硫酸盐还原颗粒污泥对Cr的吸附机理解析

以硫酸盐还原颗粒污泥作为研究对象,进行Cr的吸附容量研究及吸附等温线拟合,测定颗粒污泥中的硫化物含量、对比实验前后颗粒污泥的表面形态和微生物组成并采用傅里叶红外变换光谱(FTIR)分析颗粒污泥的表面基团。结果表明,颗粒污泥对Cr的吸附容量为6.84 mg/g,吸附过程可用Langmuir吸附等温式描述。颗粒污泥中硫化物含量达9.868 mg/g(湿重),对应每克颗粒污泥对Cr的最大吸附量可达10.69 mg;颗粒污泥表面生长大量的微生物,以杆菌为主,颗粒污泥表面丰富的微孔结构及微生物所分泌的胞外物均可有效吸附溶液中的Cr;FTIR分析结果显示,颗粒污泥中包含大量C=O、C-N及-S等基团,这些基团均可通过与C(rⅥ)或C(rⅢ)之间的静电吸附作用吸附溶液中的Cr。研究表明化学与生物吸附作用在硫酸盐还原颗粒污泥吸附溶液中的Cr过程中起到了重要的作用。     

水环境中重金属检测方法研究进展

重金属污染是水污染的主要问题之一,严重威胁水生生物的生存和人类健康。文章对近年来水环境中重金属的检测方法进行了综述,主要介绍了原子吸收光谱法、电感藕合等离子体法、原子荧光光谱法、溶出伏安法、生物酶抑制法、免疫分析法和生物化学传感器法等。列举了不同方法的灵敏度、准确性和适用范围等,并对各自优点进行了比较。     

停留时间对滴滴涕农药热处理特性的影响研究

利用高温管式炉研究停留时间对滴滴涕农药热处理特性的影响。结果表明,600℃时ηDDT在15 min内迅速增长,在15 min后稳定在85%上下;900℃时,当停留时间≥15 min,ηDDT≥99%;1 200℃时,各时段的ηDDT≥99.9%。在滴滴涕农药残渣中,DDTs在600℃和900℃时的配比随停留时间的增加变化甚微,在1 200℃时,p,p’-DDD、DDT和o,p’-DDT分别占DDTs总量的比例随时间增加明显降低,p,p’-DDE则大幅增加。在尾气中,DDTs在600℃时的配比随停留时间的增加无明显变化,DDT为主要尾气残留物质,900℃时DDTs在尾气中配比变化混乱,1 200℃时,p,p’-DDE的比例随停留时间的增长迅速增加,并成为尾气中的主要DDTs残留物质。     

Responses of protists with different feeding habits to the changes of activated sludge conditions: A study based on biomass data

Changes of protists, which were categorized into different functional groups primarily according to their feeding habits, in two full-scale municipal wastewater treatment systems experiencing sludge bulking were investigated over a period of 14 months. Protist biomass represented 3.7% to 5.2% of total biomass on average under normal sludge conditions, and the percentage increased significantly (p < 0.05) under sludge bulking conditions. The biomass of Chilodonella spp., capable of eating filamentous bacteria, tended to decrease in both systems when sludge bulking occurred, showing that the abnormal growth of filamentous bacteria did not lead to a biomass bloom of this group of protists. On the other hand, the bactivorous protists represented more than 96% of total protist biomass, and the biomass of this group, particularly the attached ciliates, increased significantly (p < 0.05) when sludge bulking occurred. The significant increase of the attached ciliates may have possibly facilitated the growth of filamentous bacteria through selectively preying on non-filamentous bacteria and further exacerbated sludge bulking. The redundancy analysis and correlation analysis results showed that the biomass changes of the attached ciliates were primarily related to the sludge volume index and to some extent related to five-day biochemical oxygen demand loading and hydraulic retention time.     

Surface clogging process modeling of suspended solids during urban stormwater aquifer recharge

Aquifer recharge,which uses urban stormwater,is an effective technique to control the negative effects of groundwater overexploitation,while clogging problems in infiltration systems remain the key restricting factor in broadening its practice.Quantitative understanding of the clogging process is still very poor.A laboratory study was conducted to understand surface physical clogging processes,with the primary aim of developing a model for predicting suspended solid clogging processes before aquifer recharge projects start.The experiments investigated the clogging characteristics of different suspended solid sizes in recharge water by using a series of one-dimensional fine quartz sand columns.The results showed that the smaller the suspended particles in recharge water,the farther the distance of movement and the larger the scope of clogging in porous media.Clogging extents in fine sand were 1 cm,for suspended particle size ranging from 0.075 to 0.0385 mm,and 2 cm,for particles less than 0.0385 mm.In addition,clogging development occurred more rapidly for smaller suspended solid particles.It took 48,42,and 36 hr respectively,for large-,medium-,and small-sized particles to reach pre-determined clogging standards.An empirical formula and iteration model for the surface clogging evolution process were derived.The verification results obtained from stormwater recharge into fine sand demonstrated that the model could reflect the real laws of the surface clogging process.     

Extraction of heavy metals from e-waste contaminated soils using EDDS

Environmental contamination due to uncontrolled e-waste recycling activities is drawing increasing attention in the world. Extraction of these metals with biodegradable chelant [S,S]-ethylenediaminedisuccinic acid (EDDS) and the factors influencing extraction efficacy were investigated in the present study. Results showed that the addition of EDDS at low pH (5.5) produced higher metal extraction than that at high pH (8.0) solution. Metal speciation analysis indicated that Cu was completely complexed with EDDS at different pH conditions with various amounts of EDDS applied. For Pb and Zn, at low EDDS dose of 0.304 mol/kg soil, they were present as Pb- and Zn-EDDS. However, at high EDDS dose of 1.26 mol/kg soil, most of Pb was bound with dissolved organic matter. Ca and Al were found to be strong competitors for trace metals to EDDS at low application dose and low pH condition.     

Occurrence of selected aliphatic amines in source water of major cities in China

The formation of toxic nitrogenous disinfection byproducts (N-DBPs), such as nitrosamines, halonitromethanes and haloacetonitriles, from reactions between chlorine/chloramine and dissolved organic nitrogen in drinking water has caused great concern with regarding public health. This study revealed the occurrence of 17 aliphatic amines, some of which have been confirmed to be the precursors of N-DBPs, in source water across China. A sensitive method based on benzenesulfonyl chloride derivatization and liquid-liquid extraction followed by GC-MS analysis was established for the simultaneous analysis of the selected amines in aqueous samples. In total, 37 source water samples from the capital cities of 20 provinces were collected for the survey. Among the 17 amines, 14 were detected with an average frequency of detection of 36%. The most relevant amines in terms of frequency and maximum concentrations detected were dimethylamine (100%, 24.82 μg/L), methylamine (78%, 0.92 μg/L), N-methylethylamine (70%, 8.84 μg/L), propylamine (59%, 10.69 μg/L), diethylamine (54%, 3.76 μg/L), N-methylbutylamine (35%, 3.07 μg/L), N-ethylpropylamine (35%, 0.52 μg/L), and piperidine (32%, 2.35 μg/L). This is the first large scale survey of the aliphatic amines occurrence in source water in the world. The wide presence of nitrosamine precursors like dimethylamine, N-methylethylamine and diethylamine, and the precursors of haloacetonitriles and halonitromethanes like methylamine and propylamine suggests that better source water management is required to ensure the safety of drinking water.     

Fractionation of residual Al in natural water treatment from reservoir with poly-aluminum-silicate-chloride (PASiC): Effect of OH/Al, Si/Al molar ratios and initial pH

An aluminum fractionation study was conducted for a surface reservoir water treatment to understand the performance of poly-aluminum-silicate-chloride (PASiC) in terms of the residual Al fractions as a function of initial pH. The coagulation performance expressed as turbidity and organic matter removal was established as supporting data. Some extra data were evaluated in terms of the residual Al ratio of the composite PASiC coagulant. The main residual Al sources were the Al fractions derived from the use of PASiC. The turbidity and organic matter removal ability was optimal at initial pH 6.00-7.00, while the concentrations of various residual Al species and the residual Al ratio of PASiC were minimal at an initial pH range of 7.00-8.00. Under the conditions of OH/Al molar ratio = 2.00 and Si/Al molar ratio = 0.05, PASiC had superior coagulation performance and comparatively low residual Al concentrations. The Al fraction in the composite PASiC coagulant seldom remained under such conditions. Experimental data also indicated that the suspended (filterable) Al fraction was the dominant species, and organic-bound or organo-Al complex Al was considered to be the major species of dissolved Al in water treated by PASiC coagulation. Additionally, the dissolved inorganic monomeric Al species dominated the dissolved monomeric Al fraction.     

土地督察对土地市场化的影响效果评估

为评估土地督察对土地市场化的影响,论文把目标分解为两个问题:即土地督察制度的实施是否对土地市场化程度产生影响;如果有影响,影响的效果如何。论文收集了2003—2009年的省级面板数据,基于固定效应和随机效应模型估计了土地督察对土地市场化的影响。通过相关检验,采用了固定效应模型的估计结果,并在模型估计的基础上,对影响效果进行了评价。结果表明:①土地督察对土地市场化的发展有积极的促进作用,2007—2009年专项督察覆盖度每提高1%,约能促进土地市场化程度提升0.14%,例行督察覆盖度每提高1%,约能促进土地市场化程度提升1.12%;②通过实施专项督察,2007—2009年全国土地市场化程度分别提升了2.06%、 0.19%和0.55%,通过实行例行督察,2008—2009年全国土地市场化程度分别提升5.01%和12.47%;③2007—2009年通过开展土地督察,全国土地市场化程度分别提高了2.04%、 5.21%和13.02%。     

银川平原主要湖泊湿地水环境现状调查与分析

为了掌握和了解银川平原主要湖泊湿地的水质环境状况,对宁夏沙湖、鸣翠湖、星海湖、阅海湖、鹤泉湖等湿地开展了水质现状调查和分析研究,结果表明,这些湖泊湿地都受到污染,沙湖、星海湖和鸣翠湖的水质受到轻度污染,水质根据地表水环境质量标准分类为IV类,鹤泉湖和阅海湖的水质受到中度污染,水之类别为V类。该研究为湿地资源保护与合理利用提供科学依据,对宁夏经济协调发展提供科技支撑。