不同玉米品种对新鲜城市污泥处理效果的初步研究

寻求城市污泥安全农用的方法是当前城市污泥处理处置的重要研究课题之一.采用小区试验,研究了8个玉米品种对新鲜城市污泥处理效果.结果表明:所选择的8个玉米品种均可以在污泥上生长,大丰5品种对锌的累积量最低,04杂1品种对镉累积量最低,会单4品种对铜和铅累积量最低;玉米种植可显著降低城市污泥中的含水率,比不种玉米的对照处理(69.43%)水分去除率提高9.05%~17.50%,有利于城市污泥的干化及后续利用;各玉米品种植株中的总养分(氮+五氧化二磷+氧化钾)均高于有机肥标准(NY525—2012)的总养分要求,而重金属镉和铅的质量浓度除赛田3品种外其他品种均低于农用有机肥标准(NY525—2012)的限量值;玉米种植后城市污泥中的总养分和锌、镉、铜、铅4种重金属质量浓度变化很小.可见,利用玉米处理新鲜的城市污泥既可降低城市污泥中的水分,又可以产生一定量优质的有机肥原料,为城市污泥的资源化利用提供新思路.     

二氧化钛复合型催化剂制备及其微波辅助催化氧化甲苯性能

实验采用溶胶凝胶法和传统浸渍法制备了TiO2-分子筛复合载体及复合载体负载过渡金属与稀土元素催化剂,通过微波辅助催化氧化甲苯的性能实验考察其催化活性.结果表明,复合TiO2明显提高了载体结构的稳定性与耐温性,并使过渡金属铜(Cu)、锰(Mn)和稀土元素铈(Ce)等活性组分在催化剂表面的分散更均匀;在复合载体吸附、吸波性能与多相活性组分催化的共同作用下,Cu-Mn-Ce/TiO2-分子筛催化剂微波辅助催化氧化甲苯的完全燃烧温度仅为175℃,此时甲苯去除率可达99％;15 h的连续性实验表明,TiO2复合型催化剂具有良好的催化活性与稳定性.由催化剂表征分析结果可知,活性组分颗粒的均匀分布与铜、锰氧化物及铜锰尖晶石固溶物等活性相的存在促进了甲苯的催化氧化,锐钛矿型TiO2较高的电子迁移速率与催化剂孔径的增大均有助于甲苯的氧化降解.     

密云水库底泥和库滨区土壤中氨氧化细菌的多样性和丰度

采用分子生物学方法（T-RFLP、定量PCR）研究了密云水库底泥沉积物和库滨带土壤中氨氧化细菌（AOB）的多样性和丰度特征,并使用Canoco for Windows 4.5软件和皮尔森相关系数法,探究了环境因子对AOB群落的影响.结果表明,沉积物和库滨区土壤中AOB的多样性和数量都存在较大的差异.其中,AOB群落被聚成两大类：沉积物与土壤.沉积物样品中AOB群落结构与其它样品差异较大.沉积物中AOB的多样指数最低,而在农田土壤中AOB多样性指数最高.农田土壤中的amoA基因拷贝数最大,是底泥沉积物中的48倍.此外,RDA（Redundancy Analysis）分析表明,在沉积物和水陆交错带土壤中,AOB的优势种与NH₄⁺-N、NO₃^--N、TOC、pH成正相关关系,而在陆相土壤和农田土壤中,AOB的优势种与这些环境因子成负相关关系.其中,TOC是影响AOB的群落结构的关键理化因子.     

三峡库区大宁河枯水期藻细胞的时空分布

本研究旨在为三峡库区大宁河藻华预警提供基础数据,于2011年4～9月期间在大宁河流域选择4个取样点开展藻细胞时空变化研究.藻细胞在时间序列表现为:4～9月,藻种主要以蓝藻、绿藻和硅藻为主,藻密度呈逐步递增趋势;在此期间4个取样点的蓝藻比重均逐步增大,硅藻比重逐步降低,绿藻比重变化不显著.藻细胞在空间分布上表现为:藻密度与水温和叶绿素呈极显著相关,相关系数分别为0.97和0.95,与光照、溶解氧、pH值和可溶性磷盐呈显著相关,相关系数分别为0.87、0.83、0.82、0.82;菜子坝在整个试验期间0 m处藻密度比其他水层的藻密度高,白水河在6月和7月的2.0 m处藻密度最高,双龙在7、8和9月的0 m和2.0 m处藻密度较高,大昌在整个试验期间,藻密度变化不大;不同藻细胞在垂向水层中的比重也随时间的变化而改变,可能是不同藻细胞适合不同生态环境所致.     

pH过程控制对铁炭微电解-Fenton影响中试研究

采用铁炭微电解-Fenton联合工艺处理制药废水生化出水,探讨了初始pH对微电解过程COD降解速率、出水中Fe2+和Fe3+变化规律以及后续Fenton氧化效果的影响,为优化联合工艺提出了微电解反应pH过程控制的理论。采用pH过程控制时,微电解对COD降解速率大大提高,降解过程基本符合零级反应动力学,同时可大大提高Fe2+和Fe3+浓度及总铁析出量。试验结果表明:当初始pH=2.5,以3.0L/h连续性投加稀硫酸100 min,曝气微电解反应2 h,出水再投加1.0mL/L的H2O2进行Fenton氧化2 h,出水COD总去除率可达85.6%;采用pH过程控制可将微电解出水ρ(Fe2+)浓度从48.6 mg/L提高至149 mg/L,COD降解速率从10.9 mg/(L·h)提高至23.8 mg/(L·h)。     

Iron and lead ion adsorption by microbial flocculants in synthetic wastewater and their related carbonate formation

Although microbial treatments of heavy metal ions in wastewater have been studied, the removal of these metals through incorporation into carbonate minerals has rarely been reported. To investigate the removal of Fe^3＋ and Pb^2＋, two representative metals in wastewater, through the precipitation of carbonate minerals by a microbial flocculant （MBF） produced by Bacillus mucilaginosus. MBF was added to synthetic wastewater containing different Fe^3＋ and Pb^2＋ concentrations, and the extent of flocculation was analyzed. CO2 was bubbled into the mixture of MBF and Fe^3＋/Pb^2＋ to initiate the reaction. The solid substrates were analyzed via X-ray diffraction, transmission electron microscopy and energy dispersive spectroscopy. The results showed that the removal efficiency decreased and the MBF adsorption capacity for metals increased with increasing heavy metal concentration. In the system containing MBF, metals （Fe^3＋ and Pb^2＋）, and CO2, the concentrated metals adsorbed onto the MBF combined with the dissolved CO2, resulting in oversaturation of metal carbonate minerals to form iron carbonate and lead carbonates. These results may be used in designing a method in which microbes can be utilized to combine CO2 with wastewater heavy metals to form carbonates, with the aim of mitigating environmental problems.     

Interface-mediated synthesis of monodisperse ZnS nanoparticles with sulfate-reducing bacterium culture

We have created a new method of ZnS nanospheres synthesis. By interface-mediated precipitation method (IMPM), monodisperse ZnS nanoparticles was synthesized on the particle surface of sulfate-reducing bacterium nutritious agar culture. Sulfate-reducing bacterium (SRB) was used as a sulfide producer because of its dissimilatory sulfate reduction capability, meanwhile produced a variety of amino acids acting as templates for nanomaterials synthesis. Then zinc acetate was dispersed into nutritious agar plate. Subsequently agar plate was broken into particles bearing much external surface, which successfully mediated the synthesis of monodisperse ZnS nanoparticles. The morphology of monodisperse ZnS nanospheres and SRB were examined by scanning electron microscopy (SEM), and the microstructure was investigated by X-ray diffraction (XRD). The thermostability of ZnS nanoparticles was determined by thermo gravimetric-differential thermo gravimetric (TG-DTG). The maximum absorption wavelengh was analysed with an ultraviolet-visible spectrophotometer within a range of 199–700 nm. As a result, monodisperse ZnS nanoparticles were successfully synthesized, with an average diameter of 80 nm. Maximum absorption wavelengh was 228 nm, and heat decomposed temperature of monodisperse ZnS nanoparticles was 596°C.     

Interface-mediated synthesis of monodisperse ZnS nanoparticles with sulfate-reducing bacterium culture

We have created a new method of ZnS nanospheres synthesis. By interface-mediated precipitation method (IMPM), monodisperse ZnS nanoparticles was synthesized on the particle surface of sulfate-reducing bacterium nutritious agar culture. Sulfate-reducing bacterium (SRB) was used as a sulfide producer because of its dissimilatory sulfate reduction capability, meanwhile produced a variety of amino acids acting as templates for nanomaterials synthesis. Then zinc acetate was dispersed into nutritious agar plate. Subsequently agar plate was broken into particles bearing much external surface, which successfully mediated the synthesis of monodisperse ZnS nanoparticles. The morphology of monodisperse ZnS nanospheres and SRB were examined by scanning electron microscopy (SEM), and the microstructure was investigated by X-ray diffraction (XRD). The thermostability of ZnS nanoparticles was determined by thermo gravimetric-differential thermo gravimetric (TG-DTG). The maximum absorption wavelengh was analysed with an ultravioletvisible spectrophotometer within a range of 199-700 nm. As a result, monodisperse ZnS nanoparticles were successfully synthesized, with an average diameter of 80 nm. Maximum absorption wavelengh was 228 nm, and heat decomposed temperature of monodisperse ZnS nanoparticles was 596℃.     

潜流人工湿地处理农村生活污水动力学研究

考察潜流人工湿地处理农村生活污水的运行效果,并探寻一级动力学常数的空间变化情况,采用"厌氧调节池+二级串联潜流式人工湿地"工艺处理农村生活污水。结果表明,经过3个月运行后人工湿地对污水中COD、TP、TN和NH3-N的去除率分别达到了79.13%,71.54%,57.26%和60.01%。通过湿地原位检测显示以上各类污染物在生物床内都有较明显的沿程下降趋势,在床体的前半部分污染物的降解较快,后半部分相对缓慢。农村生活污水中污染物去除动力学符合一级动力学模型,一级生物床中COD、TP、TN和NH3-N的去除,Kv均值分别为3.048、2.469、1.625和1.695;二级生物床中Kv均值分别为2.542、1.946、1.383和1.453。生物床Kv呈现出减小的趋势说明生物床前端对各类污染物的降解速率比后端快。生物床间的跌水池的复氧,增加了二级生物床前端的Kv,提高了对污染物的降解速率。     

2种生物反硝化法去除地下水中硝酸盐的研究

采用砂柱装置,在实验室研究了自养微生物和异养微生物2种生物反硝化方法对地下水中硝酸盐的去除效果。自养反硝化反应在以硫作为电子供体的硫/石灰石/细沙反应柱中进行,异养反硝化反应在石灰石/细沙反应柱中进行,进水增加乙醇作为外加碳源。实验结果用以比较2种反硝化方法在硝酸盐去除率、微生物反应动力学和反应产物三者的异同。结果表明,自养反硝化反应中NO3--N去除率达95.4%,异养反硝化反应去除率可达99.3%;分别与Monod微生物0级、1/2级和1级反应动力学方程进行拟合,2种反硝化反应均符合1/2级微生物反应动力学,适合用1/2级微生物反应方程描述;在反应结束阶段,自养反硝化主要反应产物SO42-出水浓度低于250mg/L,异养反硝化副产物CH3OO-易成为二次污染源,异养反硝化的反硝化速率明显高于自养反硝化反应。