高氨废水短程硝化特性

采用SBR装置,针对高氨废水的特点,在高氨条件下,以高氨低氧为转化手段,实现高氨废水短程硝化过程中亚硝化菌的驯化与积累。控制温度为28~31℃,曝气量为15~60 L/h,pH控制在7.8~8.2的条件下连续运行78 d。实验结果表明,运行11 d后实现了短程硝化,从11 d至78 d属于系统氨氮负荷提高期。在运行过程中,氨氮污泥负荷从开始的0.023 kg/(kg·d)逐步上升为0.3 kg/(kg·d),最高时达到0.34 kg/(kg·d),此时氨氮去除率仍维持90%以上。为观察驯化后短程硝化菌的形态,取驯化好的污泥进行电镜扫描,结果表明,污泥中的细菌形态主要以球状菌为主。     

短程硝化处理炼油催化剂废水

炼油催化剂生产过程中产生的高盐度、高无机质的高氨氮废水难以处理。研究将短程硝化反硝化生物脱氮技术应用于该种废水的处理。实验同时控制反应器温度(31℃)、溶解氧(≤1.5 mg/L)、pH值(7.8~8.7)和污泥龄(30 d),较快地实现催化剂废水短程硝化污泥的驯化,亚硝酸盐平均积累率达到了97.4%。在此基础上,结合在线监控ORP、pH值变化情况及短程硝化反应动力学研究,较好地实现了炼油催化剂废水的短程硝化。     

固定化包埋填料高氨氮负荷下短程硝化稳定运行特征

为了探讨固定化包埋填料高氨氮负荷下短程硝化的稳定运行研究,以固定化技术包埋一定量硝化菌填料为载体,并利用序批次反应器进行处理人工配置的氨氮废水实验,该实验研究了实现短程硝化影响因素DO、有机物的控制范围,驯化期间,分别将温度、pH值、DO控制在(31±1)℃、7.8~8.2、1.8~2.0 mg·L~(-1)范围内,进水有机物浓度始终保持在50 mg·L~(-1)以下,体积填充率为15%,采用高游离氨(3.03~14.18 mg·L~(-1))对NOB产生抑制作用,使活性填料中的AOB成为优势菌群,通过历时55 d的培养实现了该填料短程硝化的启动及稳定运行,结果表明,进水氨氮浓度保持200 mg·L~(-1)左右,氨氮去除速率高达28.29 mg NH+4-N·(L·h)~(-1)的同时,氨氮的去除率97%,亚硝酸盐积累NO_2~--N/NO_x~--N85%,实验同时还考察了活性填料的抗冲击负荷能力与单个周期内短程硝化运行特征。     

处理畜禽废水的序批式生物膜反应器中的细菌多样性

采用序批式生物膜反应器(SBBR)处理畜禽废水,在室温(9～18℃)下,采用8 h/周期、交替停曝气的模式运行,控制曝气阶段DO浓度在2 mg/L,可实现明显的亚硝酸盐积累,氨氮及总氮的去除率分别可达(95.1±0.8)%和(87.2±0.6)%。为揭示SBBR中细菌种群构成及其动态变化规律,采用PCR-DGGE技术进行了细菌多样性分析,并构建了系统发育树,结果表明:与接种污泥相比,驯化期生物膜中细菌种群丰富度未发生明显变化,运行期交替曝气、停曝模式有助于提高生物膜中细菌的多样性指数,但受运行模式及氨氮负荷变化影响,运行期氨氧化菌多样性指数略低于驯化期;生物膜内存在一些具有反硝化功能的变形菌和特殊的氨氧化细菌,在本实验条件下未发现厌氧氨氧化菌,说明主要脱氮机理为同时短程硝化反硝化。     

炭管膜曝气生物膜反应器SNAD脱氮研究

以包裹无纺布的微孔炭管作为膜曝气生物膜反应器（MABR）的膜组件，进行了短程硝化，厌氧氨氧化和反硝化耦合脱氮(SNAD)研究。实验中，控制温度34±1℃，pH 7.5～8.5, HRT 8 h，通过逐步降低膜内压力使反应器中的溶解氧由8 mg/L逐步降低到0.5 mg/L以下。实验采用亚硝酸细菌挂膜，然后接种厌氧氨氧化细菌，实现在单一反应器中同时发生短程硝化、厌氧氨氧化和反硝化耦合脱氮功能。结果表明，经过180 d的连续稳定运行，氨氮去除率达到了93.4%，总氮去除率达到了92.5%，COD去除率达到97.2%, 氨氮去除负荷0.6 kg N/（m³ ·d）。适合SNAD工艺的最佳C/N比为0.2～0.6，当COD浓度过高时，会抑制厌氧氨氧化细菌，使SNAD工艺的处理效果明显下降。     

亚硝化颗粒污泥处理低碳高氨氮废水的影响因素

稳定的部分硝化是新型脱氮工艺处理低C/N比高氨氮废水的关键环节。在SBR中,以放置超过30d的亚硝化颗粒污泥为接种污泥,考察反应器内快速启动亚硝化的可行性和污泥形态变化,探讨pH和C/N比对颗粒污泥性能和氮转化的影响。结果表明,通过提高进水负荷可快速启动亚硝化反应器,氨氮去除率和亚硝酸盐累积率均在90%以上,由同步反硝化引起的氮损失为20%左右。降低进水pH至7.0,SBR周期运行最高游离氨FA浓度为5.1mg·L~(-1),有利于NOB选择性抑制,提高氨氮去除率,出水NO_2~--N/NH_4~+-N比值从0.5提高到0.95左右。C/N比高于2,会引起异养微生物的快速增殖,COD去除负荷提高了1.45kg·(m~3·d)~(-1),AOB受显著抑制,出水NO_2~--N/NH_4~+-N由1.0降低至0.65左右,出现颗粒污泥破裂、解体。     

耐酸厌氧消化污泥处理餐厨垃圾简

采用耐酸驯化的厌氧消化污泥处理餐厨垃圾，在酸性条件下（pH=4.5），对实验装置容积负荷从1.0 kg VS/（m³·d）分9次逐级增加到5.0 kg VS/（m³·d）的过程进行了跟踪监测，并较深入地研究了驯化污泥代谢活性和处理效果。实验结果表明，pH 4.5的耐酸厌氧消化污泥，最佳投加负荷约为4.5 kg VS/（m³·d），此负荷下容积产气率，CH₄含量平均值均达最大，分别为1.68 m³/（m³·d），75.0%。耐酸厌氧消化装置持续增料运行46 d，产甲烷菌仍能保持较高的活性，其COD去除率范围为40.4%~75.0%，仍能保持pH 7.2时处理效果的65.0%~91.8%，表明在低pH、低碱度下实现稳定的产甲烷过程是可行的。     

有机物浓度对厌氧氨氧化脱氮性能影响试验研究

通过间歇试验和连续试验研究了不同有机物浓度对厌氧氨氧化活性及脱氮性能的影响。间歇试验结果表明：自养条件下厌氧氨氧化菌的最大比反应速率为0.189 kg NH⁺₄-N/（kg VSS·d）；当氨氮和亚硝酸盐氮浓度为80 mg/L时，有机物的添加降低了厌氧氨氧化速率，当有机物浓度超过70 mg/L时，厌氧氨氧化菌的最大比反应速率降低到0.05 kg NH⁺₄-N/（kg VSS·d）以下，是反硝化菌与厌氧氨氧化菌竞争亚硝酸盐产生了可逆抑制的结果。连续试验结果表明，高氮低碳源有机环境下厌氧氨氧化能稳定运行，并且比自养系统中总氮的去除率有所提高，当COD值为50 mg/L时，总氮去除率最大，平均值达96.59%，是反硝化菌和厌氧氨氧化菌共同脱氮的结果；当有机物浓度过高时，ANAMMOX对TN去除贡献率持续降低，反硝化不断得到强化，厌氧氨氧化运行不稳定。     

晚期垃圾渗滤液短程硝化影响因素研究

采用固定化微生物曝气生物滤池（I－BAF），探讨了水力停留时间（HRT）、游离氨（FA）、pH、溶解氧（DO）对晚期垃圾渗滤液短程硝化的影响和碳氮比（C/N）对同步脱氮的影响。试验结果表明，在HRT为2 d，对应氨氮负荷为0.26～0.3 g/L·d，保持出水FA在1 mg/L以上，pH在79左右，DO控制在1.3±0.2 mg/L时，最利于实现短程硝化。DO是影响短程硝化的决定性因素，DO＞1.6 mg/L时，短程硝化可能向全程硝化转化。投加碳源NaAc并控制C/N在1.6～2.2，可以使部分亚硝氮直接通过同步反硝化去除，提高总氮去除率。     

基于SBBR的单级自养脱氮快速启动

以普通活性污泥为接种污泥,采用人工配制无机氨氮废水进行单级自养脱氮工艺快速启动研究。启动过程经历了污泥适应期、部分短程硝化选择期以及单级自养脱氮实现期3个阶段。经过29 d的培养驯化,通过控制游离氨的方法实现了部分短程硝化。当出水中亚硝酸盐积累率达到60%左右时,立即将序批式生物膜反应器(SBBR)由连续曝气改为间歇曝气,间歇曝气使得厌氧氨氧化菌(AAOB)的富集与亚硝酸氧化菌(NOB)的淘汰同时进行,并且避免了高浓度亚硝酸盐对AAOB的抑制作用,从而实现了单级自养脱氮的快速启动。实验仅用50 d成功启动了SBBR单级自养脱氮工艺,总氮容积去除负荷达到0.173 kg N/(m3·d),氨氮的平均去除率达到98.68%,总氮的平均去除率达到80.87%。成功启动之后,反应器内只有少量的悬浮污泥,大部分的污泥都附着在填料上,污泥颜色呈褐色,而反应器内壁及出水管上附着的污泥呈浅砖红色,表明反应器内富集了大量的AAOB。     

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.     

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.     

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.