新型分段进水脱氮反应器的去污性能研究

基于多段进水工艺原理,结合污泥自回流好氧生物脱氮反应器结构特征开发的新型分段进水脱氮反应器无需硝化液和污泥回流系统,大大简化了系统配置和操作难度。通过调整进水C/N和进水投配比初步研究了该反应器的去污性能。结果表明,新型分段进水脱氮反应器启动完成(21d)后,在进水COD质量浓度为155~455mg/L的条件下,平均出水COD为(39.6±7.3)mg/L,低于《城镇污水处理厂污染物排放标准》(GB 18918—2002)的一级A标准,且出水COD的变异系数为0.18,出水水质较为稳定;TN的去除主要受进水C/N的影响,NH+4-N的去除主要与最后一级的进水投配比有关。本实验的5种运行工况是以出水NH+4-N达标的前提下尽量去除TN为原则进行进水投配比设计的,在5种运行工况下,TN和NH+4-N去除性能良好,最高分别可达76%和89%。采用新型分段进水脱氮反应器处理浙江省实际生活污水(碱度与总凯氏氮平均比值为7.70)时基本无需调节碱度。     

进水碳氮比对SUFR系统脱氮除磷影响的特性分析

考察了进水碳氮比（C/N）对螺旋升流式反应器（spiral up-flow reactor，SUFR）系统生物脱氮除磷的影响，试验设计了进水C/N在7～13范围的数种工况，研究了SUFR系统中COD、总磷和氮的变化规律。结果表明，进水C/N对SUFR系统去除COD与TP效果的影响不明显，平均去除率分别为95.2%和93.9%；当进水C/N<9.4时，TN的去除率随C/N的增大而快速提高，而当进水C/N>9.4时，TN的去除率稳定在81.1%～85.6%；SUFR系统的硝化效果较稳定，氨氮的去除率保持在90.5%～98.8%；系统的反硝化作用随C/N的增大有所增强，出水硝酸盐氮浓度逐渐降低。     

A2/O+硫磺填料柱组合工艺脱氮除磷的效果

以某城市污水厂进水为研究对象,采用A2/O+硫磺填料反应柱组合工艺,考察其对COD、总氮、总磷以及溶解性磷处理效果的改善。组合工艺出水水质稳定后,连续运行55 d,并对工艺的出水进行常规指标分析。结果表明:组合工艺的脱氮除磷效果较单个A2/O工艺都得到了较大的改善,而COD去除效果变化不大。A2/O系统对COD有良好的去除效果,出水的COD平均去除率能达到94%;TN和TP去除效果相对较差,出水平均去除率分别为60%和57.4%。经硫磺填料反应柱的脱氮除磷作用,系统出水TN去除率提高到84%,TP去除率提高到69.8%,COD去除率变化不大,升高到95.3%。     

A~2/O＋硫磺填料柱组合工艺脱氮除磷的效果

以某城市污水厂进水为研究对象,采用A2/O＋硫磺填料反应柱组合工艺,考察其对COD、总氮、总磷以及溶解性磷处理效果的改善。组合工艺出水水质稳定后,连续运行55 d,并对工艺的出水进行常规指标分析。结果表明：组合工艺的脱氮除磷效果较单个A2/O工艺都得到了较大的改善,而COD去除效果变化不大。A2/O系统对COD有良好的去除效果,出水的COD平均去除率能达到94%;TN和TP去除效果相对较差,出水平均去除率分别为60%和57.4%。经硫磺填料反应柱的脱氮除磷作用,系统出水TN去除率提高到84%,TP去除率提高到69.8%,COD去除率变化不大,升高到95.3%。     

碳源类型及进水量分配对CMICAO工艺脱氮除磷的影响

研究了分别以葡萄糖和乙酸钠为碳源时多点交替进水阶式A2/O(CMICAO)工艺氮磷的去除效果,以及在不同进水C/N比时各进水量分配对脱氮除磷效果的影响.结果表明,在相同的进水COD浓度下,乙酸钠比葡萄糖更适合作为碳源,更能提高脱氮除磷效率.以葡萄糖为碳源时,COD为200 mg/L、C/N比为5、缺氧池与厌氧池进水配比为1∶2时,出水COD、TN、氨氮和TP浓度分别为28.5、10.8、2.1和0.5 mg/L,均达到国家一级A排放标准.若采用葡萄糖作为碳源,投加量以使进水C/N比为5～7.5为宜,外加碳源时缺氧池与厌氧池进水分配比可统一采用1∶1.     

混凝沉淀—UASB—MBR耦合工艺处理屠宰废水

为解决分散式小型屠宰厂在生产过程中产生的高浓度有机废水处理的问题,开展了物化单元(混凝沉淀)、生化单元(上流式厌氧污泥床反应器(UASB)工艺和膜生物反应器(MBR)工艺)对屠宰废水处理效果及影响因素的研究。结果表明:在混凝沉淀实验中,聚合氯化铝(PAC)最佳投加量为60mg/L、最佳pH范围为6.5~8.5;UASB工艺中,最佳进水上升流速为0.12m/h;MBR工艺中,最佳C/N(质量比)为5∶1~7∶1,DO在0.92~1.24mg/L时,对TN有较好处理效果,DO在1.24~1.68mg/L时,对COD及氨氮有较好处理效果。混凝沉淀—UASB—MBR耦合工艺连续运行的28d中,生化单元COD、TN和TP平均去除率分别为95.78%、89.17%、92.46%,出水水质良好。     

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%。     

高效垂直流人工湿地+多级生态塘深度处理污水厂尾水

采用高效垂直流人工湿地+多级生态塘组合工艺对污水厂尾水进行深度处理。研究发现,组合工艺进水流量为900 m3·d-1时为最优工况;在最优运行工况下组合工艺对污水处理厂尾水有显著的净化效果,对COD、NH3-N、TN和TP的去除效果可高达59.22%、81.06%、93.11%和55.81%,出水达到《地表水环境质量标准》(GB 3838-2002)Ⅳ类标准;生态塘能强化NH3-N和TN去除效果,可进一步除磷,降低富营养化风险;运行一年至少减少COD排放量9.85 t·a-1,NH3-N排放量1.73 t·a-1,TN排放量4.96 t·a-1,TP排放量0.16 t·a-1,具有良好的环境效益和经济效益。     

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。     

移动床生物膜反应器—膜生物反应器深度处理模拟废水及工业园区综合废水

将移动床生物膜反应器(MBBR)与膜生物反应器(MBR)有机结合,研究了该MBBR—MBR串联系统在水力停留时间(HRT)为17.50、11.75h条件下的脱碳脱氮的效果以及对工业园区综合废水污染物的去除情况。结果表明:(1)MBBR—MBR串联系统脱碳脱氮的效果良好,HRT的改变对系统的去除效果有一定的影响,随着总HRT由17.50h变为11.75h,模拟废水中COD的去除效果降低,但氨氮、硝态氮和TN的去除效果基本不受影响。(2)MBBR—MBR串联系统处理印染工业园区综合废水也有较好的效果,当进水COD、氨氮分别为150~450、20~40mg/L时,出水COD、氨氮平均分别为53.1、1.8mg/L,MBBR—MBR串联系统对COD、氨氮的去除率平均分别为80.4%、93.1%,但系统对TN的去除效果不是很理想。     

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.     

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 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.