the influence of the ozonation dosage on the structure and biodegradability of pollutants in water,...

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The Influence of the OzonationDosage on the Structure andBiodegradability of Pollutants inwater, and its Effect on ActivatedCarbon FiltrationRégis Brunet & Marie-Marguerite Bourbigot,a Université de Poitiers , Avenue du Recteur Pineau, 86000PoitiersPublished online: 23 Jul 2008.

To cite this article: Régis Brunet & Marie-Marguerite Bourbigot, (1982) The Influence of theOzonation Dosage on the Structure and Biodegradability of Pollutants in water, and its Effecton Activated Carbon Filtration, Ozone: Science & Engineering: The Journal of the InternationalOzone Association, 4:1, 15-32, DOI: 10.1080/01919518208550935

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OZONE: SCIENCE AND ENGINEERINGVol. A, pp. 15-32, 1982Pergamon Press Ltd.Printed in the USA.

0191-5912/82/010015-18J03.00/0International Ozone Association

Copyright (c) 1982

THE INFLUENCE OF THE OZONATION DOSAGE ON THE STRUCTUREAND BIODEGRADABILITY OF POLLUTANTS IN WATER, AND ITS

EFFECT ON ACTIVATED CARBON FILTRATION

1 2 1RSgis Brunet , Marie-Marguerite Bourbigot , Marcel DorS

Universite de Poitiers, Avenue du Recteur Pineau, 86000 Poitiers

2Compagnie Generale des Eaux, 52 rue d'Anjou, 75008 Paris

Abstract

Laboratory tests underline the improvement which ozonation bringsabout in the removal of organic micropollutants in surface water withactivated carbon filtration. Optimal ozone dosages correspond to thestabilization of the asymptotical diminution of UV absorption. HPLCanalysis shows that, though ozone sometimes degrades organic compoundsinto more polar and less adsorbable products, improvement in GAC fil-tration is attained through increased bacterial activity, as revealedby measurements of ATP, of dehydrogenase and of oxygen consumed.

Introduction

In surface water treatment, the clarification process is more and more oftenfollowed by a polishing stage, for which one now usually uses the combined actionof ozonation and granular activated carbon' filtration (1,2). But all the phenome-na which play a role in the combination of ozone with carbon filtration have notyet been mastered. The identification of the thousands of compounds present intrace amounts at this point in the treatment process would require analyticaltechniques which we do not have (3). This is a handicap in the study of the beha-vior of organics during the various treatment steps.

For aqueous solutions of pure products, ozone's mode of action organic matter andthe reaction processes are beginning to be understood, especially for aromaticcompounds (4,5,6).

In this study, we have not sought to identify organic compounds present in surfacewater throughout the treatment line, but have studied the evolution of some chemi-cal and biological parameters which are liable to add to an understanding of thephenomena.

To this end, we have studied the following parameters in a laboratory at Poitiers,in a pilot plant at Choisy-le-Roi, and full-scale at the treatment plant at Mery-sur-Oise:

- the evolution of aromaticity as a function of ozonation dosesj

- the evolution of TOC according to treatment;

- the evolution of the polarity of compounds analyzed by HPLC;

- the evolution of bacterial activity within activated carbon filters or after theinoculation of samples of water ozonized at various doses.

Experimental Results

In the laboratory (the experimental ozonation apparatus used is represented sche-matically in Fig. 1), the ozonized air is introduced at the base of the contactcolumn where water flows countercurrently. Water is retained in the column forfour minutes, residual ozone is then removed by magnetic agitation.

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16 R. Brunet et a l .

Pump

ozonizedwater

filtered Seinewater

Fig. 1

Schematic diagram of the donation pilot :

Reactor diameter : 6 cm, Capacity : 2,351, Column height : 120 cm

The setup of the pilot plant is shown in Fig. 2. Two treatment lines were tested:

- line 1, where carbon filtration is placed downstream of the ozonation;

- line 2, where carbon filtration precedes ozonation.

The activated carbon used in both cases is a Picactif. The filter rate is 5 m/hfor a layer one meter deep.

The drinking water treatment plant in this study is mery-sur-Oise. A polishingfiltration through activated carbon preceded by an ozonation was placed in servi-ce in this plant on August 1, 1980. The treatment process is outlined in Fig. 3.

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Influence of Ozonation on Pollutants 17

ozone at variablerate

EBEBPED,

EO,

EFEFEO

1222'22

River Water (Seine)preozonized raw water

Settled waterFiltered sand waterOzonized water

Filtered carbon water

Postozonized water

O,R.V. Ozonation to obtain avirucidal residual

UJiEO,

Fig. 2Experimental scheme of pilot plant

0,R.V.

Storage First(400x10'm) Ozonation Qise River

Treated water

Post-IfU Sedimentation Sand Second Activated ChlorinationB Filtration Ozonation Carbon

Flocculation . Filtration

Fig. 3

Treatment process at Mery-sur-Oise

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18 R. Brunet et al.

Evolution of UV absorption as a function of ozonation dosage

Measurements taken at two wavelengths show a diminution in absorption in relationto ozone doses. Organic compounds which absorb at these wavelengths are partlyoxidized. The ozone dose to be applied to obtain minimal absorption is closelyrelated to water quality, as shown in Figures 4, 5 and 6, obtained with water fromvarious origin.

1 0-D.

X - 254 rim

Fig. 4 : Seine water

o i 2 3 *

Fig. 5 : Oise water

Reduction in concentration of the U.V. absorbing substances contained in a clarified water as a functionof the ozone dosage (laboratory test)

0.05

OJM

0X13

0.02

OJ>1

0.0 . 254 nm

D^ I T — •

•

»f!er donation •

•ftw GAC filtration Q

ozona dos«

'•0 2.0

Fig. 6 a

Reduction in concentration of the U.V. - absorbing substances contained in a clarified Oise water as a function

of the ozone dosage (test performed in Mery / Oise plant)

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0 1 oa 0.3 0.4 0.B 0.6 0.7 0.8 O.i 1 1.1

Fig. 6 bduction in concentration of the U.V. - absorbing substances contained in a clarified Oise water as a function

of the ozone residual after ozonation treatment (test performed in Mery-sur-Oise plant)

O.D. 264 n

Influence of Ozonation on Pollutants

•ftsr ozoiuuion •

• t in GAC filuation t l

19

Ozona mitJui!ms/L

Evolution of total organic carbon

In the laboratory and in the pilot plant, we noted in the samples studied thatthe TOC is relatively stable in the conditions of ozonation which might exist indrinking water treatment. The observed loss is most often between 5 and 15 % (Fi-gure 7 and 8), and in some cases, no reduction was noted.

A T - ° - c -(mg/L)

4 .3 <••

4.1

3.9ozone dose 2 0

(mg/L)

0 1 2 3

Fig. 7Variation of T.O.C. contained in a clarifiedSeine water as a function of ozone dosage

2.4

2.2

2.0

T.O.C.(mg/L)

-

5 .O

1

o

o

t

ozone dose(mg/L)

1

Ffn ft

Variation of T.O.C. contained in a clarified Oise

water as a function of ozone dosage

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In the pilot plant at Choisy-le-Roi, TOC removal in the carbon filter is fairlyconstant, between 20 and 25 % no matter the ozone dosage applied upstream. Anozone dose between 1 and 2 mg/1 nevertheless seems to favor TOC abatement in thefilter (Fig. 9) but the differences are hardly significant.

35

30

20

10 _

% T.O.C. removed

-o a

0.5 1.5ozone dosage(mg/L)

Fig. 9

Removal efficiency of T.O.C. from activated carbon filter a and frompreozonation +. activated carbon filter b as a function of ozone dosage

Evolution of polarity of organics as analyzed by high-pressure liquidchromatography

The global evolution of non-polar and slightly polar organic compounds duringozonation can be shown by HPLC, after concentration of the sample by direct pum-ping on the column (silica coated with chemically-bonded octadecyl groups (Cis))followed by elution by programming of solvents water/acetronitrile (Waters solventprogrammer and pumps). Detection of compounds, eluted in the order of their decra-sing polarity, is effected with ultraviolet at 220 ran (Lirec SP 907 spectrophoto-• meter).

In Fig. 10 are shown the chromatograms obtained on a sample of filtered Seinewater, ozonized in the laboratory at doses from O to 1.75 mg/1. The chromatogramsdrawn with dotted lines were obtained after inoculation of these samples withmicroorganisms (conditioned activated sludges; suspended matter: 30 mg/1) duringa contact time of 90 hours.

On the non-inoculated samples, a reduction of UV absorption is observed with res-pect to the ozone dosage for the majority of the organic compounds which can beanalyzed in these conditions. From an ozone dose equal to 1.3 mg/1 onwards, thenon polar and slightly polar compounds are oxidized for the most part.

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Solvent

(min) 40

Fig. 10 aHPLC Profile of clarified Seine water as a function of ozone dosage

(* samples inoculated with microorganisms)

Solvent

Ozone dose of 0.65 mg/L

xO,64

elution time

(min) 40 30 20 10

Fig. 10 b

HPLC Profile of clarified Seine water as a function of ozone dosage


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22 R. Brunet et al.

x0.64

(min) 40 30 20 10

Fig. 10 c



I Solvent

Ozone dose of 1.1 mg/L

(min) 40 1020

Fig. 10 d



xO.64

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Influence of Ozonation on Pollutants

(min) 40 30 20 10

Fig. 10 eHPLC Profile of clarified Seine water as a function of ozone dosage

Ozone dose of 1.75 rng/L

elution time

xO.64

(min) 40 30 1020

Fig. 10 f


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24 R. Brunet et al.

After 90 hours of contact with microorganisms, ozonized samples present lessabsorption, resulting from the biodegradation of certain compounds; this biode-gradation is much less manifest when water is not ozonized.

Evolution of biomass activity in clarified surface water as a function of ozonedosage

In order to determine the optimal ozone dosage to obtain a thorough biodegradationof organic products, and to avoid a treatment dose which may eventually involveinhibition of bacterial activity, we studied, in the laboratory, the incidence ofozonation on the activity of microorganisms introduced into different samples ofwater.

Four methods were implemented in parallel:

Determination_of" ATP_for high inoculation_dqses

Inoculation is done with activated sludge, washed by dilution in distilled waterand concentrated by centrifugalizing, so as to remove to the maximum substratebound to microorganisms. These microorganisms are brought into contact with eachsample, in a closed medium and at 20°C, at a rate of suspended matter equal to30 mg/1. ATP is determined in each sample after an incubation time from 70 to 90hours. Microorganisms are retained by filtration through a 0,22 fi membrane andplaced in boiling TRIS buffer to extract ATP, determined by the reaction of bio-luminescence (Lumacounter M 2080).

Determination of ATP for low_inoculation doses

Measurement is undertaken, in a closed medium, by the introduction of a smallamount of bacteria into each sample. Inoculation can be effected by bacteriataken from carbon grains or by dilution of activated sludge or with the micro- ,organisms present in non-ozonized filtered water. The samples to be inoculatedundergo sterilization by membrane filtration beforehand. The results given werearrived at by carrying out inoculation with an identical volume of filtered water ifor each sample, on the order of 5 % of the total volume of sample (7).

After different incubation times at 20°C, ATP is determined by direct extractionon 1OO pi of homogenized sample.

Determination of activity of_dehydrogenase^_forJiigh^inoculation_doses^

Under the action of dehydrogenase, TTC (2,3,5 triphenyltetrazolium chloride) usedas oxydo-reduction indicator, can be reduced to TTF (triphenylformazon chloride),a red product, soluble in organic solvents. The amount of TF formed, proportionalto the concentration in dehydrogenase, is representative of the activity of microorganisms.

The inoculation procedure and the incubation time are the same as those describedabove, TTC being introduced into the samples. After incubation at 20°C, micro-organisms and TF are retained by membrane filtration, the TF is extracted withisoamylic alcohol and determined by spectrophotometry at 485 nm.

Respirometric measurement for high_inoculation doses

Determination of the oxygen consumption proportional to the activity of micro-organisms is effected by measurements of dissolved oxygen (galvanic probe/Ponsel-le 02 TLE). Incubation is carried out in a closed medium, at 20°C, after inocu-lation with conditioned activated sludge.

The biomass activity as obtained with the last three techniques is shown inFig. 11. The sample considered was taken at the Mery-sur-Oise plant after sandfiltration.

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Evolution is similar for ATP determination and measurement of dehydrogenase:marked by a stability in activity for ozone doses under 1.5 mg/1, followed by aprogressive increase, which stabilizes at 2.5 to 3 mg/1 depending on the techni-que employed.

It may be noted that an incubation time of 24 hours does not appear to be suffi-cient for adaptation of procedure (2nd procedure), and that the measurements ofoxygen consumed indicate a less pronounced evolution.

0,25

0.20

0.15

/\

0.10

0.05

, A.T.P.(ng/cm3)

-

-

t = incubation time

t 2 = 70 hr

tj = 24 hr

ozone dose(mg/L)1 M

1 2 3

Fig. 11 a

Influence of ozone dosage on the biomass activity as estimated

by A.T.P. measurement (Assay b)

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26 R. Brunet e t a l .

% Oxygen consumption

Fig. 11 cInfluence of ozone dosage on the biomass activity as estimated

by oxygen consumption (Assay d)

80

60

40

20

0 (

Activity(with TTC)

•

•

/ t = 70 hours

/

/r

\j£.\J\VS DUK

(mg/L)

1 2 3

Fig. 11 b

Influence of ozone dosage on the biomass activity as estimated

by dehydrogenase measurement (Assay C)

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Evolution of biomass activity in an activated carbon filter as a function ofozone dose applied upstream

Measurements of activity were carried out in the activated carbon filters of thepilot unit at Choisy-le-Roi. The values lie between 300 and 2O0O ng of ATP/g ofmedia (bacteria are removed from carbon grains by ultrasound passage). Valuesabove 1000 ng of ATP/g of carbon were obtained for both line in June and July.In Fig. 12 are shown the relationship between the activity of line 1 (O3 + GAC)and the activity of line 2 (GAC + O3) with reference to the ozone dosage appliedin line 1.

The two carbons working in parallel, computation of this relationship allows toeliminate the influence of external parameters (temperature, variations in rawwater quality ...) . A maximum is obtained at an ozone dose of 1 mg/1 for samplestaken at two depths of filter media, 1/3 and 2/3.

Fig. 12Influence of ozone dosage on the biomass activity in the GAC filter

(Test performed in the pilot plant)

Evaluation of the effectiveness of carbon filters in the removal of biodegradableorganic compounds by ATP degradation

The three samples considered are from the Mery-sur-Oise plant. They are takenbefore and after filtration through two types of granular activated carbon. Theozone dose applied before filtration is about 1.7 mg/1. The samples are stereli-zed by membrane filtration (0.22 fi) and inoculated with a quantity of sand-fil-itered water following the second procedure outlined above.

After 72 hours of incubation at 20°C, ATP determination reveals a reduction inactivity after activated carbon filtration:

ozonized water

water filtered throughNORIT ROW O.8 Supra

water filtered throughCHEMVIRON Fs 300

628 ng of ATP per liter



Such an evolution has already been observed by other authors (18).

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Discussion of the results

Asymptotic reduction of UV absorption curves at 254 nm and 270 nm shows thatozone readily oxidizes the aromatic compounds chiefly responsible for absorptionat these wavelengths, as well as unsaturated aliphatic compounds. The maximumobserved removal, between 50 and 60%, is obtained for ozonation doses between 1and 3 mg/1, depending on the nature of the water considered. Greater abatementshave already been demonstrated for surface waters (8), but at higher ozone doses.Studies carried out on aqueous solutions of pure products show that as a generalrule, aromatic compounds (4,6,9,10,11,12,14) and unsaturated aliphatic compoundsrapidly degrade into products which are more polar, of small polar mass and rela-tively stable with regard to ozone. Nevertheless, with respect to aromatic com-pounds, the nature and the position of substituents in the ring will determinethe extent of oxidation and the nature of the obtained products.

The reduction in TOC obtained through oxidation remains limited, most often from5 to 15%. In some cases, for lightly-loaded samples (TOC = 2 mg/1), a stabilityof this parameter in the ozonation conditions cited was observed. This relativestability can be interpreted by the oxidation of unsaturated compounds into moreoxygenated products of lesser polar mass such as alcohols, aldehydes and ketones(16,17). To be transformed into C02 these compounds would require higher dosesand contact times much longer than could be applied in drinking water treatmentplants.

TOC abatement obtained in activated carbon filters which have been in operationfor over a year without regeneration is on the order of 20 to 30% whether filtra-tion be preceded by ozonation or not.

Results obtained with HPLC show a disappearance of certain polar and slightlypolar compounds after ozonation. This has already been observed during previousresearch which showed the appearance of or the increase in polar compounds (19).This polarization of organic matter will entail a diminution in its adsorbabilityin the activated carbon.

Now the same TOC reduction was noted during studies carried out in the pilot plantat Choisy-le-Roi for ozone doses varying from 0 to 2 mg/1. Phenomena other thanphysical adsorption must therefore be responsible for a part of this removal.Biosorption and then biodegradation phenomena play a role. These mechanisms havebeen demonstrated in the laboratory (20), and their action becomes greater asozone doses are increased.

The measurements of biological activity presented in this study well show theincrease in biodegradability as a function of ozonation dosages. In the sample ofclarified water from Mery-sur-Oise, the total biodegradability increases at ozo-nation doses above 1 mg/1 and stabilizes at ozone doses from 2 to 3 mg/1 (Fig. 11).

In many samples of clarified water from the pilot at Choisy-le-Roi, with the pro-cedures outlined above, maximum activity of microorganisms is obtained at treat-ment doses around 1 mg/1, which is confirmed by measurements of biological activi-ty in the activated carbon filters (Fig. 12). Comparison with HPLC of inoculatedand non-inoculated waters also show ozonation's increase in the biodegradabilityof organic compounds (Fig. 10).

Further, measurements of biological activity effected by ATP determination bydirect extraction on a sample of water from the Mery-sur-Oise plant ozonized at1.7 mg/1 indicate that after activated carbon filtration at a 2 m/h rate, theamount of assimilable organic carbon decreased.

Nevertheless, TOC abatement remains, in these operating conditions, limited to20-30% during activated carbon filtration. To obtain a substantially higher remo-val, a regeneration would be needed about every 1OO days for a filter rate of 2to 3 m/h. This is not actually done in large-capacity treatment plants, and it ishard to imagine how it could be.

The effectiveness of the coupling ozonation + activated carbon is no doubt limitedby three phenomena:

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stability to ozonation of organic adsorbable and non-biodegradable compounds;

inadequate contact times (excessives rates) or inadequate carbon layer;

- insufficient load of organic biodegradable compounds to ensure adequate deve-lopment of zooglea which does not allow the biosorption process to begin. Giventhe short contact times in the filters, retention of biodegradable products inthe carbon pores is necessary to bring about the formation of zooglea in whichthe biosorption phenomena^ will take place.

But in spite of this still limited efficacy, the coupling ozonation + activatedcarbon filtration is used more and more widely for treatment of waters loadedwith organics, for it is the only process by which the content in nutrients forbacteria in distribution systems can be limited in economically acceptable con-ditions.

At this point of understanding, a number of means to improve the effectiveness ofthe coupling ozone + GAC with regard to TOC elimination are feasible:

- by turning to oxidation phenomena, the use of combined oxidation process canbe considered;

- by turning to the phenomena of adsorption and biodegradation, by favoring forexample a sizeable zooglea development through an eventual spiking with a bio-degradable product with a certain adsorbability in carbon.

In this respect may be mentioned laboratory experiments with carbon filters fedwith clarified surface water (TOC = 2 to 2.5 mg/1) and enriched with phenol solu-tion ozonized up to a disappearance of 90% of the phenol (influent TOC — 6 mg/1)which resulted in:

- high inoculation rates (10 times higher than those observed in a filter fedwith non-spiked water);

- TOC abatement on the order of 80% (TOC OL 1 mg/1);

- or finally by focusing on the contact time. Its influence as well as that ofthe media have been demonstrated by comparison with four filters running inparallel. Results, displayed in Table I, show carbon's superiority over sandand calcined clay.

TABLE IComparison of the efficiency of various filters after ozonation

CarbonV = 2 ra/ht =30 mn

Calcined Clay

V = 2 m/ht = 30 mn

Vt

Sand

= O.2 m/h= 5 hrs

DualsandV =t =

media+ carbon0.2 m/h5 hrs

carbon depth 0.2m

TOC abatementmg/1

% TOC eliminated

chlorine consump-tion in 72 hrsdosage =1.5 mg/1

0.2

1.4

0.3

12

1.2

0.8

32

O.5

0.6

24

0.8

Depth of filter media = 1 meter; water ozonized at 1.3 mg/1; TOC =2.5 mg/1;average of 20 measurements obtained over two months after a start-up period of3 1/2 months.

The carbon in the dual media filter was taken from the carbon filter after the3 1/2 month start-up period.

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Bacterial enumerations, performed at different levels in the dual media and theactivated carbon filters, show that the total flora, represented essentially bygram-negative rod bacteria, is on the order of lO6 bacteria per gram of carbon inboth filters, while it is equal 3 x 1O4 bacteria per gram of sand in the dual-media filter.

Carbon is therefore the best adapted medium for TOC removal, which entails redu-ced chlorine consumption and ensures higher distributed water quality (2). Thenature of the activated carbon does not appear to have much influence, so whatare sought are the least burdensome carbons allowing long contact times in econo-mically acceptable conditions.

The contact time is indeed an important factor since in the dual-media filterwith a depth of O.2 m and a contact time of 1 hour, TOC abatement is clearlygreater than that obtained with 1 m of carbon and a contact time of 30 minutes.This difference can probably be attributed to the biological phenomena whichrequire longer contact times than the physical adsorption phenomena.

Conclusion

The results presented show that ozonation oxidizes aromatic cmopounds, which isdemonstrated by a reduction of UV absorption at 270 and 254 nm; the ozone dosageleading to minimal absorption depends on the quality of the water treated, and ingeneral a plateau corresponding to an abatement of optical density on the orderof 50% is reached.

HPLC analysis reveals also an increase in polarity of dissolved organic matter,as a fuction of the ozonation dosage, which results in an increase in biodegra-dability, evindenced by measurements of bacterial activity. Prescription of theoptimal ozone dose must nonetheless be the subject of a preliminary study foreach type of water.

In the actual conditions of use at an industrial scale, ozonation seems to havea limited effect, from 5 to 15%, on abatement of the TOC content. Filtrationthrough saturated activated carbon can provide a complementary study for eachtype of water.

Ozonation's position, upstream or downstream of the filters, would not make forquantitatively significant differences in TOC reduction; but the mechanisms whichwould be working in the activated carbon would not be the same in both cases,making for differences in the nature of organics present in distributed water.

Our objectives being to minimize the nutrients for bacteria in distribution sys-tems and to reduce the amount of chlorine injected at the end of treatment, theozone + activated carbon treatment is the best adapted, and our research aimsat optimizing this combination by focusing on oxydation, contact times andadaptation of activated carbon to biosorption phenomena.

Key words

Water treatment, ozonation of water pollutants, activated carbon filtration,organics, biodegradability.

Rgsume

Les essais en laboratoire corroborent 1'amelioration qu'apporte 1'ozonation dans1'Elimination de la micropollution organique de l'eau de surface par le charbonactif. Le taux d'ozonation optimum correspond a la stabilisation de la diminutionde 1'absorption UV. La postozonation ame'liore la filtration, et I1 analyse parHLPC montre que la cause r£elle reside dans la degradation des composes organiquesen produits moins adsorbables due a une augmentation d'activite bacterienne telleque le montrent des mesures d'ATP, de dSshydrogenase, et la respiromStrie.

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r Influence of Ozonation on Pollutants 31

Laboratoriumversuche beweisen dass Ozonisierung die Entfernungvon organischen Mikroverschmutzern aus Oberflachenwassern durchFiltration rait Aktiv-Kohle verbessert. Optimale Ozondosierungenentsprechen der Stabilisierung der asymptotischen Verminderungder UV - absorption. Die Verbesserung in der kornigen Aktiv-Kohle-filtration wird durch vergrosserte Bakterienaktivita't erreicht.

References

1 R.G. RICE, Ozone gives boost to act ivated carbon, Water and Sewage Works,April (1980)

2 P. SCHOLHOF, An evolutionary approach to activated carbon treatment, JAWWA,643-659, Nov. (1979)

3 EPA/PTI, Report Ozonews, Oxidation products of organics s t i l l l i t t l e known,Ozonews, Vol 7, 5 (1979)

4 E. GILBERT, Reaction of ozone with organic compounds in d i lu te aqueous solu-t ion . Ident i f ica t ion of the i r oxidation compounds. Congress on Ozone/chloridedioxide oxidation products of organic mater ia l s , 227-242, IOA, Cincinnati(1976)

5 B. LEGUBE, B. LANGLAIS, B. SOHN, H. DORE, Identification of ozonation pro-ducts of aromatic hydro-carbon micropollutants: effect on chlorination andbiological filtration, 5th World Ozone Congress, IOA, Berlin (1981)

6 M. DORE, B. LANGLAIS, B. LEGUBE, Mechanisms of the reaction of ozone withsoluble aromatic pollutants, Ozone Science and Engineering, Vol 2, 1,39-54 (1980), 4th World Ozone Congress, IOA, Houston (1979)

7 P. WERNER, Private communication (1980)8 P. STEPHENSON, A. BENEDEK, M. MAMAIYANDI, E.A. LANCASTER, The effect of

ozone on the biological degradation and activated carbon adsorption ofnatural and synthetic organics in water. Part 1: Ozonation and biodegrada-tion, Ozone Science and Engineering, Vol 1, 263-279 (1979)

9 E. GILBERT, Transformations chimiques et produits de reaction forme's lorsde 1'ozonation des constituants organiques de l'eau, Congres sur les proce-des d'oxydation appliques au traitement de l'eau potable, Karlsruhe (1978)

10 J. HOIGNE, H. BADER, Rate constants for reactions of ozone with organicspollutants and ammonia in water, Symp. on advanced ozone technology, Toronto(1977)

11 R.G. RICE, Ozone for the treatment of hazardous materials, 73rd AnnualMeeting American Institute of Chemical Engineers, Chicago (1980)

12 E. NIKI, Y. YAMAMOTO, H. SHIOKAWA, Y. KAMIYA, Ozonation of phenol in water,Water and Wastewater Treatment Session of the Ozone Technology Symp. andExposition, IOA, Los Angeles (1978)

13 J.P. GOULD, W.J. WEBER, Oxidation of phenols by ozone, JWPCF, 48(1), 47-60,(1976)

14 H.R. EISENHAUER, Dephenolization by ozonolysis. Water Research, 5, 467-472(1961)

15 P.P.K. KUO, E.S.K. CHIAN, B.J. CHANG, Identification of end products resul-ting from ozonation and chlorination of organic compounds commonly found inwater. Environmental Science and Engineering, Vol 11, 3, 1177-1181 (1977)

16 H. LIENHARD, H. SONTHEIMER, Influence of process conditions on the effectof ozone treatment of organic substances in the water. Ozone Science andEngineering, Vol 1, 62-72 (1979)

17 M. SCHALEKAMP, K. DIETLICHER, J. VALENTA, R. WATTENHOFER, U. ZIMMERMANN,L'evolution des polluants organiques specifiques dans les eaux de surfaceet au cours de la preparation de l'eau potable. Gas Wasser Abwasser, 58,11, 633-643 (1978)

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32 R. Brunet et al.

18 D. Van der KOOIJ, The determination of the after growth possibilities ofbacteria in drinking water, Proc. of the seminar on development methodsfor determining water quality, KIWA Ltd and VWN, 6-8 (1978)

19 R. BRUNET, H.M. BOURBIGOT, B. LEGUBE, M. DORE, Evolution chlmique desmatieres organiques au cours de l'ozonation d'une eau de surface filtree,Aqua, 4, 76-77, 13e Congres AIDE, Paris (1980)

20 K. GAID, G. MARTIII, Th. BERNARD, Evolution physico-chimique et biologiqued'un substrat marque (phenol) apres son adsorption sur charbon actif (inprocess of publication)

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the influence of the ozonation dosage on the structure and biodegradability of pollutants in water,...

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