聚砜中空纤维膜生物反应器处理甲苯气体研究

采用疏水性聚砜中空纤维膜生物反应器处理甲苯有机气体,考察了甲苯去除性能的影响因素,结果表明聚砜中空纤维膜生物反应器(MBfR)能高效处理甲苯气体,甲苯去除率可达93%。膜生物反应器启动迅速、抗甲苯负荷能力强。膜生物反应器的适宜运行条件为停留时间为12.3 s,循环液pH=7.2,喷淋密度为5.1 L/(m2·h)。MBfR系统对甲苯气体的最大去除负荷为900 g/(m3·h)。采用聚合酶链式反应-变性梯度凝胶电泳(PCR-DGGE)分子生物学方法技术研究膜生物反应器内微生物群落,结果表明,聚砜中空纤维膜生物反应器内主要有Uncultured bacterium、Rhodanobacter sp、Aeromonas hydrophila strain和Rhodococcus sp.等甲苯的降解优势菌。     

甲硫醇脱臭菌的分离、分子鉴定及应用

以低浓度甲硫醇臭气的生物降解为研究对象, 从不同的菌源中筛选得到一株能高效降解甲硫醇的菌株.运用16S rDNA的分子鉴定技术,确定筛选菌Jll的16S rDNA序列同芸苔根际菌(Rape rhizosphere)的相似性最大(97%),为同属.筛选菌Jll生长迅速,挂膜时间短.将其接种于生物滴滤反应器中,在甲硫醇进气流量为0.3 m3/h,质量浓度为40　mg/m3,运行仅4 d后,其去除率可逐渐升到100%.当进气流量分别为0.3,0.6和1.2 m3/h时,该反应器对甲硫醇的最大去除能力分别为36.2,41.8和16.4 　mg/(m3·h).反应器进气负荷提高到(96±3)　mg/(m3·h),运行一段时间后,恢复适宜的进气负荷,生物滴滤反应器对甲硫醇的去除率很快回升.这表明菌Jll不但降解能力高,而且抗逆性强.      

生物滴滤塔同步降解多组分挥发性有机物的实验研究

采用定向驯化活性污泥接种生物滴滤塔(BTF)同时处理甲苯、甲醇、丙烯酸乙酯挥发性有机化合物(VOCs)混合废气,考察BTF的长期稳定运行性能及微生物平均代谢活性.结果表明,混合气进口浓度低于910mg/m3时,BTF对VOCs混合废气总去除率可维持在80%以上,BTF可高效同步净化中低浓度VOCs混合废气;当进气负荷>120g/(m3·h)时,去除负荷趋于稳定,为100g/(m3·h)左右;CO2的生成量与混合废气的去除负荷的比值为1.731,表明BTF对此3种混合废气有较高程度的矿化;BTF对甲苯、甲醇、丙烯酸乙酯的降解行为符合Michaelis-Menten动力学模型,单位体积最大降解速率rmax分别是为90.9,50.5,58.5 g/(m3·h).平均吸光度(AWCD)值分析结果表明塔内微生物具有较高的代谢活性.     

间歇喷淋营养液对生物滴滤塔净化甲苯的影响

为探索间歇喷淋营养液对生物滴滤塔的影响,以净化甲苯为研究对象,应用FX1N-14MR-001型可编程逻辑控制器(PLC),实现生物滴滤塔的间歇喷淋营养液操作,研究了环境温度、ρ(TN)、营养液喷淋密度和喷/停时间对净化甲苯能力的影响,并对机理进行了分析. 结果表明:当生物滴滤塔系统的气体停留时间为40.70s时,营养液最佳喷淋密度为4.5L/(m2·min),最佳喷/停时间为2min/4min. 当甲苯系统进口负荷小于88.29g/(m3·h)时,甲苯的去除率可达95.0%以上;当进口负荷为186.04g/(m3·h)时,甲苯的去除率为87.6%,系统对甲苯的最大去除能力由连续喷淋时的169.63g/(m3·h)升至248.85g/(m3·h).      

生物滴滤塔净化甲基叔丁基醚废气的研究

应用生物滴滤塔处理甲基叔丁基醚废气,研究其挂膜启动及稳定运行阶段的降解性能,并考察了稳定期该系统的生物群落结构.结果表明,生物滴滤塔在停留时间为60 s,进气质量浓度为100 mg·m~(-3)的条件下,运行23 d后完成挂膜,填料上的生物量明显增加,去除率可维持在70%以上.反应器稳定运行时,去除负荷可达13.47 g·(m3·h)~(-1),矿化率可达68%;用Haldane模型拟合生物滴滤塔中去除负荷的变化趋势,获得理论ECmax为21.03 g·(m3·h)~(-1),KS为0.16 g·m~(-3),KI为0.99g·m~(-3).运用高通量测序技术分析生物膜中的微生物群落结构,发现其中优势菌属为Methylibium sp.和Blastocatella sp.,分别占11.33%和9.95%.     

Fe3O4负载填料强化生物滴滤器净化氯苯性能研究

文章采用共沉淀法制备负载Fe₃O₄的聚氨酯海绵填料,考察生物滴滤器(BTF)不同条件下净化氯苯废气的性能和微生物群落变化。结果表明,负载Fe₃O₄后,BTF系统第18天启动完成,比未负载的缩短7 d;停留时间90、60、30 s时,BTF系统最大去除负荷分别为28.39、38.20和57.87 g/(m³·h),比未负载的相应提高了25.68%、50.63%、73.63%;BTF停运7 d后系统性能在第5天完全恢复。负载Fe₃O₄后填料表面变得粗糙,微生物生长均匀;高通量测序表明,运行80 d后BTF中优势菌种占比上升明显,系统内优势菌门为变形菌门、拟杆菌门、放线菌门,优势菌属为罗河杆菌属、假单胞菌属;负载Fe₃O₄后,微生物群落中菌种组成向具有强降解能力的优势菌种转化,提高BTF净化性能。     

矿化垃圾生物反应器中的细菌多样性分析

为探究准好氧生物矿化垃圾床处理渗滤液过程中的微生物作用机理,研究建立了16S r DNA克隆文库及PCRRFLP技术以研究矿化垃圾反应器的细菌多样性。结果表明:矿化垃圾反应器细菌具有高度多样性,反应器内有36种细菌分别属于13个纲,变形菌纲占绝对优势占70%(其中β-变形占56.5%,γ-变形菌纲占10%),拟杆菌纲、鞘氨醇菌纲,芽孢杆菌纲也具有一定优势;3%的Nitrosomonas属是渗滤液氨氮转化成亚硝酸盐氮的主要功能微生物,由于亚硝酸盐氧化菌不存在或丰度极低,因此造成反应器内亚硝酸盐积累;Thauera属(17%)和Thiobacillus denitrificans属(10%)是反应器内主要优势微生物属,是反应器内反硝化脱氮的功能微生物,由于Thauera属在好氧条件下具有反硝化特性,Thiobacillus denitrificans为严格自养反硝化菌,因此反应器脱氮主要途径为好氧反硝化、自养反硝化。     

生物膜法净化甲苯二甲苯混合废气的研究

在生物滴滤器中对低质量浓度甲苯、二甲苯混合废气的净化性能进行试验研究。结果表明:甲苯、二甲苯的净化率均随入口浓度增加而降低,同样条件下二甲苯净化率明显低于甲苯;单负荷进气且气体流量为200L/h时,甲苯最大生化降解量为79.5g/(m3.h),二甲苯最大生化降解量为47.5g/(m3.h);多负荷进气由于竞争抑制作用导致两者净化程度均有所降低。维持甲苯、二甲苯质量浓度不变,两种废气的净化率η均随气量的增加而减少;在气量为260L/h时,两种化合物生化降解量均达到最大值,适宜停留时间为119s。     

不同pH下生物滴滤塔降解甲苯和硫化氢混气的研究

废气生物处理技术作为一项新型的大气污染控制技术得到广泛应用。实验分别在p H为4.5和7.0条件下,利用生物滴滤塔(BTF)对甲苯和硫化氢混气废气进行降解,为混合废气的高效生物净化提供理论指导。该装置在启动阶段,当空床停留时间(EBRT)为30 s,甲苯浓度为400 mg/m3以上时,p H为4.5和7.0的BTF对甲苯的去除率分别为90%和96%。在稳定阶段,通入2 000~15 000 mg/m3的硫化氢(H2S),发现硫化氢对甲苯的降解无影响.随着实验的进行,p H为7.0比4.5的BTF的生物量高,且压降也略高。p H为4.5和7.0的BTF对甲苯和硫化氢的降解过程符合Michaelis-Menten模型,对甲苯降解的相关系数(R2)分别为0.984 2和0.977 8,单位体积的最大降解速率rmax分别为132.46 g/(m3·h)和93.46 g/(m3·h),相对应的气相饱和常数Ks分别为0.25 g/m3和0.075 g/m3;对硫化氢降解的相关系数(R2)分别为0.969 0和0.971 7,rmax分别为60.24 g/(m3·h)和51.55 g/(m3·h),Ks分别为0.06 g/m3和0.13 g/m3。对CO2生成量分析得:p H为4.5和7.0的BTF矿化率分别为70.7%和74.6%。     

厌氧氨氧化启动过程及微生物群落结构特征

采用UASB反应器以体积比1∶2接种实验室培养的具有厌氧氨氧化(ANAMMOX)功能的厌氧污泥和城市污水厂的好氧污泥,耗时17 d成功启动ANAMMOX反应,启动阶段分为菌体水解期、活性提高期和稳定运行期.稳定运行后,逐步提高反应器容积负荷富集厌氧氨氧化菌,当容积负荷由0.10 kg·(m~3·d)~(-1)增至0.44 kg·(m~3·d)~(-1)时,总氮(TN)去除负荷也随之由0.09 kg·(m~3·d)~(-1)提高到0.42 kg·(m~3·d)~(-1),反应器污泥逐渐由浅红色加深,粒径大于0.2 mm的污泥所占比例由10.90%增至38.37%.采用高通量测序对接种污泥和负荷提高期的污泥进行检测,其中绿曲挠菌门(Chloroflexi)、变形菌门(Proteobacteria)、WWE3门、放线菌门(Actinobacteria)、浮霉菌门(Planctomycetes)等占据主导.随着厌氧氨氧化菌富集程度的增大,脱氮功能菌中的变形菌门所占比例逐渐减少,从21.60%降至14.20%,而浮霉菌门随之增多,相对丰度由0.73%升至15.50%.当反应器的容积负荷增到0.44 kg·(m~3·d)~(-1)时,浮霉菌门中,Candidatus Brocadia属、Candidatus Jettenia属和Candidatus Kuenenia属是主要菌属,Candidatus Brocadia属占13.40%,是主要的厌氧氨氧化菌属.     

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.