多层渗滤介质系统去除城市雨水径流有机污染物

以屋顶和机动车路面雨水径流污染物为研究对象,设计了用于去除雨水径流污染物的多层渗滤介质系统,进行污染雨水净化效果的试验研究.结果表明,系统对屋顶和机动车路面雨水径流有机污染物有明显的去除效果,CODMn平均去除率为80%左右,出水浓度小于4mg·L-1,达到了地表水Ⅱ类水质标准;BOD5的去除率达50%以上,出水值达到了地表水Ⅱ类水质标准;同时,系统的净化能力主要发生在垫层及地基土层0.3m以内,污染严重的机动车路面径流在土柱底部也能达到很好的去除效果;"砂砾科"垫层对CODMn和BOD5,的去除效果稍好于"无砂混凝土"垫层.     

复合填料生物渗滤系统处理城市雨水径流的研究

为有效控制无锡市道路雨水径流面源污染,根据当地径流污染的特点,设计了能去除多种道路径流污染物的复合填料生物渗滤系统,进行污染雨水净化效果的试验研究.结果表明,系统对道路雨水中的悬浮性颗粒物(SS)、耗氧有机污染物(COD)和氮磷污染物均具有明显的去除效果;所有类型的复合填料生物渗滤系统对于SS均具有较高的去除率,能够达到90%以上;以活性炭填料为主的渗滤系统(GAC)对于COD和磷类污染物的去除效果相对较优,以沸石填料为主的渗滤系统(ZFM)对氮类污染物的去除效果相对较优.木屑在系统中的添加能够有效提高系统对氮类污染物的去除率;在系统中混合分散放置木屑的装填方式相较于集中分层的装置方式能够减少木屑溶出物的释放,可使系统达到更高的COD和氮磷污染物的去除效率.     

沸石改良雨水生物滞留系统去除污染物研究

作为重要的低影响开发技术之一,雨水生物滞留系统在控制径流污染和削减径流总量及峰值方面具有良好的效果。传统生物滞留系统对于TSS、重金属和COD有较好的去除效果,但对硝氮去除效果差,砂土填料空隙率小,对水量的调蓄效果差,水力停留时间长,容易堵塞。本研究尝试采用沸石作为滞留系统的基质填料,并在系统底部设置淹没区创造缺氧环境提高系统对硝氮的去除效果。对比了在有无淹没区条件下对模拟雨水中各种污染物的去除效果。在无淹没区条件下,系统对进水TSS负荷的变化有很好的抗冲击能力,当进水TSS浓度在100~400 mg/L范围内变化时,出水TSS始终在20 mg/L以下。当进水COD浓度为150~250 mg/L,TP浓度为2.5~7.0 mg/L,NH_4~+-N浓度为3.0~4.0 mg/L,NO_3~--N浓度为6.0~10.0 mg/L时,系统对COD、TP、NH_4~+-N、NO_3~--N的平均去除率分别为67%、73%、88%、5%。在有淹没区且进水浓度基本相同的条件下,系统对TSS、COD、TP、NH_4~+-N等污染物的去除均没有大的变化,但对NO_3~--N的平均去除率则上升为74%。同时,系统对Pb、Zn、Cu、Cd等重金属也有良好的去除效果。     

雨水径流截流渗滤系统控制城市面源污染的中试研究

设计雨水径流截流渗滤中试系统,监测其对汇水路面上降雨径流的长期净化效果,分析2次典型降雨径流的污染特征及系统处理效果.结果表明,路面径流污染严重,SS、COD、TN、TP的平均浓度分别为361、135、7.88和0.62 mg/L;长时降雨形成的径流表现出明显初期效应,前25%水量中所含的SS、TP、DTP及PO34-...     

分流比对土壤渗滤系统脱氮效果的影响研究

针对污染物浓度较高的养猪废水,开展了不同分流比条件下土壤渗滤系统处理效果的对比研究,并分析了分流比对系统中脱氮微生物数量及氧化还原电位(ORP)变化的影响.试验结果表明,分流比对土壤渗滤系统的脱氮效果影响较大,而对COD、TSS和TP的去除效果无明显影响,当水力负荷(HLR)为0.01m3·m-2·d-1且分流比为1∶2时,系统对TN的去除效果最好,平均去除率达80.20%,而对其他污染物的平均去除率均可达90%以上;分流比可影响土壤渗滤系统中脱氮微生物的数量,分流比的增大可促进系统中反硝化细菌数量的增加,强化系统的脱氮效果;另外,分流比还可影响系统填料层中ORP的变化.因此,根据系统进水水质选择合适的分流比,是强化土壤渗滤系统脱氮效果的关键因素.     

生物滞留介质类型对径流雨水净化效果的影响

生物滞留措施能够有效去除径流雨水中的污染物,而介质类型对其净化效果具有重要影响。该研究以粗砂、细沙、黏土、建筑垃圾为介质,研究了生物滞留单元对径流雨水中污染物的净化效果。结果表明,各单元对COD、氮、磷污染物的平均去除率分别为63.9%、62.2%、83.3%;Cd为77.2%,Cu、Pb、Cr、Zn均在92.9%以上。介质类型、介质填装方式、粒径级配等因素对氮、磷等污染物的净化效果影响较大,对重金属的净化效果影响较小。各种介质去除污染物能力依次为黏土细沙粗砂建筑垃圾;建筑垃圾的粒径越小,对径流雨水中污染物净化效果越好。基于上述结果,对各单元出水水质进行回用风险评估,黏土复合介质滞留单元的出水回灌地表水的风险最小;各单元出水均可满足绿地灌溉(GB/T 25499-2010)水质标准。     

改造滤岸对城市降雨径流中氮磷去除的中试研究

选择煤渣、锯末、沸石、麦饭石、土壤和马尼拉草构建了城市河岸带改造滤岸中试模型,并对其去除城市降雨径流中氮磷污染物能力进行了研究.结果表明,改造滤岸对表面径流和下渗径流中NH4+-N和TP具有良好的净化效果和较强的去除能力;NH4+-N平均去除率分别为66.5％和83.7％,TP平均去除率分别为42.6％和96.2％,出水水质分别可达国家地表水Ⅳ类和Ⅲ类水标准,模型稳定后对表层径流和下渗径流中TN的去除率可达20％左右;模型对NH4+-N、TN和TP的处理负荷分别为634.1～1114.5 mg-m-2·h-1、102.2 ～594.2mg· m-2·h-1和20.6～ 209.0 mg·m-2· h-1,表面径流大于下渗径流.模型内碳源(锯末)以及其他介质的添加虽然能够提高氮的转化能力,但也会影响模型对TN的去除率;下凹断面和末端断面对氮磷的去除率和去除负荷间存在一定的差异,但随着模型的稳定其差异逐渐降低.模型对氮磷的处理负荷与入水氮磷浓度呈显著正相关,说明模型具有一定的抗冲击能力.     

沙渗滤去除三家店水库水中有机污染物的试验研究

采用CODMn和BOD作为指标对沙渗滤系统去除三家店水库水中有机污染物的效果进行了评价.试验构建一个长约10m、宽2m、高2m的砖混结构渗滤池,渗滤池分隔为8个小渗滤池,选择3种不同的沙分别构建1m3见方的渗滤床.渗滤系统持续运行125d,经历高温的夏季和低温的冬季,试验结果表明,渗滤系统对三家店水库水中有机污染物能有效去除,CODMn去除率一般在20%～40%,BOD的去除率一般在20%～80%,CODMn、BOD的出水值分别小于4mg·L-1、3mg·L-1;渗滤层厚度的增加不能显著增加有机污染物的去除率;温度对CODMn和BOD的去除有明显的影响;3种渗滤介质对CODMn和BOD均能有效去除,建筑沙对去除有机质的效果相对好一点.     

生态工程综合治理系统对农业小流域氮磷污染的治理效应

以典型农业小流域——开慧河流域源区为研究对象,基于研究区农业面源污染的主要排放特征,建立以生态湿地为主的小流域面源污染生态工程综合治理系统,重点探讨其对水体氮磷污染物的去除效果.结果表明,畜禽养殖业是开慧河流域源区水体氮磷污染物的主要来源,需要重点防控.组合生态湿地处理工程对农村分散式生活与养殖混合废水总氮(TN)、总磷(TP)的平均去除率为87. 1%和90. 9%;多级人工湿地拦截工程对农田排水与分散式养殖混合废水TN、TP的平均去除率为85. 7%和84. 9%;景观型生态湿地净化工程对末端汇水区水体中TN、TP的去除率在27. 1%～67. 4%和13. 3%～81. 5%之间.整个生态工程综合治理系统对流域TN和TP污染物的总拦截量分别为5 292 kg·a~(-1)和1 054 kg·a~(-1),占研究区农业面源TN、TP总污染负荷的35. 3%和43. 6%.因此,构建的生态工程综合治理系统对流域农业面源氮磷污染具有较好的治理效应,适合在我国南方小流域水环境治理中推广应用.     

周丛藻类水质处理系统中氮、磷污染物去除效果研究

为了评价周丛藻类系统对受污染景观河道水体氮、磷污染物处理效果,以及最佳污染物去除浓度,通过设置周丛藻类水质处理系统,并模拟藻类自然生长条件,于2006年夏秋之季,对该周丛藻类系统的水质处理效果进行了研究.结果表明,①相对于标准培养液条件下20%的平均去除率,周丛藻类水质处理系统中TN、NH4 -N去除率分别可达30%和50%以上,其中TP平均去除率则相对较低(＜10%);②系统最大氮污染物去除率(TN＞65%,NH4 -N＞80%)出现在进水TN浓度约11.0mg·L-1条件下,而TP去除率则随进水浓度增加呈下降趋势;③试验期间,系统中周丛藻类生物量增加54%,Chl-a浓度增加58.2%,同时藻类群落由试验初期的颗粒态硅藻、绿藻为主,演替为以丝状和颗粒状蓝、绿藻为主.     

Distribution and ecological effect of mercury in Laogang landfill, Shanghai, China

Laogang landfill near Shanghai is the largest landfill in China, and receives about 10000 t of daily garbage per day, Samples of topsoil and plants were analyzed to evaluate mercury pollution from the landfill. For topsoil samples, there were significant correlations among total mercury （HgT）, combinative mercury （Hgc） and gaseous mercury （HgG）, and content of total organic carbon （TOC）, but, no significantly relationship was found between Hg content and filling time. Hg content changes in vertical profiles with time showed that the average Hgv of profiles 1992, 1996, and 2000 was similar, but their average HgG was quite different. HgT was significantly correlated with Hgc in profile 1992 and 2000, and Hgv was significantly correlated with Hg6 in profile 1996. HgG/Hgv ratio in profile samples decreased in the order of （HgG,/HgT）1992〉（HgG/HgT）1996〉〉（HgG/HgT）2000. A simple outline of Hg release in landfill could be drawn： with increasing of filling time, degradation undergoes different biodegradation, accordingly, gaseous mercury goes through small, more, and small proportion to total mercury. Distribution of Hg in plants was inhomogeneous, following the order of leaf〉root〉stem. The highest value of leaf may be associated with higher atmospheric Hg from landfill. Ligneous plants （e.g. Phyllostachys glanca, Prunus salicina and Ligustrum lucidum） are capable of enriching more Hg than herbaceous plants.     

EDTA-enhanced phytoremediation of lead contaminated soil by Bidens maximowicziana

Phytoremediation is a potential cleanup technology for the removal of heavy metals from contaminated soils.Bidens maximowicziana is a new Pb hyperaccumulator,which not only has remarkable tolerance to Pb but also extraordinary accumulation capacity for Pb.The maximum Pb concentration was 1509.3 mg/kg in roots and 2164.7 mg/kg in overground tissues.The Pb distribution order in the B. maximowicziana was:leaf>stem>root.The effect of amendments on phytoremediation was also studied.The mobility of soil Pb and the Pb concentrations in plants were both increased by EDTA application.Compared with CK(control check),EDTA application promoted translocation of Pb to overground parts of the plant.The Pb concentrations in overground parts of plants was increased from 24.23-680.56 mg/kg to 29.07-1905.57 mg/kg.This research demonstrated that B.maximowicziana appeared to be suitable for phytoremediation of Pb contaminated soil,especially,combination with EDTA.     

Decomposition of alachlor by ozonation and its mechanism

Decomposition and corresponding mechanism of alachlor, an endocrine disruptor in water by ozonation were investigated. Results showed that alachlor could not be completely mineralized by ozone alone. Many intermediates and final products were formed during the process, including aromatic compounds, aliphatic carboxylic acids, and inorganic ions. In evoluting these products, some of them with weak polarity were qualitatively identified by GC-MS. The information of inorganic ions suggested that the dechlorination was the first and the fastest step in the ozonation of alachlor.     

Enzymatic oxidation of aqueous pentachlorophenol

The influence of the nonionic surfactant Tween 80 on pentachlorophenol （PCP） oxidation catalyzed by horseradish peroxidase was studied. The surfactant was tested at concentrations below and above its critical micelle concentration （CMC）. Enhancement of PCP removal was observed at sub-CMCs. The presence of Tween 80 in the reaction mixture reduced enzyme inactivation which occurred through a combination of free radical attack and sorption by precipitated products. A simple first-order model was able to simulate time profiles for enzyme inactivation in the presence or absence of Tween 80. At supra-CMCs, the surfactant caused noticeable reductions in PCP removal, presumably through micelle partitioning of PCP which precluded the hydrophobic PCP molecule from interacting with the enzyme.     

基于综合水质标识指数和对应分析法的校园河道水质评价

以三峡大学的校园河道求索溪为研究对象,利用综合水质标识指数法确定求索溪水质类别,分析其水质时空变化规律,并利用对应分析法得出求索溪中不同监测点的主要污染因子.研究结果表明:求索溪整体的综合水质标识指数为7.423,整体水质为劣V类(地表水环境质量标准GB 3838-2002)且黑臭.从时间变化来看,求索溪4月份的水质最差,5月份次之,4、5月份所有监测点的水质都劣于V类且黑臭;8月份水质最好,水质为Ⅳ类;从空间分布来看,8个监测点综合水质标识指数均超过6.0,水质为劣V类,其中6号监测点的水质相对最好,监测点3号的水质相对最差;对应分析法得出求索溪的整体水体污染程度受总氮因子的影响最大,其次为总磷.该研究拟为求索溪及类似校园河道的水环境治理研究提供基础依据和参考.     

Effects of chitosan on growth of an aquatic plant (Hydrilla verticillata) in polluted waters with different chemical oxygen demands

Effects of chitosan on a submersed plant, Hydrilla verticillata, were investigated. Results indicated that H. venicillata could prevent ultrastructure phytotoxicities and oxidativereaction from polluted water with high chemical oxygen demand (COD). Superoxide dismutase (SOD) activity and malondialdehyde (MDA) contents in H. verticillata treated with 0.1% chitosan in wastewater increased with high COD (980 mg/L) and decreased with low COD (63 mg/L), respectively. Ultrastructural analysis showed that the stroma and grana of chloroplast basically remained normal. However, plant cells from the control experiment (untreated with chitosan) were vacuolated and the cell interval increased. The relict of protoplast moved to the center, with cells tending to disjoint. Our findings indicate that wastewater with high COD concentration can cause a substantial damage to submersed plant, nevertheless, chitosan probably could alleviate the membrane lipid peroxidization and ultrastructure phytotoxicities, and protect plant cells from stress of high COD concentration polluted water.     

Removal of cadmium using MnO2 loaded D301 resin

MnO2 loaded weak basic anion exchange resin D301 （Anion exchange resin, macroreticular weak basic styrene） as adsorbent has been prepared and applied to the removal of cadmium. The adsorption characteristics have been investigated with respect to effect of pH, equilibrium isotherms, removal kinetic data, and interference of the coexisting ions. The results indicated that the Cd^2＋ could be efficiently removed using MnO2 loaded D301 resin in the pH range of 3-8 from aqueous solutions with the co-existence of high concentration of alkali and alkaline-earth metals ions. The saturate adsorption capacity of the Cd^2＋ was 77.88 mg/g. The adsorption process followed the pseudo first-order kinetics. The equilibrium data obtained in this study accorded excellently with the Langmuir adsorption isotherm.     

Effect of coagulation pretreatment on the fouling of ultrafiltration membrane

The purpose of this study is to understand the effect and mechanism of preventing membrane fouling, by coagulation pretreatment, in terms of fractional component and molecular weight of natural organic matter （NOM）. A relatively higher molecular weight （MW） of hydrophobic compounds was responsible for a rapid decline in the ultrafiltration flux. Coagulation could effectively remove the hydrophobic organics, resulting in the increase of flux. It was found that a lower MW of neutral hydrophilic compounds, which could remove inadequately by coagulation, was responsible for the slow declining flux. The fluxes in the filtration of coagulated water and supernatant water were compared and the results showed that a lower MW of neutral hydrophilic compounds remained in the supernatant water after coagulation could be rejected by a membrane, resulting in fouling. It was also found that the coagulated flocs could absorb neutral hydrophilic compounds effectively. Therefore, with the coagulated flocs formed on the membrane surface, the flux decline could be improved.     

Penetration analysis of elements and bioleaching treatment of spent refractory for recycling

Acidithiobacillus ferrooxidans ATCC23270 and Acidithiobacillus thiooxidans TM-32 were used for bioleaching of spent refractories of aluminium and copper melting furnaces for their recycling.Firstly,penetration of elements into aluminium melting furnace refractory was investigated and it was found that up to 7 cm from surface was contaminated.Comparison on leaching efficiency by the strains ATCC23270 and TM-32 found that the strain ATCC23270 could treat larger amount of the refractories than the strain TM-32 could do.In the experiment of bioleaching of spent refractory aluminium melting furnace by the strain ATCC23270,high leaching efficiency were obtained on Al,Si,and Ca,and extremely low leaching performance was,however,shown on the rest of elements i.e.,Na,Mn,and Zn.Under the strain TM-32 use,relatively high leaching performance was recognized on Al,Si,Ca,Na,Mn,and Zn.In the experiment of bioleaching for spent refractory copper melting furnace,almost the same leaching trends were shown on Cu,Zn,Al,and Si under the strains ACTT23270 and TM-32 uses.     

Simultaneous removal of ammonium and phosphate by zeolite synthesized from coal fly ash as influenced by acid treatment

Zeolite synthesized from fly ash （ZFA） without modification is not efficient for the purification of NH4＋ and phosphate at low concentrations that occur in real effluents, despite the high potential removal capacity. To develop an effective technique to enhance the removal efficiency of ammonium and phosphate at low concentrations, ZFA was modified with acid treatment and the simultaneous removal of ammonium and phosphate in a wide range of concentration was investigated. It was seen that when compared with untreated ZFA, only the treatment by 0.01 mol/L of H2SO4 significantly improved the removal efficiency of ammonium at low initial concentrations. The behavior was well explained by the pH effect. Treatment by more concentrated H2SO4 led to the deterioration of the ZFA structure and a decrease in the cation exchange capacity. Treatment by 0.01 mol/L H2SO4 improved the removal efficiency of phosphate by ZFA at all initial P concentrations, while the treatment by concentrated H2SO4 （≥0.9 mol/L） resulted in a limited maximum phosphate immobilization capacity （PIC）. It was concluded that through a previous mild acid treatment （e.g. 0.01 mol/L of H2SO4）, ZFA can be used in the simultaneous removal of NH4＋ and P at low concentrations simulating real effluent.