Effective degradation of tetracycline by mesoporous Bi<Subscript>2</Subscript>WO<Subscript>6</Subscript> under visible light irradiation

Bi₂WO₆ was synthesized with a hydrothermal method at different pHs and used for the degradation of tetracycline (TC) in water. The mesoporous Bi₂WO₆ prepared at pH 1 (BWO-1) displayed the highest adsorption and degradation capacity to TC due to its large surface area and more efficient capacity to separate photogenerated electrons and holes. 97% of TC at 20 mg·L^?1 was removed by BWO-1 at 0.5 g·L^?1 after 120 min irradiation under simulated solar light. Only 31% of the total organic carbon (TOC) was removed after 360 min irradiation although the TC removal reached 100%, suggesting that TC was mainly transformed to intermediate products rather than completely mineralized. The intermediates were identified by high-performance liquid chromatography-time of flight-mass spectrometry (HPLC-TOF-MS) and possible photodegradation pathways were proposed.     

颗粒污泥膜生物反应器同步硝化反硝化

在本实验条件下,厌氧-好氧序批式颗粒污泥膜生物反应器(GMBR)处理人工配水,结果表明,GMBR具有良好的有机物去除及脱氮效果,当进水TOC及氨氮分别为160.9～308.4mg/L、29.8～83.6mg/L时,GMBR的TOC、氨氮及总氮去除率分别为65.7%～98.6%、85.4%～98.9%及66.1%～95.1%.对于GMBR典型周期TOC、胞内聚β-羟基丁酸(PHB)、氨氮、硝酸盐氮及亚硝酸盐氮变化进行分析,结果表明,有机物主要在厌氧阶段去除并以胞内多聚物PHB形式储存,氨氮在好氧阶段经由同步硝化反硝化(SND)去除,并且反硝化碳源主要来自胞内储存物质PHB.以外源溶解性基质及胞内储存物质为碳源的批式实验表明,以外源基质为碳源的缺氧反硝化速率为胞内储存物质的4.2倍;以外源基质及胞内PHB为碳源的好氧SND效率分别为49.9%、82.5%.胞内储存物质PHB的慢速降解特性使得硝化与反硝化过程能够同步进行.     

淀粉废水处理方法综述

由于淀粉加工企业分布广且废水COD浓度高,淀粉废水处理方法的研究越来越受到重视。就目前国内外淀粉废水的各种处理方法和工艺进行综述,重点介绍了淀粉废水处理方面的最新研究成果,并介绍了废水资源化的一些途径。     

A new strategy for obtaining highly concentrated phosphorus recovery solution in biofilm phosphorus recovery process

Recovery of phosphorus（P） from wastewater is of great significance for alleviating the shortage of P resources. At present, the P recovery process is faced with the problem of excessive organic carbon consumption when obtaining a P-concentrated recovery solution. This study proposed a new strategy to obtain a more highly concentrated P recovery solution with minimal carbon consumption by strengthening the P storage capacity of the biofilm. A biofilm sequencing batch reactor（BSBR） process was mod...     

Control of diffuse P-pollutants by multiple buffer/detention structures by Yuqiao Reservoir, North China

A case study on the transport process of agricultural diffuse P-pollutants was conducted in an experimental watershed locating in the north bank of Yuqiao Reservoir during 2001 and 2002. It was found that diversified artificial and natural buffer/detention landscape structures distributing along the ephemeral stream channel in this watershed played an important role of pollutants removal on downstream water quality, especially they have control effect on the diffuse P-pollutants transport process. Surface flow velocity was reduced sharply after passing through theses tructures. During continuous runoff events, the removal rate of TSS, TP, TDP, DRP by the whole system were 66.7%, 60.7%, 48.4%, and 43.3%, respectively. During discontinuous runoff events, removal rate of pollutants by the whole system was higher due to there was no or little surface water and pollutants exported from the watershed, of which removal rate of pollutants all exceeded 99%. The statistical analysis results of runoff events( n=8) indicated that dry pond was the steadiest structure for controlling diffuse P-pollutants export.     

Effect of recent climate change on Arctic Pb pollution: a comparative study of historical records in lake and peat sediments

Historical changes of anthropogenic Pb pollution were reconstructed based on Pb concentrations and isotope ratios in lake and peat sediment profiles from Ny-?lesund of Arctic. The calculated excess Pb isotope ratios showed that Pb pollution largely came from west Europe and Russia. The peat profile clearly reflected the historical changes of atmospheric deposition of anthropogenic Pb into Ny-?lesund, and the result showed that anthropogenic Pb peaked at 1960s-1970s, and thereafter a significant recovery was observed by a rapid increase of (206)Pb/(207)Pb ratios and a remarkable decrease in anthropogenic Pb contents. In contrast to the peat record, the longer lake record showed relatively high anthropogenic Pb contents and a persistent decrease of (206)Pb/(207)Pb ratios within the uppermost samples, suggesting that climate-sensitive processes such as catchment erosion and meltwater runoff might have influenced the recent change of Pb pollution record in the High Arctic lake sediments.     

混凝吸附及化学氧化深度处理焦化废水

以蒙脱石、凹凸棒石、次氯酸钙和PAC、PAM为基本材料,对焦化废水二级生化出水进行深度处理。实验结果表明：蒙脱石与凹凸棒石以4：1的比例配合使用,可明显提高焦化废水中COD和色度去除率;采用次氯酸钙作为氧化剂,可进一步提高焦化废水的脱色率和COD去除率,处理间差异达到极显著和显著水平;去除COD的最优实验条件为：粘土矿物（蒙脱石：和凹凸棒石=4：1）添加量4．0g／L、氧化剂（次氯酸钙）添加量1．0g／L、絮凝剂（聚合氯化铝：聚丙烯酰胺=15／1）添加量0．15g／L,处理后色度去除率达到97．0％,COD去除率达到69．1％;脱色的最优实验条件为：粘土矿物添加量4．0g／L、氧化剂添加量1．0g／L、絮凝剂添加量0．2g／L,处理后色度去除率达到98．5％,COD去除率达到66．4％。     

农村市场化对农户耕地流转的影响——以沪苏皖农户调查为例

随着市场经济体制的全面确立,农村市场化与农户土地利用行为的关系越发紧密。为揭示农村市场化对农户耕地流转行为的影响,围绕农产品销售市场和土地流转市场两方面,运用农户调查法和Heckman两阶段模型进行分析。结果显示：耕地流转费用和农产品销售价值的高低决定着农户土地预期及农业效益的实现程度,对耕地流转概率和流转面积产生了显著影响。同一要素对流入和流出的推拉作用往往是相反的。农户特征、耕地资源和地区差异等要素对耕地流转也产生了明显的影响,与流转动因相一致。由于目前农村土地流转市场和农产品市场尚不健全,积极发展现代农业,推进规模经营,规范土地流转,有助于改善农户福利,优化农业土地利用结构     

江西赣江中下游淡水双壳类分布与丰度

淡水双壳类是淡水生物群落的重要组成部分,在河流等生态系统中有重要功能。2010年11月至2011年2月对江西赣江中下游淡水双壳类的种类、分布及丰度进行了调查,共采集到双壳类34 种及亚种,隶属3科14 属。中游双壳类有8种,优势种为圆顶珠蚌和河蚬;下游干流有34种,优势种为圆顶珠蚌、河蚬、洞穴丽蚌和中国尖嵴蚌。赣江中游、下游干流双壳类的平均密度和生物量分别为64±91 ind./m2、210±254 g/m2,267±441 ind./m2、2123±3148 g/m2。从赣江中游到下游干流双壳类物种多样性、密度和生物量均呈现增加的趋势     

Gene Cloning and Characterization of a Poly(<Emphasis Type="SmallCaps">l</Emphasis>-Lactic Acid) Depolymerase from <Emphasis Type="Italic">Pseudomonas</Emphasis> sp. Strain DS04-T

A gene encoding a poly(l-lactic acid) (PLA) depolymerase from Pseudomonas sp. strain DS04-T was cloned and overexpressed in Escherichia coli. The recombinant PLA depolymerase with a molecular weight of 19.2 kDa was purified to homogeneity. The optimum pH and temperature of the PLA depolymerase are 8.5 and 60 °C, respectively. K⁺, Ca²⁺ and Ni²⁺ enhance the enzyme activity, while Na⁺, Zn²⁺, Mg²⁺, Cu²⁺, Fe²⁺, Mn²⁺ and Co²⁺ inhibit it. The inhibition of different chemicals on the PLA depolymerase activity were examined, in which EDTA was found to have a significantly inhibitory effect. The main degradation product of the depolymerase is identified as lactic acid monomer by mass spectrometric analysis. Physicochemical properties, substrate specificity and sequence analysis indicated that PME is a new type of PLA depolymerase.