微电场-零价铁强化厌氧水解酸化性能

通过投加零价铁和增加微电场提高水解酸化的效果,改善混合工业废水的可生化性。实验在4个反应器中同步进行：微电场-零价铁厌氧反应器（R1）、微电场厌氧反应器（R2）、零价铁厌氧反应器（R3）及普通厌氧反应器（R4）。结果表明,微电场-零价铁对水解酸化具有明显的促进作用,在水力停留时间（HRT）为81 h时,TOC去除率达70%,BOD5/COD由0.15增至0.41,废水的可生化性显著提高。     

微电场-零价铁-UBF提高有机硫对位酯生产废水同步产甲烷反硝化效能

有机硫化合物对位酯生产废水具有COD高、含硫酸盐和有机硫高以及碳硫比低的特点,针对单一厌氧反应器在处理废水时只能在较低COD容积负荷(OLR)下运行的问题,在提高有机硫对位脂生产废水产甲烷反硝化效能的基础上,采用微电场-零价铁联合方式处理该类废水。实验结果表明:OLR(以COD计)为6.67 g·(L·d)-1,进水COD为20 000 mg·L-1时,复合床的COD去除率为70%,产甲烷率为1.41 L·(L·d)-1,反硝化率为87%,对位脂降解率为74%;在COD/TSO24-(总硫酸盐)为1.57时,COD去除率、产甲烷率和反硝化率可分别能稳定在60%、 1.18 L·(L·d)-1和79%;在COD/TSO24-为0.88时,产甲烷菌受到中等程度的抑制;当COD/TSO24-恢复为1.57时,厌氧系统在7 d后恢复,说明联合系统有很强的恢复能力。综合上述结果,与单一的UBF处理相比,采用微电场-零价铁能显著提高UBF的运行负荷和同步产甲烷反硝化能力,同时也能使反应器承受更低的碳硫比。     

厌氧法处理木薯淀粉废水的研究

采用厌氧法处理木薯淀粉废水,研究了厌氧反应器启动和运行的特性,以及温度和搅拌对厌氧生物降解的影响。结果表明:(1)COD去除率总体随着进水COD的增大而增大,在进水COD为9 983.38mg/L时,COD去除率最大,达到86.05%。(2)累计产甲烷量与进水COD呈正比关系,进水COD直接影响反应器的产甲烷量。(3)厌氧颗粒污泥活性最高的温度为30～35℃。(4)厌氧搅拌有利于提高厌氧颗粒污泥的产甲烷活性。     

零价铁强化城市污泥与垃圾焚烧厂渗滤液协同厌氧消化

针对城市污泥(初沉污泥、剩余污泥)和垃圾焚烧厂渗滤液2种市政废物的协同厌氧消化产气量不足的问题,采用投加零价铁的方式,探究零价铁对厌氧消化过程中产酸和产甲烷阶段的强化作用,并研究消化前后COD、VSS、氨氮以及上清液离子的变化。以初沉污泥与剩余污泥体积比4∶1、渗滤液添加量为15%的基质作为底物,投加不同浓度零价铁进行厌氧消化。结果表明：零价铁能有效提升协同厌氧消化系统中总挥发性脂肪酸产量、促进丙酸分解、进一步降解复杂有机物;当零价铁投入量为4 g·L⁻¹时,累计产甲烷量最高达189.65 mL·g⁻¹(以VSS计),相比对照组提升了30.1%,其产气速率符合一次函数和Scholl Canyon模型指数衰减规律;在25 g·L⁻¹和40 g·L⁻¹的高投加量零价铁条件下,产气高峰提前,但累计甲烷产量低于对照组;随着零价铁的投加量增加,COD降解率呈下降趋势,VSS降解率提升,氨氮变化不大;此外,消化液上清液中,正磷酸盐、硫酸根浓度明显减少,这与亚铁离子的混凝沉淀作用相关,同时也是削弱零价铁强化作用的原因之一。研究结果可为城市污泥和垃圾焚烧厂渗滤液协同厌氧消化提供参考。     

铁炭微电解强化水解酸化反应器高效处理聚乙烯醇废水

以聚乙烯醇(PVA)退浆废水为研究对象,构建了铁炭微电解强化厌氧生物处理的废水处理系统,对比研究了不同负荷条件下常规水解酸化反应器(R1,无铁炭材料)和铁炭耦合厌氧水解酸化反应器(R2,有铁炭材料)对PVA退浆废水的去除效果、颗粒污泥特性(胞外聚合物(EPS))、挥发性脂肪酸(VFAs)组成及微生物群落结构的差异。结果表明：R2出水平均COD去除率和平均PVA去除率分别稳定在86.8%和75.8%,均优于R1;添加铁炭材料可促进丙酸、丁酸转化成乙酸,提高了乙酸产量;R2颗粒污泥紧密黏附EPS(TB-EPS)、松散附着EPS(LB-EPS)含量较R1有所增加,颗粒污泥结构得到优化。高通量测序结果表明,添加铁炭对水解酸化菌群有显著影响,Propionibacteriaceae、Clostridium sensu stricto 12在PVA的降解中起重要作用。综合上述结果,铁炭微电解可有效强化水解酸化反应器对PVA退浆废水的处理效果,研究结果可为厌氧生物法处理PVA退浆废水提供参考。     

零价铁强化上流式厌氧污泥床反应器处理煤化工费托合成废水研究

采用零价铁强化上流式厌氧污泥床反应器(UASB)处理费托合成废水。结果表明:经过120d运行,在进水COD平均质量浓度30 000mg/L、HRT=4.0d、进水pH=6.5的情况下,出水COD去除率平均值最高可达到81.1%,比空白组提高了20.2百分点。同时,通过对厌氧污泥胞外聚合物(EPS)三维荧光和污泥傅立叶红外光谱分析表明,零价铁的投加显著提升了EPS中蛋白质类物质的含量,提高了厌氧微生物的代谢活性。     

有机负荷冲击对固定床厌氧反应器启动及古菌群落动态影响

为开发高效率、抗冲击能力强的有机废水沼气发酵技术,以人工配制的糖蜜废水为试材,在不同有机负荷(1.7~6.73 kg/(m3·d))的冲击方式下,对4个炭纤维膜为载体固定床厌氧反应器的启动进行了研究。通过COD去除率、p H、产气量、甲烷含量、变性梯度凝胶电泳(DGGE)、16S r DNA克隆文库技术、实时荧光定量PCR(Q-PCR)等指标和方法,分析炭纤维载体在抵御有机负荷冲击过程中的作用及对微生物定殖的贡献。结果表明,在不同有机负荷冲击下,4个炭纤维载体固定床厌氧反应器在第40天时均启动成功,其产气量稳定在21 L左右,出水p H在6.8~7.5之间,COD去除率在80%以上,甲烷含量在75%以上,其中冲击最大的R2反应器(COD每隔5 d增加5 000 mg/L)的有机负荷是固定床厌氧反应器的一个阈值。附着在炭纤维载体上的产甲烷古菌的多样性丰富,并且繁殖缓慢、容易附着的产甲烷微菌(MMB)的16S rRNA基因浓度最高,反应器中占优势的产甲烷菌是甲烷鬃毛菌(MST)和产甲烷微菌(MMB),说明炭纤维载体对微生物的定殖起到非常重要的作用,提高了污泥活性,从而提高了反应器的性能。     

金属离子对有机垃圾两相厌氧系统中UASB处理效果的促进作用

在"水解溶出 UASB反应器"处理城镇有机垃圾的两相厌氧系统中,向UASB反应器进水中添加K、Mg、Fe、Co、Ni 5种金属离子的组合促进剂,通过对UASB反应器容积负荷、产气量、产甲烷量在添加组合促进剂前后的比较,研究了组合促进剂(K、Mg、Fe、Co、Ni)对有机垃圾浸出液厌氧消化过程的促进作用.试验结果表明,添加组合促进剂后,反应器的平均容积负荷从12.89 kg COD/m3·d提高到17.79 kg COD/m3·d;平均污泥负荷从0.82 kg COD/kg VSS·d提高到1.07 kg COD/kg VSS·d.此外,平均每千克COD产气量为392.5 L,比添加组合促进剂之前增大了6.4%;而平均每千克COD产甲烷量为297.5 L,比添加组合促进剂之前增大了10.5%.对于氨氮、挥发性脂肪酸(VFA)、pH及碱度来说,在添加组合促进剂之后则无大的变化.     

ANAMMOX与反硝化协同作用及氮素负荷研究

向成功启动并稳定运行630 d后的UASB生物膜反应器系统连续添加有机物,分析其对厌氧氨氧化反应脱氮效果的影响,并进行氮素浓度负荷试验.在厌氧氨氧化反应器系统中连续投加有机COD(葡萄糖),系统运行稳定,有机COD(葡萄糖)存在对系统去除氮素能力影响不大,有机COD去除率达到92.0%,仅用23 d,在同一反应器系统中成功实现了厌氧氨氧化与反硝化协同作用脱氮.氮素浓度负荷试验阶段,进水氨氮(NH 4-N)、亚硝氮(NO-2-N)以及总氮(TN)浓度负荷分别从0.063 kg/(m3·d)和0.063 kg/(m3·d)和0.126 kg/(m3·d)提升到了0.239 kg/(m3·d)、0.315 kg/(m3·d)和0.554 kg/(m3·d),相应去除率分别为84.0%、93.0%和85.0%,厌氧氨氧化工艺的UASB生物膜反应器对氮素浓度负荷仍有很大提升空间.     

厌氧折流板反应器处理低浓度废水的运行特性研究

接种厌氧絮状污泥,采用厌氧折流板反应器在中温下进行了处理低浓度废水的试验研究.结果表明,厌氧折流板反应器有效去除了废水中的有机物,平均去除率稳定在80%以上;启动迅速,在35 d内完成,启动性能较EGSB优;水力负荷起着重要的作用;在提高负荷阶段的初期,反应器COD去除率有较大波动,随着负荷的加大,这一现象逐渐消失;在容积负荷小于2.15 kg COD/m3·d时,进水容积负荷与基质去除负荷率之间具有明显的线性正比关系;反应器的前面隔室对有机物的去除起到主要作用;在长期运行的处理低浓度废水的ABR反应器中存在产酸相和产甲烷相的自然分离现象.     

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.     

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.     

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.     

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.