三种反硝化滤池深度脱氮中试

以污水厂实际二级出水为处理目标,通过中试试验研究了陶粒滤料反硝化生物滤池、固定床反硝化砂滤池和连续过滤连续反冲砂滤池的特性。以甲醇作为外加碳源,3种滤池均可实现出水平均总氮小于5 mg/L。不足量投加外碳源会出现出水亚硝态氮的积累。当进水TN为15 mg/L左右时,为达到出水TN小于5 mg/L,生物滤池、固定床砂滤池和连续过滤砂滤池建议滤速分别为不大于8,5.2,6.2 m/h;滤池反硝化碳源投加比例分别为4.28,3.0,3.2 g甲醇/gTN;对应的反硝化容积负荷平均值分别为1.1,0.8,1.2 kg/(m3·d)。进水组分分析发现,有机氮不是出水总氮小于5 mg/L的限制因素。     

一体化多级生物膜反应器处理高氮小城镇污水脱氮试验研究

采用新型一体化多级生物膜反应器处理高氮小城镇污水,在反应器中实现了高效的同步硝化反硝化脱氮,同时采用多点进水方式解决了脱氮低碳源问题.试验结果表明,在温度20℃,有机负荷(COD)为0.85 kg·m-3·d-1、氮负荷为0.27 kg·m-3·d-1、HRT为9h、分点进水条件下,可使进水COD为320 mg.L-1,TN为97 mg.L-1,NH;.N为84mg·L-1左右的高氮城镇污水,出水COD、TN、NH4 -N分别为16 mg·L-1、19.1mg·L-1、6.86 mg·L-1,达到国家一级排放B标准.     

SBBR同步硝化反硝化处理生活污水的影响因素

序批式生物膜反应器SBBR采用塑料鲍尔环填料,在有氧情况下用于处理实际生活污水.该反应器能很好地创造缺氧微环境,载体生物膜具有吸附储碳能力,出现了良好的同步硝化和反硝化现象.反应器中溶解氧浓度在较大的范围内(0.8～4.0 mg·L-1)能有效地实现同步硝化和反硝化.当溶解氧浓度大于4.0 mg·L-1后,TN容积去除率大幅下降,出水TN大幅上升.增加载体生物膜厚度有利于同步硝化和反硝化.进水浓度基本不影响脱氮的效率,但出水TN随进水浓度增加而升高,建议原水浓度高时可增加后续脱氮处理或减少进水量来满足出水要求.优化运行方法和参数后,SBBR连续运行的TN去除率可稳定在74%～82%.     

生物可降解聚合物在微污染水体中固相反硝化脱氮效果研究

为解决微污染水体因低碳氮比而导致脱氮效率差的问题,本文选择聚丁二酸丁二醇酯(PBS)、聚ε-己内酯(PCL)和聚乳酸(PLA)3种生物可降解聚合物,对比其作为填充床反应器的膜载体与反硝化固相碳源的反硝化效果。结果表明:在进水TN质量浓度维持在1 4.31~1 9.21 mg/L,HRT为1.0 h时,PBS填充床的TN平均去除率为94.95%,优于PC L.的84.46%,PLA未能维持良好去除率;PBS与PCL.填充床的平均反硝化速率(以NO_3-N计)分别为1 2.1 4、1 0.11 mg/(L·h),二者出水溶解性有机碳(DOC)先上升后降低至1.3 mg/L,表明二者可被微生物降解,是良好的反硝化固相碳源;PBS与PCL.填充床出水NO_2-N浓度0.1 0 mg/L,NH_3-N浓度0.45 mg/L,出水效果良好,不会造成二次污染;3种固体碳源反应前后质量下降不明显,表明其化学结构未发生显著变化;电子扫描显微镜(SEM)扫描显示PBS和PCL反应表面空隙率较高,反应后被腐蚀痕迹明显,表明二者适合作为生物膜载体供微生物附着生长,PLA表面变化不明显。     

腐朽木为填料的反硝化滤池特性研究

针对城市污水处理厂二级出水低碳氮比的水质特点,该文通过腐朽木的释碳静态实验和反硝化滤池动态实验,研究了腐朽木的碳源释放规律,对腐朽木释碳组份进行了GC/MS分析,同时以人工模拟配制低碳氮比废水作为反硝化滤池实验的进水,从TN、NO_3~--N的去除效果和COD、NO_2~--N、NH_3-N的变化规律,分析和研究腐朽木作为填料在不同水力停留时间(HRT)下反硝化滤池的脱氮性能和运行效果。结果表明,腐朽木可有效地释放碳源物质,腐朽木释碳组份主要为(Z)-9-Octadecenamide,其分子式为C18H35NO;反硝化滤池在初始阶段HRT为12 h时,脱氮效果最佳,TN、NO3--N去除率最高分别可达到94.41%、97.13%,此时腐朽木作为外加缓释碳源填料显著提高了滤池脱氮效果。     

生物膜脱氮滤池的微生物群落结构特性

为探究生物膜脱氮滤池脱氮效能差异的微生物因素,设置组1(包括接种污泥、稳定期滤料、反冲洗后滤料微生物变化)和组2(包括反冲洗前滤料、反冲洗后不同时间段滤料微生物变化)两组实验,通过高通量测序,研究不同阶段微生物群落结构、丰度和多样性的分布情况.结果表明:接种污泥与滤料表面微生物群落结构和多样性在门水平下差异不大,但在属水平下差异显著,而相对丰度在两种分类水平下始终差异显著.反冲洗后0～4 h滤料表面微生物的OTU数目、Shannon指数、Chao1指数变化,在滤池30 cm处先升后降,而在60 cm处曲折上升,也即二者的微生物丰度和多样性变化趋势.反冲洗前后Proteobacteria始终占主导地位,相对丰度为79%～90%,Proteobacteria中Betaproteobacteria占主导优势,反冲洗后Betaproteobacteria数量相对减少,后逐渐恢复.总反硝化优势菌属相对丰度在反冲洗1 h后30 cm处由78%左右下降到70%左右,60 cm处由68%左右下降到64%左右,此时出水总氮达到最高值7.7 mg·L~(-1),之后总反硝化优势菌属及出水TN浓度逐渐恢复至正常水平,这种消长变化表明滤池脱氮效果与总反硝化优势菌属相对丰度密切相关,滤池运行状态的改变使得反硝化优势菌属的群落结构差异显著.     

高氮渗滤液短程深度脱氮及反硝化动力学

采用单级UASB-SBR生化系统处理实际高氮晚期渗滤液,重点研究了系统的有机物和氮去除特性,同时考察了SBR短程生物脱氮系统内微生物的反硝化动力学特性.试验结果表明,该生化系统能够高效、深度去除渗滤液内高浓度有机物和氮.UASB反应器的平均COD负荷为6.5 kg/(m3.d),去除速率为5.3 kg/(m3.d).在进水COD平均为6 537 mg.L-1,NH+4-N为2 021mg.L-1的条件下,出水分别为354 mg.L-1和2.8 mg.L-1以下,去除率分别为94.6%和99.8%,尤其是该系统获得了99.2%的TN去除率,出水TN20 mg.L-1,实现了深度脱氮的目的.SBR反应器实现并维持了稳定的短程硝化,通过90%以上的亚硝化率实现高效的氨氮去除,同时SBR系统内微生物的反硝化特性符合Monod动力学方程.     

基于SBR-ABR实现PN-SAD耦合工艺的运行与优化调控

采用序批式活性污泥反应器-厌氧折流板反应器(SBR-ABR)组合工艺,构建"部分亚硝化-厌氧氨氧化反硝化"(PNSAD)反应链实现深度脱氮除碳.设定3种不同的运行工况,工况Ⅰ将SBR出水(NO_2~--N/NH_4~+-N为1～1.32)直接接入单隔室ABR厌氧氨氧化系统,发现虽然实现了厌氧氨氧化反应的稳定运行,但联合工艺总氮(TN)去除率低于80%,出水TN约20mg·L~(-1).为在ABR内增加反硝化功能,向ABR反应器第三隔室添加反硝化污泥,于工况Ⅱ将SBR出水接入,发现耦合反应对TN去除率仍偏低若实现深度脱氮需在厌氧氨氧化后段补充碳源.故在工况Ⅲ调控SBR出水(NO_2~--N/NH_4~+-N=5)与部分原水混合(NO_2~--N/NH_4~+-N=1.4;C/N=2.5),接入单隔室ABR厌氧氨氧化反硝化系统不仅实现了厌氧氨氧化段基质的良好配比,也为反硝化提供了良好的有机碳源,整个工艺出水COD为50左右,TN在6以下,TN去除率达到95%.在SBR-ABR反应器内构建PN-SAD联合反应为废水深度脱氮除碳提供了理论基础.     

基于短程反硝化厌氧氨氧化的低碳源城市污水深度脱氮特性

短程反硝化厌氧氨氧化是一种新型生物脱氮技术,应用于城市污水深度脱氮有望大幅降低外碳源投加量.本研究接种厌氧氨氧化污泥,考察了短程反硝化厌氧氨氧化的深度脱氮性能与污泥特性.结果表明,接种厌氧氨氧化污泥可迅速启动短程反硝化厌氧氨氧化系统,在进水COD/TN为2.19±0.08时,出水TN浓度为(4.82±1.84)mg·L~(-1),实现了低碳源污水深度脱氮.系统粒径大于0.20 mm的污泥占86.16%,污泥实现了颗粒化,有助于厌氧氨氧化菌在系统内的有效持留.将短程反硝化厌氧氨氧化深度脱氮应用于城市污水处理厂二沉池出水深度脱氮,可降低外碳源投加量,同时可降低污水处理厂硝化池耗氧量.     

以PHAs为固体碳源的城镇二级出水深度脱氮研究

利用从连续运行的缓释碳源滤料滤池中取出的聚羟基脂肪酸酯(PHAs)颗粒,研究了微生物和硝酸盐对其的总有机碳(TOC)释放速率的影响,并研究了温度、pH值、硝态氮浓度对其反硝化速率的影响.结果表明:原有的和附着有微生物的PHAs颗粒在去离子水中TOC释放速率分别为0.030,0.053mg/(g·d),远低于水中有硝酸盐时的TOC释放速率[进水NO3--N为30mg/L时,TOC释放速率为0.533mg/(g·d)].温度和pH值对反硝化速率影响较大, pH值为7.5时,在15~35℃范围内, 30℃下的反硝化速率最大,为0.067mg/(g·h);温度为30℃时,pH值在6.0~9.0范围内,pH值为7.8时的反硝化速率最大,达到0.061mg/(g·h).反硝化速率与NO3--N浓度之间的关系符合Monod方程,最大反应速率和半饱和常数分别为4.74mgNO3--N/(gSS·h)和56.6mg/L.     

Effects of two sludge application on fractionation and phytotoxicity of zinc and copper in the soil

The potential harm of heavy metals is a primary concern in application of sludge to the agricultural land. A pot experiment was conducted to evaluate the effect of two sludges on fractionation of Zn and Cu in soil and their phytotoxicity to pakchoi. The loamy soil was mixed with 0%, 20%, 40%, 60% and 80% (by weight) of digested sewage sludge (SS) and composted sludge (SC). The additions of both sludges caused a significant raise in all fractions, resulting in that exchangeable (EXCH) and organic bound (OM) became predominance of Zn and organic bound Cu occupied the largest portion. There was more available amount of Zn and Cu in SS treatments than SC treatments. During the pot experiment, the concentration of Zn in EXCH, carbonate (CAR) and OM and Cu in EXCH and OM fractions decreased in all treatments, so their bioavailability reduced. Germination rate and plant biomass decreased when the addition rate was high and the best yield appeared in 20% mixtures at the harvest of pakchoi. The two sludges increased tissue contents of Zn and Cu especially in the SS treatments. Zn in pakchoi was not only in relationship to ΔEXCH and ΔCAR forms but also in ΔOM forms in the sludge-soil mixtures. Tissue content of Cu in pakchoi grown on SC-soils could not be predicted by ΔEXCH. These correlation rates between Zn and Cu accumulation in pakchoi and variation of different fractions increased with time, which might indicate that sludges represented stronger impacts on the plant in long-term land application.     

Intraspecific differences in effects of co-contamination of cadmium and

A hydroponic experiment was carried out to study intraspecific differences in the effects of different concentrations of cadmium (Cd)(0-10 mg/L) and arsenate (As(V)) (0-8 mg/L) on the growth parameters and accumulation of Cd and As in six wheat varieties Jing-9428, Duokang-1, Jingdong-11, Jing-411, Jingdong-8 and Zhongmai-8. The endpoints of wheat seedlings, including seed germination,biomass, root length and shoot height, decreased with increasing the Cd and As concentrations. Significant differences in seed germination, biomass, root length, shoot height and the accumulation of Cd and As were observed between the treatments and among the varieties (p ＜ 0.05). The lethal dosage 50% were about 20, 80, 60, 60, 80 and 20 mg As/L for Jing-9428, Duokang-1, Jingdong-11,Jing-411, Jingdong-8 and Zhongmai-8, respectively, and the corresponding values for Cd were about 30, 80, 20, 40, 60 and 10 mg Cd/L, respectively. Among the six varieties, Duokang-1 was found to be the most resistant to Cd and As toxicity, and Zhongmai-8 was the most sensitive to Cd and As co-contamination. The resistance of the six varieties was found dependant on the seedling uptake of Cd and As. Duokang-1 was the most suitable for cultivation in Cd and As co-contaminated soils.     

Toxic effects of acetochlor, methamidophos and their combination on nifH gene in soil

Toxic effects of two agrochemicals on nifH gene in agricultural black soil were investigated using denaturing gradient gel electrophoresis （DGGE） and sequencing approaches in a microcosm experiment. Changes of soil nifH gene diversity and composition were examined following the application of acetochlor, methamidophos and their combination. Acetochlor reduced the nifH gene diversity （both in gene richness and diversity index values） and caused changes in the nifH gene composition. The effects of acetochlor on nifH gene were strengthened as the concentration of acetochlor increased. Cluster analysis of DGGE banding patterns showed that nifH gene composition which had been affected by low concentration of acetochlor （50 mg/kg） recovered firstly. Methamidophos reduced nifH gene richness that except at 4 weeks. The medium concentration of methamidophos （150 mg/kg） caused the most apparent changes in nifH gene diversity at the first week while the high concentration of methamidophos （250 mg/kg） produced prominent effects on nifH gene diversity in the following weeks. Cluster analysis showed that minimal changes of nifH gene composition were found at 1 week and maximal changes at 4 weeks. Toxic effects of acetochlor and methamidophos combination on nifH gene were also apparent. Different nifH genes （bands） responded differently to the impact of agrochemicals： four individual bands were eliminated by the application of the agrochemicals, five bands became predominant by the stimulation of the agrochemicals, and four bands showed strong resistance to the influence of the agrochemicals. Fifteen prominent bands were partially sequenced, yielding 15 different nifH sequences, which were used for phylogenetic reconstructions. All sequences were affiliated with the alpha- and beta-proteobacteria, showing higher similarity to eight different diazotrophic genera.     

Arsenic uptake by arbuscular mycorrhizal maize （Zea mays L.） grown in an arsenic-contaminated soil with added phosphorus

The effects of arbuscular mycorrhizal (AM) fungus (Glomus mosseae) and phosphorus (P) addition (100 mg/kg soil) on arsenic (As) uptake by maize plants (Zea mays L.) from an As-contaminated soil were examined in a glasshouse experiment.Non-mycorrhizal and zero-P addition controls were included.Plant biomass and concentrations and uptake of As,P,and other nutrients,AM colonization,root lengths,and hyphal length densities were determined.The results indicated that addition of P significantly inhibited root colonization and development of extraradical mycelium.Root length and dry weight both increased markedly with mycorrhizal colonization under the zero-P treatments,but shoot and root biomass of AM plants was depressed by P application.AM fungal inoculation decreased shoot As concentrations when no P was added,and shoot and root As concentrations of AM plants increased 2.6 and 1.4 times with P addition,respectively.Shoot and root uptake of P,Mn,Cu,and Zn increased,but shoot Fe uptake decreased by 44.6%,with inoculation, when P was added.P addition reduced shoot P,Fe,Mn,Cu,and Zn uptake of AM plants,but increased root Fe and Mn uptake of the nonmycorrhizal ones.AM colonization therefore appeared to enhance plant tolerance to As in low P soil,and have some potential for the phytostabilization of As-contaminated soil,however,P application may introduce additional environmental risk by increasing soil As mobility.     

Degradation of metabolites accumulated of benzo[a]pyrene by coupling Penicillium Chrysogenum with KMnO4

Several main metabolites of benzo[a]pyrene （BaP） formed by Penicillium chrysogenum, Benzo[a]pyrene-1,6-quinone （BP 1,6- quinone）, trans-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene （BP 7,8-diol）, 3-hydroxybenzo[a]pyrene （3-OHBP）, were identified by high-performance liquid chromatography （HPLC）. The three metabolites were liable to be accumulated and were hardly further metabolized because of their toxicity to microorganisms. However, their further degradation was essential for the complete degradation of BaP. To enhance their degradation, two methods, degradation by coupling Penicillium chrysogenum with KMnO4 and degradation only by Penicillium chrysogenum, were compared; Meanwhile, the parameters of degradation in the superior method were optimized. The results showed that （1） the method of coupling Penicillium chrysogenum with KMnO4 was better and was the first method to be used in the degradation of BaP and its metabolites; （2） the metabolite, BP 1,6-quinone was the most liable to be accumulated in pure cultures; （3） the effect of degradation was the best when the concentration of KMnO4 in the cultures was 0.01% （w/v）, concentration of the three compounds was 5 mg/L and pH was 6.2. Based on the experimental results, a novel concept with regard to the bioremediation of BaP-contaminated environment was discussed, considering the influence on environmental toxicity of the accumulated metabolites.     

Impact of atrazine and nitrogen fertilizers on the sorption of chlorotoluron in soil and model sorbents

Sorption of chlorotoluron in ammonium sulfate, urea and atrazine multi-solutes system was investigated by batch experiments. The results showed application of nitrogen fertilizers to the soil could affect the behavior of chlorotoluron. At the same concentration of N, sorption of chlorotoluron decreased as the concentration of atrazine increased on the day 0 and 6 in soil, respectively. The sorption of chlorotoluron increased from 0 to 6 d when soils were preincubated with deionized water, ammonium sulfate and urea solution for 6 d. That indicated incubation time was one of the most important factors for the sorption of chlorotoluron in nitrogen fertilizers treatments. The individual sorption isotherms of chlorotoluron in rubbery polymer and silica were strictly linear in single solute system, but there were competition sorption between pesticides or between pesticides and nitrogen fertilizers. That indicated the sorption taken place by concurrent solid-phase dissolution mechanism and sorption on the interface of water-organic matter or water-mineral matter.     

Distribution and ecological effect of mercury in Laogang landfill, Shanghai, China

Laogang landfill near Shanghai is the largest landfill in China, and receives about 10000 t of daily garbage per day, Samples of topsoil and plants were analyzed to evaluate mercury pollution from the landfill. For topsoil samples, there were significant correlations among total mercury （HgT）, combinative mercury （Hgc） and gaseous mercury （HgG）, and content of total organic carbon （TOC）, but, no significantly relationship was found between Hg content and filling time. Hg content changes in vertical profiles with time showed that the average Hgv of profiles 1992, 1996, and 2000 was similar, but their average HgG was quite different. HgT was significantly correlated with Hgc in profile 1992 and 2000, and Hgv was significantly correlated with Hg6 in profile 1996. HgG/Hgv ratio in profile samples decreased in the order of （HgG,/HgT）1992〉（HgG/HgT）1996〉〉（HgG/HgT）2000. A simple outline of Hg release in landfill could be drawn： with increasing of filling time, degradation undergoes different biodegradation, accordingly, gaseous mercury goes through small, more, and small proportion to total mercury. Distribution of Hg in plants was inhomogeneous, following the order of leaf〉root〉stem. The highest value of leaf may be associated with higher atmospheric Hg from landfill. Ligneous plants （e.g. Phyllostachys glanca, Prunus salicina and Ligustrum lucidum） are capable of enriching more Hg than herbaceous plants.     

EDTA-enhanced phytoremediation of lead contaminated soil by Bidens maximowicziana

Phytoremediation is a potential cleanup technology for the removal of heavy metals from contaminated soils.Bidens maximowicziana is a new Pb hyperaccumulator,which not only has remarkable tolerance to Pb but also extraordinary accumulation capacity for Pb.The maximum Pb concentration was 1509.3 mg/kg in roots and 2164.7 mg/kg in overground tissues.The Pb distribution order in the B. maximowicziana was:leaf>stem>root.The effect of amendments on phytoremediation was also studied.The mobility of soil Pb and the Pb concentrations in plants were both increased by EDTA application.Compared with CK(control check),EDTA application promoted translocation of Pb to overground parts of the plant.The Pb concentrations in overground parts of plants was increased from 24.23-680.56 mg/kg to 29.07-1905.57 mg/kg.This research demonstrated that B.maximowicziana appeared to be suitable for phytoremediation of Pb contaminated soil,especially,combination with EDTA.     

Decomposition of alachlor by ozonation and its mechanism

Decomposition and corresponding mechanism of alachlor, an endocrine disruptor in water by ozonation were investigated. Results showed that alachlor could not be completely mineralized by ozone alone. Many intermediates and final products were formed during the process, including aromatic compounds, aliphatic carboxylic acids, and inorganic ions. In evoluting these products, some of them with weak polarity were qualitatively identified by GC-MS. The information of inorganic ions suggested that the dechlorination was the first and the fastest step in the ozonation of alachlor.     

Enzymatic oxidation of aqueous pentachlorophenol

The influence of the nonionic surfactant Tween 80 on pentachlorophenol （PCP） oxidation catalyzed by horseradish peroxidase was studied. The surfactant was tested at concentrations below and above its critical micelle concentration （CMC）. Enhancement of PCP removal was observed at sub-CMCs. The presence of Tween 80 in the reaction mixture reduced enzyme inactivation which occurred through a combination of free radical attack and sorption by precipitated products. A simple first-order model was able to simulate time profiles for enzyme inactivation in the presence or absence of Tween 80. At supra-CMCs, the surfactant caused noticeable reductions in PCP removal, presumably through micelle partitioning of PCP which precluded the hydrophobic PCP molecule from interacting with the enzyme.