序批式反应器处理垃圾渗滤液的污泥颗粒化及污染物去除性能研究

应用序批式反应器(SBR)处理垃圾渗滤液,以絮状活性污泥为接种污泥,经过37 d的运行,反应器内出现小粒径颗粒污泥。第50 d,反应器中污泥完全颗粒化。稳定运行期间,反应器内污泥的平均粒径为0.7 mm;SVI5min一直维持在较低的水平(27~47 mL/g);MLSS基本稳定在3 700~4 500 mg/L;当COD和氨氮的平均进水浓度为2 150 mg/L和312 mg/L时,平均出水浓度分别为540 mg/L和35 mg/L,去除率分别为75%和89%。     

活性污泥法处理高钙废水中污泥特性的变化

通过单级SBR法处理模拟高钙废水,研究了活性污泥法处理高钙废水的过程中钙离子对COD,MLVSS,MLSS,SVI,污泥增长速率,污泥形态结构及生物相的影响,揭示活性污泥法处理高钙废水的过程中污泥量巨大的原因。采用逐步增加钙离子浓度的方法,检测到在污泥培养期([Ca2+]=0 mg/L),COD去除率为98.1%,MLVSS和MLSS稳定在4 900~5 500mg/L,污泥增长速率为67 mg/(L·d),SVI为55~60 mL/g;在驯化处理期([Ca2+]=120~2 400 mg/L),COD去除率降至87.37%,MLVSS降至2 500 mg/L,MLSS增加至19 300 mg/L,污泥增长速率为212.31 mg/(L·d),SVI降至25 mL/g;在冲击期([Ca2+]=4 000 mg/L),COD去除率降至69.23%,MLVSS降至1 600 mg/L,MLSS迅速增加至24 200 mg/L,污泥增长速率为816.67 mg/(L·d),SVI降至14 mL/g。经显微镜观察发现,污泥絮体由松散变得密实,生物相由钟虫等指示性微生物变为不适应环境的胞囊结构。结果表明,随Ca2+浓度的增加,COD去除率下降,MLSS迅速增加,MLVSS和SVI急剧缩小,说明活性污泥中的活性微生物逐渐减少,而无机物组分逐渐增多;钙离子的加入促使系统碳酸平衡向右移动,使离子状态的钙大部分转化为难降解的碳酸盐,并附着于污泥絮体上,污泥绒粒被压缩,使污泥颗粒密实度及MLSS迅速增加,导致污泥排放量巨大。     

A/O+MBR工艺处理玉米深加工废水的中试研究

实验基于企业污水站的改造工程,研究了MBR对玉米深加工废水的处理效果并对工艺运行参数优化提出建议.结果表明,该工艺对COD的去除率可以达到90％以上,出水稳定在26 mg/L左右;出水NH4-N达到1 mg/L以下;TN去除率达到70％以上,出水TN达到10 mg/L以下,出水完全达到排放标准.通过4种工况的比较,说明在污泥浓度8 g/L左右,曝气池内DO在3 mg/L左右,MBR内DO＞4 mg/L,好氧段停留时间13.5 h,并保证3h以上的缺氧段水力停留段时间的条件下,A/O+ MBR工艺可以有效去除玉米深加工废水中的污染物.     

ABR-好氧颗粒污泥处理黄连素废水的启动研究

实验研究了ABR-好氧颗粒污泥组合工艺处理黄连素制药废水的启动运行,通过分析发现,ABR装置在HRT为4 d,黄连素浓度为50 mg/L的运行方式下成功启动,反应器运行稳定后每个格室MLSS平均值分别为25 840、21 560、27 500和11 200 mg/L。以ABR出水为营养物,成功培养出粒径在2～10 mm,沉降速率为104～137 m/h,沉降性能优良的好氧颗粒污泥。该组合工艺在启动实验的末期,进水COD浓度为3 000～4 000 mg/L左右,出水COD浓度到达168.4～271mg/L,系统总的去除率保持在90%～95%之间,表明ABR-好氧颗粒污泥组合工艺能够有效地处理黄连素制药废水。     

A/O-MBR中MLSS浓度对污泥性能及膜通量的影响

采用国产聚丙烯中空纤维帘式膜组件,进行了A/O-MBR系统处理生活污水的实验研究,主要探讨了系统中污泥浓度(MLSS)与膜通量变化过程的关系。实验结果表明,MLSS由3 805 mg/L升高到6 912 mg/L时,污泥混合液胞外聚合物(EPS)由43 mg/g VSS增加到81 mg/g VSS,EPS中多糖与蛋白质的比例从0.87增加到1.08。同时,污泥相对疏水性(RH)的降低与Zeta电位的升高也在一定程度上共同促进了膜污染速率的上升。实验条件下,当运行时间为60 d左右,MLSS升高至6 200 mg/L时,跨膜压差上升迅速,膜组件清洗周期由初始的22 d缩短为11 d。A/O-MBR中由于MLSS浓度变化而导致的活性污泥混合液特性的变化,是影响膜通量变化的重要原因。     

改性无纺布膜生物反应器处理聚酯工艺废水研究

采用自制壳聚糖改性聚丙烯无纺布膜为膜组件的A/O-MBR(厌氧/好氧-膜生物反应器)工艺对聚酯工艺废水的处理进行了研究,并与PVDF商品膜性能进行了比较研究。在近70 d的运行中,当进水COD在200~500 mg/L之间,总氮在30~45 mg/L之间波动时,2种平板膜出水水质稳定。出水COD40 mg/L,NH4+-N0.5 mg/L,TN5 mg/L,浊度0.2 NTU,均满足回用水水质要求和最新的辽宁省废水排放标准。实验中考察分析了污泥浓度和COD/TN对总氮去除率的影响。对比2种膜的运行结果,改性聚丙烯无纺布膜的出水水质略好于PVDF商品膜,但过膜压力稍大、膜通量稍小。     

污泥减量过程中臭氧氧化对硝化和反硝化影响的试验研究

采用AO工艺,考察了在污泥减量过程中臭氧(O3)氧化对生物系统硝化和反硝化能力的影响.结果表明,在每克SS中O3投量为0.05 g时,氧化后污泥中的CODcr由37.5 mg/L增至700mg/L,TN由4.86 mg/L增至36.6 mg/L,NH4 -N由0.353mg/L增至7.49 mg/L,NO3--N由2.19 mg/L增至5.15 mg/L.虽然氧化系统出水NH4 -N浓度略高于对照系统,但氧化系统NH4 -N的去除率大于98%,硝化能力基本没有受到O3氧化的影响.O3氧化污泥后增加的有机物作为附加的碳源循环至缺氧段,提高了反硝化的效果,当污泥氧化比例分别为10%、20%、30%时,进入缺氧段的CODCr/TN分别平均增至11.21、11.56、11.88,氧化系统的反硝化效果也随之分别提高5%、25%、37%.     

生活污水PVA生物处理工艺

采用PVA生物处理工艺对某高校生活污水(COD 140~270 mg/L,NH_4~+-N 20~50 mg/L)进行处理。结果表明:PVA生物系统(85 L)在容积负荷1.5 kg COD/(m~3·d)连续运行25 d,系统平均每天处理水量达到272 L,出水平均COD和NH_4~+-N浓度分别达到27.9 mg/L和1.3 mg/L,此外,经紫外消毒后最终出水菌落数降至1.0×10~4个/L以下;扫描电镜观察发现,PVA凝胶小球表面和内部均富含大量球菌、丝状菌和杆菌;该系统25 d连续运行过程中污泥产率仅为0.08MLSS/COD_(removed),无污泥外排。     

厌氧-好氧颗粒污泥SBR处理城市污水的中试研究

采用中试规模的厌氧-好氧交替式颗粒污泥SBR处理实际城市污水,研究了好氧颗粒污泥的培养过程、处理效果及颗粒污泥的特性。以絮状活性污泥为接种污泥,经过72 d的培养后,反应器内出现小粒径颗粒污泥。在随后的230 d运行实验中,通过调整曝气阶段的溶解氧浓度、排水体积交换率以及周期运行方式,使得反应器中颗粒污泥粒径和比例逐渐增加。在最佳工况运行条件下,反应器中污泥浓度为3 000～4 000 mg/L,SVI值为45～55 mL/g,对COD、氨氮、总氮和总磷的平均去除率分别为91.63%、74.02%、68.42%和96.41%,达到了同时脱氮除磷的效果。     

高浓度氨氮对IC厌氧反应器运行的抑制性研究

在中温(35±1)℃条件下,以葡萄糖为有机碳源,研究氨氮对IC厌氧反应器运行的影响.实验结果表明,氨氮浓度超过3 036 mg/L时对反应器的运行有抑制作用,随着氨氮浓度的增加,抑制作用更加明显,氨氮对系统的IC50为4 500 mg/L;系统运行过程中VFA低于400 mg/L,pH值和碱度分别维持在7.21～7.62之间和2 356～3 065 mg/L之间;反应器对氨氮的平均去除率为12.67%.在毒性恢复实验中,7 d后COD去除率恢复到93.01%;恢复期系统VFA逐渐降低,从第6 d开始维持在152～162 mg/L之间;出水碱度和pH值维持在1 769～2 298 mg/L和7.09～7.27之间,系统运行稳定.     

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.     

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.     

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.     

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.     

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.     

Patterns of volatile metabolites and nonvolatile trichothecenes produced by isolates of <Emphasis Type="Italic">Stachybotrys,Fusarium, Trichoderma,Trichothecium</Emphasis> and <Emphasis Type="Italic">Memnoniella</Emphasis>

We reported previously that trichodiene, a volatile trichothecene derivative, was produced by a Stachybotrys isolate, also known to produce highly cytotoxic, non-volatile, macrocyclic trichothecenes (satrotoxins). We investigated the relationship between the production of trichodiene and various non-volatile trichothecenes for several molds. Volatile metabolites were concentrated by adsorption on Tenax TA and analyzed by GC/MS, while non-volatile metabolites were separated by HPLC, derivatized and analyzed by GC/MS. Stachybotrys chartarum isolates producing macrocyclic trichothecenes secreted significantly larger amounts of trichodiene and other sesquiterpenes than isolates which only produced simple trichothecenes. The amounts of secreted trichodiene were relatively small in all cases. With the exception of Memnoniella, which excreted small amounts of sesquiterpenes, the other isolates produced varying amounts of sesquiterpenes, including trichodiene, as well as simple tricothecenes, no detectable trichodiene, but large amounts of griseofulvin derivatives. In Stachybotrys there is apparently a correlation between trichodiene and macrocyclic trichothecene production. In the remaining isolates, there was no simple relationship between trichodiene and non-volatile trichothecene synthesis. Trichodiene is produced in larger amounts by Stachybotrys isolates, which also produce satratoxins, but it will be difficult to utilize this metabolite to detect toxic isolates in buildings due to the relatively small amounts excreted.     

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.     

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.     

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.     

Knowledge transfer initiative between molecular biologists and environmental researchers and regulators

A Natural Environment Research Council (NERC) funded Knowledge Transfer (KT) workshop was held in the United Kingdom (UK) to identify the needs and opportunities in the application of molecular biology and ‘omics’ techniques to environmental monitoring and risk assessment. Attendees highlighted a lack of effective communication between end-users and researchers as well as difficulties with data interpretation as reasons behind the slow uptake of molecular biology and omics techniques. A number of promising areas in which new techniques could be implemented at a practical level in the very near future were identified, thereby raising the profile of these recent technologies and providing vital proof of concept work. Molecular taxonomy, bacterial source tracking and pre-screening of chemicals for potential toxicities were all viewed as areas in which omics and molecular techniques could have immediate value, with the aim of reducing cost, increasing efficiency and providing more comprehensive data of improved quality.