废水处理生物流化床中O_2传递特性的研究

本文分析了废水生物处理三相流化床中氧气传递的过程及规律。指出氧气在三相流化床中的传递由气液传质与液固传质两部分组成，以完全混合流为特征的流化床内氧气在液相中可迅速实现平衡，控制步骤决定于氧气在生物相中的传质。保持一定的生物膜厚度及稳定进水基质浓度有利于氧气在生物相中的传质与吸收同时提高水处理效率。     

生物流化床的动力学研究进展

生物流化床在污水处理中较传统的处理方法有明显的优势,目前研究的方向主要有特定污染物的处理、传质研究、流化床动力学研究和生物流化床的工业化应用。生物流化床动力学研究仍制约着其工业化应用。文章对生物流化床动力学研究中所需参数的测量技术及生物流化床中载体颗粒流动规律的研究状况进行了介绍,并简述了在生物流化床动力学研究基础上对流化床的改进研究。通过对生物流化床研究现状的分析,总结了生物流化床放大存在的问题,对生物流化床的工业应用进行了展望。     

水处理新课题——膜生物流化床

膜生物反应器是通过膜技术强化生物反应器的水处理新技术,具有出水水质好、占地面积少和便于自动化控制等优点,但它存在膜污染和能耗高的缺陷;三相生物流化床具有处理效率高、容积负荷大、传质速度快等优点,但它同样也存在出水悬浮物浓度高和载体易流失的缺陷,将膜分离技术和三相生物流化床有机结合是水处理领域的一个新课题.笔者在讨论膜生物反应器和生物流化床优缺点的基础上,探讨了结合后的膜生物流化床在膜污染、能耗、微生物活性等方面的优势及特点.     

生物流化床中生物膜特性与反应器效率的关系

综述了生物流化床处理有机废水时生物膜的特性及其对反应器效率的影响。包括反应器中生物膜的形成及影响生物膜形成的因素；生物膜的活性及膜厚，基质浓度和不同种群微生物在生物膜中的分布对其活性的影响；生物膜的传质特性，生物膜厚度与反应器效率的关系；生物膜的脱膜及其数学模型；提出了生物流化床今后的研究重点。     

生物流化床工艺处理生活污水实验的灰色关联分析

采用灰色关联分析理论，阐述了生物流化床工艺处理生活污水实验的灰色关联分析方法，给出了其算法并编制了相关的程序，对实验中的主要条件：填料填充量、水力停留时间及污泥回流比对污水COD、NH3－N去除率的影响程度进行了研究，结果表明各因素的影响强弱顺序依次为：水力停留时间＞污泥回流比＞填料填充量。分析结果对生物流化床反应器的实际运行具有指导意义。     

流化床工艺在水处理中的应用研究进展

流化床工艺是一种工程应用前景广阔的处理技术,近年来该技术备受水处理研究者的青睐。已经研究出了多种反应器结构和工艺组合,如鸟粪石结晶流化反应器、三相生物流化床,具有结构紧凑、反应速度快,易于操作的优点。根据废水中污染物的去除机理将流化床归为流化床结晶反应器和流化床生物反应器两大类,论述该工艺在含磷、含氟、含硫废水,印染废水,农药废水及其他工业废水中的应用研究现状,展望了流化床反应器的发展趋势。     

内循环生物流化床反应器载体挂膜特性的研究

分别考察了水力停留时间，反应器结构，接种污泥量及载体粒径等因素对内循环三相生物流化床反应器载体挂膜的影响。试验结果表明，较短的停留时间，较小的内循环速度，较少的接种污泥量及较小粒径的载体有利于反应器的快速挂膜启动。     

生物流化床去除水中DBPs先质的实验研究

对生物流化床处理水中腐殖酸这一形成ＤＢＰｓ的重要先质进行了实验研究，分析探讨了水力停留时间，水温，ｐＨ值和曝气量对稳态出水水质的影响。并在实验基础上，对生物流化床的操作条件进行了优化。     

焦化废水生物流化床系统脱氮中试研究

以厌氧流化床、缺氧流化床作生物反应器 ,聚合物多孔高分子颗粒作微生物固定化载体 ,采用厌氧 缺氧 好氧工艺进行了焦化废水处理中试研究。结果表明 :当系统稳定运行时 ,进水NH3 N、CODCr、酚平均浓度为 5 39 5mg L、14 88mg L、2 4 7 7mg L时 ,出水NH3 N、CODCr酚平均浓度分别为 14 3mg L、2 5 2 4mg L、0 2mg L ;厌氧流化床、缺氧流化床反应器中存在厌氧氨氧化反应 ,在这 2个阶段NH3 N分别去除 9 8%和 3 3%。该生物流化床系统脱氮技术对现有焦化废水活性污泥法处理系统的改造具有指导意义     

废水生物流化床处理技术现状

介绍了应用生物流化床处理废水的研究、技术进展以及生物流化床的分类。重点介绍了一些新型反应器的操作原理和结构特点,并指出了今后生物流化床应重点研究的方向。     

Toxic effects of acetochlor, methamidophos and their combination on nifH gene in soil

Toxic effects of two agrochemicals on nifH gene in agricultural black soil were investigated using denaturing gradient gel electrophoresis （DGGE） and sequencing approaches in a microcosm experiment. Changes of soil nifH gene diversity and composition were examined following the application of acetochlor, methamidophos and their combination. Acetochlor reduced the nifH gene diversity （both in gene richness and diversity index values） and caused changes in the nifH gene composition. The effects of acetochlor on nifH gene were strengthened as the concentration of acetochlor increased. Cluster analysis of DGGE banding patterns showed that nifH gene composition which had been affected by low concentration of acetochlor （50 mg/kg） recovered firstly. Methamidophos reduced nifH gene richness that except at 4 weeks. The medium concentration of methamidophos （150 mg/kg） caused the most apparent changes in nifH gene diversity at the first week while the high concentration of methamidophos （250 mg/kg） produced prominent effects on nifH gene diversity in the following weeks. Cluster analysis showed that minimal changes of nifH gene composition were found at 1 week and maximal changes at 4 weeks. Toxic effects of acetochlor and methamidophos combination on nifH gene were also apparent. Different nifH genes （bands） responded differently to the impact of agrochemicals： four individual bands were eliminated by the application of the agrochemicals, five bands became predominant by the stimulation of the agrochemicals, and four bands showed strong resistance to the influence of the agrochemicals. Fifteen prominent bands were partially sequenced, yielding 15 different nifH sequences, which were used for phylogenetic reconstructions. All sequences were affiliated with the alpha- and beta-proteobacteria, showing higher similarity to eight different diazotrophic genera.     

Arsenic uptake by arbuscular mycorrhizal maize （Zea mays L.） grown in an arsenic-contaminated soil with added phosphorus

The effects of arbuscular mycorrhizal (AM) fungus (Glomus mosseae) and phosphorus (P) addition (100 mg/kg soil) on arsenic (As) uptake by maize plants (Zea mays L.) from an As-contaminated soil were examined in a glasshouse experiment.Non-mycorrhizal and zero-P addition controls were included.Plant biomass and concentrations and uptake of As,P,and other nutrients,AM colonization,root lengths,and hyphal length densities were determined.The results indicated that addition of P significantly inhibited root colonization and development of extraradical mycelium.Root length and dry weight both increased markedly with mycorrhizal colonization under the zero-P treatments,but shoot and root biomass of AM plants was depressed by P application.AM fungal inoculation decreased shoot As concentrations when no P was added,and shoot and root As concentrations of AM plants increased 2.6 and 1.4 times with P addition,respectively.Shoot and root uptake of P,Mn,Cu,and Zn increased,but shoot Fe uptake decreased by 44.6%,with inoculation, when P was added.P addition reduced shoot P,Fe,Mn,Cu,and Zn uptake of AM plants,but increased root Fe and Mn uptake of the nonmycorrhizal ones.AM colonization therefore appeared to enhance plant tolerance to As in low P soil,and have some potential for the phytostabilization of As-contaminated soil,however,P application may introduce additional environmental risk by increasing soil As mobility.     

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.     

Potential of plant polyphenol oxidases in the decolorization and removal of textile and non-textile dyes

In this study an effort has been made to use plant polyphenol oxidases; potato （Solanum tuberosum） and brinjal （Solanum melongena）, for the treatment of various important dyes used in textile and other industries. The ammonium sulphate fractionated enzyme preparations were used to treat a number of dyes under various experimental conditions. Majority of the treated dyes were maximally decolorized at pH 3.0. Some of the dyes were quickly decolorized whereas others were marginally decolorized. The initial first hour was sufficient for the maximum decolorization of dyes. The rate of decolorization was quite slow on long treatment of dyes. Enhancement in the dye decolorization was noticed on increasing the concentration of enzymes. The complex mixtures of dyes were treated with both preparations of polyphenol oxidases in the buffers of varying pH values. Potato polyphenol oxidase was significantly more effective in decolorizing the dyes to higher extent as compared to the enzyme obtained from brinjal polyphenol oxidase. Decolorization of dyes and their mixtures, followed by the formation of an insoluble precipitate, which could be easily removed simply by centrifugation.     

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.     

Removal of heavy metals from sewage sludge by low costing chemical method and recycling in agriculture

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Organochlorine pesticides in soils under different land usage in the Taihu Lake region, China

A field study was conducted in the Taihu Lake region, China in 2004 to reveal the organochlorine pesticide concentrations in soils after the ban of these substances in the year 1983. Thirteen organochlorine pesticides (OCPs) were analyzed in soils from paddy field, tree land and fallow land. Total organochlorine pesticide residues were higher in agricultural soils than in uncultivated fallow land soils. Among all the pesticides, ΣDDX (DDD, DDE and DDT) had the highest concentration for all the soil samples, ranging from 3.10 ng/g to 166.55 ng/g with a mean value of 57.04 ng/g and followed by ΣHCH, ranging from 0.73 ng/g to 60.97 ng/g with a mean value of 24.06 ng/g. Dieldrin, endrin, HCB and α-endosulfan were also found in soils with less than 15 ng/g. Ratios of p,p'-(DDD DDE)/DDT in soils under three land usages were: paddy field ＞ tree land ＞ fallow land, indicating that land usage inlfuenced the degradation of DDT in soils. Ratios of p,p'-(DDD DDE)/DDT ＞1, showing aged residues of DDTs in soils of the Taihu Lake region. The results were discussed with data from a former study that showed very low actual concentrations of HCH and DDT in soils in the Taihu Lake region, but according to the chemical half-lives and their concentrations in soils in 1980s, the concentration of DDT in soils seemed to be underestimated. In any case our data show that the ban on the use of HCH and DDT resulted in a tremendous reduction of these pesticide residues in soils, but there are still high amounts of pesticide residues in soils, which need more remediation processes.     

Single and joint effects of pesticides and mercury on soil urease

The influence of two pesticides including chlorimuron-ethyl and furadan and mercury （Hg） on urease activity in 4 soils （meadow burozem and phaeozem） was investigated. The soils were exposed to various concentrations of the two pesticides and Hg individually and simultaneously. Results showed that there was a close relationship between urease activity and organic matter content in soil. Chlorimuron-ethyl and furadan could both activate urease in the 4 soils. The maximum increment of urease activity by chlorimuronethyl was up to 14%-18%. There was almost an equal increase （up to 13%-21%） in the urease activity by furadan. On the contrary, Hg markedly inhibited soil urease activity. A logarithmic equation was used to describe the relationship （P〈0.05） between the concentration of Hg and the activity of soil urease in the 4 tested soils. Semi-effect dose （ED50） values by the stress of Hg based on the inhibition of soil urease in the 4 soils were 88, 5.5, 24 and 20 mg/kg, respectively, according to the calculation of the corresponding equations. The interactive effect of chlorimuron-ethyl or furadan with metal Hg on soil urease was mainly synergic at the highest tested concentrations.