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,ml~?--,--7~ T.-.-x-v.~

S i " ' 1E L S E V IE R Desalination 152 (2002) 315-324

D E S A L I N A T I O Niwww.elsevier.com/locate/desal

Adv a nc e d t r e a t me nt f o r munic ipa l wa s t e wa t e r r e us e inagr iculture. U V dis infec t ion: parasite rem ova l and by -pro du ct

f o r ma t io nL o r e n z o L i b er tP * , M i c h e l e N o t a r n i c o l a b, D o m e n i c o P e t r u z z e l l i b

Department of Civil and Environmental Engineering, Polytechnic University of Bari, viale del Turismo 8,74100 Taranto, ltalyTel. +39 (080) 5963-368; Fax +39 (080) 5963-282; email: l.liberti@poliba.itbTel. +39 (080) 5963-477; Fax +39 080 5963 635; emails: notarnicola@poliba.it, d.petruzzelli@poliba.itReceived 30 March 2002; accepted 12 April 2002

Ab s t r a c tThis paper reports the experimental results of a pilot-scale (100 mVh) investigation, carded out at the West Bari(S. Italy) municipal wastewater treatment plant, focused on parasite removal and disinfection by-product (DBP)formation during the UV disinfection of clarified (CL) and clarified-filtered (F) secondary municipal effluents atdoses necessary for achieving the Italian microbial limit for unrestricted reuse ofwastewater in agriculture (2 CFU/100ml of total coliforms). The investigation demonstrated that parasites like Giardia lamblia cysts andCryptosporidium parvum oocysts were both significantly affected by UV radiation and that potential UV-promotedformation of DBPs (nitro-phenols and N-nitroso-amines) did not occur according to GC/MS and LC/MS analyticalevidences. O&M costs ranged from ~ 17.5 up to E 35/1000 m 3 or effluent F and CL respectively.

Keywords: Cryptosporidium; Disinfection; Disinfection by-products; Giardia;Treatment costs; UV rays; Wastewaterreuse

*Corresponding author.Presented at the EuroMed 2002 conference on Desalination Strategies in South Mediterranean Countries:Cooperation between Mediterranean Countries of Europe and the Southern Rim of the Mediterranean.Sponsored by the European Desalination Society and Alexandria University Desalination Studies and TechnologyCenter, Sharm El Sheikh, Egypt, May 4-6, 2002.0011-9164/02/$- See front matter 2002 Elsevier Science B.V. All rights reservedPII: SOOl 1-9164(02)01079-2

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316 L . L i b e r t i e t a l. / D e s a l i n a t i o n 1 5 2 ( 2 0 0 2 ) 3 1 5 - 3 2 4

1 . I n t r o d u c t i o n

M unic ipa l was t ewa te r con ta ins a va r i e ty o fpa thogen ic o rgan i sms o f human o r ig in . D i seasescaused by these pa thogens can occu r a s a r e su l to f i nges t i on o f un t r ea t ed o r imprope r ly t r ea t edwater , inges t ion o f infec ted aquat ic food species ,sk in con tac t w i th con tamina t ed wa te r and wi thimprop erly disinfected was tewater eff luent in reuseappl icat ion . Such d iseases are more l ike ly in coun-t r ies charac ter i sed by scarce ra infa ll , l ack o f f resh-wa ter resources and high grou ndw ater salinity as inthe M edi ter ran ean bas in w here agr icul tura l reuseof munic ipal was tewater i s becom ing a com pulsorycho ice fo r wa te r r e sou rces manage -m en t .V a r i o u s s c h e m e s o f a d v a n c e d ( o r t e rt i a ry )t r e a t m e n t h a v e b e e n p r o p o s e d i n t h e l a s t t w odecades w i th t he so ca l l ed " fu ll T i tl e 22" scheme[1 ] , i .e . se con dary ef f luent fur ther subm it ted toclarif loccu lat ion, sand f i l t ration and f inal disinfec-t ion , most of ten adopted so far . The increas ingoccurren ce ofbio-resistant microorganisms and n ewpathog enic species , in par ticular , makes adv ancedd i s in fec t ion a key - s t ep fo r mun ic ipa l was t ewa te rreuse in agr icul ture [2].Actual ly , munic ipal was tewater ef f luents arecom mo nly d i s in fec t ed by ch lo r ina t ion . How ever ,p r o t o z o a l i k e Cryptosporidium parvum a n dGiardia lamblia and helminths l ike Nematodes,of par t icular concern caus ing le tha l d iseases ini m m u n o c o m p r o m i s e d p o pu la t io n s , h a v e d e m o n -strated to b e resistant to ch lorine-b ased disinfectionproced ures [3 ,4] . Fur therm ore , chlor ine i s kno wnto ra ise ser ious toxic ef fec ts on l iv ing organisms.In fac t , i t can reac t wi th organics conta ined inmun ic ipa l was t ewa te r t o fo rm va r ious t ox ic ch lo -r ina ted hyd rocarbons , such as t r iha lomethanes andre la ted d is infec t ion by-products (DB P) , know n asan ima l ca rc inogen and suspec t ed to be ca rc ino -gen ic t owards hu ma n be ing [5,6 ].

Accord ing ly , a tt empt s a r e unde r w ay wo r ld -w ide to ad dress the effectiveness o f safer alternativedis infec tants able to me et the s t r ingent microbia ls tandards usual ly requi red for was tewater rec la-

ma t ion and reuse in agr icul ture [7].In th is context , a 3-year R& D projec t par t ia l lysupport ed by the European Com mu ni ty wi th in t hef ramew ork of the Avicenne In iz ia tive was in i tia tedin 1996 on variou s technical and health care aspectso f advanced t r ea tmen t fo r w as t ewa te r r euse .

The I t a l ian i nves t iga t ion , ca rde d ou t by m eansof a 100 m3/h d is infec t ion p i lo t p lant pu rpose lydes igned, bui lt and opera ted a t W est Bai l (S . I ta ly)mu nicipal was tewa ter t reatmen t plant (3000 m 3/h),was spe c i f ica l l y a im ed a t com par ing pa thogenremova l , d i s in fec tion by -p roduc t fo rma t ion andcosts o f 3 al temative disinfectants, nam ely UV rays,peracet ic ac id and ozone. For each d is infec tant ,the influence ofwa stew ater quali ty w as investigatedby d is infec t ing 3 d i f ferent munic ipal e f f luents ,nam e ly seconda ry ( I I) , f o l l owing ac t iva ted s ludgeo x i d a t i o n a n d s e d i m e n t a t i o n , c l a r i f i e d ( C L ) ,fo l lowing a lso pos t -prec ip i ta t ion wi th a luminumpolychloride, clarified-filtered (F), furthe r subm ittedto sand f i l t rat ion.The g enera l resul ts of the inv es t iga t ion as wel la s t hose conce rn ing pe race t ic ac id and o zone d i s -in fec t ion have been a l r eady pub l i shed [8 -11 ] .Par t ia l resul t s of the U V inves t iga t ion refer r ingto bacter ia l inac t iva t ion ef fec t iveness have beendescr ibed in a prev ious note [12] .

This paper repor ts fur ther on U V dis infec t iono f clarified an d clarified-filtered m unic ipal effluents.The investigation w as ca rde d out at the disinfectingdoses necessary for ach ieving the I ta lian m icrobia ls t a n d a r d f o r u n r e s t r i c t e d a g r i c u l t u r e r e u s e(2 CFU /100ml o f t o ta l co l i fo rms , based on thewe l l kn own S tat e o f C a l ifo rn i a W as tewa te r Rec l a -mat ion C r i ter ia , 1978) wi th speci f ic objec t ives of : evaluating the effec t of UV dis infect ion towardsse lec ted paras i t ic pa thogens of ten occurr ingi n m u n i c i p a l w a s t e w a t e r (Nematodes e g g s ,Giardia lamblia c y s t s , Cryptosporidiumparvum oocys ts ) s e a r c h i n g f o r e v e n t u a l U V p r o m o t e d D B Pformat ion ( i .e . , n i t ro-phenols and N-ni t roso-

amines ) d r awing econom ic e s tima tes.

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L. Liberti et al. / Desalination 152 (2002) 315-324 31 72 . M a t e r ia l s a n d m e t h o d s

The inves t iga tion was car r ied out by mean s ofthe 100 m3 /h pilot plan t (Fig. 1) with appropriateconfigurat ion for comp aring he performance of U Vrad i at i on on 2 d i f f e ren t mu n i c i pa l w as t ew a t e re f f l u e n t s , n a m e l y c l a r i f i e d ( C L ) , d i s c h a r g e ddi rec t ly f rom W BM P and c lar i fi ed- f i lt e red (F) ,obta ined sub mi t t ing CL to pressure sand f i lt rat ion(MF) in the pilot plant. UV disinfection occurredin a non-contac t apparatus (UVA ), where in thew a t e r f l o w s i n s i d e T e f l o n tu b e s s u r r o u n d e dexternal ly by low pressure Hg vapor lamps .The com par i son w as pe r fo rmed a t U V dosesrequired for m eet in g the I talian microbial s tandard(2 CFU /100ml of total co l i forms) previously foundto be 100 and 160 mW s/cm 2 for feed F and CLrespectively. O n th e contrary, the ma x do se achiev-able in the condit ions investigated (430 m W s/cm2)was n ot enou gh to m eet the s tandard wi th feed I I,even i f the to ta l col i form value achieved (5 CFU /100 ml ) w as ve ry c l ose t o t he t a rge t. Fu r t he rdetails on pilo t plant, feed characteristics and m ainresult s of the previous part of the UV inves tiga tionmay be fou nd e l s ew here [12 ].

For both feeds F and CL , about th ir ty cycles( i.e . a g iven feed subm i t ted to a g iven dos e) wererepl ica ted in the same condi t ions in order to ch eckfo r s e l ec t ed pa t hogen i c pa r as i t e s ( N e m a t o d e seggs , G i a r d i a l a m b l i a cys t s and C r y p t o s p o r i d i u mp a r v u m oocys t s ) before and af ter d i s infec t ion aswell as for potent ial DBP formation ( i .e . , ni t ro-pheno ls and N-ni t roso-amines) .Analyt ica l procedures were according to Stan-dard M ethods [ 13] except as sp eci f ied below : G i a r d i a l a m b l i a cys t s and C r y p t o s p o r i d i u m

p a r v u m oocys ts : the me thod (Standard M ethodNo . 9711 B as m odif ied by Portincasa [14]) in-volv es pressure (4 atm ) tangential ulaa filtmtio nof a 10 -1 s ampl e t h rough 142 m m d i ame t e r(1.2 ktm porosity) cellulose acetate m em bra ne s.The m embranes we re eluted wilh 0.1% Tw een 80solution us ing mag net ic s t i rr ing and th e e lua tewa s centrifuged at 1 500 rpm usin g plastic tubes.The cent ra te was pur i f ied by P ercol l - sucrosegradient and ident i f ied by microscopy us ingimmunofluorescent monoclonal ant ibodies. N e m a t o d e s eggs : the meth od (not s tandardizedyet ) involves the f i l t ra t ion of a 2-1 sample ,

mem brane e l u ti on and cen t r if uga t ion a s f o rp2

~ 7

t,tl..- UV A

U V C P

V

Fig. 1. Pilo t plant configurationduring UV disinfectionexperiments MF, multilayerpressu re filter; RV, 5 m3 fibre-glassvessel; UVA ,non contactTeflonUV apparatus; UVCP,UV control panel; P, pumps; FM, flo w m eter; V, valve).

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318 L. Liberti et al. / Desalination 152 (2002) 315 -32 4G i a r d i a a n d C r y p t o s p o r i d i u m . T h e c e n t r a t ew a s i de n t i f i e d by pha s e - a n d d i f f e r e n ti a l - in t e r -f e r e n c e - c o n t r a s t o p t i c m i c ro s c o p y .

N i t ro -pheno l s : l i qu id - l iqu i d e x t r a c t i on G C / M Sm e t ho d ( S ta nda rd M e t hod N o . 6410 B ) m od i f ie df o r e x t r a c t i o n a n d c o n c e n t r a t io n p r o c e d u r e s :a 2 - 1 s a m p l e , p r e v i ous l y f i l t e r e d on 0 . 45 - m mc e l l u lo s e n i t r a te m e m b r a n e , w a s a c i d i fi e d a tpH 2 w i t h s u l phu r i c a c i d ( 1 :1 ) a nd e x t r a c t e db y v a c u u m f i l t r a t i o n o n a p r e v i o u s l y c o n -d i t iona t e d po l y s ty r e ne - d i v i n i l- be nz e ne S D V B )m e m b r a n e . T h e m e m b r a n e w a s e l u t e d w i t hm e t h y l e n e - c h l o r i d e , th e e l u at e w a s c o n c e n -t r a te d ( u p t o 1 m l ) u n d e r v a c u u m a n d a n a l y s e db y G C / M S . C o n t r o l o f e x t r a c ti o n a n d c o n c e n -t r at i o n p r o c e d u r e s w a s o b t a i n ed w i t h b l a n k sa nd s t a nda r d s o l u t i ons .

N-n i t ro so -amines : l i qu i d -l i qu i d e x t ra c t ion G C / M Sm e t hod ( S t a nda r d M e t hod N o . 64 10 B ) m od i f i e df o r e x t r a c t i o n a n d c o n c e n t r a t io n p r o c e d u r e s :a 2-1 sam ple was a lka l in i sed to pH 11 wi th 10NN a O H , f i l t e r e d on 0 . 45 - k t m c e l l u l o s e n i t r a t em e m b r a n e a n d e x t r a c t e d b y v a c u u m f i l tr a ti o no n a p r e v i o u s l y c o n d i t i o n a t e d C 18 m e m b r a n e .T h e m e m b r a n e w a s e l u t e d w i t h m e t h y l e n e -c h l o r i de , t he e l ua t e w a s c onc e n t r a t e d ( up t o1 m l ) u n d e r v a c u u m a n d a n a l y ze d b y G C / M S .C o n t r o l o f e x t r a c t io n a n d c o n c e n t r a t io n p r o -c e du r e s w a s ob t a i ne d w i t h b l a nks a nd s t a nda rds o l u t i ons .T he f o l l ow i ng a na l y t i ca l i n s tr um e n t s w e r e u s ed :

t ange nt ia l u l t r a f i l t r a t ion appa ra tus mo d. Sa r to-c on 2 a nd m od . S a r t oc on M i n i by S a r t o r i u s ;

op t i c m i c r os c o pe ( d i r e c t l igh t , pha s e - a nd d i f -f e r e n t i a l - i n t e r f e r e nc e - c on t r a s t )m o d . A x i o s k o pM C 8 0 b y Z e is s ;

f l u o r e s c e n c e m i c r o s c o p e m o d . B H 2 b y O l y m -pus ;

g a s c h r o m a t o g r a p h / m a s s s p e c t ro m e t e r ( G C /M S ) m o d . S a t u r n 3 b y V a ri an w i t h p u r g e an dt r ap a u t o s a m p l e r m o d . 3 0 0 0 b y T e k m a r ;

v a c u u m c o n c e n t r a ti o n a p p a r at u s m o d . A E S1000 by S a va n t ;

l iq u i d c h r o m a t o g r a p h / m a s s s p e c t r o m e t e r ( L C /M S ) m o d . A P I 3 0 0 b y P e r k i n E lm e r .

3 . R e s u l t s a n d d i s c u s s i o n3 .1 . P a r a s i t e r e m o v a l p e r f o r m a n c e

A s s a id , s e ve ra l c yc l e s w e r e r un a t U V dos e o f1 00 a n d 1 60 m W s / c m 2 f o r F a n d C L f e e d r e s -p e c t i v e l y to e v a l u a t e U V e f f e c t iv e n e s s t o w a r d ss e l e c t e d p a t h o g e n i c p a r a s i t e s ( G i a r d i a l a m b l i ac y s t s , C r y p t o s p o r i d i u m p a r v u m o c y s t s a n dN e m a t o d e s e ggs ) l i ke l y t o oc c u r in l oc a l w a s t e -w a t e r a n d a r e r e p o r t e d l y r e s i s t a n t t o c h e m i c a ld i s i n f e c t a n t s .T h e o c c u r r e n c e o f t h e s e p a t h o g e n s i n C L a n dF f e e d be f o r e a nd a f t e r U V d i s i n f e c t i on is r e po r t e di n T a b le 1 (a ve r a ge va l ue s ) .

N e m a t o d e s e g g s w e r e n e v e r f o u n d in t h e f e e d sa dm i t t e d t o d i s i n f e c t ion , c on f i r m i ng t he e f f e c t i ve -ness o f c la r i f ica t ion and f i lt r a tion s teps in r em ov ingc ons i s t e n t l y s uc h l a r ge a nd h e a v y pa r a s i t e s [ 15 ],b u t n o t t o w a r d s s m a l l e r o n e s l i k e G i a r d i a c ys t sa n d C r y p t o s p o r i d iu m o o c y s t s d e t e c t e d i n a p p r e c i -a b le n u m b e r i n fe e d C L a n d r e m o v e d o n l y i n p a rtby f i l t ra t i on , as e xp e c t e d [ 16] . I n t he s e c ond i t i onsU V r a d ia t io n w a s r a t h e r e f f e c ti v e in b o t h f e e d st o w a r d s b o t h p r o t o z o a n p a r a si te s w i t h a n a v e r a g er e m o v a l a r o u n d 6 0 a n d 6 5 % f o r G i a r d i a a n dC r y p t o s p o r i d i u m r e s pe c t i ve l y .

Table 1Selected parasites before and after UV disinfection ofclarified(CL) and clarified-filtered F) feeds (UV dose: 160and 100 mW s/cm respectively)Parasite Feed In Out % remov alNematodes CL 0 0 - -eggs (N/l) F 0 0 - -Giardia lamblia CL 345 156 55cysts (N/I) F 114 44 62Cryptosporidium CL 23 8 65Parvum oocysts (N/I) F 6 2 67

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L. Liberti et al. / Desalination 152 (2002) 315-324 31 9These resul ts cam e not unexpe cted as protozoancys ts a re res is tant species , requi r ing h igher UV

doses than bacter ia and v i ruses [17] . Accordingto l i te ra ture da ta , UV doses lower or s imi lar tot h o s e i n v e s t i g a t e d ( a r o u n d 6 0 , 8 0 a n d 1 2 0 -180 m W s/cm 2 ) a r e c l a ime d to p roduce 80 , 90 and99% inac t iva t ion o f G i a r d i a cys ts [18-20] andC r y p t o s p o r i d i u m ooc ys t s [21 ,22 ] i n d r ink ingw a t e r . T h e m u l t i p l e b a r r i e r c o n c e p t i n v o l v i n gclar i f ica tion and f i lt ra t ion (p lus eve ntual ly GA Cadsorp t ion ) p r io r t o U V d i s in fec t ion undoub ted lyappea r s t he m os t e f f ec t ive approach fo r com ple t epa rasi te r emov a l i n wa te r and was t ew a te r t rea t-ment [20] .I t must be poin ted out tha t the proved occurrenceof so me p ro tozoa in t he d i s in fec t ed e f fluen ts doesnot cau se res t r ic t ion for the i r reuse in agr icul ture .In fact , according to the W HO guidel ines [23] , theonly paras i tes of concern are in tes t ina l nematod es(M AC < 1 egg/ l ) , never found dur ing th is inves ti -ga t ion . How ever , these la t te r a re in tended to serveas indica tor organism s for a l l paras i t ic pa thogen sand i t is im plied that al l helminth eggs and protozoancys t s shou ld be r emoved to t he s ame ex t en t t oavo id t he r i sk o f w a te rbo rne d i sease ou tb reaks .3 .2 . Dis in fec t ion by -produc ts fo rm at io n

As fo r even tua l fo rma t ion o f UV d i s in fec t ionby-p roduc t s du r ing d r ink ing wa te r p roduc t ion , i ti s gene ra l ly a s sumed tha t modera t e u l t r av io l e ti r rad i a ti on ( 1000 roW s/cm 2) indica ted the nee d fo r fur ther informa t iona b o u t U V p r o m o t e d t ra n s f o rm a t i o n o f o rg a n i ccom pound s i n mun ic ipa l was t ewa te r s [24 ,25] .

On the bas i s o f pho tochem is t ry fundamen ta l s ,in fac t , i t can not be e xclud ed tha t UV i r radia tionofw astew ater could affect the identi ty o f he organics u b s t a n c e s t h r o u g h e i t h e r d i r e c t o r i n d i r e c t

in t er ac t ion fo rming po ten t i a ll y t ox i c by -p roduc t s[26 , 27 ] . I n t he fo rmer case , a mo lec u le know n asa c h r o m o p h o r e m a y b e c h e m i c a l l y m o d i f i e d a s ar e s u l t o f d i r e c t ra d i a t i o n a b s o r p t i o n . I n d i r e c tpho to lys is may o ccu r whe n UV rad i a t ion ac t s ona s p e c i e s k n o w n a s a p h o t o s e n s i t i s e r w h i c hs t rong ly abso rbs t he r ad i a t i on ene rgy and theresul t ing h ighly energet ic species in terac ts wi tha n o t h e r m o l e c u l e p r o d u c i n g a c h e m i c a l t r a n s -formation [28,29].

Cons ide r ing tha t am ino- and phen o l i c -de r iva -t ives (chrom opho res) as wel l as n i t ra te /n i t r ite ionsand hu m ic mater ia l s (photosens i t isers ) a re speciescom mo nly occu r ring in mun ic ipa l was t ewa te r andpotent ia l ly capable o f reac t ing [30], n i t ro-phenolsand N-n i t ro so -amines w ere spec i f ica l l y s ea rchedfor in this investigation as possible DB Ps fo llow ingUV i r radia t ion .

F i gs . 2 - 5 s h o w t h e c o r r e s p o n d i n g G C / M Schromatograms o fF and CL feeds be fo re and a f te rUV d i s in fec t ion (doses o f 100 and 160 m W s/cm 2respect ive ly) .

T h e n e a r l y t o t a l o v e r l a p p i n g o f a l l s p e c t r aseems to exc lude the fo rma t ion o f bo th ha rm fu lN-derivatives abo ve the instrumental detec tion limit(0.01 ppb) in the con di t ions inves t iga ted .A poss ib l e exp lana t ion cou ld be t he fo rma t iono f n o n -v o l at il e D B P s ( N V D B P ) w h i c h a r e n o t d e -t ec ted by GC/M S bu t on ly by LC /M S (o r M S /M S)ana ly ti ca l techn ique . A spec i a l expe r imen t wasca re fu lly p lanned to chec k th is hypo thes i s a t l abscale . In par t icular , in order to max im ize the pro-babil ity o f detecting the eventual N V D B P formation,a 500-ml sample o f CL feed was irradiated in a glass-ba t ch -UV reac to r u s ing pu rpose ly an ex t r eme lyhigh UV dose (25 ,000 mWs/cm2). Sam ples beforeand a f t e r t he i r r ad i a t i on were concen t r a t ed 25t imes by lyoph i li za ti on and pos t - co lum n in j ec t edin to a LC-M S spec trome te r . The ob ta ined massspect ra repor ted in Fig . 6 , once again , do not sh owany s igni f icant d i f ference betw een i r radia ted andnon- i r r ad i a t ed samples , exc lud ing the even tua lf o rm a t io n o f N V D B P s e v e n u n d e r t h e e x t r e m eir radia t ion adopted dur ing the exper iment .

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320 L . L i b e r t i e t al , / ' D e s a l i n a t i o n 1 5 2 ( 2 0 0 2 ) 3 1 5 - 3 2 4

i

u |

1 2 0 0Fig. 2. Nitro-phenols search: GC/M S spectra o f F feed be fore and after LJV disinfection (100 m Ws/cm~),

If l ~ 1 2 0 0 16~1~ 2 0 ~ 2,400

Fig. 3. N-nitroso-amines search: GC/MS spectra o f f feed before and after UV disinfection (100 mW s/cmZ).

I ft 5 0 0 t f l ( ~ 2 1 8 6.h! , !

9~ t~9 J2 4 0 ~Fig. 4, Nitro-phenols search: GC/M S spectra of CL feed before and after UV disinfection (160 mWs/cm2 ).

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L. Liberti e t al . / Desalination 152 (2002) 315-324 321

I ' ' I ' I = ' ' ' ' - - - ' ' '8 0 0 : 1 2 , 0 0 1600 2 0 0 0, , , | | ' - - !

2 4 0 0Fig. 5. N-nitroso-amines search: GC/M S spectra of CL feed before and after UV disinfection (160 mWs/crn2).

5 , 4 1 64,Se6$ . 6 d2 . 7 d "

. 8 d -g . o t S ,

I

,1

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1"~o 2110 310 4 1o 49 0 5110 11,30 TOO

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G e S " 1 7 1 , 3

It6"~ " 4 e l l l , d , : '4S.3z* * zl o ~ io 4/0 410 s~ ~ Tc~ ,7*m / I ,

Fig. 6. P ost injection LC/M S spectra of iyophilizated samples of C L feed before and after UV irradiation (25,000 mW s/cm~).

T h e a b o v e e v i d e n c e s a r e i n g o o d a g r e e m e n tw i t h t h e c o n c l u s i o n s r e p o r t e d f o r s i m i l a r i nv e s ti -g a t i o n s t a t in g t h a t U V - p r o m o t e d t r a n s fo r m a t i o no f c h e m i c a l c o m p o u n d s , a t l ea s t in c l e a n w a t e rs ,r e q u i r e s m u c h h i g h e r d o s e s t h a n n e c e s s a r y f o rm u n i c i p a l w a s t e w a t e r d i s i n f e c t i o n [ 3 1 - 3 5 ] .

3 .3 . C o s t e s t i m a t e sT o a s s es s t h e e c o n o m i c f e a s ib i l it y o f U V d i s in -

f e c t io n t r e a tm e n t f o r w a s t e w a t e r r e u s e i n a g r i c u l tu r e ,o p e r a t i o n a n d m a i n t e n a n c e ( O & M ) c o s t s w e r ep r e l im i n a r i ly e s t i m a t e d o n t h e b a s i s o f t h e e x p e r i -

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322 L. Liberti et al. / Desalination 152 (2002) 315-324m e n t a l r e s u l t s o b t a i n e d b y r e f e r e n c e t o th e o p t i m a lU V d o s e f o r e a c h f e e d t h a t p e r m i t t e d t h e a c h i e v e -m e n t o f t h e ta r g e t t o ta l c o l i f o r m s s t a n d a r d o f2 C F U / 1 0 0 m l , i .e ., 1 0 0 a n d 1 6 0 m W s / c m 2 f o r F a n dC L f e e d s r e s p e c t i v e l y .

T h e f o l lo w i n g a s s u m p t i o n s w e r e m a d e : O & M c o s t s a c c o u n t e s s e n t i a l ly f o r e l e c tr i c

p o w e r c o n s u m p t i o n a n d l a m p r e p l a c e m e n t ,i n c l u d i n g al s o m a i n t e n a n c e r e q u i r e m e n t s a n dm i s c e l l a n e o u s e q u i p m e n t r e p a ir c o s ts

p o w e r c o n s u m p t i o n o f U V e q u i p m e n t s is3 .1 k W h

a v e r a g e e l e c t r i c i t y c o s t is t~ 0 . 0 6 5 / k W h U V l a m p (t~ 4 5 e a c h ) r e p l a c e m e n t is b a s e d o n

8 7 6 0 h o f u s e .A s s h o w n in T a bl e 2 , O & M c o s ts o f U V a d -

v a n c e d d i s i n f e c t i o n o f t h e i n t e r m e d i a t e ( c la r i fi e d ,C L ) a n d t h e f u l l t e r t i a r y t r e a t e d f e e d ( c l a r i f i e d -f i l t e r e d , F ) a m o u n t e d t o t~ 3 5 a n d t~ 1 7 . 5 / 1 0 0 0 m 3r e s p e c t i v e l y . T h e a b o v e e s t i m a t e s d o n o t i n c l u d ec a p i ta l c o s t s a n d c a n b e i n f l u e n c e d b y v a r ia b l e ss u c h a s f e e d q u a l i t y , p l a n t c o n f i g u r a t i o n , p l a n t s i z e( s c a l e f a c t o r ) a n d m a r k e t s i t u a t i o n .

C o s t e f f e c t iv e n e s s o f U V a d v a n c e d d i s i n fe c t io n ,i n p a r t i c u l a r o f F f e e d , i s e v i d e n t c o n s i d e r i n g t h a tc h l o r in a t i o n o f m u n i c i p a l w a s t e w a t e r j u s t f o r s e ad i s c h a r g e i n c o m p l i a n c e w i t h I t a l i a n r e g u l a t i o n s( 2 0 , 0 0 0 C F U / 1 0 0 m l f o r t o t al c o l i f o r m s ) a t W e s tB a r i t r e a t m e n t p l a n t c o s t s a p p r o x i m a t e l y ~ 5 /1000 m 3.

4 . C o n c l u s i o n sT h e e x p e r i m e n t a l r e s u l t s o f a 9 - m o n t h p i lo t -

s c a l e ( 1 0 0 m V h ) i n v e s t i g a t i o n , c a r r i e d o u t a t t h eW e s t B a r i ( S . I t a l y ) m u n i c i p a l w a s t e w a t e r t r e a t -

m e n t p l a n t, f o c u s e d o n p a r a s it e r e m o v a l a n dd i s i n fe c t i o n b y - p r o d u c t ( D B P ) f o r m a t i o n d u r i n gt h e U V d i s i n f e c t io n o f c l a r if i e d ( C L ) a n d c l a r i f ie d -f i lt e r e d ( F ) s e c o n d a r y e f f l u e n t s a t d o s e s ( 1 6 0 a n d1 00 m W s / c m 2 r e s p e ct iv e l y ) n e c e s s a ry f o r a c h i e v i n gt h e to t al c o l i f o r m s s t a n d a rd o f 2 C F U / 1 0 0 m l f o ru n r e s t r i c t e d r e u s e o f w a s t e w a t e r i n a g r i c u l t u r e ,p r o v i d e d t h e f o l l o w i n g i n d i c a t i o n s :

1 . A t t h e a b o v e d o s e s , U V r a d i a t io n w a s r a t h e re f f e c t i v e i n b o t h f e e d s t o w a r d s p r o t o z o a n p a r a s i t e sl i k e G i a r d i a l a m b l i a c y s t s a n d C r y p t o s p o r i d i u mp a r v u m o o c y s t s ( a p p ro x . 6 0 a n d 6 5 % r e m o v a lr e s p e ct i v el y ) ; N e m a t o d e s e g g s w e r e n e v e r f o u n di n t h e f e e d s a d m i t t e d to d i s i n f e c t i o n b e c a u s e a l r e a d yr e m o v e d b y c l a r if ic a t io n a n d s e d i m e n t a t i o n ;

2 . T h e m u l t i p l e b a r r i e r c o n c e p t i n v o l v i n gc l a r i f i c a t io n a n d f i l tr a t i o n p r i o r t o U V d i s i n f e c t i o nw a s c o n f i r m e d t o b e t h e m o s t e f fe c t i v e a p p r o a c hf o r c o m p l e t e p a r a s it e r e m o v a l i n w a s t e w a t e r t re a t -m e n t ;

3 . N o n e o f t h e N - d e r i v a t i v e s ( i . e. n i t r o - p h e n o l sa n d N - n i t r o s o - a m i n e s ) s e a r c h e d f o r af te r U V d i s -i n f ec t i on o f b o t h fe e d s w a s d e t e c t e d b y G C / M Sa n a l y ti c a l te c h n i q u e w h i l s t L C / M S a n a l y s e se x c l u d e d a l s o t h e f o r m a t i o n o f n o n - v o la t i le D B P s ,s u g g e s t i n g t h e a b s e n c e o f d e t e c ta b l e p h o t o -c h e m i c a l r e a c t i o n s a t U V d o s e s u s u a l l y u s e d i nw a s t e w a t e r d i s in f e c ti o n ;

4 . O & M c o s ts o f U V d i s in f e c ti o n a v e r a g e dt~ 1 7 .5 a n d t~ 3 5 / 1 0 0 0 m 3 f o r F a n d C L f e e d r e s -p e c t i v e l y .

F u r t h e r i n v e s t i g a t i o n i s p l a n n e d t o a s s e s s U Ve f f e c t iv e n e s s t o w a r d s v i r u se s , t o e x c l u d e U Vp r o m o t i o n o f o th e r D B P s , t o p r e v e n t e f f l u e n tr e c o n t a m i n a t i o n ( b a c t e r i a p h o t o r e a c t i v a t i o n b yc e l l r e p a i r a n d r e g r o w t h ) a n d t o e v a l u a t e p o s s i b l e

Table 2Cost estimates for U V disinfection of CL and F feeds at West Bari pilot plantFeed UV dose, Total coliforms target achieved, O& M costs, t~/1000 m 3

m W s / c m2 CFU /100 m l Electr ic power Lamp replacement TotalF 100 I 6.7 10.6 17.3CL 160 1 13.5 21.3 34.8

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L. Liberti et al. / Desalination 152 (2002) 315-324 323

s y n e r g y a n d / o r c a t a l y ti c e f f ec t s o f U V r a d i a ti o n w i t hl o n g - a c t i n g c h e m i c a l d i s i n f e c ta n t s s u c h a s H 2 0 2.

R e f e r e n c e s[ ! ] State o f California. Wastewater Reclamation Criteria.California Administrative Code, Title 22, Division 4,California D epartment o f Health Services, Sanitary

Engineering Section, Berkeley, CA, 1978.[2] T. Asano, Wastewater Reclamation and Reuse. Tech-

nomic, Lancaster, 1998.[3] A. Pros t , Hea l th r i sks s temming from wastewaterreutilization, W at. Quality Bull., 12 (1987) 73.[4] H.V. Sm i th , L.G. Rob er t son and J .E. Ong her th ,Cryptosp oridiosis and G ardiasis: the impact of water-bo rne t r a nsmi s s i on , J . W a t e r S RT-AQUA, 44 (4 )(1995) 258.[ 5 ] J.J. Rook, Form ation ofh alof orm s during chlorinationo f natural waters, Wat. Treat. Examin., 23 (1974) 234.[6] R.A. Minear and G.L. Am y, Disinfection By-Productsin Water Treatment, Lewis Publishers, New York,1996.

[7] V. Lazarova, P. Sav oye , M.L. Janex, E.R. BlatchleyIII and M. Pomm epuy, Advanced was tewate r d is -i n fe c t i on t e c hno l og i e s : s t a te o f t he a r t a nd pe r -spectives, Wat. Sci. Technol., 40(4-5) (1999) 203.

[8] L. Liberti and M. Notamicola, Advanced treatmentand disinfection for municipal wastewater reuse inagriculture, W ar. Sci. Technol., 40(4 -5) (19 99) 235 .[9] L. Liberti, A. Lope z and M. Notarnicola, Disinfectionwith peracetic acid for dom estic sewage re-use in agri-culture, J. Ch. Instn. Wat. Envir. Mangt., 13(4) (1999)

262.[10] L. Liberti , M. No tamico la and A. Lopez, Advancedtreatment for municipal wastewater reuse in agri-culture. III - Oz on e disinfection, O zon e Sci. Eng.,22(2) (2000) 151.[11] L. Liberti, A. Lopez, M. Notarnicola, N. Bamea, R.Pedahzur an d B. Fattal, Com parison o f advanced dis-infecting methods for municipal wastewater reuse inagriculture, W at. Sci. Technol., 42 (1- 2) (20 00) 215.

[ 12] L. Liberti, M. Notamicola, A . Lop ez and (2 Boghetich,Advanced treatment for municipal wastewater reusein agriculture. UV disinfection: bacteria inactivation,J. Water SRT-AQUA, 50(5) (2001) 275.

[13] Standard M ethods for the Examination o f Water andWastewater. 19 th ed., Am erican Public Health Asso-ciat ion/American Water Works Associat ion/WaterEnviron men t Federat ion, W ashington, DC, 1995.

[14] F. Portincasa, G. Torchietti, F. Donadio, D. C arnimeo,M.A. Panaro, S. Lisi, F. Maddalena and O. Brando-nisio, Metho d for determination o f Giardia cysts andCryptosporidium oocysts in water, Igiene moderna,107 (1997) 543 (in Italian).[15] D.C. Watson, M. Satchwell and C.E. Jones, A studyo f he prevalence of parasitic helminths eggs an d cystsin sewage sludge disposed of o agricultural land, W at.Poll. Control, 82 (1983) 285.

[16] Z. Bukhari, H.V. Smith, N. Sykes, S.W. Hum phreys,C.A. Pa ton, R.W.A. Gi rdwood and C.R. Fr icker ,Oc c ur re nc e o f Cryptosporidium spp ooc ys t s a ndGiardia spp cysts in sewage influents and effluentsfrom treatment plants in England, W at. Sci. Technol.,35 (11-12 ) (1997) 385.

[17] R.L. W olfe, Ultraviolet disinfection o f potable w ater,Environ. Sci. Technol., 24(6) (19 90) 768 .[18] E.W. Rice and J.C. Hoff, Inactivat ion of Giardialamblia cysts by ultraviolet irradiation, App l. Env iron.Microbiol., 42 (1981) 546.[19] D.A. Carlson, R.W. Seabloom, F.B. DeWalle , T.F.Wetzler, J. Engeset, R. Butler, S. Wangsuphachart and

S. W ang, Ultraviolet disinfection of w ater for sm allwater supplies. Project summ ary. EPA/600/S2-85/092,Office of Research and Dev elopm ent, US Env iron-mental Protection Agency, Cincinnati, OH, 1985.

[20] P. Karanis, W.A. Maier, H.M . Seitz and D . Schoenen,UV sensitivity of protozo an parasites, J. Water SRT -AQU A, 41(2) (1992) 95.[21] M.E. Ransome, T.N. Whitmore an d E.G. Carrington,Effe ct of disinfectants on the viab il i ty of Crypto-sporidium parvum, War. Suppl., 11 (19 93 )75 .

[22] A .T. Camp bell, L.J. Robertson, M .R. Snow ball andH.V. S mi th , Ina c t i va t i on o f ooc ys t s o f C r yp to -sporidiumparvum by ultraviolet irradiation, Wat. Res.,29(11) (1995) 2583.

[23] WH O. Health guidelines for the use ofwa stew ater inagriculture and aquaculture. Technical R epo rt Series778, W orld Health O rganization, Geneva, Switzerland,1989.[24] K. Nick, H .F. Scholer, G. Mark, T. So ylemez, M.S.Akhlaq, H. -P . Schuchmann and von C. Sonntag,Degradation o f some triazine herbicides by UV radia-tion such as used in the UV disinfection o f drinkingwater, J. Water SRT-AQUA, 41(2) (1992) 82.[25] M. Otaki and S . Ohgaki , Photochemica l decom-position of organo-chiorine com poun ds by a m ediumpressure UV lamp. Proc . Wate r Qua l i ty In te rna-t iona l '94 , IAWQ 17th Bienna l In te rna t iona l Con-ference, Budapest, Hungary, 199 4, p. 11 0.

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