Removal of cyclops in pre-oxidizing cooperation water treatment process

1826Liu et al. 1J Zhejiang Univ SciA 2007 811):1826-1830Journal of Zhejang University SCIENCEAISSN 1673-565X (Print; ISSN 1882 1775 (Online)www.zju.edu. cn[izus; ww.sprngerlink.comE-mad; jzus@zju.edu.cnJzuSRemoval of cyclops in pre-oxidizing cooperationwater treatment processLIU Dong-mei*12, CUI Fu-yi12, WU Ya-qin', LIN Tao', ZHANG Min', YU Ming-xue'('School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin 150090. China)(State Key; Laborutory of Uirbam Water Resource and Environment, Harbin 150090, China)(College of Envirormental Science and Enginering, Hohai Universiy, Nanjing 210098. China)E-mail: mei18@hit.edu.cnReccived Jan. 22, 2007; revision acepted May 20, 2007Abstract: Zooplankton cyclops propagates profusely in waterbody, cannot be eftiveley inactivated by conventional disinfec-tion process, and becomes a troublesome drinking water treatment problem. In this work, the qualitative and quantitative ex-perimental studies were carried out on inactivation of zooplankton cyclops using oxidants, such as chlorine (Cl2). chlorine dioxide(ClO2) 0ozone (O3), hydrogen peroxide (H2O2), 0ozon/hydrogen peroxide (Oy/H2O2), chloramines (Cz2-NH3) and potssiumpermanganate (KMnO4). The influences of various factors include different oxidant dosages, organic substance contents and pHvalues. The results showed that currently available oxidants used all might inactivate cyclops in sone extent. According to theexperimental results, chlorine dioxide. ozone, ozone/hydrogen peroxide and chloramines can be selected as efective oxidants forinactivating cyclops because of their strong inactivation abilities. Then the synergic removal efects on cyclops with ozone,ozone/hydrogen peroxide pre-oxidation followed by conventional water treatment processes were investigated. The resultsshowed that ozone and ozone/hydrogen peroxide pre oxidation can inactivate cyclops effectively, which then can be renovedthoroughly by conventional water treatment processes. Cyclops cannot appear in water after filtration with 1.65 mg/L of ozone and6 mg/L of hydrogen peroxide, with the inactivation rate being 62% before conventional water treatment processes. Cyclops cannotappear in water after filtration with 1.8 mg/L of ozone, with the inactivation rate being 50% before conventional water treatmentprocesses. For diferent oxidants, when removal rate was the best, the inactivation rate was not the same. These results may pro-vide reference and model for actual waterworks.Key words: Cyclops of zooplankton, Water treatment, Inactivation, O3. OyH2Oz pre-oxidationdoi:10.163 1/jzus.2007.A1826Document code: ACLC number: TU991INTRODUCTIONfrom sand filter into the clear water tank in water-works, even municipal distribution network. It is aEutrophication caused by water pollution resultsnuisance to water consumers and may become diseasein excessive propagation of zooplankton cyclops in transmission medium as the host of pathogenic para-waterbodies, which are hard to be removed by thesite, like schistosome or eelworm, to threaten humanconventional disinfection processes like chlorination health (Cui et al, 2005; Lin et al, 2006; Liu et al,due to its strong resistance to oxidation. In adition,2004a; 2004b).the motility of cyclops enables it to easily penetrateThe occurrence of cyclops which penetrates thefilter tank in drinking water showed that it cannot bethoroughly removed from water by the conventional' Proje supported by the Hi-Tech Research and Development Pro-wat中国煤化工ation, sedimenta-gram (863) of China (No. 2006AA06Z311), the Postdoctoral SciencetionF4a; 2004b; 2005;Foundation of Heilongjiang Province (No. LRB05-164), and theExellent Young Teacher Encouragement Project Foundation of HIT2006;MHc N M H Gyelops wih con-(No. HIT2006), Chinaventional water treatment process, and then, the fea-Liu et al. 1J Zhejiang Univ SciA 2007 8(1):1826-18301827sibility to remove it by chemical pre-oxidation in tional process were further experimented on.cooperation with the conventional process are putforward in this paper. The following steps are con-sidered: thorough inactivation of cyclops utilizing RESULTS AND DISCUSSIONoxidants, ihibiting its activity by pre-oxidation andthen removing it thoroughly by subsequent clarifica- Comparison of inactivation effects of differenttion process (Kanio and Kimata, 2000; Reckhow et al，oxidants on cyclops1990; Fiessinger, 1991).The experiment was conducted in a given vol-To inactivate or weaken cyclops with oxidants ume of distilled water solution free of other extrane-was believed to be the key to removing cyclops ous oxidant-demand substances but cyclops. Thecompletely from water treatment system (Ruffell et inactivation of cyclops with seven oxidants was in-al, 2000; Gunter and Pinkermell, 2000; Driedger et al, vestigated under various working conditions of dif-2001). So its inactivation with currently available ferent oxidant dosage, organic substance content andoxidants such as chlorine, chlorine dioxide, ozone, pH value. In the experiment, the number of cyclopshydrogen peroxide, ozone/hydrogen peroxide, chlora- was controlled to 10 ind./L, and the oxidants dosemines and potassium permanganate was researched ranged from 0.5 mg/L to 2.0 mg/L (the dose of chlo-experimentally. By comparison, chlorine dioxide, rine for chloramines, and the dose of ozone forozone, ozone/hydrogen peroxide and chloramines ozone/hydrogen peroxide).pre-oxidation were practicable methods to inactivate1. Influence of dose of oxidants on the inactiva-cyclops in water. Then the synergic removal effects on tion of cyclopscyclops with ozone or oz0ne/hydrogen peroxideA series of experiments revealed that the cyclopspre-oxidation followed by conventional water treat- inactivation with seven oxidants was strengthenedment processes were investigated. The conclusions gradually as the dose was increased. At pH value ofgained could be used for reference for waterworks.7.0, after reaction at 20。C for 30 min, the inactivationrates with oxidant dose of 1.0 mg/L were observedand the results are shown in Table 1, showing thatEXPERIMENTAL MATERIALS AND METHODS100% of cyclops may be inactivated by lower dose ofoxidants in the case of chlorine, 0zone,The experinents were crried out in two phases: ozone/hydrogen peroxide and chorine dioxide. TheFirst, the cyclops inactivation with seven oxidants incivation capaciries ofhese seven methods maybewas studied in the laboratory; then, further study of itsranked as follows: O/H2O2=CIlO>>Oz>Cl>CI2-NH3removal by oxidants pre-oxidation in cooperation >KMnO,>H2O2.with clarification process was conducted.We first investigated distilled water solution,Table 1 Comparison analysis of inactivation efets ofCyclops was sampled from a reservoir in Harbin, andseven oxidants on cyclopscultured in laboratory. In the experiment, the numberOxidantsInactivation effectDose of oxidantsof cyclops was contolled to 10 ind./L, the pH valueon cyclops (9%)(mg/L)Cl702.0of water sample was regulated with diluted acetic acidsolution or sodium hydroxide solution with the or-CIO21001.ganic substance in water sample being composed ofhumic acid, which was added according to the ex-H2O20600 (reacting 6 h)perimental demand. All analytical methods were0/H2O20; 1.0, H024conducted according to the Manual of Standard Ex-Cl-NH3Cl2 available 3.0 (90% only)amination Methods.KMnO4102.0 (75% only)Chlorine dioxide, ozone, 0zo0ne/hydrogen per-with dose of 1 me/L: " with 100% of inactivation efectoxide and chloramines were selected as preferable中国煤化工oxidants for comparison. Then the inactivation effectsCHCNMH(_only lttle poten-on cyclops by conventional process alone and in co-tial to.as not studied inoperation with oxidants pre-oxidation and conven- the following experiment.1828Llu et al. 1J Zhejiang Univ SciA 2007 811):1826- 18302. Influence of pH value on the inactivation of ammonia was changed from 1:1 to 3:1, with 2.0~3.0cyclopsmg/L of chlorine available, the inactivation of cyclopsThe inactiation efet of potassium permanga-all could be more than 50%.nate on cyclops was affected by pH value to a certainAccording to the result above, the adaptability ofextent; the efficiency of it was the lowest comparedthese methods for organic content may be ranked aswith other oxidants. With continually increasing pH，fllows: ClO2>0/H2O>Cl-NHz>CIl>KMnO>03.its inactivation rate trended to drop. As for ozone/hy-drogen peroxide, there was no large change of the Full-scale study of removing cyclops by pre-oxi-inactivation effect at certain rang of pH value. The dationeffcts of chlorine dioxide and ozone on cyclops in-1. Results of removal of cyclops by conventionalactivation were affected by pH value to the samewater treatment processesextent; 100% of cyclops may be inactivated by themIn the experiment, three parallel samples whichafter reaction at 20。C for 30 min at different pHwere assembled in the lab were used for each group ofvalues. The effect of chloramines on cyclops inacti-test, with the water quality indexes being as follows:vation was affected by pH value sensitively, becauseaverage water temperature: 24 °C; turbidity: 16 NTU;HOCI plays the main role in inactivating cyclopsCODmn: 3.86 mg/L; pH: 7.1 and cyclops were addedusing chloramines, just as chlorine. At the pH valueaccording to the experiment demand. 35 mg/L ofranged from 4.5 to 9.0, the adaptability of theseAICl3 were added into each sample as coagulant.methods for pH value may be ranked as follows: CIO2After 30 min' s reacting in six couplet timing strer,≈O}/H2O2=O;>Cl>Cl2-NHz>KMnO4.the number of cyclops was investigated, and then the3. Influence of organic content on the inactiva-supernatant water after jar test was filtrated. The fil-tion of cyclopstration velocity was 9 m/h, the time was 8 h, and theThe inactivation efficiency of each oxidant de-results are shown in Table 2, showing that the filtra-clined with increasing organic content, because thetion process had much more visible removal effectreductive organic substances in water cause the extra than coagulation and sedimentation. Its removal ratedepletion of oxidants. Especially, the influence ofwas 50% which was quite close to 56.7% for com-organic content on the inactivation effects of ozone bination processes, so in conventional water treat-was the most visible, with the inactivation rate de-ment processes, filtration plays the main role in re-creasing from 100% to 40% in the range of organicmoving cyclops.content from 0 to 8.8 mg/L with the ozone dose of1.8mg/L and reacting for 30 min. The influence of or-Table 2 Removal resuts of cyclops by conventionalganic content on the inactivation efects ofozone/hydrogen peroxide is also visible. While theOriginaJ Rudimental RemovalAveragerateof removalWater treatment number of numberof rate ofmore ozone added, the less the influence of organicsprocessescyclops cyclops cyclopsrate ofon the inactivation is. With the dose of 3 mg/L of(ind/L) (ind/L)(%)ozone and 10 mg/L of hydrogen peroxide, the influ-CoaglGroup 120ence of organic content on the inactivation effects wastion and Group2013.3quite invisible. The inactivation of cyclops with po-sedimen-10tation Group3tassium permanganate was also greatly influenced bySthe changes of organic content. For each 2.5 mg/L ofFiltration Group255.650.0organic content added, inactivation of cyclops wouldGroup 344.4be decreased by 10%~20% for potassium perman-Group 1.6(ganate. But the inactivation efficiency of chlorineCombinationGroup2 1056.7dioxide was less influenced which still kept at aboutGroup35C80% under the organie content of 10 mg/L condition.For each 2.5 mg/L of organic content added, inacti-中国煤化工s by ozone andvation of cyclops would be decreased by 10%~20%ozonC N M H Gation coopcratingfor chloramines. When the proportion of chlorine and with conventonal processesLiu ot al. 1J Zhejiang Univ ScIA 2007 8(1):1828-18301829In the experiment of ozone/hydrogen peroxide cooperation. So the inactivation rate was not in directpre-oxidation cooperating with conventional proc- ratio to removal rate. For different oxidants, whenesses, the samples were also assembled in the lab and removal rate was the best, the inactivation rate wasthe water quality was the same as before. Two oxi- not the same. These results could be used for refer-lants (ozone and hydrogen peroxide) were added ence, and different waterworks could choose the fea-sequentially, ozone first. In the experiment, the dose sible water treatment processes according to the ac-of hydrogen peroxide was 10 mgL, while ozone dose tual condition and water quality demand. Consideringwas changed. Coagulation, sedimentation and filtra- the practical differences in application, ozone pretion experiments were conducted after 30 min's oxidation and ozone/hydrogen peroxide pre-oxidationpre-oxidation. The experimental method was the were both put forward as feasible methods for re-same as before with the results being shown in Fig.1a. moving cyclops, and can be selected in practice ac-As can be seen, the removal rate of cyclops is quite cording to the practicality.similar when the dose of ozone is more than 1.4 mg/L.The removal rate reaches 100% with 1.65 mg/L of。100pozone.邑80Then ozone dose was adjusted to 1.65 mg/L with7(the hydrogen peroxide dose ranging from 0 to 10mg/L during the full-scale study. The results are50shown in Fig.1b. As can be seen from Fig.1b, the03 (mg/L)influence of hydrogen peroxide dose on the removal(aof cyclops is evident in certain range. Consideringeconomical factor, it is better to choose the lowesti 90↑amount in the feasible dose range. So 6 mg[L of by-80-drogen peroxide is suggested, correspondingly, the70inactivation rate is 62%。Although the cyclops was言6(not inactivated absolutely under that condition, the45678910activity of some cyclops was greatly weakened byH2O2 (mg/L)inactivation of oxidants, and may deposit together(bwith the flocs formed in the flocculation process. SoR100Ithey are effectively removed supematant upper water; 9080by the clarification process.In experiment of ozone peroxide pre-oxidation， 60cooperating with conventional processes (Fig.1c), theremoval rate can be 100% with 1.8 mg/L of oz0ne,1.61.12.0O3 (mg/L)correspondingly, the inactivation rate was only 50%.(cThe two methods of ozone and ozone/hydrogenFig,1 Removal effects on cyclops of OyH2O2; peroxideperoxide pre- oxidation cooperating with conventionalpre-oxidation cooperating with coaventional watertreatment processes, both had perfect effect on re- treatment proeses (a) at various 03 doses and (b) atmoval of cyclops, and both could remove cyclops various H2O2; doses, and (c) on cyclops of ozone peroxidethoroughly with relatively low dose of oxidant. Thepre-oxidation cooperating with conventional processesinactivation capacities of ozone were lower than thatof ozone/hydrogen peroxide, but ozone could weakenthe activity of cyclops, so that they were efectively CONCLUSIONremoved from supermatant water by clarificationprocess. In the process of ozone/hydrogen peroxideCurrent available oxidants used might all inac-pre-oxidation, ozone played the more important role, tivate中国煤化工rding to inactiva-while hydrogen peroxide played the role of catalyst tion e:Y HCNMH G_fuence, chlorineduring the whole reaction including inactivation anddioxide,vcuine, UcUiC/ iyuiugui peroxide and1830Liu et al. 1J Zhejiang Univ SciA 2007 8(1):18268 1830chloramines all have relatively high inactivation ef-spp. oocysts with ozone and ulraviolet iradiation evalu-fect, and can be selected as effective oxidant for in-ated by in vitro excystation and animal infectivity. Wat.Sci. Technol, 41():119-125.activating cyclops.The combination of pre-oxidation and conven-Lin, T, Cui, F.Y, Liu, D.M, Ma, F, Zhang, LQ, 2006. ffectof food habis of some fishes on the biomanipulation intional water treatment processes had perfect removaldrinking water source management. Journal of Harbineffect and cyclops can be removed thoroughly atInstitute of Technology, 38(1):35-37.lower dose of oxidants.Lin, D.M., Cui, FY, Lin, T, Zhang, LQ.2004a. PreliminaryThe inactivation rate was not in direct ratio tostudy on biological control of cyclops of zooplankton indrinking water source. Journal of Harbin Institute ofremoval rate. For diferent oxidants, when removalTechmology (New Series), 11(2):184-190.rate was the best, the inactivation rate was not theLiu, D.M., Cui, F.Y, Lin, T, An, D., Zhao, Y.C, Zhang, F,same. .Zheng, X.S.. 2004b. Studies on the conditions of the re-moval method of zooplankton from waler treatmentReferencesprocess. Journal of Harbin Institute of Technology,Cui, F.Y, Lin, T, Liu, D.M, Zhang, L.Q., 2005. Excess36(4):546-549.propagation and biological control of zooplanktonic cy-Liu, D.M, Cui, F.Y, He, W.J. Han, H.D., Zhang, M., Wu, YQ.,clops in drinking water sources. Hat. Sci. Technol,Lin, T, 2005. Experimental studies of inactivation effect52(8);151-159.on cyclops of zooplankton in water with ozone. Journal ofDriedger, A.M., Renecker, JL, Marinas, B.J, 2001. Inacti-Harbin Instiute of Technology, 37(sup,):269-272.iu, D.M, Cui, F.Y, Lin, T, An, D., Zhang, M., 2006. Ex-and monochloramine at low temperature. War. Res.,perimental studies on oxidizing removal of cyclops of35(1):41-48. [doi: 10.1016/S0043-135400)00260-8]zooplankton. High Technology Letters, 12(1 ):86-90.Fiessinger, F， 1991. Advantages and disadvantages ofReckhow, D.A., Singer, P.C, Malcolm, R.L,, 1990. Chlorina-chemical oxidation and disinfection of ozone and chlorineion of humic materials: byproduct formation anddioxide. Science of the Total Environment, 18:245-246.chemical interpretations, Environment Science andGunter, U.V, Pinkernell, U，2000. Ozonation of bro-Technology, 24(11):1655-1664. (ol:0.102100081808005]mide-containing drinking waters: A delicate balance be-tween disinfection and bromate formation, Wat. SciRuffell, KM, Rennecker, JL, Marifas, BJ, 2000. Inactiva-Technol, 41(7):53-59.tion on of Cryptosporidium panum oocysts with chlorineKanio, Y., Kimata, L, 2000. Inactivation of cryptosporidiumdioxide. Wat. Res, 34(3):868-876. [doi: 10.1016/S0043-1354(99)00187-6]JZUS-A has been covered by SCI-E since 2007Welcome visiting our joumnal website: http://www.zju.edu.cn/jzusWelcome contributions & subscription from all over the worldThe editor would welcome your view or comments on any item in thejournal, or related mattersPlease write to: Helen Zhang, Managing Editor of JZUSE-mail: jzus@zju.edu.cn TelFax:中国煤化工:331YHCNMHG