf) from lh. 0 50 to l.~5 fin k1\\ JDS nnd Jb. l.M' · · I. 75 fl1r I ugh 1 ()...., • I hi' mal,.c, sClhl' I hat l(u medium. -.mull and tiny units it \\1111ld hl· gL'm1i11cl~ cc11n11111ii::1' 10 l1l·a1 ,,a,tc..'\\:1tcr in a ('I · 1 P. C:\ l..'11 b~ tankcring Ilk '. IC\\:ttcr

8. \\ hcrl..' thr: unit~ 1rca11hr:ir •)\\ll ''·'"ll'\\,lter. th1..· cn-.t nf trcatm.:nt b ah\a)~ hdo\\ lhe gcnl'I ulh .1nl:pll'd 11prcr lt1mt uf Y'" ,,r tntal cn-.l 111' produc1ion.

-:.7

---c u ·-c (/)

> c Q.)

..c 0 0.. u ~

~ ._.. OJ 0 a.. 0

~

Q) s.... _,_, c Q) ()

Cf)

> z w

c: (.)

c: (/)

·5 c © .0 (.) 0.. t)

co l) Q_ (.)

~

Q) lo... ~

c Q) l) Cl)

> z w

'J. A .... far as air pollutant emission is concemc<l the fugili\'e cmission k\t•b are not high hu1 oc.:i<l lume le\ cl., can be rc<luccd subs1.111tiall) b} fume col lecuon and scrubbing with wntcr- rather simple techniques.

I 0. In most cases. \\orkcr exposure to average noise level is upto 75 dB(A}. \\here workers are sub1cch:d 10 a sustained high nuisc level: predominant cause of higher noise le\ d [higher 1h:.m 7 5 and upto 84 dB(t\)] as found to be other in<lustrial activity clo"c hy and under same 5hcd such as machining. mc1al fom1ing. stamping. torging etc

.-\mbicnl air qualit~ duc to fugiti\c emission of fumes and \apours \\Crc 'tu<lied. It \\as found that the o:-..idcs nr ~ulphur and NiLrogen an: quite \\ i1hin the limits of C'mcemrntinn of amhit:m air. \s far as acid mist conc.:1.:ntrnliom. arc concemc<l. thl.! average conccntr.tlion of 11~ S01 is 6.0 mg/ Nm3

. lhc I IC'I mist conccntrations art: neglig1hl~. I lowcvcr. this is Lo he 'ic\\'Cd "ith n.:.,pect to inkrnational st;rnc.lard becausl! there i"> no stanc.lard for 1his parameter in India.

.3X

Chapter 4

During electroplating operation::.. metal sails arc u cd pant~ by ckctro-dcposiiion of 1111.'lab .111d partly by rinsing and \\ashing. \\'hill.' lhc first part goc ... imu plating. the ""'cond part is lost :ind Jt; lually pose<; a pmhkm in "a'\tew:.Hl'r trcatml.!JH. E \en in plating hath:.. solutions ollcn nl.'cd-. to bi: discarded hccau ... c of prc~cncl.' and huilJ-up of impuritic:s that either hinder the efliuen'-) of pl:.ttin~ prOCI.'"~ or cau-.1.' deterioration in quality of plating. [i1her \\ll)'. the baths arc lu b1: Ji-.. cardcd before lrc-.h hath is maJc l'his is in<lced a \\aste both in monelar) lcrms anJ 1.'ll\ 1ro1um:: ntu l co11-.1th.:r.11iono.,. l3Jth regcnernuon h. thcrclore donc lo counter J1,card:r.:; 11 emird).

Variou ... melhuJs arc used for regeneration of bath-. and contcnb of prl.'-tn.\llrnl'nt. rin-.c and \\ash tanks. Thl.'~c methods an: briclly described hcltl\\ \\ ith lhcir speci lie ad\ amagc:-; and conslraints of use. Of the c method::.. mctnl n:cO\ cry 1hrough ion-exchange pre·ents highest poten1ial and .sencs the dual purpo:-ic of re ource {mc1al) rccO\cry and \\astc minirni~alion (by re-use of \\3ter of rl.'gencratcc.l bath solutions). I lcncc rhis process would he discussed m morl' detail.

.i.2 filtrution & Ccntrifu~at ion

Filtration \\ith tlr \\ithrnll centrifugation is 0111..· til'thc '"idcl~ used nnd cflecti\c method' for prolonging and imprm·ing the lifL" of h:ith. Although it doc~ nut dircctl) rcco,cr mcinl . it enhance;; the use of metal sails thu:. comrolling ~md rcdudng 1hc ,,a-,1nge of metal :>alls.

i\c1ivatcd carbon filter is ''idcl) used 10 rcmo\e dissohcJ organic impuritic.; (example: Nickel Balhs) in addition lo ib action in removing solids \ui.:h tiller:-. an: u;;ed cuntinuuu-;I) or inlcrmillcnlly during plating.

The rcmo' al of oils from alkaline cleaner~ b) uhmliltrntion considerably prolongs the life of treatment baths .lnd rl.'ducc:. interference b) oil \\ith floccula1ion and settling 'tep' during elarilica1ion C.,cparation of the grease tilm from degreasing baths b. another e~ampk of lhe u-.c of centrifugation or filtration. I lmH~\Cr. these arc not gcncrall) u~cd in small-.~cale operation-.. The ad\"antages of 1hesc techniques are:

• Fast regeneration of lreatmcm baths\\ ith high efficiency: • Prnducuon \\Ork does not ha\,c 10 bc 111t1.:rrup1c<l: • \\ aste1> result mg from these are h1ghh concentrated anJ thus could be

n!(..0\'('rcJ: • Disposal of residue-. is easier due lo IO\\ ,·otuml.'S and more com enicnt wi1h

sludge dispo~al operations of the rTP Nc\\cr methods and 1echnologics ha\e come up !'lllch as h)dro·C)CltH1cs. pad.cd-med1a filler:... and dectroly1ically enhanced cross-flow mt:mhranc clc.

39

..--. c (.)

c: CJ')

·5 c: <D .0 (.) 0. (.)

~

~ --al (.) a.. (.) -~ ~

c Q.)

(.)

Cl)

> z w

4.3 l•:vilporation 4.3. l General

Evaporation los->cs arc considerable in hot baths: 'im:h \\alcr llh\Cs can be C\llllpensatc<l h~ rcc~ding cascade rinsing (last t.mk or cascm.ll:) . In thcon. 1r the ii the effluent rate equal.., the C\<lporation r.1tc. a complch: rcco\cr~ 1>rhath chcnm:al.., can be .id111.H:d. I \Cn if complete rcctncl) 1s not m:hicH:d. sub:-.tanrial rcCO\CI) can cusil~ he nh1a1ncd

4.3.2 Simple Measures -. c 0 As the <;implcst C:\.amplc. the direct nx:o-.cry or plnting baths is realised "ith a static

drag.out tani... Rinse \\atcr from this tank 1s used tor the rcph.:nishmcnt ol \olun11: lossc:i. or C the process bath due to the C\ aporat1nn. Periodic \\atcr transfer from dra!!nut into the fl)

> proce:-.s tan!.. I' made manual!~ or heller h~ a small pump. Practical rcCO\CI") ratio rcalisc<l C: b) this mcthud is not usual!~ higher than 50 611 11 u. \tan) platers in the small scale CJ.)

sector in India employs Llus tcclui1que. {3

As an improvemi.:nt LO above. in case or cold bath, thi.: ti ragouts anti ~ontcn l s ur lirsl s tntic rinse tanks can be concen trated h) forced evaporation. 1 lowcvcr. app lication \\il l depend on the trade-off bct\\CCn cncrg~ and operating cost versus cost or n:co\ cn:d chemicals ('>uch a-; mctul salts). ( karl). this lcdmiquc IS ll...,CJ in C3'\C or C:\.pC11Sl\C chemical'> \ mon: <lcsirahlc: m1:thl)d \\Ould be to use condenser_" hich \\ould cnahk tn recin:ulatc the condensate (\\ater) to rin ... c tanl-:s and chemical-. h' lxuh.

-t3.3 Advancctl Techniques - Tin, Copper, Zinc etc.

l·. niciency or direct recovery can be signiticantly i111provcd b) the introduction of scvcrnl drag-out/ri nse tanlu arra ngctl in series. Such a tcchniq uc lrns been dcvdopcJ in Poland and applied in Poland and several countries \\llh encouraging results. 1\i1 lift pumps (made of PVC) are U\t::d for rinse \\atcr transfer from tank to t.111i.. and from the first rm .... c tan!.. 10 the plating. tank.( Fig 4. L ). The rdurn rates and opcning and closing of' alvcs arc automated ( controlk<l b~ electronic le' el controller and condudomctric probes I Depending upon the plat mg line output. the evaporation losses or the bath and the -.pace a\ailahlc in the shop. 4 dragout tanJ..s ma series can be introducc<l. l'hc tan!..<> c~m \\or!.. in closed loop system \\ ith /Cro dischurgc. This technique has be1:11 5ucccssfull~ used for Nickel. Tin and Copper plating baths and other hot baths reco\cry '' ith an cfficienc} or 85 95'Xi. It has also been used for n:covcry or co ld baths such as 7inc. " 'herein a small C\aporaLnr i5 used. Such a system for /.inc burn:! plating line ha5 been quite succc:-.srul. RcCO\'Cf~ rallo or /n plating hath \\<I" 98% {:.lhoul 300kg /n per year) \\Cragc \\alc.:r consumption t<x rinsing \\as reduced from 200 I ... q.m. lo 18 l/sq.m .. i.c. achic\ ing a nnsc-\\ater reduction or C) I%. Other Sa\ ings included:

I. Reduction of Energ) cost in plating shop 2. Rcduc1ion of consumption of anode and plating sails 3. Reduction in cost of wa'itc water treatment ..+ . Reduction of sludge volume

40

0. 0

O'l (..) Cl. 0 -(\.)

l........ c Q)

(.)

en > z w

PLATING

BATH

RINSE TANK # 1 RINSE TANK # 2 RINSE TANK # 3

* AIR LIFT PUMPS

Fig 4.1 · Schematic Diagram of Direct

Recovery System (WCCK)

(.)

c tf) .> c.: <D

..0 (..) a.. (.)

co (.) a.. (.)

~ ...... c <D (.)

en > z UJ

c (,/) ··-> c <D .0 u 0.. (.)

en () a.. u

~

~ ...... c: CD ()

Cl)

> z UJ

4.4 Electrolytic Recovery & its Economics

4.4.1 General

·r hi" technique b no\\ \\Cll dc,·dopcd am.I used in both large and :-.mall scale dcctroplating units. One maJor constramt of this method is that complete rccmc0 of the mc1al from dilute soluuons can not be achic,ed. ·\s 1hc metal salt concentration reduces. due to the metal cxtrac11on. the \Oltage must be rncrcasc<l in order to continue '' ith the cathodic deposition. Voltage enhancement is ultimately limited b) secondary rcadions. I lcrn.:e in practice, e lectrolytic recovery 1s used in conjunction with other methods. For example. electro!~ tic rccovi;ry of Corper from piclding baths has been succcssfull~ used.

I kdro-dialysts 1s one or the techniques in this group. In this technique. rinse "atcr is pumped Lhrough a stacl-. of ion-sckctiH: mcmhrancs that allm\ metal ions (for e\ample in "-!icl-.el rccO\er). Nic!..el, ~odium and other cation~) to pass through \\hen an dcctrical current 1s applied. Nickel passes imo an acid solution. ''hich must then be neutralised for re-use. O\'cr 9c.0

·0 of 1'\ickel can be reco\l~rcd and treating relati\'el~ largl.! H>lumes (of rinse water) is possible. I lowcvcr. since Nickel passes into an aciJ solution. it need-; to be neutralised for re-use. Moreover. membrane lite and scrviceahili ty can be a concern with L lcctro-dialy•"s systems.

1 he mo-.t common and t!ffccti\e means of reco\cry from dilute solutions ts by ion exchange method. Two most common metals ''cl-.el and Chromium rcu>\ery and recycling \\Ollld be dealt "ith. The technique anJ its economic 'iability \\ouJd be discussed in the folio\\ ing paragraphs in more detail.

".4.2 Nickel Rcconr)' I Recycling by lon-cxchan~c

Nickel baths are fol lowed by several counter curn:nt flowing water ri nsc tanks lo prevent earl") O\'cr and contamination of subsequent chromL' plating baths. I~ picall). Nickd ha1h soluuons of around 0.1 litre per sq. 111. of plated area is lost as Jragout to the nnse tanks. There are l\\O options to deal "ith the \\ash! \\ater (a) Treat thi! \\~te water b) alkaline precipitation and dispose of the \\3!ite ''"ater and put the sludge in secure landfill: (b)

Rcco\'er ~ickcl and rec)clC to l\ickel plating bath (n.:co,er) rate ~97%) and trear the balance 3% or so. A plater \vould choose the more economical bet\\een the tv.o desired alternatives. There are conventional ion exchange units as well as ad\anced ion-exchange uni ts.

In a conventional unit, the rinse \\ater is pumped to ion-exchange column containing strong acidic cation e\:change resin characterised by high capacit). good chemical resistance and stabilil). The resins exchange hydrogen ions and ~ickd ions arc retained on resin v.hich gets saturated '" irh '\Jickcl Salts after sometime I hen passing of °\lick.el solutions arc stopped and resin regenerated with 55 pure Sulphuric or H)drochloric acid. The regenerated solution contains Nickel ions in the form of l\i~01 or l\iCI_ . i\11 brightener and products of its breakdown are also removed leaving regenerated ~olution

42

free from organic contamination. The :-.olution can mm bi: returned 1t1 plating tank' -!>C1111-hrigh1 'ickcl and/or cri-Nickel. rhc comparati\ c t:cormmic comparison of a small plant j, ghcn in TahlC' ..i. 1

T:1hll· ·U: t:conomic Compari,on of\\'a ... tcTrca1mcnt "· ~ickcl lkcmcry (B""' 2.5 I.!! of :'llj\\O, prr cla~)

-< ·umponcnt

_~kl.cl Snit " I (15 per kg ~ulphuric Acid Rs. 6 per

kl? ----k-~~~-

1 lcctricit~ ~ 4 perk\\ h Labour

Chemical for Slud£C handlm1:_

I otal per da~ l ot.il pc1 ) cnr " 100

, .. ,,. ~ • :1•• davs/\ r .., ··--~

;'\ l'l '"'' ing per~ r

\\ a'tc Di'fHl\al rn'l R,. pt.:r tht~

~5 J...g 412.50

-Opcratin:!. Co"t CR~> of

Rem,·~'") "t) 'tern

IX

12 50

so ~4.000 1 -~

1.18. 950

C'lcml~. rcco\cr~/rcc)dmg pn:sc•1ts a \Cl) encouraging l'Usc in fa\lnll of its :Jt..hlplhlll.

C\l'll 111 'mnll plani-.. I lo\\l'\cr. tht: lJpit:il in,l·~tnll..'lll and Cl''' ol rcplacc1m:nt of rc~in must nl'o be con:,idl're<.1 f'or net ga :

h1r .1 •ootl qualit) el1ntrol on plaung trntl cunscqucllll) on the bnth cons11tucnt~. the li1llm\ 111g arc to hl.· con-.idcrcd

I. Co111:11ni11anh that h<l\ c accumulated in the iillSl' tanks should he reml1,cd hcforl' the l'\i solution 1s rccydctl to the plati11g b:itlis: Ir 1101. tht: rccyclctl cnnwminams \\Oultl buil<l-up 111 1hc bath and caltsc an a<.l\l·rsc effect on thr.;: plating qlli.1lit) and hath lift: Carbon lilter' me uscJ for this purpose

2. Brighteners an: usuall) ....,oJ: um !>alls \)f organk cornpnunds und the) an: con:.umcd I dcgradi:d 111 tnl.' plating process or lust to Jragout D1 agout 4\ctuall) pni' ides an important out kl for degrnckd brighteners and S(ldtum. Rec) cling pre:">t:nts follo" ing problems

degraded brighteners incri:asc rhc lo.id on Carbon lihcrs some decanting of the lank ma) be required to control Sodium le\ els Brighti:ncr control is difiicuh ''hen J portion is rec) clcd n.:c) cl111g tu scmi-hright tanks rc4uirc absence of brighteners of the hright b<11hs

3. RecO\ t:ri:d solution should be -.uflicit:ntl~ concentrated - a Ni-concentration of 35 40 g I i~ acceptab\; ,. · direct rec) cling

4. Rec) dcJ mh of. ~i !'\alts '<..dphatc nnd Chloride in a particular ratio) should Ix: -.:unc: as original mh rauo

4.3

~

c: (..) ·-c:: . en ·s; c Q) .c (.) Q. u

ca (.) Cl. (.)

~

(J) ~ ......... c: Q) (.)

(/)

> z w

. Cf )

> c: Q)

..0 0 0. 0

~ ..._

cc (.) a.. (.)

-~ ~

c <J.)

0 Cf) -> z w

' pll of lhc n.-c~ clcd solutmn ~huuld be 111 l:Om'\:I mnge b In some :\:i-plating baths. ll11: ~i c:unccntration build' up bc)ond 1hc rcqu11cd

li1111b. rh1s occur~ due to lhc lhc d1lkrcncc ol the current d1i .. ·11.:nc1c ul lhl' cathode and anode I he .uw<lc cl li'-1cnc\ doc-. m fac1 .1pproach JOO• butr thl' c.uhod.: erlicicm:) usuall) tall-; m the range 90-96° o: thi::- cau~es more 1\1 .mudl..'. di~'olution into the h.uh !>1Jlut1un 1han \\hat h bcm~ plated and 1he '• conccmntion and pH in !he balh ''ill m ~c.1 ... c I h1 prohkm can be ontmllcd \\ ith 1hc lbC of peciall) designed insolubk :u10Jc-.

iii~ JJ\ .111' .. cd rccm er: '~ 1cm u<;111g run-cxch:rngc pm.:c-.-.. 'umc of the:,\.' probll:m!> I .t • l been tackkd to prO\ idc better cflic1cnc) and Jll..·rform.incc Tl11 ~ l~ pc of~~ Mcm u c' t '" ,i.urt packed rc~in cq!P.!!l!.15 {1 c .. callun and .1c1d ~urptmn) \\tlh lull) .n110111alc<l ••1w1 •t11111 I conomic compnri-.1lll 1s "hcw.n on 'I :1hll· 4.2 .

I :thk -4 .2 Economic compari,1111 uf 1\ch i111n·1I lnrH~\ch:in:!l' ~ickd lh.·co' l'r) ' s. \\ a'll' ·r rcarmcnr

( lfa,1s: ::?.' tuJ.O ki: hr llrni:uuc 11pa1111unJ

-Component \\<I Sil' l)j,,)1),:11 \'U'I

lh . jll' r cla~

\Jich "'"' t 11lphah: - d.: ritk

20.000 ~1! lh

!!_I h5 per J..:g '\ ' ' o II) d1uchloric Acid ''

It) 4.000 mnne ~~~----f---~ ln°., Sulphuric \c1t1 1

R:i. _6 .lll~'!...r>er tonnt: i I 00'} .. ( au.,t1c Soda hJ 11111111.·

'! lb. I S.OUO_pt:r tonnt: • 1111

' o .... luJgc 1 handling 75 to111w

!.! R:- ~O p\!r tonne ___ _

1.100.0110

R!> .''·l .5!10

R,. 17.5110

l'l.1111 \\.tlcr ,, Rs. I'\ per 45.00() Rs.

CU.Ill Cll.111. h. 7 ~ ,IJI)()

I l \I \\ aln a Ks.~5 per l.'.U.111.

1

Opcratin!! Cu,t (I{:-) uf Reen\ en s, ''l'tn

' . 200 kg R.., -; •.ooo

2.000kg R!\. l\.000

CJ.000 kg Rs 5-Ul(HI

7 5 11111m: l{..,,112.5011

-0. 75 tonne R .... 37'

t- . - .•Hll l CU.Ill. lh 1.35.11011

I 11tal JK'r ~ear ---~--

-t-41.07.UOO 3.-i:uns ----....--

Ji.h ... 125 "'er Sa' in:.! J·Lr ~car

I It 1pcr.uing .1d\ ::rntagc' are. • \\:0 dilute ri~..: Iced ~uluuon (· O.S to I 0 g I as NickdJ re,uhin~ in high

concentration purilicd product ( 1' .HJ g, I as ll:kd)

• Org:rni~ b..;:: 1tencr-. arc rt:Jcdcd nllcm 111g direc1 rcc~cle 10 ,emi-bright bath'i • Pre\'ents ~udimn build-up 111 plaung hath • Rcgcn1.rat ... m of rcsm \\ith u mixture ol ulphuric and H~drochloric ac1<l

produce~ a mix of :'\ickcl 11lphntc and Chloride that m::uche:-. hath chemistr)

44

l

• I .xcc~s I cgcncn111t ucids from lhl' ini11.ll prodrn:I ur lhc Iii sl 11." .. 11\ hcd .Uc

'nrhcd \lllt in the c:ccoml r~ ... in~ed n: 111li111! 111 lhl· lin.11 '\.11:kl'I prml11c1' h.1\ ing a pl I suit:.ibk for direct rcc~d~

In ~kc111-atl\l' r>l.11111g. olil~ .1b<'lll 15"1 nt Cl1111m11. \1.:1d .llllicJ 11• llll· h.11h .1L1unll~ t!Ch plntl'd llll the ohjl.'Cl\. [he halancc j, Jm.t ,1' llr:t,t'Olll tn ril!-.1.!\ .111d r'Ullh.' 'l"l llhl,~rs (. l.::ul~ th1-. 111d1i:.1h:' .1 huge \\3-.li.' or' metal. \\h1ch ,., .i1 ... ,1 \LT~ hM.11do.i' \ 1nr.:o\ 1.·r. d1.·c1•r.1l1\C

·'' \\Cll .1-. h.ird duomc plalmg hath ... hccl•mc t11111.1111111.1h:J 11\cr .1 1•c1111d nt 111111.' Jul· h•

d1,s1•lutlllll ol 111c1al-. from th\.· plati:d l·omp1l11c111, .md 11thcr op.:1.tllllll.tl l.1L·l\11-, I hc-.\.· <l1,.:')of\cd c.1tionic c11ntnmin.m1-. (lri\alcni l r. I c. '\1. { u. /11 ell') hmL·r th.: tlml\\in~ p1)\\1.•r 111 the h.11h and 11)\\Cr Lllm:m \h:n,ttic::.- I h1, rc ... ulh 111 -.111\\L'I plalm..! opL·t.1!11111.

\:011-.uming more cm:rg~. Plating llt1.tl11~ j, :11._,, .1d\l·r-.d) .tltcch:d \II thi:'I.° t.11.1or' 111gcthcr (1.l.' .. Jdccb 111 .-.ur1:11.c coaling. m;i1cn.1I hi,, .111d co ... 1, ,,f tr1.'.1tmcnt .111d Ji'!"'''·'' tu ulmpl~ \\Ith pollu11on i:n111rol n•gul.11u11h) k.1J ll' punfo:.111nn .mJ 11.'\:~dm_ 1'1

{ hrom1c \c1d.

(om i:ntiun=il ion-exchange has('d rcu)\ er~ ")'>tern 1.ompn:.c' \:311011 ,111d .1111\ln cxch.111ge columw.. 'he lir;t column. containing cation cxch:m~c n: ... 111. n:lllP\ C'- tn\ .1k·nt ( 1. '1. I c. ( u etc I he dtlul·nt. then containing onl~ hcx.l\ .tlL·nt l 1 '' p:t.,._l.'d 1hmugh a1m•n 1.:xd1:tngc rl',in 1111' rl"OlO\C' h.:\.,.l\alcnl Cr. !cu\ mt the clllucnt lh .. ·1.· lr11m .tll ntL·t.tl ,,111, \\ h~·n the n . .:s111~ gd ::.atur:itcd. thc) ar\.' rcgcncr .ucd Jnd rl.'1.m u cd <. hru11111. \i:1d ,.., ICC~ dl.·J 10 b.1th-. l'h~ e<.:OllOllliC COlllpJrison j, 'h\1\\ 11 Ill rHhk ... J

lh: CO"t or n I) pical IC'lcall) manut:1c1urctl pl:1111 (of 2.5 h.g C:hrnmk \.:1d n:1.1l\Cr) l'O'-IC,

Jbout lb. 1.00.000 \\ ith u resin \Olumc of 50 l1lll''· I h~· cu.-.t ol l'l',111 '' R, hf1 1 p~·1 lim: ''ith mirmnum lite l'f I ~car (a, crag(' lifi: j, hl'l\\L'Cll 2 ll\ ~ ~1.·•11-.) I he dcprcL·1.it1un ·" ailahk 1m thl.' Ill\ e.,tmcnt 1s I OU 0

o. ·1 hactOrL' pa~ had. pcnod '' ah11ut ,, ~ l.!.11

I :t hk -l.J: El'onum k ( 'om pa ri-.on nf \\ a'll' ·1 n ·a I nwnt ''· ( "h rumt• l{n·u\ t•n

(l!a"i': l5 I.~ nf ( hromtl' \r11l rroun '1:111(" l{tn,C \\ :l f('I ' lll' I tin ~ I

-r ( 'umponl'llf \\'~'''l' J>i,po,:.il "~"' Op<•rutin!! Co ... r (lh) or

I~'· p~r da~ lh·co' er'\ ~~ 'h'm Ch;omic Acid a 110 per

-t- • 2.5 kg 27~

k_g_ 1 'odium :\1c..·1ahisul1 hitc a 7.5 kg l)(l

Re; 12~rk~-~ t - ---- t C.mr..ti '\uda a Rs 1-l per 4 kg ~() -1 li.: ~(,

"'~ - l ~.i\ ing nn Sulphuric Acid 2 kg 6 , kg I l ~ lb. ~ (_)Cr kg __

I lcclril·it .. ' !! -i r1.·1 k~.!!_ 1 ' 1 12 I 0 411

I ahow I.:-. 'ii) I "' 50

45

-c u ·-c CJ)

> c: Q) ..c (..) 0. , ' v

~

~ -ro (.) a.. (.)

Q) s.... ... c Q)

0 (f)

> z w

l hemical tor Sludge h:mdltn!!

'\a\ rng on plant water (after rec\ cling)

I I otal per d3\ I - .

I ot:il per ) ear ~ 300

l '\

LS

-I

,

5

496 .-18.SOO

- - -----

158 -- -~- -47..tOO

~ "orkine da)s yr

Net Sa' ing per~ _l_ ,_ I

-j- 1.0lAOO

I k"pitc such em:ouragmg res uh~. coll\ enlional ion exchange recO\ er: s~ ~1em~ ha\'e one · 0 problem. Direct ret:) cle of the dragout 'olution 10 the plating hath "ill also rcc)clc thl ·c; mct.11 contaminants and lead to build-up of conrnmin:mb a::. rec)cling goes on. 1\ cJ5 dfo.:ti\l' recycling ~~stem has to incorporate ho!li rccmcry and purification. HO\\CH:r. ·5 Jrngout solution after purification could be h\C.> dilute for direct rec) cle lo the chrome C bath \ good arrangement \\OUld be lo U'>C an .llmo'>phcric evaporator for the purilicJ 15 n:c.·\ ch.:d ~olutiun. The a\ ailabilit\ of l\\U or three counter Ill)\\ in~ rin-:.e tani-.3 in the U • • - Q.. platrng line could ensure a high degree of recm er: "ith ... uch as~ stem '°'er 40 - 960,o ol (.) drag.mu los:-.\."S) with the po:.sibility Cit" also reducing rin~c \\aler requirements b) 70 -::;. XO" u > The economic comparison of larger c:ip<icrty planb is given in Table -t...t. ~ Tahlt:-tA:Economic Comparison ofChromt· B:tfh RccO\ery with Treatment

(ha~ed on 3,-85 litrc" h:llh \Olume: H ll j!. l ch romc: I S crl met:ils)

Item Advanced Ion- On-.,.itt• Treatment Off-site exch. S stem Treatment

l3 a1'1 11.: ') laccrnent Rs I . 10,500 Rs. I .50.500 t ht:miculs R~.23. 1 77 Rs.7..J .605

Sol id'\ Di ::; osa l Rs'\7.663 l 14u1d Dis osal

~--4---

1 ul al Co~ts ___ __;. __ R_s_.~_,.44.000

I

R'>2,82.768 RsA,9-t,500 Rs.29.154

......_..

cc () 0... ()

(/)

> I~ pic<1I ret..:0\ cr) dlicienc1es of' ariuus techniques and methods. including simple static d] rcc0\e1~ nnse used by most of the small scale pl.111.:r· arc ~ummarised in Table -t.5 1111\\e\ i:r. it may be noted that the reCO\Cr) ct ticicncic reported here are onl~ general 111d1c.uor.:.. Propnetar~ processes and techniques u ~ing ::>nmc method can achie\ e higher ct'licit.:111.; il's. ·\bo. adoption of a particular tcdmique depend~ not onl) on metal andlor chemical ret.:O\Cf) effic1enc) but abo on effect on plating quality. O\erall eco1wm) and ,1\ ailahilit~ of operauonal sJ...111. \\ hale\ er the 'ariant. metal recon:11 rnl.'ans 1 i J a slr:iighlfomard pollution abatement at 'ourcc. (ii) a cleaner production proces:, and <iii) substantial saving of \\'ater.

Re' cr-;c Osmo-.is is one of the membrane filtrntion technique • in \\ hid1 the por\' "/c of the mcmhranc vmics from I to IS Angs1rom and lhc liquid is fihcred through ;.1 ... cm1-pcm1cabh: membrane. ''hich allO\\:-. onl~ ''mer molecules since the pn:.,surc is mun.: than the osnwtic prcs:.urc. Application of this proce ... s is l:mscd on the fac1 that since.: th1.· Rl 1 membrane normal!) rcjccb compounds and ion..; ahovc n molecular \\eight of 150. mn't of the ion' \\ill he rejected. When rm.,1. \\ah:r i" ~ubjcctcd to RO. \\atcr (\\ i1h ~om1: compnunds) \\ill co1•1e out :.h permeate and thi' r1.·st of the chemical" \\ill r1.."ma111 111 th1.· con\.'1.·ntratc or n:icl'h. ·1 he 1.oncentr·nc can be rec~ clcd to hath. I' his is pos!>ihlc '' h~n rin:-c.::- from vm iuu' prm:1:,scs arc ... cgrcgati:d. Ir th1:~ arc mi:\cd. th1.· con\.'cn1r.11 .... "i 11 cont.1ir• a varict~ l'r 1·hemicab and oln iousl~. it "ill need h) hi.' C\ aporntcd '" i1h -..liar cm:rgy1 u11d -.!udgc dbpo:-1.'t! as huarJou' sludge. 'I he major limiting factor li1r ll'l' 11 1 J{< l

s) •acm " the prl.'<:Cncc: of Iron and free Lhll1rinl..'. "hich the llll'lllht-ar1l'!> an.' 11111 .1rik 111 \\ ith,taml. c.iusing ltllll ing llf mi..:mhranc Ir sufllciL'lll pn.:-lrc~ttmcnt pl'Cl' l'<IC' HI I llh.''l II is a\ iablc altcrnati\c to ~Of1\ cntional S) .;tern.

I he proces. h:is been in use in Bl IF!.. ·1 rkh~ :.incc the la~t four ~cun .. r'or l..'hromium plating rinsc-\\atcr '' ith n ca pal: it~ of 50 litre p1.:r hour (pcmH~.llc). I he -..1\ ing" :11. h '- H·d h~ lcl\\Cr consumption of\\at~r and 1.:'hcmicals pa~ for 1hc pluru in ahnut t\\O ~~11' \ll•r. lacililic~ like this arc succc-;:.full~ hdng huilt m i\lat!urai l.lcctmpl .. ucr-. · p.1rl rn \l.ulur.11. and othi:r parts of Tnmil N:1du

.t7

,.._, c.:: ()

c.:: (/)

> c: Q)

..0 u Q. u

ca () Cl. ()

~

Q) L~

c Q) ()

Cl)

> z w

- L I c .::! .:.e. s.. :J :JJ r ..... ~ ,...- -< :r.; -

' .... :ti :. t: c c.. - >- 0 c..-" ..... ..... ::.:; ::. ~ ::::-'...; ....

:.. - r. c

E .... - 0 v, 0 ..... g: .J: - ~ u

---·-- - -.. c :11 .2 c ::I 0 .. = .:::. c .... ·-E '": ..... ..... .... 0 '=" () ~ ..... ,_ --'

....... ; c . '--f/) ~

:Ji 0 > ~ ~ : 0 ...... c v ..... ..... 0 ,,

' . ::.:: ~

Q) - ..c ~ c (.)

Cl ~ :;I;

c. 'J Q. c - ::::! c ,,. ... = ..... .... ..... ..... - u - -::

' ~

~ :: .; - ~ - 'J _,

..... s - ~J ~ .!. ..... ~ - -" E 0

~ c ._ ... - - - ..... ..... "'· .,, '£. - ~

O" CD - ... -= -;...

0 ~ = ":11

" a.. ... - 0 fJ gJ § 7i - E ' 0 ,-... c c ~ ~ c :; ~ -:.> ..... ..... ..... , ... :;:. ... 0 - ..c . .) ;;. .; . I '?' - (l) ... ~ e ._, c - 'Z. ~ So-~ ,.,,,..~ .... , +-' .. ,_ ._, c ,

r:.. / Q) = ':,J ~· ~ ::- J. (.) ..... ..... .... .... r.r.. -.

0 . -- / :. Cf) -~ .!. :. - -"'4 --r ..., > .... :i, ;_. c· .. ..... = . c

" z a. :i :.. ':,J c. ..... ..... "'· ~ ~ ..... .. ,, ~ w

':,, ..... -:.. - '---

_...._ --1 -:::: j ' ~ .... .... :1 - ~ .... c -- C-. 0 :. -:: E- - Cl: ... "· C" .... ~ -

:.. ':,,

2 :. :J 'J - g -:.

•.r_ - .... .;. ": /

v . / ~

'"T 'J .. t J

-= ..J .. : /

:: "! ~ =. :. -:. ....

......

1= - 7 ~ .J •..; .... / ·~ .... . ':J ....

.... :.. __ J 0:: I ::::::: j -lo._

Chapter S

\\'a, tc Minirnio;arion & frcatmcnl to C ontrol Pollurion

~.l c;~ncra1

t:lcctroplnting generate<> .111 thr<.'c form~ of \\3Sh.' liquid. gascou' and ~uhd Of the-.1.. liquid \\a,tc' arc prc.·dominnnt. Such liquid wnc;tc:. include : (i> spclll chem1cab .1111 1

olution" 'uch a add . all\alics. ckaning agent . hath chcmic3ls cnmpri .. ing plat111~

1.:hcmil:al' as \\CJI ac; ndditi' cs uch .1:- brightener'i. le' cllcrs etc. and ri11~1..· "ater .... "lud llHI) contain some or all nf these dt!pcnding upon sources. method 11( pl.1ti11~· ,11

hou~d.ccpmg practices.

(iascou<\ wn•ac-. include ~ol\'cnts and vapour:.. from hot pre-treatment and pnH c'' h.11h l°hl!) 111dudc acid nlkali mist. Volatih: Organic Compounds (VOC's). In ... 01m· c:,,e, 1111'"

nml \I<)(', lll'1) contain mcli.llS in addition to prrn.:c~S chemical~. J\ccn11.lint• h1 0111..·

estimate. approximately "'0° o of the o" ents and degreasing agcnb u-.cd c~m he 1\:lcJ~\.·1.I ll'i VO< !. "hen haths urc not 1 cgcncr::itcd.

~ohJ ''•'"'-·' include. sludge;-; generated from \\astc\\atcr trcatml'nt. -.111dtt'-'' lru11 clc:rning <t11d hath tank.; and va1 ious residues like. cll.'aning pm\Clcr. hul'lin!.! co111p111111 t.... 'J>Cllt nnnde'i .md 'ariou~ -scr:1p l nuscd c.·hc:micals. 'pent rc-.jn, frnm illlH:\\.:h.111gc m'-·1.tl rc1..'ll\CI) s~...,i...·mc; abo contrioutc lo solid \\U'itC. \1uch of the ~{ll1d "·''!"' ._,1111.1111 h.11J1rdnu'i and 1oxk .. ub-.1a1wc~

\\ '; 1~11.· 1rn11imi.;~1til111 1hacli11c nccupics the ll\O!'it 11npor1u111 po,1ti11n 111 th~ •1111111

pollu110n from clcc11oplnting and m era II protection nl the recipient cm ir11111111..111 ". 1" .1ir and land (s11il)

5.2 \\ .:i,lc ~lininm;Hion &: Pnu:~'" ,\1ndification

Wa:-.tc m111imi,ation in an Elcc1rnpl111ing unit m.1~ includi: !Ill) nm:. ~omh111a1 i1111 111 ~111 .11 the follcming. I. ~1i11imisa1ion of \\'a~lC\\ atc1 (il'11l.'1:ition 1 lu' '" th1.· single mo't signific.mt step IO\\.ird., "·''ti: m1n1mi:..a11on. Thl· rc,uh" of the 111-dcpth st11~ly pointc; lo .m imm1.•diatc need tO\\ard~ thi'i ohJcctiYc. \\ hilc the !Jrgc .111.f orgJm cd unit' practice full or pJrti:ll \\J'.:>tC\\:ttcr 1111111misatio11 ... mall <.1.·.1lc .tnd ti11~ 11111t., do not do <1n) thing 31 all ~lmH:rou" "tudil·-. reportcd m litcrntun: also point 11ut to'"·. ual npprnachc~. "hich c.111 he brtcfl) ~tatcd a:>: • I ntroducuon or rin"c "~lier recirculation '' 11h nutnmntic h1..·nctit • •f chc1111c:1I rl.'tll\\.'1)

and n:ll:i1..'

• ~tat11.· rinse water recm cry • \\oidmg :md controlling spilla;;c - !>inglc largt:st cause uf high \\:1'h .. '\\atcr

g1..·11cratil'll 111 tht? unorg.miscd :-ec1or. !Jy using troughs bct\\Ccn um\.s ancl using \\Cll defined linear configuration in place of barrels and a' 01ding hapha1ard rin,ing and ,,a_ hing will ensure \Cf) signitic:mt reduction in quantum of wa,tc\\atcr gcn1..·r.itcd

--c ()

c

co () a.. () -Q.)

'+'"" c Q.) ()

if)

> z w

. (/)

> c Q)

..0 0 0. 0

I ...._

a:l () a.. ()

-~ ~

c: (])

0 Cf) -> z w

• 1 ntroductilln or l:a'\l:aJc and or counter- current nn.,mg

• l lsc of fogging .mJ ~pm) ing on obji:cts (ruck pl.1tmc)

• l111roduc11on of metal reco\e~ b) clcctml)t1L methu<l (mn-c,ch.mgi: and it!> ad\anccd application leading lO high rt:~l'\l'J) l"Jtio or\\ ater ( Upto 80° o).

Anal) ses of cost sa\ ing b) metal recO\ en u.,ing 1or1-1::xch:mgc pro~c,.., indii:.1tc !hat for a ;;,mall scale plan! a 2 ~ 1-.g Chromic add per da) and 2.5 J..g Niclcl ~ulphatc per da). gro's !)3\ ing \\Ou Id be Rs. 1.0 I l::ikh and 1.20 lakh per ) car. For large plams a 2.5 kg Nickel Sulphate per hour. the ..,3\ ing b) ~td\anccd ioncxchangc ''ould be lb.37.64 lakhs per )C~tr.

2. ~timmisatinn of Gaseous Emissi1111

I :~cc pt .1 fc\\ :-.tall:.., (e.g .• ~arnataka :md ~ l.thamshtra). Stah.: Pollmion Com ml Boards do nm generally require dcctroplming uni1s to provide an) mca ... urc for dimination or control 1.lf g;1scous c1111ssio11. J\s discll,!\cd earlier. gaseou-. emission take~ place as 'apour~ from hot haihs. nomH.11 C\ :1pormion from colJ hath~ do not constitute significant source of such cm1s~ion .md \'( >C~ from organic cleaning oaths.

l s~ of collecting hood' and scruhhcr, can s1gmlic:1111l) control or eliminate ':1pouf\ lrom bath-,. Colltxting arrangcmenh h~I\ c 1mpru\l~d suhstallliall) hut oldl..'r pl:rnt" either hi:l\ c no collecting hoods or onl) !'Ilk l\Uction arr.mgcml..'nt. \\hich Ufl' not cm.-cai\e at all. Complctcl~ CO\crcd h.1ths .m: ideal solution but the~ :m: u~dul in compktcly automated plnms .is u::icd in Luropc and parts of North America. I lo\\C\cr use of top 'uction hoods '' ilh propcrl) dc,;,igncd sc1uhhl..'r system certain!~ control .. much of the ga .... COll'- emi ,,i lll . , ,, fo1 3'S l'llli .... ion or VClCs .:ire \.CIK\.r ll . "de:tl !>llluti,111 i~ not to ust: thO!>C .\ ith high i!ll\ iro11mcnt.1I .. 11nccrns (discussed in ~i'ction ~ ); l!'v~n if they are used. the hl!~I pmc1ice j, 111 ~l'l'P thc rnnJ..., lull~ 1.:(1\crl..'d .11 all 111111.:., and using' apour arresting de\ kc.,

3. jvlininmation of Solid Wust~

Mu1m part of solid wastt: tthal hlll, lrn1:ml11thl ts ... 111dgl'. frnm \\ll'>lc \\Utl.'1 lrl.'•llllll'llt

plitnl I hcrcfore. if mcasun:s :11c wkc11 111 111i111111isl.' \\.hll' \\<tll.'r gc11l.'ra1i1111 h) n<lnpti11g llll.'tll<x.b slalcd in ~uh-p.11.1 I ;1ho\l'. ":t'>IC \\:Iler sluJg1.: gcni.:rati1111 '' minimi,cd. Other cons1itul!nts of solid \\,1stc ari: : II) spi.:111 anode-.. (ii) t•111k sludge ... . (iii) 'pent carbon filters and (i\) l.'mpt) cu111.11ner of chi:mil.·als Cle .. The la:-.L-name<l one is lhUJll) sold 10 'crap dcJkr<;. fank .. luclgcs and c;pi:nl \.'.arhon liltcr' 111.1)

conmin hazardou:-. metal :-.nlL. \\ hilc 1hc ljU.mlit) depend~ on production. dbpo-.r1I prac1iccs ~hould conform to rcgulatol) rl.!quircmcms pertaining to ha1ardous subslancc~. Therefore u-,ing 11011-hazar<lou" chemicals \\ill lead to minimic;ation of lumird in ,oJid \\aste from procc '> chcnm:.11., U:,c of C)anide free procc-.~ (e.g. \llalinc C)anidc free Zinc plating). U'-C or lmaknt Chromium in place nl

hc\a\'alcnt Chromium are example. of such h:v.ard 111111imisat1on.

4 ~ini1111sauon ol '\Joisc I.mission

Plating aCll\ il) b) itself tlocs not produce signilicanl noise. C'\CCpl harrcl plating or .... mall obhects. \ lajor source! ol noise! is opcr;.ition of air blO\\ crs used for hkl\\ ing air 111 plating (for Nickel Plating) and in pre-deaning opcra1 1nns ~u<..h ncw;L i-. minimised b} pulling the air blO\\Cr in a separate room \\ ith noise nwrll1n):!. ;.irrangcmems. In man} plams and factories. ii """ obsen ed that high amhicnl 1l01sc k\C:l in pl:iting areas is caust.'tl h~ <lLli\ ities other than clcLtrnplating. such a-.. rnach11ung. stamping .. netal fonn111g.. forging. cit. etc -...,rn..,c rcJuc11011 Ill such :icti\ itics is hlmcvi:r. outside! the punic'' of thi..; .. aud~

5.3 Best arnilablc TcchnolOg)' (BAT)

5 .3. 1 General

nu• /Je\/ /l•(li/11hh 7i:dmitjllt.: { B ,, l ) ll1Ctlll'> lh..: 1110'>1 cllccti\\: and uth .im:cd 'il41..!L' in 1111: ~k\(.:l\lpmcnt ol acll\ iucs anJ their methoJ-. 11f 11pernuon. "h1ch indil:ate 1hc prat:lh.:al suil<1hilit~ or particular tcch111qucs lor rr<n iding. in rrinctph.: lhc ha,1s for rni111mum cmis~1on \alues Jes1gncd to prc\cnt anJ. \\here it is llllt praLt1cablc. gcnerall) to n:Jm:c L·mi-.;;;1nns and the impact on the environment :l'\ a \\hole .

I £ClrniqL1g;;; include both the technology used anJ the \\:l)' 111 ' ' hich the 111 ... tulk11ion i-.. Jes1gneJ. bu1h, mamtained. operated and decommissioned. including also training. ~ailablc 1cchniquc!-. means tho-:c dcH:lopcd on a s<.:alc \\h1ch alhms implc1rn;ntation in industrial sector undt!r cconom1cally and ccchmcall) \in hie conditions. taking into considcr:-it1on the cost'> and ad\ antagcs. Best mean-. most clli:cll\'C in achic' ing a high gl.'ncral k' cl of protection of the cn\'ironmcnt a~ a "hole.

lhL: (lOJCCti\e uf the B ,\l' <iurddmcs IS to pnnidc a h-.t or technique-.. mcluding li.:ehrwlog.ic-.. \\ hich ''ill prm idc gui<lancc lo the local n.:gulator~ hndic.., and the industries \\hen tktcnninmg B '\ r for an acti\ it~ . I he n \I' identified in lhi-. Report IS

int1.:nJcJ to control and 'or minimise polluti1m and 1mprm c thl' cm 1rnnmcnt•tl perfor111.111cc h) 111cnrporallng the technological ad' anccs as the) occur.

In the ic.1cnt1ticmion or l3t\ l. empha ... 1s is placed on pollut1011 prC\l'.nlton tech111qw.: .... including clcam.:r icchnologic.., and waste mininfr,ation. rather than cmJ-of-p1pt.: treatment ( onsiJ1.:rn1ion 'lhould he gh en to encrg.) cflic1ent technologies and prm.:ticcs and tu

t:lfo .. icnt u-.;~ ol rtl\\ mah.:riab. chcnm:ab and water. \\ henc' er eccHmmicall) anJ 1cclrnicall) ka-;1hk. dangerous -;uhslances should be substituted b)' le-;., Jangcrou<; <'r non-dangerous -.uhstanccs. ~ lcasurc'i such as in-plant changes. process rec) clmg anJ imprmcJ matcm1I handling anti storngc prac11ccs ma) .1lso be employed w effect rL·<luL11nn in emission-.. .

. , he guidance issucJ in this note in rcsptX"I of the U'>e or an~ lCChnoJogy. technique or slanJard UOCS 1101 prcdudc lhc ll'>e Of an) other -.imilar tcchnolllg). tcch111quc or '\liJ11J,mJ. "hil.."11 may Jc hie' c the s.imc cmi..,.,1011. rhc cntin: range ''oultl not ncu.:ssaril) be

51

-c ()

c fl)

> c CJ.) ..c () 0. (.)

co (..) a_ u

-(]) I.--c (])

0 Cf)

> z w

appropriate 1n specific cases. lhe specilic ch()ice depends on a wide range of' circumstances but the crucial factor is lhat the ~ekcled regime achieves BAT. When deciding the tcchnolog). local Ambient Quality '1orms muc:;t he taken into consideration

In addition to prO\ iding for the installation of equipment and the operation of proc.:cdures for the reductton of possible emissions. RA r will also necessitate the adoption or an ongoing programme of en"1ronmcntal management and control, \\hich will focu-. on continuing improvements aimed at prevention. elimination and/or progressi\c reduction nr emissions.

\\'hen t.lctcrmining best availahle techniques gi.;m.:rally or in spec11ic ca'>cs. hearing in mind thc likely co~t.5 and bcncfns of a measure: and Lhe principles of prccaut11m and prc\cntion. account m~t he taken of:

lJ lite use of low-wasrc .technology, 2) the use of less hazardous suhst~nccs, 31 1ntroJucuon or recovery and rccycl ing nf suhstam.:cs gem:ratcd and usc<l 111 the

process amJ of \\astc, \\here appropriate. ~) l:lllllparahk prm.:es-;e,, facilities or n11.:Lhods of opcraLion which have been tried wtth

'UCCC\\ till an 111UU!itrral "Lak, 5) tL·chnological at.l\·ancc.;. and change' m sc1cntific knowledge am.J understanding. 6) the nature, cf lcr.:ts am.I volume of tht: cm1-.s1ons t.:Dm:erncd, 7) the commissioning dales tor ncv\. or cxis1ing insiallatinn">.

8J the length of tune m .. 't:dct.l to introuuc.:c lhc hc-.1 available technique. 9l thc t.:11nsump1ton anti m1tun; of rtl\\ matcnab 11ndutlmg water) u-.cJ in the prucc ... ~

am.I their energy cl tiricncy. 10) tht: nt:cJ fl' prevent or n:Jucc to a minimum 1hc i\\'crall impact of' the cm1 ... smns nn

the Lil\ imnmcnt and the: n~b to ii. 11) Lhc ntcd to prevent accidents and to minimise the: w nsequcnccs lor the

environment;.

lhc tcclrnil.fucs :ire regarJcJ .is n:pn:sc111ing B \ I for a uew actfri~1· I ltmcvcr. it is al'o gcncr.ill) intcm.kJ th~h t!Xi\tiug jtu:i/itit!.\ \\j ,I progrc!:>s 1lma1Js allJlllmcnt of -.imd.ir cmiv.;ion '\lam.Jard-. (I ~I. hut lhl' ..;pccific f-1 \ ' rcqmrcmcnt-. and as,ou.itcd time lramc-. \\ill he tdcntified cm U C<.l'>C h) ca-.c na,j, \\hen the U\llSt:lll ;1prJicalion IS heing f1WCCS~CU

f.urthcrmorc. for all .fuc'ilitii.:s. udditionul and more 'itringcnt n.:quircmcnh may be Sf1L'cilicd on a s11c-..,pedfit.: hasis ''hcnc\er cnvironmcnl.11 protcc1inn '\O rcqlllrcs. l lcnc1: tht: B 1\.1 g.uidclim:~ arc not the -.oh. ha~i.;, nn \\lrn:h ct\nscnt::. an~ In h~ grnntc.:d. ~1ncc nf(lrmution from 11Lher \OUrcL~ anJ kga \d.., \\ill al-.n bL consiJcn:d. including ... itL'

!- p~·dlic 1:11' ironmcnt.il JJ1J lcLht iL:.11 data. and •llhcr rdc\ ant information.

5 . .3.2 Bt·, t \\ailahk Tl'l'hniqut·-Sulutiun~ (B,\'I .,)

c: u

O'.) (.) a_ 0

-~ ,,.._, c Cl)

(.)

(/) -> z w

In order ln a\oid llll\\antcd ad' crsc impact un the cm ironmcnl from the plating :11.:1h itics. 'm il'llS c1b:11cmcn1 mca-..ures can he adopted. \\ hilc man) industrial unih ma) ha"c nln.:ad~ impkmcn1cd \'nrious solution-... ro a l:11gi.: ..:\lent 1hcsc so lut ions can he rcli:rrc<l In a-.. COil\ cn1io11al 'ululinn.

I he tun!h11ncntal :ipproac.h 111 achic,ing BA"I irnuhc:. fnllo\\ing impnn:mt con,1dcm11on,:

• all ''a IC'> arc to be con,idcrcd a., unusl"d nl\\ materials although a complete non·\\<t".llc ~olution ii; not rcali~tic

• 13J\ r might be applit:d in the thrC'C kl'~ areas good h<n1,ckccping prnctic1:;, imoh mg \\orking hubi1" :md attilutk" h:chnical modification imoh ing m11dilic.1tions on existing ma~him.'r). proccs~ modification inV<1h ing suh titution 111 chemicals and ahcrnath c pro c-s~-=::-

• BJ\ l n11ght be applied at di ffcrcnt le\ cb of sophi-.iicatinn: lmmcdi.uc application nppl) mg l<m-tcch mc.1:.un:s Intermediate appltcation appl) ing mL-<lium-tcch measures \d,,inccd upplicatio11 appl) ing h1µh tcch mca-..111c'i

• B \I lll•.':Mlll'{:-l n11i;h1 hl' applied prog.n:ssi\ d~ i ..:. singl) or Ill cn111h111.11111n a' ">Ollll' 1111,:asurc' require:

no signi lic:ant or little ill\ c:-.t1111:111 hut 111.:..:J more org;1111sed \\ork111~. denning and heller supen i~i1l11 "1th mui ntc1Wlll'l' '' hik other mca,urcs nccding cnn..,idcrnhk· i11\c-..t11K'l\I in thl'. fo1m t>l'adJitinnal cq 11 i pmcnt

H1\ I 111 ight l'l:sult in:

• l'l'lhtl' I in11 i 11 rcsn lll'l'l' co1i:, um pt i1111 11 I' \\alcr chemicals cncrg~ ( dcctn-=11: )

• rcdm:cd .111wunt c11w;:.1nn 11I: ""'ll'\\atcr cn111mm11g ~hcm1c:11, sludge :111J 1llhcr \\:t,lc t: P'-'' .1ir cmis">inn

• 1111pr0\cd hottom lmc in tl.'rm' ot· reduced pmduclion cost..; impro,cd product qualu: cn:dibilit) and compctithcnc''

-· c . 0 c . (/) ·-> c: Q) ..a 0 a. 0

~ ...._ CXl 0 Cl.. 0 -Q)

s.... ....... c Q)

0 Cf) -> z w

.--.. c t)

c (}) .> c: (1) ..c <..> Q_ (.)

~

~ -ro (.) 0... (.)

Q.) ,_ ....... c Q.) (.)

(f)

> z w

4.3.3 U;\' f hcncfif\

S.3. ~

rhc fnllO\\ Ill~ l'x:nelib might he e:-..pcclcd: • Minimic;cd risk of pollution in C\cnt of an·idcnh • Minirni~cd chemical c:-;posurc of cmplO)CC:) • ~linimiscd consumption of chemicals and ''ntcr • lmprO\ cd pcr,onncl morale due to healthier and salcr ''ork em ironment • Prnduction-dov.ntimc pn:H·ntion or reduced scrap production caused by

improper choice of materials. insutlicicnt programming facilities. bad mailllCl1i.UlCC of equipment or had conliguration of the prlll:\!SSCs

Gl•ncral HAT approach

\, · 11c ::cncral BAT measure~. '' hich arc rdati\ cl) simple and cas~ to adopt arc •. unmari/cd hclo".

Tahll' ·t t: £nmpk1; on general HAT mc:"u n ·s "ithin clccrroplatin~

c:cncr.11 { , . \lc;1wrc'

• < kaiur m.unh."ll.&IK.:

\ k 1h1ul

·1mrm\,,. ck.111111~ .ind M:unte1unw

Hc n cftl

1•n"l1mr:ro11 ul d1.-intLill~

.nl<l L,terl'' (lk."'JI nnd .:ln;11,11~ I

------------------------------------------------------• :\ppmp11.11.: ~turnt..: 11.1\C p;1' .:11 .1ml "hi:ltcr.:J '"";il!.: M1mm1~ n,J.. ol 111 c.:h.:11111::11 drun" \1 llh d111111' ~t:ii;kcd 11111 1111111: lh.111 • d1.:m1l1tl n1111u111111a111111 01· ~1ul

• lnsul:i!c Ml (lnx:o-.. t.uil.s 111cl11Jmi: (ltpmg

~ llcl"l' uml 10 :illo\1 frc ... 111111.:111~111 ·spill.ire 01110 llooi of1h.: lnrl hl1

l sc 1.hcm1~~1 r~1stm1 m.111:ri;il

-----------------------------------------------------~ • \l.11111:1111 t:li.:11111:.11 L l~l' l1md11.:1111t~ mo:tt:r' l<1 ~1111\\ • ,\1111d, h.:1111,·al dq•l.:111111 cmi.-1111,111<•11 m 1111.:11111 "'I' up chi:111i. .• 1h tlu.· h• • l'r.:1 cut"' .:HIO'l' (11 .:hi:m1 •. 11, JlbllllJ! hath'i .11 l>..11!rt1t•ll UplllllUlll l.:1 el

------------------------------------------------------• lnlrni.IUL'C d11r r11.ml I o;i: .:hi:1nin o;h.1fl\.'tl 1ldkc1111 .. Ill • ,\1111cl "'r1ll.1gc on1t1th.::1111111

b..:111,·,·11 ad1111.:c111 rc111rn \1111!!·11111111 d1.:1111l.11, h111ml • lk1.11\.:r~ 111'c.:hi:1111t:;il drip' h.11J, lank' h.r.:~ 111 the rdc1111111.111~' trlln r.:11.·1 ant 1.111b

-----------------------------------------------------~ • R.:1d.1.1.• \\t•m·out I ',c pJ.i.,111 l.IOI..' \\lt1d1 .uc • l'rt:\l.'lll ChL•1t111:.1l l.:.1l<:t).!O.: I wnk' .uul lc.1!.1 r•r-" r~1,l.tnl II• L'llrrl1'11lll • R:..'llucc \\;"llC1' c.nn~lllllflllC•lt

• lrtt.:r.:.1~ hli: 'r;t111•l 1.tnh

------------------------------------------------------• "Pr.t) rm~illf m ~mall ln~1all \\Oler ptJ'I.' 1111h 'I''•" · Rcdu~'\: c111NllllJll1tm ••I 11.11.:r pul•l.'' novJc, l•lcr 1h.: rtrNng 1,1111..• • l<cduiX 111~1.11 dr.11! ... •ttl

11 herein \\ nrl.. p11:cci. :m: "ftra~ c•I Junnll h111 .. 1mi;

-----------------------------------------------------~ • Rctt:ii.• rl.tlm!! rorrds l ',c 3tlln i1111trolkr In i:lll."1:1 Ilk· ';h.!J,..: 111\ Jr.1g .. 1111

f

,1! 1np ('l"lllun !{111.1111•11

: A~1Pi ~117'tl1ik- - - - - - l ~:: -.. ; ;n~1.;11i7c -.1;1.irll ;i11~1r' iu7 - - -. R-7d~L~ Jr~~•~t :,,-=- - - - - - - - - - ... C:t•Urtli:r·fkm fllhlllc Ncl·lilltnl! h• rr.:1 IOU~ fl!Nllf! tan!. dtCrtlli:.11' llqmJ

II :uuf had.·lillmg tn 1111h • "i.iw 11~ olfr1....,h 11.n.:r pl:tllnl!, ha1h • ml.:1 .111hc '"f' .11111 • 11...,, i:n•s' eo111mnrn:1t11>n

• <1111k1111 the hot111111 0..1111..-.:11 1:1111..'I l'ri.:-..:011.11111111 hir h.11.:l..·lill1111! '" 11~· nl

54

I General ('p '.\1easurrs ~kthod Benefit

de-iorn~ \\atcr

Ll~ lc1~s~.;-o~ poly:- - - - - Pl;c~ ;uili;1_;-nt pl~11Z ~aiis-;,; - - - - -. R.;d ~c~ ~h~n~ic"°al-c~aP.~ra~tt;.,1,.:,- - -1 pmp) knc: l>;llh m hot c:mcr the: \\hole \\atcr '11rli1cc • Min11n1,c hc•ll l•h'

j prm:c'' tanks Arca 1'1c\cnt 1111M h•m1Jt11•n

t ; l l~a~1 ~11~t;1;t ~1i~1t~ - - - ~tiol1,J) clc'31; b; ;.~~ ;, -:1~.:l - - - - -. j":,~,~r; ~~·<~u -.:l~i:trk.J - - - - - - - - 1 .111J hu,b.1r' Bru'h C•'nm:1.:ti11n'

• Kccp liushar~ tr..:.· fmm ··..:tu:mu:.tl .:.1i..c:-- and u11\\;i11ti..'ll cn.1tmg' I

• Rcdm,.'\: dc:clm:il) .: .. n,untpll«ll 1 I · hnprnh' plJlln}! 4u.1'll)

·--------------- - ------------ - ------ -------- -- --------~ • \fa1111;un r.1d, <:11;11 all parts .c\cept th.: dc..:tric;il 1\\n11l 111111c .. c,sar) ln,ulallun c•1ntac1 puints. \\ith dH:m1 ... il · .:<11hl11nptiu11 ur l'l.11111}! llll"l.11 j

re'1~tant pol) m.:r. I he <:uallnf! • pbtm~ •ll tli.: r 11..b :.hall~ non-porous :ind\\ 11h11111 • u'ag..: 111 dcr.:trn:ll\ Im 'ul'pht' Cmcl.s rt;t1111g

Note: CP indicates Cleaner Production

Figures 4.1, .i.2 and 4.3 schematically depict the application of BAT tcd1ni4ucs

5A Specific BAT approach

Ideas to implement some specific BA r measures are ~ummari?c<l h\!rC\\ ith un<lcr the heading of: • pre-treatment activit) • plating activity

SA.1 Specific CP Approach in Pre-Treatment

Table .i.2: BAT approaches in pre-treatment

Applic:1tion in Prctrtarmcnt

Prc·ck<111mg ol -.mall s11c W,lrl, p1cc~

\ltthod llcnc:fit

· Reduce: lcn~th~ pr..:-11.:01tm..:111 L'se n cen1rifu11c w r.:mCl\e ;ill dirt prior tu dcgrca.,1ng ru: 111 1m~1sc

clean I mco;~ requirement onto the d1cn1 (medium tcd1)

• K.:dun: cl.:ctrictt) c111i-u111pl11•11 111

wrfoc:c 1m:pa1;11inn I I

r R~-m~1;al11T ;;cuu1~hue"J - - - - - C1s~ ~c7nritl•!;c: ln~c<ln7~1~.:h1- - - - - -_ R.~.i;;~ ~n11'1t~;1l11~n 7,i:·i.np;.ri1~: - - - - 1 1 11.ind i:;n::hc: 1umk~1r;ihk ~alt' and orcam..-,

I . inch1d111J! nil ,uu.l )!rcasc j in J

tkl!r.:a~r t:inl. • l'rolrn1~ h i ~ ,-p;1n 11J dc~·r.:-;1sc:t hath

I l' ltr;;.1~1t~al11;.171 t:-al-1.;li~<'- - - - - ~cl1~:.;p[u;aw~ {high 1~cl1I - - - - - -.<:. ;i-~.\~ - - - - - - - - - - - - - - - - 1 Dcgn:;Lo;cr hath for inlet wmer

------ ---------------------------------------------------1 I ltr.:i.wnic Jcgre•i-ing '\dt:c,pla11;11oi: (high 1cd11 ,\~ .1Nl\t: 1

55

-c (.)

c . (}) ·-> c (1) .0 (.,') Cl. u

co (.) n. ()

~

(1) "...... c (1)

(.)

(/)

> z w

Electroplating Work Step 1: Fig. 4.1

Electroplating Pre-treatment - BAT approach

Legend : ~~~~~~~~~~~

'J• ~

• . ............................. -........... ---...... 1 C Barrel Rotation

I Wot Scrubber r· .......... -. .... -.. ~: ! Vnpour I lorn l .J Spray Rinse

i l. I /I: cx:x::;o Tons1des or Polypropylene balls

WWTP .) ..... J i ~ ) : ~ i ~ ~:t~l:~~or Trea•rnent Plan

l Workpiece ! --+ Worf; p1occ flow direction Dnpp1ngs !

wo•••'oc• now ···· ··········r~···-···· ;···~T;··········:··~r····· ····tJ~r······c·aj········ · r. Pl•h•g

! ~ c ! ; l c ; i : c I ., fap wmor of

i • ~ ... . Water lrom ~ .. ·. :, .... ,~ .._,..,_,,.._,,.._,,..__~.._...... ... , . ~-· ... _ ... _ ... _ ... _ - - _..._ ......_ ...... _ ..... _ - ..... _ Reverse ~ ,: ~ ' i · Osmosis Unit

60°C ~ : ·~ socc • 8 23cc ' : • , ~ ; • 1 • (11 any) ~ : : ~ ' .

, Alkaline ~ : :~ Acid ~ l · Rinse 1 Rinse 2 ~ ~ : : ~ . ~----·---•.,•, ---,.."•,,~ : : ~ ,,,, "' '.\: '"'''''\: ~' C\'\: ~ : : l.AL . . 1 : / · ··l. r~=:::;;~~ ············· r~:;,~;.:~~·I

Hoal lr1:.ula!lon • • y .............................. _. __ . .... -.. ·-····'

T lfiNi/TP

Waste

r

en () 0.. ()

© ..... +-' c (!) ()

(J)

> z w

Vt ... 1

Electroplating Work Step 2: r.. 4 ., ·1g ....

Plating Operation - BAT approach for Nickel & Chromium Plating

Legend :

Workp1cco !low from

. . ... ................ . nocovorcd Me1u1 llJ1 Cul

Rinse 1 Rinse 2

:............................. To l/'l\'l/TP

Bnrrol Aota!lon

Spray Rinse

lcnsldcs or Polypropylono balls

Drip Gunrd

Work piece flow d1rcc1ton

Rinse 3

'

L t loat lnsulalton

f'!Qt~ Ctiamica' conc13111rat1011S in

plallnJ oath sho\i~ be ma n1a1nt'd at op:imum conccntmt.ons

,,..-.., c: (./

c

en u a.. u ~ -c <J)

u Cl)

> z w

Electroplating Work Step 2: Fig. 4.]

Plating Operation - BAT approach for Zinc & Chromium Plating

Plating

Legend:

Barrel Rotnt1on

Spray Rinse

T ens1c.Jos or Polypropylena balls Drip Guard

Evaporator~ ~ _. Work piece flow t11rochon

Rinse 1 Rinse 2 Rinse 3

~Qlll... Chomicnl concc11tru11ons tn p1.111no l>nth stioulcf ho rn11in1111nod at optunum concon1r.111ons

Ol () a.. ()

a> ._ -c: <D ()

(/)

> z w

for 'isualisation of some of 1h~ applica1iu11'. sec ~·une illustration in D1 .m ings I. 2 .ind 3 al l!nd ofthb Section.

5A.2 "ipcdfic HA r i\pproach in Plating

l':ihk 5.3 :-.ummari-;l!s flAT apprnuch in plating.

Tahlc 5.J: B \ r approachc' m platin l! linco;

A1•Jll1c,1111111 m l'la1111l!

\\ .111..'1 O,m l!ll..'1Cr _,J l lllltllldl\ II~ JnCl..:r

\.h:1h11d

• hnr11dm.'l: on·hnc: 11.,,, meter 111

\\,lll'I llltill..: f'l(X'

• l111ruJucc on·lmc \11mh1d1\ 11) mc1cro1n JlffiC'c!S:S umJ...

lknclil

\\ :ncr ),11 •n!:!s lrum cmr.:1..1 .10111~1111.:nt Ol - \\3lcr fl,>\\ 11110 l;ht lllL...: t.1n.I. • Jllalm~ chcmn::il rcpkmshrni:nl

-Re1~~~•sm~is1~-1R61 ~.;1;~,- - - R<) 1-:. ~oi ,;,;,;;;~ •. ;1di:d 1~.r~LZ.: ~n- - - -R~Ju:-c ~n"ii1ir.;11~·n-oi ,;,,ru;1~c: - - - - - -Rins.: \\nlcr for mlct \\Jlcr '~Slo:"m~ 1\f1i:n: cundcssr;ihk )J]1s and urganu:~l 11110

·pl I " 12· I I ur rll 1s 11-~ rm .. ing 1.1111.., • 01g.m1u 111inll11i:1111\Jll.'1 ~ {! I

t-, ~nZ r"iaiu;g - - - - - - - - - - - r1;.r ~' i~rnh~r ~c;,-11; 1hc - - - - - - -R~du:-C ~.~,;u~1Pi1~-.. i ,,-11~ - - - - - - - -

pl.11ml! ~th I he mlct Jl'P..: .111d bacl-l11J111g pip.: is 1nst.1!11.-.l 1111h.: I prrccs~ t.lnl

r -,~ .. i:ci. ch;u;~. ;o-pr,:; ~d- - - - i<c~.;, ~, i1e"".i1~ ~n~ml; r;-;1~1 ~.;;J - - - -. ~~ ;;,i l~· ;.l\~ ~i:71tt1i1; - - - - - - - - -, 110 platmi; ""''"!? 11.:itcr for remc 10 plntmg • lkducc: nmounl ot "lmlgc:

I h;tlh' b: lllC.tll' Ill .:k~u .. 1~"" 1.c:ll • lkdu...: COll~'\:'lllfll1U111~ OI hCa\)

L

5.5

or 11.J!l c\chan~c:r 1.mtl .:1.1porJl1un mct.!b en \\~C\\Jlc:r I un1L 111 ... -quirL-dl - Rcetl\ er hc:a' ~ mi:tah lur rc:-u'c or

'ictondar~ ra11 111n1cr1.ih It• be "'ltl 1111

Potentml initiati\'(~S and co't c~tim:th:'

fhc bchm tahulation gi\'cs an it.lea ol lhc di ftercnt cost range relating to the various ini1ia11vcs It b to b~ nntcd that the cosh nrc broad e!'>timatcs uni).

........ c: ·-· (.) ·-

en u Cl. u Q) ,_ ...... c Q)

u Cf) -> z UJ

\11ph\'11 l11hl\

I 1m-11:.t1

·~r...11~

\kJ1um-11.1.h

I h11h-1ccll 111c.1'11re-.

Tahlc SA :Pott·ntial 'o lut ium '-l lltl co~I l''limatc'

ln11ia1i' '' I \\ ti1111\

• Ck.mm!,' t m.unt.:11,1111."C

• Dnri ~u:uJ (p1I~ ('Intl'~ kt rl.t\11\. lllJICll I) 0.."fu~n t.i:tl'

( "'' ll.tn l!t' in fl\

1':.:i?lig1hk

-------------------------------------------• hdt.:rcJ ,1111.1!-"- h11 th1.·n11nsl drum' ''uh "eJ!lil!thk :.econ~ wrn.nnnu:nt hut \\1llK1111 i.l1J111.1~-..·

• l'ul .iu l-lu\\t'I 111 ~"fl.II.th: .:11d11,.111.:

lh 5.IHHI

-------------------------------------------• \lul1tplc .. 1•unh:r 1l1m m ~ n~ "'tllt.:111.• I<.. 111.1100 'llOtMI

• Jl.un:.I rut.II •lfl • 1 .. lt•I' P"ll 1111 •

• "p1.1~ nn.-111 •

• ( cmnlu!,.: quc-11.:.11111.:1111

• lntrci.11.J-'~'1: 111r11•\t: •.1p1111r •olk\.lmu homh AnJ x"lllhxr "'"m

• I ltra liltm111m I l11,1'ijn11~ ( p1.·-11.:a11111.·1111

• Bad, 1ill111;: h• pl.1111111 h.11h~

• l:'·'P'''·''"r h.1th .111.l ,1.:111.11cd 1..1rho11 lih.:1 • Fk..:trul~ ,1, 1.dl

lh_ I .IHIO '5 JIOll

R.'.> 70.(KIO - I (Kl.tlUll

R:.- 'i0.0110 • I .50.flUll

lh ~11.000 3.00.000

·~ ' I.I l1J.clllll

lb l~.001) I{~ JO.IHICI

~11.11011

1.110.111111

lm:lmh.:s construcuon and inst:tllalion nl' electrical cn111.11.:1s for opcr<tlinn rned1a11 ism~

~llll' . 111 ,jc,, of the ;naih1h1lit) (Jfdi1Tcrc111 design' and systems. the 1.kt~1ils ol l.'.o't' can 'ar). The industr) i!- cncountgl·d 1t1 acquire the latest co:-.t in~1rmatim Imm the equipment supplier if an) cleaner production initiati\c in the ah11n· b tukcn up.

='·h \\ a'll' Treatment Option.'

.\n dc"·1mplating unit generates 'ariuus ~trl.'am~ of liquid \\astc. \\hich require dillcrent 11catmcnt l(:chniquc,. '-,uch separate treatment (often pre-treatment} 3\'oids the possihilit)

. 60

,,--.. c: CJ c en

:5 c: Q) ..c () 0. (.)

~

~ -co 0 a_ 0 Q) lo...

+J c: Q) ()

UJ

> z w

\lr 111i .\ing i111.:0111pa11hk \\astcs. \\hich make' treatment Jitlirnlt. c:-.pctbl\C and k:.-.~ rcli~1hlc. < >fte11 'uch 1ri,ing can he u hatarJ to ~N,nnd or formation of complc:\c.; that me dilfo:ull to 1rea1. :.-.ud1 as mixing ol '-.1ckd plating \\a,lc\\alcr "i1h t )aniJ1: hearing \\a,IC\\atcr leading t• IMr1~11io11 ofN1ckd (ynnkk. ·1 hcrdiirc. 'cg1eg:11ion of\\:tste\\:ttcr '1reams is or paramnunt impnrtancc. During the in-depth slllJ~. it has been noted that in m:.ijorit) of sm~ 1 1-,c:.ilc and tin~ unib. tlfr.; is ju ... 1 1w1 Jone . i11dica1in~ •111 ur~cnl necJ to in1tothK1.: 1his h~hlL rc\.1uircmt'nt

1\s a general rule. \\,htc \lrcam-. an<l d aracll"r ... 111..-. 111u ... 1 be carcfull) i:\aluatcJ bcli.m::-'-·lectir·· ~: trc.111 L'l l '1..'1'-11c 11 \\.!" h·und dur n,: the stud) that units in largL' anJ mcdiun s1...1k ha\ e 1ipt1.:d li)t tn:atmcnt ::.chcme-. that C<1h.:r l~1r their parti1..·ular \\a,tcs. ·11tll\ir1gh thcr ... · 1. ,1 1..nmnw1Mlll~ 11 treatment mt.:th11J ... and 'or proce::.'c' uwd. In :-;11111c 1."1rcums1~111cc,. (l'.g .. in Bangalore). it j, liiunJ h• he ec\1110111i1..·al. pr:ic1kal :•nd much heller managcJ 111 h,t\C .i L'1.:ntrali1cd '~·'''c treatmcnt facilit) n1wra11..·d h) :i -.q1;1rat ... · c111it) . In l~tl'I it is a \\clL'rnni.: dc.:\ clopmcnt 1ha1 in nWll) ... talc-.. i11du.;1rial \.''\l:Hc' a•1J p;irl-.s ar1..· coming up to -;hift e\l'iting umh and acct'fllllllldate in a propi.:rl) 11rga11i,ed grour or clcctroplating uni ts "iLh ·' CFTP ( C\ampk Faridahad in I lar~ ana. \ bJrn Ii Ill

I :.imil "\,1du. 1\11and Parhac ar\.·a in Delhi ctc )

S.<1.2 P rincipk' of Trl'a tmenl

l\1r 111\ist hca\) metals. prcupitation as in:-;oluhk h)Jr,1\) \ll' sulphit1..· Ctmlpound" I!'>

nchie,cd h~ addition of s11npk reagent-. folhn\cd h~ pl I aJju:-tmcnt :ind 'cdinwnt.ill, l Ir thc c:.ise ot' he:\:naknl Chromium. it j, 11cci.::-,ar~ lO lir't chcm1i.:all) r"·Juce the mct;.tl to tri\ ah:nt state anJ then form itN.1 1blc pri.:cipitate .... 11 O\\C\ er for ccnai 11 'er~ h.l/ardou ... hc;.I\ ~ mctab such as Cadmiu111. a total I) 'cp;1ralc '' .... tcm m:l\ he ad,antag1.:ous. including !'-cpamtc dbposal pwccdun:'

\\'hi.:~c 111e ., :i..tc\\.ttcr contain c~;.rnidc.;;. remO\ al or C) anic.k-. i' a<.: hie' cd b) o\idatiun to hmm le...,, ri.:s1Jm:s. folh1\\cd b)' a prcc1p talion 'tcp to rc.:mo\e acel1111pan) ing soluhlc met.i ions

It i-; impon.111t 111 Jistingui'h hi.:t\\l!en trcmnwnt ol' 1in'c \\~Iler (high 11<}\\ and Ill\\ conc ... ·nlnllion) aml discarucd strong process solu tion'> (cleaners. aciJ dip,. plating ~t1lu11011., etc J ol lo\\ \'Olume and ~ml~ occa.,ional discharg<.: but of' high conccmra11un. Clearly. a hatch lr\:t.tlmcnt S} slcm \\ ould cope \\1th [\\Cl l~ pcs or\\ ~1-.IC\\ aler rJthcr than J

wnllnuous llO\\ ")stem \\ llll:h '' likd~ lo he up,et h~ slmd, loads. The guiding pnnc1pk is to store such strong \\a-.tes and rdca.-.L' them graJuall) 111tl1 treatment s~stcm l~ us ll<m equali<;Jl1on is an important op;:rauon to intcgrati:- into the treatment ..,~stem.

5.6.3 I rcatmcnt PrnCC\Sl'S

5.6.3. J T reatmen t of Hc"\a\'a lent Chromium bearing \\ ~htC\\ ater. I k:-.a,31cnt chromium compound-; come from proccsscs -.uc.h a:-. polbhing and brightening. pickling. passi,ation. dwmlL plating and pla-.t1c mctallis~11ion . Kcduction of

61

--c u c

OJ 0 a.. 0 -CD "......... c (])

0 Cl) -> z w

Cr(VI) tu the more easily prccipitatcd trh a lent :-iatc ( rather 11011-tm:ic) can be= achic\ ed n rmm~ \\rt~:..

Sulphur compounds are common!~ emplo)ed for the rcduclion of hc:-;a,·alent chromatcs. t\dvnntagc:> indudc !>hort rcaction tirnc:>. the ... irnplc ob:-.ervation of tht: reactions b) mca.,uring rcdox potential and a lo" )ield of sludge artcr m:u1ralisation \\ith ~odium h)drm.idc. I he ulphur compound include (i) Sulhur-di-o~idc gas. di-. ... ohed 111 solution. (ii) mctahisulphih.: ( :"\a_ "::Os} or nllrma'I sulphilc (r-..a. "O ). ·1 hcsc compounds. m acid ~olution (pH range~ te: .3 J. dissociate and the bisulph1ll: .inion ( 11"0 -) rcdu~cs th.: Cr to the tri\ <1knt slate:.

S1orch1,1mctricall~. for the reduction of I g of Cr (VI). 0.92 g ofS is rc4uircd. From tlli-.... th\.~ 4uantitic.:s of the appropriate reagents can be computed, assuming thc reaction quidd) gnc ... tn cnmplction. Iron salts can also be u ... cd because they arc sometimes cheaply mnil;ihh:. I he theoretical requirement is 3.22 g Fe (II) and 6.60 g 11·~0 .. Or 4 91 ~or I ICI for r\.·dm:tion of I g of lr ( \ ' I). Table SA '."ohm'~ the:) idd of hydro~1dt: prl."C1pitation and of di,,uh cd Sulphur salt (contributing to raised TDS) iodicating the burden on the '"°"' 11rn1111c:nt in other form... The high amount of sludge produced b onc of the d1 i:um 1~ing factor-. against u..:.e .\f re sah ;:ind not normal!) usi..:d in India.

r~hk 5..i: t>rccipitaaion of Hydro,id<."' and Ncuara l sa lr 'I from red uction of C r (VI)

Reducing Agc.:nt Yield of Na1S04 Precipitated hydroxides ___ ,_From ncutraliL•llion (kill_ __ as dry ~t_l.tllcr (kg)

~ulphur c.Ji-u,iJc 4.1 I 98 ~ml~urn hi-:>tilphllc: X.2 1.98 Fc:r~l' "_l_.11 p._l_1a_t_c: __ _...___ 16.4 _ ~ .14

Soun.:c lJl\LP . ... l m 1ronmcntal hpcets of the ~lc:tal Finishing lndw·.tr) . A fcchnical (juidt:" Par is. I <)<J~

5.6.3.2 I rcatmcnl of Cyanide bearin ~ n :t"lcwntcr

I ht t hcm 1"ll) nl Cyanidi.! detoxi lica11on "rd.11ivd ) complicated and in most cases. dcg1 ad.tt ion need'.'. morl.! than one rcacl ion stcr

Degradation \\ith Chlorine:

C)anit.ks can be oxidized b) chlorine: both chlt,rinc ga~ and ~odium h) pochlorite can be u~d E\cc:pt in \Cf) large plams. \\here use of Chlorine ::;.i.-. ;s more economicaJ. most plant::. U::>.: Sodium H) pochlilritc. In case of use of Chlorine gas. thc h)drochloridc generated together with h~ pochloritc rcqui res further neutralisation chem reals. This h.:chniquc i~ !>Uitablc if the ( ~anidc concentration rangcs Ocl\\ccn 0.1 and 1.0 g.' I. 1\ ~Ji . tuJ, .mt:igc of usmg chlorine gas is lhc high production of salts from the subsequent ncutralj...ation.

62

,.......... c (.)

c: (/)

'> c: a>

..0 (.) 0.. (.)

~

~ ...._.

a:l 0 a.. 0

~

a> I.... ...... c a> 0 Cf)

> z w

When ...,,)Jmm ll)pochlorite i~ used. there is .i t\\O step proces~. In the lirst step. c~anides arc u:-.1d1scd by hypochlorite to C)anogcn chloride. "•hich is an e.xlrcmely toxic ~as. ·1 he ::.~omJ slcp. \\ hich takes place almost s1muhancousl). ill\ nl\iC' h) dwlysis of' cyanogen chloride to cvanatc. The laner is hi~hlv soluhlc in \\atcr hut care shoulJ be taken to cn.;urc that 1h~ temperature docs not ~xc~cd 4011 l ·. so that dcgnssing doc' not take place. I la1 .. arc.l:s arc best minimized by ensuring as rnpid a h) dml) '\is "~ pnssiblc. I hi.; is achk\cd at a high pl I of around 11 5 \\ith a detention time of upto I hour to guarantl.-C compktc reaction. Gooc.I mi\ing is cs,ential. In some countries the r~:tention time may he set b) regulation. In most cases found during the in-depth stuc.I). further o:-:idation i'rom Cyanate 10 '\111rogcn and Carbon 1s not carried out and the clllucnt b 'ent tn an equalisation tan~ fo r neutralisation. \\here further oxidation is rct1uired. it is earned out hy using <..,odium I l}pochloritc again at a pl I of 8.0 to 8.5. It is very impnn:mt to ha'c correct anc.1 reliable pl I 1.:ontrol to prevent toxic. gas formation umlcr acidic conJititms.

lkg,rJdalion \\ ilh 1\ctivc or Activated Ox\ucn

Oxidation or Cy;midcs din.:cll) using ox~gen h:ads tn a grcat hcndit that no :-.al1' ;-irc produced and nu neutralisation of solution is required. J'hi~ can be done hy u-..ing (i) I l)drogcn Pcro~ddc. (ii> Pcrsulphuric Acid and (iii) cnial)tic o\idation .

I hc1,rctie<tll). 1.3 ~g 11~01 i:1o :-.ullicicnt per kg ol C)anidc. I lo\\C\Cr. 111 pr:1cllc\.". 1:.1 )

cxcc:-s 11.:0: b required to ensure complete reaction and (h) thi:. pn,cc-., ' ' not rccommcndcc.l \\ith lo" initia1 cyanide conccntmtion i.e .• lcs~ than 500 mg, I.. /\dd11um of cataly-.ts or Formic acid accelerates the reaction. cnahling the rm:thod -.ui1ahlt: for u ... c in the concentration range of I 00 to I OOOmgll.

Pcr ... ulphuric acic.I is often used as Oxygen Jell\ cring substance. It hyd1 lll) -.cs to 11.:0 : and ,uf rhuric acid in aqucou~ ~olution. Direct o;ronatinn is another :n ailahk mi:thod. Cu11cntr:ncd p1.·roxidc~ and persulphatcs arc hazardous suhstanccs :md 'hould he dealt "ith ac1.:nrd111gl\ .

When the cyanide \\a-.tc is concentrated. an economical solution for dcgracfation i..; eh.:ctmfy,is in presence of chlorides () amdcs can be o:--;idis1.·c.I by clcc1rol) tic spli1ting 111" O:\.) gen from h) dro:xidc!>.

Pn.:cipitation of C_)anic.I~

lmn ions form highly stablc complexes \\ith C)anidcs. A prcc1p1tation of di,alcnt ~'r tri' alcnt hcxacyanofcrratcs is possible as a d\!loxificalion step \\ithin the final wa-.tC\\,1tv treatment. But the rcsuhin:; sedimcm is not lit for disposal to a landfill itc • bet..;L ~ acid' or photo I) tic reactions ma). under certain circumstances. rclca ~c C) snides from the residue.: <:..m.:h sediments can be subjected to thermal destruction.

_... c (..) ·-c (/)

> c Q) .0 () 0.. (.)

~

~ ...._

c::o (_) a.. (_)

~

Q) ~ ..... c (l) ()

Cf)

> z w

I he popular dcloxilicmion method for c)nnrdc' 111 r;;mall ntl'l:1I finishing plant-. j, still O\ldatu111 h~ chllirinc. t\d\ anmgc ... arc lhc speed of rcacllon. l'asicr procc!>'> control. lo'' co'\ls ant ,1 rclati\\:I) long .:.'\pcri.:nl'c 111 handling.

h>r cnnccn1r.1tcd \\.l-.tc'. prccipit.Hion .ts hl'XdC) annlcrmtc is :.unahk but must tK· follli\\cU h) lhl•nnal degradation.

Perm,)- compuunJ.., h~l\ c the general di~tlh .mtagc ol long rclcntinn lime-. I hc-.1. pro\."c scs arc u l'ful onl~ \\hcrl.' 'm~1ll quantitic' 111° l')anidc bc;iring ,,a-;h:\\alcr-; arc tu h1. treated. I l1c content of salt:- in the ctilucnt b km

I 11 -;urnmar) . 1 r c~ aniJc-. arc de:-. Im) cd in in a l'nntimmu' llm\ stream. h) l'k)t:hlunll treatment ma) be the bc~t dmicc ht.'c.tusc of its -..11npk· handling and other mh anta~c.., .1

mcm1011cd lx.-forc. If con~entratcd or 'rnnll \ olunu.:' arc ln he treated. tcdm1qu1.·' -.h,,utu lx· clwscn "hkh ) idJ n minimum nf \\ J...,tc c\ en r r p.:rfom1an~l· :md m.1mt.:nancc 1..., more com pie~.

S.<,.3.3 ~currali,ation and Prccipitarion

I his princip.tl opcr.ition in the '' a:sll'\\ .11cr lrcatmcnl ,., inlcnclcd to con\l'rt d1"oh c1:

llll'lals II l insnluhlc h) Jrn.'\iJcs and rclllO\ cd rrnm lhc d lllll'lll. The ore rat ion i' pr~1. <kd h~ rlll\\ cquahsat1<1n J .111 c~..,.:nllal st.:p. 1 he p1cl· ipitati1111 chcrnicab llsl'U arc ~ Jiun I l)Jni\it.li:. Lime anJ '-,od.i. ~ l a ·rll·-..ium h~dro:-1idc is ~11111cti111c' u-.eJ hut lhl.! n .... 1..111 n 1 ~k)\\c r a11c.l pl I range 1..., l11nited \ll..alim.' \\a-.tc\\:itcr'i arc 11cu 11 .di1cJ hy sulrhuri.: al' ld hut it has <I COl1'lraint Cor ~ulph<tlC lim it..., I I' !->i.:I ll~ 1.·l lllll.!lll ~l<tll<.Jard limallct facilitics ll:-1.!

"nd1u111 I lydm:..n.lc solution ( 150 L1tl). I lm\l'\1.·r II lhl \\'.l..,IC\\,tlt:r l:Ollla111-. lluonJc-. l.1 1m: s11l utinn -;houlJ be u .... ed I 1111i.: -.olutwn 1-.. l Ill' 1pcr a 11d uscd h\ larger u11ih \ 111111.·

"olu1i1111 pn:pa1.111011 unit 1s rl·q111rl.!d 111 till l.1tt1.11. 1 ·l

I h1. 111,1111h.'11a11cc ol'currcct pl I b C''il'llllal fo1 cllkic11t pr.:1.·ipitali1111 ol'mc1:.1I h~Jro\tdc-. Fii! SA '111\\" the pl I rJngc' liir prcc1p11a1i1111 ol s1.'\l.'WI metal h~<lro\idc,. I 11r 11111 .. 1

'-''b" . 1)! I \\Ould be in the r:rngc ol 8.5 tn 11 . l nnc:ci::.-..ir) high pl I ma~ intc:rfi:rc \\ 11h lhl· limm11i11n or n g<lOJ :.etLkablc .sludgl.' I hcrcforl'. lhl' h1.·-..1 prJCtiCl' i~ ll1 maintain .J pl I slight!) nhnH• minimum pl I \ah1l'. I urihcr .1djti...11m.:111111:.t) hl· rcquirctl in case of <>pccilit ernuc:nt standard.

Ba~cd 011 the lr~almcnt technique-; discu,~cd aho\ c. a l) r1cal \\.1:-.IC\\atCr trl.!atml..'nt plant for .1 unrl doing l'r ~i plating and a lilllc Zn pl.11111g u'ing L"~anick i'.11 procc~s can he ik:s1gncd and co..;t c-.tima1c-. made. I he capital rn'l or '\uch a unit i cs Li mated at R . 2.16 lakhs. I he operation t;:. maintenance cosl is c"1im:1h.:d al R ' · 1618 per da~ or

-· c (..)

c Cf)

"> c <l> .0 0 0. (..)

~

~ -al (_) 0... (_) -~

+-I

c (J)

(_)

Cf)

> z w

pH Pb < l m/1 Cd < l m/1 N1 < 3rn/I Zn < 3m/1 Cu< 1 m/ I Cr < 2m/I Al< 2m/I Fe < 2m/I

H reQu

~ Prcc1p1tat1on rang~ wr:h NaOH f' '; .. 1 Augmented prec1µ1ta:1on us;ng lime o· 'i~;; f:-::-'i Common pH reQurremcnt for crsch.irgl' :o \".J;c·s \ .:...:..:..:..

Figure 8A: Hangc of pH for l'n•cipitatinn of ~kta l Hydruxid<.·~

en (.) a.. 0

~ -c: (].)

0 Cl)

> z w

..--c (.) ·-c . (/)

> c Q) .0 (.,) 0. u

co (..) a.. (..)

-Q) ",._, c Q)

(..)

Cf)

> z w

approximately al Rs. 4.85 lakhs. The cost per kl ClllllCs lo about Rs ~6 per kl. \\hich i' cun-.idacJ rather high as cornpareJ to Unit J. privaicly run l 'I: IP. It i-. 111tcn:,ting to notl.' that co-.t of chemicals alone account' fur 86 - ~su '.' of tolal opcraung wst Clc:arl~. thi' point!\ out to the need ro rninimbc \\atcr am.I chl·mical consumption and mtrodUl:c metal n:c11\\.'r~

S. 7 1Ja7ardous \\ a..stc ... Rufe-.

1\crnrJing tu the Hazardous Waste ( \ lanagcrrn:nt anJ I land ling) Rules. 2002 anJ a-. amen<kd 'idc ~.O. 593 < E) datc:J 2oth ~t.1~. 21103. the folio\\ ing ,,a,te:-. from Electroplating lnduSll} are 1Jent1fo:d and li-.tcd 111 'H.hcduk I of the said ruks

I. t\c1d Residues ., \ llo..al1 Residues

"'rem bath/sludge containing .. ulphkk. cyanide and toxic metals 'ludge from bath containing organic sol\etll'"

5. Phosphate Sludge (1 'ludgc from staining bath 7. Copper etching residues ~- Plaung metal sludge 'J. <. hcmical SJudgc from \\astc\\<.llcr tn:atmcnt

In 1hc f11lh1\\ ing paragraphs. -.alicnl lbturcs of thi.' ntks arc mentioned. For l"l'mpktc 111l~1rmation. 1hc reader ma\ n:l\:r to thl nri!.!inal rules and amendment:-> \'idc lhl" C ia1c11c of lnJia (~:\t1:.iordinary) ra'n II. "'cLlton 3 (i°i). in \\hi<.:h the no1ification dated 20111

:\la) 2003 ha" OCl'll published

S. 7. t Rcspon-.ihility of Waste Gcnl·rator (occupier)

,t\ccording to the provisions of the !'Liies. ever) 111.:t up1cr ol an industrial unit or waste gcncrntni shall obtain authorization lhlln th1.: rnlll'L:llli:U <;talc Pollution Control Board or Com111 11lcc to handle. treat. '>ton: anJ Jisposc 111T such ha1ardou:-. wa:-.tes I or thi-. putposc. the occupier (industrial u1111 gcncrnt ll\l' \\astc) -;hall submit information 111 a dcs1gna1cJ I orm No I to -;ed. at11hori/~lliu11 . I hl .iuthorthtllon \\Oukl be \al1<l for supulntcd pcnod and rcnc\\.al llllhl hl ... ought. Funhcnnon:. the unit shall also submit un :111m1al 1cturn tu the com.:crncd l.,tJtc Pollminn l\111tro l Board or Comm1llc1.: in the designated hmn 4

I he <iccupicr -.hall take all practical !>lcps Lo cn~mc that such \\U'ilcs arc pmpal~ hamllcJ and disp1>~1.xl off\\ ithmll any aJ,cr ... c cfli.:cl~ \\hid1 ma~ result from "ui:h \\asks. I le :-.hall al ... 11 he rcspon..,ihk !Or proper c11llcction. rccl·pti1•11. trl"atmcn1. !'.>luragc and <.li-.p<hul uf these "a'tc-. either him.;elf <'r lhrough tile l1pemto1 uf a facilit).

In C<L"C or rranspon of hazarJou~ \\:isll"s lo a fat.:ilit~ for treatment. storage and di-.pu~al. the rule also prm ides for prm:cJurt. 10 he t(1lhmcd h) the \\:t!>ll! gcncr-Jtor. tran~rnrtcr.

operator of 1hc focilit~ and the \1.i11: P(lllutiun Co111rol Board/ Committee ··~wrJg1:··.

hm\c\ er ml.!ans '\toring ha1.ardm1s \\<L..,tcs for a tcmporar) pcnoc.L al the end nl "hich the h;.var<lou-. \\astc 1s treated and Jispo-.cJ off

5.7.3 Disposal of Ha7ardous Waste

,\s for as the Oispo'iJI facilit) is concerned. the industrial unit not having a ha1an.lnus \\J'>tC treatment and d1spo-.al fac1ltt) or ht.., O\\ll. shJll send \\USlCs to a common I rcalmc11t. Storage and ()isrosal l·m:ilit~ ( l\Dl· l I le shall also hccomc a memhcr or such lat:dit).

I he emus of scning. up of J common I ~DI rests'' ith the 5tutc Pollution Control Board!'>. although tht: ruh.: stipulare ... that ··the occupier or npl.!rator of a facilit) or an) asslltialion llf nc<.:up1cr-; shall he JOintl) an<l sever.ill) rcspo11c;1hk for idcnufying sues for cstuhlishing the focilit) lor treatment. ..,lora!!e and d1 ... posal ol hal'.ardous \\astcs.. Procedures arc clear!) laiJ dlmn IHm 10 tdcnttl) a -.i1c and set up J loctlit) .

·1 0 C11'Urc tran ... parcllC) and m:countabilit) or the Swte Pollmwn Control Board ( ") '{ ommittccs. the ruk stipulate"> that such hoanb or committees shall prepare Jn inventor) or ha1an.lnw; \\::tstcs anJ compile mtonn.uion related to treatment & d1-;po ... al I urrhcnnorc. C\Cr) St;.ttc Pollt1unn ( ontrol Board (:-.)1Comm1ltcc shall maintain a register prm iding p:irticulars of l.lisposal on an) land or premises am.I ... uch register shall be open !'or inspcct1on {(l Un) person intcrcslcd or <iffccted.

5.8 HousckccpinJ! (;uidclincs

'\!though good lml1-.ekccping is a malta ol' altitude. panicularl) the allituJc nf management and shared b) the work.force. tt is more of a nc<.:.cssit) than an option 111 an mJustr) like electroplating, \ ,fan) of the chem1cat... used are ha7ardous and toxic. there ,.., good potential or accil.lent!> lo occur anc.1 the mJu..,lr) po::.cs threats or udvcrsc impacts on the natural cm irnnmcnt. ·1 hcsc factor-. lead to a great need for gooJ hou-;ekcepmg in mJc1 10 ensure health and safet) of all \\Orking persunnd as well a ... the public .11 large. I he huu,d.eeping <:4tll he subdl\ iJcd tnto three main topic': (a) storage w1J handlmg. or chcmil:ub (h) hmtsekccping in production ... hop tloor it:. rrc-ckaning and platinJ npcrations and ( c J htlll'\cl-.ecping o I' rc.1eclS and \\.isles. In order li1r lmusdccpi 11g to he clfrcti\L· <.tnd routincl~ catTicd out. thl' follo\\ing arc e..,:-.c:nttal:

• rv1anagc.!mcnt acccpltng its lcaJ rolc 111 prO\ iJtng safe \\Ork mg condilloib an<l procc<lw e..,.

• Participat1nn b) the \\orkl'lm:c in cnsurin~ ... alet~ at \\otk • l lt:ar allncation nf rcspo11sihtlt1ics for satCt) ;mu health WI'\ ice.., • Sa let~ lrnining and i1hlruc11011 011 illlh1ctt\ln :ind on-gomg • Rcrorting. i1wcstigatio11 and anal) sic; of .11.'Lidcnts :ind \\orking condition'\ • D1:-.::;1."111tn.ttion of infonnatinn on hanml-., and nsk s • Co-operation with lahnur and sal~t) instructtons and re\ tl'W~

67

-· c (.) ·-c (/)

> c Q) .0 (.) a. , .. v

~

~ -ro (.) 0. l)

~

Q) '....... c Q) l)

en > z w

1 n the fol lo\\ ing paragrnphs. brief g.u1dcl im:s an: l'" en for bt.:ller hm1scl-.cep111g:

5.8.1 Slo ragc and llamllin~ of Process C hemic.ii !>

Proec.., ... c.:hcnrn:ab LOns1st general I} or (a) at:i<ls. (h) alkalies (c) deaning agcnls (<.!)metal sales for preparation of hath solu1ions (c) additiH:.., and (I) unodcs. I he basic guiJdincs are

4.

5.

6.

t\c.:i<l..; and alk;ilics should hi.: '>lored scpar.llcl~ Containment hunds ... houkl he pnl\ i<lcJ 1m lhhir to containn .1L~1Jcntal lcul-.ag.c or ... pills Vnlallk organic compounds should he ... 1nn.:J 111 gas light container.., anti kcpl umh.:1 lockable covcrcc.l sheds Onl: authori1.:c<l pcrsonnd ... hall ha\c .1ccc..,.., to th1:sc matcriab. Thcsl.! pcr..,onncl ... houl<l be made •m·arc ol' material ch<irncteristics through training: Muterial S;ikt~ D.11a ~heel!'> (\if\D~) should be dbpla!cd 31 a pmm1m:n1 lm::.1tion. I raming lo pro-..1de aid during acciJ1:nts anJ spills 'houkl be gi' en to de,igna1ul pcr ... onncl. \\hose name., anJ Lontacl dctmb should he tfr-.phu.:1.:d al pn1m111c111 locaiions \\ hercvcr po~::.iblc. solution prcraralion ... huulJ he <lune in lmcJ tanb c.:<mta1m:r" anti trunsferrcd In process huths h) rump., onl) .

5.X.2 I l ousck ccping in Production S hop Floor

Thi., a-.pcc1 i" b) fnr the mu ... 1 imp,irLanl urti' it) in 1hc.: day-tt1-Ja) running of an ckctrnpl<lling pl.irll. G<lotl hou-.ckccprng \\ill cn ... un: ... nwoth production. encouragement Ill p1.:rsonncl and developing a pns1tivc 11ti1uJ1.: among all. ·1 hc..,c can he g1.:n1.:rall) -;umm.1ri ... cd as: I \\\lid duller ;111d unt1J) \\(ll'~ing 1.:nnditinn. Introduce lloor marking to J1.:.,igna1c

areas for mah.:nul •aorugc. 1110\emenl of per.,onnl!I and handling equiprm;nt ... ut.:h <b pal l1.:1 trucks and \\Orkcr staiions. control panel-. and so on.

., l· nsurc that lloor -.hould al\\ays be <lry. non-slippery and clean ~. Prm itk curbing and channels lo accommodate 'alvc glun<l h:ul-.s anti m ·crllm\ '·

conJc.:n,~tles and drainage anti lead them lo Jcsig.nall!d holding and or cqualr ... at1on tml...o,; l(lr 1rcatmcn1 am.I f or rc:cm c~

-L No rinse-\\ atl·r 1ir Jrag-ouls shoulJ ... pill on the nom the most important item tnl~tll) igm1rc<l in smJll .1mJ 1in) unil'i .icross the cuuntr~

5. \holding pil ~hould he pn)\ 1dc<l to arrest accidental spills or lcal-.ag.1.:\ on shop llrnlr. slope<l ltm ::ircJs 11

6. 1·1oor -;hould he kept clean and free or obstacle:.. I'm unhindered movcmcn! or pcr•m n nc I

7. \\'hik filling or topping up tanl\s/ h~nh-. . <.:arc ... 1wuld he tal-.1.:n to prevent merllm\l\u-.1.. follo\\ing lc<..hnrqucs. • I it hoses \\ ith ..,pring loaJcJ no11h;., • l \ c.: metering pump-. ltl a1.:curatd) lran ... ll-r rcquircJ qualllitics. \\here ka. ... ihk • \\here \\Utcr i-; aJ<lcJ Jircdl~ rrom prpinµ. use.: llo..il li:-..d control' • Install bacldlt)\\- pre,entcrs. \\here \\all.:r 1s <lbchargcd helm' ..,oJution surface

68

. 0 c (/)

·5 c: Q) .0 0 0.. (.)

~ .._ en () a.. (.) -(l) ~ --c: <l) ()

en > z w

• SUJ)l'r'i'c regular!) nnJ l...ccp rccorJ .... ofull '11ch l'fWr:tlions. imlka1111g n\crlll'""· :ind 10 .. ~1!'\, spi Its CIC. \\ latt:h.T OCl'.Ur .... .

8. Rcgul.1rl) !.'.heck all alarm..... control de\ kl''i and 1111.•tcr!'.\/f"l:l'.,,rJl•rs a' per manul:1cturl!r· ~ .1dvicc

lJ. Chcd. all mewl protection -;uch a ... tan!.. lming. pa111ti11g on r:11lmg ... pip111g.. dia11i.... and h,mts and ckctricaltriping r.11.:k:- ag:iin:-1 $igm. ut corro ... inn. ,\ timd) inll'rH:ntion 'i:l\C:- ll•t t1f c\pcn:-hc repair: .... ~lmtdm\tb and moid:ihlc acdd1.:ni...

Rcjcl'l' and Waslc' ;;cncmt1.:<l in Elcctnlplating wa:-.lcs includ1..• the l'rilhm ing: • Prriccs:- \\':Hers of' ariou-. l.:inJs • Spent procc'" 'lllution' and ch:drt1l) 11 .. ·, • ~urplu.., d11..·micab • I mpt) cuntain1.:r:-.. packing mall.:nal' • ~craps of \'ariou.., kimb • SJuclgc~ .md tilter cake..,

Pro cs' \\'ah .. ! ~;i1.:ut J>rocc' ~' Ilion:-. ~11J ''!ffllu~ Chemic<ils

I he <.k · • "k1.:i con,idcrn1ions for th1.:· liN thn .. -c ha' c hccn J1~cui;scd in ( 'h.apll'r 4 al' J "ub'cl't inn' S. I through SA . I hmcvcr. general guiddtnc' cnn he summan'l'U :1' umkt .

I. \:. prcK·cs :-. \\a<;te\\atcr should oc :-.cgregal~-..1 .u:cording to their char:1c1cn ... tk' , \\'hcrt'\l'I fc~l' .. ihlc. rec0\cr: ~ '1 metal\; and other d1cmic:tl' 'ihould he re.:1ncrt:d

c:uc hcing taken h'l cn~urc unJe,ir.1hle ,,111 contcnl do 1101 1i,1.:· in l'Cl')dcd

.. , solution' Fie!\\ cquali ... ation tanks mu't bl: pro\'iJcJ hclilrc 1rca1111c111 nf' m'ious streams and in each 11ni1 \1pcralio1h

·I. l"or H.'1") 'mall \\ .1-.le\\atcr flu''· it i~ add .... ;,1hlc 10 haul \\:t'StC\\:th:r 111 a comlllllll trcaum:nt focilrl}

5 . I anks. p1p111g. \.alvcs. tilter\ shall he nl' c111T11.;11111 r1.:,ista111 rna1erials and kakproot \rrangcml!nl should he rim 1dcd 10 .irrc ... 1 k.11\agc ... h) channcb and curbings and hrollt!.hl LO ho lding l•1nl\ .,rcqu.d"a11011 1:m\,.s for l'urthcr tn.:.1tmc 111 tf Ji sposal

(, \u1 plll'i chemicals not meant for U\c 01 n:1t1m to \cmlnt. should be diluted and di-..dmrgcd sin\\ I) imo appropriate ... 1rc:tlll or \\,1,IC\\:llL'I': lhL') ... hould not h~·

dbposCd orb) disc:trJing them into gelll.'l'al \\:.l'ilL' hin-. 01' II 11\hfltg tftu11 c/11\1 /1 the

dra111 un lc'' spcci lie a lb._psrm i llcd h) n.:g11lato11 aulho1 i l il·s 7. I l:u,1rdoll'• chcmic<il' and \\a,le' 'hall Ix· di,p1hcd 1l1111ugh li~l.'ll"'l.'d c<1n1111:1l1r

-· c:

.u c en > c: (J) .0 {) a. u

OJ (_) a.. (_)

~

(J) ~ ..._. c (!.)

(..)

en -> z w

Fm.rt~ Comamcr .... Pacl-.ing \1atcriab etc.

1.,,mcc many chcnm:af.. u::;cd in elcLtn,plating •m: h'\ic. there b good chance that vinuall) ~in~ thing coming in contact \\ ith operations can he contaminated Good hou;;;ekccping "ill cn-.un: that this "ill not be the case and if contamination occurs. the~ should be dcwntuminated or disposed proper!~ The following may be noted:

I . TClols and equipmcnL.; ~hould he kept onl~ in dc..,ignatcd area and not lcn cl-.c\\hcrc

2 '-,cparntc \\aste bins for dift\!renl kinds of ,,a..,tc shoulJ he useu \\ith clear labelling and \\Orl-.er:, tr.:iined to use them 11 empt) contruncr; arc used as \\NJ'-lC hins. it ... hould he lir•;t thorough!) deaned and all pre\ ious markings phlik:1atcd and /or painted O\cr

4. t ontainers of to:\ic and ha1ardous chemicals should not he used l(1r other storage~ the} should he disposed as per manufacturer·-. instructions

5. 1\ll maicpals that arc cont.:tn11n.1lcd "i1h chcmkals can be cunsi<lcrcc.J to tn: to~ic as salet~ measure and tn.:atcJ according!) .

\ludgcs .am!_ filter Cakes

Disposal ut' .-.ludgc~ is no\\ one of the majur Cll\ ironmcnlal concern.-. l(n the dcctrnpla1ink industr:. Becau:.c of heavy metal content. sludges from \\~lC\\aler trcaunent plams arc considered hazardous. Many countries including India ha\C 1 cgulatimb concerning handling. storage and d ispl"al of such hazardous matcriab.

Based on the limlmgs of Lhe in-depth ~tudy. it \\as noted that in man) areas im:spct.:11\c nf 1hc '\tJtc centralised sludge di<;posal facilU) ha' not hccn huih h) the ~late Pollution Control Boards. In ~uch cases. the im.luslr) has been asl..cd to organise safe storage fo1 a srcLiffod period The following guidelines ma) he uscl'ul 111 thb regard.

"iludgcs should be compressed and dcwatercd Lo reduce volume as much a'i practicable

., They then should be poured in PF hags. scaled ant.I lahelled or tagged with date. quantity and description or con tent

J These bags should be kepi in a \\UU:rtil!hl comparllm;nt. prclcrabl) com.:rctc chunbcrs "ith lockable cover-;

·l Manual handling an<l or carrying a~ hi:m.JloaJ O) manual lubour should he strn:tly prohihiLed

5. f\1ost units simpl) sl<lfe them on roof tops or in "godo\\ns .. \\ith leak~ tin roofs, such practice allO\\S suflic11:nt \\Clltng and C'-'Cnlual run-off of such sludges entering soil and ground\\atcr, fh1s practice 1s against the spmt of cnvironmcnlaJ protection.

6. Formation of leachate must be a\ l1idc<l al all limes to prc\ent rcmobifo.ation or lo:xic and hazardou-.. suho:;tanccs in the sludge.

7. Pre-treatment and chcmicul !'>tahilis~ttion of the sludge h) the generator himself ma) be done. panicularl) by large units.

8. Only proper!~ de:,igncJ. corhlructcd and ccniliedfaurhon7ed landlill sites should be used for linal disposal.

71)

en () 0. () -Q) ~ ...... c Q) ()

(/')

> z w

Chapter 6

Rcvicn of Existing Sta nda rd\

6. 1 Genera l

Currcntl) th~n..' C\ISh an im.lustl} specific standard for discharge or d"llucm from clcc1roplating 1m.lu'itr) . ·1 his standard \\as promulgated under the En\'ironmcnt (Protcctilm) Ruic-.. 1986 and meant to be ob~cncd b) all L'lcctrnplating units as a

mini11111111 e1CCc!/Ut1h!e quulity of c!//l11t•111. The stale pollution 1..nntrol hnards or lhc k•1..JI n:gulatllf) authorit) arc cmpO\\Cred to form strider or more .. 1ringc111 rcl1u1rcmcnt-. dl·rem.ling on the requirement or the recipient cm ironment. 1 io\\evcr. 111 actual pract11.:c. 1110:-.t ll r the ~ P( lh fo I IO\\ these standards, \\ h lie gmnt 1 ng wnsenl fo1 d I sdmrgc 0 r effluent

l'hcn: 1s no indu!M)-spccifo: standard for air cm1s'i1011 li.1r ckc1111plating indu:-.tf) During the 111-dcpth stud)'. It \\as observed that for large am.I medium 1inits, there 1..ould be signilicant cm1ssion of acid mist from bath (pre-treatment and platin~ ). particuh1rl) from hot bath'> While. man) units voluntarily prO\ idc 'apour collect1011 anJ 1rcatmcnt through sauhhl:r not t:\cr} one docs so. This is more a mailer of m-plam ur 4ual 11) than discha1gc tu ambient air. Measurement.;; rc\cal that ctmcentrauons arc 11u1 high enough to cau-.. c alarm. hut monitoring over a sufficient I) long period can onl) J'f\l\ 1tk a morl! complete picture As far as rl!gulatof") standard for acid mist 1s concc1 1cd. J....arnataka \tatt: Polluuon Control Board (KSPCB) stipulatt:s a post-scrubber 1111111 11f '50 mg.'.m and a minimum Staci, height or 9 m above highest noor lc'vcl or ) m ah1l\ \! ground le\CI. \\h1c.:hcvcr is h1ghl!r ~laharashtra SPCB stipulates a limit of '5 mg1Nm 1 ~O~ and "10, corn.:cntrations even inside the plant and near \\Orker pos1uons are \\.ell \\llhm limits of amhient air qualll)

lh.~ dcctroplating operations do not include an) significant noise generating act1vil}. rhc main source of noise is air blower. \\ hich is used for prc-clean111g and 111 Baths like Nickel for gentle air agitation. During the in-depth stud). it \\as found that other mechanical operations in on integrated plant give rise to signilil:unt noise" 1thm the plant. In no case. high ambient noise \vas obsen ed outside the plant.

6.2 Sugges ted Revis ions in Existing S tandards. 6.2. 1 ~cctl for Revi~ion & Present Scena rio

In vit:\\ of the forcgoing. it is dear that re\ isions arc requircd in the e\lstmg standard ... to make 11 more appropriate to the state of the industry in the counlr~ and also to act a' a dn' mg lorcc for protection to the recipient en' 1ronmcnt \l the same lime 11 '" to llc home 111 mind that maJOnl) of units an: 111 tin) anJ smull '>l;Jlc. "ho :m: nut 1m111cd1atcl~ able 10 upgrade thc tcchnolog) to achie\c ck.mer produc11011 I lm\C\Cr. II is not possible to protect lhc ell\ 1rnnment in a significant manner. unles' cleaner production is achicvl..'d . Con!>cquentl). there is a need to adopt a balanccJ anJ practkal approach so that goal is achieved over a period of time

71

..--.. c (.)

c Cf)

> c CJ)

..c (.) 0... (.)

co u 0.. u

~

(I) i... ..... c Q)

u Cf)

> z w

lkhm: making suggc,tion' I n:i:,1mmcndation .... the fol Im' ing facts and constrninb a1 i: to ht: kept in view:

.,

" ' ·

4.

l·nll'•'\ion ~wndanh \\ilh respet:l to Industrial acth itic-. in general and Elcl:lruplating i11 particular arc hJ ... cJ primaril) 1111 health consitkratinns \\orkJ" iJ1: " 11..:h con ... i<lermion., rclah: to hcJlth ellccb nf pollutants 'uch as metals. to\tl 11rg.1111l' c·1111pou11Js and J\. ltJ~ Jl"Jhc.... l: ffcct' 1111 \\lll ken. ( i.\.·.. cxrw:.urc tu 1mhic111 t.:ll\ ironmcnt) a' '"ell a-. lhe rccipil-111 en\ ironmi:nt an: tal-cn into considerati1111 "hk lttrmululing ..,lamhmh. 1\-. more l\111m kJg.c through n.: ... car1.:h h1.:~:omc a\ .1ilahh.: more pollutant-. arc iJcntilicd and hroughl unckr rcg.ulatnr) stand•.mh and !->Landnrds an.: made more '>lnngcnl .

I he llll'.•llls of i.1l.hic\.111g sland•mh an: ch1l'.ll) baseJ on ''•Isle m1111m1sal1on. and re-.tril:tinµ ll'>C of hatarUOllS anU lO\iC ll1Utcnal' Und prOCC\SCS. J .'\Ulllph.::' im:lude (:t)

... trict limits lHl ( adm1um u ... c. (h) development and ,1sc of 11011-1.:yani<lc procc .. st.!' (c) uw nl Chromium (Ill) 111 lhc place ul (. r(\ I) and stricter control of use nf tu:\il-11rga11u. deaning sol\ 1.:nts ari: some nl the c:-.:1mpks I mprowmcnt on cJpturc and tn:allllCllt of ga'-COUS 1.!llllS'>IUllS. arc n.:~ultS of ri:gulat00 controls and Cll\ ironmcntal a\\arcncss. not the olh.:r \\a) n1w1i.I. Cost cf"fcdi\cness of treatment procc..,scs arc rc'u t-. 11 111Justnal competiti\cnc.;' to meet ell\: runmcntal g<1al-. for cornmnn good for the puhlic at large In India. the medium and large units. particular!) ··primary users"". caIT) out dectroplating <1" om: tif th.: npcrntions in a d1ain of inJu ... trial pwduction. l'hi:~ arc ahk Lo compl) \\ith t''\ist111g ... t .. mdards ;111d they ha\c Lhc ability and 1m:a1b to further 11nprnvc the orcralmn. thercb~ rctludng \\ash.:s hoth qualitati\ d) amt lJUamitall\d). t\lso. more reliable n.:curds. of material use. quantum 111" electroplating and \\aslc management arc a\'ntlahlc. which arc useful in achtt.:\ ing lnad-hascd c;Landard in future. l'his. fact '' al<>o rclkctcd 111 the L ' lcJer.11 n:gulntions. \\ h1ch al lo" such ··1n1cgrmcd l.1t.:il111cs to auopt load based ->Land;.irt.I. 1 c . rollutants rer sq. m. ol plated surlacc area In tin) and small scale opcrn11on'>. doing main!) job-\\Or"-. it is ncarl) impt,..,..,ihh: to h<nc Jn) rcltabh.: rccor<l of ·are:.1 nl' plated -.urfacc·. Introduction ur loud has.cd standard docs not appear tu he fcas1hlc for this sector.

·1 he small and tiny unit'i carry out holh job-\\ork and nlso \\Ork of dedicated customers (manufacturing .mJ.or plating of Original Fquipmcnt OF) \\hilc 'om\. ol" them do hoth. others do only 011C of them. /\l..,cl the~ lend lo S\\ itch het\\CCn the t\\o. <lepcndmg on the marl.ct for\.t.:'-

5. t'vlany or lhc-.e units do a 1111\ or plating or common as \\ell as precious mctab. 1"1crcforc. 101 thc ... e unib. 11 '" diflicult to dn:...,·r) them as ··common metals" category or ··prt!cious metals·· category. as u ... cJ in l \ h:deral regulation. Thal kind \•I <li\tinclton docs not appear to be feasible in India. at lca.c;t in the foresccahlc future

6. lhc most common problem ohscr.cd during in-<lcpth stud) is the highly disorganised pracl1cc of rinsmg and wa,.hing by tin) and small-scale units all across

t) ·-c: en > c: Q) ..c <.,) a.. u

co () 0... 0

-~ ..._, c: CD ()

Cf)

> z UJ

the country. I h1:rc 1., 'uh .. tantial :.co~ for 1mprmcmcnt in pt,llutmn control h~ '"') 111' \\:t,ll' minimi ... a1i1111. metal um.I chemical rccmcry

7 l·urthcnnorc. these 'mall and tin~ uni1' m.·uhcr hn'c the capacn~ h:chnical. linanl·i:il anJ managerial to adopt rull-scalc "a.;ti.:\\<th:r 1rcatmc111 technology. It i-. more ~•rprupri:uc for them to collect their \\aslc\\:llcr anti 1rc;11 in a < ·1 rl'. Where imlt1,1ri.1I c,t,1tc' arc not in cxbtencc M dinicult to .,1.·1-up. 1111, \\e111ld he ~1

prnctkahk ;md hcttcr managed option h~ u'ing t:t11h•r.;

8. Plating on plastic ~md t\luminium h~ts gairn:d popularil) :1ml man~ units <.lo 1111 ... t~ pc of plating. 1\ll) revision II! "lane.Jard 'hould includl.' Slh.:h 111Clallic pollut:.tllh like 1\lumini11m.

9. Dc ... ritc introduction ur mor~ cn\.inmmcnt-fricn<ll) p!\lC\.'\\C"' like ('\illlidL Free /111L Plating. Cyanic.le hascc.1 /inc plating " 'till h~ing 11'.cu \ulfo:1cnl .l1sL·11ur&1gl·ntcnl seem' to he ncce,sar~ agai1hl U'\l' ol ' such pron·"c'. C\t:lllll.ill~ h~11111ing ~ud1 rroccs ... c:-..

IO. i\ kt:tl rl.'CO\ cr) and Chemical rcco\ cry h) i1111 c~1. h llL'l'. l1.'l'h11iqucs ma) cause huild up of .,ulphmc nnd sulphih: ilm' in the \\a..,tC\\aH: "' 11.·c such rccove~ uugl11 tu he encouraged. thcrcb~ kading h.l a distinct und wn-.cquclll r<1,sihilit) of rai,cd concl·ntmtion of such ion:-. n : h: \\a'-IC\\atcr. The existing :standard doc' not include such r~munclcr:;.

11 . As far n' control of air pollution at source i' conccrmxl. the nll~ium and lnrgc unib. particularly "primal") users ... pnwidl'. J collection ')'st~·m t'I 'npour:-. am.I ga-.c~. follo\\c<l b) \\Ct scruhhing: Units in f....1rnataku arc ~1hk to compl~ '' ith c,i,ting standard!\ and they ha\C the ahilil) al'1'. ITIC<tllS to forthcr impr<WC the npcmtion.

12. The tcchnolog) required tu cnmpl~ "ith better and imprm cJ standards arc not onl~ available hut :tlso :iffordahlc to most mdu ... trial unit!'. The umkrl) ing principle i:-. lo \lrga111sc snwll scak and l111) units. i111rnJucc lllllH\.1-.tc method nl' \\tirking anJ 11ca11ng their \\astc colll:Lll\cl~ \\ hcre 1111r11Ju1.1io11 ul llll'.lal n.:cti\l:ry anJ rdatctl \\ask mini1ni-..i11n11 arc primar~ considcr;,11io11 .... lhl· technologies and pmcl·s,cs .ire adcquml·h a\;.11 lable and they arc CO'il dh:cll\l' too. 1 lw:o-l' asp1.·c1' ha'c hcc11 ampl~ md dahu1.t1cl) Cll\l.:rl.'d Ill Chapter-..., 1.111J 1< I he lksl ·\q1il.1hk I cchni4uc' (-.cc

'-tcltiun 8.4) do 1101 n.:t1uln: e\ce,sivc cost. In fact. they arc quite .1lli1rJahlc to holh :-.m.111 and medium operations.

6.2.2 Rccommcnc.lation for Re\ i ~ion in F\.~ting "ihrnc.l.ard

Hnscd on the line.lings or the stud). follO\\lng recommendation" an: made 10 rt:\ j,c the existing \\a,tc\\alcr di~hargc ~tandard :

1. Load hascd or concentration based? In case of mcllium and large unib. particularl~ .. rrimm~ users ... more reliable records of mutcrial use. q11an1um 111' electroplating and wa:-.tc management are a\j' lahle. \\hkh urc useful in :1chic' inQ load-ba ... cd 'lam.lards in futurl'. This fal:l 1s J!so rdkclcd in the lJS lcderal 1cgulati11n'. \\hich

73

,.._, c.:: ()

c.:: (/)

> c: Q)

..0 u Q. u

co () a.. () -Q)

'~

c Q) ()

Cf)

> z w

allu\\ such .. mtcgratcd faci lit ks to adopt lom.1 bas1.:d sta11Jards. 1.e .. po l I uwnts. m ~. or plated surface area In Lin) and small scah.: operations. dl1ing maml) job-,.,.ur!... it is 11c3rly impossible to have an) reliable recnr<l or ·plated ... urlacc area·. Introduction of loa<l lx1-;cd stan<lards docs not appear lo hi.: fi::.isihh.: for this ... cctor. Therefore. ll 1s

nol a~h isahlc lo introduct." loaJ hascd \tanJ,mh. II . Point ur discharge'' ~lllCl' eh.:ctruplating \\:.ISlC\\<ilCI contains highly lU.\ic

constituents and cons1dc:nng enough ,,,,pc for undcli:cted <li...chargc with high h.:\\:f:.. of pollutants. il is proposed to rt."SlrtCt d i-,clur~L hl pub I ic SC\\Crs nnl). l°hl: standards arc to be commensuratc with dilution a\ ailahk hut to \\ ithstand ad\Cr'le t."ffcct on biota rc-.ponsihlc for biological treatment uf \\~t-.IC\\alcr in '>e\\ 1.:_!C

treatment plan1s. 111 . Difl\!n!ntiation bcl\\ccn common metal' & j)rcdous mdals'! ~Ian) 1\f electroplating

units C<llT) out a ml\ of plating of co:nmon a~ \\ell a~ precious mctab. I hercforc. for thc!".lc units it 1s dillicuh to classify them .1~ ··comnmn metals .. catt:gOf') or .. pri:cious mctab"" CJlegOf'). ~ used in l \ lcdcrJI regulation. That kind or distinction d<'k!~ not appear to be l\!a,1bk in lnd1.-. at least in the forcsecahlc future.

''. Dilfon:ntiatton bem:cen small and larnc \\astt'\\atcr prnducunn'? t\11 acros~ the CNllltf'). a clear and common picture of dismal ~ituation in .\aslc\\atcr management 1s observed in the study Despite e'\istern:c of ~tandards t(1r the last sc\'cral )Ca.rs. these units ha\ c continued to operatc '' ith impunit). violating dischargt> standards. C\ en "ith consent orders. fhe smJll anti tiny unh'> Jo not ha,·e the technica1•

linam;ial :111J managerial capacities to adopt l'ull-'>calc \'-astc ''atcr tn:atmt:lll tcchnologie .... It is more appropriate for such units tn 1.:nlkct their \\"listC\\ater and treat in a CETP. rhcse units. dischJrging upto I 0.000 kilolitre/annum or corresponding!) 33 kilolitre dail~ must c'crci'ic an option of cith1.:r (a) maintaining and operating their O\\n \\3SlC\\Jtcr treatment plants indi\'iduall~ or (b) transporting their , ... USlC\\<llCr lo a c 1:- ·1 p through lank.er-.. I his stipulation Illa) be \\aivcd in cases \\ hcrl.! action 1s al read) un<lcr \\ J) lo :-.hi Ii and regroup such uni ls in an nrgan11ed industrial cstmc in a nc\\ loc<1tion. !"his must be the rcsponsibil1t) ur "itatc Pol lution Comrol Bodrds

Large and medium unit s m::iy ei ther co11l1m1c to opl!ntlc their own wastc\vatcr lrcauncnt facili ties (but \\ ith more cffecli\c monitoring) or voluntarily to opt for transporting lhci r wastewater to cr:·1 p through tanh.l.!rs

v. lm: lusinn of additional parameters?

Judging h) the present trends in ckctropla1111g and considering slandards bt!ing Jdupte<l in other countries. 11 is evident that the cxisling list of parameters (refer Anncxurc-11) needs to be expanded.

Plating on plastic and Aluminium has gained popularity and many units do this l) pe of plating. An) re\ 1s1on in stantlards shllUld include such mdallic pollutants like Aluminium.

74

-c ci ·-c (,/)

> c Q) ..c <.,) Q.. u

ca u 0... u -~ ..... c Q)

0 Cf)

> z w

\ ' I ,

\ II.

Metal n.:c1WCT") an<l chemical rccll\ery h) ion l':\Ch•tn~l. tL·chni4ucs ma) l'~tthC huild up of sulplli.1tC am.I -;ulrhitc i1lll' in the \\astl'\\ater 1.\1111.'c srn:h n.:cn\cr~ ought tn bl.' cnc.:nurageJ. thcrch~ leading to a d1stmct and t;or1'cqw:nt po,,ibil11~ of r.ii,cd l'llllCCnlration or :-uch ion-. in the \\aSIC\\atcr. I he C.\i,1i1lg ... tanJarJ Jue~ 11111 include -.uch parmnch:r...

I hc additional par•urn:&cr' along'' ith their limit value' arc p111pu-.cd in Tuhk-CLI

~I. '\o . ._ Paranu·tcf"' Limit ,·~luc (mg/I) l ' I u he impluncnh:d inu

t

I Aluminium

1

5.0 Pl1.1''" I 1 t Tin 2.0 Plm.'c I 3 Silver _ ~ 1.2 Pha~I..' I 4 J l~luori<lc:- (a-. I'· .,.. 15.0 Ph!be I

t _ 5 c.;ulphidc~_! .i..' "1 ,_ ~.o Ph:N~ I 1- h '-l_!!plm1cs(a~'-1=__ -WOO l'ha~c2

7 I rid1lt'rPclhanl 1 0.5 Pll!N: '1 L 8 I Trichlt1rncth\ lcne r 0.5 .l Pha'\e 2 9 ~ Phosphate' c ~ ... i.1._ --[ 5.0 Pha">c 2 _

'\otc: ..- f hi" p~mll11Ctcr ma~ he intn1Jm:cJ in f'ha~t.'-1. 1)10\ 1Jc<l thl• lm·al Ullll

.11 the \talc Pnllutinn (. unlrol B1larJ 11.:d-. that a highl..'r \<tlul' is likd~ lo

disrupt tht. <ipcratinn nl ln1..JI sl!\\age u~·1tllll'lll 1'1~1111 and aJ,o cau-,1: -,ulph1ck cmrosiun in ..,l!\\er~ . "* It is pwposcJ th.it the r1..·\ i:-.il1n he implt.:llll'lltcd in t\\11 pha-.c . Implementation or Ph .. 1-.e-l .. hould llllllllll:IKl' tin lht" <l:tll' cir no111kattllll 11 -.1.indanh and for the imrlc1111..:111a1ion of Plw-.c-2. a 2 )Car time rcmld 111,1,

b1.· .1110\\cd for the 111dus1r~ to org,tn1'>c 1hcmschcs.

I m ironmcntal Jricndh pro1.:c~scs'? lksp nc tnlroduc\ion n l morl' cnv1rnn1rn:n1-lncndl~ pruCCS'\C\ lil-.c ( yaniJc rrcc /.inc Plating. c~.111id .. hasc<l /111L rl•tllll):! ,, still hc1ng us1:d "iurti1.1crll d1-.1.t1uragcmcn1 '1:cm-. tn bl' ncc.:cssar~ .1gatns1 use ol surh procc-.scs. e' cntuall~ harming -.uch proccs">cs.

\1J~lution! \t present thl'rC I" 110 rcgulalOI') SltllldJrd.., for ai~ hMlll' pnllutanl-. sr ~·· ilic tu the ckdruplat111g 111duslr~.

1\t least. large and ml'dium dedrc'plating unit!'> arl' required h1 p111\ iJc t'ff<.'c:tin·

ct1lkction ")~lcm ot'ga,c-. and ,,,pour~ from all hot hath' <111d tn:at thc ga-.1..'' an<l \'apour.; ,., ith ~• \\alcr -.cruhhcr in !irc"t phase. 1 lu.: 'cruhhcJ g<is"·s ,houlo ctmfurm t·1 the ~tandarJ~ ,1-. prnpnsl!J in Tahlc-ll.2 . Ph:t-.l'J implcmcnt~Hitm j, suggc..,tcd. considering prcsl'nt !-.late of the indu$tr~ and facditic~ l(H rdi:.ihk 1es1ing an<l nnalres.

75

.......... c (.) ·-c Cl> > c: (!.)

..0 u 0.. (.)

ca () CL () -~ ...... c Q)

0 (j)

> z w

\ 111.

~. '\u.

.,

-4

l'aramcrcr

\1. . d \ li't (I ICI & ' I_"(_ I . )

• ;;.uJ

1:1111"ion I imil lll l! '\m

1 To he

implemented in Pha~c-1

Ph:i ... c-1 ~

Nickd 5 Pha-.t:-2 Chromium (\'I) 5 Pha:-.c-2

.. Chromium (Other ) f 5 Pha .... e-2 --t -- -- ----- • --

(1 • ! 5 l Pha'lc-2 ~t1tc: 1.:-.i ting ... 1andanh for Sc)~ and i\C l, ~hall 1.•t111tinue to hi: applicahk.

\l111111urin!!'! I >uc ll t '11 .... c~ 11a1un: of the \\aste\\ah:r ol' clectropfati'1~ imJu-.t~. it 1 t•nt prnctical to dti ·h1. lllllnitming c1uik· lh.0\Jlll.'nll). Sa). C\Cf) \\cc"- ·1 hi .... ~\\oulJ I\\: 1.1thcr 1.'\Jl\.'n'i"-· and 1c~, lil-;d) to he follo\\1.-d in pr:1cticc. On "11. titha hand. i( montlnnng '' d011i: at llingcr intcn.ib. '·') once n month or 0111.:c C\Cr) t\\ll month .... tlu..· rl.'.tl p11.' lllf1." .1hout ..'.l111lplianc(' \\tHlkl not 111.· 3\ailt1hlc. lcadmg to ddcat or the 'c1) purpl1'\c of monuorin~. I knee .1 middle path :-ccm~ to he n.:.i~onahk prm:lical .mJ impk1111.·nt~1hk.

• ~nmc sckctl" I r<Jr'.ll' eh:rs (l'admium. l hmnuum jl'r (\'I) and Cr (I otal)I. l ):tlltdl!::.. t 'oppcr. ~ hl'r and ~1d.l'IJ h~ muniwrcd 111011: fr1.·l.llll!11t l). \\hile otha p:11a111cti:1., he momtnrcd at ln11gl'I' i1llcrv<d,.

• I 11 l.".tsc 1)f till) and small unib. the 'elected pa1:.i111ctc1 s neeJ hl he monitored :it lca-.1 1111i:1.· :.1 \\Cl.!k. g.encratin!-! '\() to 5:' , 1-. nf \;dllc'i 111 '..l )car I he other jl:lntlllelt:rs lh.'c<l to he lllOllitored al lc.i-.t 011\.C .l llllllllh. gi:m:rallng 12 'els or \al111.·, in <I year. II l)5u,., compl1•111c1.: i-. cn-.mcd lht.: pt.:rformancc lll:.l) he t:nnsidere<l !'-.1l1!--la<.:ton

• 111 1.":t'>I.' ol 1m:dium anJ l.irgc 1111i1:-i. the :-.dl·ctcd par~11111.'lcrs nccd to he..: moniton:<l d.lil) and the 111hcr paramctcr:- 11cl·d In hi.' 1111111i111rc..·d 1111c1.: a l(1rtnight

• \\ hcrn i:-r 1t is possihk. 1111\\ ha-.cd gr:1h ':11npli11g b 111 bi: <lonc 1<1 get rl.'pre-.ent:nh c '~tmpk.

• '1 u1rcc pol l11t inn for air e1111.....,11111 (...,,ad, 111011it111 ing) shnulJ be: carried out month!~ under normal llpcr::iting l'<111Jitio11'

The: proposcJ standards are gh en in ·rahk b.J

76

c (.,)

c en > c Q.)

..0 (.) 0. , ' \..I

~

~ -co u n.. u -Q.) I.... ....... c Q.) ()

en -> z w

1':1hlc 6.3 Propo,l'tl \\ a'tt\\ a1c1· l)j.,drnr~l· i...1;uul:•ru-. for Ekl' lroplati11g

lnclusl~

-c (.)

c . (}) ·-> c Q) ..c (.) 0.. (.)

CXl () 0... ()

~

Q) "...... c (1)

(.)

(/)

> z w

CunCl'lllration not to c\cccd To hl· SI. Parameter., ( mJ!ll, c\n·pt fl II & implemcnlcll ;\II I l'IH Pl'J';t f u f'l' I in**

(1.0 to 9 0 "t

pl I ....... ;· 1.: I ,i,ting

., I l•m perm ure '\hr.II 1101 CXCc\.·d : l' ahm (' thl' ..... l" I '''1111g -.11nhicn1 1l'lllpc1Jllm.· orthi:

rl'l'l'I' mg hod)

..--.. -~ ; ( >11 & l Jn.'.bl' I 0 'mm: 1 '\lslln!.! ()

c .l ..... u .. pcndcd ~oli<l .... IOU ..... 11.! I "'ting (/)

"> .. ( )nnid"' (as CN) 0.2 ", ne I. ,j..,ung c: (L) ..c

J\nunonial"al ~i1rogen (a' l\ I 50 " 1·11.! 1 ·~1 ... 1in~ I (.) 6 0.. (.)

~ 7 1

I oral Rc.;u.Jual Chlorine (a' <'I) I I 0 " c l·'\i..tin•• eo

~ x ( .1d nu um (a' CJ) 2.0 " · l' I ,j,1111~ ._ en () l) !\1d.d {ar.. ' ii HI ..... 11.· I ........ 1111g I a_ 0 tu /ml (:t:. /n) 5.11 .... I 1.: I "'I lllt! -Q) ho

'°'~11111.: I ,j..,1i11k-....... 11 I k\11\,tk-111 l hrnmium (a'< 1, II I c Cl) () 12 I u1,d ( hromium (,i... C r) 2.0

1

C...,.1mc I _,j..,1i11g. (f)

> I~ [ (. opp1.:1 (as l L_1) ___ 1,() C...,411nc l ·. ~b1111~ z I -w

1.1 I cad'''" Ph) ll . I ..... 1 ll' I \is1111g

, .. lnm (.1s I l') 3 (I ..... 11.· I ""ling

I'' I <'I.ii \k1.1I Ill (I ~:11111: I ,i .. 1111~

l'h.1'c I 17 \ tum111iu111 .. ()

l'h.t'l" I IX I, .:' I)

Pha .. c I I IJ , ,l\c1 I.:?

r Pha~c I

'20 I· louridcs (nsl· J 15.11

I • Pha:-t: I

I

21 ~ulphidl·-. ca' S) 20 Pha,,·.:: ., ") "'ulphatl·' ( ~ )• I (I()

l,ha ... c 2 ,. -·' I m:hlnroctha11c ..

Pha:-.c 2 24 I nchlor1,cth~ knc 5

Pha''-"::: :!5 1,ho-.phatc (a' Pl ".0

(,,J lh-commcrulation for Monitoring of Rt-\ j,ul Stanclnnl

During thl· in-depth 'tudy. it ''a:- 11h:--er\'Cd that 11hmiloring of \\U-.ll..'\\<Jtcr 4ualit) fr,,111 clcc1toplnt111g units ''ere neither uniform tllir rq:ul:ir :ind \\ell ddincd. In nrdcr for th\." ~tonLIJrd-. 1t1 he meaningful!) utilbcd for prntcction ol l'll\ 11·011mc111. m11111toring -.hnulJ he cam1.:d l1lll al regular intcn al and a ckar ·~J, 1:111ding of compli:1111.:l'. requirement j,

ncn·":tr) IH hoth th1..• monitoring .1g1..·nc) ' 1 c P1>lhllhlll l omrol f\1,:111J,1 .111d till' mdu ... tr) .

I >u .. • to thl..' 'er) 1t.1lun: of the ''a'l'-'''ut1..·r of ck1,.·1ropl.11111µ inJu,11). 11 ,.., 111'1 prn.:1k:.il to Jc, th\." morntor111g. <!llllc frequent I).'·'~. C\ er) \H:d, I hi~ \\ould he rJtlk·r c'\pCt1'1\ c and le'' likd) 111 he liillcl\\cd in pr.ictk\." I In lhc otlh:r h:iml. ii' 11111111tnr111g •~ Jrn11.· al long,·r irllcl\ nt ....... :1~ 1111cc llHHllhl~ or once I..'\ Cr) l\\11 1111111th,, thl· re.ti pii.:tt11c :1houl l'llmpliani.:I..' \\llLtltl 11ut h1.• :l\ail::ihk. lcaJing t.i dcl\:-:it of tlw • 1.'I) purp"'c nl 1m111itnr111~ I lcn.:c a m iJdh.· path ,1..·c111 ... lo hc rca ... onahk. prm: 1 ical and i 111pk111c111:1hk

l 'on ... 1dcring the above. it ,.., suggested thal .01111.: '-l'kcl\.·J p:ir:11111.:tl.'1 h1.· 111onit11n.:J more l'1cqL1i.:111I~. \\htk other paran11.;tcr-. hc mornl1Hcd :11 l1111gc1 11llt:l'\:1' -.. Par:1111dcr" lil-.l' ( admil1111. Cl11 u1111um. I( r( \ I ) ~u 1d l r ( I )I. l ~.1n 1tk .... t uppu "'11\i.:r .ind '-li1..l-.d 1itxJ tu h.: mo11it11rcd 111/n' l'l't1:1 11'1.!t'k. I hat \\otlld pnn Ilk a d:lla 111 "I() to 5~ ... ci... l'\ 1.·r~ ~car Ir 1>'i 11

.. c<1mplia11c1,.· i' i.:1 1..,urcu. the pc1lo1111c.ull'c ,IJ,,llld h1..· t'1111 ... id1..·1l·d -.:11i ... 1.1unr~ Clthi.:1

('!llll111l'll'r... ... hould h1.: mw11tnrcJ u/ fro\l 1111u• 1111111111/1. ~l'llt'r.11111~ 12 '1,.'h 111 \,tlu1.·, ,,1..1~ ~l'.11'. 1 ,,, thc,1.• pa1:111h.:lcr' .11" '>5"o 1:11111pli:tlll.'.I.' 11111-.1 lw llll'I I hi' should h1,.• .1pplil'ahk In :ill tin) :111d small unit'. l or 11k·diL1111 .111d lar~1.· 111111,. d,11/\ 11111111111rt11l! 11r ,dcl."11..·d par .tllk'h.:1-. should hc i.::11T11.·d out. c >th,·r JMr.tllll"IL'I' l".111 hl.' 1111111i1111\·d tTcn /or/111'..!,/11

II '' H'f) imp11ri.1111 to ll\llc that l(ir ,•a .. :h unit. thi: '') k ul 1'u11i.:1io11111r :111J 11p.:rat11.111 111"

tn:at1m:111 1:1ciliti1.·, -.lw11ld he kmm 11 10 the 111011ttoring agcnc~. I tu ... 1:1c1t1r ... h11uld h.: · nigr.1111mc -.h1n1ld he \Hillen chmn and .1grl",·d

hcl\H."\'.'11 thl' m<lthlr) :mcJ the ~tgcm.· 1 \PClh) '' h1k gr:1111111g and 1•r 1\.'ll'-'" mg l..'<•t1'cnt 11rdl·r' \111111111nn~ -.hould follm' ,1.,..... ,1g1 ccd p1 ng1 :mune. I I' th"· 111du .... 1r: j, 11011-

l un\.'111.111.tl Jul' to co1nt11l·r .. :1al (lf art) othl'r rc.a...tm. 1h,· unit nu.-.t inl(irm thl' ag1.·nc: m Jul.." 111ne to .1l'l'om1110Ja11.· all\ d.:' i:uion. \\hid1 !llsn mu ... 1 h1.· n.·cnHll..'.d.

-.,

-. c 0 c: . t./')

"> c (],) .0 Q a.. u

en l) a.. l)

~

Q) 5-. +-' c Q) l)

(/)

> z w

"'' m:c Pollut1u11 lnr air l'mi ...... ion 1-;t:icl.. 111n11i1or111g) ,finuld h1.: l'arric<I <1u1 11111111'1~1 undl'r 1w1 mal opcra1111g conJition~ .

6A ~a ll' kccpinJ! of Da ra

Kl'l'p1111 .. : data m .: c.c.,•rd::. ,nfol~ .111d in .1nH.11111cr1ha1 <law can he rctril'\cd at t.'n"c '' lll great imporH111c.·c. '-u~h J:ua ftmn ,! rcliabk h.1 ... c 11'-c.'r \\hid1 lo huilcl and modil~ from timl' 111 11mc :i;~~l.:tnr~ or otha 'uitahlc mi:ch:mi,111 for pollution control :mJ cm m1111111:nt prntcction mca..;urc'. It j, rccnmmcn<.lcd 1hi.1t <l.11a shou Id he kept 111 cumputl·ri,cd data-t'ia..;c for .1 period nf at ka .... 1 5 ~cal' l>i1la ledger-. co-... ignl'd h~ mJu ... tnal unit and monitonng .1gc.'nl' ~ .... h,1uld he.· kqit . ,jmila1 lo uuditc.•d :1ccounh rl'co1d .

XII

... ---.. c.: (.)

c en ·5 c Q)

..0 (.) 0. (..)

~

~ ._ co 0 a.. 0 -Q) L.

+-I c Q) ()

Cf)

> z w

-•

--

.-. c ·-0 c (/')

-~

> c Q.) .0 <...) Q. , ... u

t ~ ~ ._.

co 0 a... 0

-ID ~ ~

c (!)

(.)

(j)

> z w

COMPREHENSIVE INDUSTRY c. DOCUMENT ON …cpcbenvis.nic.in/scanned reports/COMPREHENSIVE... ·...

Documents

Transcript of COMPREHENSIVE INDUSTRY c. DOCUMENT ON …cpcbenvis.nic.in/scanned reports/COMPREHENSIVE... ·...