矿山酸性废水重金属沉淀分离研究

矿山酸性废水对环境的污染包括酸性废水和重金属离子两个方面,矿山酸性废水的治理也包括酸性废水和重金属离子处理两方面的内容。重金属沉淀分离是利用重金属离子的氢氧化物和硫化物沉淀溶度积不同,在控制不同的沉淀条件下,进行特定离子的沉淀分离,从而使得废水中的重金属离子得到处理,分步沉淀使得回收沉淀物保持较高的有价金属品位,更易于资源化。分步沉淀反应后,进行相应的固／液分离,并回流部分沉淀物至沉淀反应池,固／液分离后出水,经pH调节,可以达标排放或回用。     

放射性医疗废水的处理方法

目前可用于进行放射性同位素废水处理的方法很多,其中包括蒸发浓缩固化、活性炭吸附、离子树脂交换、化学混凝沉淀、生物吸附、貯留衰变及稀释排放等。在进行放射性医疗废水处理时,除了少量高浓度的药品分装残液需要用带有屏蔽的专门容器封装保存外,通常采用聍留衰变、离子树脂交换及稀释排放的方法进行处理。     

浅谈离子交换除盐再生废水的回收及利用

离子交换法制备除盐水过程中,再生离子交换树脂要排放大量的废水,文章提出了回收正洗废水作为再生水的方法,可节省除盐水和再生酸碱消耗,经济效益和环境效益可观。     

离子交换-膜法组合工艺处理镀镍废水的应用研究

镀镍漂洗废水水质单一,含有较高浓度的镍离子,具有较高的回收利用价值.本工程采用离子交换-超滤-反渗透组合工艺处理镀镍漂洗废水,利用离子交换系统浓缩回收废水中的镍离子,具有自动化程度高、回收利用有用金属、废水中水回用等特点.回收的Ni2+经进一步处理后可返回生产工序使用,处理后出水可回用到电镀生产漂洗工序中.镀镍漂洗废水中Ni2+质量浓度由424 mg/L降至1.0mg/L以下,CODcr由150 mg/L降至20 mg/L以下,SS由28 mg/L降至2mg/L以下.系统Ni2+的回收率能达到99％以上,废水回用率超过65％.     

应用离子交换处理镀铬废水

目前国内处理电镀含铬废水的方法,大致有以下几种:硫酸亚铁-石灰法;电解法;钡盐法;二氧化硫法;离子交换法等。 结合我厂情况,在1000升镀铬槽上采用离子交换技术进行了含铬废水的处理试验。我们采用复床二塔逆交换体外再生离子交换处理镀铬废水工艺,经过一年来的生产运转,实践证明,效果良好。我厂镀铬清洗废水,六价铬最高含量达350毫克/升,远远超过国家排放标准。经过净化后,废水可直接回用于镀铬零件清洗及树脂清洗水。树脂的再生液,可回收重铬酸钾、硫酸钠,用于镀锌钝化及镀镍上。含铬废水不再排放,既保护了环境,又节约了原料和大量用水。达到综     

含铅电镀废水闭路循环工艺的研究

实验研究表明采用离子交换－电解法工艺处理含铅电镀废水，出水达到低纯水标准，在电子工业中可回用于漂洗水。再生剂选用的有机酸，再生洗脱液电解后可回用作再生剂。电解过程中可回收重金属。     

综合一体化处理电镀废水技术及应用

针对电镀废水中含有多种重金属离子和氰化物,采用微电解、破氰预处理,再经中和混凝反应、沉淀、过滤等工艺进行处理,出水稳定达到国家污水综合排放标准(GB8978-1996)一级标准,可直接排放或回用作清洗水.     

废醪液用于酒精生产试验获通过

酒清废醪液回用于稀释糖蜜技术是目前废醪液代替清水用于水膜除尘技术的一个重要部分 ,省内目前有将废醪液中和回用或离心后回用的技术 ,而冷却沉淀直接使用尚未见成功报导。巧家糖厂在 2 0 0 0 /2 0 0 1榨季进行废水治理的同时 ,对废醪液用于酒精生产进行攻关 ,经数十次小试 ,采用废醪液稀释糖蜜后 ,成熟醪含酒率在 10～ 11% ,回用量约占废醪液总量的 2 0 % ,其他方面尚未发现不良影响。榨季结束后 ,巧家糖厂将组织有关工程技术人员对该技术实施工业化生产做准备 ,在 2 0 0 1/2 0 0 2榨季实施废醪液用于酒精生产试验获通过@杨隆才…     

化学沉淀—离子交换法处理低放射性废水

本文介绍 ORNL 国家实验室,受~(90)Sr 与~(137)Cs 放射性同位素轻度污染的废水采用过滤、强酸性阳离子交换树脂进行处理,存在着树脂再生及二次污染废水处理费用高等问题。为解决上述问题,经小型实验室试验,确定沉淀与离子交换的最佳组合方式。试验提供了四条工艺流程,其中三条进行了中试和工业性试验。本文概述试验结果,并列举典型试验数据,对工艺流程进行分析。     

羽绒水洗废水处理及回用技术

介绍了羽绒废水的水质特点及回用难点,采用水力澄清+A/O+过滤+消毒相结合的工艺处理水洗羽绒废水,考虑了对羽绒的回收,生物处理后的废水经过滤后回用于水洗羽绒工艺的前段,使之达到某些羽绒工艺用水的回用要求。     

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.