Spatial and seasonal variations of the contamination within water body of the Grand Canal, China

To delineate the character of contaminations in the Grand Canal, China, a three-year study (2004-2006) was conducted to investigate variations the water quality in the canal. Results showed that the variation of water quality within the Grand Canal was of there is remarkable spatial and seasonal heterogeneity regarding water quality within the Canal. Values of contaminants in dry-season were obviously higher than those in wet-season. Sites influenced strongly by industry and urbanization showed higher contents of nutrients and lower levels of dissolved oxygen in water body; moreover these sites were severely polluted by dissolved metals with the contents of cadmium, chromium and copper exceeding the Criteria Maximum Concentration (CMC), US EPA. Multivariate statistical analysis suggested nutrient and dissolved metals pollution was the dominant environmental problems within the Canal. Anthropogenic influences played a dominant role in the character of contaminations in the Grand Canal.     

异波折板水解酸化-A2O一体化反应器实验研究

设计了异波折板水解酸化-A2O一体化反应器,进行生活污水处理的实验研究。10个月的实验结果表明,系统的最佳水力停留时间（HRT）为8 h时,最适COD进水浓度为240-100mg/L,最佳混合液回流比（r）-污泥回流比（R）为250%-100%。控制反应器于以上运行参数下,25±2℃所对应的COD、TN和TP去除率分别为96.84%、67.55%和81.92%。当温度降至7℃时,其COD、TP和TN分别降至86.35%、50.25%和65.68%。基于实验分析结果,阐明了一体化反应器高效性的机理在于异波折板水解酸化段具有高效传质特性和A2O段具有复合式活性污泥-接触氧化好氧池的特点。     

支持向量机在城市震后火灾损失预测中的应用

针对地震火灾的复杂性和多变性的特点,在综合分析了各种震后火灾损失预测方法的基础上,提出了基于支持向量机的城市震后火灾损失预测模型。以地震火灾的历史资料为依据,建立学习样本和测试样本,并与BP神经网络预测方法相比较,验证了其可行性,也为其它自然灾害的损失预测提供了简单、有效的方法。     

城镇圩区排涝模数计算方法及其与河道调蓄库容关系研究

农业圩区原有的排涝模数计算方法已不适用于城镇圩区.针对城镇圩区的排涝特殊性,通过分析排涝计算的原理,充分考虑圩区内河道的调蓄能力,得到适应城镇圩区排涝计算的方法.以南京市江宁区为例,对城镇圩区的排涝模数进行计算,得到排涝模数与调蓄库容之间的定量关系.     

活性炭/聚丙烯腈纤维对溶液中的甲基橙染料吸附动力学研究

采用自制添加活性炭的聚丙烯腈纤维为吸附剂,吸附染料甲基橙溶液,考察了活性炭含量、温度及溶液pH值等因素对纤维吸附染料甲基橙吸附量和吸附速率的影响.结果表明,活性炭/聚丙烯腈纤维吸附甲基橙染料符合表观二级动力学方程.吸附过程的限速步骤为甲基橙染料向活性炭/聚丙烯腈纤维中活性炭颗粒内部微孔扩散,自制的活性炭/聚丙烯腈纤维对甲基橙染料具有较大的吸附容量和较快的吸附速率,可作为甲基橙等染料废水治理的理想材料.     

Biodiesel production from waste oil feedstocks by solid acid catalysis

Biodiesel is a non-toxic and biodegradable substitute for petroleum-based diesel. However, it is impractical to use refined edible oils to produce biodiesel due to its high cost and priority for food products, especially in China, while waste oils with high free fatty acids (FFAs) can be considered as the raw materials. In the present work, a solid acid catalyst comprising SO₄²⁻/TiO₂–SiO₂ was prepared, characterized and studied for its activity for the production of biodiesel from several low cost feedstocks with high FFAs. The solid acid catalyst can be recycled, easily removed and can simultaneously catalyze esterification and transesterification. The influence of reaction parameters was studied, and the optimized reaction parameters are reaction temperature 200 °C, molar ratio of methanol to oil 9:1 and catalyst concentration 3 wt.%. The catalyst showed good stability. A continuous process for biodiesel production from cheap raw feedstocks was proposed, and a 10,000-tonnes/year biodiesel production demonstration plant has been built.     

Rhamnolipid morphology and phenanthrene solubility at different pH values

The effect of pH and rhamnolipids on the solubility of phenanthrene was investigated in a sand-water system. Batch phenanthrene solubilization experiments in this system showed that the highest phenanthrene solubility occurred at pH 5 in the presence of 240 and 150 mg L(-1) rhamnolipids. As the pH was increased from 5 to 7, the apparent solubility of phenanthrene decreased and then stabilized from pH 7 to 8. At pH 4, a dramatic decrease in phenanthrene solubility was observed. This result is in contrast to previous findings obtained in an aqueous system without soil particles. To investigate the reason for this decrease, the critical micelle concentrations (CMCs) were measured in the presence or absence of sand particles, and the maximum amount of sorbed biosurfactant at each pH was calculated based on the differences of the two CMC values. More rhamnolipid molecules were lost by the sorption into sand particles at pH 4 than at other pH values; this explains the dramatic decrease of solubility at pH 4 in the sand-water system. To confirm the explanation for the different solubilizing capacity that results from the structural change of biosurfactant aggregate, cryo-transmission electron microscopy was used. Micrographs showed that the rhamnolipid morphology changed from large lamellar sheets, to vesicle, and then to micelle as the pH increased. The large and multilamellar vesicles at pH 5 were considered to be the most effective structure for the solubilization of phenanthrene.     

Application of a magnetotactic bacterium, Stenotrophomonas sp. to the removal of Au(III) from contaminated wastewater with a magnetic separator

In this study, the feasibility of applying a magnetotactic bacterial isolate (MTB), Stenotrophomonas sp. to the removal of Au(III) was investigated. Biosorption experiments showed that Au(III) biosorption capacity exhibited no significant difference in the initial pH range of 1.0-5.5, while decreased more significantly in the initial pH range of 5.5-13.0. Langmuir isotherm indicated that the maximum Au(III) biosorption capacity of Stenotrophomonas sp. were 506, 369 and 308 mg g(-1) dry weight biomass at the initial pH values of 2.0, 7.0 and 12.0, respectively. Thiourea was proved to be an effective desorbent to recover Au from the MTB biomass and 91% Au adsorbed on the biomass could be recovered at equilibrium when the thiourea concentration was 0.8M. The magnetic separator developed by our research team used for separating Au loaded MTB biomass showed high separation efficiency, with 100% biomass removed at the magnetic intensity of 1200 Gs in 180 min. The analyses from FTIR and XRD further confirmed that the reduction of Au(III) to Au(0) by the reductants on the MTB biomass occurred, and the deposition of nano-crystal Au(0) particles, ranging from 24.7 to 31.4 nm, could be estimated on the biomass surface.     

Catalytic reduction of sulfur dioxide with carbon monoxide over tin dioxide for direct sulfur recovery process

SO(2) reduction by CO over SnO(2) catalyst was studied in this work. The parameters were the reaction temperature, space velocity (GHSV) and [CO]/[SO(2)] molar ratio. The optimal temperature, GHSV and [CO]/[SO(2)] molar ratio were 550 degrees C, 8000 h(-1) and 2.0, respectively. Under these conditions, the SO(2) conversion and sulfur selectivity were about 78% and 68%, respectively. The following reaction pathway involving two mechanisms was proposed in SO(2) reduction by CO over SnO(2) catalyst: in the first step involving Redox mechanism, the elemental sulfur was produced by the mobility of the lattice oxygen between SO(2) and SnO(2) surface. In the second step, COS was formed by the side reaction between elemental sulfur and CO or metal sulfide and CO. In the third step involving COS intermediate mechanism, the abundant elemental sulfur was produced by the SO(2) reduction by COS which was produced in the second step and was more effective reducing agent than CO.