铁炭微电解预处理高浓度高盐制药废水

采用铁炭微电解法预处理高浓度高盐制药废水,并对反应条件、处理效果、反应动力学和机理进行研究。通过单因素实验初步研究进水pH、铁用量、反应时间和铁炭比对处理效果的影响;通过正交实验表明进水pH对处理效果影响最大,并得到最佳反应条件为:进水pH为4.5,铁投加量40 g/L,铁炭质量比1∶1,反应时间4 h,COD去除率可达40%以上,并可以提高废水的可生化性,后续通过厌氧生物处理出水可达二级污水综合排放标准。通过对各级反应动力学方程进行回归分析,表明微电解处理制药废水基本遵循一级反应动力学。铁炭微电解处理制药废水效果好,并可以提高可生化性,同时具有操作简单和成本低的优点,为制药废水的预处理提供新的途径。     

铁炭微电解/Fenton试剂预处理土霉素废水的研究

研究了铁炭微电解/Fenton试剂法工艺对高浓度难生化处理的土霉素废水预处理效果.结果表明,当原水COD在6 000 mg/L、pH值为2.2时,铁炭微电解反应时间为80 min,铁炭微电解对原水COD的去除率>40%;铁炭微电解出水再投加220 mg/L的H2O2(30%)进行Fenton试剂法处理,常温下反应50 min对原水COD的去除率可提高到75%以上.铁炭微电解 Fenton试剂联合工艺的处理效果好、运行稳定、成本低廉,适宜对难降解的土霉素废水的预处理.     

铁炭微电解预处理电路板废水

采用铁炭微电解法预处理电路板废水.结果表明,在进水pH为2.00、铁炭质量比为4:1、振荡时间为20 min的铁炭微电解静态实验最佳条件下,絮凝出水COD去除率为30%;在进水pH为2.00、铁炭质量比为4:1、水力停留时间为50 min的铁炭微电解柱动态实验最佳条件下,连续曝气.絮凝出水COD为11021 mg/L,COD去除率约为34%,BOD5/COD从0.12上升到0.32,可生化性提高,Cu2+质量浓度从9.11 mg/L下降至0.76 mg/L,降低了废水的生物毒性,为生化处理创造了条件.     

铁炭微电解-水解酸化-接触氧化法处理有机硅废水的研究

针对有机硅废水的特性,采用铁炭微电解预处理、水解酸化和接触氧化组合工艺处理有机硅废水。废水经铁炭微电解预处理后COD去除率达40%;水解酸化处理后COD去除率达30%;接触氧化处理后COD去除率达70%;当系统进水COD为750 mg/L时,经过组合工艺处理后,出水COD可降至100 mg/L以下,达到了工业废水排放标准。     

铁炭微电解法预处理超高盐榨菜腌制废水

超高盐榨菜腌制废水是高盐、高氮磷及高有机物废水，目前常采用生物方法进行处理，但因高污染物浓度及高盐度影响，处理效果不够理想；因此，选用铁炭微电解法对超高盐榨菜腌制废水进行预处理。通过静态烧杯实验，研究了反应时间、初始pH、铁炭体积比和铁水体积比对COD和氨氮去除率的影响。单因素实验的最佳处理条件：原水pH4～4．5，反应时间为30min，铁炭体积比为1：1，铁水体积比为2：1，出水COD和氨氮的去除率分别为57．29％和53．11％，盐度由原水的6．62％下降为3．63％，去除率达45．17％，pH由原水4．01升高为6．38。正交实验结果表明，影响COD和氨氮去除率的因素从大到小的顺序为：铁水体积比、初始pH、反应时间、铁炭体积比。实验表明，采用铁炭微电解法能够对超高盐榨菜腌制废水中的COD和氨氮进行有效去除，出水的pH升高和盐度下降，能满足后续生物处理的预处理要求。     

微电解-混凝法处理抛光液废水

采用微电解-混凝处理抛光液废水,考察了铁水比、进水pH值、铁炭比、振荡时间对微电解处理效果的影响.通过单因素实验与正交实验找出了影响较大的因素,进水pH、铁水比、振荡时间都对去除率影响较大.最佳微电解条件为铁水比为0.375,进水pH为3,铁炭比为1∶1,振荡时间为150 min.同时,当混凝剂硫酸亚铁的投加量为160 mg/L、三氯化铁的投加量为20 mg/L时,COD去除率可达到83.8％,金属铜离子去除率可达到96％.     

电絮凝处理牛仔布印染废水

用铁分别作为电絮凝反应系统的阴极和阳极,研究电絮凝法对牛仔布印染废水的处理效果。考察了电极电压、反应时间和pH等因素对电絮凝法去除实验所用废水中COD和色度效果的影响。结果表明,电极电压和反应时间是主要的影响因素,pH次之。电极电压24 V,反应时间35 min,pH为7.4时,脱色率可达99%,COD去除率在70%左右,处理效果最佳。因此,电絮凝法可以作为印染废水的预处理工艺,有效降低废水COD和色度。     

铁炭微电解-Fenton试剂法预处理半焦废水

采用铁炭微电解／Fenton试剂法对半焦废水进行预处理，探索材料粒径、铁炭比、废水pH、H2O2用量以及反应时间对处理效果的影响。结果表明，在铁屑粒径为5～7mm，活性炭粒径为2～3mm，铁炭体积比为1：1，微电解反应90min，进水pH为8．0～9．0，H2O2投加量为4mL／L，Fenton试剂反应90min的条件下，半焦废水COD去除率可达55％以上，B／C由处理前的0．24提高到0．43，可生化性能良好，铁炭微电解／Fenton试剂法可作为半焦废水一种有效的预处理方式。     

铁炭微电解法降解TAIC废水

TAIC（三烯丙基异氰脲酸酯）作为过氧化物交联或自由基反应交联的助交联剂被广泛应用。由于TAIC性质稳定难于生物降解，采用铁炭微电解法处理TAIC生产废水，并考察了铁炭比、进水pH值、反应时间对处理效果的影响，以及TAIC降解机理和反应动力学过程。结果表明，影响微电解工艺的因素主次关系为：pH>Fe/C质量比>反应时间；在最佳条件进水pH值为5，铁炭质量比为2：1，反应时间为135 min时，COD的去除率达到46%以上，TAIC的去除率达到48%以上。TAIC去除机理研究表明，微电解对TAIC废水的作用主要通过·H的还原和铁离子的絮凝作用，其中·H的还原作用是TAIC降解的主要原因。反应动力学分析表明，铁炭微电解法处理TAIC的降解过程基本符合二级反应动力学规律，通过建立模型并拟合出了TAIC降解的二级反应动力学方程。     

铁炭微电解深度处理焦化废水的研究

采用曝气铁炭微电解工艺对焦化废水进行了深度处理.结果表明,在活性炭、铁屑和NaCl投加量分别为10 g/L、30 g/L和200 mg/L的条件下反应240 min,出水COD去除率在30%～40%;酸性条件可以进一步提高COD去除率;微电解可以去除原生化出水中的难降解有机物,出水物质的分子量主要集中于2000 Da以下,以脂类和烃类化合物为主;出水的可生化性有了大幅度提高,BOD5/COD由0.08增加到0.53.实验结果表明,铁炭微电解是深度处理焦化废水的一种有效工艺.     

Evaluation of trichloroethene recovery processes in heterogeneous aquifer cells flushed with biodegradable surfactants

The ability of two biodegradable surfactants, polyoxyethylene (20) sorbitan monooleate (Tween 80) and sodium dihexyl sulfosuccinate (Aerosol MA), to recover a representative dense non-aqueous-phase liquid (DNAPL), trichloroethene (TCE), from heterogeneous porous media was evaluated through a combination of batch and aquifer cell experiments. An aqueous solution containing 3.3% Aerosol MA, 8% 2-propanol and 6 g/l CaCl(2) yielded a weight solubilization ratio (WSR) of 1.21 g TCE/g surfactant, with a corresponding liquid-liquid interfacial tension (IFT) of 0.19 dyn/cm. Flushing of aquifer cells containing a TCE-DNAPL source zone with approximately two pore volumes of the AMA formulation resulted in substantial (>30%) mobilization of TCE-DNAPL. However, a TCE mass recovery of 81% was achieved when the aqueous-phase flow rate was sufficient to displace the mobile TCE-DNAPL toward the effluent well. Aqueous solutions of Tween 80 exhibited a greater capacity to solubilize TCE (WSR=1.74 g TCE/g surfactant) and exerted markedly less reduction in IFT (10.4 dyn/cm). These data contradict an accepted empirical correlation used to estimate IFT values from solubilization capacity, and indicate a unique capacity of T80 to form concentrated TCE emulsions. Flushing of aquifer cells with less than 2.5 pore volumes of a 4% T80 solution achieved TCE mass recoveries ranging from 66 to 85%, with only slight TCE-DNAPL mobilization (<5%) occurring when the total trapping number exceeded 2 x 10(-5). These findings demonstrate the ability of Tween 80 and Aerosol MA solutions to efficiently recover TCE from a heterogeneous DNAPL source zone, and the utility of the total trapping number as a design parameter for a priori prediction of DNAPL mobilization and bank angle formation when flushing with low-IFT solutions. Given their potential to stimulate microbial reductive dechlorination at low concentrations, these surfactants are well-suited for remedial action plans that couple aggressive mass removal followed by enhanced bioremediation to treat chlorinated solvent source zones.     

The variation of street air levels of PAH and other mutagenic PAC in relation to regulations of traffic emissions and the impact of atmospheric processes

The occurrence of particle associated PAH and other mutagenic PAC was determined in 1996 in the street air of Copenhagen. In addition, particle extracts were tested for mutagenicity. The measurements were compared with previous measurements in 1992/1993. The levels had decreased in this period. The decrease was caused by an implementation of light diesel fuels for buses and the exchange of older petrol-driven passenger cars with catalystequipped new ones. About 65% of the reduction was caused by the application of the light diesel fuels. Under special conditions, chemical processes in the atmosphere produced many more mutagens than the direct emissions. The concentrations of S-PAC and N-PAC were 10 times lower than those of PAH, while the levels of oxy-PAH were in the same order of magnitude as those of PAH. Benzanthrone, an oxy-PAH, is proposed to be formed in the atmosphere in addition to direct emissions. Benzo(a)pyrene, often applied as an air quality criteria indicator, was photochemically degraded in the atmosphere. A strong increase in the mutagenic activities was observed to coincide with a depletion of benzo(a)pyrene.     

Chloroaromatic pollutants in mussels incubated in two finnish watercourses polluted by industry

Concentrations of different chlorinated compounds were measured in mussels incubated in two polluted watercourses, a river (the River Kymijoki) and a lake (Lake Vanaja) for four weeks in summer 1995. The sum concentrations of polychlorinated phenols (PCP) and biphenyls (PCB) were both about 1 μg/g lipid weight (lw) in Lake Vanaja mussels, while in the River Kymijoki mussels PCPs were non-detectable and PCBs were measured 120 ng/g lIw. The concentrations of toxic polychlorinated dibenzo-p-dioxin (PCDD) and dibenzofuran (PCDF) congeners ranged between <17 and 370 pg/g Iw in Lake Vanaja mussels and between <38 and 11,000 pg/g lw in the River Kymijoki mussels. Polychlorinated diphenyl ethers (PCDE) were detected in the mussels incubated in the River Kymijoki (0.4–1.1 ng/g Iw), but not in those incubated in Lake Vanaja. Polychlorinated phenoxyanisoles (PCPA) were measured 33 ng/g lw and polychlorinated phenoxyphenols (PCPP) 300 ng/g lw in the mussels incubated in the River Kymijoki. PCPAs were also detected in reference samples, which were sediment and pike from the River Kymijoki and Baltic salmon, seal and white-tailed sea eagle.     

Teratological effects of pesticides in vertebrates: a review

Abstract

In the last decades, the use and misuse of pesticides in the agriculture have increased, having a severe impact on ecosystems and their fauna. Although the various effects of pesticides on biodiversity have been already documented in several studies, to our knowledge no consistent overview of the impact of pesticides in vertebrates, both terrestrial and aquatic, is available. In this review, we try to present a concise compilation of the teratogenic effects of pesticides on the different classes of vertebrates – mammals, birds, reptiles, amphibians and fish.     

Book review

The Pesticide Manual ‐ A World Compendium, 8th Edition, C.R. Worthing, Editor and S.B. Walker, Assistant Editor, British Crop Protection Council, BCPC Publications Sales, Bear Farm, Binfield, Bracknell, Berkshire RG12 5QE, England. 1987, 1100 pp., UK £50; Overseas £56. ISBN 0–948404–01–9.     

Patterns of volatile metabolites and nonvolatile trichothecenes produced by isolates of <Emphasis Type="Italic">Stachybotrys,Fusarium, Trichoderma,Trichothecium</Emphasis> and <Emphasis Type="Italic">Memnoniella</Emphasis>

We reported previously that trichodiene, a volatile trichothecene derivative, was produced by a Stachybotrys isolate, also known to produce highly cytotoxic, non-volatile, macrocyclic trichothecenes (satrotoxins). We investigated the relationship between the production of trichodiene and various non-volatile trichothecenes for several molds. Volatile metabolites were concentrated by adsorption on Tenax TA and analyzed by GC/MS, while non-volatile metabolites were separated by HPLC, derivatized and analyzed by GC/MS. Stachybotrys chartarum isolates producing macrocyclic trichothecenes secreted significantly larger amounts of trichodiene and other sesquiterpenes than isolates which only produced simple trichothecenes. The amounts of secreted trichodiene were relatively small in all cases. With the exception of Memnoniella, which excreted small amounts of sesquiterpenes, the other isolates produced varying amounts of sesquiterpenes, including trichodiene, as well as simple tricothecenes, no detectable trichodiene, but large amounts of griseofulvin derivatives. In Stachybotrys there is apparently a correlation between trichodiene and macrocyclic trichothecene production. In the remaining isolates, there was no simple relationship between trichodiene and non-volatile trichothecene synthesis. Trichodiene is produced in larger amounts by Stachybotrys isolates, which also produce satratoxins, but it will be difficult to utilize this metabolite to detect toxic isolates in buildings due to the relatively small amounts excreted.     

Knowledge transfer initiative between molecular biologists and environmental researchers and regulators

A Natural Environment Research Council (NERC) funded Knowledge Transfer (KT) workshop was held in the United Kingdom (UK) to identify the needs and opportunities in the application of molecular biology and ‘omics’ techniques to environmental monitoring and risk assessment. Attendees highlighted a lack of effective communication between end-users and researchers as well as difficulties with data interpretation as reasons behind the slow uptake of molecular biology and omics techniques. A number of promising areas in which new techniques could be implemented at a practical level in the very near future were identified, thereby raising the profile of these recent technologies and providing vital proof of concept work. Molecular taxonomy, bacterial source tracking and pre-screening of chemicals for potential toxicities were all viewed as areas in which omics and molecular techniques could have immediate value, with the aim of reducing cost, increasing efficiency and providing more comprehensive data of improved quality.     

The chemical stability of formulations of some hydrolyzable insecticides in aqueous mixtures with hydrolysis catalysts

Abstract

The active ingredients in commercial formulations of malathion, oxamyl, carbaryl, diazinon, and chlorpyrifos diluted to “spray tank”; concentrations with buffered distilled or natural water of pH 4–9 were stable for at least 24 hr. Formulations of trichlorfon were not stable at pH 7 or above but disappearance rates were slower than for the pure chemical in homogeneous solution. Cupric ion was observed to be an effective catalyst for the hydrolysis of a variety of pure organophosphorus insecticides but did not catalyze hydrolysis of the active ingredients of the formulations examined. Increasing the dilution of the formulation increased the susceptibility of malathion, oxamyl, and carbaryl to hydrolysis.     

Organochlorine compounds in a three-step terrestrial food chain

The concentrations of 15 organochlorine chemicals (PCBs and pesticides) were studied in a Central European oak wood food chain system: Great tit (Parus major), caterpillars (Tortrix viridana, Operophtera brumata, Erannis defoliaria), and oak-leaves (Quercus robur). Juvenile tits receive organochlorines from the mother via egg transfer and, eventually to a greater extent, from the caterpillar food source during nestling period. The concentrations of PCB 153 (2,2′,4,4′,5,5′-hexachlorobiphenyl, the most abundant in this study) was found in leaf material at ca. 1 ng/g, in caterpillars 10 ng/g, and in bird eggs 170 ng/g on an average and on a dry mass basis.     

Sorption and predicted mobility of herbicides in Baltic soils

This study was undertaken to determine sorption coefficients of eight herbicides (alachlor, amitrole, atrazine, simazine, dicamba, imazamox, imazethapyr, and pendimethalin) to seven agricultural soils from sites throughout Lithuania. The measured sorption coefficients were used to predict the susceptibility of these herbicides to leach to groundwater. Soil-water partitioning coefficients were measured in batch equilibrium studies using radiolabeled herbicides. In most soils, sorption followed the general trend pendimethalin > alachlor > atrazine～ amitrole～ simazine > imazethapyr > imazamox > dicamba, consistent with the trends in hydrophobicity (log K_ow) except in the case of amitrole. For several herbicides, sorption coefficients and calculated retardation factors were lowest (predicted to be most susceptible to leaching) in a soil of intermediate organic carbon content and sand content. Calculated herbicide retardation factors were high for soils with high organic carbon contents. Estimated leaching times under saturated conditions, assuming no herbicide degradation and no preferential water flow, were more strongly affected by soil textural effects on predicted water flow than by herbicide sorption effects. All herbicides were predicted to be slowest to leach in soils with high clay and low sand contents, and fastest to leach in soils with high sand content and low organic matter content. Herbicide management is important to the continued increase in agricultural production and profitability in the Baltic region, and these results will be useful in identifying critical areas requiring improved management practices to reduce water contamination by pesticides.