Research Article Polychlorinated Biphenyls in the ...

Research ArticlePolychlorinated Biphenyls in the CentralizedWastewater Treatment Plant in a Chemical Industry ZoneSource Distribution and Removal

Min Yao12 Zhongjian Li1 Xingwang Zhang1 and Lecheng Lei1

1 Key Laboratory of Biomass Chemical Engineering of Ministry of Education Zhejiang University Hangzhou 310027 China2 Faculty of Architectural Civil Engineering and Environment College Ningbo University Ningbo 315211 China

Correspondence should be addressed to Lecheng Lei lcleizjueducn

Received 13 March 2014 Revised 8 June 2014 Accepted 10 July 2014 Published 5 August 2014

Academic Editor Davide Vione

Copyright copy 2014 Min Yao et alThis is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Polychlorinated biphenyls (PCBs) could be dissolved in wastewater or adsorbed on particulate The fate of PCBs in wastewateris essential to evaluate the feasibility of wastewater treatment processes and the environmental risk Here dissolved and adsorbedconcentrations of twenty concerned PCB congeners and total PCBs have been measured in the centralized wastewater treatmentplant of a chemical industry zone in Zhejiang China It was found that the dyeing chemical processes were the main source ofPCBs which contributed more than 136 The most abundant PCB was PCB-11 in the liquid and solid phase of each treatmentstage accounting for more than 60 of the total 209 PCBs Partitioning behavior of PCBs between the dissolved and adsorbedphases suggested that Di-CBs were the dominant isomers (gt70) and more than 898 of them was adsorbed on the particles andsludge The total removal efficiency of sum209 PCBs was only 232 throughout the whole treatment process A weak correlationwas obtained between the individual PCB concentration and their log119870ow in primary sedimentation anaerobic hydrolysis aerobicbioprocess stage and the whole treatment process

1 Introduction

Polychlorinated biphenyls (PCBs) are a class of significantpersistent organic pollutants (POPs) that consist of 209congeners being of increasing global concern because oftheir high toxicity resistance to biodegradation biologicalaccumulation and long-range transport [1] Although PCBsproduction in most countries has been banned since the1970s and 1980s PCBs contaminations remain ubiquitousand coexist in most environmental matrices including watersediment soil and air all over the world [2ndash4] Exposureto PCBs can cause neurological disorder reproductive tox-icity endocrine disruption cancer and deformity even atextremely low concentrations [5] Thus it is important andnecessary to study the source distribution and removal ofPCBs in the environment

There are various sources of existing PCBs in the envi-ronment most of which were accumulated during the period1950 to 1983 due to their worldwide use as lubricants

heat transfer agents paint additives and insulating mediain capacitors and voltage regulations Also PCBs can begenerated and introduced into the environment as byprod-ucts from waste incineration and various chemical industrialprocesses [6] Therefore tracing the source of PCBs is veryimportant to study their transport and fate in the environ-ment [7] Recently it is reported that the wastewater treat-ment plants (WWTPs) are another potential source of PCBsto the ambient environment [6 8ndash11] Therefore increasingattention has been paid to the fate of PCBs in WWTPsKatsoyiannis and Samara [12] found that more than 50 ofthe total seven indicator PCB congeners (PCB-28 52 101 118138 153 and 180) were absorbed in sludge and the concen-tration of the PCBs in wastewater was decreased from 1000to 250 ngL after treatment (samples were from a WWTPin Thessaloniki northern Greece) However Bergqvist etal [10] found that the concentrations of sumPCBs (sevenindicator PCBs and PCB-47 105 156) increased from 03 to1 ngL in Umea (Sweden) and from 9 to 34 ngL in Siauliai

Hindawi Publishing CorporationJournal of ChemistryVolume 2014 Article ID 352675 10 pageshttpdxdoiorg1011552014352675

2 Journal of Chemistry

Aerobic bioprocessAnaerobic hydrolysis

Waste activated sludge

Retu

rned

Activ

ated

slud

ge

SSE

Lift pump

PSS

ASHCS

HCE

Sludge thickener

Outgoing wastewater

Mixing regulation

Incoming sewer

High-density clarifier

RWPSE AHE

Belt filter

Disposal

FS

Primary sedimentation

Secondary sedimentation

Figure 1 Flow chart of the centralized WWTP in Zhejiang China (f location of samplings) RW raw wastewater PSE primarysedimentation effluent AHE anaerobic hydrolysis effluent SSE secondary sedimentation effluent HCE high-density clarifier effluent PSSprimary sedimentation sludge AS activated sludge HCS high-density clarifier sludge and FS final sludge

(Lithuania) WWTP during the treatment process Based onthe above-mentioned two papers it is very likely that differentwastewater components and wastewater treatment processeshave significant effect on the PCBs fate In China owingto the rapid development in manufacturing industries thepollutants in wastewater are increasing dramatically whichincreased the variety and complexity of PCBs in wastewaterin WWTPs However few detail data are available for thefate and removal of PCBs in the WWTPs in China takingboth PCBs distribution inwater and absorption in sludge intoaccount

The aim of our study was to thoroughly investigatethe fate of PCBs in the conventional wastewater treatmentprocesses Here a WWTP treating dyeing chemicals anddomestic wastewater in Zhejiang province China was cho-sen in this project Firstly we investigated the PCBs in theWWTP contributed by the dyeing chemical industry Thenthe indicator PCBs dioxin-like PCB congeners and threelightly chlorinated biphenyls (PCB-11 15 19) and total PCBs(from Mono-CBs to Deca-CBs) were quantitatively analyzedboth in wastewater and sludge at each treatment stage in theWWTP The distribution of PCBs between the dissolved andadsorbed phases in the influent and effluent of each treatmentstage was investigated as well Furthermore PCBs removalefficiencies at each treatment stage and the key removalmechanismwere also studied Ourworkwill provide a deeperunderstanding of the PCBs fate in WWTP and a theoreticalbasis for the source control

2 Materials and Methods

21 Plant Description and Sampling

211 Plant Description The centralized wastewater treat-ment plant (WWTP) is located in a chemical industry zone

in Zhejiang province ChinaTheWWTP is located outdoorsand processes 90000ndash120000m3 of raw wastewater per dayAbout 70 of the total flow is contributed by industrialactivities especially by dyeing chemical industries in thezone as well as a small amount of domestic sewage Theinfluents of wastewater through pipelines first pass screeningand grit and grease chambers and then are fully mixed inthe mixing regulation tank to be the raw wastewater (iemixed influent) The wastewater treatment processes includeprimary sedimentation using chemical flocculants (polyalu-minumchloride PAC) anaerobicaerobic (AO) biochemicaltreatment (including anaerobic hydrolysis process by anaer-obic biofilter and aerobic bioprocess by activated sludge)secondary sedimentation for the settlement of activatedsludge and high-density clarifier by ferrate oxidation Theflow chart of the plant is shown in Figure 1

212 Sampling Sites The wastewater suspended particulatematter (SPM) and sludge samples were taken from theoutlet of each processing stage during late October and earlyNovember 2010 (October 26 and November 6) Duplicatesamples of wastewater were collected along the treatmentsystem to study the sampling reproducibility namely themixed influent of raw wastewater in the mixing regulationtank (RW) the effluents of primary sedimentation anaerobichydrolysis aerobic bioprocess secondary sedimentation andhigh-density clarifier tanks (PSE AHE SSE and HCEresp) Grab samples of sludge were collected from theprimary sedimentation tank (PS) the recirculation stream(activated sludge AS) high-density clarifier tank (HCS) andsludge thickener tank (final sludge FS) concurrently withthe wastewater samples All sampling containers were insequence washed with water acetone dichloromethane andthe wastewater samples before use

Journal of Chemistry 3

Furthermore in order to estimate the industrial sourcesof PCBs two wastewater samples were collected from thelargest dyeing chemical group in this zone whichmainly pro-duced disperse reactive acid vat dyestuff or pigments andintermediates One sample was the mother liquor producedduring the pigment synthesis process and the other was thetreated effluent of the mother liquor entering the WWTPThe amounts of wastewater discharged into the WWTP wereabout 8000m3 per day

22 Chemicals and Reagents All solvents including acetonen-hexane methanol and dichloromethane were of HPLCgrade and purchased from Tedia Co USA Water waspurified with an ultrapure water system (Purelab UHQ ElgaLabWater UK) Silica gel (100ndash200 mesh reagent gradeQingdao Ocean Chemical Reagent Co China) anhydroussodium sulfate (analytical grade Chongqing Kelong Chem-ical Reagent Co China) and glass fiber filters (045 120583meffective pore sizes ShanghaiMosu Scientific Equipment CoChina) were baked in a furnace oven at 450∘C for 4 h prior touse

PCB calibration standard solutions 13C-labeled surrogatestandards (13C-PCB-14 65 and 166) and injection standards(13C-PCB-9 52 101 138 and 194) complying with US EPAmethod 1668A for PCBs analysis were purchased fromCambridge Isotope Laboratories in USA Here the mainlyconcerned PCBs were 20 individual PCB congeners and totalPCBs (from Mono-CBs to Deca-CBs) The individual con-geners included six indicator congeners (PCB-28 52 101 118138 153 and 180) ten dioxin-like PCB (PCB-77 81 105 114123 126 156 167 169 and 189) and three lightly chlorinatedbiphenyls (PCB-11 15 and 19) respectively The workingstandard solutions were prepared by diluting appropriatevolumes of the standard PCB mixture with HPLC-grade n-hexane

23 Sample Extraction and Purification 1 L of wastewatersamples was filtered using glass fiber filter and spiked with200 ng of 13C-labeled surrogate standards and then extractedthree times under ultrasonic conditions using liquid-liquidextraction method The total extracted volume was 180mLof dichloromethanehexane (1 1 vv) and the extracts wereconcentrated to 2mL and subjected to a solvent exchange tohexane by a rotary evaporator (RE-52AA Yarong ShanghaiChina) The concentrated extracts were sequentially subjectto multilayer silica gel basic alumina and florisil chromatog-raphy columns for further cleanup following the publishedprocedures [9 13ndash15] The multilayered silica gel column wasself-made column which was packed from bottom to topwith 1 g of activated silica 4 g of basic silica (12 ww)1 g of activated silica 8 g of acid silica (30 ww) 2 g ofactivated silica and 4 g of anhydrous sodium sulfate Thecolumns were preserved in dichloromethanehexane (1 1vv) before loading the extracts Elution of the samples wascarried out at a rate of 1mLmin under vacuum with 5dichloromethanehexane (vv)Then the eluent was collectedand evaporated to near dryness with rotary evaporatorHexane solvent was introduced as a replacement and then

concentrated to 20120583L with gentle stream of nitrogen Then13C-labeled internal standards were added prior to the GCinjection for quantitative analysis All samples were analyzedin duplicate and the average concentrations (means plusmn SD119899 = 2) were reported

The SPM in the wastewater was separated by glass fiberfilters and the sludge was dehydrated by centrifugationThe filters and sludge were freeze dried until constantweights were maintained Solid samples were accuratelyweighted and spiked with 1 ng of 13C-labeled surrogatestandards and then Soxhlet-extracted for 24 h with 400mLof dichloromethaneacetone (1 1 vv)The extracts were con-centrated to about 5mL and subjected to a solvent exchangeto hexane The concentrated extracts were subsequentlypurified and fractionated following the above mentionedmethod under identical conditions [16]

24 GCMS Analysis and Quality Control PCBs were ana-lyzed by isotope dilution method and the analysis procedurewas similar to the method described by Yang et al [15]The quantification of PCBs extracts in the wastewater SPMand sludge samples was performed on an Agilent 6890Agas chromatograph (GC) coupled with 5795C inert massspectrometer (MS) detector (Agilent Technologies USA)with an electron impact (EI) ion sourceTheMSwas operatedin selective ion monitoring (SIM) mode Helium was used ascarrier gaswith flow rate of 12mLmin Exactly 1120583Lof extractsolution was injected with 16-sample autoinjector in splitlessmode into a DB-5MS capillary column (60m times 025mm idtimes 025 120583m film thickness JampW Scientific USA) The injectortemperature and source temperature were 280 and 250∘Crespectively The oven temperature program was as follows110∘C held for 3min 110ndash150∘C at 10∘Cmin 150ndash270∘C at25∘Cmin held for 5min and 270ndash320∘C at 25∘Cmin heldfor 10min

The blank blank spike and parallel samples were intro-duced for quality assurance and quality control The back-ground concentrations were negligible due to their signifi-cantly lower levels compared to actual samples (lt3) Recov-eries of added 13C-labeled PCB-14 PCB-65 and PCB-166surrogate standards to wastewater samples prior to extractionaveraged 84 plusmn 6 88 plusmn 6 and 94 plusmn 4 respectivelyRecoveries of added 13C-PCB-14 PCB-65 and PCB-166 toSPM and sludge samples prior to extraction averaged 68 plusmn15 72 plusmn 15 and 88 plusmn 10 respectively The recoveriesmeet the requirements of US EPA method 1668A [14]

3 Results and Discussion

31 Source Analysis of PCBs from Dyeing Chemical IndustryEntering the WWTP PCBs entering the centralized WWTPcan be mainly associated with direct discharges from indus-trial emissions in the investigated zone In order to identifythe main industrial emissions as PCB source to the WWTPwe investigated the profiles of the factories or companies inthe investigated zoneThis zone is a professional developmentzone featuring as fine chemical industry focusing on pro-ducing of pharmaceuticals and the intermediates pigments


and dyes textile dyeing and finishing biochemical inorganicchemicals and other specialty chemicals The wastewaterproduced during the chemical processes was discharged intothe WWTP after simple treatment In this zone the wastew-ater discharged by pigment and dyeing chemical industriesaccounts for about 70 of the total industrial wastewaterData provided by US EPA and other workers indicate thatPCBs have been found in various color dyestuff and pigments[3 17ndash19] Rodenburg and colleagues knewPCB-11 was linkedto the manufacture of diarylide yellow pigments [3] Hu andHornbuckle detected more than 50 PCB congeners in azoand phthalocyanine pigments [18] Litten et al also foundhigh levels of PCBs in wastewater in New York harbor andtraced them to effluent from a pigment manufacturing plant[17] Thus we mainly detected the PCBs in dyeing chemicalwastewater discharged by the largest chemical industrialgroup and identified the contribution of PCBs to theWWTPby the group

The PCB species and concentrations in wastewaterdepend on the raw materials and the process of dyestuffor pigments production It is investigated that the dyeingchemical industrial groupmainly produces disperse reactivevat pigments and some intermediates which are mainly azopigments with polycyclic ketone structures and producedthrough a reaction sequence of diazotization (coupling toafford the azo group ndashN=Nndash) condensation close-loopchlorination oxidation and reduction and so forth [20]During the synthesis of these productions there are variousderivatives of polycyclic hydrocarbons used as the precursorssuch as alkylbenzenes naphthol anthrone anthraquinoneacenaphthene and quinone [21] Therefore with high tem-perature and humidity in the dye synthesis processes it is easyto generate PCBs and other POPs byproducts Based on theconcentrations and water quantity the average contributionof each PCB congener was calculated and listed in Table 1 It isshown that lightly chlorinated biphenyls were the main PCBspecies and PCB-11 77 28 and 15 were the most abundantcongeners produced during the dyemanufacturing processesThe contribution of sum209 PCBs produced by this dyeingchemical industrial group to theWWTPwas 136The threegreatest contributors wereDi-CBs Hexa-CBs andNona-CBswith the contribution percent of 154 152 and 116respectively

32 PCBConcentrations inWastewater Samples of theWWTPThe results of PCB concentrations in wastewater samplesin the influent and effluent of each WWTP treatment stageare presented in Table 2 As shown the concerned 20 PCBcongeners and PCB isomers were detectable in the RWsamples The most abundant PCB entering the WWTP inRW was PCB-11 with mean concentration of 103216 pgLaccounting for 661 of the total 209 PCBsThe less abundantPCBs were still the lightly chlorinated biphenyls includingPCB-15 two indicator PCB congeners (PCB-52 and PCB-28) and one dioxin-like PCB congener (PCB-77) with meanconcentrations of 2416 2491 1735 and 1144 pgL respec-tivelyThe concentrations of total 209 PCBs were two or threeorders of magnitude lower than the ones observed in the

previous studies [12 22 23] which indicated the risk causedby dissolved PCBs was relatively low around the WWTPCompared with the data in the literature of Vogelsang et al[24] the concentration of indicator PCBs was three times asours

In PSE AHE SSE and HCE samples the presence ofmost PCB congeners was in general similar to that in RWsamples with PCB-11 being the most abundant compoundand PCB-15 PCB-28 PCB-52 and PCB-77 being the lessabundant compounds PCB-126 PCB-169 and PCB-189 werenot detected in the effluent samples of each treatment stagealthough found in RW PCB-81 and PCB-180 were notdetected in HCE samples Interestingly sum209 PCBs meanconcentration in AHE samples was higher than that in PSEsamples In detail the concentration of PCB-28 PCB-52 andPCB-77 in AHE samples suddenly increased by 270 357and 523 respectively In anaerobic hydrolysis stage theanaerobic microbes or anaerobic sludge always stay in theanaerobic fluidized bed without replacementThus the PCBsresults may be associated with the role of anaerobic microbesand the release of PCBs from solid to liquid phase

33 PCB Concentrations in SPM and Sludge Samples of theWWTP Table 3 summarizes the mean concentrations (nggdry weight) of the 20 PCB congeners and PCB isomers inthe SPM and sludge samples Here five PCB congeners werenot detected in the SPM of raw wastewater that is PCB-15PCB-19 and three dioxin-like PCBs (PCB-126 PCB-156 andPCB-169) All the 20 PCBs were detectable in the solid-phasesamples taken from following stage As seen in Tables 2 and3 the levels of PCB congeners in the solid phase were closelyrelated to the liquid concentrations in the influentThe higherconcentrations of PCBs in the influent the higher levels inSPM and sludge samples from effluent For example PCB-11was themost abundant PCBs both in liquid and in solid phasewith a high proportion of more than 60

In primary sedimentation stage the concentrations oftotal PCBs were nearly 2 times that in SPMof rawwastewaterdue to adsorption and sedimentation by PAC flocculantsHigh levels of PCBs were detected in anaerobic SPM andaerobic activated sludge indicating that the microbial sludgehad a strong biosorption and bioaccumulation for PCBswhichmade the contribution of biotransformation biodegra-dation and volatilization obscure Therefore sorption ofPCBs onto sludge was the most likely removal mechanismin the primary and biochemical treatment stages In high-density clarifier stage PCBs concentrations in effluent andsludge samples decreased more significantly than the ones inthe aerobic bioprocess stage owing to the oxidation (althoughno evidence is available in the literature of ferrate reactionwith PCBs) or the coagulation by ferrate because ferrateat pH lt 7 generates Fe(III) ions with excellent flocculationcapability and Fe(OH)

3that is a good adsorbent [25]

The mean concentrations of PCBs in the final sludgeof the centralized WWTP were also within the range ofreported values in Table 3 sum209 PCBs mean concentration(64323 ngg dw) was one or two orders of magnitude higherthan the values observed in previous studies reported by


Table 1 The concentrations (means plusmn SD) and contribution of PCBs discharged by the largest dyeing chemical industrial group entering theWWTP

PCBs (pgL) Mother liquor ofmanufacture

Treated mother liquor(entering the WWTP)

Raw wastewater inthe WWTP

Contribution rate to theWWTP by the group ()

Indicator PCB congenerPCB-28 34828 plusmn 7641 2423 plusmn 962 1735 plusmn 764 112PCB-52 16274 plusmn 461 1807 plusmn 459 2491 plusmn 325 58PCB-101 65 plusmn 27 41 plusmn 28 53 plusmn 18 62PCB-118 9626 plusmn 303 268 plusmn 144 487 plusmn 226 44PCB-138 6118 plusmn 185 1779 plusmn 467 615 plusmn 212 231PCB-153 8562 plusmn 264 2032 plusmn 354 89 plusmn 254 183PCB-180 878 plusmn 37 ND 31 plusmn 08 mdashSum indicator PCBs 39039 plusmn 6808 835 plusmn 2414 6302 plusmn 649 107

Dioxin-like PCB congenerPCB-77 589746 plusmn 10041 2129 plusmn 636 1144 plusmn 422 149PCB-81 27 plusmn 085 026 plusmn 02 013 plusmn 01 160PCB-105 1532 plusmn 68 81 plusmn 28 186 plusmn 71 35PCB-114 57 plusmn 34 08 plusmn 014 045 plusmn 01 142PCB-123 111 plusmn 64 44 plusmn 14 79 plusmn 14 45PCB-126 204 plusmn 24 15 plusmn 14 19 plusmn 14 63PCB-156 5 plusmn 61 87 plusmn 28 48 plusmn 14 145PCB-167 184 plusmn 172 13 plusmn 56 138 plusmn 42 75PCB-169 906 plusmn 52 06 plusmn 06 035 plusmn 03 137PCB-189 168 plusmn 14 19 plusmn 20 04 plusmn 03 380Sum DL-PCBs 59685 plusmn 9953 2522 plusmn 58 1627 plusmn 333 124

Other PCB congenerPCB-11 248702 plusmn 14707 182107 plusmn 7636 103216 plusmn 763 141PCB-15 13988 plusmn 2404 6075 plusmn 233 2416 plusmn 848 201PCB-19 2556 plusmn 170 94 plusmn 99 71 plusmn 71 106Mono-CBs 96215 plusmn 46103 8924 plusmn 240 8314 plusmn 848 86Di-CBs 325996 plusmn 20265 23518 plusmn 9758 1223310 plusmn 1004 154Tri-CBs 690054 plusmn 15174 4675 plusmn 125 63660 plusmn 169 59Tetra-CBs 2041154 plusmn 10449 6279 plusmn 132 95750 plusmn 141 52Penta-CBs 34426 plusmn 1188 842 plusmn 325 20250 plusmn 848 33Hexa-CBs 67142 plusmn 1386 6518 plusmn 778 34210 plusmn 113 152Hepta-CBs 787 plusmn 149 1714 plusmn 297 22130 plusmn 212 62Octa-CBs 21916 plusmn 222 752 plusmn 325 12560 plusmn 212 48Nona-CBs 6708 plusmn 328 58 plusmn 198 4010 plusmn 325 116Deca-CBs 2522 plusmn 184 133 plusmn 85 27 plusmn 184 39sum209 PCBs 7093902 plusmn 15635 265597 plusmn 9123 156172 plusmn 1691 136Flow rate of the treated mother liquor 8000m3d flow rate of raw wastewater in the WWTP 100000m3d ND not detected

Blanchard et al Guo et al and Katsoyiannis and Samara[12 16 22] According to the Chinese regulated law (GB18918-2002) PCB levels should be less than 200 ngg dw foragricultural use [26]Therefore the PCB levels in theWWTPsludge hereweremuchhigher than themaximumpermissibleconcentration andwere not suitable for agricultural purposes

34 Phase Distribution of PCBs in Wastewater and Sludgeof the WWTP The distribution of single compounds variedamong different systems whichmight be attributed to severalfactors such as the solute concentration the amount of

solids available for sorption and the competition betweenpollutants for sorption sites of the particles [7 27] Seenfrom Figure 2 Di-CBs (783ndash931) were the predominantisomers in wastewater samples followed by Tri-CBs (29ndash79) and Tetra-CBs (22ndash59) The proportion of otherhighly chlorinated biphenyls (Hexa-CBs to Deca-CBs) wasless than 5 in each stage effluent Similar to the profilesof PCB isomers in wastewater Di-CBs (704ndash840) werethe dominant isomers in sludge followed by Mono-CBs(79ndash152) and Tri-CBs (54ndash168) with less than 3 ofcontribution of other PCBs isomers


Table 2 The concentrations (means plusmn SD) of PCBs in wastewater of each treatment stage at the WWTP

PCBs (pgL) RW PSE AHE SSE HCEIndicator PCB congener

PCB-28 1735 plusmn 764 1632 plusmn 636 6033 plusmn 566 2374 plusmn 608 939 plusmn 495PCB-52 2491 plusmn 325 1312 plusmn 325 1781 plusmn 283 543 plusmn 254 316 plusmn 212PCB-101 53 plusmn 18 53 plusmn 17 21 plusmn 14 16 plusmn 14 11 plusmn 07PCB-118 487 plusmn 226 247 plusmn 85 296 plusmn 71 81 plusmn 56 6 plusmn 42PCB-138 615 plusmn 212 345 plusmn 141 184 plusmn 72 107 plusmn 71 61 plusmn 42PCB-153 89 plusmn 254 558 plusmn 221 39 plusmn 141 129 plusmn 85 86 plusmn 34PCB-180 31 plusmn 08 2 plusmn 14 25 plusmn 14 23 plusmn 14 NDSum indicator PCBs 6302 plusmn 649 4167 plusmn 356 873 plusmn 396 3273 plusmn 792 1473 plusmn 757

Dioxin-like PCB congenerPCB-77 1144 plusmn 422 937 plusmn 339 1427 plusmn 325 522 plusmn 283 88 plusmn 56PCB-81 013 plusmn 01 41 plusmn 14 39 plusmn 16 ND NDPCB-105 186 plusmn 71 109 plusmn 56 133 plusmn 42 3 plusmn 28 17 plusmn 14PCB-114 045 plusmn 01 31 plusmn 13 22 plusmn 13 17 plusmn 14 14 plusmn 14PCB-123 79 plusmn 14 29 plusmn 14 47 plusmn 14 39 plusmn 14 13 plusmn 14PCB-126 19 plusmn 14 ND ND ND NDPCB-156 48 plusmn 14 48 plusmn 11 71 plusmn 25 15 plusmn 14 13 plusmn 12PCB-167 138 plusmn 42 73 plusmn 42 64 plusmn 18 61 plusmn 28 11 plusmn 07PCB-169 035 plusmn 03 ND ND ND NDPCB-189 04 plusmn 03 ND ND ND NDSum DL-PCBs 1627 plusmn 333 1268 plusmn 294 1803 plusmn 290 684 plusmn 269 156 plusmn 35

Other PCB congenerPCB-11 103216 plusmn 763 101914 plusmn 552 9931 plusmn 495 99443 plusmn 424 94791 plusmn 424PCB-15 2416 plusmn 848 105 plusmn 51 765 plusmn 424 312 plusmn 354 103 plusmn 85PCB-19 71 plusmn 71 49 plusmn 42 46 plusmn 28 42 plusmn 28 32 plusmn 28Mono-CBs 8314 plusmn 848 6427 plusmn 636 5124 plusmn 707 875 plusmn 707 436 plusmn 354Di-CBs 1223310 plusmn 1004 121864 plusmn 992 118042 plusmn 735 114264 plusmn 665 111609 plusmn 566Tri-CBs 63660 plusmn 169 4253 plusmn 127 11822 plusmn 282 7079 plusmn 254 3486 plusmn 212Tetra-CBs 95750 plusmn 141 5543 plusmn 141 8795 plusmn 141 3029 plusmn 127 2613 plusmn 107Penta-CBs 20250 plusmn 848 1589 plusmn 735 1244 plusmn 735 741 plusmn 735 368 plusmn 313Hexa-CBs 34210 plusmn 113 1974 plusmn 113 1527 plusmn 113 549 plusmn 283 271 plusmn 226Hepta-CBs 22130 plusmn 212 1214 plusmn 212 1073 plusmn 212 673 plusmn 481 324 plusmn 325Octa-CBs 12560 plusmn 212 1919 plusmn 99 1657 plusmn 848 896 plusmn 707 376 plusmn 212Nona-CBs 4010 plusmn 325 461 plusmn 226 441 plusmn 198 583 plusmn 198 318 plusmn 141Deca-CBs 27 plusmn 184 165 plusmn 113 195 plusmn 85 168 plusmn 85 82 plusmn 85sum209 PCBs 156172 plusmn 1691 145409 plusmn 1397 14992 plusmn 618 128857 plusmn 659 119883 plusmn 510SS (mgL) 450 120 100 30 12RW raw wastewater (mixing influent) PSE primary sedimentation effluent AHE anaerobic hydrolysis effluent SSE secondary sedimentation effluent HCEhigh-density clarifier effluent and ND not detected

The partitioning behaviors of organic chemicals areessential to their fate in the WWTP as dissolved andadsorbed phases are differently available to different fateprocesses [11] Based on the PCBs concentrations in liquid-solid phase water quantity and SPM yield the relativedistribution of PCB isomers between the dissolved andadsorbed phases was obtained in the present study Figure 3presents the proportions of adsorbed PCB isomers in theinfluent and effluents of each treatment stage It is clearthat the adsorbed fraction of sum209 PCBs was found torange from 898 to 974 in the influent and effluent ofeach treatment stage much higher than the findings of

Katsoyiannis and Samara [28] with less than 60 of adsorbedsumPCBs in the influent ofWWTP inThessaloniki GreeceTheadsorbed PCB isomers in secondary sedimentation effluentwere absolutely predominant varying between 873 forOcta-CBs and 998 for Mono-CBs Likewise significantadsorbed fractions of PCB isomers were also found in the rawwastewater primary sedimentation effluent and anaerobichydrolysis effluent varying between 534 for Nona-CBs and991 for Tri-CBs 540 for Nona-CBs and 994 for Tri-CBs and 459 for Nona-CBs and 983 for Mono-CBsrespectively Differently in high-density clarifier effluentNona-CBs and Deca-CBs were more ldquodissolvedrdquo among


Table 3 The concentrations (means plusmn SD) of PCBs in SPM and sludge of each treatment stage at the WWTP

PCBs(ngg dw)

SPM in RW PSS SPM in AHE AS HCS FS

Indicator PCB congenerPCB-28 1005 plusmn 212 2666 plusmn 636 3167 plusmn 82 2558 plusmn 891 8736 plusmn 325 13171 plusmn 158PCB-52 6289 plusmn 283 173 plusmn 71 1975 plusmn 707 2241 plusmn 990 785 plusmn 174 264 plusmn 151PCB-101 0139 plusmn 004 0357 plusmn 004 0437 plusmn 007 0377 plusmn 009 1 plusmn 0042 3101 plusmn 017PCB-118 0416 plusmn 007 117 plusmn 008 1365 plusmn 011 1665 plusmn 014 0204 plusmn 008 2763 plusmn 029PCB-138 0243 plusmn 005 0698 plusmn 006 0869 plusmn 014 0903 plusmn 032 029 plusmn 006 3002 plusmn 051PCB-153 0394 plusmn 006 1013 plusmn 007 1362 plusmn 031 1829 plusmn 049 0307 plusmn 007 2893 plusmn 073PCB-180 0032 plusmn 001 0063 plusmn 003 0087 plusmn 007 0108 plusmn 012 0033 plusmn 003 0282 plusmn 020Sum Ind 1080 plusmn 185 2872 plusmn 567 3405 plusmn 898 2831 plusmn 100 9705 plusmn 345 13556 plusmn 175

Dioxin-like PCB congenerPCB-77 4835 plusmn 057 1284 plusmn 622 1481 plusmn 714 1502 plusmn 863 485 plusmn 202 2015 plusmn 138PCB-81 0027 plusmn 001 0043 plusmn 003 0057 plusmn 004 0064 plusmn 006 002 plusmn 001 0119 plusmn 009PCB-105 0137 plusmn 003 0404 plusmn 005 0463 plusmn 007 0519 plusmn 009 0119 plusmn 005 1345 plusmn 018PCB-114 001 plusmn 0004 31 plusmn 13 0026 plusmn 001 0076 plusmn 004 0015 plusmn 001 0112 plusmn 008PCB-123 0002 plusmn 0001 29 plusmn 14 0014 plusmn 001 008 plusmn 001 0064 plusmn 0004 0368 plusmn 019PCB-126 ND ND 0012 plusmn 001 0033 plusmn 003 0012 plusmn 0001 0242 plusmn 004PCB-156 ND 48 plusmn 11 0014 plusmn 001 0095 plusmn 004 0026 plusmn 0001 0859 plusmn 006PCB-167 0204 plusmn 0006 73 plusmn 42 0643 plusmn 005 0496 plusmn 006 0352 plusmn 002 0648 plusmn 011PCB-169 ND ND 0042 plusmn 002 0086 plusmn 004 0025 plusmn 0034 0103 plusmn 010PCB-189 0038 plusmn 0008 ND 0101 plusmn 006 0173 plusmn 009 0105 plusmn 0047 0257 plusmn 018Sum DL 5254 plusmn 055 1268 plusmn 294 1619 plusmn 744 1664 plusmn 883 559 plusmn 2207 242 plusmn 147

Other PCB congenerPCB-11 80323 plusmn 212 101914 plusmn 552 27024 plusmn 655 30668 plusmn 744 11355 plusmn 459 44784 plusmn 842PCB-15 ND 105 plusmn 51 0164 plusmn 002 0217 plusmn 003 0352 plusmn 011 0235 plusmn 012PCB-19 ND 49 plusmn 42 0013 plusmn 001 0025 plusmn 001 0083 plusmn 0037 0038 plusmn 004Mono-CBs 9547 plusmn 3535 6427 plusmn 636 3063 plusmn 616 3201 plusmn 655 2846 plusmn 459 510 plusmn 947Di-CBs 10461 plusmn 311 12186 plusmn 992 28523 plusmn 726 33893 plusmn 800 11464 plusmn 527 4931 plusmn 1128Tri-CBs 16057 plusmn 4667 4253 plusmn 127 4973 plusmn 109 2195 plusmn 109 1023 plusmn 512 8624 plusmn 143Tetra-CBs 17151 plusmn 707 5543 plusmn 141 5162 plusmn 253 6295 plusmn 279 2417 plusmn 147 7882 plusmn 362Penta-CBs 1875 plusmn 0007 1589 plusmn 735 6324 plusmn 16 1087 plusmn 334 1285 plusmn 099 6886 plusmn 368Hexa-CBs 1572 plusmn 0848 1974 plusmn 113 6242 plusmn 123 8965 plusmn 167 202 plusmn 0848 1231 plusmn 214Hepta-CBs 078 plusmn 0424 1214 plusmn 212 3485 plusmn 092 6758 plusmn 151 1359 plusmn 0424 1163 plusmn 165Octa-CBs 0587 plusmn 0283 1919 plusmn 99 2436 plusmn 061 4744 plusmn 123 1262 plusmn 028 511 plusmn 129Nona-CBs 0102 plusmn 001 461 plusmn 226 0378 plusmn 003 7057 plusmn 189 0226 plusmn 014 877 plusmn 173Deca-CBs 0213 plusmn 0007 165 plusmn 113 0984 plusmn 055 3109 plusmn 079 0082 plusmn 031 5485 plusmn 094sum209 PCBs 13244 plusmn 3069 14541 plusmn 1397 37274 plusmn 927 4033 plusmn 1014 18753 plusmn 641 6432 plusmn 1123SS (mgL) 450 1 lowast 104 100 2 lowast 103 1 lowast 103 2 lowast 104

SPM suspended particulate matter RW mixing influent (raw wastewater) PSS primary sedimentation sludge AHE anaerobic hydrolysis effluent ASactivated sludge HCS high-density clarifier sludge FS final sludge ND not detected sum Ind sum indicator PCBs and sum DL sun DL-PCBs

the PCB isomers with only 300 and 392 in the solidphase although the adsorbed fractions of other PCB isomerswere all above 65 in this stage Generally better removalcan be obtained for higher MW congeners by sorption ontoparticles or microbes owing to their high hydrophobicity [11]But what was reason about this unusual result As seen fromTables 2 and 3 the mean concentrations of dissolved Nano-CBs and Deca-CBs were 318 and 82 pgL in HCE and the

average levels of adsorbed Nano-CBs and Deca-CBs were0226 and 0082 ngg respectively On the one hand maybedue to the very low concentrations of them in dissolved(possible) oxidation by ferrate or flocculationadsorption byFe(OH)

3cannot occur accompanied with the competitive

effect among various pollutants On the other hand thefraction remaining in the treated wastewater unexpectedlyhigh for hydrophobic compounds could be explained by


Deca-CBsNona-CBsOcta-CBsHepta-CBsHexa-CBs

Penta-CBsTetra-CBsTri-CBsDi-CBsMono-CBs

RW PSE AHE SSE HCE PSS AS HCS FS0

20

40

60

80

100

Con

cent

ratio

n (

)

Wastewater and sludge samples

Figure 2 PCB isomer profiles in wastewater and sludge samples ofthe WWTP

0

20

40

60

80

100

Sorb

ed P

CBs (

)

RW PSE AHE SSE HCE

Mono-CBsDi-CBsTri-CBsTetra-CBsPenta-CBsHexa-CBs

Hepta-CBsOcta-CBsNona-CBsDeca-CBsΣPCBs

Figure 3 Distribution of PCBs in the adsorbed phase of the influentand effluent of each treatment stage

possible adsorption of PCBs onto nonsettleable solids whichremain in the wastewater stream due to the lack of chemicalcoagulation [28]

35 Removal of PCBs throughout the Treatment Processes inthe WWTP Based on the mean concentrations of dissolvedPCB isomers in each treatment stage the mean removals canbe calculated using the general equation

119877 () =(119862in minus 119862out)

119862intimes 100 (1)

where 119862in and 119862out are the daily amounts of PCBs enteringand exiting each treatment stage respectively The results areshown in Figure 4 Poor removal efficiencies were obtained inprimary sedimentation and anaerobic hydrolysis stage whichmay be due to the competitive adsorption between pollutantsand the selective adsorption of PACflocculants and anaerobic

0

20

40

60

80

100

Prim

ary

sedi

men

tatio

n

Ana

erob

ichy

drol

ysis

Aero

bic b

io-

proc

ess

Hig

h-de

nsity

clarifi

er

Who

le tr

eatm

ent

proc

ess

Rem

oval

()


Hepta-CBsOcta-CBsNona-CBsDeca-CBs

minus20

ΣPCBs

minus528

minus150

minus118

minus587

minus182

minus322

Figure 4 Mean removal percentages of dissolved PCB isomersduring each treatment stage

sludge In the following treatment stages removal efficienciesfor most PCB isomers were around or above 40 exceptfor Di- Nona- and Deca-CBs in aerobic bioprocess and Di-and Tetra-CBs in high-density clarifier stage Furthermoreinterestingly removal efficiencies of several PCB isomers(Octa-CBs andNona-CBs in primary sedimentation Tri-CBsand Tetra-CBs in anaerobic hydrolysis etc) were negative(below zero) as shown which resulted from the surge of thePCBs in the effluents

Throughout the whole treatment process the totalremoval efficiency of sum209 PCBs was 232 In detail theremoval efficiencies of Di-CBs and Nona-CBs were thelowest among all the isomers (88 for Di-CBs and 207for Nona-CBs) The removals of other PCB isomers werehigher than those Especially for Mono-CBs and Hexa-CBsthe removal efficiencies were higher than 90 and highefficiencies of over 80 were achieved for Penta-CBs andHepta-CBs In comparison the removals of PCBs were 20ndash91 in 26 WPCPs in New York and average removal were773 described by Durell and Lizotte [23] Higher removalwas found in the WWTPs in Norway with more than 90removal [24] This was because PCB concentrations werevery low with pgL grade in the WWTP tested and theconcentrations in other WWTPs were with ngL grade Thelower the concentration of PCBs is the more difficult theirremoval becomes

Based on the results above and other published papersthe removals of hydrophobic chemicals in wastewater treat-ment system are strongly dependent on their sorptive behav-iors [8 12] The adsorption of the hydrophobic organicpollutants is generally affected by their octanol-water par-tition coefficients (119870ow) In order to verify whether thesefindings are applicable to the WWTPs in China the removal


50 55 60 65 70 750

20

40

60

80

100

120


Anaerobic hydrolysisAerobic bioprocessHigh-density clarifierWhole treatment process

Rem

oval

()

logKow

R2

Primary = 034

R2

Aerobic = 027

R2

whole = 056

R2

Anaerobic = 031

R2

High-density = 019

Figure 5 Percent removal of individual PCBs versus log119870ow in eachtreatment stage

efficiency of each PCB congener is plotted against the log119870ow[29 30] which is shown in Figure 5 There was a weaklinear correlation (1198772 = 056) between the removal of PCBcongeners and their log119870ow values in the whole treatmentprocess However a relatively poor linear relationship (1198772019ndash034) was observed in primary sedimentation anaerobichydrolysis aerobic bioprocess and high-density clarifierstage which indicated that except for adsorption on sludgeparticles or microorganisms other mechanisms such asadvection volatilization biotransformation or (possible)oxidation and coagulation by ferrate might also be importantfor the less hydrophobic compounds of this class (log119870ow52ndash72) [12 31]

4 Conclusions

Dissolved and adsorbed concentrations of twenty PCB con-geners and total PCBs (from Mono-CBs to Deca-CBs) weredetected in each treatment stage in a centralized WWTPlocated in a chemical industry zone in Zhejiang China It wasinvestigated that the industrial activities especially the dyeingchemical processes were the main sources of PCBs enteringthe WWTP The contribution of sum209 PCBs discharged bythe largest dyeing chemical group to the WWTP was about136

PCBs entering the WWTP could be dissolved in thewastewater or adsorbed onto the particulates The mostabundant PCB was PCB-11 in the liquid and solid phaseof each treatment stage accounting for more than 60of the total 209 PCBs Meanwhile the PCB levels in theWWTP sludge were much higher than the limit set byChinese regulated laws Thus the sludge was not suitable foragricultural purposes Partitioning behavior of PCBs betweenthe dissolved and adsorbed phases suggested that Di-CBswere the most dominant isomers in the WWTP accountingfor over 70 of sum209 PCBs 898ndash974 of Di-CBs were

mainly adsorbed on the particles and sludge in the influentand effluent of each treatment stage The total removalefficiency of sumPCBs (209) was only 232 throughout thewhole treatment process although more than 80 of Mono-CBs Penta-CBsHexa-CBs andHepta-CBswere removed Ineach treatment stage poor removal efficiencies were foundin primary sedimentation and anaerobic hydrolysis whichwas due to the difficult settlement and biodegradation ofPCB-11 Furthermore a weak linear correlation between theremoval of PCB congeners and their log119870ow valueswas foundthroughout the whole treatment process which indicatedthat except for adsorption on sludge particles or microor-ganisms othermechanisms such as advection volatilizationbiotransformation or oxidation and coagulation by ferratemight also be important for the less hydrophobic compoundsof this class

Conflict of Interests

The authors declare that there is no conflict of interestsregarding this paper

Acknowledgments

The authors would appreciate the financial support tothis study provided by MOST Project of China (no2008BAC32B06) and NSFC of China (nos 2107618820836008 20976158 20990221 and 21076189) and the KeyInnovation Team for Science and Technology of ZhejiangProvince of China (2009R50047) They are sincerely gratefulto Professor Jiang Guibin and Zhang Qinghua in ResearchCenter for Eco-Environmental Sciences ChineseAcademy ofSciences Beijing for providing us with sample pretreatmentand analytical method

References

[1] K C Jones and P de Voogt ldquoPersistent organic pollutants(POPs) state of the sciencerdquo Environmental Pollution vol 100no 1ndash3 pp 209ndash221 1999

[2] K Breivik A Sweetman J M Pacyna and K C JonesldquoTowards a global historical emission inventory for selectedPCB congenersmdashamass balance approach 1 Global productionand consumptionrdquo Science of the Total Environment vol 290no 1ndash3 pp 181ndash198 2002

[3] L A Rodenburg J Guo S Du and G J Cavallo ldquoEvidencefor unique and ubiquitous environmental sources of 331015840-dichlorobiphenyl (PCB 11)rdquo Environmental Science and Technol-ogy vol 44 no 8 pp 2816ndash2821 2010

[4] B Fraser ldquoResearchers find little-known PCB lsquopretty mucheverywherersquordquo Environmental Science and Technology vol 44 no8 pp 2753ndash2754 2010

[5] M Pandelova R Piccinelli S Kasham B Henkelmann CLeclercq and K W Schramm ldquoAssessment of dietary exposureto PCDDF and dioxin-like PCB in infant formulae available onthe EUmarketrdquo Chemosphere vol 81 no 8 pp 1018ndash1021 2010

[6] F Samara CW Tsai andD S Aga ldquoDetermination of potentialsources of PCBs and PBDEs in sediments of the Niagara RiverrdquoEnvironmental Pollution vol 139 no 3 pp 489ndash497 2006


[7] AMartinez KWang and K C Hornbuckle ldquoFate of PCB con-geners in an industrial harbor of lakeMichiganrdquo EnvironmentalScience amp Technology vol 44 no 8 pp 2803ndash2808 2010

[8] T Pham and S Proulx ldquoPCBs and PAHs in the Montreal urbancommunity (Quebec Canada) wastewater treatment plant andin the effluent plume in the St Lawrence riverrdquoWater Researchvol 31 no 8 pp 1887ndash1896 1997

[9] Y W Wang X M Li A Li et al ldquoEffect of municipal sewagetreatment plant effluent on bioaccumulation of polychlorinatedbiphenyls and polybrominated diphenyl ethers in the recipientwaterrdquo Environmental Science amp Technology vol 41 no 17 pp6026ndash6032 2007

[10] P-A Bergqvist L Augulyte and V Jurjoniene ldquoPAH and PCBremoval efficiencies in Umea (Sweden) and Siauliai (Lithuania)municipal wastewater treatment plantsrdquo Water Air and SoilPollution vol 175 no 1ndash4 pp 291ndash303 2006

[11] G Byrns ldquoThe fate of xenobiotic organic compounds inwastewater treatment plantsrdquoWater Research vol 35 no 10 pp2523ndash2533 2001

[12] A Katsoyiannis and C Samara ldquoPersistent organic pollutants(POPs) in the sewage treatment plant ofThessaloniki NorthernGreece occurrence and removalrdquoWater Research vol 38 no 11pp 2685ndash2698 2004

[13] H Liu Q Zhang Z Cai A Li Y Wang and G Jiang ldquoSep-aration of polybrominated diphenyl ethers polychlorinatedbiphenyls polychlorinated dibenzo-p-dioxins and dibenzo-furans in environmental samples using silica gel and florisilfractionation chromatographyrdquo Analytica Chimica Acta vol557 no 1-2 pp 314ndash320 2006

[14] US EPA ldquoMethod 1668 Revision A Chlorinated biphenylcongeners inwater soil sediment and tissue byHRGCHRMSrdquoWashington DC USA EPA No EPA-821-R-00-002 1999

[15] R Yang Y Wang A Li et al ldquoOrganochlorine pesticidesand PCBs in fish from lakes of the Tibetan Plateau and theimplicationsrdquo Environmental Pollution vol 158 no 6 pp 2310ndash2316 2010

[16] L Guo B Zhang K Xiao Q H Zheng andMH Zheng ldquoLev-els and distributions of polychlorinated biphenyls in sewagesludge of urban wastewater treatment plantsrdquo Journal of Envi-ronmental Sciences vol 21 no 4 pp 468ndash473 2009

[17] S Litten B Fowler and D Luszniak ldquoIdentification of a novelPCB source through analysis of 209 PCB congeners by US EPAmodified method 1668rdquo Chemosphere vol 46 no 9-10 pp1457ndash1459 2002

[18] D Hu and K C Hornbuckle ldquoInadvertent polychlorinatedbiphenyls in commercial paint pigmentsrdquo Environmental Sci-ence and Technology vol 44 no 8 pp 2822ndash2827 2010

[19] F Rajaei A Esmaili-Sari N Bahramifar M Ghasempouri andM Savabieasfahani ldquoAvian liver organochlorine and PCB fromSouth coast of the Caspian Sea Iranrdquo Ecotoxicology vol 19 no2 pp 329ndash337 2010

[20] W Herbst and K Hunger Industrial Organic Pigments Wiley-VCH Weinheim Germany 3rd edition 2004

[21] H L He Fine Chemicals Daquan Dyes (Chinese Version)Zhejiang Science and Technology Press Hangzhou China2000

[22] M Blanchard M J Teil D Ollivon L Legenti and MChevreuil ldquoPolycyclic aromatic hydrocarbons and polychloro-biphenyls inwastewaters and sewage sludges from the Paris area(France)rdquo Environmental Research vol 95 no 2 pp 184ndash1972004

[23] G SDurell andRD Lizotte Jr ldquoPCB levels at 26NewYorkCityand New Jersey WPCPs that discharge to the New YorkNewJersey Harbor Estuaryrdquo Environmental Science amp Technologyvol 32 no 8 pp 1022ndash1031 1998

[24] C Vogelsang M Grung T G Jantsch K E Tollefsen and HLiltved ldquoOccurrence and removal of selected organic microp-ollutants at mechanical chemical and advanced wastewatertreatment plants in NorwayrdquoWater Research vol 40 no 19 pp3559ndash3570 2006

[25] S J de Luca M Cantelli and M A de Luca ldquoFerrate vstraditional coagulants in the treatment of combined industrialwastesrdquo Water Science and Technology vol 26 no 9ndash11 pp2077ndash2080 1992

[26] Ministry of Environmental Protection of the Peoplersquos Republicof China ldquoDischarge standard of pollutants for municipalwastewater treatment plant (GB 18918-2002)rdquo

[27] S Morris and J N Lester ldquoBehaviour and fate of polychlori-nated biphenyls in a pilot wastewater treatment plantrdquo WaterResearch vol 28 no 7 pp 1553ndash1561 1994

[28] A Katsoyiannis and C Samara ldquoPersistent organic pollutants(POPs) in the conventional activated sludge treatment processfate and mass balancerdquo Environmental Research vol 97 no 3pp 245ndash257 2005

[29] D W Hawker and D W Connell ldquoOctanol-water partitioncoefficients of polychlorinated biphenyl congenersrdquo Environ-mental Science and Technology vol 22 no 4 pp 382ndash387 1988

[30] M F Yeh and C S Hong ldquoOctanol-water partition coefficientsof non-ortho- and mono-ortho-substituted polychlorinatedbiphenylsrdquo Journal of Chemical amp Engineering Data vol 47 no2 pp 209ndash215 2002

[31] T D Waite and K A Gray ldquoOxidation and coagulationof wastewater effluent utilizing ferrate (VI) ionrdquo Studies inEnvironmental Science vol 23 pp 407ndash420 1984

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy


Carbohydrate Chemistry

International Journal of


Journal of

Chemistry


Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of


Chromatography Research International


Applied ChemistryJournal of



Theoretical ChemistryJournal of


Journal of

Spectroscopy

Analytical ChemistryInternational Journal of


Journal of


Quantum Chemistry


Organic Chemistry International

ElectrochemistryInternational Journal of



CatalystsJournal of


Aerobic bioprocessAnaerobic hydrolysis

Waste activated sludge

Retu

rned

Activ

ated

slud

ge

SSE

Lift pump

PSS

ASHCS

HCE

Sludge thickener

Outgoing wastewater

Mixing regulation

Incoming sewer

High-density clarifier

RWPSE AHE

Belt filter

Disposal

FS


Secondary sedimentation

Figure 1 Flow chart of the centralized WWTP in Zhejiang China (f location of samplings) RW raw wastewater PSE primarysedimentation effluent AHE anaerobic hydrolysis effluent SSE secondary sedimentation effluent HCE high-density clarifier effluent PSSprimary sedimentation sludge AS activated sludge HCS high-density clarifier sludge and FS final sludge

(Lithuania) WWTP during the treatment process Based onthe above-mentioned two papers it is very likely that differentwastewater components and wastewater treatment processeshave significant effect on the PCBs fate In China owingto the rapid development in manufacturing industries thepollutants in wastewater are increasing dramatically whichincreased the variety and complexity of PCBs in wastewaterin WWTPs However few detail data are available for thefate and removal of PCBs in the WWTPs in China takingboth PCBs distribution inwater and absorption in sludge intoaccount

The aim of our study was to thoroughly investigatethe fate of PCBs in the conventional wastewater treatmentprocesses Here a WWTP treating dyeing chemicals anddomestic wastewater in Zhejiang province China was cho-sen in this project Firstly we investigated the PCBs in theWWTP contributed by the dyeing chemical industry Thenthe indicator PCBs dioxin-like PCB congeners and threelightly chlorinated biphenyls (PCB-11 15 19) and total PCBs(from Mono-CBs to Deca-CBs) were quantitatively analyzedboth in wastewater and sludge at each treatment stage in theWWTP The distribution of PCBs between the dissolved andadsorbed phases in the influent and effluent of each treatmentstage was investigated as well Furthermore PCBs removalefficiencies at each treatment stage and the key removalmechanismwere also studied Ourworkwill provide a deeperunderstanding of the PCBs fate in WWTP and a theoreticalbasis for the source control

2 Materials and Methods

21 Plant Description and Sampling

211 Plant Description The centralized wastewater treat-ment plant (WWTP) is located in a chemical industry zone

in Zhejiang province ChinaTheWWTP is located outdoorsand processes 90000ndash120000m3 of raw wastewater per dayAbout 70 of the total flow is contributed by industrialactivities especially by dyeing chemical industries in thezone as well as a small amount of domestic sewage Theinfluents of wastewater through pipelines first pass screeningand grit and grease chambers and then are fully mixed inthe mixing regulation tank to be the raw wastewater (iemixed influent) The wastewater treatment processes includeprimary sedimentation using chemical flocculants (polyalu-minumchloride PAC) anaerobicaerobic (AO) biochemicaltreatment (including anaerobic hydrolysis process by anaer-obic biofilter and aerobic bioprocess by activated sludge)secondary sedimentation for the settlement of activatedsludge and high-density clarifier by ferrate oxidation Theflow chart of the plant is shown in Figure 1

212 Sampling Sites The wastewater suspended particulatematter (SPM) and sludge samples were taken from theoutlet of each processing stage during late October and earlyNovember 2010 (October 26 and November 6) Duplicatesamples of wastewater were collected along the treatmentsystem to study the sampling reproducibility namely themixed influent of raw wastewater in the mixing regulationtank (RW) the effluents of primary sedimentation anaerobichydrolysis aerobic bioprocess secondary sedimentation andhigh-density clarifier tanks (PSE AHE SSE and HCEresp) Grab samples of sludge were collected from theprimary sedimentation tank (PS) the recirculation stream(activated sludge AS) high-density clarifier tank (HCS) andsludge thickener tank (final sludge FS) concurrently withthe wastewater samples All sampling containers were insequence washed with water acetone dichloromethane andthe wastewater samples before use












































PCBs(ngg dw)














20

40

60

80

100

Con

cent

ratio

n (

)



0

20

40

60

80

100

Sorb

ed P

CBs (

)

RW PSE AHE SSE HCE






119877 () =(119862in minus 119862out)

119862intimes 100 (1)


0

20

40

60

80

100

Prim

ary

sedi

men

tatio

n

Ana

erob

ichy

drol

ysis

Aero

bic b

io-

proc

ess

Hig

h-de

nsity

clarifi

er

Who

le tr

eatm

ent

proc

ess

Rem

oval

()



minus20

ΣPCBs

minus528

minus150

minus118

minus587

minus182

minus322






50 55 60 65 70 750

20

40

60

80

100

120



Rem

oval

()

logKow

R2

Primary = 034

R2

Aerobic = 027

R2

whole = 056

R2

Anaerobic = 031

R2

High-density = 019



4 Conclusions






Acknowledgments


References










































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of












































PCBs(ngg dw)














20

40

60

80

100

Con

cent

ratio

n (

)



0

20

40

60

80

100

Sorb

ed P

CBs (

)

RW PSE AHE SSE HCE






119877 () =(119862in minus 119862out)

119862intimes 100 (1)


0

20

40

60

80

100

Prim

ary

sedi

men

tatio

n

Ana

erob

ichy

drol

ysis

Aero

bic b

io-

proc

ess

Hig

h-de

nsity

clarifi

er

Who

le tr

eatm

ent

proc

ess

Rem

oval

()



minus20

ΣPCBs

minus528

minus150

minus118

minus587

minus182

minus322






50 55 60 65 70 750

20

40

60

80

100

120



Rem

oval

()

logKow

R2

Primary = 034

R2

Aerobic = 027

R2

whole = 056

R2

Anaerobic = 031

R2

High-density = 019



4 Conclusions






Acknowledgments


References










































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of





20

40

60

80

100

Con

cent

ratio

n (

)



0

20

40

60

80

100

Sorb

ed P

CBs (

)

RW PSE AHE SSE HCE






119877 () =(119862in minus 119862out)

119862intimes 100 (1)


0

20

40

60

80

100

Prim

ary

sedi

men

tatio

n

Ana

erob

ichy

drol

ysis

Aero

bic b

io-

proc

ess

Hig

h-de

nsity

clarifi

er

Who

le tr

eatm

ent

proc

ess

Rem

oval

()



minus20

ΣPCBs

minus528

minus150

minus118

minus587

minus182

minus322






50 55 60 65 70 750

20

40

60

80

100

120



Rem

oval

()

logKow

R2

Primary = 034

R2

Aerobic = 027

R2

whole = 056

R2

Anaerobic = 031

R2

High-density = 019



4 Conclusions






Acknowledgments


References










































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


50 55 60 65 70 750

20

40

60

80

100

120



Rem

oval

()

logKow

R2

Primary = 034

R2

Aerobic = 027

R2

whole = 056

R2

Anaerobic = 031

R2

High-density = 019



4 Conclusions






Acknowledgments


References










































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of




































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of

Research Article Polychlorinated Biphenyls in the ...

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