关于城市污水治理问题的研究

随着城市居民生活质量的提高,城市污水排放量逐渐增长,对污水的处理需求更大,但是当前城市污水处理系统不能满足逐渐增长的污水处理需要,这造成了城市生活污水乱排放现象,使城市环境和地下水资源遭到威胁。目前,城市污水处理系统虽然有所改进,但仍然不能满足需求,因此,要提高污水处理系统与技术水平,保证污水的处理更加有效,才能保护城市人民生活环境,加快城市发展步伐。本文主要研究了城市污水治理的问题。     

城市污水处理技术与工艺研究进展综述

随着城市的发展和人民生活水平的提高,城市污水排放量日益增大,且污水成分日趋复杂,迫切需要适应各地经济发展和环境保护目标的污水处理技术。本文重点介绍了城市污水生物处理技术之一活性污泥法中的4种污水处理工艺,同时介绍了曝气生物滤池污水处理方法,并对组合技术处理城市污水进行了展望。     

城市污水处理厂的环境影响及整改措施

随着我国社会经济的不断发展,我国的城市建设取得了举世瞩目的成就。城市发展迅速,而作为城市能够正常健康运转的基础设施之一的城市污水处理厂也渐渐受到了人们的关注,城市离不开水,有用水就会有废水污水,如何处理好城市污水成为城市难题,污水处理对环境的影响是难免的,重要的是如何更好的做好水处理工作,本文将结合城市污水处理中存在的一些对环境的影响问题进行探讨,希望能够对城市污水处理有所帮助。     

城市污水处理现状及其发展趋势分析

随着我国社会经济与科技快速发展,我国城市也得到飞速发展,而城市人口剧增,导致污水排放量不断加大,由于城市污水处理设施仍存在缺陷,故无法有效治理城市污水,不仅使得城市环境受到污染,还给城市居民的生活环境质量带来影响。为此,如何提高城市污水处理效率成为当前城市发展过程中重点研究内容。本文就城市污水现状及其发展趋势展开分析。     

城市污水厂污泥处理技术分析

随着工厂数量的不断增多,生活污水等成为现代城市污水厂污水的重要来源,强化对污水的治理是净化环境、提高水资源利用率的有效途径,以满足城市的现代化建设。现阶段,我国的城市污水厂污泥处理技术还不够纯熟,污泥处理效率不高,对污水处理工作构成严重的威胁,是当前城市污水厂处理的关键所在。本文就当前我国城市污水厂污泥处理技术进行分析与探究,并结合国外的先进技术对其进行了优化与完善。     

发展适合中国国情的城市污水处理技术

在我国，绝大部分江河湖泊都不同程度地受到了污染。这主要是与我国的经济发展状况及污水治理水平有关。我国目前工业废水治理率不足70％，达标率不到50％，年排放18900896t生活污水，其中80％未经处理直接排放。水体质量正逐步恶化，如果不采取行之有效的措施，有朝一日，恶化的水体将对人类的生存造成威胁。近年来我国对废水特别是城市污水处理高度重视，国家甚至把城市污水厂建设作为拉动国民经济增长的重要手段。九五期间开工建设的城市污水厂近200个，总投资数百亿元，这表明了我国治理污水、改善环境的决心很大。目前我国城市污水处理…     

试分析城市生活污水资源化利用

本文首先介绍了城市生活污水资源化利用的重要意义,然后对城市生活污水资源化利用进行了可行性分析,接着解析了城市污水资源化利用的影响因素,并结合笔者多年相关工作经验,提出了完善污水处理配套设置、建立并完善相关政策和法规体系、设立合理水价体系等实现城市污水资源化利用的有效措施。希望能为探究城市生活污水资源化利用提供一定理论支撑。     

城市综合污水资源化可行性分析

最近１０多年来，我国城市污水的排放量越来越大，靠近城市河段的水质明显下降，成为我国非常突出的环境问题之一。另一方面，随着城市综合经济实力的增强和居民生活水平的提高，消除污水对社会、经济和环境负面影响，也成为提高城市环境舒适性的一项重要内容。目前，常规方法治理污水所需资金庞大，对地方财政来说是一个不堪重负的包袱。山东省寿光市根据当地有大量无法直接用于农业生产而被遗弃的荒碱地的条件，采用以芦苇湿地为主体的污水处理工艺，达到了城市综合污水达标排放的目的。该市利用经过处理达到排放标准的污水用于压盐碱，将…     

城市污水处理及回收再利用技术

随着城市化和经济建设的快速发展,城市污水排放量迅速增加,大量未经处理的生活污水任意排放,将会给城市水环境造成严重的污染,影响生活环境质量和城市的可持续发展。本文从污水处理技术的物理处理法、生物处理法和化学处理法几个分类上简要介绍了城市污水处理技术的发展现状,各技术指标和应用,并指出城市污水处理及回收再利用技术的发展趋势。     

城市污水处理过程中恶臭气体释放的研究进展

长期以来,我国城市污水处理相关工作人员职业病频发,与城市污水处理过程中会释放出大量的有毒有害气体有重要关系,我国现有的《城镇污水处理厂污染物排放标准》对水质排放指标作了明确规定,但对于污水处理过程中释放的气体污染物的类型及排放限值缺少详细说明.本文对城市污水处理厂不同污水处理工艺及不同污水处理单元在运行中所释放的气体污染物的特征进行了归纳总结,阐述了城市污水处理厂释放的主要恶臭挥发性有机物的产生途径、释放量及影响因素,并指出目前城市污水处理厂释放的气体污染物主要通过尾气末端收集综合处理的方式进行治理,而对于工艺运行参数与气体污染物释放特征之间的相关性关系仍需深入研究.     

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.     

Degradation of metabolites accumulated of benzo[a]pyrene by coupling Penicillium Chrysogenum with KMnO4

Several main metabolites of benzo[a]pyrene （BaP） formed by Penicillium chrysogenum, Benzo[a]pyrene-1,6-quinone （BP 1,6- quinone）, trans-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene （BP 7,8-diol）, 3-hydroxybenzo[a]pyrene （3-OHBP）, were identified by high-performance liquid chromatography （HPLC）. The three metabolites were liable to be accumulated and were hardly further metabolized because of their toxicity to microorganisms. However, their further degradation was essential for the complete degradation of BaP. To enhance their degradation, two methods, degradation by coupling Penicillium chrysogenum with KMnO4 and degradation only by Penicillium chrysogenum, were compared; Meanwhile, the parameters of degradation in the superior method were optimized. The results showed that （1） the method of coupling Penicillium chrysogenum with KMnO4 was better and was the first method to be used in the degradation of BaP and its metabolites; （2） the metabolite, BP 1,6-quinone was the most liable to be accumulated in pure cultures; （3） the effect of degradation was the best when the concentration of KMnO4 in the cultures was 0.01% （w/v）, concentration of the three compounds was 5 mg/L and pH was 6.2. Based on the experimental results, a novel concept with regard to the bioremediation of BaP-contaminated environment was discussed, considering the influence on environmental toxicity of the accumulated metabolites.     

Impact of atrazine and nitrogen fertilizers on the sorption of chlorotoluron in soil and model sorbents

Sorption of chlorotoluron in ammonium sulfate, urea and atrazine multi-solutes system was investigated by batch experiments. The results showed application of nitrogen fertilizers to the soil could affect the behavior of chlorotoluron. At the same concentration of N, sorption of chlorotoluron decreased as the concentration of atrazine increased on the day 0 and 6 in soil, respectively. The sorption of chlorotoluron increased from 0 to 6 d when soils were preincubated with deionized water, ammonium sulfate and urea solution for 6 d. That indicated incubation time was one of the most important factors for the sorption of chlorotoluron in nitrogen fertilizers treatments. The individual sorption isotherms of chlorotoluron in rubbery polymer and silica were strictly linear in single solute system, but there were competition sorption between pesticides or between pesticides and nitrogen fertilizers. That indicated the sorption taken place by concurrent solid-phase dissolution mechanism and sorption on the interface of water-organic matter or water-mineral matter.     

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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