基于中性盐提取的土壤重金属固液分配与自由态金属离子浓度测定

采用0.01mol·L-1CaCl2、0.002mol·L-1Ca(NO3)2和纯水(UPW)3种常用提取剂对我国南方两种典型农田重金属污染土壤进行提取试验.同时,应用土壤重金属固液分配多表面模型来预测提取液中重金属含量,结合道南膜技术(DMT)测定Ca(NO3)2提取液中自由态金属离子浓度,并与ECOSAT模型计算值进行比较.结果表明,提取剂中Ca2+浓度增加能显著提高土壤重金属溶出率,而提取液pH、溶解态有机碳(DOC)浓度却随溶液Ca2+浓度增加而降低.多表面模型(Multi-Surface Model)对大部分提取液金属浓度有较好的预测效果,部分土样提取液Cu、Pb、Zn浓度的预测效果较差.DMT测定的Ca(NO3)2提取液自由态重金属浓度与模型计算值较为一致,能够较准确地测定土壤溶液自由态重金属离子浓度.     

水源地藻类及藻毒素同时去除的效果及机制分析

利用组合载体对太湖梅梁湾水源地水体中藻类及藻毒素的同时去除试验表明:检测水源地水体中藻量、Chl-a、TMC的含量各为(31.67～78.27)×106个.L-1、32.58～102.67μg·L-1、1.79～11.97μg·L-1.在水力停留时间为7d、组合载体的密度为13.1%的条件下,组合载体AP对藻量的平均去除率达到了59.78%,对Chl-a的平均去除率达到了80.82%,对TMC-LR、TMC-RR、EMC-LR、EMC-RR的降解率最高能达到99.73%、97.10%、100%、75.44%.对其去除机制的研究表明,组合载体AP对总细菌的富集能力达到了8.3×1011～35.6×1011cells.g-1,比湖水本底值中细菌的总数高出了8～9个数量级.对除藻及藻毒素过程中的优势菌种,经过培养、分离,考察其形态、生理生化特性,利用聚合酶链反应(PCR)、16S rRNA序列分析技术,经鉴定确认该优势菌株为假单胞菌属(Pseudomonas sp.)和芽孢杆菌(Bacillussp.).组合载体AP上富集的大量微生物,它们的协同降解作用是去除藻及藻毒素的主要作用机制.     

亚硝酸盐积累对A~2O工艺生物除磷的影响

常温条件下,通过控制好氧区DO浓度为0.3～0.5 mg/L,同时增大系统内回流比以降低系统好氧实际水力停留时间(actual hydraulic retention time,AHRT),在处理低C/N比实际生活污水的A2O工艺中成功启动并维持了短程硝化反硝化.但随着系统出水亚硝酸盐含量的升高,系统对磷的去除效果逐渐恶化.当好氧区亚硝酸盐浓度19 mg/L时,系统出水磷浓度大于进水磷浓度,系统处于净释磷状态.通过对原水COD浓度、反应区温度、pH值、游离亚硝酸浓度(free nitrous acid,FNA)等分析,表明碳源不足及短程硝化引起的亚硝酸盐积累影响了聚磷菌厌氧释磷和好氧吸磷;尤其是好氧区较高的FNA浓度(HNO2-N 0.002～0.003 mg/L)对聚磷菌好氧吸磷的抑制是导致系统除磷效果恶化的直接原因.通过外投碳源提高原水COD浓度,提高了聚磷菌厌氧释磷合成PHA的能力;同时增强了系统的反硝化能力,降低好氧区亚硝酸盐浓度,从而降低FNA对聚磷菌好氧吸磷的抑制程度,系统的除磷性能可迅速恢复;系统对磷的去除率可达96%以上.     

A~2/O-曝气生物滤池工艺处理低C/N比生活污水脱氮除磷

以低C/N比实际生活污水为研究对象,重点考查了A2/O-曝气生物滤池生化系统的脱氮除磷特性.同时,考虑到A2/O工艺的主要功能是除磷及反硝化,而曝气生物滤池则以硝化为目的.因此,通过缩短A2/O的泥龄,可将硝化过程从A2/O中分离出去,让曝气生物滤池完成硝化,实现硝化菌和聚磷菌的分离,并解决了硝化菌和聚磷菌泥龄之间的矛盾.试验结果表明,该生化系统可实现有机物、氮和磷的同步去除.在平均C/N比为4.2,内回流比R为250%的条件下,平均进水COD、TN、TP分别为239.9、57.3和5.1mg·L-1,平均最终出水COD、TN、TP分别为34.1、13.3和0.1mg·L-1,去除率分别为85.8%、76.9%和98.3%.曝气生物滤池对氨氮几乎保持了100%的去除率.序批试验表明,反硝化聚磷菌占聚磷菌的比例为40.5%.     

组合人工湿地对城镇污水处理厂尾水中有机物的去除特征研究

采用物理分级和三维荧光光谱法,研究了组合人工湿地对城镇污水处理厂尾水中不同形态有机物的去除特征.结果表明,组合人工湿地对污水处理厂尾水具有较好的深度处理效果,出水水质基本可以达到国家地表水环境质量标准(GB38382-2002)Ⅲ或Ⅳ类水标准.组合人工湿地处理系统对尾水中CODCr和BOD5总体去除率分别达到35.2%和44.3%,对尾水中总有机碳(TOC)、溶解性有机碳(DOC)、颗粒有机碳(POC)的平均去除率分别为46.9%、45.9%、48.3%.组合人工湿地系统不同单元对尾水中有机物的去除贡献率存在差异,其中,潜流湿地单元对尾水中CODCr和BOD5及其不同组分有机碳的去除效率较高.试验期间,由于藻类滋生,表流湿地单元出水中有机物含量波动较大,去除效果明显降低,藻类被打捞后,出水水质明显改善.三维荧光光谱分析结果显示,各个处理单元取样点的水样三维荧光光谱均出现4个明显的荧光峰.人工湿地各单元出水溶解性有机质(DOM)中,类蛋白和类腐殖酸物质含量较高,类富里酸物质含量较低.人工湿地对类蛋白和类腐殖酸物质有较强的去除作用.     

序批式颗粒污泥系统中磷的变化和去向分析

在实验室序批式活性污泥法(SBR)处理系统中以普通活性污泥为接种污泥,采用厌氧-好氧的运行方式提高系统的除磷效果.同时培养颗粒污泥,并对系统中磷的变化和去向进行分析.结果表明,整个试验共运行146 d,成熟颗粒污泥平均粒径为603μm,污泥体积指数(SVI)约为30 mL.g-1,COD去除率可达90%,磷的去除率可达95%左右.颗粒污泥系统除厌氧放磷和好氧聚磷以外,还存在明显的污泥颗粒积磷现象.磷的去除途径主要为:系统排泥(出水悬浮物和专门排泥)和污泥积磷.由厌氧末期颗粒污泥的X射线衍射(XRD)分析结果可知,化学沉淀是污泥积磷的一种重要方式,大量的金属离子会与磷形成无机盐沉积在污泥颗粒上.     

添加剂和湿法除尘主要参数对炭黑去除效率的影响

选取十六烷基三甲基溴化胺(CTAB)、十二烷基苯磺酸钠(SDBS)、月桂醇聚氧乙烯(9)醚(AEO-9)和壬基酚聚氧乙烯醚(OP-10)4种表面活性剂配制成吸收液,采用伞形罩洗涤器对燃煤窑炉黑烟进行湿法除尘净化实验,探讨添加剂种类、入口含尘浓度(Cin)、入口风速(u)和液气比(L/G)参数的不同对炭黑(BC)去除效率(η)的影响,结合压降(ΔP,Pa)的变化提出高效脱黑的可行方案.结果表明,在实验条件同为Cin=2g·m-3、u=12m·s-1和L/G=0.2L·m-3条件下,4种吸收液脱黑效果差别不大,AEO-9吸收液具有略明显的优势,炭黑去除效率可达到99.5%(0.06mmol·L-1,AEO-9);在u=12m·s-1和L/G=0.2L·m-3条件下,Cin=5g·m-3时更利于洗涤器对黑烟的净化,AEO-9吸收液的炭黑去除效率近乎100%,ΔP变化不大;入口风速的变化对炭黑去除效率和压降的影响比较明显,当Cin和L/G分别为2g·m-3、0.2L·m-3时,最佳入口风速为12～14m·s-1,炭黑去除效率保持在99%以上;最佳操作液气比可控制在0.2～0.4L·m-3.     

An autotrophic nitrogen removal process：Short-cut nitrification combined with ANAMMOX for treating diluted effluent from an UASB reactor fed by landfill leachate

A combined process consisting of a short-cut nitrification (SN) reactor and an anaerobic ammonium oxidation upflow anaerobic sludge bed (ANAMMOX) reactor was developed to treat the diluted effluent from an upflow anaerobic sludge bed (UASB) reactor treating high ammonium municipal landfill leachate.The SN process was performed in an aerated upflow sludge bed (AUSB) reactor (working volume 3.05 L),treating about 50% of the diluted raw wastewater.The ammonium removal efficiency and the ratio of NO 2 N to NOx-N in the effluent were both higher than 80%,at a maximum nitrogen loading rate of 1.47 kg/(m 3 ·day).The ANAMMOX process was performed in an UASB reactor (working volume 8.5 L),using the mix of SN reactor effluent and diluted raw wastewater at a ratio of 1:1.The ammonium and nitrite removal efficiency reached over 93% and 95%,respectively,after 70-day continuous operation,at a maximum total nitrogen loading rate of 0.91 kg/(m 3 ·day),suggesting a successful operation of the combined process.The average nitrogen loading rate of the combined system was 0.56 kg/(m 3 ·day),with an average total inorganic nitrogen removal efficiency 87%.The nitrogen in the effluent was mostly nitrate.The results provided important evidence for the possibility of applying SN-ANAMMOX after UASB reactor to treat municipal landfill leachate.     

Evaluation of mercury speciation and removal through air pollution control devices of a 190 MW boiler

Air pollution control devices (APCDs) are installed at coal-fired power plants for air pollutant regulation. Selective catalytic reduction (SCR) and wet flue gas desulfurization (FGD) systems have the co-benefits of air pollutant and mercury removal. Configuration and operational conditions of APCDs and mercury speciation a ect mercury removal e ciently at coal-fired utilities. The Ontario Hydro Method (OHM) recommended by the U.S. Environmental Protection Agency (EPA) was used to determine mercury speciation simultaneously at five sampling locations through SCR-ESP-FGD at a 190 MW unit. Chlorine in coal had been suggested as a factor a ecting the mercury speciation in flue gas; and low-chlorine coal was purported to produce less oxidized mercury (Hg2+) and more elemental mercury (Hg0) at the SCR inlet compared to higher chlorine coal. SCR could oxidize elemental mercury into oxidized mercury when SCR was in service, and oxidation e ciency reached 71.0%. Therefore, oxidized mercury removal e ciency was enhanced through a wet FGD system. In the non-ozone season, about 89.5%–96.8% of oxidized mercury was controlled, but only 54.9%–68.8% of the total mercury was captured through wet FGD. Oxidized mercury removal e ciency was 95.9%–98.0%, and there was a big di erence in the total mercury removal e ciencies from 78.0% to 90.2% in the ozone season. Mercury mass balance was evaluated to validate reliability of OHM testing data, and the ratio of mercury input in the coal to mercury output at the stack was from 0.84 to 1.08.     

Ecotoxicological effects of polycyclic musks and cadmium on seed germination and seedling growth of wheat (Triticum aestivum)

Single and joint toxic e ects of polycyclic musks including 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta[g]-2- benzopyran (HHCB) and 7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronapthalene (AHTN) and cadmium (Cd) on seed germination and seedling growth of wheat (Triticum aestivum) were investigated. The results showed that the toxicity sequence of HHCB toxic to wheat seed germination and seedling growth was similar to that of AHTN, that is, germination rate > shoot elongation > root elongation, while the toxicity of Cd was in the sequence of root elongation > shoot elongation > germination rate, according to the LC50 and EC50 values. It is suggested that polycyclic musks and Cd had di erent toxicological mechanisms. Root and shoot elongation of wheat might be good bioindicators for the contamination of polycyclic musks and Cd in soil. The mixture of polycyclic musks and Cd had synergistic e ects on T. aestivum according to the equi-toxic mixture approach when root elongation was selected as the toxicological endpoint. Thus, the joint toxicity of HHCB and Cd was significantly higher than the single toxicity of HHCB or Cd, which was also confirmed by the EC50 mix value of the mixture (EC50 mix = 0.530 TUmix). The EC50 mix value of the mixture of AHTN and Cd was 0.614 TUmix, which indicated that the mixture toxicity was strengthened when AHTN coexisted with Cd.