DBD协同CuO/MnO2耦合生物滴滤塔降解氯苯的工艺性能分析

以氯苯为目标污染物,选择CuO/MnO_2作为耦合系统中的催化剂,采用介质阻挡放电(Dielectric Barrier Discharge,DBD)技术协同催化作为生物系统的预处理技术,开展废气净化的研究.实验结果发现,耦合生物滴滤塔(Biotrickling Filter,BTF)和单一生物滴滤塔系统分别在13 d和15 d内完成挂膜,氯苯的去除率分别达到100%和97%.稳定运行期,停留时间(EBRT)为90 s时,单一BTF在处理低进气浓度氯苯废气时,去除效果与耦合系统相当;进气浓度较大时,耦合系统的处理效果要明显优于单一BTF.EBRT缩短至45 s时,无论氯苯进气浓度高或低,耦合系统的处理效果均优于单一BTF.单一BTF的最大去除负荷(Eliminatory Capacity,ECmax)为41 g·m~(-3)·h~(-1),在同样实验条件下,耦合系统未达到最大去除负荷,而耦合系统和单一BTF对氯苯的矿化率分别为95%和86%.DBD协同催化能有效改善BTF对于高进气负荷氯苯废气的处理,预处理工艺能强化BTF对氯苯废气的彻底净化.通过对各功能单元对氯苯去除的贡献分析,发现DBD协同CuO/MnO_2工艺主要负责转化氯苯,BTF下段填料主要负责预处理工艺产生的中间产物的矿化,BTF上段填料主要负责剩余氯苯的去除及其矿化.     

利用新型组合填料的生物滴滤塔净化混合废气研究

建立了生物滴滤中试装置,并将前期研发的纹翼多面球和空心多面柱作为组合填料,以甲苯和乙醇混合气为废气,研究了组合填料生物滴滤塔的污染物去除性能.结果表明,装有组合填料的生物滴滤塔能在8 d内完成挂膜,稳定运行时对甲苯和乙醇的去除负荷分别为97.14 g·(m3·h)~(-1)和113.10 g·(m3·h)~(-1).空床停留时间(EBRT)和进气浓度对甲苯去除效果影响明显,当EBRT为21.11 s,甲苯和乙醇最大去除负荷分别为123.34 g·(m3·h)~(-1)和206.36 g·(m3·h)~(-1);受营养液喷淋量影响不明显,本系统最佳液气比为6.82 L·m~(-3).模拟了不稳定工况对系统处理效果的影响,用Na OH溶液减轻填料层堵塞效果明显,并可以3 d内恢复对甲苯和乙醇的去除效果;停运10 d后继续运行,净化性能可迅速恢复.     

生物过滤塔和生物滴滤塔净化α-蒎烯性能比较

分别采用以木屑/泥炭为填料的生物过滤塔(BF)和以聚氨酯小球为填料的生物滴滤塔(BTF)净化α-蒎烯废气,比较两者的挂膜时间及对α-蒎烯的降解性能.结果表明,采用气液相联合方法,过滤塔和滴滤塔分别在21d和27d内完成挂膜;扫描电镜观察表明,填料上生物膜菌群生长良好,优势菌为杆菌和球菌.在α-蒎烯进口浓度80～2200mg.m-3、空床停留时间(EBRT)29～102s条件下,两者对α-蒎烯均有较好的去除效果,过滤塔与滴滤塔的最大去除负荷分别为50g.m-.3h-1和43g.m-.3h-1;滤塔中CO2生成量与α-蒎烯降解量之间呈线性关系,通过线性拟合得出过滤塔与滴滤塔的α-蒎烯矿化率分别为74%与68%,滤塔中减少的α-蒎烯主要被微生物利用而去除.菌落数(CFU)分析表明,在挂膜阶段滤塔微生物数量增长明显,稳定运行阶段菌落数随着EBRT的延长而增加,在EBRT102s条件下单位反应器空间内过滤塔和滴滤塔菌落数分别为5.52×1014cfu.m-3和1.84×1014cfu.m-3.     

聚丙烯环生物滴滤塔去除实际市政污水厂硫化氢性能及微生物群落分析

在非稳态条件下,采用AAO剩余污泥为种泥、聚丙烯环为填料启动生物滴滤塔,处理实际市政污水厂细格栅H2S恶臭气体.研究了生物滴滤塔的启动、稳定阶段的运行模式,在空床停留时间为14 s,进气浓度2. 02～319. 19 mg·m-3,环境温度为7. 8～32. 5℃条件下,平均出气浓度为13. 08 mg·m-3,平均去除率达到91. 8%,最高去除负荷达到78. 37 g·(m3·h)-1.在247d运行中,监测到生物滴滤塔压降在长期运行中维持稳定在96 Pa·m-1.高通量测序表明,生物滴滤塔内的微生物群落发生了改变,Shannon指数由4. 99降低至3. 75,但Pseudomonas和Thiobacillus等功能菌的存在解释了生物滴滤塔较好的去除性能.结果表明,在非稳态条件下,以AAO剩余污泥为种泥的生物滴滤塔可实现H2S的高效去除;聚丙烯环作为填料可以在长期运行中维持稳定的压降;微生物群落在长期高浓度的H2S环境中,多样性降低,但降解性能可以得到提高.     

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%.     

表面活性剂提高滤塔净化氯苯废气性能的研究

通过吐温80(Tween80)、十二烷基磺酸钠(SDS)、十六烷基三甲基溴化铵(CTMAB)3种表面活性剂对恶臭假单胞菌P.putida的微生物静态培养结果表明,CTMAB对P.putida有显著抑制作用,SDS和Tween80在低浓度下对细菌的抑制较小,而当浓度在50 mg/L以上时,对细菌的抑制作用较为明显。在对表面活性剂筛选和确定最优添加浓度后,实验以活性炭纤维(activated carbon on fiber,ACOF)作为生物滴滤塔的填料,将Tween80、SDS加入喷淋液中,研究其对滴滤塔处理氯苯废气效果的影响。结果表明,未添加表面活性剂时滴滤塔需要7 d的启动时间,添加后大约需要4 d就可以看到明显的去除效果;而与SDS相比,添加Tween80能够使滤塔在相同时期内去除效果提高10%。在控制滴滤塔气体停留时间为109 s,氯苯气体入口浓度为3 000~5 000 mg/m3,体积负荷为145 g/(m3·h)时,未加表面活性剂的情况下,滴滤塔去除能力为120 g/(m3·h);添加后,SDS可使滴滤塔的去除能力升高到132 g/(m3·h),Tween80可将其提高到140 g/(m3·h)。     

生物滴滤塔处理苯酚气体研究

采用生物滴滤塔处理苯酚气体,考察了苯酚去除性能的影响因素.结果表明,生物滴滤塔能高效处理苯酚气体,苯酚去除效率可达99.5%,长期运行平均去除效率在98%左右.适宜的运行条件为:停留时间20.6 s,循环液pH值7.0,喷淋密度1.67 m3·(m2·h)-1.采用聚合酶链式反应-变性梯度凝胶电泳(PCR-DGGE)技术研究处理苯酚气体的生物滴滤塔填料表面的微生物,结果表明,生物滴滤塔内有5种降解苯酚的优势菌种:Polaromonas sp.、Acinetobacter sp.、Acidovorax sp.、Veillonella parvula和Corynebacterium sp..采用GC-MS分析出口气样,结果表明丙酮酸(CH3COCOOH)为生物降解苯酚的中间产物,并推测了苯酚生物降解的可能途径.     

基于好氧反硝化的SND生物滴滤塔除氨机制及微生物学分析

采用生物滴滤法除氨时,进气中的氧气会抑制生物反硝化,导致营养液中出现硝酸盐累积,不能真正实现氮素污染物的去除.本研究结合好氧反硝化理论,构建了同步硝化反硝化（SND）生物滴滤塔,探究了SND生物滴滤塔的除氨效率及氮转化规律,并采用16S rRNA技术解析了生物滴滤塔的微生物种群结构.结果表明,与对照生物滴滤塔相比,当停留时间为67 s时,SND生物滴滤塔可快速启动且除氨性能稳定,NH₃去除效率可达95%以上.当停留时间缩短为16 s时,SND生物滴滤塔的NH₃去除效率仍能达到90%,且具有较低的硝酸盐累积特征.高通量测序结果表明,SND生物滴滤塔具有更高的微生物多样性和稀有物种丰富度,其特有的优势菌属主要为黄杆菌属（Flavobacterium）.     

UV-生物过滤联合降解苯乙烯废气的研究

实验采用主波长为185 nm的低压汞灯为紫外光源,泥炭、棕纤维、多孔活性炭为填料的UV-生物过滤塔联合装置净化苯乙烯废气.苯乙烯进气浓度控制在320~583 mg·m-3之间,稳定后去除率能维持在95%以上.UV光解苯乙烯形成醇、醛、羧酸等水溶性较好的可生物降解的物质,能改善生物过滤塔的运行性能.稳定运行阶段,当总停留时间(total residence time,TRT)较长时,进气浓度的变化基本不影响去除率,随着TRT减少,进气浓度对去除率的影响逐渐显现.TRT为102 s时,联合装置的去除负荷随进气负荷的增加而线性增加,去除率达95%以上.TRT为68 s时,进气负荷较低时,去除负荷的变化也遵循上述规律,但当进气负荷大于30 g·(m3·h)-1时,去除负荷逐渐偏离直线并趋于某一定值.若仅考虑苯乙烯浓度的增减,UV光解对苯乙烯的去除贡献率高于生物过滤塔,而系统关停10 d后重启,苯乙烯的去除效果在第4 d就能恢复.     

BF和BTF工艺去除DCM性能比较

分别以营养型缓释填料的生物过滤塔(BF)和聚氨酯小球为填料的生物滴滤塔(BTF)去除二氯甲烷(DCM)模拟废气.结果表明,采用"专属菌+综合菌"挂膜方式,BTF和BF分别在25 d和22 d内完成快速挂膜.扫描电镜结果表明,BF填料表面的菌落结构较为疏松、生物膜较薄,BTF填料表面的菌落结构致密、生物膜较厚.在DCM进口浓度100~1 500 mg·m-3、停留时间25~85 s条件下,BTF和BF对DCM均有较好的去除效果,最大去除负荷分别为22.61 g·(m3·h)-1和29.05g·(m3·h)-1.滤塔中CO2生产量与DCM降解量呈线性关系,经拟合得出BTF和BF的矿化率分别为70.4%和66.8%,且BTF矿化程度好于BF,表明滤塔内减少的DCM主要是被微生物利用降解.滤塔内DCM的降解动力学行为符合Michaelis-Menten模型,BTF和BF单位体积最大降解速率r max分别为22.779 0 g·(m3·h)-1和28.571 4 g·(m3·h)-1,气相饱和常数K s分别为0.141 2 g·m-3和0.148 6 g·m-3.     

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.     

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.     

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.     

Effect of sorbed and desorbed Zn(Ⅱ) on the growth of a green alga (Chlorella pyrenoidosa)

Toxic effect of Zn(Ⅱ) on a green alga (Chlorella pyrenoidasa) in the presence of sepiolite and kaolinite was investigated.The Zn-free clays were found to have a negative impact on the growth of C.pyrenoidosa in comparison with control samples (without adding any clay or Zn(Ⅱ)).When Zn(Ⅱ) was added,the algae in the presence of clays could be better survived than the control samples,which was actually caused by a decrease in Zn(Ⅱ) concentration in the solution owing to the adsorption of Zn(Ⅱ) on the clays.When the solution system was diluted,the growth of algae could be further inhibited as compared to that in a system which had the same initial Zn(Ⅱ) concentration as in the diluted system.This in fact resulted from desorption of Zn(Ⅱ) from the zinc-contaminated clays,although the effect varied according to the different desorption capabilities of sepiolite and kaolinite.Therefore the adsorption and desorption processes of Zn(Ⅱ) played an important part in its toxicity,and adsorption and desorption of pollutants on soils/sediments should be well considered in natural eco-environmental systems before their risk of toxicity to aquatic organisms was assessed objectively.