降解甲基对硫磷菌株YL8的分离、纯化及降解机理

从农药厂污水处理池的活性污泥中分离到1株能降解甲基对硫磷(MP)和对硝基苯酚(PNP)的菌株YL8,经生理生化试验和16SrRNA同源性分析,初步将YL8归类为节杆菌属(Arthrobactersp.).该菌株能以MP和PNP为唯一碳源生长,在5h内将起始浓度为50mg/L的MP降解近90%;在9h内将50mg/L的PNP完全降解.YL8在降解MP的过程中几乎检测不到PNP的产生.     

Rhodococcus sp. Ns对硝基苯酚的好氧生物降解

通过驯化富集培养,从红树林底泥中分离出6株硝基苯酚降解菌,其中Rhodococcus sp.Ns为对硝基苯酚(PNP)与邻硝基苯酚(ONP)的高效降解菌.在好氧条件下该菌可以耐受小于1.8 mmol/L的PNP,能够利用PNP和ONP为唯一碳源、能源和氮源生长并将其完全矿化.研究了Rhodococcus sp. Ns在不同pH、盐度与浓度范围下,PNP的降解特性并探讨了该菌降解PNP的途径.实验得出该菌在盐度＜5‰、pH＞5的条件下能较快生长,1.5 mmol/L的PNP在96h内被完全降解,并检测到至少2种中间产物4-硝基儿茶酚(4-nitrocatechol)和1,2,4-苯三酚(1,2,4-benzenetriol).红树林底泥中固有的细菌对PNP和ONP具有高效降解作用.     

Rhodococcus sp. Ns对硝基苯酚的好氧生物降解

通过驯化富集培养,从红树林底泥中分离出6株硝基苯酚降解菌,其中Rhodococcus sp. Ns为对硝基苯酚（PNP）与邻硝基苯酚（ONP）的高效降解菌.在好氧条件下该菌可以耐受小于1.8 mmol/L的PNP,能够利用PNP和ONP为唯一碳源、能源和氮源生长并将其完全矿化.研究了Rhodococcus sp. Ns在不同pH、盐度与浓度范围下,PNP的降解特性并探讨了该菌降解PNP的途径.实验得出该菌在盐度<5‰、 pH>5的条件下能较快生长,1.5 mmol/L的PNP在96h内被完全降解,并检测到至少2种中间产物4-硝基儿茶酚(4-nitrocatechol)和1,2,4-苯三酚 (1,2,4-benzenetriol).红树林底泥中固有的细菌对PNP和ONP具有高效降解作用.     

Achromobacter xylosoxidans NS12的分离和对硝基苯酚的降解

通过富集培养,从红树林底泥中分离出6株硝基苯酚降解菌,其中Achromobacter xylosoxidans NS12在好氧条件下可耐受小于1.8 mmol/L的邻硝基苯酚(ONP)或3.0 mmol/L的对硝基苯酚(PNP),能以PNP和ONP作为唯一碳源、能源和氮源生长并将其完全矿化,但该菌不能利用间硝基苯酚(MNP)作为唯一碳源和氮源生长.研究发现A.xylosoxidans NS12在降解PNP和ONP组成的混合底物时,PNP的存在可抑制ONP的降解,同时ONP的存在也抑制PNP的降解.此外,在利用PNP和ONP的混合底物时,NS12转化PNP的速率显著地高于转化ONP的速率.红树林底泥中固有的细菌对PNP和ONP具有高效降解作用.     

一株甲基对硫磷高效降解菌的鉴定及特性研究

从长期施用甲基对硫磷(MP)的污染土壤中分离到一株能以甲基对硫磷为唯一碳源和氮源生长的新型降解菌HS-D38,并利用该菌既降解MP.结果表明,该菌既在降解MP的同时,可对中间产物对硝基苯酚(PNP)进行降解.该菌既能利用苯胺类物质作为唯一的氮源生长,又能利用对苯二酚作为唯一的碳源生长.经SDS或吖啶橙消除质粒后,HS-D38降解MP和PNP的能力丧失. 表明该菌降解酶可能由质粒DNA编码.对该菌16S rDNA 进行PCR扩增、测序,运用BLAST检索分析并构建了系统进化树.结合生理生化鉴定结果,HS-D38被鉴定为铜绿假单胞菌(Pseudomonas aeruginosa).      

Achromobacter xylosoxidans NS12的分离和对硝基苯酚的降解

通过富集培养,从红树林底泥中分离出6株硝基苯酚降解菌,其中Achromobacter xylosoxidans NS12在好氧条件下可耐受小于1.8 mmol/L的邻硝基苯酚（ONP）或3.0 mmol/L的对硝基苯酚（PNP）,能以PNP和ONP作为唯一碳源、能源和氮源生长并将其完全矿化, 但该菌不能利用间硝基苯酚（MNP）作为唯一碳源和氮源生长.研究发现A. xylosoxidans NS12在降解PNP和ONP组成的混合底物时,PNP的存在可抑制ONP的降解,同时ONP的存在也抑制PNP的降解.此外,在利用PNP和ONP的混合底物时,NS12转化PNP的速率显著地高于转化ONP的速率.红树林底泥中固有的细菌对PNP和ONP具有高效降解作用.     

降解甲基对硫磷的节杆菌(Arthrobacter sp.)L4菌株的分离和降解特性研究

从生产甲基对硫磷的山东华阳农药厂污水曝气池中,分离到一株能以甲基对硫磷及其降解中间产物对硝基苯酚为唯一碳源生长的细菌L4菌株.经16S rRNA基因序列分析,该菌株被鉴定为节杆菌属(Arthrobacter sp.).用气相色谱法和分光光度法分析L4菌株的降解性能,结果表明,L4在5h内对50mg·L-1的甲基对硫磷和对硝基苯酚的降解率分别为85%和98%,对其它有机磷农药也有良好的降解效果.L4的最适培养条件为pH值7、30℃、接种量30%.     

甲基对硫磷高效降解菌的分离鉴定及降解酶基因的克隆表达

从湖北沙隆达农药厂枵水处理池的活性污泥中分离到一株能以甲基对硫磷(MP)和对硝基苯酚(PNP)为唯一碳源生长的细菌HS-D36,经生理生化试验和16S rDNA同源性分析,初步鉴定为施氏假单胞菌(Pseudomonas stuazeri).该菌在3h内对浓度为50mg˙L-1MP的降解率为90%;在12h内能将50mg·L-1PNP完全降解.HS-D36在以MP为唯一碳源的无机盐培养基上可以耐受800mg·L-1的MP,在LB培养基上可耐受浓度为2000mg·L-1的MP.同时,克隆了甲基对硫磷水解酶基因mpd,并在E.coli中获得高效表达.重组甲基对硫磷水解酶粗酶液活性达到52.5 U·mL-1.     

Burkholderia sp.FDS-1降解硝基苯酚类化合物的特性研究

从长期受农药污染的土壤中分离到1株高效杀螟硫磷降解菌株Burkholderia sp.FDS^-1,它能以3-甲基-4-硝基苯酚(MNP)为唯一碳源和氮源进行生长.该菌能在9h内将0.6mmol.L-1MNP完全转化成邻甲基对苯二酚(MHQ),并能继续降解MHQ.该菌降解MNP的最适温度和pH分别为30℃和7.0,菌株降解MNP的速率和起始接种量呈正相关.降解MNP的酶为诱导酶.     

七株有机磷农药降解菌的降解特性比较

对分离自同一有机磷农药污染土壤的7株有机磷农药降解菌的降解特性进行了比较,7株降解菌都能利用甲基对硫磷为唯一碳源生长,并生成中间代谢产物对硝基苯酚.对硝基苯酚的降解经过一段延滞期,不同菌株降解对硝基苯酚的能力和延滞期有很大差异.降解菌株对多种有机磷类农药和芳香族化合物具有降解能力,其降解谱表现了一定的差异.用PCR方法从7株降解菌中克隆了有机磷农药水解酶基因.     

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.     

基于综合水质标识指数和对应分析法的校园河道水质评价

以三峡大学的校园河道求索溪为研究对象,利用综合水质标识指数法确定求索溪水质类别,分析其水质时空变化规律,并利用对应分析法得出求索溪中不同监测点的主要污染因子.研究结果表明:求索溪整体的综合水质标识指数为7.423,整体水质为劣V类(地表水环境质量标准GB 3838-2002)且黑臭.从时间变化来看,求索溪4月份的水质最差,5月份次之,4、5月份所有监测点的水质都劣于V类且黑臭;8月份水质最好,水质为Ⅳ类;从空间分布来看,8个监测点综合水质标识指数均超过6.0,水质为劣V类,其中6号监测点的水质相对最好,监测点3号的水质相对最差;对应分析法得出求索溪的整体水体污染程度受总氮因子的影响最大,其次为总磷.该研究拟为求索溪及类似校园河道的水环境治理研究提供基础依据和参考.     

Effects of chitosan on growth of an aquatic plant (Hydrilla verticillata) in polluted waters with different chemical oxygen demands

Effects of chitosan on a submersed plant, Hydrilla verticillata, were investigated. Results indicated that H. venicillata could prevent ultrastructure phytotoxicities and oxidativereaction from polluted water with high chemical oxygen demand (COD). Superoxide dismutase (SOD) activity and malondialdehyde (MDA) contents in H. verticillata treated with 0.1% chitosan in wastewater increased with high COD (980 mg/L) and decreased with low COD (63 mg/L), respectively. Ultrastructural analysis showed that the stroma and grana of chloroplast basically remained normal. However, plant cells from the control experiment (untreated with chitosan) were vacuolated and the cell interval increased. The relict of protoplast moved to the center, with cells tending to disjoint. Our findings indicate that wastewater with high COD concentration can cause a substantial damage to submersed plant, nevertheless, chitosan probably could alleviate the membrane lipid peroxidization and ultrastructure phytotoxicities, and protect plant cells from stress of high COD concentration polluted water.     

Removal of cadmium using MnO2 loaded D301 resin

MnO2 loaded weak basic anion exchange resin D301 （Anion exchange resin, macroreticular weak basic styrene） as adsorbent has been prepared and applied to the removal of cadmium. The adsorption characteristics have been investigated with respect to effect of pH, equilibrium isotherms, removal kinetic data, and interference of the coexisting ions. The results indicated that the Cd^2＋ could be efficiently removed using MnO2 loaded D301 resin in the pH range of 3-8 from aqueous solutions with the co-existence of high concentration of alkali and alkaline-earth metals ions. The saturate adsorption capacity of the Cd^2＋ was 77.88 mg/g. The adsorption process followed the pseudo first-order kinetics. The equilibrium data obtained in this study accorded excellently with the Langmuir adsorption isotherm.     

Effect of coagulation pretreatment on the fouling of ultrafiltration membrane

The purpose of this study is to understand the effect and mechanism of preventing membrane fouling, by coagulation pretreatment, in terms of fractional component and molecular weight of natural organic matter （NOM）. A relatively higher molecular weight （MW） of hydrophobic compounds was responsible for a rapid decline in the ultrafiltration flux. Coagulation could effectively remove the hydrophobic organics, resulting in the increase of flux. It was found that a lower MW of neutral hydrophilic compounds, which could remove inadequately by coagulation, was responsible for the slow declining flux. The fluxes in the filtration of coagulated water and supernatant water were compared and the results showed that a lower MW of neutral hydrophilic compounds remained in the supernatant water after coagulation could be rejected by a membrane, resulting in fouling. It was also found that the coagulated flocs could absorb neutral hydrophilic compounds effectively. Therefore, with the coagulated flocs formed on the membrane surface, the flux decline could be improved.     

Penetration analysis of elements and bioleaching treatment of spent refractory for recycling

Acidithiobacillus ferrooxidans ATCC23270 and Acidithiobacillus thiooxidans TM-32 were used for bioleaching of spent refractories of aluminium and copper melting furnaces for their recycling.Firstly,penetration of elements into aluminium melting furnace refractory was investigated and it was found that up to 7 cm from surface was contaminated.Comparison on leaching efficiency by the strains ATCC23270 and TM-32 found that the strain ATCC23270 could treat larger amount of the refractories than the strain TM-32 could do.In the experiment of bioleaching of spent refractory aluminium melting furnace by the strain ATCC23270,high leaching efficiency were obtained on Al,Si,and Ca,and extremely low leaching performance was,however,shown on the rest of elements i.e.,Na,Mn,and Zn.Under the strain TM-32 use,relatively high leaching performance was recognized on Al,Si,Ca,Na,Mn,and Zn.In the experiment of bioleaching for spent refractory copper melting furnace,almost the same leaching trends were shown on Cu,Zn,Al,and Si under the strains ACTT23270 and TM-32 uses.     

Simultaneous removal of ammonium and phosphate by zeolite synthesized from coal fly ash as influenced by acid treatment

Zeolite synthesized from fly ash （ZFA） without modification is not efficient for the purification of NH4＋ and phosphate at low concentrations that occur in real effluents, despite the high potential removal capacity. To develop an effective technique to enhance the removal efficiency of ammonium and phosphate at low concentrations, ZFA was modified with acid treatment and the simultaneous removal of ammonium and phosphate in a wide range of concentration was investigated. It was seen that when compared with untreated ZFA, only the treatment by 0.01 mol/L of H2SO4 significantly improved the removal efficiency of ammonium at low initial concentrations. The behavior was well explained by the pH effect. Treatment by more concentrated H2SO4 led to the deterioration of the ZFA structure and a decrease in the cation exchange capacity. Treatment by 0.01 mol/L H2SO4 improved the removal efficiency of phosphate by ZFA at all initial P concentrations, while the treatment by concentrated H2SO4 （≥0.9 mol/L） resulted in a limited maximum phosphate immobilization capacity （PIC）. It was concluded that through a previous mild acid treatment （e.g. 0.01 mol/L of H2SO4）, ZFA can be used in the simultaneous removal of NH4＋ and P at low concentrations simulating real effluent.