s0048-9697(81)80062-9] F. Fiessinger; Y. Richard; A. Montiel; P. Musquere -- Advantages and...

8/17/2019 s0048-9697(81)80062-9] F. Fiessinger; Y. Richard; A. Montiel; P. Musquere -- Advantages and Disadvantages of Ch…

1/17

The Science

of

he Total Environment

1 8

198 1) 245--~261

Elsevier Scient i f ic Pu blbhing Company, Amsterdam - - Pr inted in Th e Ne ther landi

4 5

A D V A N T A G E S A N D D I S A D V A N T A G E S O F

Ci~HICAL

O X I D A T I O N A N D D I S I N F E C T I O N B Y O Z O N E A N D

CHLORINE DIOXIDE

F. FIESSI NGER (I), Y, RICI~RD (2) , A. HONTIEL (3) and P, HUSQUE RE (I)

( I ) Soci~t~ Lyonnaisc des E~ux, 4 5 rue Gortamber~, 75Ol6 Paris, France

(2) SociOc~ D e g r ~ m o n t , B . P .

4 6 ,

9215f

uresnes

Cedex, France

(3) Service de Cont r~le des Eaox de in Villa de Paris, 144 avenue P a u l V a i l l a n t

C o u t u r i e r , 7 5 0 1 4 P a r i s , France

A B S T R A C T

O z o n e a n d c h l o r i n e d i o x i d e p re s e n t d e f l n i t e a d v a n t a g e s a n d d i s a d v a n t a g e s o v e r

chlorination. Clll0rlnatlon , partlcu larly for the removal of m maonia and the main-

tenance

o f a d i s i n f e c t a n t r e s i d u a l i n t h e

d is t r i u t ion

s y s t e m

has

d e c i s i v e a d v a n -

t a g e s a nd w i l l b e d i f f i c u l t t o r e p l a c e . O zo ne a nd c h l o r l n e d io .x ld e s ee m t o p r o d u c e

f e w e r c a r c i n o g e n i c b y - p r o d u c t s b u t th e r i s k f v r a c u t e t o x i c i t y , e s p e c i a l l y f ro m

t he c h l o r i t e s w h ic h f o l l o w c h l o r i n e d i o x i d e , i s h i g h e r t h a n w i t h c h l o r i n e .

C h l o r i n e d i o x i d e a nd m o re p a r t i c u l a r l y o z on e sh o u l d be c o n s id e r e d a s u s e f u l

compleme nts to chlorination,

buc

n o s t r o n g o x i d a t i v e t r e a t m e n t s h o u l d b e

a p p l i e d

b e f o r e

m o s t

o f

t h e o r g an i c m a t t e r

has

b e e n r e m o v e d .

INTRODUCTION

Co mp ar i s o n w i . t h Ch l o r . ~n e

T h e a w a re n e ss o f t h e p o t e n t i a l h e a l t h h a z a r d s c r e a t e d b y t h e p r e s e nc e o f h a l o -

g e n a t e d c o m p o u nd s ' i n d r i n ki n g w a t e r h a s l e d p u b l i c au t h o ri t i es a n d w a t e r s u p p l i r a

t o i n v e s t i g a t e a l l p o s s i b l e m ea ns o f . r e d u c i n g th em , N ~ e r o u s s t u d i e s ~ h ro u gh o ut

t h e w o r l d (5 ) h a v e le d t o t h e e o n c l u s i o n t h a t h ig h c h l o r l n e d o s a g e s i n w a [ e r s

c o n t a i n i n g o r g a n i c r - e c u r a o r s s h o u l d b e a b a n d o n e d . T he se w a t e r s , h o w e ve r , m u s t b e

d i s i n f e c t e d , a n d v e r y o f t e n r e q u i r e , a n o x l d a t l o n t r e a t m e n t f o r t he ', ~ em o v a l o f

t u r b i d i t y , t a s t e o r c o l o r . ' A l t e r n a t i v e s t o c h l o r l n e h a ve t h e r e f o r e b ep n s o u g ht ,

a nd a mo ng t h e s e , c h l o r i n e d i o x i d e a n d o ~ o ne

a r e

t h e ~ o s t a ~ t r a c t i v e : ' ~ n ~ a d d l t l o n

t o p r o d u c in g l e s s o x i d a t i o n b y - p r o d u c t s f : t h e y h a v e a g r e a t e r o x i d i z i n g p o t e n t i a l

and seem to inactivate ba'c~erla and viruses more readily than chlorine, Several

\

e x c e l l e n t a r t i c l e s ~ h av e a l r e a d y b e e n d e d i c a t e d tO t h e a d v an [ a g e s a n d d i a a d v a h t a g e a

o f ' t h e s e r e a g e n t s ( $ , ' 8 , 9 , - ' 1 2 ) ~ T h e ' p r e s e n t p a p e r ' d o e s nO t a t ~ e w p t - to p r e se n t -

a ny n e~ f i n d i n g s o n o x i d a t i o n a nd d i s i n f e c t l o n , o r t o d i s c u s s t h e h e a l t h a s p e c t s

0048.969718II0000-00001502.50 © 1981 FJemvierScie nt i f ic Pub l lsh ing Company


2/17

24G

whlch

nru

tr ea te d elst , where il l th is sympoaltaa, but rnvrely tri es to poi nt out

~or0e vt~ry pra ~t l col conc lusi ons about the use of these d if f er ent oxida nts in a

surf ace water t reat ment pro ces s , th~l~ may he h~lpf ul to a g a tor t r ( ,a tm e. t p la nt

o p e r a t o r .

Oxida t ion and b i s ingec t ion

I t i s d i f f i cu l t to separa t e the ox id iz ing aa~d the d i s in fe c t in g capa c i t i e s .

Ozone is the s t ron ges t ok the thre e oxidnnts the~ corses chl or i ne dioxide and

f in a l ly ch lo r ine . TIw germic i da l e f fec t l ve l~ess goes , o f course , in the same o rde r ,

In the course of th is paper

th

term~ oxidan t and dls i nfee ta~l t wi l l be used i nte r-

changab ty ~ i t l~ hoeever , a p re fe renc e fo r the l a t t e r ~hen i t i s used in a f in a l

un i t p rocesg .

P o s i t i o n of Oxidat.ion 9ud. ~i~ i.n rsc sio n in the Treatmen._ t Pr oc es s

The e f fe c t o f an ox idan t i5 c los e ly re la te d to the po in t a t vh ich i t i s app l ied

i n t h o over a l l t~eatment p rocess . F igure I su r~nar izes the va r ious poss ib le po s i -

t ions in a f a i r ly cca~p le te su r f ace ~a te r t r ea tmo. t p r ocess , The ox id a t iv e ro le

is o~ cou r ,e decreased when the reagen t i s in t roduced a t the end ~£ the process .

F igure I a l so ind i ca te s tl~e po . s slb le combina t ion o f severa l ox ida n t s . An exce l -

l e n t s e qu e nc e , f o r i n s t a n c e , i s c l a r i f i c a t i o n , o z o n a t i o n , g r a n u l a r a c t i v a t e d

ca rbon (G,XC) f i l t r a t i~ r t and f i rt a i d i s in fe c t io n wi th ch lo r i ne . T h i s genera l case

of water t reatme,at ~ i t l serve as a bas is for the comparison of t lie three dif fe ren t

o x i d a n t s , . .

R A W W A TEH

@ -- - - I

¢ i L x v o A T o N

[ _ o , S ' ' C ] , o N - J

POTABLE WATER

~ i g . l , , P o a l t i o n o f o x i d a t i o n t r e a t m e n t s i n a g e n e r a l . s u r f a c e w a t er tr e a t m e n t process


3/17

24"1

i l l l l ( l ]

RAW WATER |

I 8~ AK _ POIWT I

~ + )

sl~.~O t LTm,tmN I

/ ~ ~ - - I ~o- ° j

- J, - i] - I I

.o i+~_ t , t , , . J i "_ ._= ,~L, , , ,o , i ~ I ,o , , L , , , , , o . l

i

( ~ - -

. , +,

l PILOT

LIW| N'I LINE II ' l LINI I1 3 ll~ fl N I

Fig. 2. General |ay out

o (

t li¢ Horsang-sur-Seine ra te r treatment proce ss.

v._~'C, LUL-

P I|¢ Liae Isdvstrmal L ae

L F lt I f L r lt tr I ~ ml=w J

[a,,.,,, . . I I

~ ~

~ . i

gig. 3. C,¢nt -~ lay-ou t o£ the Vigneux-sur-Seine water treatment pl an t .


4/17

4B

.The Horsan~ and.Vjgnet~ Experiments

Host of the results presented here come from the authors experiments conducted

pri mar i l y a t two plant ~ t rea t i ng the water f rom the Seine in the Par is area . The

general layout of these two plants i s given i~ Figures 2 and 3.

The Norsang pl an t has been u~ed fo r severa l yea r s to s tudy the e f fe c t o f ozone

CoAC and pre ch lo ri na ti on At the Vigneux pl ant and on the pil ot act -up which goes

~ i th i t s tud ies a rc p rese n t ly be ing made on ch lo r ine d iox ide and fu r t he r r e su l t s

will be p resen t ed in the nea r fu tu re

~SE OF OXIDANT AS PRETREATHENTS

In a recent article (4) the outhors have discussed the various advantages and

d isadvan tag es o f us ing ch lo r i ne as a p re t rea~nenc The i r main on lus ion i s tha t

prechlorlnation should be abandoned,

bu~

in order to control the final disinfectant

consumption and its residval by-products, granular activated carbon and possibly

ozone should be included in the treatment process. Abandonlng prechlorlnation,

bo~ever, creates plan~ operational problems which explain much of the reluctance

o f o p e r a t o r s t o do so

Stability

Ozone decomposes quickly in water (Figure 4) and thus has no lastlnq effect.

° l

O

0 I. T

O .5 10 15 20 ~

Fig. 4. Decrease in residual ozone

with time - Seine water

Chlor i r e and ch lo r in e dioxi de are comp arat ivel y much more s t abl e Chlor ine

dioxide, however, is very sensitive to,l~ght. Figure 5 represents the chlorine

dioxide and chlorlte concentrations in dark.(A) and light (B). The differences,

due

only to

clouds ~nd sunlight, are in R

5

to I

ratio

which makes the residual

levet very difficult to control in open-air ciarifiers and filters.-In comparlson,

chlorlne~s fluctuations are only in a 20 Z.range. This L~I a major disadvantage

of CIO and in many cases, would be a sutficicnt reason for not using it as a

pretreatment. One may object that the Wo~ks could be covered (th6y arep in fact,

in the Vigneux experiment)..but in that case the gro~th of algae, ~hlch is the,

most common reason for using preoxldation, could be e£{ectlvely controlled and

the need for ¢102 pretreatmenC would be greatly reduced


5/17

F i g 5

2 4 9

O.S

0

2

I

Re,;du,t ew doq 'u | I I ~ .~t~. ' ' ' ' ~ - "e

F ~ . , / / . /

t o : I

/

R e | , d v ¢ J e f j ' d , l n t

m i l l

0. S ~ :.~..L__ ', " +

~ i ~ " ' * - - ' ' " - ~ - ~

. ~ J t t l | ~ 4

1 i

1 2 5 4 5 6 7 | 9

clot Ipphod m |ll

C h a ng e s i n r e a L d u a C 1 0 2 a nd b y - p r o d u c t s . i n t h e d a r k ( A ) a n d a t s u n l i s h l : ( B ) ,

T AB LE : I : A l g a l c o u ~ c s i n w a t e r t r e a t e d w J l :h C 1 2 a n d C l O 2 ,

TREATMENT,

RAW WATER

• , L

OXYDANT DCSE

PPM

C lO 2 .i-

CLARIFICATION

C] 2 + CLARIFICATION

C10.

+ CLA RJ F J C.A T |ON

z

SAND FILTRATION

•

SJ~tPLING

P OINT '

1

C 2

CIO2

3

3T

4

liT

- OTAL ALGAL COUNT / ML. -

1 6 . 7 . 8 o t 2 2 . 7 . 8 o j , o . 7 . 8 o

..I

600 .

0 . 9 5

6

0

d,

1 2 0 0

5

1 1 5

9 .

0

} 0

1 2 0 0

5 . 5

4 . 1 5

3 3

21

CI + CLARIFICATION

• +2 SAND FILTRATI~N


6/17

25

A ~o

C a n t

r~l

An i m m e d i a t e r e s u l t o f e l i m i n a t i n g p r e e h l o r i n a t i o n - e s p e c i l t l l y d u r i n g t h e

w a rm p , , r i o d - i s a p r o l i f e r a t i o n o f a l g a e i n t h e u n c o v e r e d c l a r i f l e r s a n d f i l t e Y s .

I n a d d i t i o n t o f o u l i n g t h e w o r k~ c o n s i d e r a b l y t h i s g r o w t h

may

i n t e r f e r e w i t h

c l a r i f i c a t i o n aL ~d s h o r t e n th e f i l t e r r u n s .

B e c a u se o f i t s r a p i d d i s a p p e a r a n c e , o z o n e c a n n o t b e a v i a b l e a l t e r n a t i v e t o

c h l o r i t l e . C h l o r i n e d i o x i d e - a s i n d i c a t e d i n T a b l e I - d o e s no t s e e m a s e f f i c i e n t

a s c h l o r in e i n c o n t r J l l i n g a l g a e g r o w t h . O ne m ay o b j e c t t h a t t h e d o s a g e s a r e n o t

e x a c t l y c o m p a r a b l e . B u t h ow c a n w e c o m p a r e tl ~e m ? T h i s i s a p o i n t ~ h a t w e s h a l l

d i s c u s s l a t e r , T h e r e l a t i v e l y l o w e r e f f e c t i v e n e s s o f C IO 2 m ay a l s o b e r e l a t e d

t o i t s g r e a t e r i n s t a b i l i t y i n s u n l i g h t t h a t w e h a v e ' ~ m e n t i o n e d e a r l i e r .

C l a r i f i e a t i o n

I t h ~ s b g e n s h ow n ( 4 ) t h a t t h e

u s e

o f p r e c h l o r i n a t t o n i m p r o v e s t h e t u r b i d i t y

of water by some IO . Chlorine dioxide seems to have a very comparable effect.

O z o n e I ta s b e e n p r e s e n t e d a s a g o o d m i c r o f l o c c u l a n t ( 3 ) . I t o f c o u r s e p r e c i p i -

t a t e s i r o n a n d m a n g a n e s e ( e l 2 a n d C 10 2 a l s o , s e e t a b l e 4 ) , b u t i n c a s e s o f w a t e r

w i t h a h i g h o r g a n i c c o n t e n t i t a l s o e n h a n c e s t h e f l o c f o r m a t i o n a n d t h e s u b s e -

q u e n f c l a r / f i c a t i o n . T h i s e f f e c t

ks

s u ~ a r i z e d i n F i g u r e 6 : t h e b e : , . , f i c i a

e f f e c t o f o z o n e i s m o r e i m p o r t a n t i f a l ow c b a g u l a n t ( u n d e r ) d o s a g e i s a p p l i e d .

This improvement of turbidity can be as high as 20 Z but will not generJflly

j u s t i f y t h e u s e o f a s p e c i f i c o z o n a ~ i o n u n i t , T h i s m a y , h o w e v e r , b e a n i n t e r e s -

t i n g a p p l i c a t i o n o f a n e x c e s s p r o d u c t i o n c a p a c i t y - o r o f f - g a s e s - o f a n o z o n a -

tion unit used primarily for intermediate oxidation (see later), particul arly

since the doses used for good clarification in pretreatment are gene rally small.

T h i s e f f e c t h a s a l s o b e e n s ho w n f o r o r g a a i e r e m o v a l ( 4 b i n ) .

3.0 ~ ~ CL AR IFIE D WATER (NO O ]

. _ CLARIFIED

: k ~ _ _ . ' ~ W ATER ( I P P M 0 3 l

p.' FILTERED

WATER ( NO 03 ]

2,0 ~ , . - - 4- - FILTERED WATER (I PPM g3 )

~ ,

1.0 ' ._ _. , m . •

i~'~l +,,,,.., , • . . . . .

O -, ' ' j . . . . , u' I

O 20 40 | 0 I l l

C OA GU LA N T D OS E - P P M W A C

Fig. 6, Effect of pre-0zonation

o n

water clarification. La

S e i n e

at Croissy, Ref.

3


7/17

9-81

Elimina t ing prechlor ina t ion causes n s l igh t decrease In the f i l t e r s p rodu c t ion

ca pa ci ty . This . of course, v ar ie s widely with tlm type of works, the fi lt er medium

a n d t h e f i l t r a t i o n v e l o c i t y , I t s e e m s ( 4) t o c a u s e a re a l p r o' b l e m d u r i n g t h e p e r i o d s

of peak f low- mrs only . This shor tening of the f i l te r runs i s par t ty re la ted to

the presence of plankton, and one may expect a le sse r ef fi cie ncy of Chlorine dioxide

,r.;-

'

and ozone.

T a b l e 2 g i v e s

a n

e x a m p l e o f f i l t e r r u n s w i t h C I 2 a nd C I O 2 P r e t r e a t m e n t s

a t V i & n e u x , T h e r e i s g e n e r a l l y a h i & h e r h e a d l e s s b u i l d - u p o n f i l t e r s r e c e i v i n g

wat er . t re a te d wi th C10 2 . On the o the r hand, the t urb i d i ty of the . f i l te red wat er

s e e m s t o

be a l i t t le ,over,

T h e u s e o f o z o n e i s i n a d e q u a t e b e c a u s e o f i t s i n a b i l i t y t o c o n t r o l p l a n k t o n ,

T A B L E 2

:

C o m p a r i s o n o f f i l t e r r u n s w i t h C I 2 a n d C I O 2 p r e t r e a t m e n t .

I-~c~:DLOS TURBIDITY

TIHE WATERCH FTU

. . . .

O 5

2 . 5 1 0

6 12

2k ~4

48 75

7~ 120

2

5

I

8

2 9

6 2

8 9

0 . 2 0

O , 1 8

0 , 2 2 ~

0 1 8

0 . 1 9

_ m m l

O . 2 1

0 . 1 8

0 . 2 5

0 2 0

0 . 3 0

COAGU U~f f : ~ C ~O PPM - H 25Ob : 8 PPH

CL2 : 7 PPH - CLO2 : ~ PPH

FILTRAT IOH VELOCITY 5 H/H - SAND EFFECTIVE SIZE : O.95 t 4q

B~cter ic ida l and Vi~11ic lda l Effec ts

Although the main purpose of pro oxidation i s not the ~nac t iva t l on o f bac te r i a ,

g

i C d o e s h a v e s o m e a d v a n t a g e s a s a b a c t e r i c i d Q . [ t p r o v i d e s \ f o r a ' t o ~ g c o n t a c t t i m e ,

m a k e s p o s s i b l e a c o m p l e t e k i l l (i f S u f f i c i e n t r e s l d ua l i . . . . . . -:s p r e s e n t ) a n d m a k e s d i s i n -

f e c t i o n more re l i abl e. Table 3 in di cat es t however~ that ~uf fl ci en t conta ct t ime

• ¢

w o u l d e x i s t e v e n i f t h e se r e a g e n t s w e r e a p p l l e d . t o w a r d t h e ' e nd o f . t h e . tr e at m en t

process . I t a lso seems i l log ica l to t ry to k i l l bac te r i~ and v i ruse s in the pre l i -

mlnary stages of the process where they ar es ti l l prot ecte d b~ suspended so li ds ,

A p a r t i c u l a r e f f e c t o f a p r e t r e a t m e n t w i t h C I 2 o r C l O 2 i s t h a~ . .i t s t a b i l i z e s

the evolu t ion of the s lu J~ re t a in ed in the c la r l f le r , i In s ta t ic c la r i f ie r s where

t h e s l u d g e c a n be r e t a i n e d f o r s ev e r a l d ~ y s , t h e e l i m i n a t i o n o f p r e o x i d a t i o n w i t h

C l 2 or C 1 0 2 m a y a t i m u l a t ~ o b n o x ~ o u s ~ f e ~ n e n t a t i o n s , r e s u l t l n g i n t a s t e a n d o d o r s

o r s e d i m e n t a t i o n d i s t u r b a n ce s ,


8/17

~

BACTER I

ClDAL

_ . .

V I R U L I -

CIDAL

TABI,E 3

Disinfec t ion prac t ica l condi tions.

CL

O, - 0 .2 PPM

IO TO I5 MN

O.~ - O.5 PPH

30 TO ~5 I,,t,I

- _ . • ,

CLO

=O,.1 - O ,2 PPM

5 TO IOMN

o.3 - 0 .5 PPH

30

FREE RE~;

[

DUAL CCIqCENTRAT CNS

0 3

0.1 - 0.2 PPM

1 TO 2 bin

0.4 PPH

An~a~ja

Removal

¢ " • t •

II

-

C~ lo r in e b reaks down a=m on~a and~ [ o rm s ch [ o ra m t ne s ( b re ak -p oz n t t heo ry , ) .

• 3

S ,

~ oe t wo o t h e r s o x { d a n c s , c h l o r i n e d~ox[de and ozone, are i n e f f e c t i v e , A n ~ o n ~

can a~*o be removed

biologically, bu~ when the water

temperature

drops

below 5~;,

this ~turaL nitri£1cation deereasoa ~rastlcally and the use of chlorlne may st~\t~

be nece~ ary. 1 ¢ c o u l d , however, be u~ed la te r in the treatment process af te r

clari£ic.ation or even activated carbon filtration), when most by-products ~yecur-

t

sots

hav~

been removed.

Reac tion uith Organic Hat ter

Table 4 summarizes

t h e

var£ous e£fects o£ the ~hree oxidants on organic matter,

in addition to other pollutants. As a general rule, chlorine dioxide and ozone

are more efficient than chlorine in removing taste, odors and color.

TABLE 4

Su==ary o£ the main e££ects of the various oxidants.

POLLUTANT .

AMMONIA

ORGANIC

M TTER

TASTE

COLOR

THM '..FP

INCREASED

BIODEGRADAB| LI T~

CHLORINE

DIOXIDE

+ +4-

i ~ ; O

4" ++

-H.

+ 4-

O-sLOe NE

1

OZONE

++-b

O


9/17

253

. I f ; howeve r , o rg an lc , mac te r I s exp ressed as COT o r even COD, t im in f l ue nc e o f p re -

oxidation on its concentration remains very smuli. The'decrease due to chlorine or

chlorine dioxide pretreatment is general ly lone than I0%, Ozone may have a greater

x

~l ue nc e. This organic matter removal may take place through str ipp ing or enhanced

biodpgradatlon, but probably not through di re ct des truc tio n.

\ ~

The~maJor problem created by thc. react lon-- cl, ox| dsn ts with organic matter is the

formatio~ of by-products,

\ . . \

Chtorine reacts vith organiccoml~ounds and forms organol~aLogons. O£ these~ tri-

halomethanes (TllH~\are the most notorious and are the cause o~ the current contro~

versy over chlorine ~ee. Halomethanes, however, ere formed only when organic

precursors and free chlorxne residual are b£th present [or

a

~uff ic ienc contac t

t i~rT. Re du e- /~ e throe factors may In many. cases be a sa t l sf ac to ry measure.

Once formed, however, halomethanes are virtually impossible to ellmlnace by sub-

sequent

t r e a t m e n t s .

Chlorin e dio xide is a stro nge r oxi dant and does noC seem to form chl or in at ed

by-products.-Figure 7 confirms what is already widely accep ted : Cl0 2 does noC

produce TIiH, This,.Of course, is t rue when chlorine dioxide is correctly prepared

and is not accompanied by an important chlorine residual.

I / \ w,__ . ,m,~om~.o____~. • , ^ ¢

J f - / - \ S /

s ( ' i / ~ ~

. o

1~ zo / ~i l _

_ =_

/ ~ I ; ~ ~ - .,.Jql4

.~ _ ~ - = . : n

- - 1 5 .

, i

- - ' - . - - u

. . tu d II ~ I ~ ,,o, wn,out

. ]

n - - - . ; . . -

I PR[CNLORINATION3 J / I m, e~ ~ U w , , ' . , , ~- , , -u ~-~

._~_~

. . . - -

ALONE Pl t lCES$ (LINE 2 ] AT MOP.SIN& ( tO7S- t i l l

] ,

-- -. * "ALONli PROCESS WITH CI 0 z PRETR EATME N

'AT Vl l i l I |UX [11 |0 )

Fig. 7. Changes in chl'oroform con cen tr ati on along tre atme nt process.


10/17

2 ~ 4

It has been shown (9. II ) , however, that when chlo rine di oxide iu pres ent, ch lo ri ne 's

tendency to form T I IH is ' somewhat reduced. I t is thus gener all y accepted that ch lori ne

dioxide gsnera tes fewsr carc inogenic by-products than chlo r ine ,

Chlorites. As Jar as we kno~ at present, chloritea CCL02 ) are the chloriue

dioxide by-produ cts of maj or concern. Recent studies (2) have suggested that thes~

inorganic reaction products may present a higher risk o£ acute toxicity than chlorine

r o z o n e .

Upon oxida tion with ozone, ch lo ri te s form chl ora tes (I ) . Tim a£ fi ni ty o£ ClO 2-

for ozone is such that no ozone resi dual can ix is t tog eth er with chl or i t e (Fig ure S).

ChLorine d ioxide const i tu tes an in te rmedia te rea c t io n product be tween chl or i tes and

chl ora tes . When i t t~ used, the i ncreas e in ozone consumption due to the pres ence .of

chlorites may thus be consid erable (Figure 9). ~)e effect of chlorates on health is

st i l l very unce rta in, and i t seems pr efe rab le to keep the ~ at the lowest possible ,

l eve l .

o i

0,4

Q3

0 1

; R I l . , i v l l | L i d . a t

m i l l

~ ~ N¢ :lo s / t

\ , / °

o 6 o a

p M : ?

e l0 I - ia i t i I -~

0 4 B

~ 1 1

O l l * l I p h l l s | / I

~[g. 8. Changes in C102 and CI02~ r~idtt als whe n ozone is applied.

O z o n a t lo n i s n ot t h e o n l y t r e a t m e n t ~ t h a t i n t e r f e r e s w i t h c h l o r i t e s i n t h e t r e a t -

m e n t

pro ces s. Acti vate d Carbon decompd~es them. I t: 6a s. al ~o . 6een sugges ted, but

never proven~ that when chlo rites are presentt chlorine d ioxide may reform in the

pre sence o f f r ee ch lo r ine , -

Thus, the presence of chl o~ ' te 's ~n pr et re at ed '~ at e r has a atrong'I n£Xu, nee on ,

the desig n of the overal l t reatment process.


11/17

: I

I 2 ) 4

O I O N[ O O SE APN. I EO - PF M

F i g . 9 . O a o n e d e , m a d v i t h ( 4 ) a n d w i t h o u t - ( 4 t ) O l d 2 p r e t r e a t m e n t r t t V i g n e u x .

2 5 6

T a b l e 5 s ho w s t ho c h a n ge s in c h l o r i n e d i o x i d e an d i t s . i n o r g a n i c b y - p r o d u c t s a l o n g .

t h e t r e a t m e n t l i n e w i t h ClO 2 p r e t r e a t m c n t a t V i gn e u x , C h l o r a ~ i n e c o n c e n t r a t i o n .

( p r o d u c e d b y . e x c e s s c h l o r i n e r e s i d u a l ) i s p r e t t y s t a b l e ; C lO 2 a n d m o re p a r t i c u -

l a r l y C l 0 2 - d i s a p p e a r upon o z o n a t i o n , T h ey a r e moat p r o b a b l y t r a n s f o r m e d . i n t o V -

chloc tes ( l ) w h i c h a r e not e l i m i n a t e d b y C~C f i l t r a t i o n a nd t h e r e f o r a ' r e m a i n i n

t h e t r e a t e d w a t e r . S am p li ng p o i n t 6B i n d i c a t e s t h a t w i t h o u t , o z o n a t i o n c h l o r i t e s

a r e s t imf c tor i ly r e m o v e d b y GAC a n d a r e t h u s n o t t r s f i s £ o r ~ e d i n t o c h l o r a t e s .

u po n f i n a l o z o n a t i o n .

_ m

S N 4 P L I N G I

POINT

ii

TPEA'I'MENT

CL 2

CLO2

CLO2 -

0 3

3

l

0 . 1 0 0 . 0 0 0 . 0

0

1 0 6

0 8 8 0 8 4

o' O .S7

0 . 3 4 0 . 3 O

0 . 0 3 2 . ~ 2 .S ~ ~ . ~ 0

o o o 5 . 2 5

5A 5B 6

i i

O . O 4 0

O.11 0

0 . 0 0 O ,

0.~6- 0

6 8

O

O

•

0 . 0 3 -

O

TABLE 5

Oxidant c o n c e n t r a t i o n

a l o ~ t he V i g n e u x t r e a t m e n t

p r o c e s s , a f t e r C I 0 2

p r c t r e a t m e n t

dULY ]O 1980 : k K . : ~O PPH

CL02 : h . t~ PPH

' O ] I : 2 PPPt

I I : 0 , 7 P PH

I n o r d e r t o k e ep in o r g a n i c b y - p r o d u c t s . t o a ~ o /~ u m l e v e l o z o n a t i o n s h o u l d b e

c a r r i e d o u t a f t e r CAC f i l t r a t i o n . T h i s , a s ~ e s h~ 11 s e e l a t e r ~ p r e s e n t s s o ~ e

d i s a d v a n t a g e s a n d r e p r e s e n t s a n a d d i t i o n a l r e a s ~ f o r n o t u s i n g CIO 2 a s a p r e t r e a t -

mea t

O z o n a t i o n r e a c t i o n p r o d u c t s a r e s t i l l r e l a t i v e l y u n kn o un . E po xy b y - p r o d u c t s h av e

been s u g g e s e e d b u t n o c l e a r ident i f lc e ion of t~Lm has been made. Host o z o n a t l o n


12/17

P56

rea ct i on prod ucts hav~ ac id ic , ketones and a ldehyde groups and are thus prob ably

more blodegradablo. Ozone does not produce hslogenated compotmds, but in some cases

m y incre se the concentr tion in trih lometh no precursors T]LH FP). This is indi-

cated in f igure 7 , ~here ozonacion of prechlorlnated water increases the concentration

In

l l l M .

INTERMEDIATE OXIDATION

We saw (Figure I ) th at oxi dat ion could a lso be appl ied in the Middle of the t rea t-

mea t p roce ss , a f t e r c Ja r i f l c a t l o~ and be fo re sand o r GAC f i l t r a t i on . Ch lo r ine and

c h l o r i n e d i o x i d e in tha t p o i t i o n vould s t i l l p r e s e n t most ot the d i sadvan tages

ment ioned above. Ozone , on the o the r hand ( l l )~ p resen t s in te res t ing cha rac t e r i s t i c s .

I t c o n t r i b u t e s t o t he e l l m i ~ a t l o n o f a d d l t l o n a l o r g a n i c s and t h e r e f o r e d e c r e a s e s t h e

load appl ie d to the GAC fi lt er s. This removal ~ay be ver y small in terms of TOC. At

Morsang i t i s on ' the o rde r o f 5 Z . Ozone by-pr oduc t s can be ' e l im ina t ed th rough adsor -

p t io n , and i f the raw wate r con ta ins hu~ ic ~a te r la l s , th rough b iode grada t ion as ye l l .

Both can take place in the GAC f i l te rs and have con tr i but ed to the success of the

sequence

o z o n a t i o n

OAC filtratio~.

There is ~uch controversy over the pos si ble enhancement of b io deg rad at i on by GAC

(Bio lo g ica l Ac t iv a ted Carbon) . Severa l au thors (6) now be l i eve tha t the same b inds -

g rada t ion cou ld be obse rved in f i l t rn t ion on non-a dsor p t iv e mate r i a l s . The amount o f

TOC removed th rough such b iod egra da t l on (pa r t i c u la r ly i f the absence of p rech lo r l -

na t ion has l e f t room fo r p rev iou s b iod egra da t i on in the c la r l f i c ~ and f i l t e r s ) r emains

small inm os t cas es , Resea rcher s (b) have thus t r i ed t~ ~evelop new org ani c measure-

ments , more acc ura te than TOC, to eval uat e th i s Assim ilab le Organic Carbon .

An add i t lona l advantage of ozona t ion i s tha t , even in th i s p o s l t i o n , i t e f f e e t l v e l y

i n a c t i v a t e s v i r u s e s . I f o x i d a t i v e p r e t r e a c m e n t i s ab an do ne d, t h i s o z o n a t i o n f u r t h e r

ensures d i s in fe c t io n . I t ha9 a l so been shown (4) tha t t h i s s t ro ng ox ida t ion s tep wi l l

reduce

t h e

f in a l d i s i n fe c tan t demand and ~ake the wa te r bore s t a b le .

ln t e r~e d ia t e ozona t io n thus appears to be no t mere ly an a l t e rna t ive to ch lo r ina t ion .

b u t a v e ry s p e c i f i c a nd o o m p l e m e n t a r y o x l d a t l o n t r e a t m e n t .

FINAL DISINF£CTION

Germic ida l Ef fec t iveness

A f ina l ge rmi c ida l t r ea tment has to be app l led to the wa te r be fo re ~ t l eaves the

p lan t . Th i s t r ea tment canno t p reven t acc i den t a l p o l I u t lo n in the ne twork , but does

p r e v e n t i t s d i s s e m i n a t i o n . A s~a~11 d l s i u f e e t a n t r e s i d u a l a l s o c o n s t i t u t e s a n e a s i l y

measurab le guaran tee o f the po t ab i l i ty o f the wa te r , o

I f bo th bac t e r ic ida l and v l r u l i c ida l t r ea tment have to be ca r r i ed ou t ac th i s

f ina l s t a ge , su f f l c ie u t con t ac t t ime mus t be p rov i ded( r ough l y one hour wl th s to le -

r a b l e r e s i d u a l conce n tra t ion - see Table 3) before the water leaves the plant . ThJ~

n e c e s s i t a t e s t h e c o n s t r u c t i o n o f r e s e r ~ o i Ys .


13/17

257

~ . t n b i l i _ t y

F L n n l d i s i n f e c t a n t h a s , t o b e q u i t e s ~ a b l e . ? h i s e l i m i n a t e s o z o n e , w ; . . r ~ d u c ~ s

b l o d e g r a d ~ b l Q

m a t e r i a l s ,

s t i m u l a t l n 8 b l o l o z i c a l

a £ t e r g r o w t h i n

tlle dis tr, , ,~,

network.

C h l o r i , e ioxi e e e e m s to b e m o r e s t a b l e t h a n c l ~ l o r l n e - F i g u r e 1 - , b u t t h ~

d i s l n ~ e c t u n t d em a nd s o f b o t h . ( i E ' t h o p r e v i o u s t r e a t m e n t s w e re s i m i l a r t o c h o se a p -

pli ed at Vi~

0 3

i

0 2

F i g

n e u x o r H o r s a n g ) ' r e m a i n a t a v e r y r e a n o n a b l c l e ve l .

c t o

/ . . , ~ ~ C H LO R IN E lO X lO |O I $ 1 N F [ C T I O N

/ / . / * ' - : ~ - O , M I k N D ,)L P ,c .S S [B N ,Q U W A L ~ T t R O , t ,[

/ . / / X o i M , N , E X . E S S i O W , , . , O R , N E e X , O ,

TIME- HDUA

_ - - . . . _ . q - -

, 0 2 o i

lO. Final disi nfec tant demand Vlry Chatillon mar ch

1 9 8 0

MeaSurement

T h i s r a i s e s t h e p r o b l e m o f m e a s u r e m e n t , C h l o r l n e ' d i o x i d e a n d t h e v a r i o u s o x i d a n t s

: d

w h i c h 8 o w i ~h i t , a r e r a t h e r d i £ f i c u l ~ t o m e a s u r e w i t h p r e e l s l o n - ( 7 ) . T he c o m p a r i s o n

c h l o r i n e o n

o n e

h a n d w i t h o n t h e o th Q r, a c o m b i n a t i o n o f C l 0 2 , : c h l o r i t e s ,

q

~

c h l o r i n e

a ~ d c h l o r a ~ I n e s i s s o m e w h a t d i f f i c u l t . I t t h u s s e e m s m o r e p r a c t i c a l t o s p e a k i n t e r ms

o £ " e q u L va l e n t c h l o r in e " e x p r e s s e d £ n v o l ~ e ( dr op s) O f r e d u c i n s , a g e u t - ( m e t h o d ~ i t h

K I a n d s o d i u m t h i o s u l f a t e o r p h e n y l a r s l n e o x id e ), t h a n i n w e i s h t o f d l s i n f e c t a n t . T h e

d i £ f i c u l c y i n m e a s u r i n 8 C l O 2 r e s i d u a l w h e r e i t s c o n c e n t r a t i o n s h o u l d b e a ~ c c ur a te l y

c o n t r o l l e d i s s , n o t l c e s b l e d l s a d v a n c a g e o ~ this reagent.

T a s t e a n d O d o r ~

I t is c o m m o n l y a c c e p t e d t h a t c h l o r l n e d i o x i d e r e m o v e s t a s t e s a n d o d o r s m o r e

e f f i c i e nt l y t h an c h l o r i ~ e , : T h i s L s ~ n d e e d t r u e f o r p h Q n o l i C t a s t e s ,: C ~ i o ri f i e

d i o x £ d e , h o we v er , s e e m s i n c , ~ F a b l e o f r e m o v i n g e a r t h y . ( g e o s m l n o r M I B} t as t es .

T h i s i s s h u w n . i n l F i g u r e I I. In b o t h c a ~ e s d u e t o r e s ~ d u a l " d £ s i 6f e c t a n t , " . ' I s a pp e a r s

b e l o w 0 . I p p m .


14/17

258

/

i

| Z / o ,:H,.o,,,,.

3 / - • CHLORINEOIGXIOE

E,

0.1

O,Z 0,3 0,4

0. 0,

0,7 O,I

FREE RESIDUALDISINFECTANTN PPM 'EQUIVALENTCHLURINE

Fig. II. Comparison

o f

tastes

due

to chlorine and chlorine dioxide. Vigneux. m.~rch 1980

(TON a r e a v e r a g e s f o r a p a n e l ' o f , s l X p e r s o n s ) .

B e c a u s e t h e s t a b i l i t y o f t i e 2 i s s o m ew h a t g r e a t e r t h a n t h a t o f Cl 2 , t h e u s e o f a n

excess CIO 2 residual, in comparison with the same dosage of chlorine, may increase

a p p r e c i a b l y t l i e ~ e u s t ' 0 m e r s ' c o m p l a l n t s , ' F i g u r e 12 i l l u s t r a t e s t h i s s c h e m a t i c a l t y :

the area (and the number of customers) getting a ~Ibad-tasrlng~' uater is much larger

w l t h C lO 2 t h a n w i t h c h l o r i n e w h en d o s a g e s w i t h m o r e t h a n 0 , I pp m r e s l d u a l , a r e

~ p p l l c d .

/ZONE WITHOUTFREEF l E S I O U A L - - - - ~ ~ x * * .

j /~o TASTE ~ N I

]/ .l ,

' ZONE WITH EXCESSFREE ',

O 3 5 10 O 3 i 3|

CHLORINE CHLORINE DIOXIDE

F i g . 1 2 . T h e o r e t i c a l e v o l u t i o u 0£ E r ee r e s l d u a l d i s i n f e c t a n t i n t h e d i s t r i b u t i o n

s y s t e m . C o m p a ri s o n b e t w e en c h l o r l n e a nd c h l o r l n e d i o x i d e ,


15/17

1 5 9

Fig. 13. A summary of the advantages

of the three oxldan~s.

ADDITIONAl, ADVANTAGES AND b[SADVA.'~TAGES

Figure 13 sum~arlzes the various advantages of the three oxidants. Several othbr

but comparatively less importr.nt ~eatures o I ~ the three dis inf ec tan ts may he considered

as advantages or disadvantage~. r h , e re la t ive t n d e p o n d e n c o of chlorine dioxide germi-

cida l ef fe ct from pH changes is, i'or inst ance , very*o£ten present ed

s O a n

advantage.

~oo r

A l i l l n t i ld e a il C h i l l i

~, ,-. . ; . , , . . - . , . , , : . ~ . . , .~

, ~ ' ; t~ , / ' . / . , . :. ,

• G r _ o _ i ~n d ~ / _ a _ t _ e _ r

_Tr_eatment

OI sne O i o s , / i l e d e ch l ore

~ ~sclillss ~ Absnc. of T H M

V i f H . Q o i t s s t ¢ a . d l u f |

A u t f | | p | t h o g | a | # | | f i t , H a `

~ ' S l m l n | n c | @ N H 4 4

The example that has been presented of a rather sophisticated surface water treat-

menc process does not by any means repre sen t the best process for al i eases req uir ing

treatment by oxidation. In the case of ground waters, with a li tt le organic content

but wlth iron and more particularly manganese in high concezltration, it would ~e

preferable to use ozone esther than chlorlne or chiorlne dioxlde.

Water with phenolic tastes sh0~Id be ~reeted*with chlorine diozlde (or ozon0)~

hot not with chlorine.

~ost ground ra te rs with a low 0rganlc c ontent could, h~aever, be ~ere ly tre ate d

with a small chlorine dosage.

C ~ s c and Operati~na 'C6nslderations

Chlorine is ce rt ai nl y the most cmnxnonly used chemical in water tre atme nt, In i ts

llqulfied gas form. itrepresents a dangerous prod'uc't and stringent Safety requxre-

meritsare "needed for its storage and'handlln8'. I't can ai'so be Used in the~fomof

hypochlo rite's, vhich are much ea si er tO manipulate but r e su l ti n ~igher Co's~. Dosing

equipment for chlor ine is slmpler and ea sle r' to~ ope ra te .


16/17

2 6 0

C h l o r i n e d i o x i d e I s p r e p a r e d o n s i r e , t h r o u g h t he r e a c t i o n o f s o d i u ~ c h l o r i t e

w i t h c h l o r i n e g a s o r h y d r o c h l o r i c a c i d . I n t h e f o n a e r c a s e

the

s am e s t o r a g e p r o b l e m s

a r i s e a s w i t h c h l o r i n e but an e~e rg en c y c h l o r i n e g a s s u p p l y i s a v a i l a b l e i f t h e

d i o x i d e

g e n e r a t o r b r e a k s d o ~n . T h i s g e n e r a t o r

~ust

b e o p e r a t e d u n d e r a l m o s t s t o e -

c h l c ~ a e t r l c c o n d i t i o n s

to avoid

a n e x c e ~ s o f c h l o r i n ~ o r c h l o r i t e . T h i s i s g e n e r a ] I v

d i f f i c u l t t o a c h i e v e . C I0 2 g a s i s e x p l o s i v e a n d s a f e t y d e v i c e s m u st b e u s ed i n t h e

s t o r a g e o f C ]O2 c o n c e n t r a t e d s o l u t i o n s . T he r e a c t i o n o f c h l o r l t e ~ I t b c Q n c e n t r a te d

a c i d i s a l s o e x p l o s i v e a nd t h e s e c h e m i c a l s s h o u l d b e k e p t a p a r t . I n a d d i t i o n t o l o ~ e r

e f f i c i e n c y

u p

t o

9 0 ~ w i t h ~ e i d a n d 95 ~ ~ i t h C I 2) . t h e p r e p a r a t i o n v i t h h y d r o c h l o r l c

a c i d p r e s e n t s t h i s d i s a d v a n t a g e .

~ z o n e ~ o r ~ a t h e r o z o n a t e d

a i r

i s a l s o p r o d u c e d o n ~ i ~e b y p a s s i n g a ~ r y a i r f l o ~

b e t v e e n t~o e l e c t r o d e s

under

a p o t e n t i a l d [ f ~ e r e n c e o f

15 000

t o 2 0 , 0 0 0 v o l t s . T he

t o t a l e q u i p m en t C ai r p r e p a r a t i o n , o z o n e g e n e r a t o r , c o n t a c t ch a m b e rs ) r e p r e s e n t s s u b -

s t a n t l a l c a p i t a l a nd o p e r a t i o n a l c o ~ t s .

T a b l e 6 g i v e s a n e s t i m a t e ~ o r t h e P a r i s a r e a o f t h e ~ o ~ al c o s t s o p e r a t i o n a l +

c a p ~ t a l ) o f t h e d i f f e r e n t d i s i n f e c t i o n t r e a t m e n t s u s e d i n a f i n a l ~ t a g e . T h i s c o s t

gives a c l e a r a d v a n t a g e t o c h l o r i n a t i o n .

O. } O J

0.4 a ~ '

4 b I xO

r. r ,, no ~.p~,...I

TABLE 6

A v e r a g e c o s t s of c h l o r i n e , o z o n e

• a nd c h l o r i n e ioxi e t r e a t m e n t s .

COSCLOS10N

1 ) T h er e d o es n o t se em t o b e a d e £ 1 n i t e s u p e r i o r i t y o f oz o n e o r c h l o r i n e d i o x i d e

o v e r c h l o r i n e . P r c t r e a t ~ e n t ~ i t h a n o x i d a n t s h o u l d b e a v o i d e d a n d a l g a e g r o w th co u l d

b e c o n t r o l l e d m e c h a n i c a l l y b y c l e a n i n g a n d / o r c o v ~ r l n g t h e w o r ks .

i i ) C h l o r i n e s t i l l p r e s e n t s t h e a d v a n t a g e o f re m o v i n g a a ~o n ~ a a nd m i g h t b e i n so me

c a s e s a b s o l u t e l y n e c e s s a r y .

l i l ) O z on e f o l l o v e d b y GAC f i l t r a t i o n m ay ~ a v e a p o s i t i v e e f f e c t .

i v ) C h l o r i n e , a t d o s e s b e l o ~ 0 . 3 p p ~ m ay b e k e p t a s ~ f l n a l d l s l n f e c t a n t .

I n o r d e r t o r e d u c e c h l o r i n a t i o n b y - p r o d u c t s t o a m i nl m u~ l e v e l , t h e b e s t s o l u t i o n

i n t h e l o n g t e r m ~ i s t h e u s e o f G A C. l ~ n y p l a n t s , h o w e v e r , w i l l n o t b e a b l e t o

i n t r o d u c e t h i s t r e e , e a t £ o r s e v e r a l y e a r s . O z on e a n d C IO 2 m ay t h u s b e u s e d as a l t e r ~

n a t i v e s t o c h l o r i n e ~ b u t o n l y f o r a n i n t e r i m p e r i o d o f t i m e .


17/17

2 6

R E F E R E N C E S

I Y. Richard and L. Bran er, In te rf er en ce Dioxyde de Chlore - Ozone en Tra ite men t

d Eau de Consommation, Congr~s A,G.H.T.M., Str asb our g, oc tob re 1980

2 R.J. Bull , Health Effe cts of Alternat e Dis inf ecta nts and the ir Reaction Products,

J.A.N.N.A., 72 (may 1980), 299-303

3 F. Fies slng er, J. Hal lev lal le and A. All izadeh , Effect Floculant d~ l Ozone,

In ter na tlo nal Ozone In st i t ut e Conference, Nice, janv ier

1979

4 F. Fi ess lng er and A. Hon tlel , Case Studies for the Abandor~ent of Pr ech lo ri nat lo n,

A.N.N.A. Annual Conference, Atlanta, june |980

4b~s ¥. Richar d and P. Blue, O z o n e P r e t r e a t m e n t o f D r i n k i n g W a t e r I n t e r n a t i o n a l

O z o n e I n s t l t u c e Symposium, Los Angeles, may 1978

5 N. K~hn and H. Sonth elmer, Precede s d*Oxydation Appliques au Tra lte men t de l Ea u

P o t a b l e . K a r l s r u h e 78 Rarls ruhe 1979 p. 854

6 J. Van der Kooij, Processes during Bio logl cal Oxidation in Fi lt er s, garl sru he 7B,

(ref . 5) , p .

774

7 N . H a s s c h e l e i n P r o g r ~ s d e l a C h i m i e d u B i o x y d e d e C h l o r e G ~ n l e l n d u s t r l e ~nie

C h i m i q u e 9 7 I J a nv 1 9 6 7 4 9 -6 1 e t 9 7 -3 f e v . 1 9 6 7 3 4 6 - 3 5 4

8 C. Gomella e t P. Husqu~re, La VAs lnf ect ion par le Chlor e, l Ozone et le Vloxyde

de Chlore, 13e Congr~s A.I .D. E., Pa ri s, sept.

198

9 R . G. R i c e a n d J . A. C o t r u v o O z o n e / C h l o r i n e D i o x i d e O x i d a t i o n P r o d u c t s

of

O r g a n i c

H a t e r l a l s P r o ce e d in g s o f I O I

Conference, Nov. 1976,

p . 4 8 7

]0 Y . R i c h a r d a n d L . B r en e r D i s i n f e c t a n t s a n d E q u i p m e n t f o r D i s i n f e c t i o n I n t e r -

nat lonal Water Conservancy Exh ib i t i on Jonk~p tng sep t . 78

Y. Richard and F. Fi es si ng er , Emploi Compl~mentaire de l Ozone et du Charbon

Actif 1.0.1. Conferen ce Paris may 1977

12 C. ¥ap i j ak le, ICx for H20, Water and Wastes Engineer ing 15, may 1978, p. 33-37

s0048-9697(81)80062-9] F. Fiessinger; Y. Richard; A. Montiel; P. Musquere -- Advantages and...

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Transcript of s0048-9697(81)80062-9] F. Fiessinger; Y. Richard; A. Montiel; P. Musquere -- Advantages and...