BOD测试的动力学研究

一、引 言 污水含有社会产生的各种水载废物,除生活性质的外,常含有工业废水。污水的化学成份复杂,它的特性取决于可以测定的一些通用参数,其中最重要的是污水与氧的结合力,它随污水中存在的可氧化物质的性质和数量而变化。通常用污水的需氧量作为测定污水与氧的结合力的根据,大小用污水中存在的可氧化物质氧化所需要的氧的数量表示。污水治理的目标就是使污水的需氧量降     

德意志联邦共和国环境研究报告书

一、环境保护的出发点 在历史发展的各个阶段,人类都在以各种各样的方法影响着它周围的环境。由于工业社会的高速发展,自然平衡的形式在数量以及范围上所遭到的猛烈侵犯而造成的世界范围的重大危险正在威胁着人类。对不可更新的原料的需求量的提高以及工业化和城市化都在使生物     

煤气废水的可处理性

加利福尼亚(州)的得克萨斯研究中心进行了关于煤的气化中试工厂废水的采样和废水可处理性的研究。这些研究是为评定废水和开发废水回收系统的设计资料进行的。废水的一些分析是在现场进行的。另外的化学分析和可处理性的研究是在Westwood, New Jersey实验室进行的。 所处理的废水包括循环气体的直接冷却水和淋洗水,它们是从得克萨斯气化器在溶     

苏联生态环境的保护与研究

绪言 生态环境是指以人类为中心的生物存在与活动的空间,一切与生物有交互作用和关系的环境。生态环境研究的基本含义就是:用生态学和环境料学的观点和基本原理,来研究人类活动与人类赖以生存和发展的环境因素之间的相互关系及其发展演化的机理和规律。生态环境概念的提出,是人们对环境问题认识进一步深化的必然结果。生态环境研究的开展,标志着环境料学的研究工作已进入一个新阶段,它是进行生态建设的基础,是为建设一个经济、社会、环境三者协调、持续发展的人工复合生态大系统而探索科学规律、以便更好的指导人类的活动。生态环境研究的特点在于它的综合性,它需要宏观与微观相结合。 全球性的大生态环境的研究是当前环境科研工作的一个大趋势,是联合国环境规划署成立15年来工作积累的一个新要求,是我国环境科研工作的一个新起点。为此,中科院于198G年10月成立了中国科学院生态环境研究中心。     

我国农村分散型污水处理设施与设备性能评估体系的建立

我国农村分散型污水处理设施与设备正处于向正规化和可持续化转变的关键阶段。如何构建具有我国特色的农村分散型污水处理设施与设备的完整评估体系,真实提供科学评估后的处理效率,从而切实提高真正具有长期稳定运行能力的适用技术与设备的应用比率,这是我国当前农村分散型污水处理中亟需解决的关键问题。通过对欧、美、日等发达国家(地区)分散型污水处理设施与设备性能评估体系的系统剖析发现,这些国家在构建相关上位法律的基础上,建立标准化的评估流程与多样化的性能评估内容是评估体系能够真正发挥作用的重要保证。我国未来的评估体系应首先考虑建立合格的独立第三方评估主体,保证认证过程的公正性与评估结果的公平性;其次,认证内容方面则应坚持多元化的性能认证,引导未来分散型污水处理"因地制宜"的发展趋势;第三,提倡在标准进水及变化条件下对多类污染物的去除效率评价,体现设施运维的操作便利性,为未来可能的工艺组合中提供准确的污染物单元削减能力。我国的分散型污水处理设施与设备的评估体系的建立将为当前各项繁杂技术的比对提供统一客观依据,进一步地规范污水处理技术与设施设备的市场化选择运行,有效推广低成本、低能耗、易维护、高效率污水处理技术的实际应用,从而为农村人居环境改善中"梯次推进农村生活污水治理"的目标奠定坚实的技术评价基础。     

鸡粪制备的生物碳对水中磷的吸附去除研究

以鸡粪为原料热解制备的生物碳作为吸附剂,考察了水中磷在生物碳上的吸附动力学,以及吸附效果的主要影响因素,并对磷的去除机制做了初步探讨.结果表明:以鸡粪为原料制备的生物碳具有较高的灰分含量和较高的比表面积,这有利于其对磷的吸附;拟一级动力学模型能更好描述水中磷在生物碳表面的吸附行为,水中磷是通过吸附到生物碳表面的胶体和MgO颗粒上而得以去除的;磷在生物碳上的吸附等温线能较好用Freundlich、Langmuir-Freundlich模型来拟合,表明生物碳对磷的吸附是由非均质过程控制的;生物碳对磷的吸附作用受溶液pH的影响,这是由于pH影响溶液中磷的存在形式,而各种离子在生物碳表面的竞争吸附会影响磷的吸附效果;利用鸡粪热解产生的生物碳吸附去除水中磷是可行的,不仅成本低廉并且能够达到以废治废的目的.     

塑料包装废弃物污染现状与管理对策

塑料包装物引起的“白色污染”是近年来公众最为关注的环境问题之一。本文在对国外塑料包装物方面的立法和管理体制进行分析的基础上,结合国内塑料包装废弃物的现状,从可持续发展的角度对建立中国塑料包装废物的立法和管理框架进行了探讨。回收利用是防治“白色污染”的行之有效的方法,再辅以新材料新技术的应用,塑料包装物带来的环境问题基本可以得到解决     

酸雨的利弊

迄今,所有关于酸雨作用的资料均来自酸度增长对水族生物的影响进行的研究。pH值较低对鱼类,植物和其他的淡水系统成员的影响得到了大量资料的证实。所以对受到酸化影响的生态系统的分解方式和分解程度所作推测是相当可靠的。营养物增多带来的好处和对植物生长可能带来的抑制及其他的有害影响使得估计表现平衡对陆基生态系统的潜在效应复杂化。大多数数据是在实验室和温室条件下将陆生生物暴露在酸雨中采用模拟法获得的。因而,从这些数据所得的任何结论都可能由于从实验室延拓到现场而影响可靠性。     

渗透蒸发膜的研究现状与发展

渗透蒸发是一种新发展起来的膜分离技术,对一些有机混合物系的分离具有独特的优点,越来越受到人们的重视,近年来发展很快。 本文从四个方面介绍了渗透蒸发的研究与发展情况,首先追朔了渗透蒸发的发展历史,接着阐述了渗透蒸发过程的基本原理,包括物质通过膜的透过机理和影响渗透蒸发过程分离特性的各种因素,然后介绍了渗透蒸发膜的材料及其选择方法,包括渗透蒸发膜性能的评价方法,膜材料的选择方法和渗透蒸发过程中应用的各种材料的膜,最后介绍了渗透蒸发的工业应用。     

排污收费制度的一项重大改革

排污收费制度是根据“污染者负担”的原则制定的,排污收费运用价值规律的理论和体现经济利益的机制,强化环境管理,促进企业防治污染的一个独特的制度,是我国环境保护工作的一项重要的经济政策。征收的排污费纳入预算内,作为环境保护补助资金,按专项资金管理,实行专款专用,目前已成为治理污染最可靠的一条资金渠道,有力地促进了污染源的治理,对保护和改善环境起到了重要的作用。     

Non-controlled biogenic emissions to the atmosphere from Lazareto landfill, Tenerife, Canary Islands

GOAL, SCOPE AND BACKGROUND: [corrected] Historically, landfills have been the simplest form of eliminating urban solid waste with the minimum cost. They have been the most usual method for discarding solid waste. However, landfills are considered authentic biochemical reactors that introduce large amounts of contaminants into the environment in the form of gas and leachates. The dynamics of generation and the movement of gas in landfills depend on the input and output parameters, as well as on the structure of the landfill and the kind of waste. The input parameters include water introduced through natural or artificial processes, the characteristics of the urban solid waste, and the input of atmospheric air. The main output parameters for these biochemical reactors include the gases and the leachates that are potentially pollutants for the environment. Control systems are designed and installed to minimize the impact on the environment. However, these systems are not perfect and a significant amount of landfill gas could be released to the atmosphere through the surface in a diffuse form, also known as Non-controlled emission. In this paper, the results of the Non-controlled biogenic gas emissions from the Lazareto landfill in Tenerife, Canary Islands, are presented. The purpose of this study was to evaluate the concentration of CH4 and CO2 in the soil gas of the landfill cover, the CH4 and CO2 efflux from the surface of the landfill and, finally, to compare these parameters with other similar landfills. In this way, a better understanding of the process that controls biogenic gas emissions in landfills is expected. METHODS: A Non-controlled biogenic gas emission survey of 281 sampling sites was carried out during February and March, 2002. The sampling sites were selected in order to obtain a well-distributed sampling grid. Surface landfill CO2 efflux measurements were carried out at each sampling site on the surface landfill together with soil gas collection and ground temperatures at a depth of 30-40 cm.The CH4 efflux was computed from CO2 efflux and from the ratio CH4/CO2 in the soil gas. Soil gas samples were collected at a depth of 30-40 cm using a metallic probe and 20 cc hypodermic syringes, and later stored in evacuated 10 cc vacutainers for laboratory analysis of bulk composition. The gas sample was introduced in a vacutainer filled with deionized water and displacing the water until the vacutainer was filled with the gas sample in order to avoid air contamination from entering. The surface landfill temperature of the landfill was measured at a depth of 40 cm using a digital thermometer type OMEGA 871A. Landfill gases, CO2 and CH4, were analyzed within 24 hours using a double channel VARIAN micro-GC QUAD CP-2002P, with a 10 meter PORAPLOT-Q column, a TCD detector, and He as a carrier gas. The analysis temperature was 40 degrees C and the injection time was 10 msec. Surface landfill CO2 efflux measurements were performed using a portable NDIR spectrophotometer Licor-800 according to the accumulation chamber method (Chiodini et al. 1996). The data treatment, aimed at drawing the flux map and computing the total gas output, was based on the application of stochastic simulation algorithms provided by the GSLIB program (Deutsch and Journel 1998). RESULTS: Diffuse CH4 and CO2 efflux values range from negligible values up to 7,148 and 30,573 g m(-2) d(-1), respectively. The spatial distribution of the concentration and efflux of CO2, CH4 and soil temperature, show three areas of maximum activity in the landfill, suggesting a non-uniform pattern of diffuse degassing. This correlation between high emissions and concentration of CO2, CH4 and soil temperatures suggests that the areas of higher microbial activity and exothermic reactions are releasing CO2 and CH4 to the atmosphere from the landfill. Taking into consideration the spatial distribution of the CO2 and CH4 efflux values as well as the extension of the landfill, the Non-controlled emission of CO2 and CH4 to the atmosphere by the Lazareto's landfill are of 167 +/- 13.3 and 16 +/- 2.5 t d(-1), respectively. DISCUSSION: The patterns of gas flow within the landfill seem to be affected by boundary materials at the sides. The basalt layers have a low permeability and the gas flow in these areas is extensive. In this area, where a basalt layer does not exist, the flow gas diffuses toward the sea and the flux emissions at the landfill surface are lower. This behavior reflects the possible dissolution of gases into water and the deflection of gases towards the surface at the basalt boundary. The proximity to the sea, the installation of a palm tree garden and, as a result, the contribution of water coming from the watering of this garden has reactivated the system. The introduction of sea water into the landfill and the type of boundary could be defining the superficial gas discharges. CONCLUSIONS: Results from this study indicate that the spatial distribution of Non-controlled emission of CO2 and CH4 at the Lazareto's landfill shows a non-uniform pattern of diffuse degassing. The northeast, central and northwest areas of the Lazareto's landfill are the three areas of high emissions and concentration of CO2 and CH4, and high temperatures. The correlation between high emissions and the concentration of CO2, CH4, and the high temperatures suggest that the areas of higher microbial activity and exothermic reactions are releasing more CO2 and CH4 to the atmosphere from the landfill. A high concentration of CO2 is probably due to the presence of methanotrophic bacteria in the soil atmosphere of the landfill. Patterns of gas flow within the landfill seem to be affected by boundary materials (basalt layers) of low permeability, and side boundaries of the flux emissions at the surface are higher. At the sides of seawater and sediment boundaries, flux emissions at the landfill surface are lower. This behavior reflects a possible dissolution of gases into the water and the deflection of gases towards the surface at the basalt boundary. With this study, we can compare the data obtained in this landfill with other landfills and observe the different levels of emission. The proximity to the sea and the installation of the palm tree garden palms and, as a result, the contribution of water coming from the watering of this garden has reactivated the system. Many landfills worldwide located in similar settings could experience similar gas production processes. RECOMMENDATIONS AND PERSPECTIVES: The need for investigating and monitoring sea water and sediment quality in these landfills is advisable. Concentrations and fluxes of contaminants and their impact in the area should be assessed. With this study we can compare the data obtained in these landfills with other landfills and observe the different levels of emission.     

Anaerobic degradation of naphthalene in a fluvial aquifer: a radiotracer study

A radiotracer study was conducted in a creosote-contaminated aquifer beneath the Fraser River, British Columbia Canada to investigate the in situ degradation of naphthalene. The groundwater is anaerobic, with abundant methane, ferrous iron and carbon dioxide. This study followed earlier work at the site where the contaminant distribution could only be explained by invoking a mass loss through degradation, even though extensive field and laboratory microcosm studies closer to the source zone onshore could not confirm degradation. Accordingly, 14C-naphthalene was injected into the aquifer offshore, further from the source zone where modeling suggested degradation was occurring. During the 230-day monitoring period, 14CO2 was detected, confirming the degradation of the radio-labeled naphthalene tracer. A zero-order degradation rate of naphthalene of 5 microg/L-day was estimated based on the decrease in 14C-naphthalene concentration with time. While the degradation pathway could not be determined from the radiotracer study alone, the geochemistry of the site suggests that either iron reduction or methanogenesis is the terminal electron accepting processes responsible for naphthalene oxidation.     

Laboratory study on leachability of five herbicides in South Australian soils

Abstract

Norflurazon, oxadiazon, oxyfluorfen, trifluralin and simazine are herbicides widely used in the vineyards of the Barossa Valley, South Australia. The leaching behaviour of norflurazon, oxadiazon, oxyfluorfen and trifluralin was investigated on four key soils in the Barossa Valley. Leaching potential on packed soil columns and actual mobility using intact soil columns were investigated. On the packed soil columns, norflurazon was the most leachable herbicide. More of the herbicides were detected in the leachates from the sandy soils (Mountadam and Nuriootpa) than from the clayey soils (Lyndoch and Tanunda). Organic matter is generally low in soils in the Barossa region. Porosity and saturated conductivity significantly affect herbicide movement and in the sandy Mountadam and Nuriootpa soils, the water flux is greater than for the higher clay content Lyndoch and Tanunda soils. Increasing the time interval between herbicide application and the incidence of “rainfall”; reduced the amounts of herbicides found in the leachates. The use of intact soil columns and including simazine for comparison showed that both norflurazon and simazine were present in the leachates. Simazine was the first herbicide to appear in leachates. Sectioning of the intact soil columns after leaching clearly demonstrated that norflurazon and simazine reached the bottom of the soil columns for all soils studied. Greater amounts of norflurazon were retained in the soil columns compared with simazine. The other herbicides were mostly retained in the initial sections of the soil columns.     

Source identification of copper, lead, nickel, and zinc loading in wastewater reclamation plant influents from corrosion of brass in plumbing fixtures

A natural experiment indicated that a link between the presence and concentration of four elements, copper, lead, nickel, and zinc in the influent to two wastewater reclamation plants to the presence and concentrations of the same four elements in the tap water of residential properties. There were 36 populations of results that were assessed for the normality of their distribution, the difference in their median concentrations, the similarity in the ratios of their median concentrations, and the correlations of the concentrations. The results of this study suggest that brass corrosion is the major source of these four elements in the water reclamation plants influent and that there are two distinct populations of brass sources, those in the early stages of dezincification where the release of the non-copper elements is dominant and those in the later stages where the release of copper dominates and the type of brass that is corroding.     

Environmental assessment of ester-based lubricants after application

GOAL, SCOPE AND BACKGROUND: Lubricants based on renewable resources are an environmentally friendly alternative to petrochemical products due to their better ecotoxicological performance and their excellent biodegradability. To improve the technical performance of lubricants, and to reduce friction and wear, the use of additives is nowadays obligatory. The collaborative research center SFB 442 aims at developing environmentally acceptable lubricants that facilitate the avoidance of these additives by transferring their function to suitable coatings. For a complete assessment of the ecological performance of these newly developed lubricants, the whole life cycle including production, application as well as disposal and fate in the environment is studied. In the following study the focus was on the application and its influence on the environmental behavior of the lubricant. The application of lubricants leads, among other things, to the intake of metals due to abrasion from tools, work pieces or mechanical components. Previous examinations indicated a possible influence of metals on the toxicity of eluates prepared from used lubricants (Erlenkaemper et al. 2005). To clarify if the apparent toxicity of used lubricants solely results from the intake of metals, the extractability of these metals from the oil matrix is determined. By combining chemical analyses with bioassays, the bioavailability of metals that are present in the extract is estimated. To further investigate the relevance of metals on toxicity, toxic units (TU) were calculated and related to the results of the bioassays. Interactions between the metals were investigated with aqueous mixtures of metal chlorides and calculations based on the concept of concentration addition and independent action. METHODS: A lubricant mixture was applied to a tribological test bench that simulates real conditions of use and extremely short time load, respectively. Samples were taken at particular times, water soluble fractions (WSF) of these fluids were prepared and dilution series were investigated in several bioassays. Concentration of metals and total organic carbon (TOC) were determined in the eluates. TUs were calculated according to Sprague (1970) and mixture toxicity was calculated according to the concept of concentration addition (Loewe and Muischnek 1926) and independent action (Bliss 1939). RESULTS: Analyses of the metal content of the lubricant and the eluates clearly revealed the availability of the metals in the aqueous extracts. Especially copper, zinc, nickel and chromium were found and their concentrations increased during the time of use. The water extractable fraction, e.g., of copper, rose from 8.8% to 45.3% of the total content in the lubricant after 33.5 hours of use. Tests performed with the algal growth inhibition assay and the luminescence inhibition assay revealed the uptake or absorption by the organisms and, thus, the bioavailability of the metals. The calculation of TUs partly indicated a possible influence of the metals on ecotoxicity of the eluates. Copper reached concentrations equal to or higher than the EC50 value of copper chloride in the growth inhibition assays with algae and Ps. putida as well in the immobilization assay with daphnids. TUs for copper are also larger than 1 for the algal growth inhibition assay. The EL50 values indicated that the luminescence inhibition assay was the most sensitive test system, with values between 4.7% and 9.6%. While the toxicity towards algae and V. fischeri in the growth inhibition assay decreased until both organisms were no longer influenced by the exposure, the EL50 values for the D. magna immobilization assay and the Ps. putida growth inhibition assay decreased with the progressing use of the lubricant. The tested metal salt mixtures showed that Ps. putida, algae and daphnids are the most sensitive organisms with EC50 values below 1 mg/l. DISCUSSION: Although the intake of metals mainly occurred via abrasion of particles, the results revealed the availability of these metals in water. The availability varied for each of the four metals. For both the algal growth inhibition assay and the luminescence inhibition assay, an uptake or absorption of the metals could be demonstrated. The calculated TUs indicated an effect in some bioassays that was not verified in the test itself. The influence of copper on V. fischeri, for example, was not confirmed while the EL50 values for the daphnid bioassay decreased, meaning that the eluates became more toxic with progressing use of the lubricant. The calculations of mixture toxicity based on the concept of concentration addition demonstrated good correlations with the tested metal mixtures, but also a different sensitivity of the organisms. CONCLUSIONS: The results presented here reveal the availability of those metals in water that were taken in during the use of the lubricant in a tribological test bench and, thus, have the possibility of interacting with the organisms. The availability of the metals in the bioassays was proven by chemical analyses. The calculation of TUs and the corresponding EL50 values, however, indicate different availabilities of the metals. The results of the metal salt mixtures show good correlations with calculations of mixture toxicity based on concentration addition. Moreover, the varying sensitivity of the organisms when exposed to eluates or metal mixtures indicates a different bioavailability of the metals and/or the presence of other compounds that exert toxic action. RECOMMENDATIONS AND PERSPECTIVES: For further investigations, the organic oil matrix and its influence on the toxicity have to be taken into account. The toxicity of the eluates may not only be due to metals; additional effects could arise from changes in the lubricant itself.     

Modeling the spill in the Songhua River after the explosion in the petrochemical plant in Jilin

An explosion in a petrochemical plant in Jilin in the northeast of China on 13 November 2005 was responsible for the discharge of large quantities of benzene and nitrobenzene into Songhua River. This endangered the water supply of Harbin city and influenced the daily life for millions of people. The dispersion-advection equation was solved analytically and numerically and used to simulate the concentration of benzene and nitrobenzene in the Songhua River after the accident. Both solutions gave practically identical results. The main elimination process for both compounds was volatilization. The model results are quite close to the results obtained by measurements at monitoring stations. Arrival time of the pollutant wave, peak concentrations and end of the pollutant wave at Harbin and along the river were predicted successfully. The peak concentrations of nitrobenzene at Harbin were more than 30 times above the permissible limits for drinking water.     

The occurrence of antihistamines in sewage waters and in recipient rivers

Background, aim and scope  Each year, large quantities of pharmaceuticals are consumed worldwide for the treatment and prevention of human and animal diseases. Although the drugs and the metabolites observed in the wastewaters and in the environment are present at concentrations several orders of magnitude lower than the concentrations required to exert their effects in humans or animals, their long-term impact on the environment is commonly not known. In this study, the occurrence of six antihistamines, which are used for the relief of allergic reactions such as hay fever, was determined in sewage treatment plants wastewaters and in recipient river waters. Materials and methods  The occurrence of the antihistamines cetirizine, acrivastine, fexofenadine, loratadine, desloratadine and ebastine in sewage treatment plants wastewaters and in recipient river waters was studied. The analytical procedure consisted of solid-phase extraction of the water samples followed by liquid chromatography separation and detection by a triple-quadrupole mass spectrometer in the multiple reaction mode. Results  Cetirizine, acrivastine and fexofenadine were detected in both influent and effluent wastewater samples at concentration levels ranging from about 80 to 220 ng/L, while loratadine, desloratadine and ebastine could not be detected in any samples. During sewage treatment, the concentration of the antihistamines dropped by an average of 16–36%. Furthermore, elevated concentrations of antihistamines were observed in samples collected during the season of most intensive plant pollen production, i.e. in May. In the river water samples, the relative pattern of occurrence of cetirizine, acrivastine and fexofenadine was similar to that in the wastewater samples; although the concentration of the compounds was substantially lower (4–11 ng/L). The highest concentrations of the studied drugs were observed near the discharging point of the sewage treatment plant. Discussion  The highest concentrations of antihistamines in STP wastewaters correlate with the outbreak of allergic reaction caused by high amounts of plant pollens in the air. The analysis results of the river water samples show that the antihistamines are carried far away from the effluent discharge points. They may account for a part of the mix of pharmaceuticals and of pharmaceutical metabolites that occur downstream of STPs. Conclusions  Antihistamines are poorly degraded/eliminated under the biological treatment processes applied in the wastewater treatment plants and, consequently, they are continuously being discharged along with other drugs to the aquatic environment. Recommendations and perspectives  As a huge quantity and variety of drugs and their metabolites are continuously discharged to rivers and the sea, the compounds should be considered as contaminants that may possess risks to the aquatic ecosystem. Further studies are urgently needed on the environmental fate of the antihistamines and other pharmaceuticals in the aquatic environment. These studies should be concerned with the stability of the compounds, their transformation reactions and the identity of the transformation products, the distribution of drugs and their uptake and effects in organisms. On the basis of these studies, the possible environmental hazards of pharmaceuticals may be assessed.     

Butyltin compounds in sediment and fish from the Polish Coast of the Baltic Sea

Concentrations of mono- (MBT), di- (DBT), and tri-(TBT) butyltin compounds were measured in eggs, liver, and muscle of nine species of fish from four regions of the Baltic Sea - the Firth of Vistula, the Gulf of Gdańsk, Puck Bay, and the mouth of the Vistula River. The overall concentration ranges among all the fish sampled from the four sites were: < 7 to 79 ng/g for MBT, 6 to 1100 ng/g for DBT, 7 to 3600 ng/g for TBT, and 16 to 4800 ng/g for total BTs, on a wet wt basis. The highest concentration of total BTs was found in herring liver from the Firth of Vistula (4800 ng/g, wet wt) and in roach muscle from Puck Bay (3300 ng/g, wet wt), while the least concentration was found in burbot eggs and liver from the Vistula River (39 and 32 ng/g, wet wt, respectively). TBT was the major form of BTs present in most samples analyzed. Sediment samples collected from shipyards in the Gulf of Gdańsk contained butyltin concentrations ranging from 1.2 to 46 μg/g (dry wt) for MBT, 2.0 to 42 μg/g for DBT, and 2.6 to 40 μg/g for TBT. As with the fish, the majority of the BTs in sediment were present as TBT, which suggested recent exposure of the aquatic environment of the region to TBT.     

Anaerobic digestion of linear alkyl benzene sulfonates: biodegradation kinetics and metabolite analysis

In the present work the effect of the alkyl chain length and the position of the sulfophenyl substituent of the linear alkylbenzene sulfonates (LAS) on their anaerobic biodegradability have been investigated. Degradation kinetics of the linear alkyl benzene sulfonates homologues, 2C₁₀LAS, 2C₁₂LAS and 2C₁₄LAS, have been studied. It has been also investigated the effect of the isomer type on the degradation rate of the LAS molecule through the comparative study of the 2C₁₀LAS and 5C₁₀LAS isomers. Batch anaerobic biodegradation tests were performed using sludge from the anaerobic digester of a wastewater treatment plant as microorganisms source. Ultimate biodegradation was evaluated from the biogas production whereas primary biodegradation was determined by specific analysis of the surfactant. LAS homologues and isomers showed a negligible primary biodegradation under anaerobic conditions. Furthermore, analysis of sulfophenyl carboxilates (SPC) by LC–MS indicated a low and constant level of these LAS degradation metabolites over the test period. These data are consistent with a minimal transformation of the LAS parent molecule in the anaerobic digesters. On the other hand, the addition of the shortest alkyl chain length homologues, decyl and dodecylbenzene sulfonates, reduces the biogas production whereas the most hydrophobic homologue, the tetradecylbenzene sulfonate, enhances the biogas production. This LAS homologue seems to increase the availability of organic compounds sorbed on the anaerobic sludge promoting their biodegradation.     

A History of Dry Cleaners and Sources of Solvent Releases from Dry Cleaning Equipment

Approximately 25, 000-35, 000 dry cleaning facilities currently operate in the U.S. The release of perchloroethylene and other solvents from these establishments represents a major source of soil and groundwater contamination. The manner in which dry cleaning solvents escape from dry cleaning plants is, for all practical purposes, identical for chlorinated and petroleum hydrocarbon solvents and is related to one of the following events: the catastrophic failure of a component of the dry cleaning system, the improper installation, operation or maintenance of the dry cleaning equipment or a combination of all of these causes. Acceptable customs, codes and regulations can also dictate what is authorized for operation of a dry cleaning facility in a particular community, geographic area during a particular time frame. Environmental litigation dealing with the origin of a solvent release from dry cleaners tends to focus on the design and manufacture of dry cleaning industry machines such as washers, washer extractors, tumblers, solvent filters, water separators, stills and spotting boards. A thorough analysis of the daily operations of dry cleaners often reveals that poor maintenance, failure to follow the manufacturer's instructions and the actions of the operator are the most likely causes of soil and groundwater pollution. In order to forensically evaluate the most probable origins of a solvent release and to examine issues regarding liability, a thorough understanding of the history of dry cleaning and a detailed analysis of the operation and maintenance of the dry cleaning equipment are necessary. The discovery of solvent plumes in the vicinity of dry cleaning plants may suggest that the solvent source is the dry cleaning plant; however, the presence of these plumes does not necessarily indicate that the dry cleaning equipment was defectively designed or manufactured. A thorough review of the type of equipment used over the life of the dry cleaning plant and verifiable solvent mileage records frequently indicates that operators of the plant have disposed of solvent and contaminated solids into the municipal sewer or on ground surfaces.