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三氯生在污水深度处理技术中的氧化产物--water research

三氯生在污水深度处理技术中的氧化产物--water research
三氯生在污水深度处理技术中的氧化产物--water research

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Ozonation products of triclosan in advanced wastewater treatment

Xijuan Chen a ,Jessica Richard b ,Yaling Liu c ,Elke Dopp b ,d ,Jochen Tuerk e ,Kai Bester f ,*

a

Department of Biotechnology,Chemistry and Environmental Engineering,Aalborg University,Aalborg,Denmark b

Institute of Hygiene and Occupational Medicine,University Hospital Essen,Germany c

University Duisburg-Essen,Department of Chemistry,Essen,Germany d

IWW Rheinisch-Westfa ¨lisches Institut fu ¨r Wasserforschung GmbH,Mu ¨lheim,Germany e

Institut fu ¨r Energie-und Umwelttechnik e.V.,IUTA (Institute of Energy and Environmental Technology),Duisburg,Germany f

Environmental Science,Aarhus University,Roskilde,Denmark

a r t i c l e i n f o

Article history:

Received 26April 2011Received in revised form 23January 2012

Accepted 28January 2012Available online 7February 2012Keywords:Triclosan Ozone

Ozonation products 2,4-dichlorophenol Toxicity

a b s t r a c t

Triclosan is an antimicrobial agent widely used in many household and personal care prod-ucts.Widespread use of this compound has led to the elevated concentrations of triclosan in wastewater,wastewater treatment plants and receiving waters.In this study removal of triclosan by aqueous ozone was investigated and the degradation products formed during ozonation of an aqueous solution of triclosan were analyzed by GC-MS and HPLC-MS/MS.The following transformation products have been identi?ed:2,4-dichlorophenol,chloro-catecol,mono-hydroxy-triclosan and di-hydroxy-triclosan during treatment process.Cyto-toxicity and genotoxicity of pure triclosan and 2,4-dichlorophenol have been investigated and the results showed reduced genotoxic effects after ozonation,though the respective chlor-ophenol is harmful to aquatic organisms.

a2012Elsevier Ltd.All rights reserved.

1.Introduction

Triclosan (2,4,40-trichloro-20hydroxydiphenylether,CAS:3380-34-5)is currently used as an antimicrobial agent in toothpaste,mouthwash,liquid soap and in functional clothing such as functional shoes and underwear (Engelhaupt,2007).It is also used as a stabilizing agent in a multitude of detergents and cosmetics and as an antimicrobial agent in polymeric food cutting boards (Adolfsson-Erici et al.,2002;Dann and Hontela,2011).Approximately 1500t are produced annually world-wide,and approximately 350t of those are applied in Europe (Singer et al.,2002).The primary emission route for triclosan after usage is through wastewater.In fact,investigators have

detected triclosan in numerous municipal wastewater in?uent samples at concentrations in the range of 0.5e 4.5m g L à1(Buth et al.,2011;Lindstro ¨m et al.,2002).In wastewater treatment plants (WWTPs)90%of the incoming triclosan was removed from the water (Bester,2003,2005;Heidler and Halden,2008;Singer et al.,2002),which is a high but not complete removal.As a result,it has been found in some sewage treatment plant ef?uents as well as in surface water and ground water in many countries (Adolfsson-Erici et al.,2002;Balmer et al.,2004;Bester,2005).In addition,it has been detected in ?sh,soil and sediments due to its hydrophobicity (Coogan et al.,2007;Lozano et al.,2010;Xie et al.,2008).

*Corresponding author .Tel.:t4587158552.E-mail address:kb@dmu.dk (K.

Bester).

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w a t e r r e s e a r c h 46(2012)2247e 2256

0043-1354/$e see front matter a2012Elsevier Ltd.All rights reserved.doi:10.1016/j.watres.2012.01.039

Triclosan inhibits bacteria growth by blocking biosynthesis of lipids,which is necessary for building cell membranes and reproduction(Levy et al.,1999;Schweizer,2001).The impact of triclosan on aquatic organisms and the ecosystem in general has been investigated in several in vivo studies.These studies showed that triclosan is toxic to?sh(Lindstro¨m et al.,2002), algae(Wilson et al.,2003)and other aquatic organisms(Orvos et al.,2002).Algal toxicity was shown at a minimum concen-tration of0.15m g Là1for up to13days of exposure and community changes were visible even at0.015m g Là1(Wilson et al.,2003).The EC50of triclosan in?sh is between240and 410m g Là1(Lindstro¨m et al.,2002;Orvos et al.,2002).In vitro studies on human gingival cells reported toxic effects at concentrations between4.3and28.96mg Là1depending on the test and the exposure time(Zuckerbraun et al.,1998). Acute toxic effects were found to start at0.28m g Là1using the bioluminescent bacteria Vibrio?scheri(Farre et al.,2008). In addition to these toxic effects it was reported that triclosan and its degradation products show endocrine disrupting effects(Foran et al.,2000;Ishibashi et al.,2004;Raut and Angus,2010).The toxicity of2,4-dichlorophenol was previ-ously investigated by Ensley et al.(1994)who found EC50 values of6.5mg Là1in Lemna gibba.

As conventional wastewater treatment processes are unable to act as a reliable barrier concerning triclosan,it is discussed to introduce additional advanced treatment technologies in the areas where a pollution problem concerning triclosan and other persistent organic pollutants has been recognized or is antici-pated.Ikehata et al.(2008)and Ternes et al.(2003)have evaluated different technologies including ozonation and advanced oxidation processes,membrane bioreactors,membrane?ltra-tion and activated carbon adsorption,suggesting that chemical oxidations using ozone is a highly effective treatment process for a wide spectrum of emerging organic pollutants,including pesticides,pharmaceuticals,personal care products,surfac-tants,microbial toxins and natural fatty acids.Ozone(O3)is a very powerful disinfecting and deodorizing gas.The ability of ozone to disinfect polluted water was recognized in1886by de Meritens(Vosmaer,1916).However,the widespread introduc-tion of ozone to remove pollution from drinking water started in the1960s(Langlais et al.,1991).Nowadays,ozone is used in removing bacteria,viruses,algae and fungi as well as sulfur,thus also eliminating taste and odor problems,as well as oxidizing and mineralizing organic chemicals concerning drinking water(Langlais et al.,1991).

Ozonation has recently emerged as an important tech-nology for the oxidation and destruction of a wide range of organic pollutants in wastewater as well(Ikehata et al.,2006). It has been proven to be an effective post-treatment technique for pharmaceuticals and personal care products(Carballa et al.,2007;Ikehata et al.,2008;Lee and von Gunten,2010; Wert et al.,2009;Snyder et al.,2006).

Although ozonation of organic pollutants in wastewater has been investigated in numerous studies,data on the removal of triclosan and eventual formation of by-products are scarce and incomplete and they are mainly focused on the effect and kinetics of triclosan oxidation by aqueous ozone. Suarez et al.(2007)investigated that nearly100%of triclosan depletion was achieved for a4mg Là1O3dose applied to a wastewater containing7.5mg Là1of DOC,while Wert et al.(2009)reported that>95%triclosan removal was indepen-dent of water quality when the O3exposure was measurable (0e0.8mg min Là1).However,Levy et al.(1999)investigated that the antibacterial activity of triclosan is derived primarily from its phenol ring,via van der Waals and hydrogen-bonding interactions with the bacterial enoyl e acyl carrier protein reductase enzyme.The characterization of the reaction path-ways of the ozonation of triclosan is currently rather unclear. Furthermore,it is essential to understand all possible trans-formation products to enable a full risk assessment especially considering toxicological classi?cation.

The objective of this work was to study the reaction prod-ucts of triclosan formed during ozonation treatment.Addi-tionally,the toxicity of selected by-products was investigated to evaluate the oxidative post-treatment technique with ozone in removal of triclosan in water and wastewater systems.

2.Materials and methods

2.1.Standards and reagents

Triclosan was purchased from Ehrenstorfer(Augsburg, Germany)with purity being!99%according to the supplier. Methanol,Toluene,Acetone,Methyl-tert-butyl ether(MTBE) were used in residue grade quality and purchased from Merck, Darmstadt,Germany.Triclosan stock solutions were prepared at a concentration of10mg Là1according to its water solubility by dissolution of the solid compound in water(HPLC grade, Baker,Deventer,The Netherlands).

2,4-dichlorophenol,4-chlororesorcinol,and4-chlorocatechol were purchased from Sigma Aldrich.

O3stock solutions were prepared by purging an O3-containing gas stream through HPLC water.The O3-containing gas stream was produced by passing air through an O3generator (Enaly1000BT-12,Enaly M&E Ltd,Shanghai,China)at constant ?ow rate of0.5L minà1.According to UV e Vis spectrophotom-etry(Shimadzu,Duisburg,Germany),the concentration of O3 stock solution was2mg Là1.

In the toxicity tests the Chinese hamster ovary cells (CHO-9)were used and MTT(Sigma,St.Louis,USA)was used in the cytotoxicity test.

2.2.Ozonation and extractions

Samples were prepared by mixing O3stock solutions into triclosan stock solutions in different volume ratios to reach the molar ration of triclosan:O3in1:1,1:3and1:5.All samples were extracted after the reaction performed at room temperature overnight.The pH of the water used was7?0.5.It was measured at the beginning of the experiments as well as at the end.

Samples were extracted by solid phase extraction(SPE) using polymeric cartridges(Strata-X,Phenomenex,Aschaf-fenburg Germany).Before the extraction,the SPE cartridges were rinsed with6mL methanol and6mL HPLC-grade water. After loading the samples to the cartridges,they were eluted by methyl-tert-butyl ether(MTBE)for analysis by gas chromatography-mass spectrometry(GC-MS),whereas duplicate samples were eluted by methanol for analysis by

w a t e r r e s e a r c h46(2012)2247e2256 2248

high performance liquid chromatography-mass spectrometry (HPLC-MS/MS).

2.3.Analytical methods

Samples eluted by MTBE were analyzed by gas chromatog-raphy with mass spectrometric detection(GC-MS)equipped with a programmable temperature vaporizer(PTV)injector. The PTV(1m L injection volume)was operated in PTV splitless mode.The injection temperature of115 C was held for3s,it was successively ramped with12 C sà1to280 C for the transfer of the analytes.This temperature was held for 1.3min.The injector was then ramped with1 C sà1to300 C which was held for7min as a cleaning phase.

The GC separation was performed with a DB-5MS column (J&W Scienti?c,Santa Clara,United States),L:15m;ID: 0.25mm;?lm:0.25m m using a temperature programme of: 100 C(hold:1min)ramped with5 C minà1to220 C and with 30 C minà1successively to280 C.Finally,the baking temperature280 C was held for7min.Helium(5.0)was used as a carrier gas with a?ow rate of1.3mL minà1.The transfer line was held at250 C,which is suf?cient to transfer all compounds from the GC into the MS as the vacuum builds up in the transfer line.The ion source of the mass spectrometer (DSQ,Thermo Finnigan,Dreieich,Germany)was operated at 230 C in electron impact mode.The MS was used in full scan mode from50Da to600Da and the detector was operated with1218V.

The samples eluted by methanol were analyzed by liquid chromatography with tandem mass spectrometric detection (HPLC-MS/MS).The separation was performed using a Phe-nomenex synergi4u polar-RP column(150?2mm I.D., particle size4m m).The?ow rate was0.25mL minà1.The LC gradient was established by mixing two mobile phases:phase A,HPLC water and phase B,Methanol.The chromatographic separation was achieved with the following gradient:0e2min 100%A,changing to100%B in30min,32e36min100%B.The injection volume was10m L.

The LC system consisted of a UltiMate3000autosampler (WPS-3000T SL),a UltiMate3000pump(DG-3600M),a UltiMate 3000column compartment hold(TCC-3000RS)on20 C(all from Dionex,California,United States).After LC separation,the analytes were determined by an AB-Sciex(California,United States)API4000triple quadruple mass spectrometer using electrospray ionization in negative mode with full scan from 130Da to400Da utilizing the primary quadrupole.Nitrogen was used as a drying(at400 C)nebulizing and collision gas.One scan per second was recorded.

2.4.Toxicity tests

2.4.1.Cell culture

The Chinese hamster ovary cells(CHO-9)were cultured in HAM’s F12medium supplemented with10%Foetal Calf Serum,0.5%gentamycin and0.5%L-glutamine at37 C and5% CO2conditions.

2.4.2.Exposure

Triclosan and2,4-dichlorophenol were tested between0.5and 100m g Là1for24h.2.4.3.Cytotoxicity:MTT test

To detect cytotoxic effects the MTT test was performed using the96-well plate format using100,000CHO-9cells in200m L of HAM’s F12medium in each well.After24h the fresh medium was added and the cells were exposed to the different concen-trations of the two substances for another24h.After the exposure time the medium was removed and100m L fresh medium and10m L MTT solution(5mg MTT dissolved in1mL phosphate buffered saline)(KCl2.67mM,KH2PO41.47mM,NaCl 137.93mM,Na2HPO4$7H2O8.06mM;Invitrogen)were added to each well and incubated at37 C for2h.The medium was then replaced with100m L of lysis solution(99.4mL dimethylsulf-oxide,0.6mL acetic acid[100%]and10g sodium dodecyl sulfate) and the absorption was directly measured at590nm.

2.4.4.Genotoxicity:alkaline comet assay

The alkaline comet assay was performed as described by Ostling and Johanson(1984)and later on revised by Singh et al.(1988) with some minor modi?cations.In short:Microgels were prepared by adding50m L of low melting point agarose(L.M.P. agarose)to a chamber.100,000CHO-9cells were exposed to different concentrations of triclosan and2,4-dichlorophenol for 24h.0.1mg Là1N-ethyl-N-nitrosourea was used as a positive control and added to the cells30min prior to trypsination.After the exposure time the cells were washed,trypsinated and resuspended.45m L of low melting point agarose were mixed with20m L of cell suspension containing8000cells and added on top of the?rst layer of agarose.After solidi?cation the slides were covered with freshly prepared and precooled lysis solution overnight at4 C.Before electrophoresis the slides were incu-bated in electrophoresis solution at4 C for20min.Electro-phoresis was then performed for20min at4 C with300mA. After electrophoresis the slides were incubated in neutraliza-tion solution for30min and afterward dehydrated in ethanol for 2h.Then the slides were stored overnight to let the gels dry completely.DNA was stained with SYBR Greenòand image analysis was performed using the Comet Assay IV Software (Perceptive Instrument,UK)and a CCD(charge coupled device) camera attached to a Leica microscope.All experiments were carried out three times and statistical analysis was performed using the Mann e Whitney test.

3.Results and discussions

3.1.Identi?cation of triclosan ozonation products

In Table1it can be seen that triclosan reacts under all used conditions quantitatively with ozone,thus removal rates of 94e99.9%seem realistic.

However,four major peaks were detected in the gas chro-matogram of a sample extract of ozonized triclosan sample with molar ratio of triclosan:ozone in1:2measured by GC-MS. On the basis of their mass spectra,isomers of dichlorophenol (M1)and chlorocatechol(M2)were identi?ed at the retention time of5.88min and12.7min,respectively.Peaks at retention time of24.99min and28.94min were identi?ed as triclosan and its mono-hydroxylated product(M3).By comparing to a true standard,2,4-dichlorophenol was veri?ed as the major monoaromatic metabolite in GC-MS.The full results of all

w a t e r r e s e a r c h46(2012)2247e22562249

transformation products identi?ed by GC-MS are listed in Table 2.

A chromatogram of a sample with the molar ratio of tri-closan:ozone:1:2measured by HPLC-MS is shown in Fig.1.Similar to the results from GC-MS,dichlorophenol (M1),chlor-ocatechol (M2)and mono-hydroxy-triclosan (M3)were identi-?ed in the chromatogram.They were detected in different ratios by GC-MS and HPLC-MS because of different extraction and detection methods.Additionally,two isomers of chlor-ocatechol (M2)and di-hydroxy-triclosan (M4)were detected by the HPLC-MS measurements.The dichlorophenol (M1)was con?rmed as 2,4-dichlorophenol by comparison to a standard purchased from Sigma Aldrich (Steinheim,Germany),the two isomers of M2were con?rmed as 4-chlorocatechol (4-chloro-1,2-dihydroxybenzene)(M2a)and 4-chlororesorcinol (4-chloro-1,3-dihydroxybenzene)(M2b)by comparison with standards purchased from Sigma Aldrich (Steinheim,Germany).

Other transformation products did not comply with stan-dards by means of the retention time or were not commer-cially available.Therefore,collision-induced dissociation (CID)was used to produce product ion scans for further metabolite identi?cation.For this purpose the [M-H]àion was selected as precursor ion.The HPLC-MS/MS results of the metabolite identi?cation are listed in Table 3.

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Mono-hydroxy-derivatives of triclosan (M3)were detected at 303and 305Da (equivalent to the two main isotope signal for the (M-H)àion)at 27.56min retention time.The product ion scan of 303Da and 305Da provided abundant fragmen-tation for this compound (Fig.2).The identi?cation was con?rmed by the detection of the fragment ion peak at 161corresponding to (C 6H 3OCl 2)à.The two chlorine atoms are being veri?ed by the chlorine isotope distribution in Fig.2C.Further analysis of Fig.2B and C shows that fragments 125Da and 113Da are attributed to [C 6H 2OCl]àand [C 5H 2OCl]àstemming from cleavage of HCl and CHCl from 161respec-tively.It can thus be hypothesized that the oxidation takes place in the triclosan ring with less chlorination.

The molecular ion peak of di-hydroxy-triclosan (M4)was detected with the retention time at 17.65min (Fig.1).The product ion spectrum of M4showed major fragment ion peaks at 161and 125Da,indicating that the double chlori-nated ring is again still intact and not oxidized (Fig.S1).Similar as the fragmentation spectrum of M3,the transformation product identi?cation was further con?rmed by an investi-gation on the chlorine isotope peaks.

3.2.

Structural suggestions and veri?cations

After triclosan was reacted with ozone,some intermediates were identi?ed by using GC-MS and HPLC-MS/MS.On the basis of their GC-MS spectra and HPLC-MS/MS fragmentation,several ozonation products for triclosan are proposed (Table 2

and 3).Triclosan can be oxidized by ozone resulting in OH addition forming mono-hydroxy-(M1)and di-hydroxy-triclosan (M2)and ?nally breaking of the ether bond result-ing in 2,4-dichlorophenol (M1),4-chlorocatechol (M2a)and 4-chlororesorcinol (M2b).

The 2,4-dichlorophenol (M1)is a well known product of triclosan which has been detected by several investigators within biodegradation experiments (Kim et al.,2010),as an oxidative transformation product from reactions with manganese oxides (Zhang and Huang,2003),as well as a photochemical degradation product in both natural and buffered deionized water (Latch et al.,2005).Kim et al.(2010)has found the chlorocatechol (M2),mono-hydroxy-triclosan (M3)and di-hydroxy-triclosan (M4)as biodegradation prod-ucts of triclosan from bacteria.Additionally,Zhang and Huang (2003)have detected that mono-hydroxy-triclosan (M3)could be one of the oxidation products of triclosan by manganese oxides.Except the 2,4-dichlorophenol (M1),none of the other transformation products have been published as ozonation by-products of triclosan,to the best of our knowledge.

3.3.

Ozonation of triclosan

The triclosan chromatograms of the three samples from the experiment are shown in https://www.doczj.com/doc/182891444.html,plete ozonation of tri-closan (but not its transformation products)was detected in the sample with molar ratio of triclosan:ozone ?1:5.Ozona-tion was substantial in the sample with a molar ratio of

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MW: 144

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MW: 162

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monohydroxy-triclosan

MW: 304

Triclosan MW: 288

Fig.1e Chromatogram of sample with triclosan:ozone in 1:2from HPLC-MS/MS (Electrospray ionization in negative polarization ESI (L ))with suggested identi?cation.

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triclosan:ozone ?1:3and less in the sample with molar ratio of triclosan:ozone ?1:1.

2,4-dichlorophenol was detected by GC-MS and HPLC-MS in all the three samples.Levels of 2,4-dichlorophenol in the sample with high ozone amount (molar ration of triclosan:o-zone in 1:3)were,however,lower than the other two samples with lower ozone amount,which indicate that 2,4-dichlorophenol is an intermediate product and can be

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further oxidized.Chromatograms of 2,4-dichlorophenol and triclosan during ozonation showing the somewhat longer presence of 2,4-dichlorophenol are shown in Fig.3.The conversion yields of triclosan to 2,4-dichlorophenol depend on the amount of ozone.Now,these compounds are available they can be studied in biodegradation processes as well.More information can be gained from Fig.S2in which the signal height obtained by HPLC-ESI (à)MS of all identi?ed trans-formation products is plotted against the relative ozone concentration.

3.4.Toxicity of triclosan transformation products in comparison to triclosan

Cytotoxic and genotoxic effects of triclosan and its oxidation by-product 2,4-dichlorophenol were analyzed using the MTT test and the alkaline comet assay.

These two tests are well established toxicity tests and have been used in the testing of chemicals for several decades and they have been proven to be rapid and sensitive methods.The MTT tests give a quantitative measure on the amount of

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Fig.2e HPLC-MS/MS analysis (ESI (L ))of mono-hydroxy-triclosan,A)the full scan spectrum of the mono-hydroxy-triclosan,B)product ion spectrum of the precursor 303of mono-hydroxy-triclosan (the isotopic composition 35Cl 3),C)product ion spectrum of the precursor of mono-hydroxy-triclosan (the isotopic composition 35Cl 237Cl).

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viable and dead cells thus the cytotoxicity of the tested substances resulting in an idea about the general toxicity (Mosmann,1983).DNA damage was measured by the alkaline comet assay which allows the detection of single and double strand breaks as well as alkali labile sites (Singh et al.,1988;Tice et al.,2000).In addition both tests have been previously adapted for the use of CHO (Chinese Hamster Ovary)cells.This is a cell line which has been derived from the ovaries of the Chinese hamster in 1957and widely used in toxicity testing (Puck et al.,1958).

Retention time (min)

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Fig.3e Chromatogram and MS spectra of triclosan and its ozonation product e 2,4-dichlorophenol detected by GC-MS in electron impact ionization.To simplify the graph,the signals for 162and 288Da were added to gain one chromatogram for both 2,4-dichlorophenol (162Da)and triclosan (288Da).Sample 1,triclosan:ozone [1:1.Sample 2,triclosan:ozone [1:3.Sample 3,triclosan:ozone [1:5.

Fig.4e Genotoxic effects of triclosan and 2,4-dichlorophenol on CHO-9cells after 24h of exposure investigated using the alkaline comet assay.Asterisks display the signi?cance in DNA damage increase (p <0.05[*signi?cant;p <0.01[**very signi?cant;p <0.001[***extremely signi?cant).

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Both substances were tested at concentrations between 0and100m g Là1.The results of the MTT test show that neither triclosan nor2,4-dichlorophenol has any cytotoxic effect on CHO-9(Chinese Hamster Ovary)cells after a24h exposure at the used concentrations(data not shown).For each concen-tration the viability lies above90%compared to the negative control.In addition no difference can be seen comparing both substances and their effects on cell viability.

However the results of the alkaline comet assay with triclosan show tail moments increasing with concentrations. Compared to triclosan and the negative control,2,4-dichlorophenol is less genotoxic(Fig.4).This indicates that ozonation is a useful tool in removing the genotoxic compound triclosan from wastewater.However,it should be taken into account that2,4-dichlorophenol is prioritized under the EU surface water directive76/464/EC(European Comission1976)(Umweltbundesamt,2005)and is classi?ed to be“harmful to aquatic organisms”and“may cause long-term adverse effects in the aquatic environment”.

4.Conclusion

Contamination of surface water and ground water with tri-closan is an emerging issue in environmental science and engineering.The outcomes of this study are:

Removal of triclosan from water can be achieved by using ozonation.

The treatment process can eliminate triclosan completely and convert it into the products:2,4-dichlorophenol, chlorocatechol,mono-hydroxy-triclosan and di-hydroxy-triclosan.Increasing the ozone concentrations in the reactions leads to decreased concentration of triclosan as well as its oxidation by-products.

2,4-dichlorophenol shows lower genotoxic effects than triclosan at the tested concentrations,but this compound is classi?ed to be toxic to aquatic organisms.The other transformation products cannot be assessed up to now.

Formation and occurrence of the identi?ed trans-formation products should be investigated at full scale applications

Reactor design should take the formation of oxidation by-products into account and possibly use higher ozone doses or retention times to remove by-products.

Acknowledgment

The authors would like to thank for?nancial support from the Danish Research Council FTP for the project In situ character-ization of microbial degraders of Triclosan and methyl-triclosan from wastewater treatment plants and Aalborg University as well as the German Federal Ministry of Economics and Technology within the agenda for the promotion of industrial cooperative research and development(IGF)based on a decision of the German Bundestag.The access was opened by member organization environmental technology and organized by the AiF,Arbeitsgemeinschaft industrieller For-schungsvereinigungen,Cologne(IGF-Project No.15862N).

Appendix.Supplementary material

Supplementary data related to this article can be found online at doi:10.1016/j.watres.2012.01.039.

r e f e r e n c e s

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《工业废水深度处理与回用技术评估导则》 (征求意见稿) 编制说明 编制单位:轻工业环境保护研究所 二〇一二年四月

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深度处理工艺技术

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水的深度处理工艺课程设计要点

《水的深度处理工艺》 系别:市政与环境工程学院 专业:环境工程 姓名:柴剑雄 学号: 021411114 指导教师:张霞

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—30mg/L、COD含量为 60—100mg/L。采用人工湿地深处理可以实现景观与处理效果相结合的良性循环,通过种植了美人蕉、芦苇、富贵竹、空心菜等湿地植物,通过光合作用去除氨氮等成分,通过种植凤眼莲、空心莲子草、稗草、藨草、黄菖蒲等植物去除工业废水中的有害物质等。生物接触氧化法是是在充氧的污水池中填充填料,用生物膜布满填料,污水以固定流速以埋没生物膜的方式,在微生物作用下除去有害物质的污水深处理方式,应用于农药、石油化工、纺织、印染、食品加工、轻工造纸和发酵酿造等工业废水以及二级出水、生活污水的深处理,去除铁、锰、亚硝酸盐、氨氮等物质;曝气生物滤池通过在生物滤池底部或下部加设曝气装置对污水进行处理的技术,通过该技术处理的污水基本上能够达到杂用水的标准。污水深度处理技术中的膜处理法和物理化学处理法包括混凝技术、活性炭吸附技术、臭氧法、膜分离技术、高级氧化法等。这些污水深度处理技术适用的范围不同,各有所长,又各有所短,因此,在污水深度处理过程中,要充分照顾到各种处理技术的技术特点,扬长避短,综合采用,为污水处理厂取得较好的经济效益和社会效益打下坚实的基础。(二)污水深度处理技术的应用 污水深度处理技术是在污水预处理及主处理的基础上,对二级处理水用物理化学处理法&生物处理法及膜处理法去除二级出水中存留的细菌&重金属等危害人体健康的有害及有毒物质,从而达到污水的回收和利用的一种处理技术其典型处理流程如表:

深度氧化技术在工业废水处理中的应用

深度氧化技术在工业废水处理中的应用 目前,国内大、中型工业废水处理项目主要采用臭氧氧化+曝气生物滤池(BAF)和Fenton 氧化+沉淀过滤这2种深度处理技术。前者适用于废水污染物的臭氧氧化效果好、废水有回用需求的情况,在石油化工、煤化工行业废水处理中,已基本成为了一种标配工艺,后者则适用于废水无回用需求、污泥处置费用低的项目,主要应用于化纤、印染和造纸等行业的废水处理。 一、臭氧氧化+BAF工艺 1.1 工艺介绍 臭氧氧化法作为一种高级氧化工艺,在与BAF结合的组合工艺中,主要起到对低浓度、难降解有机污染物的开环断链以降低废水毒性、提高废水可生化性的作用。臭氧氧化与BAF 是相互依存的统一体,不同的臭氧投加量和氧化反应时间,会得到不同的氧化产物,驯养出不同的BAF生物菌群,从而影响出水水质,因此设计时二者应统一考虑。 工程上常见的臭氧氧化工艺分为臭氧接触氧化工艺和臭氧催化氧化工艺2种型式,臭氧接触氧化池、臭氧催化氧化池结构见图1。 臭氧接触氧化池、臭氧催化氧化池的区别主要在于院后者在臭氧氧化池中加入了附着于活性氧化铝等载体上的过渡金属催化剂,能有效降低20%~30%的臭氧投加量,缩短50%左右的反应时间。由于催化剂填料床的存在,SS过多易造成填料床堵塞,因此臭氧催化氧化池需要设置反洗设施,定期反洗。 BAF集生物氧化和截留悬浮物固体于一体,利用微生物的吸附、截留及降解功能去除废水中的有机污染物。BAF具有多种型式,本次研究的类型主要有普通陶粒滤料BAF、轻质滤料BAF和内循环BAF,其结构见图2。

轻质滤料BAF的滤料密度小于水,采用亲水性高分子材料加工而成,空间结构呈网状,比表面积大于1×105m2/m3,孔隙率大于85%,因此生物膜更易附着在滤料上、挂膜快、流失少,相比陶粒滤料,单位体积生物量更大、处理效果更好。内循环BAF采用多孔生物滤料,相比普通陶粒滤料,空隙率提高了15%,密度下降了20%,同时其独有的隔离式曝气技术,给反应器充氧的同时,将污水沿曝气器管道提升,再经过反应器生物床,在填料区形成循环水流。该生物反应器实现了曝气与生化的分离,其生物膜边界层厚度仅为普通陶粒滤料BAF的1/5,大幅度提高了生物膜相与水相间的传质速度,同时减少了曝气对生物膜的冲刷和气水短路沟流的产生。 1.2 工程实例 臭氧氧化+BAF的部分工程应用实例见表1。

《废水深度处理技术》课程教学大纲

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污水深度处理分级工艺划分

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化工污水处理设备整个过程为通过粗格栅的原污水经过污水提 升泵提升后,经过格栅或者筛率器,之后进入沉砂池,经过砂水分离的污水进入初次沉淀池,以上为一级处理(即物理处理),初沉池的出水进入生物处理设备,有活性污泥法和生物膜法,(其中活性污泥法的反应器有曝气池,氧化沟等,生物膜法包括生物滤池、生物转盘、生物接触氧化法和生物流化床),生物处理设备的出水进入二次沉淀池,二沉池的出水经过消毒排放或者进入三级处理,一级处理结束到此为二级处理,三级处理包括生物脱氮除磷法,混凝沉淀法,砂滤法,活性炭吸附法,离子交换法和电渗析法。二沉池的污泥一部分回流至初次沉淀池或者生物处理设备,一部分进入污泥浓缩池,之后进入污泥消化池,经过脱水和干燥设备后,污泥被最后利用。 经过三级污水深度处理处理后的,出水水质即可满足污水排放水质标准,如若想污水回用,则需再经过深度处理才能满足水质要求。

工业废水深度处理工艺

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污水处理厂出水深度处理方案模板

污水处理厂出水深度处理方案 一、概述 水是国民经济发展中的不可替代的重要资源, 也是人类赖以 生存和发展的重要资源。电厂又是耗水大户, 特别是在中国北方, 以水限电、以水定电的情况相当严重, 水资源的紧张已逐渐成为电力发展的瓶径, 如何节约用水, 提高水的利用率是电厂急需解决的问题。开展中水回用是解决这问题的重要途径, 也是大势所趋。在电力生产过程中, 冷却水的消耗占电厂总耗水量的60~80%, 因此, 城市污水处理厂二级处理出水( 中水) 深度处理后作为电厂冷却水补充水, 如能成功实施, 将起到良好的示范效应, 适应可持续发展 需要, 并为电力发展拓展空间, 具有巨大的经济、社会、环境效益。城市污水具有水量大、来源可靠、水量稳定的特点, 但水质复杂, 其中有机物、微生物和化学溶剂较多。因此, 城市污水二级生化出水要作为电厂循环冷却水, 必须先进行深度处理。使用城市污水做为冷却水的电厂, 其中多数采用石灰处理工艺, 一部分采用单纯过滤法, 一部分采用超滤技术。 石灰处理系统作为电厂循环冷却水的补充水处理早在50年代就有应用的实例。尽管石灰处理系统具有运行费用低, 不污染自然水体等优点, 但由于劳动环境差、劳动强度大、污染、堵塞等原因影响了石灰处理技术的发展。随着科技的发展, 人们环保意识的

不断增强, 经过科技人员的不断努力, 石灰处理系统得到了许多改进, 越来越多的电厂采用了石灰处理系统, 积累了许多宝贵的经验。因此我公司拟采用石灰处理工艺对中水进行处理, 处理出水用作电厂循环冷却水。 二、石灰处理的原理、特点及分析 2.1石灰处理原理 石灰处理是经过投加石灰乳控制出水pH为10.3~10.5, 进行下面三个反应, 产生大量各种形态的CaCO3结晶, 降低水中暂硬, 同时生成的结晶核心还能够对其它杂质起凝聚、吸附作用; 而且石灰乳引起的pH值的升高也为氨氮和磷酸盐的去除创造了条件。为了提高工艺的沉淀效果, 一般在处理过程中投加适量的凝聚剂与助凝剂, 经过压缩双电层作用使分散的悬浮物、CaCO3结晶、有机物、有机粘泥、胶体物等带电体脱稳, 在机械混合搅拌和高分子助凝剂架桥与网捕作用下, 颗粒物质碰撞结合长大, 使污染物容易沉降。 石灰参与的软化反应有: CO2+Ca(OH)2→CaCO3↓+H2O

污水的几种深度处理方法

目录 污水的几种深度处理方法 (2) 1.1 活性炭吸附法与离子交换 (2) 1.2 膜分离法 (2) 1.3.1 湿式氧化法 (3) 1.3.2 湿式催化氧化法 (3) 1.3.3 超临界水氧化法 (4) 1.3.4 光化学催化氧化法 (4) 1.3.5 电化学氧化法 (4) 1.3.6 超声辐射降解法 (5) 1.3.7 辐射法 (5) 1.4 臭氧法 (5) Ⅰ

污水的几种深度处理方法 污水深度处理,也称高级处理或三级处理。它是将二级处理出水再进一步进行物理、化学和生物处理,以便有效去除污水中各种不同性质的杂质,从而满足用户对水质的使用要求。深度处理常见的方法有以下几种。 1.1 活性炭吸附法与离子交换 活性炭是一种多孔性物质,而且易于自动控制,对水量、水质、水温变化适应性强,因此活性炭吸附法是一种具有广阔应用前景的污水深度处理技术。活性炭对分子量在500~3 000的有机物有十分明显的去除效果,去除率一般为70%~86.7%[1],可经济有效地去除嗅、色度、重金属、消毒副产物、氯化有机物、农药、放射性有机物等。 常用的活性炭主要有粉末活性炭(PAC)、颗粒活性炭(GAC)和生物活性碳(BAC)三大类。近年来,国外对PAC的研究较多,已经深入到对各种具体污染物的吸附能力的研究。淄博市引黄供水有限公司根据水污染的程度,在水处理系统中,投加粉末活性炭去除水中的COD,过滤后水的色度能降底1~2度;臭味降低到0度[2]。GAC在国外水处理中应用较多,处理效果也较稳定,美国环保署(USEPA)饮用水标准的64项有机物指标中,有51项将GAC列为最有效技术[3]。 GAC处理工艺的缺点是基建和运行费用较高,且容易产生亚硝酸盐等致癌物,突发性污染适应性差。如何进一步降低基建投资和运行费用,降低活性炭再生成本将成为今后的研究重点。BAC可以发挥生化和物化处理的协同作用,从而延长活性炭的工作周期,大大提高处理效率,改善出水水质。不足之处在于活性炭微孔极易被阻塞、进水水质的pH 适用范围窄、抗冲击负荷差等。目前,欧洲应用BAC技术的水厂已发展到70个以上,应用最广泛的是对水进行深度处理[4]。抚顺石化分公司石油三厂采用BAC技术,既节省了新鲜水的补充量,减少污水排放量,减轻水体污染,降低生产成本,还体现了经济效益和社会效益的统一[5]。今后的研究重点是降低投资成本和增加各种预处理措施与BAC联用,提高处理效果。 1.2 膜分离法 膜分离技术是以高分子分离膜为代表的一种新型的流体分离单元操作技术[6,7]。它的最大特点是分离过程中不伴随有相的变化,仅靠一定的压力作为驱动力就能获得很高的分离效果,是一种非常节省能源的分离技术。 微滤可以除去细菌、病毒和寄生生物等,还可以降低水中的磷酸盐含量。天津开发区污水处理厂采用微滤膜对SBR二级出水进行深度处理, 满足了景观、冲洗路面和冲厕等市政杂用和生活杂用的需求[8]。

制药废水深度处理技术

安峰环保 随着科学技术的发展,人们的日常需求和社会发展需求将得到更好的满足。对大多数制药企业来说,药品生产过程中的药物浓度过高,如果废水处理得不好,其中的有害物质会继续扩散。因此,在排放这些废水之前,必须深入处理这些废水,降低这些废水的危害。然而,目前医药废水的深度处理还存在许多问题,没有良好的处理效果。本文综合分析了医药废水的深度处理。 目前制药废水深度处理的主要技术 1、混凝沉淀技术 目前,混凝沉淀技术是我国废水处理中最常用的技术。该技术可深入处理制药废水。它可分为以下几个部分: 第一,化学药剂可以放在水中分散,可以将污水中的微小部分转化为不稳定的分离状态,整体污水可以团结和絮状存在。 其次,当污水中的物质形成絮凝体时,混凝技术可以继续发挥重力作用,从而减少污染物,最终可以有效分离固体和液体。混凝沉淀工艺在国内出现较早,因此相关设备相对齐全,操作流程相对简单。例如,在废水处理过程中,可以向内部投入120毫克/升的混凝剂。此时ph值为8,25s,去污率可达89%。总的来说,去污效率高。但是这种方法在溶解毒性方面不是很有效,而且很难从微生物中去除病原体。 2、膜分离技术 早在60年代和70年代,70年代。在使用过程中也会显示出质量的细化和浓缩,整个操作过程相对简单。不仅使整个运行过程变得更节能,而且可以更好地控制。在污水处理过程中,主要采用反渗透和微滤技术去除沉积物中的细菌杂质,有效地减少内部矿化。采用反渗透技术可以控制90%的脱盐率,水回收率可以控制在70%。一般来说,膜生物反应器能有效地将传统的污水处理技术与最新的污水处理技术相结合,从而对污水进行处理。在某制药厂污水处理过程中,发现溶解氧浓度和质量为8,出水化学需氧量和生化需氧量的去除率分别为93%和94%。但在实际运行过程中,发现技术投入过大,使得相关处理技术无法发挥更好的作用。 3、生物处理技术 目前的医药废水处理技术不能满足新的排放标准。但生物处理技术仍是最常用的处理方法。目前,生物处理技术不仅处理成本较低,而且效果更稳定。好氧生物处理技术可以中和废水中的有害物质。因此,在实际运行过程中,有必要将预处理技术与好氧深度处理技术有效结合。在污水深度处理的实际过程中,预处理技术和氧气生化处理技术应有效结合。

污水深度处理常见的方法

【tips】本文由李雪梅老师精心收编,值得借鉴。此处文字可以修改。 污水深度处理常见的方法 深度处理常见的方法有以下几种: 1 活性炭吸附法活性炭是一种多孔性物质,而且易于自动控制,对水量、水质、水温变化适应性强,因此活性炭吸附法是一种具有广阔应用前景的污水深度处理技术。活性炭对分子量在500~3 000的有机物有十分明显的去除效果,去除率一般为70%~86.7%,可经济有效地去除嗅、色度、重金属、消毒副产物、氯化有机物、农药、放射性有机物等。常用的活性炭主要有粉末活性炭(PAC)、颗粒活性炭(GAC)和生物活性碳(BAC)三大类。 近年来,国外对PAC的研究较多,已经深入到对各种具体污染物的吸附能力的研究。淄博市引黄供水有限公司根据水污染的程度,在水处理系统中,投加粉末活性炭去除水中的COD,过滤后水的色度能降底1~2度;臭味降低到0度。GAC在国外水处理中应用较多,处理效果也较稳定,美国环保署(USEPA)饮用水标准的64项有机物指标中,有51项将GAC列为最有效技术。 GAC处理工艺的缺点是基建和运行费用较高,且容易产生亚硝酸盐等致癌物,突发性污染适应性差。如何进一步降低基建投资和运行费用,降低活性炭再生成本将成为今后的研究重点。BAC可以发挥生化和物化处理的协同作用,从而延长活性炭的工作周期,大大提高处理效率,改善出水水质。不足之处在于活性炭微孔极易被阻塞、进水水质的pH 适用范围窄、抗冲击负荷差等。 目前,欧洲应用BAC技术的水厂已发展到70个以上,应用最广泛的是对水进行深度处理。抚顺石化分公司石油三厂采用BAC技术,既节省了新鲜水的补充量,减少污水排放量,减轻水体污染,降低生产成本,还体现了经

污水深度处理工艺

污水深度处理(sewage depth processing)是指城市污水或工业废水经一级、二级处理后,为了达到一定的回用水标准使污水作为水资源回用于生产或生活的进一步水处理过程。针对污水(废水)的原水水质和处理后的水质要求可进一步采用三级处理或多级处理工艺。常用于去除水中的微量COD和BOD有机污染物质,SS及氮、磷高浓度营养物质及盐类。 处理方法 深度处理的方法有:絮凝沉淀法、砂滤法、活性炭法、臭氧氧化法、膜分离法、离子交换法、电解处理、湿式氧化法、蒸发浓缩法等物理化学方法与生物脱氮、脱磷法等。深度处理方法费用昂贵,管理较复杂,除了每吨水的费用约为一级处理费用的4-5倍以上。 方法简介 1、活性炭吸附法活性炭是一种多孔性物质,而且易于自动控制,对水量、水质、水温变化适应性强,因此活性炭吸附法是一种具有广阔应用前景的污水深度处理技术。活性炭对分子量在500~3 000的有机物有十分明显的去除效果,去除率一般为70%~86.7%,可经济有效地去除嗅、色度、重金属、消毒副产物、氯化有机物、农药、放射性有机物等。常用的活性炭主要有粉末活性炭(PAC)、颗粒活性炭(GAC)和生物活性碳(BAC)三大类。近年来,国外对PAC的研究较多,已经深入到对各种具体污染物的吸附能力的研究。淄博市引黄供水有限公司根据水污染的程度,在水处理系统中,投加粉末活性炭去除水中的COD,过滤后水的色度能降底1~2度;臭味降低到0度。GAC在国外水处理中应用较多,处理效果也较稳定,美国环保署(USEPA)饮用水标准的64项有机物指标中,有51项将GAC列为最有效技术。 GAC处理工艺的缺点是基建和运行费用较高,且容易产生亚硝酸盐等致癌物,突发性污染适应性差。如何进一步降低基建投资和运行费用,降低活性炭再生成本将成为今后的研究重点。BAC可以发挥生化和物化处理的协同作用,从而延长活性炭的工作周期,大大提高处理效率,改善出水水质。不足之处在于活性炭微孔极易被阻塞、进水水质的pH 适用范围窄、抗冲击负荷差等。目前,欧洲应用BAC技术的水厂已发展到70个以上,应用最广泛的是对水进行深度处理。抚顺石化分公司石油三厂采用BAC技术,既节省了新鲜水的补充量,减少污水排放量,减轻水体污染,降低生产成本,还体现了经济效益和社会效益的统一。今后的研究重点是降低投资成本和增加各种预处理措施与BAC联用,提高处理效果。 2、膜分离法膜分离技术是以高分子分离膜为代表的一种新型的流体分离单元操作技术。它的最大特点是分离过程中不伴随有相的变化,仅靠一定的压力作为驱动力就能获得很高的分离效果,是一种非常节省能源的分离技术。微滤可以除去细菌、病毒和寄生生物等,还可以降低水中的磷酸盐含量。天津开发区污水处理厂采用微滤膜对SBR二级出水进行深度处理, 满足了景观、冲洗路面和冲厕等市政杂用和生活杂用的需求。超滤用于去除大分子,对二级出水的COD和BOD去除率大于50%。北京市高碑店污水处理厂采用超滤法对二级出水进行深度处理,产水水质达到生活杂用水标准,回用污水用于洗车,每年可节约用水4700 m3。反渗透用于降低矿化度和去除总溶解固体,对二级出水的脱盐率达到90%以上,COD和BOD 的去除率在85%左右,细菌去除率90%以上。缅甸某电厂采用反渗透膜和电除盐联用技术,用于锅炉补给水。经反渗透处理的水,能去除绝大部分的无机盐、有机物和微生物。纳滤介于反渗透和超滤之间,其操作压力通常为0.5~1.0 MPa,纳滤膜的一个显著特点是具有离子选择性,它对二价离子的去除率高达95%以上,一价离子的去除率较低,为40%~80%。采用膜生物反应器-纳滤膜集成技术处理糖蜜制酒精废水取得了较好结果,出水COD小于100 mg/L,废水回用率大于80%。我国的膜技术在深度处理领域的应用与世界先进水平尚有较大差距。今后的研究重点是开发、制造高强度、长寿命、抗污染、高通量的膜材料,着重解决膜污染、浓差极化及清洗等关键问题。 3、高级氧化法工业生产中排放的高浓度有机污染物和有毒有害污染物,种类多、危害大,

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百度文库- 让每个人平等地提升自我 《工业废水深度处理与回用技术评估导则》 (征求意见稿) 编制说明 编制单位:轻工业环境保护研究所 二〇一二年四月

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