渗滤液回灌对填埋垃圾含水率的影响研究

文章通过模拟实验研究了不同的渗滤液回灌频率、回灌量和回灌速率对压实密度不同的垃圾的含水率的影响。研究表明,由于通道流的存在和影响,渗滤液的产生时间提前于填埋垃圾达到其有效贮水率的时间;渗滤液回灌频率越高、回灌量越大、回灌速率越慢、垃圾体温度越低、垃圾压实密度越高,则填埋垃圾的有效贮水率越大、含水率越高。在实施渗滤液回灌操作时,须综合考虑滤液回灌频率、回灌量、回灌速率、垃圾温度和垃圾压实密度等影响因素。     

填埋场垃圾堆体平面压实工程试验研究

原生垃圾密度很小，为提高填埋垃圾堆体密实度、延长填埋场使用寿命，对填埋垃圾进行压实处理很重要。本文通过现场工程试验对影咱填埋垃圾堆体平面压实效果的主要因素进行了系统研究。实验结果表明：为取得最佳的垃圾堆体平面压实效果，最佳垃圾摊铺厚度在0.5m—0.7m之间，最佳机械行程次数为3次，增加碾压次数有利于提高垃圾堆体密实度，垃圾最佳含水率在30％——50％之间。     

填埋垃圾渗透系数的研究进展

填埋是我国城市生活垃圾的主要处理方式,我国南方填埋场普遍面临的一个问题是渗滤液水位较高。垃圾渗透系数不仅在控制渗滤液水位技术方面有重要作用,且影响填埋气的排出及回收利用率。总结了垃圾渗透系数影响因素和调节方法方面的研究,得出影响因素包括垃圾密度、垃圾组分、降解程度、压实程度等,调节方法则有改变影响因素和加入惰性材料两种。在此基础上对填埋场控制渗滤液水位的工程技术手段和提高填埋体回收利用率的途径提出了新建议。     

填埋场垃圾堆体斜面压实工程试验研究

通过现场工程试验对填埋垃圾堆体斜面压实效果进行了影响因素的研究．试验证明：在垃圾填埋作业过程中，压实机械对填埋垃圾堆体斜面压实的效果受垃圾堆体斜面坡度、垃圾堆体构造层厚度、压实机械行程次数以及压实机械的行驶方向等因素影响显著．实验结果表明：为取得最佳的垃圾堆体斜面压实效果，斜面最佳坡度在1：5～1：4之间，最佳垃圾摊铺厚度在0．6m～0．7m之间，最佳机械行程次数为3次，压实机械的行驶方向为坡下向坡上．     

主压缩沉降阶段垃圾填埋体渗透特性研究

针对垃圾填埋体的研究主要集中在降解及垃圾渗滤液处理,而其渗透特性研究不足的现状,选取处于4种压力状况下的垃圾填埋体,对其主压缩沉降阶段渗透特性进行室内物理试验,结合试验数据对垃圾填埋体渗透性能变化规律进行分析研究.结果表明,4种压力状况下垃圾填埋体试验测定分析符合达西定律,其COD变化处于产酸阶段,对渗透性能的影响可以不予考虑;在此基础上,对垃圾渗透系数计算表明,处于主压缩沉降阶段内,除没有施加压力状况下垃圾填埋体渗透性能变化规律与其他试验表现不尽相同外,其他垃圾填埋体渗透系数变化大致符合自然指数规律,而4种压力状态下的垃圾填埋体渗透系数数值均在10~(-4.5)～10~(-5.3) m·s~(-1)的范围内,与典型垃圾渗透系数的代表值相一致.     

长春市简易垃圾填埋场中垃圾特性研究

从长春市一个封场垃圾填埋场中系统采集了不同填埋年龄(8~12年和25~30年)和不同位置(上层和下层)的垃圾样品,并对其基本特性进行了分析。结果发现,填埋垃圾总体呈弱碱性,含水率随填埋时间的增加而减小,上层垃圾含水率低于下层垃圾;从垃圾组成、有机质和生物可降解物(BDM)来看,8~12年的填埋垃圾仍处于不稳定状态,而25~30年的垃圾基本达到稳定化,但上层和下层垃圾的降解程度无明显区别。这表明传统填埋场中垃圾稳定化至少需要几十年的时间。因此开发能够加速垃圾稳定性填埋场的生物反应器修复技术具有重要意义,填埋垃圾的特性分析则为工程设计提供了必要的基础数据。     

生活垃圾非饱和渗透性质测定的多步出流方法

传统土壤渗透性测量方法直接测量填埋生活垃圾的渗透性质误差较大.本实验现场测定六里屯填埋场原状垃圾土饱和含水率和饱和渗透系数,其平均含水率随填埋深度增加而增大,平均渗透系数为0.018 5mm·s^-1.在保证容重相同条件下,用多步出流法实验室测定扰动样品水分特征曲线和非饱和渗透系数.运用渗压出流和理论拟合测试技术,为建立渗透参数的随机分布模型提供参数测定方法.实验结果与模型显著相关.通过实验及模型模拟,揭示了填埋垃圾水分特征曲线的变化规律,证明多步出流法是适用于填埋场非饱和渗透性质测定的有效方法.     

北京市某垃圾卫生填埋场堆山及覆盖工程实例

填埋场堆山及覆盖工程是指垃圾从地面向上填埋作业,至设计标高或填埋场停止使用高度的过程。为避免堆体沉降过大对堆体的稳定造成影响,根据勘察报告对垃圾填埋区进行的沉降分析,利用陈腐垃圾对沉降最大区域进行压实、垫高,保证垃圾堆体压实密度大于0.9;为减少渗沥液的产生保证渗沥液、沼气收集及导排系统安全有效的运行,采用基础构建的方式减少填埋作业面,从而减少雨季雨水的渗入;待堆体形成后,通过在堆体顶部及边坡铺设防渗及导排层对渗沥液和沼气进行疏导和收集,降低渗沥液和沼气对堆体稳定以及周边环境造成的影响,并铺设生态恢复层,美化环境。     

上海老港生活垃圾填埋场陈垃圾的基本特性研究

对上海老港生活垃圾填埋场6年填埋龄和10年填埋龄陈垃圾的基本特征进行了测试研究，这些特性包括粒径分布，臭味、微生物数量、含水率、总磷、总氮、饱和水力渗透系数等。研究结果：上海老港生活垃圾填埋场中6年以上填埋龄陈垃圾已可以开采用使用；对其多种用途的开发主要限于陈垃圾中粒径小于15mm的细料部分；此细料是极为优良的污染物生物处理基质。     

生活垃圾填埋过程含水率变化研究

为分析垃圾在好氧和厌氧条件下降解过程中含水率变化的规律,采用时域反射测量(time domain reflectometry,TDR)技术监测了垃圾填埋过程中含水率的变化情况.结果表明,填埋过程中垃圾体积含水率随时间逐渐增大,垃圾持水性能不断提高.好氧初期垃圾内水量变化与含水率变化正相关,好氧后期则为负相关;厌氧填埋过程中,垃圾沉降压缩是含水率变化的主要原因.垃圾TDR读数与基于物质衡算的垃圾体积含水率计算值之间有较好的相关性,好氧填埋过程两者最大偏差约为±5%,厌氧填埋过程两者最大偏差约为±2%,TDR技术适用于实际填埋工程的含水率测量.     

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.     

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.     

Effects of two sludge application on fractionation and phytotoxicity of zinc and copper in the soil

The potential harm of heavy metals is a primary concern in application of sludge to the agricultural land. A pot experiment was conducted to evaluate the effect of two sludges on fractionation of Zn and Cu in soil and their phytotoxicity to pakchoi. The loamy soil was mixed with 0%, 20%, 40%, 60% and 80% (by weight) of digested sewage sludge (SS) and composted sludge (SC). The additions of both sludges caused a significant raise in all fractions, resulting in that exchangeable (EXCH) and organic bound (OM) became predominance of Zn and organic bound Cu occupied the largest portion. There was more available amount of Zn and Cu in SS treatments than SC treatments. During the pot experiment, the concentration of Zn in EXCH, carbonate (CAR) and OM and Cu in EXCH and OM fractions decreased in all treatments, so their bioavailability reduced. Germination rate and plant biomass decreased when the addition rate was high and the best yield appeared in 20% mixtures at the harvest of pakchoi. The two sludges increased tissue contents of Zn and Cu especially in the SS treatments. Zn in pakchoi was not only in relationship to ΔEXCH and ΔCAR forms but also in ΔOM forms in the sludge-soil mixtures. Tissue content of Cu in pakchoi grown on SC-soils could not be predicted by ΔEXCH. These correlation rates between Zn and Cu accumulation in pakchoi and variation of different fractions increased with time, which might indicate that sludges represented stronger impacts on the plant in long-term land application.     

Intraspecific differences in effects of co-contamination of cadmium and

A hydroponic experiment was carried out to study intraspecific differences in the effects of different concentrations of cadmium (Cd)(0-10 mg/L) and arsenate (As(V)) (0-8 mg/L) on the growth parameters and accumulation of Cd and As in six wheat varieties Jing-9428, Duokang-1, Jingdong-11, Jing-411, Jingdong-8 and Zhongmai-8. The endpoints of wheat seedlings, including seed germination,biomass, root length and shoot height, decreased with increasing the Cd and As concentrations. Significant differences in seed germination, biomass, root length, shoot height and the accumulation of Cd and As were observed between the treatments and among the varieties (p ＜ 0.05). The lethal dosage 50% were about 20, 80, 60, 60, 80 and 20 mg As/L for Jing-9428, Duokang-1, Jingdong-11,Jing-411, Jingdong-8 and Zhongmai-8, respectively, and the corresponding values for Cd were about 30, 80, 20, 40, 60 and 10 mg Cd/L, respectively. Among the six varieties, Duokang-1 was found to be the most resistant to Cd and As toxicity, and Zhongmai-8 was the most sensitive to Cd and As co-contamination. The resistance of the six varieties was found dependant on the seedling uptake of Cd and As. Duokang-1 was the most suitable for cultivation in Cd and As co-contaminated soils.     

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

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Isolation and preliminary characterization of a 3-chlorobenzoate degrading bacteria

A study was conducted to compare the diversity of 2-, 3-, and 4-chlorobenzoate degraders in two pristine soils and one contaminated sewage sludge. These samples contained strikingly different populations of mono-chlorobenzoate degraders. Although fewer cultures were isolated in the uncontaminated soils than contaminated one, the ability of microbial populations to mineralize chlorobenzoate was widespread. The 3- and 4-chlorobenzoate degraders were more diverse than the 2-chlorobenzoate degraders. One of the strains isolated from the sewage sludge was obtained. Based on its phenotype, chemotaxonomic properties and 16S rRNA gene, the organism S-7 was classified as Rhodococcus erythropolis. The strain can grow at temperature from 4 to 37℃. It can utilize several （halo）aromatic compounds. Moreover, strain S-7 can grow and use 3-chlorobenzoate as sole carbon source in a temperatures range of 10-30℃ with stoichiometric release of chloride ions. The psychrotolerant ability was significant for bioremediation in low temperature regions. Catechol and chlorocatechol 1,2-dioxygenase activities were present in cell free extracts of the strain, but no （chloro）catechol 2,3- dioxygenase activities was detected. Spectral conversion assays with extracts from R. erythropolis S-7 showed accumulation of a compound with a similar UV spectrum as chloro-cis,cis-muconate from 3-chlorobenzoate. On the basis of these results, we proposed that S-7 degraded 3-chlorobenzoate through the modified ortho-cleave pathway.     

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.