厌氧膜生物反应器处理酒厂废水运行特性研究

在一体式平板厌氧膜生物反应器处理酒厂废水的试验中,研究了污染物的去除效果和平板膜组件的运行、污染情况.试验结果表明,COD容积负荷为3～7 kg/(m3·d)、水力停留时间(HRT)为16 h时,平均COD去除率达94.2%;在膜通量为4.6 L/(m2·h)、上升流速为2.5 m/h的条件下,平板膜组件能够连续运行18～20 d;在该试验中临界通量和临界上升流速分别为10～15 L/(m2·h)和5.0m/h,平板膜组件应该在这两个临界值之下运行.膜过滤阻力分析测试结果表明,泥饼层阻力是总阻力的最大组成部分.     

人工湿地植物泌氧与污染物降解耗氧关系研究

实验采用静态水培方法研究了香蒲(Typha orientalis)、芦苇(Phragmites australis)和水葱(Scirpus validus)3种常见湿地水生植物潜在泌氧能力、去污效果,并对水生植物泌氧量与污染物降解耗氧量进行了计算分析,从而阐明湿地植物泌氧与污染物降解耗氧之间的关系。结果表明,3种植物泌氧能力由大到小依次为:芦苇香蒲水葱,其中,芦苇比放氧速率、面积泌氧率均最高,分别为3.36 mg O2/(g.d)和4.35 g O2/(m2.d)。植物对湿地系统中污染物的去除有重要影响,各植物系统COD去除速率在3.46~3.77 g/(m2.d)之间;NH4+-N去除速率在0.07~0.13 g/(m2.d);TN去除速率在0.25~0.27 g/(m2.d);TP去除速率均为0.09 g/(m2.d);均好于无植物空白系统。计算表明,各植物体系泌氧量在0.48~0.55 g O2/d之间;各植物体系COD、NH4+-N耗氧量在0.41~0.46 g O2/d之间;植物净泌氧量在0.02~0.12 g O2/d之间。植物泌氧量与COD、NH4+-N耗氧量呈显著正相关关系。若应用人工湿地处理城镇生活污水,各植物体系COD最大去除负荷在3.81~4.35 g/(m2.d)之间,NH4+-N最大去除负荷在0.83~0.95 g/(m2.d)之间,最大水力负荷在1.65~1.89 cm/d之间。     

曝气生物滤池去除有机物及硝化氨氮的影响因素研究

采用以陶粒为填料的曝气生物滤池(BAF)处理低浓度生活污水,研究在气水比一定的条件下,水力负荷、有机负荷及氨氮负荷对BAF去除有机物及硝化氨氮的性能的影响.研究结果表明,当试验进水COD为105.8～156.6 mg/L,气水比为3:1的条件下,降解有机物的最佳水力负荷为1.35～1.68 m3/(m2·h),COD平均去除率为86.3%.氨氮负荷是影响反应器硝化性能的直接因素.当水力负荷为1.05 m3/(m2·h),平均进水COD为106.1 mg/L时,若使出水氨氮低于15 mg/L,则反应器能承受的最大进水氨氮负荷为0.5 kg/(m3·d)左右.并确立了相应的反应器动力学模型.     

海南火山岩滤料曝气生物滤池工艺优化研究

本研究基于上向流曝气生物滤池污水处理系统,研究了该工艺不同气水比、不同水力停留时间、不同滤料高度层、反冲洗强度对污染物的处理效能的影响。结果表明,气水比为4∶1、水力停留时间2 h时,BAF出水中COD、NH+4-N和SS指标达到最佳;沿程污染物去除率随着滤料层高度的增加逐渐增大,当滤料高度大于1.6 m时趋于稳定,COD、NH+4-N和SS平均去除率分别达到80%、99%和80.3%。建议曝气生物滤池的反冲洗推荐程序为:先气冲(18 L/(m2·s)),单独气洗2~3 min;再气冲(18 L/(m2·s))加水冲(5 L/(m2·s)),联合反冲洗3~5 min;最后水冲(5 L/(m2·s)),漂洗5~8 min。     

生态透水带去除洱海流域生活污水氮的效果

洱海流域部分村镇生活污水缺乏系统收集及管理而直排,对洱海水质造成了显著不利影响。通过构建生态透水带,旨在摸清其去除分散式生活污水中氮的能力、机理、植物种类对除氮的影响及透水带最佳宽度。构建了4条规格为4 m×1 m×0.5 m的生态透水带,均匀敷设厚0.3 m,粒径10~18 mm(平均14 mm)的碎石。其中3条分别种植本地植被芦苇、水葱和香蒲,余下1条为空白带。实验周期3个月,每星期采水样1次,持续进水,水量0.3 m3·d~(-1),水力负荷7.5cm·d~(-1),进水总氮(TN)平均浓度31.15 mg·L~(-1)。结果表明,透水带具有很好的除氮效果,TN去除率依次为:香蒲(80.22%)水葱(76.98%)芦苇(69.23%)空白(63.61%),植物类型对透水带TN去除效果影响显著(P0.05)。平均TN出水浓度依次为:香蒲(6.16 mg·L~(-1))、水葱(7.17 mg·L~(-1))、芦苇(9.58 mg·L~(-1))、空白(11.34 mg·L~(-1)),均达到了城镇污水处理厂污染物排放标准的一级A标准。平均氨氮出水浓度依次为:香蒲(4.47 mg·L~(-1))、水葱(5.48mg·L~(-1))、芦苇(8.23 mg·L~(-1))、空白(9.67 mg·L~(-1)),种植植物的条带达到了城镇污水处理厂污染物排放标准的一级B标准。在TN去除率为80%时,不同透水带最佳宽度不同,香蒲(3.9 m)水葱(4.7 m)芦苇(6.3 m)空白(8.6 m)。     

A/O一体化曝气生物滤池降解酱油废水的研究

针对组分复杂、色度较高的酱油废水,采用A/O一体化曝气生物滤池进行处理,研究了该反应器处理酱油废水的运行参数及降解动力学.结果表明:采用以废弃物煤渣为主的混合填料,能有效去除废水中的有机物和色度.当水力负荷为1.12 m3/(m2·h),容积负荷为0.15～0.43 kg COD/(m3·d)的条件下,反应器的COD去除率能维持在75%～85%之间,色度去除率均在80%以上,最高达到了93.3%;当容积负荷小于0.27 kg COD/(m3·d)时,出水的各项指标能达到(GB8978-1996)的一级排放标准.根据试验结果,反应器O段的降解动力学可表达为Se/S0=exp(-1.0125H).     

3种浮床植物系统对富营养化水体净化效果研究

研究了风车草(Cyperus alternifolius)、菖蒲(Acorus calamus)和富贵竹(Dracaena sanderiana)3种浮床植物系统对富营养化水体净化效果,试验共持续35 d。结果表明,在水温24～30℃条件下,风车草和菖蒲生长良好,生物量大,而富贵竹生长较差,生物量增加少;3种植物对NH_4~+-N的去除率分别为76.8%、85.5%和53.6%,对TN的去除率分别为69.1%、66.2%和54.4%,对TP的去除率分别为76.9%、84.6%和61.5%,对PO_4~(3-)-的去除率分别为91.7%、91.7%和75%,对真实色度有明显的去除效果;3种植物对氮磷和真实色度去除效果与对照之间均达到显著差异(P0.05),自然沉淀是浊度去除的主要原因,植物吸收同化作用是NH_4~+-N去除的主要途径,植物吸收是溶解性磷去除的主要途径。试验表明,风车草和菖蒲对富营养化水体中氮磷和真实色度有较好的去除效果,可作为富营养化水体治理的优良物种而推广使用。     

生物转鼓过滤器反硝化净化NO的效率研究

采用自行研制的生物转鼓过滤器(RDB)反硝化净化NO。结果表明,在实验温度为25～30℃、pH为7.0～7.5、转鼓转速为1.0r/min、空床停留时间(EBRT)为86.40s、营养液用量为5.0L、营养液更换频率为0.2L/d的条件下,RDB在30d内完成挂膜;RDB稳定运行期间,当NO进气质量浓度为90～433mg/m3时,NO去除率维持在42.9%～85.2%,平均去除负荷为10.40g/(m3.h);转鼓转速决定了生物膜表面的更新速率和液膜厚度,当转速为0.5r/min时,NO去除率达到最大值(75.0%);将营养液用量控制在1.3～3.0L较为合理;EBRT是决定反硝化效率的重要因素,当EBRT为345.60s时,NO去除率不受其进气浓度的影响,且去除率高达95%以上,当EBRT为43.20s、NO进气质量浓度从98mg/m3增加到1095mg/m3时,NO去除率从62.5%下降到30.7%,当进气负荷为50.00g/(m3.h)时,NO去除负荷达到最大值(27.50g/(m3.h))。     

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.     

生物滴滤塔净化甲苯启动性能研究

研究以甲苯为驯导物的生物滴滤塔挂膜启动阶段净化性能的变化。实验结果表明,通过控制pH和湿度得到了真菌滴滤系统,启动周期为14 d,比细菌滴滤塔长7 d;在进化性能方面,在入口负荷、浓度为80 g/(m3.h)、3 000 mg/m3的条件下获得了稳定在98%以上的去除效率;对比2种填料对启动阶段的影响,在较低负荷下(≤80 g/(m3.h))对系统的启动时间和去除效率没有显著影响。     

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.     

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.     

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.     

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.     

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.     

Biochemical interaction of six op delayed neurotoxicants with several neurotargets

Abstract

Five organophosphorous insecticides: Leptophos, EPN, Cyano‐fenphos, trichloronate and salithion proved to cause irreversible ataxia not only to chicken but also to mice and sheep. TOCP was included as a reference. Cyanofenphos blocked the catecholamine B‐receptor binding activity with ³H‐norepinephrine at a level similar to that of the specific inhibitor propranolol in the mouse heart preparation. In the lamb heart preparation, the B‐receptor was more sensitive to Leptophos, salithion and TOCP than to propranolol. The six compounds and their oxons were screened for their in‐vitro inhibition to monamine oxidase (MAO), acetyl cholinesterase (AChE) and neurotoxic esterase (NTE) in the brain of either mouse, lamb or chicken. It is believed that their AChE inhibition stands for their acute toxicity, while NTE inhibition is responsible for their paralytic ataxia.     

Phytoextraction of lead-contaminated soil using vetivergrass (<Emphasis Type="Italic">Vetiveria zizanioides</Emphasis> L.), cogongrass (<Emphasis Type="Italic">Imperata cylindrica</Emphasis> L.) and carabaograss (<Emphasis Type="Italic">Paspalum conjugatum</Emphasis> L.)

Background, Aims and Scope The global problem concerning contamination of the environment as a consequence of human activities is increasing. Most of the environmental contaminants are chemical by-products and heavy metals such as lead (Pb). Lead released into the environment makes its way into the air, soil and water. Lead contributes to a variety of health effects such as decline in mental, cognitive and physical health of the individual. An alternative way of reducing Pb concentration from the soil is through phytoremediation. Phytoremediation is an alternative method that uses plants to clean up a contaminated area. The objectives of this study were: (1) to determine the survival rate and vegetative characteristics of three grass species such as vetivergrass, cogongrass and carabaograss grown in soils with different Pb levels; and (2) to determine and compare the ability of the three grass species as potential phytoremediators in terms of Pb accumulation by plants. Methods The three test plants: vetivergrass (Vetiveria zizanioides L.); cogongrass (Imperata cylindrica L.); and carabaograss (Paspalum conjugatum L.) were grown in individual plastic bags containing soils with 75 mg kg⁻¹ (37.5 kg ha⁻¹) and 150 mg kg⁻¹ (75 kg ha⁻¹) of Pb, respectively. The Pb contents of the test plants and the soil were analyzed before and after experimental treatments using an atomic absorption spectrophotometer. This study was laid out following a 3 × 2 factorial experiment in a completely randomized design. Results On the vegetative characteristics of the test plants, vetivergrass registered the highest whole plant dry matter weight (33.85–39.39 Mg ha⁻¹). Carabaograss had the lowest herbage mass production of 4.12 Mg ha⁻¹ and 5.72 Mg ha⁻¹ from soils added with 75 and 150 mg Pb kg⁻¹, respectively. Vetivergrass also had the highest percent plant survival which meant it best tolerated the Pb contamination in soils. Vetivergrass registered the highest rate of Pb absorption (10.16 ± 2.81 mg kg⁻¹). This was followed by cogongrass (2.34 ± 0.52 mg kg⁻¹) and carabaograss with a mean Pb level of 0.49 ± 0.56 mg kg⁻¹. Levels of Pb among the three grasses (shoots + roots) did not vary significantly with the amount of Pb added (75 and 150 mg kg⁻¹) to the soil. Discussion Vetivergrass yielded the highest biomass; it also has the greatest amount of Pb absorbed (roots + shoots). This can be attributed to the highly extensive root system of vetivergrass with the presence of an enormous amount of root hairs. Extensive root system denotes more contact to nutrients in soils, therefore more likelihood of nutrient absorption and Pb uptake. The efficiency of plants as phytoremediators could be correlated with the plants’ total biomass. This implies that the higher the biomass, the greater the Pb uptake. Plants characteristically exhibit remarkable capacity to absorb what they need and exclude what they do not need. Some plants utilize exclusion mechanisms, where there is a reduced uptake by the roots or a restricted transport of the metals from root to shoots. Combination of high metal accumulation and high biomass production results in the most metal removal from the soil. Conclusions The present study indicated that vetivergrass possessed many beneficial characteristics to uptake Pb from contaminated soil. It was the most tolerant and could grow in soil contaminated with high Pb concentration. Cogongrass and carabaograss are also potential phytoremediators since they can absorb small amount of Pb in soils, although cogongrass is more tolerant to Pb-contaminated soil compared with carabaograss. The important implication of our findings is that vetivergrass can be used for phytoextraction on sites contaminated with high levels of heavy metals; particularly Pb. Recommendations and Perspectives High levels of Pb in localized areas are still a concern especially in urban areas with high levels of traffic, near Pb smelters, battery plants, or industrial facilities that burn fuel ending up in water and soils. The grasses used in the study, and particularly vetivergrass, can be used to phytoremediate urban soil with various contaminations by planting these grasses in lawns and public parks. ESS-Submission Editor: Dr. Willie Peijnenburg (wjgm.peijnenburg@rivm.nl)