硫自养反硝化去除地下水中硝酸盐氮的研究

研究实际地下水硫自养反硝化动力学过程,考察季节因素(温度)对动力学的影响,实验结果表明,地下水升流式硫自养滤柱反硝化动力学符合1/2级动力学模型,其反应速率常数受温度的影响很大,用阿仑尼乌斯方程计算硫自养反硝化活化能为80.38 kJ/mol。硫自养反硝化产生的硫酸根与反硝化掉的硝酸根离子呈线性相关。在地下水不经任何预处理的条件下,硫自养反硝化仍能有效地脱除地下水中的硝酸盐,反应器出水的pH值仍维持在中性范围。     

建筑物对高架点源大气污染物扩散影响的模拟研究

运用数值方法对城市中高架点源排放大气污染物的扩散规律进行了模拟研究,在计算区域内建立了三维数学模型,并将拉格朗日法描述的颗粒轨道模型耦合到风场。本研究计算了地面风速为3 m/s时的大气流场,并模拟研究了该风场条件下气体污染物的扩散和固体颗粒污染物的运动轨迹。通过分析模拟结果,给出了高架点源中排放的气体污染物的扩散区域和固体颗粒污染物运动轨迹的变化规律。     

剩余污泥发酵产酸特征及基质释放规律研究

剩余污泥发酵既能实现污泥减量,又能获得污水生物脱氮除磷所需的挥发性脂肪酸VFAs等。采用序批式污泥发酵实验,在(30±1)℃的条件下,研究剩余污泥投配比对序批式污泥发酵系统污泥减量、产酸以及基质释放过程的影响,探索VFAs生成最大化的条件。实验结果表明:投加接种污泥不能明显提高序批式污泥发酵系统剩余污泥的减量效果,但可以改善污泥的产酸特性;当污泥投配比大于50%时,发酵过程中将出现2个VFAs浓度峰,且第二次峰浓度更大;较为理想的序批式污泥发酵投配比是60%~80%、发酵时间为5 d或25 d,前者VFAs表观转化率最大(约24%),后者发酵液中VFAs浓度最高(约600 mg/L);发酵过程中,NH4+-N总体呈上升趋势,磷浓度发酵5 d时达到最大值。     

水库型饮用水水源地一级保护区隔离防护工程研究

依托于地理信息系统空间数据管理和空间信息分析的功能,利用高分辨率遥感影像研究隔离方案划定的技术流程。该技术流程主要包括收集水源地基础资料、解译高分辨率遥感影像、提取土地覆盖分类信息、建立空间数据库、划定物理隔离和生物隔离的区段。该种技术流程也适用于地形复杂、一级保护区面积较大的地下型水源地。     

二次纤维稀酸水解糖化的研究

研究了稀酸作用下二次纤维的水解糖化,探讨了水解各因素温度、H2SO4浓度、时间、液固比以及不同酸、催化剂对水解效果的影响。实验结果表明,在H2SO4作用下最佳工艺为:H2SO4质量分数4%,水解温度190℃,水解时间40min,液固比15(mL/g);还原糖得率为33.26%,水解率为56.83%。不同稀酸对OCC的水解,HCl比H2 SO4、H3 PO4、HNO3具有明显的优势;催化剂FeSO4与CuSO4对还原糖得率有显著的促进作用,还原糖得率分别提高了39.66%与22.03%,而Al2(SO4)3对OCC水解没有促进作用。最后,对不同水解时间后的OCC残渣的红外结晶指数以及基团结构变化进行了分析,分析结果与实验结果相一致。     

贝壳粉型煤固硫剂固硫的实验及机理研究

以贝壳粉作为型煤固硫剂,用正交实验的方法研究了影响贝壳粉固硫率的主要影响因素,在高温(1 150℃)时固硫效率达到56.6%,比CaCO3的固硫率提高40%以上,具有较好的高温固硫性。分析得知,贝壳的主要成分为CaCO3,其含钙量在40%左右,贝壳中又含有较高的Na等碱金属元素以及Fe,Al和Si等。用X射线粉末衍射法分析了高温(1 150℃)型煤样生成的灰渣,分析了贝壳粉作为型煤固硫剂在高温下具有较高固硫率的机理。发现CaAlSi2O8为主的复合晶体在高温下包裹在CaSO4的表面,抑制了CaSO4的热分解从而有效地提高了固硫率。     

Functional gene expression of oil-degrading bacteria resistant to hexadecane toxicity

Contamination with oil poses a threat to the environment and to human health worldwide. Biological methodologies have proved to be economical, versatile and efficient for the remediation of pollutants. In this paper, a highly efficient oil-degrading bacterial strain USTB-2 was isolated from an oil production well of Dagang oil field in Tianjin, China. The 16S rRNA sequence of USTB-2 showed 100% similarity with that of Bacillus subtilis BSn5. Hexadecane is one of the most important components in petroleum. The half inhibitory ratio (IC₅₀) of hexadecane inhibited organisms, determined by microcalorimetry, was lower in USTB-2 than in B. BSn5. The results indicate that the strain USTB-2 degrades hexadecane to make it less toxic compared with the normal strain. RT-PCR was used to evaluate the expression of oil-degrading enzymes, specifically 4-hydroxyphenylacetate 3-monooxygenase genes (HPMO). A sharp increase in the expression of HPMO genes was observed for USTB-2, while the expression of HPMO genes in reference strain B. BSn5 remained relatively stable. These methods can be used to study the metabolic potential of microorganisms for in situ oil decontamination.     

Transformation of tetracycline during chloramination: Kinetics,products and pathways

To assess the potential adverse effects stemming from tetracycline (TC) in drinking water or disinfected wastewater, the kinetics of the chloramination of TC was investigated at room temperature, the transformation products and pathways of their generation were elucidated, and their growth inhibiting properties towards sludge bacteria were assessed. The chloramination of TC exhibited pseudo-first-order kinetics with the rate constants (k_obs) ranging from 0.0082 to 0.041 min^?1 at pH of 6–8. Chloramination of TC generated at least 13 discernible products, and the structures of 12 products, including five chlorinated compounds, were identified using LC–ESI–MS. Two main pathways for the generation of these products were proposed: (1) chlorine substitution reactions followed by dehydration; and (2) oxidization by chloramine. The chlorinated products were proposed to be further degraded to small molecules via the scission of benzene rings of TC, and two oxidization products (2,11a-dihydroxy-keto-TC and 6,11-epoxy-2,11a-dihydroxy-TC) were the final products obtained under the experimental conditions. The chlorinated solution, even without detection of TC, exhibited greater than 80% of TC inhibitory effects towards sludge bacteria, suggesting potential effects on microorganisms in aquatic environment.