盐度对活性污泥硝化功能的影响

利用批量试验研究了盐度对常规活性污泥(非耐盐污泥)硝化功能的影响;通过逐步提高试验水的NaCl浓度驯化活性污泥,考察了驯化污泥的硝化功能;并进一步研究了适应于某NaCl浓度的耐盐硝化菌在受到盐度冲击时,其硝化功能的变化.结果表明,常规活性污泥中的硝化菌对盐度较敏感,当试验水中的NaCl质量浓度达到10.0 g/L时,污泥比硝化速率降低86%;通过逐步提高试验水的NaCl浓度对活性污泥进行长期驯化,可以驯化出耐盐硝化菌,耐盐污泥的比硝化速率接近于常规活性污泥的比硝化速率;适应于某NaCl浓度的耐盐硝化菌在受到盐度冲击时,NaCl浓度突然增加会对其产生更强的抑制作用.     

SFBR工艺顺序进行硝化和反硝化的动力学研究

采用序半连续式反应器(sequencing fed-batch reactor,简称SFBR)对人工合成废水顺序地进行硝化和反硝化动力学进行了研究.硝化和反硝化所用微生物为活性污泥.反应器在不同的操作条件进行操作,获得了用于确定动力学常数的数据;获得动力学参数um=0.05 h-1,KNO=2.0 mg/L,y=0.47 mg X/mg N,a=0.001 h-1.类似地确定了反硝化动力学参数kD=0.01 h-1和KD,NO=0.4 mg/L.在一定范围内硝化和反硝化速率随着氨浓度和硝酸盐浓度的增加而增加.实验数据表明,硝化和反硝化的动力学符合Monod动力学方程.     

SFBR工艺顺序进行硝化和反硝化的动力学研究

采用序半连续式反应器（sequencing fed-batch reactor,简称SFBR）对人工合成废水顺序地进行硝化和反硝化动力学进行了研究.硝化和反硝化所用微生物为活性污泥.反应器在不同的操作条件进行操作,获得了用于确定动力学常数的数据;获得动力学参数um=0.05 h-1,KNO=2.0 mg/L,y=0.47 mg X/mg N,a=0.001 h^-1.类似地确定了反硝化动力学参数kD=0.01 h^-1和KD,NO=0.4 mg/L.在一定范围内硝化和反硝化速率随着氨浓度和硝酸盐浓度的增加而增加.实验数据表明,硝化和反硝化的动力学符合Monod动力学方程.     

盐度对活性污泥驯化前后硝化特性的影响

通过批量试验系统研究了盐度对常规活性污泥硝化作用的影响以及污泥在含盐环境中经过驯化后其硝化功能的变化.试验结果表明,硝化菌比亚硝化菌对盐度更敏感,废水中含盐浓度为5 g/L时,对常规活性污泥中的亚硝化菌影响不大,硝化菌会受到一定程度的抑制;当含盐浓度超过10 g/L时,硝化菌和亚硝化菌均会受到严重抑制;含盐浓度大于30 g/L时,亚硝化菌和硝化菌已经完全受到抑制.在污泥驯化初期,耐盐硝化菌群数量较少,比硝化速率较低,硝化产物中亚硝态氮大量积累;随着驯化时间的延长,耐盐硝化菌群数量增加,比硝化速率增加,亚硝态氮累积量减少.污泥经过驯化后,硝化菌群可以逐渐适应高盐环境,在含盐浓度为30 g/L时硝化反应仍能进行.     

硫脲对硝化反应的抑制

利用富集培养的硝化污泥,在间歇式反应器中通过测定氨氮降解速率和溶解氧消耗速率,研究了硫脲对硝化过程的抑制特性及动力学方程。结果表明,硫脲对硝化反应抑制现象明显,0.05 mg·L~(-1)硫脲即可使相同时间内的氨氮降解率降低12%,氨氮最大降解速率降低21%。硫脲对硝化菌的抑制类型为非竞争性抑制,抑制常数KI和EC50值相等,均为0.14 mg·L~(-1),并且硫脲主要对硝化过程中的亚硝化过程造成抑制。     

pH对高浓度氨氮短程硝化抑制动力学的影响

在移动床生物膜反应器(MBBR)实现稳定短程硝化的前提下,采用模拟废水进行批式实验,研究生物膜短程硝化过程的基质抑制动力学特性及pH的影响.基于Haldane模型建立短程硝化基质抑制动力学方程,确定不同pH条件下的动力学常数.结果表明,不同pH条件下,高浓度氨氮对短程硝化的抑制特性均符合Haldane模型.pH为7.0、8.0和9.0时的氨氮最大比降解速率(qmax)分别为9.906、16.234、14.742mg/(g·h),pH=8.0是获得高效的短程硝化效果的适宜运行条件.但半亚硝化的实现则需要在氨氮降解速率适当降低的条件下(pH=7.0)才能实现.     

颗粒污泥反硝化动力学特性及微量NO2的影响

采用批试验方法,研究了颗粒污泥反硝化动力学特性及微量NO2的影响.采用Monod模型描述反硝化反应动力学,得到有机物半饱和常数为4.72 mg/L,亚硝态氮半饱和常数为2.26 mg/L,最大亚硝态氮降解速率为0.0069 mgNO2--N/(mg MLSS·h).微量NO2对反硝化具有抑制作用,采用反竞争性可逆抑制模型描述了微量NO2对反硝化速率的影响,得到微量NO2下的最大反硝化速率为0.006865 mg NO,2--N/(mg MLSS·h),亚硝态氮半饱和常数为0.1 mg/L,NO2抑制系数为1.53 mg/L.在通入51.3、102.7、205.4和308.1 mg NO2/m3时Nox的损失量分别是78.7%～99.4%、81%～99.4%、65.1%～97.9%和38.9%～89.7%,相当部分的Nox损失.     

序批式活性污泥法工艺处理含盐废水动力学模型研究

为了实现含盐废水序批式活性污泥法(SBR)工艺的启动,采用逐步提高废水中NaCl浓度负荷的方法对活性污泥进行驯化,并建立有机物(COD)与NH4+-N的降解动力学模型。结果表明,经过280d的驯化和稳定运行,SBR系统可以有效降解含盐废水,COD去除率高于74%,NH4+-N平均去除率高于90%,实现了SBR工艺处理含盐废水的启动和稳定运行。含盐废水有机物(COD)降解动力学参数r0(无盐条件下的COD去除速率)为129.87mg/(L.h),KY(盐抑制常数)为7700.01mg/L;含盐废水硝化反应动力学参数Ks(饱和常数)为186.52mg/L,vmax(NH4+-N的最大比降解速率)为0.0034h-1。     

微量NO2对厌氧氨氧化甲烷化反硝化耦合影响的动力学分析

采用批试验方法,研究微量 NO2对颗粒污泥厌氧氨氧化、甲烷化和反硝化耦合的影响.基于 Haldane 模型建立了厌氧氨氧化的 NO2 强化函数,估计了强化函数中的最大强化系数(30.55)、NO2 半饱和常数(1.96 mg/L)、NO2 抑制常数(0.0082 mg/L)和基础速率系数(0.0314).微量 NO2 对甲烷化和反硝化动力学可用反竞争性抑制动力学方程进行描述.甲烷化的最大比乙酸盐去除速率为0.15 mg COD/(mg VSS·h),乙酸盐半饱和常数为395 mg COD/L,NOz抑制系数为0.623 mg/L.反硝化的亚硝酸盐氮最大去除速率 0.00685 h-1,亚硝酸盐氮半饱和常数0.214 mg/L,NO2 抑制系数为22.4 mg/L.试验中大部分的 NOx 气体物质出现损失.     

2种温度下污泥水富集硝化菌的对比

污泥水富集硝化菌添加强化硝化工艺可以在处理高温、高浓度氨氮污泥水的同时富集硝化菌并添加至城市污水处理系统强化硝化,但硝化菌对温度敏感,温度将对硝化菌的富集效果产生影响。研究在高氨氮负荷(1.20 kg·(m~3·d)~(-1))下运行SBR以富集硝化菌,对比2种温度(25℃、30℃)下富集硝化菌的群落结构和动力学特性。荧光原位杂交结果表明,硝化菌r-决策者(Nitrosomonas europaea,Nitrobacter)的份额随温度升高而逐渐增加。硝化动力学参数测定发现,随温度升高,AOB活性增加,基质半饱和常数增加;而NOB则相反,这主要是因为温度升高,反应器中最大游离氨(FA)、游离亚硝酸(FNA)浓度增加,而NOB比AOB更容易受FA、FNA的抑制。此外,温度对AOB与NOB的溶解氧半饱和常数无明显影响。     

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.     

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.     

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.     

Radionuclides and trace elements in fish collected upstream and downstream of Los Alamos national laboratory and the doses to humans from the consumption of muscle and bone

Abstract

The purpose of this study was to determine radionuclide and trace element concentrations in bottom‐feeding fish (catfish, carp, and suckers) collected from the confluences of some of the major canyons that cross Los Alamos National Laboratory (LANL) lands with the Rio Grande (RG) and the potential radiological doses from the ingestion of these fish. Samples of muscle and bone (and viscera in some cases) were analyzed for ³H, ⁹⁰Sr, ¹³⁷Cs, ^totU, ²³⁸Pu, ^239,240Pu, and ²⁴¹Am and Ag, As, Ba, Be, Cr, Cd, Cu, Hg, Ni, Pb, Sb, Se, and Tl. Most radionuclides, with the exception of ⁹⁰Sr, in the muscle plus bone portions of fish collected from LANL canyons/RG were not significantly (p<0.05) higher from fish collected upstream (San Ildefonso/background) of LANL. Strontium‐90 in fish muscle plus bone tissue significantly (p<0.05) increases in concentration starting from Los Alamos Canyon, the most upstream confluence (fish contained 3.4E‐02 pCi g^‐1 [126E‐02 Bq kg^‐1]), to Frijoles Canyon, the most downstream confluence (fish contained 14E‐02 pCi g^‐1 [518E‐02 Bq kg^‐1]). The differences in ⁹⁰Sr concentrations in fish collected downstream and upstream (background) of LANL, however, were very small. Based on the average concentrations (±2SD) of radionuclides in fish tissue from the four LANL confluences, the committed effective dose equivalent from the ingestion of 46 lb (21 kg) (maximum ingestion rate per person per year) of fish muscle plus bone, after the subtraction of background, was 0.1 ± 0.1 mrem y^‐1 (1.0 ± 1.0 μSv y^‐1), and was far below the International Commission on Radiological Protection (all pathway) permissible dose limit of 100 mrem y^‐1 (1000 μSv y^‐1). Of the trace elements that were found above the limits of detection (Ba, Cu, and Hg) in fish muscle collected from the confluences of canyons that cross LANL and the RG, none were in significantly higher (p<0.05) concentrations than in muscle of fish collected from background locations.     

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.