一体式膜生物反应器处理生活污水的中试研究

采用中试规模(1.8 m3/d)的缺氧-好氧膜生物反应器(A/O MBR)对城市污水处理回用进行了试验研究.试验结果表明,该工艺处理效果优良,系统对COD、氨氮、浊度、总氮、总磷去除率较高,COD、氨氮出水浓度分别为7～39 mg/L、0～1.31 mg/L.出水水质优于城市杂用水水质标准(GB/T18920-2002).     

混凝沉淀-SBR-活性炭过滤处理垃圾渗滤液

采用沉淀-SBR-活性炭过滤复合工艺对城市垃圾渗滤液进行处理，确定混凝、SBR和活性炭过滤的最隹参数。结果表明，当进水COD为2500mg／L、氨氮在900mg／L的条件下，经该系统处理后，出水COD均在300mg／L以下，氨氮在20mg／L以下，COD去除率达90％以上，氨氮去除率达98％以上，达到较好的去除有机物和去氨效果。     

一种新型复合球填料在低浓度污再生回用中的应用研究

新型复合球填料为沸石与悬浮球填料的有机组合体，密度约为0．92～0．97g／cm^3，比表面积为711～1185m^2/m^2，表面粗糙，物化性能稳定。在曝气量为20：1，停留时间为6h时，装有新型复合球填料的反应柱挂膜容易，成膜时间短，膜不易脱落，且生物相丰富。膜成熟时对生活污水中的氨氮和COD都有很好的去除效果，出水氨氮浓度≤2mg／L，去除率≥93％；出水COD浓度≤22mg／L，去除率≥80％。新型复合球反应柱在稳定状态处理低浓度的二级出水时，出水氨氮浓度≤2mg／L，去除率89％，出水COD浓度为10～36mg／L，去除率为48％～81％。出水水质符合GB50335-2002标准。     

水解酸化＋CAST作为盐酸金霉素生产废水二级处理的工艺设计与应用

研究采用水解酸化＋CAST工艺,对盐酸金霉素生产废水进行二级处理。试验结果表明,在进水COD质量浓度高达6000mg／L左右、氨氮质量浓度高达2200mg／L的情况下,系统出水COD浓度为350mg／L,去除率达94％以上;氨氮出水质量浓度为400mg／L,去除率达到81％,取得了较好的去除效果。     

A／O-MBR工艺处理校园生活污水中水回用工程的设计与运行

针对Et处理量为1500m3的高校中水处理设施,论述了缺氧／好氧-MBR（A／O—MBR）处理工艺运行特性,完成了长效监测及经济性评价。系统MBR池污泥浓度（MLSS）控制在8～12g／L,缺氧池和好氧池水力停留时间（HRT）分别为3h和7h,污泥回流比为200％～300％。当进水COD、总氮、氨氮平均浓度分别为481．3、75．1和65．8mg／L时,出水COD、总氮、氨氮平均浓度分别为16．5、13．4和0．7mg／L,平均去除率分别为96．4％、81．9％和99．0％。在进行化学除磷的情况下,出水总磷的平均浓度为0．8mg／L,平均去除率86．5％。出水水质优于《城市污水再生利用城市杂用水水质》（GB／T18920—2002）中的相应水质指标要求。经济性分析结果显示,该中水站的电耗为0．58kWh／m3。     

UASB反应器处理生活污水的试验研究

采用UASB中试（100m^3／d）对生活污水处理进行了研究。试验结果表明，采用此系统处理生活污水，出水水质良好。COD的去除率在52％-83％，出水的COD值〈100mg／L以下，SS的去除率在95％左右，UASB处理生活污水的最佳停留时间为6h。产气率在0．1m^3／d。不管停留时间在10h、5h，出水的氨氮、乙酸值比进水的高；钙、镁、总氮、总磷、硫酸根和硝酸根离子出水值比进水值低。     

采用HSB菌种生化处理焦化废水

采用HSB微生物菌种技术和缺氧-好氧（O-O／A工艺）组合工艺处理焦化废水的研究,结果表明,该技术处理焦化废水有很好的效果,COD从2500mg／L左右降至130mg／L以下,去除率达94．8％以上;NH3-N从500mg／L降至15mg／L以下,去除率达97％以上;出水COD、氨氮、酚、氰、油等污染物均可达《污水综合排放标准》（GB8987--1996）二级标准。     

温度对复合厌氧折流板膜生物反应器处理生活污水效能的影响

将新型CAMBR反应器（厌氧折流板反应器（ABR）与膜生物反应器（MBR）优化组合）用于处理生活污水,研究温度对该反应器处理效能的影响。实验水力停留时间7．5h,混合液回流比设置为200％,pH值为6．5～8．5,溶解氧3mg／L左右。控制3个温度梯度：高温（32～37％）,中温（20～25℃）,低温（5～10％）,每个温度运行35d。结果表明,在高温条件下,系统出水COD、NH4．N、TN和TP平均浓度分别为25、0．5、12．5和0．7mg／L。在中温条件下,系统出水COD、NH4＋-N、TN和TP浓度分别30、1．2、12．5和0．4mg／L。在低温条件下,COD和TP分别经过15d和20d调整适应,出水可恢复至35mg／L和1mg／L。由于低温（10％以下）对硝化细菌产生强烈抑制,出水NH4＋-N去除率最终稳定在35％,TN去除率为40％。低温条件下,该反应器应用于污水处理中需注意适当保温,以保证出水水质。     

天然色素生产废水的生物处理研究

天然色素生产废水是一种色度大、难处理的高浓度有机废水，为了寻找该废水的有效处理方法，本文作者采用由升流式厌氧污泥床（UASB）、生物接触氧化、混凝吸附组成的废水处理工艺，对该废水进行了处理试验，结果表明，对稀释4倍的原水，当进水COD为14900mg／L左右时，UASB经过36h的水力停留时间，COD的去除率为58．2％～60．2％、出水色度为180～270倍，SS为119～126mg／L，pH值为6．5～6．8；UASB出水经过24h好氧生物接触氧化反应，COD的去除率超过90％，SS〈70mg／L；最终经过Ca（CIO）2氧化和煤渣吸附深度处理，脱色可至无色，出水COD为200mg／L以下。UASB-生物接触氧化-氧化吸附组合处理工艺处理该类天然色素生产废水是可行的。     

竹丝生物膜法和生态床组合工艺废水处理的试验研究

研究了竹丝生物膜法和生态床组合工艺处理模拟废水,讨论了该组合工艺对模拟废水中COD、氨氮和浊度的去除效果,着重讨论了生态床处理效果的影响因子。试验结果表明,竹丝生物膜法能很好地去除COD、氨氮和浊度等,在水温为9.0～10.5℃、水力停留时间为5.0h、进水COD为98.78～222.69mg/L、氨氮为5.46～12.97mg/L、浊度为26.42～59.84NTU时,出水COD为11.53～20.38mg/L,氨氮为0.42～0.86mg/L,浊度为12.38～17.30NTU。竹丝生物膜法出水再经过简易的生态床工艺,生态床出水COD为9.59～18.84mg/L,氨氮为0.43～0.90mg/L,浊度为6.77～14.15NTU;在此过程中发现,生态床中的鱼类对浊度和COD的去除均有明显效果,而光合作用对生态床COD的去除有促进作用,但是生态床对氨氮浓度却有升高作用。     

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.     

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.     

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.     

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)