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。     

愉悦度在恶臭污染感官评价中的应用

为完善我国恶臭污染感官评价指标,针对橡胶制品企业、面包房、垃圾填埋场3种典型气味源,采用9级愉悦度度量法测定不同气味源臭气浓度下的愉悦度,解析不同源臭气浓度、臭气指数和愉悦度间的关系,提出了臭气浓度和愉悦度综合评价理论模型,即气味源的干扰潜力=臭气指数×愉悦度。结果表明,橡胶制品企业和垃圾填埋场愉悦度为负值,面包房为正值。3种气味源臭气浓度与愉悦度的关系均符合二次多项式模型,相关系数均达到0.99以上。干扰潜力计算结果:橡胶制品企业为-200.91;垃圾填埋场为-144.80;面包房为79.66。通过对具有相似臭气浓度但来自不同气味源的样品进行干扰潜力的计算,能更直观地区分不同气味源的影响,从而准确识别重点排放源及关键排放单元。研究显示,愉悦度更能反映恶臭对人的心理影响及危害程度,将愉悦度应用到恶臭污染感官评价中十分必要。     

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.     

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。     

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.      

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.     

化学氧化法去除生活垃圾恶臭气体的效果研究

在逆流化学洗涤塔中分别采用芬顿、Na Cl O、H₂O₂溶液3种氧化剂作为洗涤液,对生活垃圾恶臭气体进行处理,测量处理前后气体的臭气(无量纲)、氨气和硫化氢浓度。实验表明,采用芬顿、Na Cl O、H₂O₂作为洗涤液的3组实验,臭气浓度去除效率分别为57.5%、56.3%、45.2%,氨气去除效率分别为69.4%、61.5%、69.7%,硫化氢去除效率分别为20.0%、37.5%、13.3%。综合考虑成本和操作性,使用Na Cl O处理生活垃圾恶臭气体最切实可行。     

餐厨垃圾生化处理机工艺恶臭污染特征研究

以上海某基于餐厨垃圾生化处理机工艺的企业为研究对象,通过筛选餐厨垃圾关键测试物质,测试案例企业各处理工艺有组织排放口、厂区及厂界无组织排放中的挥发性有机物（VOCs）及恶臭物质情况,结合异味活度（OAV）指标评价识别典型恶臭物质,深入分析餐厨垃圾好氧生化处理机企业的恶臭污染特征及关键影响因素。结果表明：VOCs及恶臭物质浓度表现为预处理车间>生化车间>深加工车间,排放成分主要为醇类、羰基类、硫化物和芳香烃等有机物;主要的恶臭物质为乙硫醇、丁硫醇、甲硫醇和乙硫醚等硫化物;废水处理设施是案例企业恶臭产生的潜在主要来源之一,包括废水厌氧罐的沼气泄漏、废水处理设施的无组织臭气逸散等;餐厨垃圾好氧生化处理类型企业对周边的恶臭污染与其生产工序具有显著关系。建议同类型企业可通过减少无组织臭气排放环节、建立沼气泄漏定期检测与应急管理制度、提高末端装置运行效果等方面缓解恶臭污染问题。

     

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.     

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

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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.     

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.