2种不同填料曝气生物滤池处理生活污水的经验模型

对分别装有火山岩和陶粒填料的2套平行运行的曝气生物滤池,在不同的进水负荷下进行生活污水的试验研究,结果表明火山岩的溶解性COD(SCOD)去除效果要优于陶粒。同时,根据大量试验数据针对2个反应器进出水SCOD随反应器高度的变化关系,建立一套经验模型。推算出不同水力负荷下的经验模型常数n和K值,结果表明模型的预测值与实测值是相吻合的,该模型可作为设计者和运行者的参考依据。     

初沉污泥球磨破解后水解酸化研究

采用球磨机对污水处理厂初沉池的污泥进行球磨破解以控制初沉污泥粒径,然后在不同条件下(污泥粒径、系统pH、污泥投配率)考察初沉污泥的水解酸化效果(以溶解性COD(SCOD)变化显示),以确定初沉污泥水解酸化的最佳条件。结果表明,初沉污泥的最佳水解酸化条件为:污泥粒径25μm、系统pH 11、污泥投配率10%、水解酸化时间5d,此时反应后系统SCOD为8 256mg/L,污泥水解转化效率为32.0%。通过球磨破解、水解酸化的方式回收初沉污泥中的碳源具有一定的可行性和较好的开发利用前景。采用球磨机作为污水处理厂初沉污泥预处理的装置,与其他方法如超声波法、热处理法等相比较,具有适应力强、操作可靠、运行简单等优点。     

酸-碱处理对剩余污泥水解酸化的影响

剩余污泥中富含有机质和营养元素可回收利用物质,污泥水解酸化液中的有机酸在去除或回收利用氨和磷后可作为进水化学需氧量(COD)不足的污水处理厂的补充碳源。通过控制pH,对比分析了不同处理方式(单独碱处理、酸-碱处理和碱-酸处理)对污泥水解酸化的影响。结果表明,单独碱处理的溶解性化学需氧量(SCOD)溶出量比酸碱联合处理要大16%左右,预处理第8天,达到5 406.1 mg/L。采用先酸(pH 4.0,4 d)后碱(pH 10.0,4 d)预处理,乙酸产量达到74.4 mg COD/g VSS,占总SCFAs的60.5%,产量及其占总短链脂肪酸(SCFAs)百分比含量均高于其他预处理方式。且酸-碱处理方式下NO4+-N和PO34--P溶出要优于其他处理方式。而单独碱处理方式下污泥减量效果最好,VSS去除率为36.6%。     

污泥和香蕉秸秆的配比对其厌氧消化特性的影响

城市污水处理厂污泥与香蕉秸秆以不同配比(质量比1∶0、2∶1、3∶1、1∶1、1∶3、1∶2和0∶1)进行中温((35±1)℃)厌氧消化实验,研究了不同配比下的产气特性,并考察了消化过程中消化液的挥发性脂肪酸(VFA)、溶解性化学需氧量(SCOD)、溶解性蛋白质、溶解性多糖以及总固体(TS)和挥发性固体(VS)的变化。结果表明:(1)污泥与香蕉秸秆进行混合厌氧消化可以明显提高系统的产气量。当污泥和香蕉秸秆的配比为1∶2时,累积产气量可达到339.12L/kg,分别比污泥和香蕉秸秆单独消化时提高了17.36%、31.25%。(2)当污泥与香蕉秸秆配比为1∶2时,TS、VS、SCOD、溶解性蛋白质和溶解性多糖的去除率都达到最大,分别为37.50%、22.66%、70.25%、58.71%、85.39%,此厌氧消化系统的稳定性良好。     

超声联合热碱预处理对剩余污泥厌氧消化的影响

以不同含固率剩余污泥为研究对象,在超声联合热碱预处理条件下,考察了污泥在厌氧消化过程中的减量以及细胞物质释放的特性。厌氧消化阶段,经过预处理作用的预处理泥挥发性悬浮固体(VSS)、溶解性COD(SCOD)的去除率均高于原泥,且VSS、SCOD去除率均随污泥含固率的增加而减少,SCOD去除率(X_(SCODr),%)和产气量(Y_(QY),mL/g)存在定量函数关系,即Y_(QY)=-0.148 7 X~2_(SCODr)+24.771 X_(SCODr)-775.68,同时SCOD去除率与VSS去除率(X_(VSSr),%)存在线性关系X_(SCODr)=0.533 3 X_(VSSr)+43.411。预处理对污泥在厌氧消化阶段氨氮、磷酸根磷的影响也随含固率的增大而减小,含固率为1.5%的预处理泥氨氮、磷酸根磷浓度相较原泥增幅最大,依次增长了97.3%、166.0%。     

减量脱水菌剂处理柠檬酸废水污泥的中试

利用规模为5m3的中试装置考察菌剂对柠檬酸废水污泥减量脱水效果的影响。结果表明:(1)满负荷运行阶段,菌剂处理后污泥的混合液悬浮固体质量浓度(MLSS)和混合液挥发性悬浮固体质量浓度(MLVSS)平均值分别为9.76、6.06g/L,比原污泥分别减量6.69%、12.93%;真空抽滤泥饼含水率平均值为78.12%,比原污泥下降11.87百分点;溶解性COD(SCOD)为214.40~323.71mg/L,平均值为279.69mg/L,相对于原污泥SCOD平均值,SCOD去除率可达到44.89%。说明菌剂可有效减少污泥量,改善污泥脱水效果,可进一步改善水质,对该柠檬酸废水污泥有着很好的针对性。(2)菌剂处理后污泥的脱水效果明显。较高压力、加入聚丙烯酰胺(PAM)及选用孔隙较小的滤纸均能进一步提高污泥的脱水效果。     

新型微生物菌剂在生活污水处理中的应用研究

对利用新的微生物源抗菌除臭剂去除生活污水中的COD、NH4 -N、TP及臭气的效果进行了评价.结果表明:(1)在好氧的条件下,当V菌液/V污水的比值为5/10 000～1/1 000时,COD的去除率提高幅度较大,为10%左右;当V菌液/V污水的比值为5/1 000时,对污水中NH4 -N的去除效果最好,增幅达37.62%;只有V菌液/V污水达到5/1 000以上时,对除磷才有较显著的促进作用,增幅约7%.(2)对污水除臭有很好的效果,不同嗅阈值的污水应选择适宜浓度的菌液.     

填料型A1/O1/A2/O2+垂直潜流式人工湿地处理乡村生活污水中的溶解性有机物三维荧光光谱特性分析

针对乡村生活污水中溶解性有机物(DOM)污染问题,为有效识别乡村生活污水的有机物组分,解析其转化规律,采用填料型A1/O1/A2/O2+垂直潜流式人工湿地(VFCW)组合工艺进行处理试验,考察了水力停留时间(HRT)对COD、氨氮、TN和TP的去除效果,并对各单元进出水DOM进行三维荧光光谱解析.结果表明,当组合工艺装...     

气浮与生化强化工艺在油田污水工程改造中应用

针对河南油田聚合物驱采油污水,定性分析了污水中的聚合物,研究了聚合物对污水COD的影响.结果表明,污水中聚合物的分子结构发生了一定的变化-CONH2水解为-COOH,同时测定了污水中1 mg/L部分水解聚丙烯酰胺(HPAM)贡献1.3 mg/L COD.随着3次采油技术的发展,油田污水中聚合物含量逐年增大,聚合物含量大幅上升是导致污水COD上升的根本原因.在原有处理工艺基础上,增加絮凝气浮处理工艺单元,改造工程采用“预曝气除油+絮凝气浮+A/O生物膜”处理工艺后,运行结果表明,出水COD为65 ～ 90 mg/L,达到《污水综合排放标准》(GB/T 8978-1996)一级排放标准.     

膜-生物反应器处理超市废水中污泥性质与膜污染关系分析

在以处理超市废水实际工程的基础上,通过对污泥性质中的胞外聚合物(EPS)、溶解性微生物产物(SMPs)、溶解性COD(SCOD)和污泥浓度(MLSS)变化的分析,得出EPS积累的原因是多方面的,而EPS的过度积累对沉降性能有一定的恶化作用;此外,EPS与SMPs有很好的相关性.作者采用SPSS软件对污泥性质与膜污染之间...     

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.