2003_J.perkowski_Decolouration of Model Dyehouse Wastewater With Advanced Oxidation Processes

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67FIBRES & TEXTILES in Eastern Europe July / September 2003, Vol. 11, No. 3 (42)

IntroductionDecolouration is one of the basicindicators that describe the quality ofwater used both in households andindustry. Most dyes and pigmentsoccurring in nature and used inindustry do not reveal any direct hightoxicity in relation to living organisms,including man. As they usually occurat low concentrations in wastewaterand in water , it may be presumed thatremoving dyeing substances from wateris not a specially dif cult and important

problem. However, this is not so. Thedisturbance of biological processes insurface water induced by changes incolour and intensity is a serious problem.This leads to changes in the quantity oflight penetrating deeper water layers andthe related changes in biological life.Another problem which should not beneglected either is the aesthetic aspectrelated to tourism and recreation.

So, decolouration is important both inwastewater treatment technology andwater conditioning. In general, almostall branches of industry dispose dyestuffsinto sewage. Their type and quantityvary, and mainly depend on the typeof industrial plant, production size andassortment, and also the technologyapplied. Undoubtedly, most dyestuff isstill discharged by the chemical industryin connection with the production ofdyestuff, and by the textile industry inwhich dyestuffs are used.

Naturally, it would be most advantageousto remove all the impurities containedin wastewater and to obtain pure water.However, the costs of such an operationwould be very high and not always

Decolouration of Model DyehouseWastewater with Advanced OxidationProcesses

Jan Perkowski,Lech Kos*

Technical University of d,Institute of Applied Radiation Chemistry,

Wrblewskiego 15, 94-046 d, PolandTel (+48) 42-6313 181, Fax (+48) 42-6840 043,

E-mail: [email protected]*Institute of Knitting Technology

and Techniques,Piotrkowska 270, 90-361 d, Poland

Tel (+48) 42-6847 449,Fax (+48) 42-6370 218,

E-mail: [email protected]

AbstractThe article presents the results of dye decomposition in model dyehouse wastewater. Differentversions of the process of advanced oxidation were used for decolouration. Such agents asozone, hydrogen peroxide, UV and gamma radiation, and various combinations of these,were applied. In all those processes, the main oxidising agent was the hydroxyl radical.

For model dyehouse wastewater, the effectiveness of decolouration reaction induced bydifferent versions of the process of advanced oxidation was compared. The most effectiveversion of the advanced oxidation processes proved to be the simultaneous use of all threeagents. In the case of this treatment of dyehouse wastewater, a nearly complete decoloura-tion was obtained.

Key words: model wastewater, decolouration, advanced oxidation, ozone, gamma radiation.

justi ed. This is the case with colouredsolutions. In some technological cycles,e.g. in dye industry, it is necessary onlyto remove the colour completely, andsometimes it is necessary to purify waterslightly to enable its re-use as coolingor technological water. This enables theclosing of water circulation in factories,which results not only in economic butabove all ecological advantages.

An attempt to increase the ef ciencyof decomposition of the impurities

present in the wastewater and to improvethe economics of the process resultsin research on advanced oxidation

processes in which advantage is taken ofsuch factors as UV and gamma radiation,as well as the use of ozone and hydrogen

peroxide either separately or jointlyin double or treble combinations. Theliterature describes the positive results ofthis method, both in reference to dyestuffsolutions [1-4] and various types ofwastewater [5-8].

At this stage of our research, we present the results of experiments withthe decolouration of a model textilewastewater, a dyebath, using differentversions of advanced oxidation. Adetailed description of the experimenthas been presented in our earlier studies[9-10]. This paper is a continuation ofthe studies on decolouration of watersolutions that include works on themechanism of primary oxidation reactioninitiated by hydroxyl radicals [11] and thedevelopment of a mathematical model

of the decolouration occurring whendifferent versions of advanced oxidationwith UV and gamma radiation, oxygen

peroxide and ozone are used [11].

The Mechanism of AdvancedOxidation Processes

It is postulated that the mechanism ofcombined action of ionising radiation andozone is related to a simultaneous use ofreactive products of water radiolysisand ozone decomposition in water. Thiseffect was observed for the rst time inwater solutions of phenol and ethyleneglycol [12]. The results are similar whenozone and UV radiation are used jointly.

Ozone decomposition in the aqueoussolution gives rise to the formation of

peroxide HO 2 radicals, then hydroxylOH radicals:

O3 + H 2O HO 3+ + OH - (1)

HO 3+ + OH - 2 HO 2 (2)

HO 2 + O 3 OH + 2 O 2 (3)At the same time, the primary productsof water radiolysis, which were formedas a result of ionising radiation, also form

peroxide HO 2 radicals in the reactionswith oxygen dissolved in the system.

H2O H + OH + e aq- (4)

H + O 2 HO 2 (5)

eaq- + O 2 O2- (6)

O2- + H + HO 2, pK=4.88 (7)

When the quantity of ozone in the systemis suf cient, as in reaction (3), the HO 2 radicals formed during water radiolysisare transformed into OH radicals. So,in water solutions exposed to ozoneand ionising radiation, apart fromthe low-yield reactions of immediatedecomposition of organic substances(8), rst of all their decomposition willtake place, caused by the hydroxyl OH radicals that were formed during waterozonolysis and radiolysis.


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RH R + H (8)

RH + OH R + H 2O (9)

R + O 2 RO 2 (10)

On the other hand, while reacting withozone, the organic peroxide RO 2 radicals

are transformed into RO.

radicals; RO 2

. + O 3 RO. + 2 O 2 (11)

RO + RH R + ROH (12)

So, the less reactive RO 2 and HO 2 radicals are transformed into morereactive HO and RO

radicals (3 and

11). Due to their properties, the rateof oxidation of organic compoundsincreases. The dominant role of HO radicals in the combined method iscon rmed by the results of an experimentwith the use of radical scavengers. Thevalues of decomposition yield of phenoland ethylene glycol determined in theradiation-ozonation method indicate thatthe reaction has a chain nature.

Similar processes of organic compoundoxidation, with a predominant role for thereaction of hydroxyl radicals, take placein advanced oxidation. The mechanismfor generating HO radicals in waterand their restoration in chain reactionswith ozone, hydrogen peroxide and UVradiation has been presented by Benitez[13]. In the literature, there is a detaileddescription of water radiolysis as well asof the primary and consecutive reactionsthat take place in it [14]. These problemswere also tackled in our studies dedicatedto textile wastewater treatment by meansof advanced oxidation processes [9,15].

A schematic of the oxidation processesof the organic compounds contained inwater induced by hydroxyl radicals isnaturally general, and is identical in allAOP versions where the main or the onlyoxidant is a hydroxyl radical and oxygenis present in the solution. The schematicof such an oxidation process has been

presented elsewhere [16].

Materials and MethodsIn the experiments, model dyehousewastewater was used. It contained: anthraquinone dye, polan blue E2R

(acid blue 62, C.I. 62045) - 0.04 g/dm 3

azo dye, helion yellow G (directyellow 44, C.I. 29000 ) - 0.03 g/dm 3

azo dye, brown RC (direct brown 2,C.I. 22311) - 0.03 g/dm 3

anionic detergent, polanol S - 0.3 g/dm 3 table salt NaCl - 12.5 g/dm 3.

The model dyehouse wastewaterwas strongly concentrated. It wascharacterised by an intense dark greencolour (colour threshold - CT=1000),a high anionic detergent content - ADcontent =142 mg/dm 3, and a chemicaloxygen demand (COD) reaching 440 mg

O2/dm 3. The wastewater was stronglymineralised, and the content of chlorideswas 8000 mg/dm 3. The reaction wasneutral pH=7.5. The colour thresholdnumber was determined according to thePolish Standards.

Advanced OxidationProcesses in Model DyehouseWastewater

A detailed description of the reactionsystem, together with a method of

carrying out the process and results, have been presented elsewhere [9,10,17]. Thefollowing versions of the model dyehousewastewater treatment were applied:ozonation, oxidation with hydrogen

peroxide, UV radiation and gammaradiation, as well as all combinations ofthese agents, i.e. ozone and UV radiation,ozone and hydrogen peroxide, hydrogen

peroxide and UV radiation, radiationand ozone, radiation and hydrogen

peroxide and ozone, hydrogen peroxideand UV radiation. The effects of thegamma radiation dose and exposurerate, reaction and oxygen ow rate werestudied. From the results obtained, thefollowing conclusions on the wastewaterdecolouration can be drawn.

Ozone

The degree of dyestuff decompositionincreases with an increase in the ozonationtime, i.e. with the applied dose of ozone.Already at short reaction times (ozonedoses) a very high colour reduction isobtained. Detailed results of studieson the process of ozonation applied tosolutions of dyestuffs and dyebaths arediscussed in other work [17].

Hydrogen peroxide

In dyehouse wastewater exposed tohydrogen peroxide, decolouration from50 to 83% and from 67 to 90% wasobserved, depending on the quantity ofH2O2 (5 to 20 cm 3

perhydrol per dm 3

wastewater) and treatment time (1 and 2hours). Hydrogen peroxide causes quitegood decolouration of the wastewater,the most signi cant factor being itsconcentration. At large quantities (20cm3/dm 3 wastewater) prolongation of thetreatment time from 1 to 2 hours does notimprove the results of decolouration.

UV radiation

In dyehouse wastewater subjected to UVradiation, decolouration ranged from67 to 75%. The decrease in dyehousewastewater colouration is attributed tothe processes of dyestuff decompositioninduced by the photochemical reactionof oxidation in the presence of oxygen.A slight increase in decolouration at

prolonged exposure times is the resultof secondary decomposition reactionsthat lead to the formation of coloureddecomposition products.

Gamma radiation

Within the research on radiation processof dyebath decolouration, the effect ofthe following factors was investigated:the dose and exposure rate of radiation,aeration and oxidation of the solution,gas ow rates and the pH of the bath.

The effect of exposure rate on thedecomposition of impurities containedin the dyebath was investigated withinthe range from 2.5 kGy (0.25 Mrad) to100 kGy (10 Mrad). Two experimentalseries were performed: in the rst onethe wastewater was not oxygenated (aslight oxygen diffusion from the airover the solution might occur), whilein the second series a constant ow ofoxygen equal to 3 dm 3/h was applied. It

was found that both in the case of non-oxygenated and oxygenated wastewater,an increase in the exposure rate causedan increase in the decomposition ofimpurities. The changes of the mostimportant wastewater parameters areshown in Figure 1.

In the case of the dyebath, irradiationwith 10 kGy without oxygenation isinsuf cient for complete decompositionof dyestuffs. This is indicated by a changein the wastewater colour from dark greeninto brown/yellow and a decrease of only50% in the colour threshold numberCT. A further increase of the dose upto 100 kGy had practically no effect oncolour reduction. Much better results ofwastewater decolouration are obtainedfor oxygenated wastewater. For instance,at the dose 10 kGy and oxygenation rate3 dm 3/h, the colour reduction was 85%.

The effect of exposure rate on thedecomposition of impurities was studiedfor non-oxygenated and oxygenateddyebaths within the range of 0.014 to1.4 Gy/s [10,18]. A clear impact of theexposure rate on the degree of solutiondecolouration can be observed. Betterresults were obtained at low exposure

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rates both in the oxygenated and non-oxygenated systems.

When analysing these results, it wasobserved that the effect of exposurerate was mainly due to a signi cantextension of the reaction time, which

was particularly important in the caseof wastewater oxygenation. A slowerreaction at increased concentrations ofoxygen dissolved in water guaranteesa more ef cient decomposition ofimpurities in water due to radiation.

The effect of oxygen ow rate wasinvestigated within the range of 1dm 3/h to 30 dm 3/h. It was found thatwith an increase in the oxygen owrate, the decomposition of impuritiesalso increased, while the irradiation

parameters remained constant. In thesystems tested it was most advantageousto apply ow rates ranging from 3 to 10dm 3/h, which is seen in Fig. 1. Abovethe rate of 10 dm 3/h dm 3 of solution,no increase in the ef ciency of solutiondecolouration is observed.

Wastewater reaction plays an importantrole in impurities decomposition byradiation. The highest decomposition wasobtained at neutral or slightly alkalinereaction. This dependence occurred in

both oxygenated and non-oxygenated

systems.

As for oxygenation and aeration, theuse of pure oxygen in wastewateroxygenation is too costly a process and

practically not applied on an industrialscale. For this reason, differences inthe ef ciency of the applied dyebathdecomposition by radiation in the caseof oxygenation and aeration should bechecked. Such experiments were carriedout for the dyebath at the gas ow rateof 15 dm 3/h. A comparison was made

for two radiation doses, 10 and 25 kGy.A slight difference in decolouration wasreported at a higher dose, and so the nalcolour threshold number was 130 for airand 97 for oxygen. Hence, it is possibleand economically justi able to use air asan oxidant.

Combined processes

From the different possible combinationsreferring to treatment of the modeldyehouse wastewater, two versions wereapplied: radiation and ozone, and radiation and hydrogen peroxide.

A detailed description of the experimentsand a discussion of the results can befound elsewhere [9,10]. In the case

of the combined action of two agents,ozone and hydrogen peroxide, ozoneand UV radiation, and UV radiationand hydrogen peroxide, and also of thethree agents, ozone, UV radiation andhydrogen peroxide, the process andresults have been discussed in [19-27].

g radiation and hydrogen peroxideThe effect of hydrogen peroxide ondyestuff decomposition in the irradiateddyebaths was investigated, by addingfrom 0.5 to 1.5 cm 3 30% H 2O2 solution per 1 dm 3 of wastewater, andnext irradiating it with 10 and 25 kGyrespectively. The combined use ofhydrogen peroxide and gamma radiationin the dyehouse wastewater causes itsdecolouration. For 1.5 cm 3 perhydrol

per 1 dm 3 wastewater and a radiationdose of 25 kGy, a 95% reduction of thecolour threshold number was obtained.However, this decrease is only slightlyhigher, reaching 90%, when solelyhydrogen peroxide is used, or 50% whenradiation without aeration is applied. Acombined action of hydrogen peroxideand gamma radiation improves dyebath

biodegradability.

g radiation and ozoneThe results of our studies on thetreatment of model dyehouse wastewaterwith ozone and radiation have beendiscussed in detail elsewhere [10,27].The preliminary investigation was aimed

at verifying the applicability of themethod and its optimal implementation.We had to establish whether there wereany differences when ozonation is used

jointly with irradiation, or separatelyat subsequent stages. Therefore, thewastewater was subjected to thefollowing procedure: ozonation (justfor comparison), rst irradiation andthen ozonation (variant I), ozonationand next irradiation (variant II), and

nally simultaneous ozonation andirradiation (variant III). This researchwas mainly of technological signi cance,

because it enabled future adaptationof the technology to speci c industrialconditions.

As seen in Figure 2, the joint applicationof ozone and radiation gave much

better decomposition of impurities, ascompared to the case when each processwas used separately.

The effect of the time of -irradiation,ozonation and simultaneous ozonationand -irradiation are presented in Figure3. The best results of treatment wereobtained when ozonation and irradiationwere used jointly (variant III), and a

positive synergetic effect was observed.

Ozone and UV radiation

In dyehouse wastewater subjected to thecombined treatment, a signi cant colourreduction of between 88 and 98.3% wasobtained. These results are very similarto those obtained during the ozonation

process alone. It seems that in ourexperimental conditions the role of UVlight is insigni cant.

Hydrogen peroxide and UV radiationIn dyehouse wastewater subjected to thecombined treatment, a 96.7 to 99.2%

Figure 1. The effect on colour threshold ( C T) of exposure rate for the dyebath: non-oxygenated, oxygenated (left) and effect of air ow rate (right). Dose rate 0.33 Gy/s. Left- ow rate 3 dm 3 /h, right - radiation dose 5 kGy.

dose, kGy flow rate, dm 3/h

,


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colour reduction was obtained during1 h treatment and 99.2 to 99.5% after 2hours, so the wastewater was practicallytotally decoloured. In this variant, theeffect of UV light on the action ofhydrogen peroxide is very distinct bothin the treatment time of 1 and 2 hours.

Hydrogen peroxide and ozoneIn dyehouse wastewater subjected to thecombined treatment, practically totaldecolouration was obtained. Colourreduction ranged from 98.3 to 98.8%over the treatment time equal to 1 h, andfrom 98.3 to 100% after 2 h.

Hydrogen peroxide, ozone and UVradiationWhen three oxidising agents were usedsimultaneously, the dyehouse wastewaterwas completely decoloured during 1 htreatment.

Final ConclusionsIn the case of dyehouse wastewater, nodistinct positive effect of the simultaneousaction of three factors on decolouration

process is observed, although such aneffect is very clear in reference to otherwastewater parameters. This follows froma very quick process of decolourationand small doses of oxidants necessaryto achieve decolouration exceeding 90%.

To obtain good results, it is suf cient touse a small dose of hydrogen peroxide

below 5 cm 3/dm 3 of wastewater. Anincrease in the amount of H 2O2 resultsin the deterioration of model wastewaterdecolouration.

The results obtained show that the methodsof advanced oxidation are very ef cientin wastewater decolouration. Most

ef cient appeared to be a simultaneoususe of three oxidants. In the case ofsuch treatment, total decolouration ofthe dyehouse wastewater was achieved.Very good treatment results were alsoobtained when using hydrogen peroxide

and ozone jointly. However, they did notdiffer from the results obtained when allthree agents were used simultaneously.Worse treatment results were obtainedwhen applying O 3 and UV (Figure 4).Very good decolouration was achieved

by using only wastewater ozonation,which might con rm the role of this

process in dyestuff decomposition (thedestruction of chromophores) in watersolutions.

References

1. M. Matsui, Ozonation, chapter 3, Envi-ronmental Chemistry of Dyes and Pig-ments, 1996 John Wiley & Sons, Inc. pp.43-60.

2. Y. Yang, D.T. Wyatt II, M. Bahorsky,Decolourization of dyes using UV/H 2 O2

photochemical oxidation, Textile Chemistand Colourist 27, vol. 30, no. 4, April1998, 27-35.

3. S. Ledakowicz, R. ya, J. Perkowski,Ozonation versus advanced oxidation

of acid red 27 Proceedings of the 15 th Ozone World Congress London, UnitedKingdom 11-15 September 2001, vol. II,

pp. 214-224.4. M. Hosono, H. Arai , M. Aizawa, I.

Yamamoto, K. Shimizu, M. Sugiyama,Decolouration and degradation of azodye in aqueous solution supersaturatedwith oxygen by irradiation of high-energyelectron beams, Appl. Radiat. Isot. 1993,44, 9, 1199-1203.

5. R.G. Rice, Applications of ozone for in-dustrial wastewater treatment - a review,Ozone Science and Engineering 1997,18, 477, Ozone - advanced oxidation

processes - cur rent commer cia l re-alities, Proceedings of the 13 th OzoneWorld Congress, Kyoto, Japan, 1997,

pp. 559-564.6. K. H. Gregor, Oxidative decolourization

of textile waste water with advanced,Chemical oxidation technologies forthe nineties, vol. 2 edited 1992 by W.W.Eckenfolder, A.R. Bowers, J.A. Roth.Lancaster. Basel.

7. F. Luck, A. Maret, H. Paillard, A review ofindustrial applications of advanced oxida-tion processes for water treatment, DownUnder 96, Proceedings, Australia.

8. N. Getoff. Radiation - induced degrada-tion of water pollutants - state of the art,Rad. Phys. Chem. 1996, 47, 4, 581-593.

Figure 2. The effect oftreatment method on thecolour threshold number,CT, of the dyebath;1 - crude wastewater,2 - irradiated, 3 - irra-diated and oxygenated,4 - irradiated and thenozonated, 5 - ozonatedand next irradiated,6 - ozonated, 7 - bothozonated and irradiated.

Dose 5 kGy, exposure rate0.33 Gy/s, ozone concen-tration 1460 mg/dm 3h.Gas ow rate 10 dm 3 /h.

Figure 3. The effect of the time of irradiation ( ), ozonation ( ), and simultaneous ozonation and irradiation ( D ) on the colour thresholdof the dyebath (expressed in percent of deacy). Dose rate 0.33 Gy/s,ozone supply rate 145 mg/dm 3h.

Figure 4. Comparison of CT changes in the dyehouse wastewaterobtained for different variants of the advanced oxidation process(AOP); 1- untreated, 2 - O 3 , 3 - H 2O2 , 4 - UV, 5 - g (25 kGy), 6 - g ++ O 2 (25 kGy), 7 - O 3 + UV, 8 - g + O 3 (5 kGy), 9 - O 3 + H 2O2 , 10- UV + H 2O2 , 11 - O 3+ UV + H 2O2.

reaction time, h

colourthreshold, %

reaction time, h version of AOP

percent of initialvalue

colour thresehold,%


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9. J. Perkowski, L. Kos, S. Ledakowicz. Advanced oxidation of textile wastewa-ters, Ozone Sci. & Eng., 22, 5, 535-550(2000).

10. J. Perkowski, L. Kos, Gamma-irradiationcombined with ozonization as a methodof decomposition of impurities in textilewastes, Environment. Protec. Eng., 18,(3-4) 5-17 (1992).

11. J. Perkowski, L Kos, S. Ledakowicz, R.ya, Decomposition of anthraquinonedye Acid Blue 62by advanced oxidation

process, Fibres & Textiles in Eastern Eu-rope, Vol. 11, No 2(41)/2003, pp. 85-91.

12. A. Sakumoto, T. Miyata, Treatment ofwaste water by combined technique ofradiation and conventional method, Rad.Phys. Chem, 1984, 24, 1, 99.

13. F.J. Benitez, J. Beltran-Hereida, T.Gonzalez, J.L. Ascero, Advanced oxi-dation processes in the degradation ofcyanazine, Ozone, Sci. & Eng. 1995, 3(17), 237-258.

14. C.D Jonah, A short history of the radiationchemistry of water, Radiation. Research1995, 144, 2, 141-147.

15. S. Ledakowicz, J. Perkowski, R. Macie- jewska, Application of advanced oxida-

tion processes to textile wastewater, 3 rd Int. Conf. on Advanced Oxidation Tech-nologies for Water and Air Remediation,Cincinnati, Ohio, USA 1996, 147.

16. J. Staehelin J. Hoigne, Reaktionsme-chanismus und Kinetik des Ozonzerfallsin Wasser in Gegenwart organischerStoffe, Vom Wasser, 61, Band 1983 pp.337-348.

17. J. Perkowski, L. Kos, S. Ledakowicz, Ap- plication of ozone in textile wastewatertreatment, Ozone, Sci. & Eng 1996, 18,73-85.

18. J. Perkowski, J. Rouba, L. Kos, In uenceof ionising radiation g on decompositionof tinctorial pollution, Gospodarka Wodna1988, 4 (48), 92 -94.

19. J. Perkowski, J. Rouba, L. Kos, Radiatio-nal and chemical decomposition of con-taminants in textile ef uents, PrzegldWkienniczy 1986, 4 (40), 148-150.

20. L. Kos, J. Perkowski, Application of ozoneand UV-radiation in textile wastewater tre-

atment, Fibres & Textiles 1999, 1, 61-64.21. L. Kos, J. Perkowski, Application of

ozone and hydrogen peroxide in textilewastewater treatment, Fibres & Textiles1999, 2, 61-64. Received 19.02.2003 Reviewed 26.03.2003

22. L. Kos, J. Perkowski, Simultaneousapplication of H 2 O2 and UV or O3, H 2 O2 and UV in textile wastewater treatment,Fibres & Textiles 1999, 3, 57-61.

23. L. Kos, J. Perkowski, Advanced oxida-tion process in the technology of textilewastewater treatment, Fibres & Textiles2000, 1, 66-70.

24. L. Kos, J. Perkowski, S. Ledakowicz, Theeffect of pH on pollutant degradation intextile wastewater treated with the advan-ced oxidation method, Fibres & Textiles2000, 2, 69-73.

25. L. Kos, J. Perkowski, S. Ledakowicz, Theeffect of H 2 O2 concentration on pollutantdecomposition in textile wastewater tre-ated with the advanced oxidation me-thod, Fibres & Textiles 2000, 3, 80-83.

26. L. Kos, J. Perkowski, S. Ledakowicz,The effect of temperature on advancedoxidation of dyeing wastewater, Fibres& Textiles 2001, 2, 66-69.

27. J. Perkowski, L. Kos, D. Dzig, The use

of ozone and ionising radiation for the puri cation of textile wastes, PrzegldWkienniczy 1987, 8 (41), 311-315.

2003_J.perkowski_Decolouration of Model Dyehouse Wastewater With Advanced Oxidation Processes

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