Fenton试剂法预处理发酵甘油生产提取废水

采用Fenton试剂预处理高浓度难降解发酵法甘油生产提取废水。研究了pH、Fe^2 、H2O2、反应时间和H2O2投加次数对废水COD去除效果的影响。结果表明，通过Fenton试剂氧化可使废水中的COD值从13500mg／L降至4030mg／L，COD去除率达到70．1％。废水的BOD5／COD值从0．202提高至0．568，可生化性得到较大提高，为后续处理创造了条件。研究成果为发酵法甘油生产提取废水的预处理提供了一种非常有效的方法。     

芬顿试剂预处理杀螟丹农药废水

利用芬顿试剂(Fenton)氧化预处理杀螟丹农药废水,分别考察了H2O2与Fe SO4·7H2O投加量、初始p H、反应时间、温度和摇床转速对Fenton试剂处理杀螟丹废水的影响。结果表明,杀螟丹废水初始COD为676.8 mg/L时,取废水样100 m L,优化反应条件为Fenton试剂的用量1 g Fe SO4·7H2O+4 m L H2O2,初始p H值为3,搅拌强度为160 r/min的摇床转速,反应温度25℃,反应时间60 min。在优化反应条件下COD的去除率达到83.9%。通过Fenton降解,废水可生化性BOD5/COD从0.0745~0.0747上升至0.9066~0.9228,可生化性大幅提高,为后续生化处理创造了条件。考虑到运用于工业废水处理中经济成本等实际问题,建议选取Fenton试剂的用量0.5 g Fe SO4·7H2O+1 m L H2O2,COD去除效率能达到65.5%。     

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.     

Fe2+/H2O2法处理草浆纸厂废水的影响因素研究

Fenton试剂作为一种具有强氧化性的试剂,广泛地应用于废水处理的研究中.通过正交实验对Fenton试剂处理废水的几种影响因素进行了讨论,得出了影响因素的次序:Fe2 的投加量＞H2O2的投加量＞pH值＞反应时间.同时得到Fenton试剂处理造纸废水的最佳工艺条件:pH=5.0,FeSO4·7H2O的投加量为5.93g/L,H2O2的投加量为8.8‰(体积百分比),搅拌时间0.5 h,COD值由原来的2167 mg/L降至187 mg/L,COD去除率达到91.37%.     

生化-调碱后垃圾渗滤液的Fenton深度处理效果

针对上海老港垃圾填埋场经过厌氧-曝气塘处理后的渗滤液难进一步处理的问题,对其采用厌氧滤池-好氧接触法、氧化钙2种方式预处理,在此预处理基础上,考察了Fenton法深度处理的效果,探讨了H2O2/Fe2+投加比、初始pH、H2O2投加量、反应时间和Fenton试剂投加方式对渗滤液COD去除效果的影响。研究发现:经过生物预处理后,渗滤液的COD和TP分别降低了24%和25%;氧化钙调碱可以进一步使COD和TP去除率分别达到42%和96%;后续Fenton深度氧化的最佳条件为:初始pH为2,H2O2投加量为2.4 g/L,H2O2/Fe2+摩尔比为5∶1,Fenton试剂一次投加,反应时间为2 h。在此条件下,渗滤液的COD从1 340 mg/L降到198 mg/L,总COD去除率达到85%。     

超声波/Fenton处理含酚废水的影响因素

实验研究主要影响因素对超声波/Fenton试剂处理苯酚废水效果的影响,确定工艺参数。以人工配制的模拟苯酚废水为实验水样,通过静态实验研究p H值、Fe SO4·7H2O投加量、H2O2投加量和超声时间对苯酚和COD去除率的影响。研究结果表明,对于苯酚浓度为200 mg/L,COD为476.6 mg/L苯酚废水,在实验用水量为1 000 m L,p H值为6,Fe SO4·7H2O投加量为800 mg/L,H2O2投加量为Qth,超声时间为30 min的条件下,苯酚去除率可达到92.27%,COD去除率可达到82.48%,处理后苯酚浓度为14.80 mg/L,COD为83.50 mg/L。p H值、Fe SO4·7H2O投加量、H2O2投加量和超声时间对超声/Fenton工艺处理苯酚废水均有较显著地影响,工程应用时应给予足够的重视。     

UV/Fenton法预处理橡胶促进剂生产废水

采用UV/Fenton法对橡胶促进剂废水进行预处理.当原水COD约为3000 mg/L时,COD去除率可达65%以上,并得到最佳操作条件为:H2O2投加量为8 mL/L,Fe2 投加量为0.8 g/L,反应时间为30 min,pH=5;同时得到Fenton试剂处理该废水的最佳条件为:H2O2投加量为10 mL/L,Fe2 投加量为0.966 g/L,反应时间为30 min,pH=5;单独UV作用的最佳工艺条件为:反应时间为20 min,pH=5;并就3种处理方法进行了比较,发现UV对Fenton试剂处理橡胶促进剂废水具有一定促进作用.反应前后的紫外光谱说明,经UV/Fenton或Fenton反应后原水中的苯胺、硝基苯等物质已得到了彻底的氧化分解.     

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。     

UV/Fenton法预处理橡胶促进剂生产废水

采用UV／Fenton法对橡胶促进剂废水进行预处理。当原水COD约为3000mg／L时，COD去除率可达65％以上，并得到最佳操作条件为：H2O2投加量为8mL／L，Fe^2＋投加量为0．8g／L，反应时间为30rain，pH=5；同时得到Fenton试剂处理该废水的最佳条件为：H2O2投加量为10mL／L，Fe^2＋投加量为0．966g／L，反应时间为30min，pH=5；单独UV作用的最佳工艺条件为：反应时间为20min，pH=5；并就3种处理方法进行了比较，发现UV对Fenton试剂处理橡胶促进剂废水具有一定促进作用。反应前后的紫外光谱说明，经UV／Fenton或Fenton反应后原水中的苯胺、硝基苯等物质已得到了彻底的氧化分解。     

Fenton试剂氧化预处理橡胶促进剂NS生产废水的研究

采用Fenton试剂氧化处理橡胶促进剂NS生产废水,研究H2O2、Fe2＋投加量及pH值对COD去除率的影响。通过实验,确定了Fenton试剂处理该废水的最佳操作条件：pH值为3,Fe2＋加入量为0.3 g/L,而H2O2为15 mL/L。     

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.     

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.     

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.     

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.