多层渗滤介质系统对城市雨水径流氮磷污染物的净化作用

根据北京市雨水地表径流污染的特点,设计了用于去除屋顶和机动车路面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中的氮磷污染物有明显的去除效果,NH+4-N、TN、TP的去除率分别达80%、90%、50%以上,出水浓度达到地表水Ⅱ类水质标准;"砂砾料"垫层对TP的去除效果稍好于"无砂混凝土"垫层;雨水径流中氮磷浓度愈高则对氮磷的去除率愈高.雨水径流氮磷浓度变化对氮磷去除效果的影响较小.多层渗滤介质系统通过微生物的硝化和反硝化作用实现生物脱氮是系统去除氮的主要途径;土壤的吸附与沉淀作用是多层渗滤介质系统去除磷的主要途径.系统对城市雨水径流氮磷污染物的净化能力主要发生在垫层及地基土层0.3m以内.     

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。     

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.     

镇江市城区降雨径流水质分析

雨水径流污染是城市面源污染的主要形式,通过对镇江市城区2011年10场降雨径流水质监测,分析了镇江市城区降雨径流水质。结果表明,镇江市城区降雨径流存在一定污染,直接排入城市地表水体会对其造成污染。其主要污染指标为COD、BOD5、NH3-N、TP和总悬浮颗粒物,重金属含量较低,基本不存在重金属污染。各种不同类型雨水径流水质污染程度差异较大,天然降雨、屋面径流,大市口路面径流水质相对较好,基本能达到Ⅲ或Ⅳ类水体的水质标准;泵站、排口径流、河道径流污染较重,大多属于超Ⅴ类水体;南门大街路面径流污染最为严重,部分水质指标接近工业废水。     

北京市城市降雨径流水质评价研究

选取北京市城市天然雨水与3个不同下垫面(屋面、单位内部道路和环路干道道路)的降雨径流为研究对象,在2010年7～10月期间,测定了8场降雨中的13个理化指标,并采用灰色关联分析和主成分分析方法进行水质综合评价和污染物来源分析.结果表明,环路干道径流的综合水质最差,其他依次为屋面径流、单位内部道路径流和天然雨水,其中环路干道径流综合水质超出国家地表水Ⅴ类水质标准,天然雨水、单位内部道路径流和屋面径流综合水质满足国家地表水Ⅱ类水质标准;天然雨水与各下垫面降雨径流的主要污染物为氮,其中TN和NH4+-N平均浓度为5.49～11.75 mg.L-1和2.90～5.67 mg.L-1;环路干道径流中第一类污染物为P、SS和有机污染物,其主要来源为车辆轮胎和路面材质的磨损;第二类污染物为N和溶解态重金属,其主要来源为车辆尾气和大气干湿沉降.本研究结果可以为城市雨水水质评价、城市面源污染控制和雨水回收利用提供科学依据.     

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.     

新型人工湿地对工业区降雨径流的净化研究

根据东莞市同沙水库集水区内工业区降雨径流的水质、水量特征,采用新型折流式人工湿地对其进行模拟及实地降雨径流净化研究.对人工湿地不同运行阶段模拟降雨径流的净化效果进行对比,分析COD、SS、TN、TP、NH4+-N以及重金属Pb、Zn、Cu在湿地系统中的沿程变化,探讨它们的主要去除机制.模拟净化研究中,除TN外,湿地系统出水各污染物均达到《地表水环境质量标准》(GB 3838-2002)Ⅲ类质量标准,TN达Ⅳ类标准;且大部分污染物在湿地前端被去除.实地降雨径流净化研究中,COD、SS、TN、TP及NH4+-N的平均去除率分别为90.9%、97.0%、83.4%、92.2%、90.0%;重金属Pb、Zn、Cu的平均去除率分别为98.4%、94.1%、93.6%,出水均能达地表Ⅲ类水标准.研究表明,折流式人工湿地系统对工业区降雨径流的净化效果显著,湿地系统具有较强抗冲击负荷能力.另外,小幅温度变化对湿地系统中污染物的去除影响不大.     

植草沟控制道路径流污染效果的现场实验研究

在合肥市滨湖新区建造了2条不同形式的植草沟,在实际降雨条件下监测2种植草沟的进、出水流量与水质,考察其对道路径流的水质净化和污染负荷控制效果.结果表明,植草输送沟(设施Ⅰ)与干植草沟(设施Ⅱ)均能有效去除径流中的TSS、COD、Pb、Cu、Cd、Zn等污染物,设施Ⅰ对TSS及COD的去除率中值分别为67.1%、46.7%,设施Ⅱ对TSS及COD的去除率中值分别为78.6%、58.6%,设施Ⅱ出水中Pb、Cu、Zn这3种重金属离子浓度均可达到地表水Ⅴ类水的要求;2种植草沟在部分降雨事件出水中均存在氮、磷物质的释放现象;2种植草沟对TP的去除受进水浓度的影响,去除效果随进水浓度的增加而逐渐提高,设施Ⅰ和设施Ⅱ对TP的平均去除率分别为14.7%和45.4%;设施Ⅱ对TSS、COD、TP、TN、NH+4-N、NO-3-N的负荷控制效果优于设施Ⅰ;在土壤渗透性能差、地面坡度小的地区,使用干植草沟可以取得较好的水质控制及污染负荷削减效果.     

广州市城区降雨径流水质特征分析

通过对广州市城区2008年-2009年大量的降雨径流水质监洲,研究了广州市城区降雨径流水质的特征。结果表明,广州城区地表径流水质的未达到污水排放的二级标准,若直接排入城市地表水体可能对其造成污染,因此,对待城市地表径流水应该如对待污水一样处理。对于CODcr、BOD5、TN、TP浓度,路面径流要高于屋顶径漉;而对于SS浓度,屋顶径流高于路面径流。总磷TP的颗粒吸附态的污粢物对总污染物的贡献最大,对于珞面径流高达80．1％,对于屋顶径流为68．6％;其次是CODcr和BOD5,TN颗粒吸附态比重最低,通过沉积或过滤去除城市地表径流中的悬浮颗粒物,可以大大减少污粢物的含量。降雨径流中的污染物浓度远高于同期河涌水体中的污染物浓度（除TN外）,降雨径漉对河涌水中污染物输入的贡献占有相当的份额。     

雨水口截污装置对径流污染的控制效果

城市降雨径流污染对水环境造成严重危害,市政雨水口作为收集雨水的构筑物,可以改造为源头截污设施。试验采取雨水口增设截污网篮的形式,对雨水口进、出水进行了采样检测,分析结果表明:径流雨水中污染物成分复杂,在雨季初期及降雨间隔时间较长的情况下,径流污染负荷尤为明显。截污装置以物理截留功能为主,对SS去除效果较好,场降雨平均去除率为54.5%,对COD、可滤残渣等污染物的去除效果相对较差。截污装置作为一种简易净化措施,可以应用于新建、改建及扩建地区的市政雨水口,起到控制径流污染、缓解黑臭水体的功能。     

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.