基于厌氧氨氧化的城镇生活污水深度脱氮工艺研究

随着城镇生活污水排放标准的日益严格,现有城市污水处理厂普遍面临提标改造的挑战,较多污水处理厂采用三级脱氮工艺降低出水中氮素含量.本研究以磁混凝预处理后的生活污水为研究对象,采用厌氧氨氧化工艺作为三级脱氮工艺,构建含有生物膜和絮体污泥的UASB反应器,处理A/O（二级生化单元）出水,研究串联、分流进水以及回流等条件下系统的脱氮及有机物去除性能,并通过微生物群落分析揭示各阶段的菌群结构变化.结果表明,当UASB串联A/O时,系统出水氨氮、TN和COD分别为1.21、10.02和30.00 mg·L^-1.当进水分流比为15%时,提升了UASB的脱氮速率（从0.04升高至0.06 kg·m^-3·d^-1）,UASB分别贡献了系统TN、NH₄⁺-N和COD去除总量的23.4%、20%和20.7%,当系统出水回流到A区时,能进一步降低出水污染物浓度,NH₄⁺-N仅为1 mg·L^-1,TN为12.03 mg·L^-1.微生物群落结构分析结果表明,在A/O反应器内Proteobacteria为主要菌门,UASB内Planctomycetes门实现富集,生物膜中Planctomycetes丰度为1.93%~8.39%,厌氧氨氧化细菌（以Candidatus Kuenenia为代表）在生物膜和污泥絮体中丰度分别为0.77%~2.19%和0.01%~1.49%.本研究结果表明,基于厌氧氨氧化的三级脱氮工艺能够实现生活污水的深度脱氮,在不增加曝气与碳源投加成本的同时高效去除氨氮、总氮,可为城市生活污水处理厂改造升级提供技术支撑.     

不同形态厌氧氨氧化菌处理磁分离出水脱氮性能及微生物群落结构变化分析

采用两种不同形态（固定生物膜和颗粒态）的厌氧氨氧化菌（AnAOB）,考察了其对磁分离出水的脱氮性能、氮负荷的差异,同时从分子生物学的角度分析了微生物群落结构的变化.结果表明：采用自模拟污水,35℃恒温、不同水力停留时间（HRT）条件下,两个反应器对NH₄⁺-N和NO₂^--N的去除率均大于90%.此外,反应器内的微生物群落结构也发生改变,固定生物膜和颗粒反应器中Candidatus Kuenenia菌属消失,Candidatus_Brocadia、Candidatus_Jettenia成为体系厌氧氨氧化优势菌属,相对丰度分别上升至0.89%、0.63%（固定生物膜）和8.79%、2.92%（颗粒）.采用磁分离出水,随着HRT的降低,两种形态的厌氧氨氧化菌对NH₄⁺-N和NO₂^--N去除率均在80%以上.反应器中厌氧氨氧化菌Candidatus_Brocadia、Candidatus_Jettenia的相对丰度明显下降,最终稳定维持在0.7%左右,并伴随异养菌的出现.     

MnO2强化厌氧氨氧化工艺启动及其微生物机理研究

通过对照试验考察了添加MnO₂对厌氧氨氧化污泥驯化和培养的影响,并采用16S rRNA基因高通量测序技术和定量PCR分析其机理.结果表明,添加MnO₂粉末能够显著提高容积氮负荷及运行性能,其脱氮速率高达848.04 mg·L^-1·d^-1,几乎是对照组反应器的2倍.16S rRNA基因高通量测序技术和定量PCR结果表明,添加MnO₂粉末促进了典型厌氧氨氧化菌Candidate Brocadia的富集,厌氧氨氧化菌16S rRNA基因和功能基因hzsB的丰度显著提高.     

长期饥饿下厌氧氨氧化反应器的启动与恢复性能

厌氧氨氧化菌生长缓慢,其富集过程困难,是限制厌氧氨氧化技术应用的瓶颈. 因基质供应不足导致的功能菌长期饥饿使厌氧氨氧化（ANAMMOX）反应器稳定运行面临更大挑战. 从长期饥饿的视角出发,重新审视厌氧氨氧化反应器的启动和恢复性能、揭示其抗性机制具有现实意义. 分别采用硝化和反硝化污泥在不同运行条件下成功启动了厌氧氨氧化反应器,分析了长期饥饿后不同启动策略下反应器的恢复性能,及污泥对长期饥饿的耐受机制. 结果表明,接种反硝化污泥的反应器采用高基质浓度低流速运行更稳定,运行85 d后NH₄⁺-N、NO₂^--N和总氮去除率分别高达98.7%、99.3%和89.3%;但长期饥饿（144 d）后采用低基质浓度高流速运行的氮去除性能更优,NH₄⁺-N、NO₂^--N和总氮去除率可在30 d后分别恢复至99.8%、99.8%和93.6%. 研究发现,饥饿期胞外多聚物将厌氧氨氧化菌包裹,有助于保持细胞完整以抵抗长期饥饿胁迫;nirS、hzsA和hdh基因的表达,保证了亚硝酸盐/一氧化氮氧化还原酶、联氨合成酶和联氨脱氢酶的合成,有助于维持厌氧氨氧化活性. 饥饿恢复前后厌氧氨氧化菌属的相对丰度无显著差异,其中Candidatus Kuenenia经30 d恢复后相对丰度提升86%以上,表明其对长期饥饿更具耐受性.     

厌氧氨氧化微生物颗粒化及其脱氮性能的研究

利用厌氧颗粒污泥作为种泥,启动SBR反应器,旨在培养厌氧氨氧化颗粒污泥以及研究其脱氮性能.结果表明,水力停留时间(HRT)是富集厌氧氨氧化微生物的1个重要控制因素,以HRT为30 d,第58 d时,SBR反应器就出现厌氧氨氧化现象,与此同时,颗粒污泥由灰黑色变为棕褐色,粒径减小.到第90 d时,成功培养出厌氧氨氧化颗粒污泥,NH⁺₄-N和NO^-₂-N同时被去除,最大去除速率分别达到14.6 g/(m³·d)和6.67 g/(m³·d).从第110　d开始,逐步降低HRT,以提高基质负荷促进厌氧氨氧化菌生长.到目前t＝156　d,HRT降到5　d,氨氮和亚硝酸氮的去除率分别达到60.6%和62.5%,亚硝酸氮/氨氮的比率为1.12.污泥也由棕褐色变为红棕色,形成红棕色的具有高厌氧氨氧化活性颗粒污泥,总氮负荷达到34.3 g/(m³·d).     

膜曝气生物膜反应器同步硝化反硝化研究

炭膜作为膜曝气生物膜反应器膜组件处理人工合成废水,在单一反应器内实现了同时去碳脱氮.结果表明,当进水COD和NH^＋₄-N浓度分别为338 mg/L和75 mg/L,HRT为14 h,炭膜腔内压力为13.6 kPa时,COD、NH⁺₄-N和TN的去除效率分别为82.5%、 95.1%和84.2%.但是在反应器运行的后期TN去除效率明显下降,主要是因为高有机负荷导致无纺布上的微生物过度繁殖,严重影响了硝化过程的进行.通过荧光原位杂交和扫描电镜技术观察生物膜微生物结构,得出厌氧或兼氧菌主要分布在生物膜外层的缺氧区,而氨氧化菌主要分布在生物膜内层的好氧区.硝化细菌和反硝化细菌在生物膜内的共存实现了炭膜曝气生物膜反应器的同步硝化反硝化.     

厌氧氨氧化菌的培养与推流式反应器氨厌氧工艺

采用推流式固定化絮体生物反应器培养出高活性的厌氧氨氧化(ANAMMOX)红色颗粒污泥.在稳定运行后,反应器的NH₄⁺-N和NO₂^--N去除率皆大于98%,TN平均去除率为86%,NO₃^--N的生成率约为14%,TN去除负荷达2.56kg/(m³·d).同时考察了进水基质比例对反应器性能的影响,并用扫描电镜观察了颗粒结构.     

混合接种PN与PN/A颗粒污泥快速启动连续流自养生物脱氮反应器

在连续流条件下,快速培养亚硝化-厌氧氨氧化（PN/A）颗粒污泥是实现污水高效生物脱氮处理的关键技术. 与PN/A污泥相比,亚硝化（PN）颗粒污泥具有生长周期短、易于批量化培养的优点,并可作为富集厌氧氨氧化菌（AMX）的载体. 在3个完全混合流反应器（R1~R3）中,分别按照质量比3∶1、1∶1和1∶3混合接种PN/A和PN颗粒污泥,并通过设置高氨氮负荷、短水力停留时间和强水力剪切条件,成功启动了连续流自养生物脱氮工艺. 结果表明,尽管R3的启动时长较R1和R2更长,但污泥接种比并未显著影响连续流反应器在稳定状态下的脱氮性能,总氮去除负荷均可达到2.6 kg·（m³·d）^-1以上. 接种的PN颗粒污泥通过提供好氧氨氧化菌种（AOB）,为AMX生长供给了充足的亚硝态氮基质,充分发挥了培养PN/A颗粒污泥的前驱体作用. 由高通量测序结果可知,R1~R3中成熟颗粒的微生物丰度和多样性指数均明显高于接种污泥. AOB（Nitrosomonas属）和AMX（Candidatus Kuenenia和Brocadia属）与Chloroflexi、Bacteroidetes和Chlorobi等异养菌门是驱动自养生物脱氮和维持颗粒结构稳定的关键菌群. 总之,PN与PN/A颗粒污泥的混合接种是快速启动连续流自养脱氮工艺的可行策略,对工程应用具有指导意义.     

常温城市污水同步亚硝化-厌氧氨氧化研究

在常温14.7～24.7℃条件下,以城市生活污水为研究对象,采用SBR反应器,通过调整曝气量控制DO浓度为0.05～0.30 mg/Ｌ,进行了同步亚硝化-厌氧氨氧化试验.结果表明,SBR活性污泥反应器可以在常温条件下实现城市污水氨氮的同步亚硝化-厌氧氨氧化反应;DO可以作为其反应终点的指示参数,本试验确定为1 mg/Ｌ;在SBR探索试验中,NH⁺₄-N消耗速率为0.164～0.218　kg/（m³·d）,NO^-₃-N产生速率为0.026～0.036　kg/（m³·d）,TN脱除速率为0.124～0.194　kg/（m³·d）,去除效率为65%～75％;在SBR改进试验中,分别通过提高温度、增设非曝气运行时段和增加厌氧氨氧化菌生物量3个途径,避免了亚硝酸盐的积累,TN去除效率提高至77%～88%.考虑到脱氮速率和实际的工程应用条件,认为增加厌氧氨氧化菌的生物量是提高SBR反应器脱氮效能的优选途径.     

不同基质条件下厌氧氨氧化SMBBR启动特性研究

通过接种某城市污水处理厂好氧池生物膜,采用NH₄⁺-N+NO₂^--N （SMBBR-1）和NH₄⁺-N+NO₃^--N+HAc （SMBBR-2）两种进水基质启动厌氧氨氧化序批式移动床生物膜反应器（Sequencing Moving Bed Biofilm Reactor,SMBBR）,研究不同基质条件下反应器的启动特性.结果表明,两反应器在运行100 d后均成功启动并稳定运行,在进水负荷分别为0.83和0.32 kg·m^-3·d^-1（以N计）的条件下,氮去除率分别达到81.82%±1.20%和66.35%±4.79%.活性测定结果显示,SMBBR-1和SMBBR-2中Anammox活性分别达到6448.32和1980.32 mg·m^-2·d^-1,表明Anammox菌被成功富集.高通量结果显示,SMBBR-1和SMBBR-2中启动成功后的Anammox菌由Ca.Brocadia和Ca.Jettenia组成,其中,Ca.Brocadia占比分别为11.02%和7.57%,Ca.Jettenia占比分别为2.07%和0.56%.除Anammox菌外,SMBBR-2中还包括Thauera（2.84%）和Flavobacterium菌（0.66%）,其为部分反硝化菌的主导菌属.本研究表明,虽然两种不同基质的启动办法各有利弊,但其均能实现厌氧氨氧化SMBBR的启动,可为主流系统内的Anammox菌快速富集培养提供技术支撑.     

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.     

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.     

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.     

Potential of plant polyphenol oxidases in the decolorization and removal of textile and non-textile dyes

In this study an effort has been made to use plant polyphenol oxidases; potato （Solanum tuberosum） and brinjal （Solanum melongena）, for the treatment of various important dyes used in textile and other industries. The ammonium sulphate fractionated enzyme preparations were used to treat a number of dyes under various experimental conditions. Majority of the treated dyes were maximally decolorized at pH 3.0. Some of the dyes were quickly decolorized whereas others were marginally decolorized. The initial first hour was sufficient for the maximum decolorization of dyes. The rate of decolorization was quite slow on long treatment of dyes. Enhancement in the dye decolorization was noticed on increasing the concentration of enzymes. The complex mixtures of dyes were treated with both preparations of polyphenol oxidases in the buffers of varying pH values. Potato polyphenol oxidase was significantly more effective in decolorizing the dyes to higher extent as compared to the enzyme obtained from brinjal polyphenol oxidase. Decolorization of dyes and their mixtures, followed by the formation of an insoluble precipitate, which could be easily removed simply by centrifugation.     

Removal of heavy metals from sewage sludge by low costing chemical method and recycling in agriculture

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Isolation and preliminary characterization of a 3-chlorobenzoate degrading bacteria

A study was conducted to compare the diversity of 2-, 3-, and 4-chlorobenzoate degraders in two pristine soils and one contaminated sewage sludge. These samples contained strikingly different populations of mono-chlorobenzoate degraders. Although fewer cultures were isolated in the uncontaminated soils than contaminated one, the ability of microbial populations to mineralize chlorobenzoate was widespread. The 3- and 4-chlorobenzoate degraders were more diverse than the 2-chlorobenzoate degraders. One of the strains isolated from the sewage sludge was obtained. Based on its phenotype, chemotaxonomic properties and 16S rRNA gene, the organism S-7 was classified as Rhodococcus erythropolis. The strain can grow at temperature from 4 to 37℃. It can utilize several （halo）aromatic compounds. Moreover, strain S-7 can grow and use 3-chlorobenzoate as sole carbon source in a temperatures range of 10-30℃ with stoichiometric release of chloride ions. The psychrotolerant ability was significant for bioremediation in low temperature regions. Catechol and chlorocatechol 1,2-dioxygenase activities were present in cell free extracts of the strain, but no （chloro）catechol 2,3- dioxygenase activities was detected. Spectral conversion assays with extracts from R. erythropolis S-7 showed accumulation of a compound with a similar UV spectrum as chloro-cis,cis-muconate from 3-chlorobenzoate. On the basis of these results, we proposed that S-7 degraded 3-chlorobenzoate through the modified ortho-cleave pathway.     

Single and joint effects of pesticides and mercury on soil urease

The influence of two pesticides including chlorimuron-ethyl and furadan and mercury （Hg） on urease activity in 4 soils （meadow burozem and phaeozem） was investigated. The soils were exposed to various concentrations of the two pesticides and Hg individually and simultaneously. Results showed that there was a close relationship between urease activity and organic matter content in soil. Chlorimuron-ethyl and furadan could both activate urease in the 4 soils. The maximum increment of urease activity by chlorimuronethyl was up to 14%-18%. There was almost an equal increase （up to 13%-21%） in the urease activity by furadan. On the contrary, Hg markedly inhibited soil urease activity. A logarithmic equation was used to describe the relationship （P〈0.05） between the concentration of Hg and the activity of soil urease in the 4 tested soils. Semi-effect dose （ED50） values by the stress of Hg based on the inhibition of soil urease in the 4 soils were 88, 5.5, 24 and 20 mg/kg, respectively, according to the calculation of the corresponding equations. The interactive effect of chlorimuron-ethyl or furadan with metal Hg on soil urease was mainly synergic at the highest tested concentrations.     

Organochlorine pesticides in soils under different land usage in the Taihu Lake region, China

A field study was conducted in the Taihu Lake region, China in 2004 to reveal the organochlorine pesticide concentrations in soils after the ban of these substances in the year 1983. Thirteen organochlorine pesticides (OCPs) were analyzed in soils from paddy field, tree land and fallow land. Total organochlorine pesticide residues were higher in agricultural soils than in uncultivated fallow land soils. Among all the pesticides, ΣDDX (DDD, DDE and DDT) had the highest concentration for all the soil samples, ranging from 3.10 ng/g to 166.55 ng/g with a mean value of 57.04 ng/g and followed by ΣHCH, ranging from 0.73 ng/g to 60.97 ng/g with a mean value of 24.06 ng/g. Dieldrin, endrin, HCB and α-endosulfan were also found in soils with less than 15 ng/g. Ratios of p,p'-(DDD DDE)/DDT in soils under three land usages were: paddy field ＞ tree land ＞ fallow land, indicating that land usage inlfuenced the degradation of DDT in soils. Ratios of p,p'-(DDD DDE)/DDT ＞1, showing aged residues of DDTs in soils of the Taihu Lake region. The results were discussed with data from a former study that showed very low actual concentrations of HCH and DDT in soils in the Taihu Lake region, but according to the chemical half-lives and their concentrations in soils in 1980s, the concentration of DDT in soils seemed to be underestimated. In any case our data show that the ban on the use of HCH and DDT resulted in a tremendous reduction of these pesticide residues in soils, but there are still high amounts of pesticide residues in soils, which need more remediation processes.     

Alterations of organ histopathology and metallolhionein mRNA expression in silver barb, Puntius gonionotus during subchronic cadmium exposure

Common silver barb,Puntius gonionotus,exposed to the nominal concentration of 0.06 mg/L Cd for 60 d,were assessed for histopathological alterations(gills,liver and kidney),metal accumulation,and metallothionein(MT)mRNA expression.Fish exhibited pathological symptoms such as hypertrophy and hyperplasia of primary and secondary gill lamellae,vacuolization in hepatocytes,and prominent tubular and glomerular damage in the kidney.In addition,kidney accumulated the highest content of cadmium,more than gills and liver.Expression of MT mRNA was increased in both liver and kidney of treated fish.Hepatic MT levels remained high after fish were removed to Cd-free water.In contrast,MT expression in kidney was peaked after 28 d of treatment and drastically dropped when fish were removed to Cd-free water.The high concentrations of Cd in hepatic tissues indicated an accumulation site or permanent damage on this tissue.