Fe/AC內电解-H_2O_2联合技术降解浮选废水中苯胺黑药

研究了Fe/AC內电解-H_2O_2联合技术在降解浮选废水中浮选药剂苯胺黑药(DDA)的效果及可行性。通过正交和单因素实验,考察了其工艺条件参数对DDA和COD处理效果的影响。结果表明,在初始p H=3,Fe/AC质量比为2∶1,H_2O_2投加量为0.6 mmol·L-1,Fe/AC IME和Fenton氧化工段HRT分别为60 min和20 min的条件下,模拟废水DDA和COD浓度由200 mg·L-1、395 mg·L-1分别降至28.7 mg·L-1和32.9 mg·L-1,去除率分别高达85.6%和91.7%。Fe/AC IME-H_2O_2连续处理实际浮选废水(COD 880~910 mg·L-1)96 h后,COD去除率仍维持在88.0%以上,残留浓度低于《污水综合排放标准》(GB 8978-1996)二级标准值。     

Mn_3O_4催化臭氧化钻井废水的作用机理

通过静态实验,探讨了Mn3O4对钻井废水臭氧化过程的催化作用机理,考察了Mn3O4及Cl-对臭氧分解、水体湍动程度、羟基自由基抑制剂碳酸氢根和叔丁醇的加入对COD去除率的影响,分析了反应过程中TOC和p H的变化。结果表明,催化剂加量为100 mg/L时,臭氧分解率由单独臭氧时的38.2%增加到81.4%,Mn3O4对钻井废水中有机物的吸附去除率仅为2%,O3/活性炭体系对COD去除率与单独臭氧效果接近,说明臭氧在催化剂表面存在吸附作用,促进臭氧分解;水体不搅拌与搅拌速度增加为900 r/min时,COD去除率由52%增加到58%,搅拌程度对钻井废水COD去除效果影响不大;HCO-3浓度为100 mg/L时,COD去除率降低到41.2%,说明了体系中有羟基自由基产生;氯离子浓度为1 000 mg/L,臭氧的分解率降低了9.2%,证明了臭氧在催化剂表面的吸附作用;羟基自由基抑制剂叔丁醇的加入,使得COD去除率由54.3%降低为40.8%,证实了反应体系中存在羟基自由基。同时在反应过程中,体系的TOC由191.9 mg/L降低至37.6mg/L;p H由原来的11.2降低到6.3。实验现象说明,臭氧吸附在Mn3O4催化剂表面,分解产生羟基自由基,进而氧化去除钻井废水中有机物,这在某种程度上证明了Mn3O4催化臭氧化对有机物的降解遵循羟基自由基机理。     

RPB-O3/H2O2法处理硝基苯模拟废水

在超重力场中,研究了硝基苯模拟废水的臭氧/双氧水(O3/H2O2)法处理效果,考察了超重力因子β、H2O2浓度、初始p H、液体流量及处理时间等因素对硝基苯去除率的影响。结果表明,硝基苯去除率随超重力因子β和处理时间的增加而增大,而随H2O2浓度、初始p H和液体流量的增加呈先增大后降低的趋势。当硝基苯初始浓度300 mg/L,工艺条件β=80、p H=10.0、臭氧质量浓度约为40 mg/L、H2O2浓度为4.9 mmol/L、液体流量为120 L/h时,循环处理35 min硝基苯去除率可达96.7%。处理时间60 min后,废水中硝基苯含量1.4 mg/L,COD为39 mg/L,达国家一级排放标准(GB 8978-1996)。在此条件下,硝基苯的降解过程符合准一级反应动力学。     

非均相催化臭氧氧化深度处理炼油废水

采用非均相催化剂催化臭氧氧化处理炼油废水,考察了催化剂负载率、p H、催化剂投加量和臭氧投加量及反应时间对处理效果的影响。结果表明,组合工艺最佳工艺条件为:催化剂负载率2.1%、p H 9、催化剂投量80 g/L、臭氧投量8.1 mg/L、反应时间60 min,COD、石油类、NH3-N、硫化物和SS去除率分别为91.3%、92.7%、80.5%、34.5%和59%。处理炼油废水过程中组合工艺存在明显协同效应,协同因子为1.47。中间臭氧氧化和催化臭氧氧化在最优工艺条件下对炼油废水COD的降解均符合准一级动力学规律。基于叔丁醇的实验结果,结合降解动力学可以推测,降解炼油废水过程中非均相催化剂催化臭氧产生高活性羟基自由基是降解效率提高的主导因素。     

臭氧-BAF组合工艺处理电镀RO浓水

电镀废水反渗透(RO)浓水具有盐度高、难降解有机物浓度高、含重金属等特点,是电镀废水处理工艺提标改造的难点。采用臭氧-曝气生物滤池(BAF)组合工艺,对电镀废水反渗透(RO)浓水中有机物进行处理,使出水COD浓度达到《电镀污染物排放标准》中标准。考察了废水初始p H、臭氧浓度和反应时间等因素对臭氧氧化效果的影响,以及水力停留时间(HRT)和气水比对BAF单元COD去除效果的影响。经优化后的系统运行工况为:臭氧氧化单元中废水初始p H值为10.0,臭氧浓度为31.96 mg·L~(-1),反应时间为40 min;BAF的HRT为3 h,气水比为5∶1。在最佳工况下,当进水COD为180~240 mg·L~(-1)时,经组合工艺处理后COD去除率达78.6%,平均出水COD浓度为47 mg·L~(-1),达到了标准的要求。     

响应面法优化光催化/臭氧氧化深度处理炼油废水

利用响应面方法(RSM)对光催化/臭氧氧化深度处理炼油废水工艺进行优化,考察了臭氧通量、光催化剂投加量、初始p H和反应时间对于处理效果的影响,提出采用该工艺的数学模型及优化后的工艺参数。结果表明,各影响因子对COD去除率影响顺序为反应时间>光催化剂投加量>初始p H>臭氧通量,方程的F值为11.54,相关系数为0.9537,调整相关系数为0.915,说明数学模型可以较好地模拟真实的反应曲面。优化得到最佳的工艺参数:臭氧通量1.05 L/min、光催化剂投加量0.33 g/L、初始p H 7.51、反应时间96.95 min,在该条件下,对COD去除率为97.88%,与预测值99.49%接近。采用95%处理水和5%新鲜水混合,水质达到了循环冷凝水的补充水水质指标要求。     

镀镍漂洗废水中有机物的臭氧氧化处理研究

用臭氧氧化处理镀镍漂洗废水中的有机物,主要考察pH、臭氧投加量、废水初始COD浓度、温度等因素对处理效果的影响,并对反应机理进行初步的探讨.实验结果表明,废水的COD去除率随pH的增大而升高,比较适宜的pH为6～7;适当地增加臭氧投加量有利于提高COD去除率;在一定温度范围(15～35℃)内,提高反应温度有利于废水中有机物的降解;当臭氧投加量为20 mg/(min·L),对于初始COD为56 mg/L、pH 6.5的实际镀镍漂洗废水,在25 ℃的条件下氧化100min,出水COD降至10mg/L,COD去除率达到82%;在臭氧氧化镀镍漂洗废水的反应中,部分有机物的降解是在Ni2 的催化下由臭氧分解生成氧化能力更强的自由基来完成.臭氧氧化可作为镀镍漂洗废水处理回用的预处理工艺.     

Fenton-混凝法处理苯胺废水

农药生产过程中产生的苯胺废水,COD浓度高、生物毒性强、可生化性差,一般生化方法很难处理。研究了Fenton与PAC联用处理苯胺废水。结果表明,Fenton氧化处理苯胺废水在最佳条件为pH=6、m（H2O2）/m（COD）=1.8、n（H2O2）/n（Fe2＋）=8时,COD和色度去除率分别为78.4%和92.3%。Fenton氧化后废水B/C值由0.037提高到0.324。最佳条件下联用PAC,在投加量为320 mg/L时COD与色度去除率分别为83.6%和94.8%,并且处理时间显著缩短,实际应用中可减少水力停留时间和构筑物体积。     

厌氧共代谢条件下苯胺黑药的生物降解

采用自制厌氧反应器进行不同基质与苯胺黑药的共代谢特性研究。结果表明,经过72 d的驯化,反应器启动完成。在不同基质种类和比例条件下,蔗糖、乙酸钠、葡萄糖、淀粉和维生素C对苯胺黑药的厌氧降解有促进作用。当乙酸钠与苯胺黑药的质量比为2∶1时降解效率最高,出水苯胺黑药浓度23.21 mg·L~(-1),降解率82.00%,出水COD为35.6 mg·L~(-1),去除率92.90%。对外加基质与苯胺黑药质量比为2∶1时的实验数据进行动力学分析,发现无外加基质组和共代谢基质为葡萄糖、蔗糖、淀粉和乙酸钠时,苯胺黑药的降解过程均符合一级动力学规律,而维生素C并不符合。反应速率常数的顺序为乙酸钠淀粉葡萄糖蔗糖空白。     

臭氧联合混凝沉淀法去除浮选废水中有机磷

采用臭氧-混凝沉淀法去除广西某铅锌矿选矿厂尾矿库外排废水中的有机磷。有机磷主要来源于废水中残留的巯基磷酸盐类浮选药剂苯胺黑药(二苯胺基二硫代磷酸)和丁铵黑药(二丁基二硫代磷酸铵)。实验研究表明:废水中磷的存在形式90%以上为有机磷,钙盐、铁盐和铝盐无法通过混凝沉淀将有机磷去除。研究了臭氧氧化时有机磷转化为无机磷的规律,臭氧氧化可将大部分有机磷转化为无机磷。转化后的无机磷可通过硫酸铝和PAM混凝沉淀去除,尾矿库外排废水中总磷(TP)浓度由1.4~1.7下降至0.2~0.4 mg·L~(-1),明显低于《铅、锌工业污染物排放标准》(GB 25466-2010)中的≤1.0 mg·L~(-1)的要求。     

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.