厨余垃圾堆肥过程中恶臭物质分析

恶臭污染已成为生活垃圾堆肥过程中的主要环境问题.以大类粗分后的厨余垃圾作为研究对象,利用嗅觉测定法和GC-MS分析了不同阶段堆肥尾气的臭气浓度和恶臭化合物的种类及其排放浓度,并对不同堆肥阶段臭气浓度和恶臭物质排放浓度的相关性进行分析.结果表明,厨余垃圾堆肥过程中共检测到43种挥发性有机物,其中含硫臭气物质5种,烃类化合物22种,芳香烃类化合物11种,其它物质5种.通过相关性分析,发现硫化氢、甲硫醇、1,3-二甲基苯和邻二甲苯与臭气浓度极显著相关(P<0.01),二甲二硫和对二甲苯与臭气浓度显著相关(P<0.05),因此在厨余垃圾堆肥过程中要对这6种臭气物质进行重点监测和控制.     

垃圾填埋场臭气评价方法研究

本论文通过对生活垃圾填埋场填埋气体臭气物质组分及其含量的分析,依据现行的国家恶臭污染物的居住区、工作场所和场界浓度的标准限值,根据臭气浓度和强度的关系式,转化为该气体臭气强度,并给出环境影响评价标准值。最后以黔西县城生活垃圾卫生填埋处理工程为实例,验证该标准的实用性。将该标准值应用于恶臭污染物的环境影响评价,能科学、直观地反应出恶臭污染物对大气环境的影响。采用臭气强度标准对恶臭污染物进行评价是一种针对性、可操作性、比较实用的评价方法,该方法为产生恶臭物质项目的臭气评价提供了借鉴。     

深度脱水印染污泥滚筒干化特性中试

采用燃油烟气模拟热电厂烟气,实验研究了深度脱水印染污泥的滚筒干化特性,分析了滚筒转速、烟气流速及滚筒长度对污泥干化效果、干燥效率的影响规律,同时也探讨了进口温度对干化尾气污染物排放特性的影响。结果表明:滚筒转速对深度脱水印染污泥在滚筒中的停留时间有重要影响,同时也是影响出口污泥含水率的最主要因素,而烟气流速则是影响干燥效率的最主要因素。对于深度脱水印染污泥,滚筒干燥容积传热系数为0.361~1.168 k J/(m3·s·℃),烟气流速会对其有一定的影响,而滚筒转速对其的影响很小。干化尾气中除NH3和臭气浓度高于恶臭污染物厂界3级标准值外,其他各污染物的排放浓度均低于国家排放标准。为抑制污泥中NH3、H2S及苯系物的释放,深度脱水印染污泥滚筒干化的烟气温度应控制在190℃以内。     

污泥直接干化尾气中恶臭污染物质重要性评价:以指标权重评分法为例

利用水泥窑协同处置污泥可同时实现污泥的无害化、减量化和资源化.水泥回转窑处置污泥时须先对污泥进行干化使其含水率达到要求.污泥受热干化时会释放恶臭物质,易引发恶臭污染,对周围环境和居民生活造成影响.以污泥直接干化产生的尾气为对象,基于目前国内外恶臭污染相关规定,综合考虑污泥直接干化产生的尾气中物质浓度、嗅阈值、阈限值、气味安全级别以及饱和蒸气压,通过指标权重评分方法筛选出污泥直接干化产生尾气中的主要恶臭污染物.以恶臭污染潜力为评价目标,风险指标和臭气排放强度为评价指标,通过韦伯-费希纳定律构建污泥直接干化产生尾气的恶臭污染潜力分级评价模型,形成适合污泥直接干化产生尾气的恶臭污染潜力分级评价方法.     

基于恶臭气体扩散数值模拟的垃圾中转站选址

城市垃圾中转站恶臭气体扩散问题是居民非常关注的焦点。采用计算流体力学方法对某拟建垃圾中转站和周围建筑物附近的流场和可能泄漏的恶臭气体的扩散进行了数值模拟,分析了不同风速和风向对流场结构和恶臭气体扩散特性的影响规律。结果表明:在相同风向不同风速下,无因次化流场结构基本相同;风速高时恶臭气体迅速扩散,不影响周围建筑物;接近静风时,恶臭气体能够扩散至垃圾中转站的连体建筑和南侧学生宿舍,但浓度已降低约3个数量级;风速接近静风的东风和南风条件下,恶臭气体扩散快,影响区域有限。总体上,该拟建垃圾中转站的选址合理。该研究过程可为类似项目选址的合理性评判提供科学参考。     

有机垃圾处理机排放臭气的生物脱臭研究

文章利用生物滴滤塔对有机垃圾处理机排放的恶臭气体进行了脱臭研究。考察了生物滴滤塔的启动情况:装置启动7d后,NH_3排放浓度达到城市恶臭气体排放标准,11d后,H_2S排放浓度达到标准;在此基础上,研究了气体表面负荷、喷淋密度和pH值对净化效率的影响,发现实验条件下的适宜参数是:气体表面负荷≤300m~3/m~2·h,喷淋密度为0.1～0.2m~3/m~2·h,pH值维持在6.0～7.0。研究结果对于有机垃圾生物处理排放恶臭气体的净化具有一定的应用价值。     

典型生活垃圾处理设施恶臭排放特征及污染评价

为研究生活垃圾处理设施恶臭污染排放特征,分别在北京市生活垃圾填埋、焚烧、堆肥3种工艺的前处理车间采集恶臭样品,利用冷阱富集-气质联用(GC/MS)技术对恶臭气体进行分析.结果表明,检测到的恶臭物质主要分为6大类:芳香烃化合物、硫化物、卤代物、烯烃、烷烃和含氧有机物.其中,填埋工艺的前处理车间共检测出50种物质,质量浓度为100.069mg·m~(-3),理论臭气浓度OU_T为350.611,综合臭气指数N为25.448.焚烧工艺的前处理车间共检测出55种物质,质量浓度为36.052 mg·m~(-3),理论臭气浓度OU_T为141.434,综合臭气指数N为21.506.堆肥工艺的前处理车间共检测出34种物质,质量浓度为25.382 mg·m~(-3),理论臭气浓度OU_T为27.547,综合臭气指数N为14.401.利用阈稀释倍数的恶臭贡献值计算方法,初步识别填埋工艺的前处理车间特征恶臭污染物质为:二甲二硫醚、乙酸丁酯、对二乙苯和乙醇;焚烧工艺的前处理车间特征恶臭污染物质为:甲硫醇、二甲二硫醚、乙醇和柠檬烯;堆肥工艺的前处理车间特征恶臭污染物质为:乙醇、二甲二硫醚、乙酸丁酯和柠檬烯.     

生活垃圾初期降解过程中污染物释放及恶臭污染研究

生活垃圾初期降解主要发生在生活垃圾产生到被妥善处置之前,初期降解过程中伴随产生的气态和液态污染物可直接进入环境,影响居民生活环境. 为了明确生活垃圾初期降解过程中的污染情况,结合我国生活垃圾基本组成开展实验室模拟试验,分析生活垃圾初期降解过程中不同途径产生的污染物的释放特征及其恶臭污染的影响. 结果表明:生活垃圾中约20%的氮元素和硫元素在初期降解过程以气体或渗滤液的形式释放到环境中. 其中,CO₂是生活垃圾初期降解过程中最主要的气态污染物,约占总累积产气量的43%;挥发性有机物(volatile organic compounds, VOCs)产生量较少,但种类复杂,其中乙醇的体积分数最大,约占VOCs总体积分数的85%. 渗滤液产生率较低(约30.94 mL/kg,以湿垃圾计),但其中化学需氧量、氨氮和硫酸盐的浓度远超GB 8978—1996《污水排放综合标准》限值. 生活垃圾初期降解过程中理论臭气浓度达205.14,甲硫醚和乙醇是重要的典型恶臭物质. 研究显示,生活垃圾初期降解过程产生的气态污染物主要包括CO₂和VOCs,渗滤液中污染物浓度远超相关污染排放限值,由VOCs导致的恶臭污染达到3级臭气强度. 因此,为了降低生活垃圾初期降解过程中的环境污染,建议缩短生活垃圾清运的时间,并重点关注乙醇和甲硫醚等恶臭物质.      

臭气强度在恶臭污染物环境空气影响中的应用研究

以兰州某石化公司化工污水处理厂恶臭治理项目为例,在确定恶臭气体的污染源源强的基础上,采用AERMOD模式预测污染物扩散情况。结果表明,添置除臭装置后,NH3的臭气浓度减少了90%,VOCs的臭气浓度减少了88%。同时,当恶臭污染物浓度达到环境质量浓度标准时,NH3的臭气强度为1．40级,VOCs的臭气强度为0．82级,人们仍能感觉到气味。因此石化企业在进行恶臭治理过程中需综合考虑污染物的环境空气质量浓度标准和臭气强度,以期改善环境空气质量。     

天津市环境空气中恶臭感官定量评价分析

为研究环境空气恶臭污染特征,以天津市区为研究区域,分别在夏秋两季对天津市内六区的环境空气中恶臭感官浓度进行了监测。结果显示,在观测期间臭气浓度在限值（以《恶臭污染物排放标准》厂界臭气浓度限值20作为参照）范围以内的样品数量夏季占63％,而秋季占18％;通过多元线性回归方法建立了典型恶臭污染物与恶臭感官浓度的定量表达式,计算出典型恶臭污染物对市区环境空气的臭气浓度贡献率占59％。通过对实测值与预测值的拟合情况的分析,表明该回归方程可以较好的预测天津市环境空气中夏季恶臭感官浓度。     

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.     

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.     

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.     

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.     

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.     

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.     

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.     

基于综合水质标识指数和对应分析法的校园河道水质评价

以三峡大学的校园河道求索溪为研究对象,利用综合水质标识指数法确定求索溪水质类别,分析其水质时空变化规律,并利用对应分析法得出求索溪中不同监测点的主要污染因子.研究结果表明:求索溪整体的综合水质标识指数为7.423,整体水质为劣V类(地表水环境质量标准GB 3838-2002)且黑臭.从时间变化来看,求索溪4月份的水质最差,5月份次之,4、5月份所有监测点的水质都劣于V类且黑臭;8月份水质最好,水质为Ⅳ类;从空间分布来看,8个监测点综合水质标识指数均超过6.0,水质为劣V类,其中6号监测点的水质相对最好,监测点3号的水质相对最差;对应分析法得出求索溪的整体水体污染程度受总氮因子的影响最大,其次为总磷.该研究拟为求索溪及类似校园河道的水环境治理研究提供基础依据和参考.     

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.