长期运行的不同序批式活性污泥工艺去除Cr(Ⅵ)的比较研究

对不同序批式(SBR)活性污泥工艺,即厌氧SBR、好氧SBR及厌氧好氧SBR去除废水中的Cr(Ⅵ) 进行了研究。结果表明,在反应器起始Cr(Ⅵ)浓度为0.5～2 mg/L时,好氧SBR的Cr(Ⅵ) 去除率低于20％,微生物量不断降低;厌氧和厌氧好氧SBR的Cr(Ⅵ)去除率都达到94％以上,但前者的微生物量持续减少、出水浊度高,而后者的微生物量稳定增加、出水浊度低。因此,厌氧好氧SBR更适合于去除废水中的Cr(Ⅵ)。对厌氧好氧SBR系统的进一步研究表明,该系统在厌氧阶段有明显的磷释放、聚羟基烷酸(PHA)合成和糖原降解,好氧阶段有明显的磷吸收、PHA降解和糖原合成。还对厌氧好氧SBR中Cr(Ⅵ) 的去除机理进行了讨论。     

不同季节的沼液中细菌分离培养与含量分析

采用TPY琼脂分别对不同季节的好氧、厌氧沼液中的细菌进行需氧和厌氧培养,对培养出的细菌进行计数和形态观察。结果表明：（1）夏季厌氧沼液中厌氧菌及兼性细菌数量均极显著高于春季;夏季好氧沼液中好氧菌数量显著高于春季。（2）冬季厌氧沼液的厌氧培养和需氧培养的细菌数量,均极显著低于秋季;冬季好氧沼液中的需氧培养出的细菌数,显著低于秋季。（3）夏、秋季的厌氧招液,厌氧培养出的细菌数极显著高于好氧沼液厌氧培养出的细菌;冬季厌氧沼液厌氧培养出的细菌数,显著高于好氧沼液厌氧培养出的细菌。（4）沼液中的细菌种类繁多,表型特征复杂。（5）沼液中的杆菌最多,其夏季各种形状菌都较其它季节多。（6）四季沼液中,革兰氏阴性菌均占多数,革兰氏阳性菌均占少数。     

蔬菜与餐厨垃圾厌氧发酵启动阶段微生物分析简

为了研究厌氧发酵启动阶段微生物菌群结构、数量变化情况与沼气产量的关系,分别对蔬菜废弃物和餐厨垃圾单一物料发酵进行分析,并测定pH值、挥发性脂肪酸（VFA）、氧化还原电位。结果表明,餐厨垃圾比蔬菜废弃物的启动时间长,但产气持久。蔬菜废弃物中细菌达峰值的时间早于餐厨垃圾,说明蔬菜废弃物中的有机质更利于微生物降解利用。两种原料中的微生物群落结构变化一致,启动阶段初期好氧和兼性厌氧细菌属优势菌,其中产酸菌增殖速率高于氨化细菌,是启动阶段降解有机质的主要菌群。随后厌氧细菌快速增殖,日增殖速率由不足20%增长到近100%并保持稳定。厌氧纤维素降解菌在启动阶段增殖较慢,原料中纤维素降解在厌氧发酵后期。原料液VFA中丁酸含量最多,最高浓度4.7 mg/mL以上,占有机酸总量总量的46%以上,厌氧发酵类型为丁酸发酵型。     

蔬菜与餐厨垃圾厌氧发酵启动阶段微生物分析

为了研究厌氧发酵启动阶段微生物菌群结构、数量变化情况与沼气产量的关系,分别对蔬菜废弃物和餐厨垃圾单一物料发酵进行分析,并测定pH值、挥发性脂肪酸（VFA）、氧化还原电位。结果表明,餐厨垃圾比蔬菜废弃物的启动时间长,但产气持久。蔬菜废弃物中细菌达峰值的时间早于餐厨垃圾,说明蔬菜废弃物中的有机质更利于微生物降解利用。两种原料中的微生物群落结构变化一致,启动阶段初期好氧和兼性厌氧细菌属优势菌,其中产酸菌增殖速率高于氨化细菌,是启动阶段降解有机质的主要菌群。随后厌氧细菌快速增殖,13增殖速率由不足20％增长到近100％并保持稳定。厌氧纤维素降解菌在启动阶段增殖较慢,原料中纤维素降解在厌氧发酵后期。原料液VFA中丁酸含量最多,最高浓度4．7mg／mL以上,占有机酸总量总量的46％以上,厌氧发酵类型为丁酸发酵型。     

好氧颗粒污泥的形成过程、形成机理及相关研究

利用SBR和优势混合菌对造纸废水进行处理,在此过程中驯化出好氧颗粒污泥,对好氧颗粒污泥的形成过程、形成机制等进行研究发现,好氧颗粒污泥的形成经历了细菌增殖、絮状体形成、絮状体聚合、凝絮体形成和好氧颗粒污泥形成五个阶段;其形成至少有菌丝缠绕、小块污泥互相联合、吸附和连接四种机制。优势混合菌的加入,是好氧颗粒污泥之所以能够形成的关键因素。     

贫营养中药废水处理系统稳定性析因

云南某制药厂生产废水有机物浓度高、氮磷含量低(贫营养),但废水处理系统长期运行稳定,且处理效果好,COD和BOD的去除率均能达到90％以上.为揭示该贫营养污水处理系统长期高效稳定运行原因,分别从工艺运行和微生物学角度对该系统进行了全面分析.结果表明,该系统厌氧和好氧段氮磷含量低,TN、TP的质量浓度分别为9.68mg·L-1、1.17 mg.L-1和6.18 mg·L-1、0.25 mg·L-1;该系统好氧池和厌氧池中均发现了以降解有机物为主的优势菌属,好氧池比厌氧池具有更高的微生物丰富度和多样性.好氧池中主要菌属为Amaricoccus、Methylibium、Reyranella 和 Plasticicumulans4i 种.其中,丰度最高的Amaricoccus占比为8.03％,该菌属能在氮、磷营养受限的环境中增殖.厌氧池中的优势菌属为Geobacter、Paludibacter、Leptolinea和Syntrophomonas.其中,占比2.49％的Leptolinea为贫营养菌属.贫营养环境条件对微生物群落的生长施加了选择压,促进了贫营养菌的优势增长.这些优势菌在废水处理系统降解污染物的各个阶段分工合作,保障了该系统的稳定运行和良好的处理效果.     

溶解氧对晚期垃圾渗滤液短程硝化及微生物群落结构变化的影响

以上海老港垃圾填埋场配套污水处理设施中的污泥为菌种源,在序批式活性污泥反应器(SBR)中对晚期垃圾渗滤液进行短程硝化处理,调节SBR中溶解氧浓度,考察溶解氧对渗滤液短程硝化的影响,分析不同溶解氧条件下污泥微生物群落结构的变化.结果表明,低溶解氧(0.2～0.5 mg/L)条件下,SBR可以获得较高的短程硝化效率,反应17h后,SBR内亚硝态氮/氨氮(质量比)为1.05,氨氮负荷可达到1.5 kg/(kg·d)(以每千克污泥悬浮固体每天承担的氨氮计),出水可以满足后续厌氧氨氧化处理的要求.从污泥变形梯度凝胶电泳(DGGE)图谱中可以看出,SBR微生物群落结构中主要优势种有uncultured Bacteroidetes bacterium、uncultured bacterium、uncultured Candidatus Amoebophilus sp.等.随着溶解氧含量的升高,SBR内微生物群落结构的多样性有所升高,但溶解氧对微生物群落结构影响有限.     

厌氧—气浮法处理化纤印染废水的微生物学特性

在处理可生化性极差(BOD_5:COD为15～20％)的化纤印染废水的厌氧装置中,存在相当数量的各类群微生物,并呈明显的生物相分布及其菌数梯度。好氧性细菌、放线菌和霉菌的优势菌分别属于菌胶团属(Zoogloea)、诺卡氏菌属(Nocardia)和曲霉属(Aspergillus)。优势产甲烷菌为甲烷八叠球菌(Methanosarcina sp.)和甲烷丝菌(Methanothrix sp.)。位于生物膜中的厌氧细菌对氧不敏感。     

反硝化聚磷菌群的培养驯化

以污水处理厂二沉池的活性污泥为种泥,采用SBR反应器初步完成了反硝化聚磷菌（DPB）的培养与驯化.在第1阶段的30 d里,污泥进行了厌氧-好氧驯化,聚磷菌好氧吸磷最终可基本稳定在85%左右,然后转变驯化条件进行第2阶段的厌氧-缺氧驯化,60 d后磷的去除率稳定在70%左右.通过实验得出,硝酸盐的消耗量与磷的吸收量基本呈线性关系,认为系统基本完成了污泥的驯化.     

优势菌的筛选及其强化活性污泥好氧反硝化的研究

利用含活性污泥提取物的贫培养基筛选SBR系统中的好氧异养优势菌。结合自然温度（15～20℃）、延长培养时间等条件来提高菌群的可培养性。从SBR活性污泥系统中分离出5种细菌。4株去除COD优势菌,1株异养硝化细菌,能在好氧条件下实现对总氮的去除。反应池底采用边缘对称曝气,反应池内细菌在时间顺序和空间位置上循环经历好氧过程及微氧过程。将PVA铝盐法固定的细菌对反应器进行生物强化。结果显示,在好氧工艺的条件下,投加优势菌群后,与未加优势菌群的反应器相比,可以显著改善污泥的沉降性能,COD、NH₃-N和TN降解率显著提高,分别达到98%、97%和90%。生物强化作用明显,反应器内具有良好的好氧反硝化环境。     

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)