Contaminations removal from static lake water by compound

J Shanghai Univ (Eng! Ed), 2010, 14(2): 94-99Digital Object ldentifier(DOI): 10.1007/511741-010-0204-1Contaminations removal from static lake water by compoundLIU Shu-yu (刘书字)-2,，WU Ming-hong (吴明红)，MA Fang(马放)2， 7Hang ie(张杰)2,GU Xiao-jing (顾晓婧)I1. School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444, P R. Ching2. School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin 150090,P. R. China(Communicated by JIA0 Zheng)@Shanghai University and Springer-Verlag Berlin Heidelberg 2010Abstract Urban wastewater treatment techniques could not be applied to improre the polluiant semoral lliency, due toits characteristics of closed and quiescent conditions of the static lake water. In this study, natural zeolite and coal cinder werechosen as fller compounds of the ecological filter. Static and dynamic experiments were carried out to study the remediationefficiency. Experime'ntal data show that removal eficiency of ammonia nitrogen (NH- -N) reaches 85% in both static anddynamic patterns and its removal eficiency reaches 97% when the recycling period is 1 h in dynamic condition. The maximumremoval eficiency of nitrite nitrogen (NO2 - -N) reached 98%, and the removal eficiency of total nitrogen (TN) is a maximumof 84%. The final efuent concentration of total phosphorus (TP) is 0.079 mg/L. Efuent recyeling could improve the nutrient(N, P) removal fficiently. Dissolved oxygen (DO) concentration could remain high with the water cycling. The filter worksefficiently on regulating pH to the standard level of healthy water.Keywords bio-remediation, compound substrate, static waterIntroductionintegrative ecological engineering. These natural sys-terms are often referred as examples of green technologyContamination of static lakes and shallow rivers isbecause of the use of plants. The coining of the termi-mainly caused by eutrophication. It is evident that thenology“ecological engineering”is traced back to Odumdrastic increase in the frequency and occurrence of al-in the 1960s3). It is an integration of two distinctive sys-gae blooms in lakes and rivers. It may lead to desirabletems: ecological synthesis and engineering analysis4changes in the water quality and limit the usage of theEcological engineering is“the design of sustainablewater body with respect to water supply, fishing, aes-systems, consistent with self-design and other ecologicalthetics and recreation4l. Characters of static water inprinciples, which integrates human society with the nat-landscaping function are different from other water bod-ural environment for the both beneft"5-6. It has beenies. They include natural lake water, constructed lake,practiced since the mid-1980s in China and the 1990s inrivers and so on. In urbanized environment, these kindsNorth America and Europel7-9l.of water bodies are almost static and easy to be pollutedEcological filter includes several main forms, such asin short period. At present, currently sewage treatmentbiological filtering ditch and constructed wetland. Thetechnique could not be applied directly to control thisadvantages of these systems are their low constructionkind of contamination. In domestic wastewater treat-and operating costs. They are appropriate for treatingment techniques, machines and complicated crafts pro-both small and large water bodieslgl10]. Ecological filtercess could not be applied in static waterl2].has also been designed to treat urban runfl11-121. ItThere are mainly three methods for lake water treat-can be used to remedy lake water and surface water.ment: chemical, physical and biological methods. InThe mainly fller is gravel. It works mainly throughchemical preparation, CuSO4 is used to control the al-filtering. Using this method, the normal removal effi-gae in lake water, but high concentration is toxic tociency of total nitrogen (TN) is about 70% at present,aquicolous biology. Mechanical cleaning as a physicaland the process is slow. There are some important fac-method costs too much. Ecological flter is a kind oftors. Physical configuration and chemical property ofReceived Nov.14, 2009; Revised Jan.4, 2010Project supported by the National Natural Science Foundation of China中国煤化工，the Shanghai LeadingAcademic Discipline Project (Grant No.S30109), and the Systems BioYHC N M H Ganghai UniversityCorresponding author LIU Shu-yu, Ph D, E-mail: lsyu79@yahoo.com.cJ Shanghai Univ (Engl Ed), 2010, 14(2): 94-9995substrate connect closely with the remediation eficiencyfilter until the filter was full of water. It was allowedand sustainability. The design of the process is also im-to stand in the filter for 12 h, and then fAowed outportant, such as mode and speed of water flowing.Irfrom the system. In dynamic experiments, all the waterthis paper, traditional substrate is replaced by zeolitewas pumped through the system at different recyclingand coal cinder to build a new kind of filter. Efluent isspeeds, and the recycling period was 6,3, 1.5, 1 h, rerecycled in diferent period to remedy static water. Pu-spectively.rification speed and contaminations removal efficiency isalso studied.Water infoWater pipe,ClapboardZeolite in general is characterized by high specificZcolic- superstratum"surface areas and high cation exchange capacity (CEC)..Out- flowing inIts rigid three-dimensional structures make it free of theCind:shrink and swell behavior associated with smectite clays.Fig.1”Structure of the ecological filterFor these reasons, zeolite can offer superior sorptionand hydraulic properties and is used a8 molecular sievesIn static experiments, the filter mainly has two func-and sorbents in wastewater treatmentt13-141. Zeolite hastions. One is the absorption of the substrate due to itsbeen particularly useful in removing cationic specieslarge specific surface, the other is the biological action ofsuch as ammonium, and some heavy metals from water.the abundant microbes in the filter. In dynamic work-In particular, clinoptilolites have been used to removeing pattern, oxygen with recycling water strengthens thecationic radioactive species (137Cs, 90Sr) from nuclearbiological function.plant wastewater and contaminated groundwaterl15-16).1.3 Water qualityThe division is based on the types of interactions beThe contaminated water used in this study was takentween the medium and the contaminants. Huang andfrom a static lake in Harbin, located in northeasternPetrovic have mixed zeolite with sand under the meadowChina. Eutrophication was heavy in this lake duringto reduce leakage of nitrogen and improve fertilizationJuly every year, and nutrient was released from the bot-eficientlyl17].tom sediment. The quality of infow water is shown inResearch has shown that coal ash has some absorp-Table 1. The pollutants include NH- -N, TN, totaltion capacity, which may allow it to be used for envi-phosphorus (TP) and the pH value of the water sam-ronmental benefit rather than being disposed as a waste.ple were measured to study the water quality. We con-The experimental and field data demonstrated that coaltraste this quality with the standard of landscaping wa-cinder in packed beds removed biological oxygen deter (China).mand (BOD), ammonia nitrogen NHI - -N), total Kjel-1.4 Analytical instrumentdahl nitrogen (TKN).That may allow it to be used forNH-N and NO2-N were analyzed by a 722-environmental beneft rather than being disposed of asspectrophotometer, TN was analyzed by a nitrogen mea-a wastell8. Hence natural zeolite and coal cinder weresuring unit, and TP was analyzed by inductively coupledchosen as two kinds of main compound substrate in theplasma optical emission spectrometer (ICP-OES), andecological filter instead of traditional flling.total organit carbon (TOC) by organic carbon analyzer1 Materials and method(VCPN).Table 1 Quality of infuent water1.1 Construction of the ecological filterCoal cinder and zeolite were the main fllers of theNHt-N/ TN/ParameterspHecological filter. Coal cinder were collected from coal-(mg:L-1) (mg:L-1) (mg:L- 1)burning stokehold stations, and all the materials were3.608-4.964- 0.082-8.500-sieved to remove particles with size being greater thanRange4.4287.101 0.2199.0808 mm.3.9395.9080.1698.870The ecology filter was 150 cm long, 30 cm wide and30 cm tall. The filter consisted of 5 cm thick coal cinderstandard of lands-0.5000.020 6.500- 8.500scaping water[19]at the bottom, 15 cm thick zeolite in the middle, and10 cm thick sand on the top of the filter. Clapboard2 Results and disscussionwas set vertically in the middle of the filter as shownin Fig.1. The filter was divided into two parts by the2.1中国煤化工aminationclapboard.ed water entered from1.2 Field experimentsone sYHC N M H Gther side of the filter.Static and dynamic experiments were conducted. InAfter that, contaminat concentration changed, and thestatic experiments, water entered from one side of theremoval eficiency of each items are shown in Fig.2.96J Shanghai Univ (Engl Ed), 2010, 14(2): 94-99■Influentficiency is 86% in static pattern. In dynamic pat-口EMluenttern, effluent recycles through the filter in the peri-ods of 6, 3, 1.5, 1 h, respectively. Hence NHt-N removal efficiencies are diferent. It ranges from85% to 97% when the recycling period changes from6h to 1 h. It could be reasoned that fast recycling isNH:-N NO2- -N TNTOC NOF-N TPbenefit for NHt-N removal. In this proces 8, adsorp-tion by zeolite keeps steady. Oxygen entering with re-Fig.2 Contaminats removalcycling water favors the aerobice oxidation of NHt- N,Here the concentrations of NH-N, NO2 - -N, andand improves NHI一N removal, The similar conclusionvas found n study of wetland21. The most removalTN decrease to diferent degrees. The removal efficiencyfficiency of TN is 84% when the recyeling period isfor NH-N is 81%, for NO2-N is 66%, and for TN is1 h, it is 18% higher than that of static pastern. For80%. During the water staying in the filter, substrates,water used in this study, nitrogen is mainly inorganic,plants, and microbes together purified the water. Whenoxygen blended with recycling water enhanced transi-the contaminated water flows through the fllers, threetion of inorganic nitrogen to organic nitrogen and thismain pathes lead to the decrease of NH - -N concen-transition increases with the recycling process. The re-tration. The first one is adsorption by zeolite. Zeolitemoval eficiency of TN also rises.could adsorb much NHt-N in water through ion ex-change. The second one is holdness and absorption byTable 2 Removal eficiencydayflowers roots, which absorb some nitrate for growth.The third one is mass of microbial community in theRecycling period/hRemnoval eficiency/%filter. Many microbes grow when the contaminated warNHt- -NTNter passes through the fillers, they can carry on someStatic.071biological action, and therein nitrification is most im-Dynamic6.0850portant. Thus biological nitrifcation and ion exchangeDynamic 3.09017are the main paths of NHt- -N removal. Mass of ni-1.593228trate microbes live in the holes of zeolite, which trans-9714form NHt- -N to NO2- -N and then to NO3- -N, andthis process removes some nitrouse contaminats. InFig.3, concentration of NO2 - N decreases and NO5-NRemoval efciency of TP in static pattern is only 2%.concentration increases at the same time. This changeIn this pattern, water fAows out from the sand layer, andshows that nitrification existing in the filter is an impor-phosphorus adsorption capability of sand is small, so TPtant nitrous contaminats removal process. TP concen-removal eficiency is small. It reaches 47% when the retration increases slightly in this process. In this processcycling period is 3 h, which is the highest in all thethe resting time is short, but adsorption of phosphoruspatterns. Water recycling makes the contaminats passby the substrate is a slow process and an adsorptionthrough different layers of the filter and contact withequilibrium exists in this process. The above processdifferent kinds of fllers. Phosphorus could be adsorbedshows that slightly contaminated lake water could beby many substrates that improve its removal efficiency.remedied in short time by the ecological filter. NitrousHowever this adsorption process could not be finishedcontamination could be removed mostly, which couldin short time, if the recycle is too quick, contact timenot be done by traditional filter. For example, in mostof contaminats with fllers is short, and the adsorptiontraditional filter, wetland could removal nitrogen morecould not be completed well, hence removal eficiencythan 70%, but is not enoughl20).of contaminats declines. Enough contact time between2.2 Contaminats removal in 72 hcontaminats and fllers could lead to high removal efi-To study the contaminats removal efficiency in theciency of phosphorus.diferent patterns, contaminats removal efficiencies in2.3 Process of contaminas removal in dif-72 h were calculated and the results are shown inferent recycling periodsTable 2.The processes of NHf- -N, NO2 - -N, TN and TP reNH- -N removal efficiencies of each pattern almoval in different recycling periods are shown in Figs.3-reach 85%. In static pattern, water rests in the fl-B.中国煤化工), the concentrationter for 12 h and it gives suficient time for theofe_the lowest in all pat-fillers to absorb NHt- N. Zeolite has strong seterns:YHCNMHGofNHt-N,NO2-lective adsorption of NH-N and the adsorptionN, and TN are 97%, 98%, and 84%, respectively. Efu-could be finished in short time. NHt- -N removal ef-ent concentrations of NHJ- -N, NO2-N, TN are 0.1,J Shanghai Univ (Engl Ed), 2010, 14(2): 94-99970.03, 1.129 mg/L, respectively. NHt- -N concentrationof NO;- -N also increases with the recycling speed asis lower than that prescribed in the Chinese standard ofshown in Fig.4. When NHt--N is transformed towater in landscaping function. In this pattern, TN reNO2- N, NO2 - -N is transformed to NO3 - -N simulta-moval efficiency is higher than that of surface flow reedneously and part of NHT- -N transformed to NO3 -Nfilter22.directly. NO2-N is the middle product of nitrifica-tion, which does not accumulate here. Incr easing the- <-6h -0-3hrecycling speed of water provides more oxygen for thesystem, and nitrification works more quickly.- 0-1.5h - x-1hAerobic microbes become more activated because ofoxygen into the system, which helps to decc mpose ni-trous contamination. The main path of phosphorusremoval depends on the reactivity between PO2- andAl3+, Ca2Ig2+ of the fllers, although it is a slow0.52.0 2.5 3.0process. When the contacting time shrinks, the removalefficiency fall down. This process is affected by bothFig.3 Removal of NHt- N under diferent cycling periodsphysical and chemical properties of the fllers. Removalof low concentration phosphorus is still a dificult task0.20in static lake water study.2.4 Change of dissolved oxygen- A-1.5h ---1hDissolved oxygen (DO) concentration is an impor-; 0.10tant parameter for aquatic environment. It affects thegrowth and activation capability of aquatic microbes.会0.05DO concentration is usually very low in eutrophicatedake, in most cases it is lower than 4 mg/L or even.5.0 1.5ess, especially in warm days. It is mainly caused bytidexcessive algae and high concentration of NH- -N inFig.4 Removal of NO2 - -N under diferent cycling periodsthe water. Because algae and NHt- -N consume massof DO, and then DO concentration of water becomes1.4rvery low, then many aerobic creatures die for lacking凿oxygen. Many methods were tried to increase DO in.of- 0-1.5h -*-1h.the water, for instance, some artificial fountain were.8-built in lake water to increase DO concentration. In.6this study, DO concentration in different recycling pei 0.43riods was investigated every hour from 9:00 a.m. to16:00 p.m. Data are shown in Fig.7. The initial con-00.5 1.0 1.5 2.0 2.5 3.0centration of DO is around 7. We could see that DOconcentration did not change much with time when therecycling period are6 h and 3 h. That is to say, DOFig.5 Removal of NOz under diferent cycling periodsconcentration could be kept at a certain degree in thesetwo patterns. Wben the recycling period is changed to←6h -o-3h1 h and 1.5 h, DO concentration increases to around-心一1.5h -*-1h11 mg/L until 16:00 p.m. This DO concentration couldsaimprove the water environment. Here, DO concentra-tion in system is improved with efluent recycling speed.Thus we could improve DO in water by controling therecycling rate in practice.2.5 Regulation of water pH0.5 1.0 1As an important parameter of water environ-mento mnmminituvstructure and activ-Fig.6 Removal of TN under diferent cycling periodsityo中国煤化工ecosystem. Excessiveacidnake the aqueous en-In Fig.3，when the contacting time between convironDH. CNMH Gnicaed wate, pa oftaminated water and fllers is shortened, efuent con-ten exceeds 8. Figure 8 shows that during the processcentration of NHt- N increases. Removal efficiencyof contaminated water recycling through the ecological98J Shanghai Univ (Engl Ed), 2010, 14(2): 94-99filter, pH value falls to 7.26 from 9.08. It remains atAcknowledgments The authors extend their sincere7.1 after 2.5 d. The final pH value reaches standard ofthanks to the Key Laboratory of Water Resources Utiliza-healthy water. When aquatic environment is too acidtion and Environment Pollution Control, Chinese Ministryor alkaline, most of microbes, hygrophytes and aquaticof Construction, at Harbin Institute of Technology and to allcreatures will die. The filter could regulate pH due tothe colleagues in the lab for their help. Thanks are also dueto Chinese Academy of Sciences for its support.its physical and chemical functions.Referen ces[1] CHAU K W. A three dimensional eutrophic ation mod-18ling in Tolo Harbour国. Applied Mathem atical Mod-16口Period6h 口Period3helling 2004, 28(9)8 849-861.■Period1.5h■ Period 1 h14[2] ZHU Liang. Contaminated water formation reason and12maint enanee Tmeasure (0]. Advances in Wacer Science,; 102002, 13(3): 383- 388 (in Chinese).8[3] ODUM H T. Experiments with engineering of marineecosystems [P]. Publication of the Institute of Marine6Science of the University of Texas, Texas, 1963: 374-4403.2[4] GoLLEY F. Considering theoretical and practical needsof ecology [J]. 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