碳氮比对人工湿地污水处理效果的影响

采用表面流人工湿地系统静态小试装置,考察了低、中、高3组不同进水COD/N(2,5,10)对系统中氮、磷及COD去除效果的影响。结果表明:进水C/N的变化对COD的去除率影响不大,平均去除率达到94.6%。TN的去除率随着COD/N的增大而逐渐升高,在C/N=5时达到63.8%,继续提高COD/N,TN的去除率变化不大。NH4+-N去除率随着COD/N的增加而降低。随着碳源的增加,释磷菌能够从进水中获得充足的碳源,从而可以比较充分地释磷,因此,磷的去除率随COD/N的增加而提高。     

COD浓度和进水流量比对一体化工艺脱氮除碳的影响

保持进水总流量不变，以一定流量比同时从缺氧区和厌氧区进水，探讨了不同进水流量比(R=Q_厌/Q_缺)和进水COD浓度对中心岛式一体化OCO工艺脱氮除碳的影响。研究结果表明，进水COD浓度和进水流量比Rs对COD的去除效果影响不大，出水COD浓度一直稳定在50 mg/L以下，去除率在92%以上；进水COD浓度和进水流量比Rs共同决定着系统TN的去除效果，进水COD浓度为100 mg/L、200 mg/L时，TN去除率随着进水流量比Rs的减小呈增加的趋势；当进水COD浓度为 300 mg/L时，TN去除率随着进水流量比Rs的减小呈先升高后降低的趋势，在进水流量比Rs为3∶1时TN去除率最高，达到87%。     

C/N对Carrousel 2000氧化沟同步脱氮除磷的影响研究

就C/N对Carrousel 2000氧化沟同步脱氮除磷的影响进行了研究。结果表明，进水C/N值在5～13之间时，进水C/N不影响氧化沟系统对NH₃-N的去除效果。出水NH₃-N浓度＜1 mg/L，平均去除率达到97.40%。当C/N低于11时，TN、TP的去除率随C/N的升高而快速大幅提高，分别从5时的26.47%和14.99%升至11时的93.48%和97.03%。当C/N＞11时，氧化沟TN去除率达到93.48%，TP去除率接近100%，氧化沟具有了良好的同步脱氮除磷的效果，出水水质满足国家《城镇污水处理厂污染物排放标准》(GB 18918-2002一级A标准)要求。TP去除率与TN去除率相关系数R₂＝0.985。     

侧沟式一体化OCO工艺中DO和C/N对同步硝化反硝化的影响

以自配模拟生活污水为处理对象,研究了不同DO和C/N对侧沟式一体化OCO反应器同步硝化反硝化和COD降解效果的影响。实验结果表明,维持进水COD均值约为300 mg/L,TN约为40 mg/L,MLSS约为2 600 mg/L,进水流量为20 L/h时,COD去除率随着DO的增大逐步提高,当好氧区DO均值约为2.0 mg/L时,同步硝化反硝化效果最好,TN去除率达到了80%以上;维持好氧区DO均值约为2.0 mg/L,MLSS约为2 600 mg/L,进水流量为20 L/h时,不同C/N对COD去除率影响不大,当进水C/N约为8时,同时硝化反硝化效果最好,TN去除率均值达到了82%。     

一体化A/O工艺碳氮比对脱氮除碳的影响

依据好氧硝化和缺氧反硝化生物脱氮除碳工艺原理，设计了一体化生物膜法A/O反应器，并将其应用于生活污水处理，取得了理想的处理效果。实验结果表明，水力停留时间HRT＝12 h，COD进水浓度处于150～500 mg/L范围内，COD的去除率均在90%以上，且出水均在40 mg/L以下；当C/N比为8.5以下时，NH₃-N去除率高于90%，其出水浓度小于5 mg/L；当C/N比为7.5左右时，具有较高的总氮脱除效果，TN去除率可达到70%。     

序批式膜生物反应器处理猪场沼液中氮的影响因素研究

猪场沼液具有高氨氮、低碳氮比(C/N)和脱氮难度大等特点,实验采用序批式膜生物反应器进行处理。结果表明,为达到较好的脱氮效果,进水COD宜控制在800~1 000mg/L;NH3-N为800mg/L时不会抑制硝化反应,C/N越高脱氮效果越好,C/N从8下降到1时,TN去除率由82.2%下降为16.7%;pH为8.5时脱氮效果最佳;夏天(进水水温25℃)脱氮效果优于冬天(进水水温13℃),TN去除率分别为93.13%、81.31%,进水水温在10~30℃时,进水水温越高脱氮效果越好。     

MBBR与A/O法对污水中有机物及氮处理效果的研究

实验在不同水力停留时间（HRT）、进水COD浓度和不同COD容积负荷条件下考察了移动床生物膜反应器（MBBR）和活性污泥A/O工艺对污水中有机物及氮的处理效果。结果表明,MBBR工艺去除有机物和脱氮效果均优于A/O工艺。在进水COD和NH₃－N浓度分别为1000和25 mg/L，HRT为8 h时，MBBR的COD和TN去除率分别为92％和94％，而A/O工艺分别为78％和82％。造成这种结果的原因是MBBR的生物活性高，并且在生物膜内发生了同时硝化反硝化。MBBR脱氮能力受COD冲击明显小于A/O，但在较低进水COD浓度下，两者TN去除率均较低。     

A/O膜生物反应器处理高浓度氨氮废水试验研究

对A/O膜生物反应器处理高浓度氨氮废水进行了研究,着重考察硝化液回流比和C/N对系统脱氮效能的影响.研究表明,当硝化液回流比为2、C/N为6时.系统对COD、氨氮、TN的平均去除率分别达96.17%、97.76%、76.29%;A/O膜生物反应器稳定运行期间,氨氮容积负荷去除量与进水氨氮容积负荷呈现良好的线性关系;当A/O膜生物反应器内MLSS稳定在9～13 g/L时,上清液COD较低,膜压差增长缓慢.     

SUFR系统活性污泥特性及稳定性研究

通过实验考察了SUFR系统中活性污泥的特性及进水COD浓度、SRT和停运对稳定性的影响。结果表明：SUFR系统的污泥颗粒直径多在0.7～0.9 mm之间，属于小颗粒污泥，污泥沉降性能良好；对氮、磷有较好的去除效果。SUFR系统氮的去除对SRT有一定的耐冲击负荷，但受进水COD的影响较大；磷的去除对进水COD和SRT有较好的冲击能力；系统在经过72 h停运后污泥沉降性、脱氮与除磷效果都有较大降低，但基本在1周内就可恢复。     

不同C／N下人工湿地的脱氮效果及其强化措施

以人工湿地为研究对象，分析了不同C／N下人工湿地的脱氮效果。结果表明，C／N为10时，TN、NO2-N和COD平均去除率分别为（75．36±10．55）％、（86．34±9．23）％和（67．60±4．10）％，都显著高于其他2组系统（P=0．006、0．001、0〈0．01）；随着C／N的增加，NO3-N去除率呈现出上升的趋势；NH4-N刚好相反，C／N为1时，明显要高于其他2种情况（P=0〈0．05），平均去除率为（65．42-1-14．31）％。针对C／N为1时人工湿地脱氮效率较低（51．294-14．48）％的情况，对系统进水采取了添加一定量好氧反硝化细菌固定化小球并曝气12h的强化实验措施。结果发现，强化实验条件下TN、NOr-N和N03-N去除率均提高了10％以上，且都要明显高于非强化实验条件（P：0．003、0、0〈0．01），同时NH4-N和COD去除率没有明显差异，研究结果表明，从微生物角度对系统进水进行前处理有助于提高人工湿地脱氮效率。     

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.     

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.     

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 in deer and elk from Los Alamos national laboratory and the doses to humans from the ingestion of muscle and bone

Abstract

This paper summarizes radionuclide concentrations (³H, ⁹⁰Sr, ¹³⁷Cs, ²³⁸Pu, ^239,240Pu, ²⁴¹Am, and ^totU) in muscle and bone tissue of mule deer (Odocoileus hemionus) and Rocky Mountain elk (Cervus elaphus) collected from Los Alamos National Laboratory (LANL), Los Alamos, New Mexico, lands from 1991 through 1998. Also, the committed effective dose equivalent (CEDE) and the risk of excess cancer fatalities (RECF) to people who ingest muscle and bone from deer and elk collected from LANL lands were estimated. Most radionuclide concentrations in muscle and bone from individual deer (n = 11) and elk (n = 22) collected from LANL lands were either at less than detectable quantities (where the analytical result was smaller than two counting uncertainties) and/or within upper (95%) level background (BG) concentrations. As a group, most radionuclides in muscle and bone of deer and elk from LANL lands were not significantly higher (p<0.10) than in similar tissues from deer (n = 3) and elk (n = 7) collected from BG locations. Also, elk that had been radio collared and tracked for two years and spent an average time of 50% on LANL lands were not significantly different in most radionuclides from road kill elk that have been collected as part of the environmental surveillance program. Overall, the upper (95%) level net CEDEs (the CEDE plus two sigma for each radioisotope minus background) at the most conservative ingestion rate (50 lbs of muscle and 13 lbs of bone) were as follows: deer muscle = 0.22 mrem y^‐1 (2.2 μSv y^‐1), deer bone = 3.8 mrem y^‐1 (38 μSv y^‐1), elk muscle = 0.12 mrem y^‐1 (1.2 μSv y^‐1), and elk bone = 1.7 mrem y^‐1 (17 μSv y^‐1). All CEDEs were far below the International Commission on Radiological Protection guideline of 100 mrem y^‐1 (1000 μSv y^‐1), and the highest muscle plus bone net CEDE corresponded to a RECF of 2E‐06, which is far below the Environmental Protection Agency upper level guideline of 1E‐04.     

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.