低温等离子体处理甲苯和二甲苯废气新技术通过专家鉴定

低温等离子体处理甲苯和二甲苯废气新技术日前通过专家鉴定。该课题针对污染严重而又难以治理的有机工艺废气采用了低温等离子体新技术,研制了样机并进行了中试,在浓度为万分之几,流速为10m/s,单级流量为500m3/h,电压为5400V时,苯的单级降解率为62％,甲苯为79.6％,     

低温等离子体在废气处理中应用探讨

现阶段,我国对异味恶臭污染处理方法的特点是:在设备运行中有较高的管理要求,运转需要较高的费用,需要较大的占地面积,也无法完全净化异味,产生二次污染的可能性比较大。低温等离子体是一项先进的消除恶臭和异味的技术,可以通过自由基和高能电子作用于污染物,污染物在短时间内可以分解,从而达到污染物降解的目的。笔者根据相关工作经验,主要探析低温等离子体在废气处理中应用的相关问题,供大家参考和借鉴。     

有机废气的等离子体协同光催化净化技术

低温等离子体光催化协同净化技术集成了低温等离子体和光催化的优势,两者相互协同,优势互补,是一种非常高效、节能的降解有机废气的方法。介绍等离子体光催化协同净化有机废气国内外研究进展,从作用机理、等离子体光谱、影响因素、协同等方面进行了阐述,并指出了今后研究的方向。     

广东某大型铜漆包线生产线有机废气治理工程

广东金雁电工有限公司是我国生产铜漆包线电缆的十大企业之一,该厂对漆包线生产过程中所产生的以苯、甲苯、二甲苯等苯系物为主的有机废气采用"低温催化燃烧+植物提取液高能雾化吸收"的处理工艺,在常规低温催化燃烧有机废气的基础上,运用植物提取液超微气态分散的原理,强化吸收净化废气并消除燃烧臭味。经过治理,苯、甲苯、二甲苯排放浓度均低于DB 44/27—2001《广东省地方标准大气污染排放限值》污染源二级排放标准限值,并消除了臭味的影响。该工艺具有运行可靠、去除效率高、成本低廉、管理方便等优点,值得在国内同类废气治理中推广应用。     

低温等离子体-催化协同净化有机废气研究进展

低温等离子体-催化协同净化技术是一种理想的环境污染治理技术,催化剂的加入可有效地提高废气治理的净化效果和二氧化碳的选择性,减少副产物的产生,并进一步降低能耗。分析了低温等离子体-催化协同净化有机废气的协同作用机理,阐述了反应器结构、催化剂参数、电参数以及工艺参数等对反应器性能的影响,并指出今后研究的发展方向。     

低温等离子体技术处理烟草臭气

在烟草生产过程中产生的废气是一种臭气污染.利用低温等离子体技术处理烟草废气,使排放气体达到<环境空气质量二级标准>(GB3095-1996),为进一步提高等离子体设备的处理效率提供了依据.实验中还考察了气体流量及设备功率变化对处理效率的影响,结果表明,处理系统中等离子体反应器体积不宜过大,在今后的应用中可以考虑针对不同的处理气量,采用反应器并联的形式;设备功率为6kw时,处理效率较高.     

低温等离子体技术处理烟草臭气

在烟草生产过程中产生的废气是一种臭气污染。利用低温等离子体技术处理烟草废气,使排放气体达到《环境空气质量二级标准》(GB3095-1996),为进一步提高等离子体设备的处理效率提供了依据。实验中还考察了气体流量及设备功率变化对处理效率的影响,结果表明,处理系统中等离子体反应器体积不宜过大,在今后的应用中可以考虑针对不同的处理气量,采用反应器并联的形式;设备功率为6kW时,处理效率较高。     

低温等离子体技术处理烟草臭气

在烟草生产过程中产生的废气是一种臭气污染。利用低温等离子体技术处理烟草废气,使排放气体达到《环境空气质量二级标准》(GB3095-1996),为进一步提高等离子体设备的处理效率提供了依据。实验中还考察了气体流量及设备功率变化对处理效率的影响,结果表明,处理系统中等离子体反应器体积不宜过大,在今后的应用中可以考虑针对不同的处理气量,采用反应器并联的形式;设备功率为6kW时,处理效率较高。     

生物滴滤法净化低浓度有机废气的实践研究

在工业快速发展之时,工业生产随之排放的废气也日益增加,其中废气污染物中所含的各种挥发性有机物(VOCS),严重污染空气,危害人体健康和生态环境。常规的处理方法为低温等离子与活性炭吸附处理,但是低温等离子净化设备使用时存在较大的安全风险,饱和后的活性炭的再生问题也较难解决,而生物滴滤法净化VOCS技术则是一种净化效率高,投资及运行成本低,符合安全和清洁生产原则的处理低浓度大风量VOCS气体的新型处理技术,具有广泛的工业应用前景。     

北京市典型城区餐饮业VOCs和PM2.5排放量估算

以北京市餐饮企业分布密度最大的西城区为案例区,通过对研究区域内餐饮企业进行实地污染物检测及排放活动水平调查,计算得到基于就餐人数、就餐时间、烹饪油用量和灶头数4种核算基准的餐饮业VOCs和PM_2.5排放因子,并利用排放因子法分别估算该区域在餐饮废气净化设备升级改造前后餐饮企业VOCs和PM_2.5年排放量.结果表明：本研究区域餐饮业废气净化设备升级改造前VOCs排放量范围为319.03~506.38t/a,改造后为92.14~109.89t/a;改造前PM_2.5排放量范围为166.55~211.09t/a,改造后为30.22~36.05t/a,排放量明显减少.餐饮业废气净化设备改造后VOCs和PM_2.5减排率分别为71%~82%和80%~86%,餐饮业废气净化设备升级改造减排效果良好.计算得到以街道为单元的餐饮源VOCs和PM_2.5排放强度范围分别为1.45~4.32t/km²和0.47~1.42t/km².通过PM_2.5实测浓度（小时值）数据分析,餐饮业废气净化设备升级改造前、后PM_2.5浓度平均减少了28.9%,最接近于用油量为核算基准的排放因子降低比例.     

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.     

Effects of chitosan on growth of an aquatic plant (Hydrilla verticillata) in polluted waters with different chemical oxygen demands

Effects of chitosan on a submersed plant, Hydrilla verticillata, were investigated. Results indicated that H. venicillata could prevent ultrastructure phytotoxicities and oxidativereaction from polluted water with high chemical oxygen demand (COD). Superoxide dismutase (SOD) activity and malondialdehyde (MDA) contents in H. verticillata treated with 0.1% chitosan in wastewater increased with high COD (980 mg/L) and decreased with low COD (63 mg/L), respectively. Ultrastructural analysis showed that the stroma and grana of chloroplast basically remained normal. However, plant cells from the control experiment (untreated with chitosan) were vacuolated and the cell interval increased. The relict of protoplast moved to the center, with cells tending to disjoint. Our findings indicate that wastewater with high COD concentration can cause a substantial damage to submersed plant, nevertheless, chitosan probably could alleviate the membrane lipid peroxidization and ultrastructure phytotoxicities, and protect plant cells from stress of high COD concentration polluted water.     

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

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