水性聚氨酯(WPU)包埋活性污泥的亚硝化反应

以水性聚氨酯(WPU)为载体利用活性污泥制作成包埋固定化颗粒,置于序批式反应器(SBR)中在22.5~25.5℃、DO=2.0 mg·L~(-1)条件下,逐步提高进水氨氮浓度(100~200 mg·L~(-1))驯化13 d后包埋颗粒亚硝化率(NAR)成功实现至90.98%。运行30 d后NAR保持在95%以上,小试分析表明NOB活性受抑制,亚硝化处于稳定状态。然后调节曝气量,研究不同DO对亚硝化稳定性的影响。提高DO至4.5 mg·L~(-1),NAR仍保持在83.99%,说明活性污泥经包埋固定后对DO有较好的耐受性。通过扫描电镜(SEM)对反应器内包埋颗粒进行了微观分析。结果表明,包埋颗粒内接种污泥中细菌形态多样,含长杆、短杆及球状菌,随着运行的延续,细菌形态呈现了向短杆状球状转变的态势。     

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。     

基于曝气方式控制的碳捕获预处理黑水部分亚硝化工艺

短程硝化是短程生物脱氮工艺的前提与难点,通过曝气控制实现短程硝化具有操作灵活、成本低等优点.本文采用序批式活性污泥反应器,对比分析了高氧持续曝气、间歇曝气和低氧持续曝气3种曝气方式实现碳捕获预处理黑水短程硝化的效果和微生物群落结构的差异.结果表明:相对于高氧持续曝气和间歇曝气,低氧持续曝气工况亚硝态氮累积率(NAR)更...     

短程硝化在垃圾渗滤液处理工程中的应用

针对垃圾填埋场渗滤液生物脱氮高耗能的问题,通过对A/O/N工艺处理垃圾渗滤液进行短程硝化反硝化调试,对溶解氧(DO)、污泥浓度(MLSS)、污泥龄(SRT)、混合液回流比、pH、碱度进行定性定量分析,研究了不同条件下垃圾渗滤液生物处理阶段COD、氨氮及总氮去除效果,探讨了影响亚硝酸盐氮积累的因素。结果表明,好氧池低溶解氧能成功启动短程硝化,垃圾渗滤液稳定实现短程硝化反硝化脱氮。运行条件为:O反应器DO浓度0.5～0.8 mg·L~(-1),N反应器DO浓度1.5～2.2 mg·L~(-1),MLSS 3 500～4 500 mg·L~(-1),污泥龄9～13 d,混合液回流比1 100%,N反应器pH 7.6～8.2,N反应器碱度1.1 g·L~(-1)。短程硝化调试后,硝化阶段亚硝化率稳定在85%以上,COD、氨氮及总氮去除率分别达95%、98.6%、94.2%以上,节省30%碳源量和20%曝气量。     

低C/N比城市污水短程硝化特性及微生物种群分布

以城市污水厂二沉池回流液为接种污泥,研究了低C/N城市污水短程硝化特性及其微生物种群密度分布规律,并对比研究了SBR和SBBR 2种反应器短程硝化特性的差异。结果表明:在温度(30±1)℃、pH=7.9~8.2、DO=1.0 mg·L~(-1)的条件下,通过分段曝气的运行方式、经过29 d的运行,2个反应器均实现了短程硝化的高效启动,NH_4~+-N转化率稳定在99%,短程硝化率稳定在90%以上;相比于SBR,SBBR更有利于AOB菌种的富集,且SBBR达到亚硝酸盐积累率最大效果的时间快于SBR。利用聚合酶链反应(PCR)和克隆测序等分子生物学技术分析得出,在短程硝化稳定运行的SBR系统中,AOB菌种与NOB菌种的占比为2.3∶1。     

基于DO和游离氨联合控制的短程硝化快速启动及稳定运行研究

在高氨氮废水中,为了实现序批式活性污泥反应器(SBR)短程硝化的快速启动及稳定运行,采用DO与游离氨(FA)联合控制的策略进行调控。结果表明:控制DO为1.42～1.53mg/L,曝气时间为3.5h,将初始FA平均值从1.75mg/L提高至8.74mg/L,经过30d的运行,亚硝酸盐氮积累率达到75.71%,氨氮去除率稳定在80%左右,可以实现快速启动;进一步将DO提高至1.77～1.90mg/L,曝气时间降低至2.5h,可实现长达61d的稳定运行,氨氮平均去除率维持在85.70%,亚硝酸盐氮积累率平均达到91.80%。因此,FA和DO联合调控可抑制亚硝酸盐氧化菌活性,促进氨氧化菌增殖,可以实现短程硝化的快速启动及稳定运行。     

两级自养反硝化实现垃圾渗滤液的深度脱氮

针对目前生物工艺难以解决垃圾渗滤液深度脱氮的问题,探究了短程硝化反硝化-厌氧氨氧化-硫自养反硝化(两级自养)工艺处理高氨氮、低C/N比垃圾渗滤液的脱氮效果。结果表明,当进水垃圾渗滤液中氨氮平均浓度为2 560 mg·L~(-1),COD值为4 000～5 000 mg·L~(-1)时,经过短程硝化反硝化-厌氧氨氧化处理后,总氮去除负荷可达1.19 kg·(m~3·d)~(-1)、总氮去除率可达93.1%(出水TN=176.3 mg·L~(-1))、COD去除率可达52.2%。但是,厌氧氨氧化反应器出水中NO_x~--N浓度为154.5 mg·L~(-1),仍未达到我国生活垃圾填埋场垃圾渗滤液处理排放标准(TN≤40 mg·L~(-1))。在厌氧氨氧化反应器之后串联硫自养反硝化,整体工艺最终出水NH_4~+-N、NO_2~--N、NO_3~--N平均浓度分别为1.9、0.6、9.7 mg·L~(-1),TN≤15 mg·L~(-1),进水总氮去除率为99.5%。在短程硝化反硝化-厌氧氨氧化-硫自养反硝化两级自养深度脱氮反应系统中实现了垃圾渗滤液深度脱氮。     

基于DO控制实现SBR短程硝化过程

采用序批式反应器(SBR)处理模拟氨氮废水,研究了固定供氧模式下氨氮降解过程和溶解氧变化规律,并对DO控制实现短程硝化机理进行了探讨.实验结果表明,当DO＜1 mg/L时,体系产生亚硝酸盐积累,当亚硝化反应结束后,DO出现跃升现象,并且pH值对短程硝化有一定影响,充足的碱度和较高的pH值有利于建立以DO为控制参数实现短程硝化过程控制.短程硝化启动后,亚硝酸盐积累率达90％以上,并且经过度曝气5d后,系统仍保持稳定运行.     

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.     

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。     

Sources and fate of PCDD and PCDF

PCDD and PCDF were found in urban air particulates from St. Louis and Washington, D.C., and in sediments from the Great Lakes and Siskiwit Lake, Isle Royale. The similarity between the PCDD and PCDF found in air particulates and sediment samples and the presence of PCDD and PCDF in sediment from Siskiwit Lake (a location which can receive only atmospheric inputs) suggest that these compounds are emitted to the atmosphere from combustion sources. The historical input of PCDD and PCDF to dated sediment cores shows a strong increase since 1940, and this suggests that the incineration of chlorinated organic compounds is an important source of PCDD and PCDF to the environment.     

Meta-analysis of time-series studies of air pollution and mortality: effects of gases and particles and the influence of cause of death,age, and season

A comprehensive, systematic synthesis was conducted of daily time-series studies of air pollution and mortality from around the world. Estimates of effect sizes were extracted from 109 studies, from single- and multipollutant models, and by cause of death, age, and season. Random effects pooled estimates of excess all-cause mortality (single-pollutant models) associated with a change in pollutant concentration equal to the mean value among a representative group of cities were 2.0% (95% CI 1.5-2.4%) per 31.3 microg/m3 particulate matter (PM) of median diameter < or = 10 microm (PM10); 1.7% (1.2-2.2%) per 1.1 ppm CO; 2.8% (2.1-3.5%) per 24.0 ppb NO2; 1.6% (1.1-2.0%) per 31.2 ppb O3; and 0.9% (0.7-1.2%) per 9.4 ppb SO2 (daily maximum concentration for O3, daily average for others). Effect sizes were generally reduced in multipollutant models, but remained significantly different from zero for PM10 and SO2. Larger effect sizes were observed for respiratory mortality for all pollutants except O3. Heterogeneity among studies was partially accounted for by differences in variability of pollutant concentrations, and results were robust to alternative approaches to selecting estimates from the pool of available candidates. This synthesis leaves little doubt that acute air pollution exposure is a significant contributor to mortality.     

Meta-Analysis of Time-Series Studies of Air Pollution and Mortality: Effects of Gases and Particles and the Influence of Cause of Death,Age, and Season

Abstract

A comprehensive, systematic synthesis was conducted of daily time-series studies of air pollution and mortality from around the world. Estimates of effect sizes were extracted from 109 studies, from single- and multipollutant models, and by cause of death, age, and season. Random effects pooled estimates of excess all-cause mortality (single-pollutant models) associated with a change in pollutant concentration equal to the mean value among a representative group of cities were 2.0% (95% CI 1.5-2.4%) per 31.3 μg/m³ particulate matter (PM) of median diameter <10 μm (PM₁₀); 1.7% (1.2-2.2%) per 1.1 ppm CO; 2.8% (2.1-3.5%) per 24.0 ppb NO₂; 1.6% (1.1-2.0%) per 31.2 ppb O₃; and 0.9% (0.7-1.2%) per 9.4 ppb SO₂ (daily maximum concentration for O₃, daily average for others). Effect sizes were generally reduced in multipollutant models, but remained significantly different from zero for PM₁₀ and SO₂. Larger effect sizes were observed for respiratory mortality for all pollutants except O₃. Heterogeneity among studies was partially accounted for by differences in variability of pollutant concentrations, and results were robust to alternative approaches to selecting estimates from the pool of available candidates. This synthesis leaves little doubt that acute air pollution exposure is a significant contributor to mortality.     

Field and laboratory studies of the fate and enantiomeric enrichment of venlafaxine and O-desmethylvenlafaxine under aerobic and anaerobic conditions

The stereoselectivity of R,S-venlafaxine and its metabolites R,S-O-desmethylvenlafaxine, N-desmethylvenlafaxine, O,N-didesmethylvenlafaxine, N,N-didesmethylvenlafaxine and tridesmethylvenlafaxine was studied in three processes: (i) anaerobic and aerobic laboratory scale tests; (ii) six wastewater treatment plants (WWTPs) operating under different conditions; and (iii) a variety of wastewater treatments including conventional activated sludge, natural attenuation along a receiving river stream and storage in operational and seasonal reservoirs. In the laboratory and field studies, the degradation of the venlafaxine yielded O-desmethylvenalfaxine as the dominant metabolite under aerobic and anaerobic conditions. Venlafaxine was almost exclusively converted to O-desmethylvenlafaxine under anaerobic conditions, but only a fraction of the drug was transformed to O-desmethylvenlafaxine under aerobic conditions. Degradation of venlafaxine involved only small stereoisomeric selectivity. In contrast, the degradation of O-desmethylvenlafaxine yielded remarkable S to R enrichment under aerobic conditions but none under anaerobic conditions. Determination of venlafaxine and its metabolites in the WWTPs agreed well with the stereoselectivity observed in the laboratory studies. Our results suggest that the levels of the drug and its metabolites and the stereoisomeric enrichment of the metabolite and its parent drug can be used for source tracking and for discrimination between domestic and nondomestic wastewater pollution. This was indeed demonstrated in the investigations carried out at the Jerusalem WWTP.     

Sorption and desorption of Cu and Cd by macroalgae and microalgae

The sorption and desorption of Cu and Cd by two species of brown macroalgae and five species of microalgae were studied. The two brown macroalgae, Laminaria japonica and Sargassum kjellmanianum, were found to have high capacities at pHs between 4.0 and 5.0 while for microalgae, optimum pH lay at 6.7. The presence of other cations in solution was found to reduce the sorption of the target cation, suggesting a competition for sorption sites on organisms. Sorption isotherms obeyed the Freundlich equation, suggesting involvement of a multiplicity of mechanisms and sorption sites. For the microalgae tested, Spirulina platensis had the highest capacity for Cd, followed by Nannochloropsis oculata, Phaeodactylum tricornutum, Platymonas cordifolia and Chaetoceros minutissimus. The reversibility of metal sorption by macroalgae was examined and the results show that both HCl and EDTA solutions were very effective in desorbing sorbed metal ions from macroalgae, with up to 99.5% of metals being recovered. The regenerated biomass showed undiminished sorption performance for the two metals studied, suggesting the potential of such material for use in water and wastewater treatment.     

Sources and distribution of polychlorinated-dibenzo-p-dioxins and -dibenzofurans in soil and sediment from the Yellow Sea region of China and Korea

Polychlorinated-dibenzo-p-dioxins and -dibenzofurans (PCDD/Fs) were measured in soils and sediments from the Yellow Sea region. Korean soils and sediments mostly contained detectable PCDD/Fs and showed a widespread distribution among locations. Soil and sedimentary PCDD/Fs from China were comparable to or less than those in Korea. The patterns of relative concentrations of individual congeners in soils were different between the two countries, but similar in sediments. Sources of PCDD/Fs in China and Korea were found to be independent of each other and their distributions reflected matrix-dependent accumulation. Spatial distribution indicated some point sources in Korea while Chinese sources were more widespread and diffuse. PCDD/Fs measured in the coastal areas of the Yellow Sea were comparable to or less than those previously reported in for eastern Asia. However, ∑TEQs in soils and sediments were near to or, in some cases exceeded environmental quality guidelines.     

剩余污泥浓缩脱水投药量优化和模型建立

应用高分子阳离子絮凝剂（CPF-100）和聚丙烯酰胺（PAM）对污水厂剩余污泥进行浓缩脱水实验，研究表明：CPF-100的浓缩脱水效果优于PAM；当CPF-00投加量为1．16‰时，污泥沉降性能改善程度为37．51％；且在CPF-100投加量逐渐增大的初始阶段，污泥沉降性能改善程度随投加量的增加而增大，但CPF-100投加量也不宜过大，当CPF-100投加量超过1．16‰后，反而会使浓缩脱水效果变差。同时，建立了污泥沉降性能改善程度与絮凝剂CPF-100投加量、沉降时间之间的数学模型，其能较好地反映污水厂剩余污泥的浓缩脱水效果。     

骆马湖富营养化和生态状况调查与评价

为了了解骆马湖水质状况，在2005年对骆马湖富营养化状态和生态特性进行了调查，并结合“十五”期间的监测资料进行了分析。2005年骆马湖水体中总氮和总磷的平均值超《地表水环境质量标准》（GB3838-2002）中Ⅲ类，超标情况分别为0．78倍和0．54倍，达到湖库特定项目Ⅳ类水标准，骆马湖处于轻度富营养化状态。对骆马湖生态特征分析表明，由于该湖泊的形态以及“藻型浊水状态”和“泥沙型浊水状态”交替出现，遏制了湖水从高营养盐含量向全面富营养化状态演变，保障了底栖动物的良好生长环境，从而形成了骆马湖独特的环境生态平衡。     

Spatial and temporal trend of Chinese manure nutrient pollution and assimilation capacity of cropland and grassland

Dynamics of livestock and poultry manure nutrient was analyzed at a provincial scale from 2002 to 2008. The nutrient capacity of 18 kinds of croplands and grasslands to assimilate nutrients was assessed in the same temporal–spatial scale. Manure nitrogen (N) had increased from 5.111 to 6.228 million tons (MT), while manure phosphorus (P) increased from 1.382 to 1.607 MT. Manure N and P share similar spatial patterns of yields, but proportion of specialized livestock husbandry and contribution of leading livestock categories (swine, cattle, cow, sheep, layer chicken, broiler chicken) were different. The nutrients generated from dominant seven provinces took more than about half of total manure N in China. After subtracting the chemical fertilizers, there were some manure nutrient capacities in western part of China. Risk analysis of manure nutrient pollution overload in eastern and southern parts of China was serious, which should restrict livestock's developments. Amount of chemical fertilizers applied should be reduced to make room for manure nutrients. For the sake of greenhouse effects, the emission of methane (CH₄) and nitrous oxide (NO _x ) emissions in China is serious for the global change, thus merits further statistics and studies. The spatial and temporal pattern of Chinese manure nutrient pollution from livestock and the assimilation capacity of cropland and grassland can provide useful information for policy development on Chinese soil environment and livestock.