动电技术去除城市污泥中重金属的研究概况

介绍了动电技术去除重金属的基本原理和常见的几种动电技术工艺,并总结了动电技术处理城市污泥中重金属的应用研究概况。     

城市污泥中有害重金属检测与评估

城市污泥是活性污泥法处理城市生活污水和工业污水产生的固体废弃物,污水中50%～80%以上的重金属浓缩在产出的污泥中.Hg、Cd、Pb、Cr（Ⅵ）等重金属是我国第一批立法颁布的重点控制污染物,能在人体内长期积蓄并产生毒害.污泥中重金属的存在严重危害着包括人类在内的各种生命体的健康与生存,而且成为限制其资源化的主要障碍因素.本文从沈阳的污染状况出发,采用电感耦合等离子体质谱技术,对沈阳污水处理厂污泥中主要污染的重金属元素进行分析,以期为沈阳的环境质量评价和污染监控提供参考依据.     

城市污泥中重金属的去除方法研究进展

简述了全国范围内污泥中重金属赋存水平以及污泥施用到农田后重金属产生的危害,重点阐述了采用物理、化学、微生物方法去除污泥中重金属,并对这几种方法的去除效率、处理成本以及环境安全性进行了比较,最后展望了今后进一步研究的发展方向和工作重点。     

不同钝化剂对污泥堆肥过程中重金属形态的影响研究

利用污泥和秸秆进行高温堆肥,研究粉煤灰、磷矿粉、沸石和草炭4种钝化剂对污泥堆肥中重金属（Cu、Zn、Pb、Cr）形态的影响。结果表明：堆肥过程中添加钝化剂可有效降低污泥中重金属有效态的含量,其中以粉煤灰的钝化效果最为显著。粉煤灰用于污泥堆肥不仅实现污泥的资源化,而且解决了粉煤灰的利用问题。     

施用城市污泥对土壤中重金属积累和迁移的影响

目的 了解城市污泥农用后土壤重金属的积累和迁移。方法 于1998年分不同季节，从苏州、无锡、常州3个城市污水处理厂采集污泥样本，用原子吸收光谱仪分析样本中重金属(Pb、Zn、Cu、Cd、Hg、As)含量和不同形态含量，分析污泥农用后土壤重金属积累及迁移特性。结果 城市污泥重金属含量远高于土壤背景值，3城市污泥中Zn含量均超标，分别达到1199，00、784．00、1216．00mg／kg。长期施用能导致土壤重金属积累。污泥中重金属具有一定的活性和潜在迁移性。结论 城市污泥农用可能会导致土壤和生物体重金属积累，存在着一定的环境重金属积累风险。     

不同固体浓度下不同菌去除重金属效果

在污泥中分别接种10％的氧化硫硫杆菌菌液与氧化亚铁硫杆菌菌液，研究了不同菌种情况下，10g／L到40g／L梯度的污泥浓度对生物淋滤重金属Zn和Cu的影响。实验表明，在不同固体浓度下两种菌对污泥中Zn和Cu的去除率都很高，污泥浓度越低，污泥中重金属的去除率越高。淋滤过程中，低固体浓度污泥，氮、磷、钾及有机质等营养物质流失量比高固体浓度污泥明显增多；而同浓度下，氧化硫硫杆菌在去除污泥中重金属的同时，营养物质的损失小于氧化亚铁硫杆菌。     

酸化污泥中重金属在电动力作用下的去除率研究

分析了长沙市某污水处理厂污泥中重金属分布.对污泥样品用HNO3进行酸化处理,酸化后pH值为3.2、1.9.分析了酸化处理后Cd、Zn、Cu在污泥中的形态分布.重点研究了酸化污泥中的Cd、Zn、Cu在电动力作用下的去除率.酸化污泥在电动力的作用下,经过5 d后,Cd、Zn的去除率明显提高,Cu的去除率提高相对较少.针对我国污泥中Zn含量较高的特点,提出在污泥厌氧消化处理时,同时用电动力处理污泥中的重金属,可大大提高重金属的去除率.     

城市污泥堆肥土地修复利用研究进展

综述了城市污泥堆肥在园林绿地、农田土壤、土地修复等领域的应用现状，分析了土地利用中存在的土壤重金属积累、臭气污染、养分含量低、肥效慢等主要问题，探讨了相应的对策。     

城市污泥重金属监测控制

分析了城市污泥的污染特性和其对生态环境的影响与危害。利用扫描电镜，x荧光分析仪，原子吸收光谱等现代分析技术对上海某城市污水处理厂污泥中复杂的化合物的形貌及无机化合物的物种进行了综合分析，确定了痕量重金属的存在状态，为控制、处理和资源化污泥提供理论依据。     

重金属污染土壤生物修复技术研究现状

土壤是生态环境的重要组成部分,与人类的生存和健康密切相关。目前,生物修复技术已开始成为土壤污染修复的主要处理技术。该文系统介绍了重金属污染土壤生物修复的概念、生物修复特点及其机制、类型,重点论述了植物、微生物、动物对重金属污染土壤的修复技术方面的研究进展,并在此基础上提出了一些见解和看法,为今后该方面的研究提供参考。     

固化污泥制作回填土及营养土的研究

采用镁系固化剂 (MI 固化剂) 对污泥进行固化预处理,对预处理后的污泥的物理性质、水力学性质和土力学性质以及重金属存在形态等进行监测,同时通过现场试验和监测确定未经填埋的固化污泥是否达到资源化利用的标准,是否具有制作回填土及营养土的可能性.     

Evaluation for Agricultural Usage with Speciation of Heavy Metals in a Municipal Sewage Sludge

This study was carried out to evaluate the agricultural usage of an anaerobically digested sludge in the contents and fractions of heavy metals. Therefore, a sequential extraction scheme according to the BCR's (Community Bureau of Reference) guidelines and total acid digestion were applied to sewage sludge samples. The results of total heavy metal concentrations in sewage sludge showed that the highest total concentrations were Fe, Zn and Mn. When Turkish, Europe and US EPA directives were compared with each other by depending on the use of sludge for agricultural purposes, all the heavy metals determined for this sludge were below the maximum permitted levels, except for Cd. This sludge should not be applied to land due to its high Cd content. The results of heavy metal fractions indicated that some metals (Cd, Mn, Pb, and Fe) distributed mainly in the residual fraction. All fractions of Zn showed no variation. Cu and Cr were most abundant in the oxidizable phase while Ni was in exchangeable phase. Although total content of Ni in the sludge is lower than the maximum levels allowed by all the directives, it tends to be easily moved and dispersed in the environment. Due to its high mobility, the examined sewage sludge may cause phyto-toxicity after its agricultural application.     

Heterocypris incongruens as a tool to estimate sewage sludge toxicity

The toxicity of 13 sewage sludges was evaluated in relation to the crustacean Heterocypris incongruens. The bioassay used was a commercial, direct contact test that allows evaluation of solid-phase toxicity. Evaluation of sewage sludges included physicochemical properties (pH, total organic C, total N, cation-exchange capacity, total exchangeable bases, available forms of P and K, and electrical conductivity), heavy metal content (cadmium, chromium, copper, lead, nickel, and zinc), and content of polycyclic aromatic hydrocarbons (16 from the U.S. Environmental Protection Agency list). The evaluated parameters were then compared with bioassay results (mortality and growth inhibition). Sewage sludges were characterized by optimal physicochemical properties; low K (<5.64 mg/kg) and total organic C (177-253 g/kg) levels were noted. Contaminant content (heavy metals and polycyclic aromatic hydrocarbons) clearly differed between individual sewage sludges. Polycyclic aromatic hydrocarbon contents ranged from 3.8 to 36.4 mg/kg. Total concentrations of heavy metals in all sewage sludges (with the exception of one sludge) were lower than the pollutant concentration limits for land application. Heterocypris incongruens mortality when sludge was applied at doses of 6, 12, or 24% ranged from 0 to 70%, from 4.7 to 72.1%, and from 0 to 100%, respectively. Average growth inhibition was 39.7 to 46.6% (depending on the sludge dose applied). Any stimulating influence of two sewage sludges on the test organism was recorded. The median lethal concentrations calculated for individual sewage sludges ranged from 88 to 956 g sewage sludge/ kg.     

Heavy metal concentrations in soils as determined by laser-induced breakdown spectroscopy (LIBS), with special emphasis on chromium

Soil is unanimously considered as one of the most important sink of heavy metals released by human activities. Heavy metal analysis of natural and polluted soils is generally conducted by the use of atomic absorption spectroscopy (AAS) or inductively coupled plasma optical emission spectroscopy (ICP-OES) on adequately obtained soil extracts. Although in recent years the emergent technique of laser-induced breakdown spectroscopy (LIBS) has been applied widely and with increasing success for the qualitative and quantitative analyses of a number of heavy metals in soil matrices with relevant simplification of the conventional methodologies, the technique still requires further confirmation before it can be applied fully successfully in soil analyses. The main objective of this work was to demonstrate that new developments in LIBS technique are able to provide reliable qualitative and quantitative analytical evaluation of several heavy metals in soils, with special focus on the element chromium (Cr), and with reference to the concentrations measured by conventional ICP spectroscopy. The preliminary qualitative LIBS analysis of five soil samples and one sewage sludge sample has allowed the detection of a number of elements including Al, Ca, Cr, Cu, Fe, Mg, Mn, Pb, Si, Ti, V and Zn. Of these, a quantitative analysis was also possible for the elements Cr, Cu, Pb, V and Zn based on the obtained linearity of the calibration curves constructed for each heavy metal, i.e., the proportionality between the intensity of the LIBS emission peaks and the concentration of each heavy metal in the sample measured by ICP. In particular, a triplet of emission lines for Cr could be used for its quantitative measurement. The consistency of experiments made on various samples was supported by the same characteristics of the laser-induced plasma (LIP), i.e., the typical linear distribution confirming the existence of local thermodynamic equilibrium (LTE) condition, and similar excitation temperatures and comparable electron number density measured for all samples. An index of the anthropogenic contribution of Cr in polluted soils was calculated in comparison to a non-polluted reference soil. Thus, the intensity ratios of the emission lines of heavy metal can be used to detect in few minutes the polluted areas for which a more detailed sampling and analysis can be useful.     

Phytotoxicity of municipal sewage sludge composts related to physico-chemical properties, PAHs and heavy metals

The aim of the study was to determine the influence of the composting on the phytotoxicity of sewage sludge in relation to their physical-chemical properties, heavy metals and polycyclic aromatic hydrocarbons content. Four municipal sewage sludges were composted for 76 days. A Phytotoxkit Test and pot experiment with Lepidium sativum were used for bioassay. The total PAH content in sludges ranged from 3674.1 to 11236.3 microg kg(-1). Heavy metals content was in the range Cd (1.9-76 mg kg(-1)), Cr (27.6-120 mg kg(-1)), Cu (156-335 mg kg(-1)), Pb (37.5-59.5 mg kg(-1)), Ni (21.7-155 mg kg(-1)) and Zn (1015-1385 mg kg(-1)). The results showed a varied toxicity of sewage sludge in relation to the plant tested. In the case of two sludges a 100% inhibition of seed germination were noted. Sludge composting limited their negative influence on most of the phytotoxicity parameters. Only chlorophyll concentration was often lower than in the plant bred on compost obtained from sludge.     

矿化垃圾的重金属淋溶试验研究

通过土柱实验模拟矿化垃圾以及矿化垃圾与污泥混合物在淋溶条件下重金属的淋失情况,并利用污染综合指数法分析矿化垃圾中重金属迁移对地下水的影响.结果表明淋溶的不同阶段对地下水易造成污染的金属元素有所不同,需要分阶段进行监控.淋溶初期需监测[As]、[Cr]、[Co]、[Cu]和[Mn];淋溶中期需监测[Ni]和[Pb];淋溶末期需对[Fe]进行监测.综合污染指数评价表明矿化垃圾以及矿化垃圾与污泥混合土壤的淋溶液对地下水造成潜在污染的最关键因子为Mn,其次是Fe.     

Municipal sewage sludge application on Ohio farms: tissue metal residues and infections

Transmission of infectious agents and translocation of Cd, Cu, Pb, and Zn from anaerobically digested sludge to the tissues of farm animals grazing on pastures to which sludge was applied (2-10 metric tons per hectare) were studied on eight farms. No significant health risk associated with the possible presence in sludge of Salmonella spp., or of common animal parasites including Nematodirus spp., Strongylus spp., Strongyloides spp., Trichuris spp., Eimeria spp., Ascaris spp., and Ancylostomum spp. was noted. Caudal fold as well as cervical tuberculin testing indicated no conversions from negative to positive following exposure of cattle to sludge. Significantly higher fecal Cd concentrations were detected in samples collected from cattle soon after being placed on sludge-treated pastures compared to preexposure values in the same animals. Significant Cd and Pb accumulations were found in the kidneys of calves grazing sludge-treated pastures compared to control calves. Although older cows grazing sludge-treated pastures had significantly higher blood Pb levels, no metal accumulation was observed in other tissues. Statistically significant accumulations of Cd and Pb in the kidney of calves grazing these pastures for a relatively short period suggest that caution should be exercised to avoid prolonged grazing of cattle on pastures receiving heavy sludge applications, especially with sludges containing high concentrations of heavy metals.