水力负荷及固相碳源对BAF+多级土壤渗滤组合工艺处理污水的影响研究

碳源的选择及曝气量的控制是影响多级土壤渗滤系统(multi-soil-laying,即MSL)脱氮效果的重要因素.试验采用BAF+MSL两段式新型组合工艺,避免了传统MSL曝气过量抑制反硝化脱氮的风险.考察了不同水力负荷下,BAF+MSL对生活污水的净化效果,并比较研究了以聚丁二酸丁二醇酯(PBS)为反硝化碳源的MSL-1及木屑为碳源的MSL-2的脱氮除磷效果.结果表明,不同水力负荷下,系统对SS平均去除率为94.08%,对COD的去除率均在80%以上,出水COD在20mg·L-1以下.水力负荷对系统BAF段硝化性能影响较小,对MSL反硝化脱氮影响较大.BAF水力负荷为0.5、1及2m·3m-·2d-1时,BAF对NH4+-N的去除率均在90%以上,对TN的平均去除率依次为26.53%、11.09%、5.71%;对应MSL段水力负荷分别为0.25、0.50及1m·3m-·2d-1时,MSL-1对TN平均去除率分别为87.39%、65.09%、45.56%,MSL-2平均去除率依次为61.51%、42.52%、31.32%.MSL-1脱氮性能明显优于MSL-2,而两者除磷效果区别较小.随着水力负荷增大,MSL对TP去除率依次降低,MSL-1对TP平均去除率最高为91.97%.     

基于BDPs的多级土壤渗滤系统处理受污染河水的试验研究

针对受污染的流入滇池的河流河水,采用具有曝气段和缺氧段的两段式多级土壤渗滤(multi-soil-layering,MSL)系统,开展了在缺氧段添加非水溶性可生物降解多聚物(BDPs)材料PBS颗粒的强化脱氮除磷研究.结果表明,添加PBS碳源可有效解决传统MSL系统因碳源不足而导致的脱氮效果不理想的问题.在河水污染较轻及较重两种情况下,系统对TN的平均去除率分别达到78%、85%,平均单位表面去除负荷分别为9.09g·m-·2d-1、24.55g·m-·2d-1;TP平均去除率分别达到92%、98%,平均单位表面去除负荷分别为0.76g·m-·2d-1、2.02g·m-·2d-1.此外,系统对COD的平均去除率可达到75%以上.     

两段式沸石多级土壤渗滤系统强化脱氮试验

针对两段式沸石多级土壤渗滤系统(MSL)第2段(缺氧段)反硝化不足的问题,采取分段进水的方式,探讨处理生活污水和受污染河流时,MSL系统的强化脱氮效果.结果表明,在分段进水后,MSL系统TN平均去除率提高26%,缺氧段反硝化能力明显提高,但仍存在最终出水NO3--N平均去除率为负值的问题.进一步将进水C/N从0.8增加到2.5后,MSL系统TN去除率从53.7%上升到89.4%,说明适宜的进水C/N是决定MSL系统氮去除能力的因素之一.分段进水对MSL系统有机物和磷的去除效果无明显影响.     

溶解氧和曝气时间对好氧反硝化菌脱氮效果的影响

研究室温条件下SBR反应器中好氧反硝化脱氮过程的实现,并在此基础上研究了溶解氧和曝气时间对好氧反硝化菌脱氮效果的影响。结果表明:升高溶解氧能够明显增加COD去除率;延长曝气时间能够提高COD、NO-3-N、TN去除率;并且在溶解氧浓度为3~4 mg/L、曝气时间为6 h的条件下,好氧反硝化菌对污染物去除率较高并且稳定,对COD、硝态氮和TN的去除率分别达到92.74%、89.41%、71%左右。     

两段式曝气对好氧颗粒污泥脱氮性能的影响

基于4个不同进水条件的小试实验探究,得出所接种好氧颗粒污泥表面异养菌在曝气初期阶段大量消耗碳源,对于NO-2-N和NO_3~--N的反硝化效率较低.为此,实验在常温(20~23℃)条件下,在同一周期内先采用低曝气量曝气之后再用高曝气量曝气的两段式曝气方式运行好氧颗粒污泥SBR反应器,低曝气量时长分别取1、2、3 h这3个阶段分别运行,并运用扫描电镜(SEM)和荧光原位杂交技术(FISH)对颗粒污泥进行分析,结果表明AGS粒径增大,反硝化能力提升,NO-2-N的反硝化速率(以LVSS计)在低曝气时长为2 h时升至最高,达9.66 mg·(g·h)~(-1).亚硝态氮积累率不断升高至77.84%,总氮去除率最高达70%.颗粒污泥内部孔隙增多,且细菌多以球菌、椭球状及杆菌为主,氨氧化菌(AOB)占总菌的比例由13.70%升至15.40%.因此,通过两段式曝气过程实现了短程同步硝化反硝化过程并具有较好的脱氮性能.     

两段式进水两级矿化垃圾反应器处理中晚期垃圾渗滤液

针对矿化垃圾反应器处理中晚期垃圾渗滤液时由于反硝化区缺少碳源而导致总氮去除率不佳的问题,开展以优先利用原水中的有机物充当碳源为目的的两段式进水两级矿化垃圾反应器处理工艺的研究。通过控制反应器的曝气量、好氧区和反硝化区,研究了两段式进水两级矿化垃圾反应器处理垃圾渗滤液的效果。结果表明,当进水渗滤液水力负荷为46.0 L/(m~3·d)时,在第一级反应器底部曝气量为1.86 m~3/(m~3·d),第二级反应器中上部曝气量为0.37 m~3/(m~3·d)的条件下,COD、NH_4~+-N、TP的平均去除率分别为84.1%、92.6%、85.6%,运行稳定后TN平均去除率达76.0%,处理效果较好。     

前置反硝化BAF工艺处理生活污水的脱氮试验研究

应用前置反硝化BAF工艺对生活污水进行试验研究,结果表明水力负荷对该工艺处理效果影响显著.在A段与O段体积比 1∶2、气水比3∶1、回流比200%的条件下,最佳水力负荷为2.80 m3/(m2·h),此时COD去除率在90%左右, NH 4-N去除率大于85%,总脱氮率大于70%;出水COD小于30 mg/L,NH 4-N小于5 mg/L,TN小于15 mg/L;同时发现回流比对系统TN去除效果影响较大.     

强化内源反硝化脱氮及污泥减量化研究

为提高传统污水处理工艺内源反硝化脱氮效率,在系统内部实现污泥减量,设计了水解酸化/缺氧/好氧(H/A/O)生物脱氮及污泥减量化工艺.试验采用连续流处理装置,以实际生活污水为研究对象.结果表明,在进水COD(220～410 mg/L)、NH4 -N(36～58 mg/L)、总水力停留时间为11h、硝化液回流比为300%、无外加碳源和碱度条件下,COD、NH4 -N和TN的平均去除率分别超过90%、95%和75%.在缺氧段碳源充足的条件下,随着硝化液回流比的增加,系统TN平均去除率升高;当碳源不足时,随着硝化液回流比的增加,系统TN平均去除率降低.污水经水解酸化预处理后,反硝化速率大大升高.水解酸化段利用水解酸化作用对回流剩余污泥的减量达到56.2%,污水、污泥经过水解酸化处理,大大提高了系统脱氮效率.以水解酸化作为传统的城市污水及污泥处理工艺,既可有效地改善污水的可生化性,提高系统污染物平均去除率,增强污水处理系统运行的稳定性,又可实现污水、污泥一体化处理.     

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.     

苯酚对厌氧氨氧化污泥脱氮效能长短期影响

通过接种厌氧氨氧化(ANAMMOX)污泥,研究了苯酚浓度对ANAMMOX污泥脱氮效能长短期影响.短期结果表明,随着苯酚浓度的增大,氮去除率快速下降.当苯酚浓度大于600 mg·L-1时,NH+4-N的去除率降低到6%以下,TN的去除率只有10%左右.长期实验结果表明,当苯酚浓度小于100 mg·L-1时,NH+4-N的去除率都能达到99%以上,说明低浓度苯酚对ANAMMOX菌有一个驯化的过程.当苯酚浓度高于400 mg·L-1时,NH+4-N的去除率只有23.59%,TN去除率只有50.3%,ANAMMOX污泥抑制明显,与短期结果相同.此时反硝化菌活性明显高于ANAMMOX菌,说明苯酚可作为有机碳源诱发体系中发生反硝化反应,最终导致反硝化菌在体系中占据主导地位.但高浓度(1 000 mg·L-1)苯酚对反硝化菌也具有抑制作用.通过拟合得到苯酚对ANAMMOX半抑制有效浓度(IC50)为71.57 mg·L-1.经过18 d的恢复后,NH+4-N去除率基本恢复,但氮素之间的转化计量式发生了改变,ρ(NH+4-N)去除/ρ(NO-2-N)去除/ρ(NO-3-N)生成为1∶0.86∶0.2.研究结果表明,将苯酚控制在合理范围内可以使反应器达到同步脱氮除酚的效果.     

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.     

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.