减压蒸馏耦合微电解处理六硝基芪二段洗水

通过对六硝基芪（HNS）生产过程中第二段工艺的产品洗涤废水进行水质分析,针对该段废水含有大量吡啶和多种溴代和硝基芳香类化合物的特点,探究了减压蒸馏耦合锌碳微电解法处理二段洗水的效果并优化工艺参数。结果显示,70℃条件下,二段洗水蒸馏至原体积的86．9％时,蒸馏剩余废水TOC去除率为44％,并且此前收集的馏分中吡啶浓度为10％～31．9％（V/V）。减压蒸馏工艺起到收集吡啶同时降低废水TOC的双重作用。减压蒸馏后,残留在废水中的有机物以溴代和硝基芳香化合物为主,采用微电解工艺,其条件优化实验的结果显示,在废水初始pH=1．0,锌投加量为25g／L,锌碳投加比为1：1,反应60min后,废水TOC去除率为33％,采用多级微电解工艺可提高去除效果。     

含吡啶有机废水物化预处理工艺

对含吡啶有机废水进行分类收集,分质处理,确定了蒸发脱盐-微电解-芬顿氧化预处理工艺路线。实验表明,蒸发脱盐阶段,pH值为5时,COD去除率达62.77%;微电解阶段,pH值为4、反应时间为2.5 h时,COD去除率达24.49%;Fenton试剂氧化阶段,pH值为4,30%H2O2投加量为3.5 ml/L,Fe2+与H2O2摩尔比为1∶20,反应时间为2.5 h时,COD去除率达30.41%。经预处理,废水B/C比从0.075上升至0.48,3种特征吡啶的去除率均达到95%以上。     

铁碳微电解/H_2O_2耦合类Fenton法预处理高浓度焦化废水

采用铁碳微电解/H_2O_2耦合类Fenton法预处理高浓度焦化废水,通过正交和单因素实验研究了废水初始pH、不同质量的微电解填料、H_2O_2投加量及反应时间对COD处理效果的影响,同时研究了COD降解动力学。结果表明:最佳控制条件是废水初始pH为3、铁碳填料投加量为300 g/L、H_2O_2投加量为80 m L/L、反应时间为160 min,此时COD的去除率达到87%以上;H_2O_2的加入可使铁碳微电解/H_2O_2系统COD的去除率提高37.34%,铁碳微电解/H_2O_2系统COD反应动力学方程为y=0.5296x-0.6218,相关系数R~2为0.9917。     

Fenton氧化与铁炭微电解组合预处理DMF废水

对COD表征模拟废水中DMF去除率的可行性进行了探讨。在此基础上,分别对铁炭微电解、Fenton氧化-铁炭微电解和铁炭微电解-Fenton氧化组合工艺对DMF废水的处理效果进行分析,结果表明,Fenton氧化-铁炭微电解工艺的处理效果较好。在pH=5,反应时间为1 h,FeSO4·7H2O投加量为1 000 mg/L、H2O2投加量为2.67 mL/L和不曝气的最佳反应条件下,Fenton氧化-铁炭微电解工艺对实际废水和废液中COD的去除率分别达到66.67%和72.22%,从而验证了该工艺处理DMF废水的可行性。此外,Fenton氧化处理DMF废水过程实际上是将酰胺基团和羰基的不饱和双键氧化分解的过程。     

微电解-Fenton联合工艺预处理煤层气井压裂废水

利用Fenton强化微电解工艺对煤层气井压裂废水展开预处理研究,以COD去除率和可生化性(B/C)为考察指标,单独工艺正交实验结果表明pH为3、反应时间为90 min、铁碳体积比为1.5∶1和pH为4、反应时间为80 min、H2O2投加量为4 mL/L分别是微电解与Fenton反应的最优条件,各可获得48.1%和44.9%的COD去除率。在最优条件下进行微电解-Fenton联合运行实验,连续61 h内COD去除率均稳定在65%以上,B/C由0.158上升到0.3以上,有利于后续生化处理的运行。     

铁碳微电解与微生物共作用降解BDE-209

BDE-209是世界上应用最为广泛的溴代阻燃剂之一,同时也是环境介质中普遍存在的一类强亲脂性、高生物累积性的持久性有机污染物。鉴于其生物难降解特性,尝试采用铁碳微电解技术强化其微生物降解。研究中,首先采用单因素实验确定了反应体系的铁粉最佳投加量(0.1 g)及最佳的铁碳比(1∶1),进而探讨了铁碳微电解体系促进BDE-209脱溴的降解机制。铁碳微电解体系处理BDE-209时,体系中p H及ORP值有明显的波动,反应120 h后降解率达53.0%;而铁碳微电解体系与微生物共作用体系中,120 h后BDE-209降解率可达到77.5%,降解产物主要为九溴、八溴以及七溴等低溴代联苯醚。实验结果表明,铁碳微电解与微生物共作用能够有效提高BDE-209的生物降解效率。     

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.     

微纳米气泡协同铁碳微电解工艺处理盐酸四环素废水

采用微纳米气泡联合铁碳微电解法处理盐酸四环素废水,用XRD和FT-IR对铁碳材料反应前后的结构进行了表征,研究了不同反应时间、铁碳投加量、pH、微纳米气泡进气量对盐酸四环素去除率的影响和一级反应动力学的特征。结果表明:微纳米气泡对铁碳微电解有显著的协同作用;当反应时间为120 min、铁碳投加量为100 g·L-1、pH=3、微纳米气泡进气量为30 mL·min-1时,浓度为20 mg·L-1的盐酸四环素降解效果达到最佳,降解率为80.84%,TOC去除率为47.89%。通过LC-MS测定分析,盐酸四环素经过分解转化为m/z=194、m/z=181和m/z=174的产物,并最终转化分解为CO2和H2O。以上研究结果可为抗生素废水处理提供有益的参考。     

响应面法优化Fenton试剂法处理槟榔废水

本实验研究了Fenton试剂法处理槟榔废水的工艺条件。基于Box-Behnken响应曲面法,考察了初始p H值、双氧水投加量、硫酸亚铁投加量和反应时间的单独作用和交互作用,并建立了TOC去除率数学模型。实验表明,在初始p H值为5,双氧水投加量为50 mg/L,硫酸亚铁投加量为12.5 g/L,反应时间为120 min,0.2%PAM加入量为0.2 m L时,整个反应过程对TOC去除率可达到64.1%。通过Box-Behnken响应曲面可知,双氧水投加量、硫酸亚铁投加量的交互作用对TOC去除率有显著影响,其中双氧水投加量对TOC去除率的影响极显著。Fenton试剂处理槟榔废水最佳的工艺条件为:双氧水投加量为54.2 m L/L,硫酸亚铁投加量12.55 g/L,初始p H值为4.98,反应时间为103.5 min。在此条件下TOC去除率为70.18%。     

两级预处理/MBR工艺处理制药废水

湖北西北部某工业园已建成污水处理厂(反应沉淀/水解酸化/MBR工艺)以处理合成制药废水为主,由于其预处理段处理效果难以满足后续MBR工艺要求,导致出水水质不能达到国家相关标准,急需升级改造。针对该合成制药废水污染物成分复杂、污染当量大、冲击负荷高、可生物降解性差以及水量水质变化大等特点,采用铁碳微电解/水解酸化两级预处理工艺对该制药废水进行强化预处理,并建立两级预处理/MBR工艺进行小试实验,实验结果表明,铁碳投加量为400g·L~(-1),铁碳质量比为4∶5,HRT=3 h,pH=4,曝气量为3 L·min-1时,一级预处理效果较好,铁碳微电解对COD去除率达47.50%,废水可生化性由0.23提升到0.38;二级预处理水解酸化将废水可生化性由0.38提升至0.46,促使MBR工艺运行效果大幅提升,最终出水达到《化学合成类制药工业水污染排放标准》(GB 21904-2008)。     

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.     

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.     

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.     

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.     

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.     

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.     

Observations on the influence of water and soil pH on the persistence of insecticides

Abstract

The pH‐disappearance rate profiles were determined at ca. 25°C for 24 insecticides at 4 or 5 pH values over the range 4.5 to 8.0 in sterile phosphate buffers prepared in water‐ethanol (99: 1 v/v). Half‐lives measured at pH 8 were generally smaller than at lower pH values. Changes in half lives between pH 8.0 and 4.5 were largest (>1000x) for the aryl carbamates, carbofuran and carbaryl, the oxime carbamate, oxamyl, and the organophosphorus insecticide, trichlorfon. In contrast, half lives of phorate, terbufos, heptachlor, fensulfothion and aldicarb were affected only slightly by pH changes. Under the experimental conditions described half lives at pH8 varied from 1–2 days for trichlorfon and oxamyl to >1 year for fensulfothion and cyper‐methrin. Insecticide persistence on alumina (acid, neutral and basic), mineral soils amended with aluminum sulfate or calcium hydroxide to different pH values and four natural soils of different pH was examined. No correlation was observed between the measured pH of these solids and the rate of disappearance of selected insecticides applied to them. These observations demonstrate the difficulty of extrapolating the pH dependent disappearance behaviour observed in homogeneous solution to partially solid heterogeneous systems such as soil.     

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.     

Radionuclides in pinon pine (Pinus edulis) nuts from los alamos national laboratory lands and the dose from consumption

Abstract

One of the dominant tree species growing within and around the eastern portion of Los Alamos National Laboratory (LANL), Los Alamos, NM, lands is the pinon pine (Pinus edulis). Pinon pine is used for firewood, fence posts, and building materials and is a source of nuts for food—the seeds are consumed by a wide variety of animals and are also gathered by people in the area and eaten raw or roasted. This study investigated the (1) concentration of ³H, ¹³⁷Cs, ⁹⁰Sr, ^totU, ²³⁸Pu, ^{239, 240}Pu, and²⁴¹ Am in soils (0‐ to 12‐in. [31 cm] depth underneath the tree), pinon pine shoots (PPS), and pinon pine nuts (PPN) collected from LANL lands and regional background (BG) locations, (2) committed effective dose equivalent (CEDE) from the ingestion of nuts, and (3) soil to PPS to PPN concentration ratios (CRs). Most radionuclides, with the exception of ³H in soils, were not significantly higher (p < 0.10) in soils, PPS, and PPN collected from LANL as compared to BG locations, and concentrations of most radionuclides in PPN from LANL have decreased over time. The maximum net CEDE (the CEDE plus two sigma minus BG) at the most conservative ingestion rate (10 lb [4.5 kg]) was 0.0018 mrem (0.018 μSv); this is far below the International Commission on Radiological Protection (all pathway) permissible dose limit of 100 mrem (1000 μSv). Soil‐to‐nut CRs for most radionuclides were within the range of default values in the literature for common fruits and vegetables.     

Degradation and sorption of imidacloprid in dissimilar surface and subsurface soils

Degradation and sorption/desorption are important processes affecting the leaching of pesticides through soil. This research characterized the degradation and sorption of imidacloprid (1-[(6-chloro-3-pyridinyl)-methyl]-N-nitro-2-imidazolidinimine) in Drummer (silty clay loam) and Exeter (sandy loam) surface soils and their corresponding subsurface soils using sequential extraction methods over 400 days. By the end of the incubation, approximately 55% of imidacloprid applied at a rate of 1.0 mg kg^?1 degraded in the Exeter sandy loam surface and subsurface soils, compared to 40% of applied imidacloprid within 300 days in Drummer surface and subsurface soils. At the 0.1 mg kg^?1 application rate, dissipation was slower for all four soils. Water-extractable imidacloprid in Exeter surface soil decreased from 98% of applied at day 1 to > 70% of the imidacloprid remaining after 400 d, as compared to 55% in the Drummer surface soil at day 1 and 12% at day 400. These data suggest that imidacloprid was bioavailable to degrading soil microorganisms and sorption/desorption was not the limiting factor for biodegradation. In subsurface soils > 40% of ¹⁴C-benzoic acid was mineralized over 21 days, demonstrating an active microbial community. In contrast, cumulative ¹⁴CO₂ was less than 1.5% of applied ¹⁴C-imidacloprid in all soils over 400 d. Qualitative differences in the microbial communities appear to limit the degradation of imidacloprid in the subsurface soils.