人工湿地基质渗滤特性及净化污水效果

以细沙、细沙和碎石质量比为1∶1、1∶2、2∶1的三种组合,以及煤渣和壤土质量比为1∶1的混合物共五种基质为供试对象,通过比较测定不同基质渗透性,选择渗透性较好的基质搭配填入人工湿地模型中,测定进出水水质,研究基质对系统净化污水的效果.结果表明,渗透性对人工湿地系统净化污水有一定影响,当基质渗透性较好、孔隙率较高时,污水总磷、氨氮、以及化学需氧量去除率较高;随时间延长,各指标去除率降低,其中总磷去除率与时间有较好的线性相关.     

层状双金属氢氧化物覆膜改性人工湿地无烟煤基质除磷

分别选取MgCl2、ZnCl2、CaCl2、CoCl3、FeCl3、AlCl3等6种金属化合物合成9种不同类型层状双金属氢氧化物(LDHs),利用其对垂直流人工湿地无烟煤基质进行LDHs覆膜改性;构建模拟基质试验柱,对改性前后的无烟煤基质进行模拟垂直流人工湿地净化污水试验.结果表明:相对于原始无烟煤基质,各种LDHs覆膜改性基质对总磷、溶解性总磷、颗粒态磷和磷酸盐的去除率均有不同程度的提高;Zn2+参与合成的改性基质对总磷、溶解性总磷、颗粒态磷和磷酸盐均有很好的去除效果,其中ZnCo-LDHs和ZnAl-LDHs改性基质对总磷和溶解性总磷的平均去除率超过95%,对磷酸盐平均去除率达到98%以上.     

唐山市南湖湿地水体富营养化治理研究

以芦苇作为人工湿地植物,土壤为基质建立人工湿地,采用人工湿地控制试验的方法深入研究了芦苇和湿地基质对唐山人工湿地南湖污水中氮磷的净化能力以及氮、磷在芦苇根、茎、叶的时空分布和动态变化,实验结果表明：芦苇湿地对污水中的氮、磷的净化效果十分明显,在一个月内对污水中TN的平均去除率可达到61.99%,TP平均的去除率可达51.97%,其中基质吸附和植物吸收作用是湿地脱氮除磷的重要形式。     

六价铬对薏米人工湿地净化生活污水的影响

利用湿生植物薏米构建垂直流人工湿地(CAW),各处理均有不种薏米的湿地为对照(NPW),研究不同浓度的Cr6+(0、20、40mg/L)处理对薏米人工湿地及不同水层区域污水中氮磷净化效果的影响。结果表明:处理31 d时,铬质量浓度为10 mg/L时促进薏米人工湿地对氨氮、总磷的去除;处理10 d、59 d时,铬质量浓度为10、40 mg/L时均表现为抑制。CAW、NPW对生活污水中氨氮、总磷的去除率均随铬处理时间延长而降低,且铬质量浓度为0、10 mg/L时NPW的降幅较大。薏米人工湿地对氨氮、总磷的去除效果优于无植物的对照(NPW),2种湿地均表现出湿地下层的去除率高于中层的。     

美人蕉人工湿地对城市生活污水的净化研究

研究了在土壤、黄沙、粉煤灰3种基质不同组合中的美人蕉人工湿地对城市生活污水的净化效率,并探讨了流量对城市生活污水中各污染物去除效率的影响。研究结果表明:流量对美人蕉系统处理污水效果的影响较大,实验中3L/d流量处理效果较好,对污水的综合净化效率较高;基质装填顺序对TP、TN的去除率有一定影响,而对NH3-N的去除影响不大。美人蕉系统对生活污水中COD、NH3-N、TN、TP和浊度去除效果都较好,对NH3-N的去除率高达99%,美人蕉人工湿地对城市生活污水的净化能力强。     

垂直流人工湿地MgFe-LDHs覆膜改性基质净化效果研究

选取生物陶粒、无烟煤、沸石3种垂直流人工湿地常用基质,采用金属摩尔比(M2+ : M3+)为2:1的MgCl2溶液和FeCl3溶液在碱性条件下共沉淀即时生成MgFe-LDHs,并将其覆膜于所选3种垂直流人工湿地基质表面;构建模拟基质试验柱,对改性前后的6种基质进行垂直流人工湿地模拟柱净化受污染湖水的小试试验,并进行对比分析.结果表明:该种针对垂直流人工湿地典型基质的MgFe-LDHs覆膜改性方式可行;改性后的3种基质对CODCr、氨氮、总磷的净化效果均有不同程度的提高;其中,无烟煤基质的覆膜改性性能最优,改性后的无烟煤基质对CODCr、氨氮、总磷的平均去除率分别超过了80%、60%和90%.     

北方地区人工湿地系统去除氨氮、总磷试验研究

减少排向水体的氨氮和总磷是促进水环境质量好转的有效措施之一。本文根据湿地植物的生长期特点,分不同时段进行了氨氮和总磷净化效果对比。试验表明,人工湿地系统对氨氮的去除率可达到87.1%,对总磷的去除率可达到91.8%,说明了在北方地区利用人工湿地系统去除市政污水中的氨氮和总磷等污染物的可行性,处理方法符合目前水环境生态保护趋势要求。     

人工湿地常用生物陶粒基质LDHs覆膜改性及其除磷效果研究

分别利用3种二价金属化合物和3种三价金属化合物,采用水热共沉淀法在碱性条件下对人工湿地中常用的生物陶粒基质进行层状双金属氢氧化物(LDHs)覆膜改性,并将9种不同类型的LDHs覆膜改性生物陶粒基质和普通生物陶粒基质分别填充于10个垂直流人工湿地模拟实验柱中,进行除磷净化实验.结果表明,9种不同类型的改性生物陶粒基质均能有效提高磷素的净化效果;Zn系LDHs改性生物陶粒对总磷、溶解性总磷、磷酸盐均有很好的处理效果,其中Zn Fe-LDHs、Zn Co-LDHs和Zn Al-LDHs对总磷的平均去除率均在92%以上,对溶解性总磷和磷酸盐的平均去除率均超过95%;其对磷素的净化机理主要集中于物理化学作用,同时还应与其对微生物生长的促进作用有关.     

人工湿地基质微生物状况与净化效果相关分析

了解微生物在湿地基质中的状况对理解人工湿地去除污染物机理具有重要意义。利用混菌法和稀释法，测定了不同植物以及无植物的潜流水平湿地基质中微生物的数量，研究了潜流水平湿地不同空间基质微生物的类群数量以及它们与污水净化效果的关系。结果表明，不同植物的湿地基质微生物数量差异不显著，有植物和无植物湿地的差别不明显；湿地基质中不同空间处微生物数量不相同，一般上层多于下层。在湿地运行条件相对稳定的情况下，湿地基质中会逐渐形成数量和活性比较稳定的生物群落。人工湿地基质中微生物数量与BOD5、TN的去除有显著相关性，说明微生物的作用是去除它们的重要途径；基质中微生物数量与TP的去除率相关性不明显，说明磷的去除尚有其他途径。测定了湿地基质硝化速率，硝化能力与亚硝化细菌的数量呈显著相关。     

湿地植被对污水净化效果分析研究

人工湿地植被种植对污水净化具有显著性的改善作用,分析人工湿地植被种植与污水净化的量化关系,分析人工湿地植被种植对污水改善的原理,建立生态植被污水净化处理模式,采用多元回归分析方法人工湿地植被对水质控制和小型富营养水体生态恢复的效益因素,以营养物的去除率、重金属的去除率以及有机物去除率为指标,分析人工湿地植被种植对污水净化的生态学改善模型。研究表明,人工湿地植被种植能增加水体透明度,降低水体中的富营养物和重金属等物质,对污水具有显著性的改善作用。     

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.     

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.     

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.     

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.     

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.     

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.     

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.