中低温厌氧处理城市污水污泥颗粒化的研究

用高径比为3：1的UASB反应器分别在35℃和室温条件下处理模拟城市污水,研究了污泥的颗粒化过程.比较了在不同温度、浓度下形成的颗粒污泥的特征.水温为9～25℃,进水浓度为100～200 mg COD/L,水力上流速度（Vup）在0.013～0.11 m/h的4^#UASB反应器在60 d内在形成了成熟的颗粒污泥.研究表明,进水中低的有机物浓度,低的Ca^2＋、Mg^2＋浓度和低的Vup没有抑制颗粒化进程.     

IC反应器厌氧氨氧化启动与运行特性研究

采用一套有效容积为20 L的IC反应器,接种啤酒废水厌氧处理池污泥,保持反应器进水NH+4-N浓度为120 mg/L,NO-2-N浓度为150 mg/L,在温度为30±1 ℃的条件下,对ANAMMOX反应过程的启动和运行特性进行了研究.结果表明反应器的启动经历了污泥低负荷驯化期、负荷提高期和高负荷运行期3个阶段;在反应器运行到第130 d,反应器启动成功;NH+4-N和NO-2-N的去除率分别约82.1%和94.5%;去除的NH+4-N和NO-2-N及生成的NO-3-N三者之间的比值为11.160.3;在反应器中形成了粒径为1～2 mm的颗粒污泥.     

垃圾渗滤液对厌氧颗粒污泥稳定性的影响

在升流式厌氧反应器中,分别以模拟废水和最优进水浓度渗滤液持续进水,探讨COD、NH+4-N和SO2-4浓度对反应器内颗粒污泥的稳定性的影响。结果表明,按照优化浓度进水,可以在一定程度上提高了厌氧生物处理效率,COD、NH+4-N和SO2-4去除率分别约为60%、11%和42%。渗滤液中微量元素(如Fe、Co和Ni等)有利于提高污泥浓度,增大反应器内生物量。改变垃圾渗滤液进水的COD、NH+4-N和SO2-4浓度,使得颗粒污泥多处于0.9~1.6 mm之间,具有高传质效率和不易破碎的特性。污泥颗粒的沉降速度保持在28.52~67.87 m·h-1之间,属于沉降性能良好的污泥。以最优进水浓度渗滤液为进水条件的反应器内的颗粒污泥浓度、粒径和沉降速度都要比模拟废水组更好,说明渗滤液中的微量元素存在,有利于颗粒污泥的稳定。     

常温下ABR处理低浓度废水性能及污泥特性

研究了常温(17~25℃)下4隔室厌氧折流板反应器(ABR)处理低浓度废水的运行效果及污泥特性。在水力停留时间(HRT)为24 h,进水COD浓度为1 500、1 000和500 mg/L左右时,平均COD去除率分别为94%、93%和87%。进水COD浓度保持在500 mg/L左右,将HRT降为12 h和8 h,COD的去除率仍达到83%以上。厌氧污泥性质测定结果表明,最后隔室中的污泥浓度、颗粒化程度及产甲烷活性与其他隔室相比明显较低,说明低浓度进水对最后隔室厌氧污泥的性质影响较大。颗粒污泥扫描电镜观察显示,各隔室颗粒污泥内部微生物组成差异较大,第1隔室颗粒污泥以产甲烷球菌为主,第2隔室颗粒污泥中没有明显的优势菌,但杆状菌比第1隔室明显较多,第3、4隔室颗粒污泥中以索氏甲烷丝菌为优势菌。     

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%。     

常温下IC反应器启动过程中的颗粒污泥性能研究

在常温下用自配葡萄糖废水启动IC反应器,研究了厌氧颗粒污泥的形成过程和特性。IC反应器进水浓度为3 000 mg COD/L,水温为14.5～26℃,25 d内形成了颗粒污泥。结果表明,随着运行时间和容积负荷的增加,颗粒污泥粒径逐渐增大。反应器启动完成后,反应器中2 mm的颗粒污泥增加到6.6%,0.3 mm的颗粒从57.7%减少到39.4%;VSS浓度从24.7 g/L上升到48.2 g/L;VSS/SS从34.4%增加到72.8%。颗粒污泥的沉降速度与颗粒粒径成正比,0.3～3 mm的颗粒污泥的沉降速度介于34.05～109.75 m/h之间,具有良好的沉降性能。初始接种污泥几乎没有产甲烷活性,与第30 d的初期颗粒污泥相比,成熟的颗粒污泥的产甲烷活性提高了46.7%。     

Ca2+对上流式多级厌氧反应器处理蔗渣渗滤液的影响

研究了上流式多级厌氧反应器(UMAR)处理蔗渣渗滤液过程中Ca2+浓度对反应器运行特性和颗粒污泥性质的影响。结果表明,对于蔗渣渗滤液而言,进水中低浓度的Ca2+浓度(80～300 mg/L)对颗粒污泥产甲烷活性无抑制,COD去除率最高可达93.3%;Ca2+浓度达到500 mg/L以上时,对厌氧颗粒污泥的活性有抑制作用;随着Ca2+浓度进一步升高,抑制作用加强,污泥灰分明显升高,活性成分下降,COD去除效率明显降低,污泥粘结沉积在反应器底部,导致系统内循环出现障碍。因此,在实际生产中应减少废水中Ca2+的引入量。     

混凝强化形成好氧颗粒污泥

为了缩短好氧颗粒污泥形成的时间,通过在颗粒污泥形成初期投加混凝剂的方式,研究强化造粒条件下颗粒污泥的形成过程及其特性。结果发现,投加混凝剂后,反应器在第8天出现了颗粒污泥,并在第25天时实现完全颗粒化,比未加混凝剂反应器颗粒形成的时间缩短了2 d,完全颗粒化时间缩短了10 d。强化造粒条件下形成的颗粒污泥,颗粒强度、比重分别为99.03%和1.1892,分别比对照高出3.28%和0.1539。可以看出,在混凝强化造粒条件下培养出的颗粒污泥,与常规方法相比具有颗粒化进程快,颗粒强度大,比重大等优点。     

C/N比对好氧颗粒污泥性能的影响

在SBR内接种活性污泥,研究了进水C/N比对好氧颗粒污泥的影响。结果表明,在高C/N比的条件下污泥不易快速颗粒化,沉降性能差,低C/N比有利于反应器内微生物的积累,MLSS最高可达8 740 mg/L,然而过低的C/N比将导致颗粒粒径增加,结构疏松以致解体,丝状微生物过度繁殖,不利于系统的稳定。对有机物的去除受进水C/N比的影响不明显,颗粒初步形成后对COD的去除率基本维持在87%左右;在C/N比为6.67～2.86之间时,除磷效果较好,平均去除率稳定在80%以上,而C/N比过高或过低,污泥颗粒化程度差,体系内缺乏除磷所需的微观环境,不利于磷的去除;进水C/N比对NH4＋-N的去除效果影响明显,C/N比为10时,好氧颗粒污泥具有良好的脱氮效果,NH4＋-N的平均去除率达90.59%,但低C/N比能抑制硝化菌和反硝化菌的活性,当进水C/N比由5降低至2时,反应器对NH4＋-N的去除率由65.23%下降到38.77%。     

不同乙酸钠浓度对UASB中颗粒污泥形成的影响

以污水处理厂厌氧消化池厌氧污泥作为接种物,采用上流式厌氧污泥床反应器(UASB),分别以不同配比的葡萄糖和乙酸钠为进水,考察厌氧颗粒污泥形成的特性。葡萄糖与乙酸钠进水COD浓度始终保持1∶1所形成的颗粒污泥其沉降性、产甲烷活性等均明显优于乙酸钠进水浓度始终为500 mg COD/L的颗粒污泥。结果表明,不同碳源配比的进水条件下形成的颗粒污泥性能及对废水处理能力存在显著差异。     

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.     

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.     

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.     

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.     

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.     

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.