C/N比和曝气量影响MBR同步硝化反硝化的研究

通过连续运行MBR研究了C/N比和曝气量对同步硝化反硝化的影响,结果表明,在环境温度13～23℃,MLSS为6.0～6.8 g/L,进水NH⁺₄-N浓度50 mg/L,曝气量0.5 m³/h,HRT为6 h实验条件下,总氮去除率随着进水C/N比的增加而增加,在C/N比为6∶1～8∶1时,TN去除率达到79%～89%,低的C/N比抑制反硝化,过高的C/N比增加了碳源补加的成本。改变反应曝气量,当C/N比为6∶1,曝气量为0.4 m³/h时,TN的去除率达到了最大值85%。曝气量过高或过低,TN去除率均下降。并对在不同曝气量下MBR 内的DO 值分布进行了初步研究。     

我国水源污染事故风险点定量识别方法

水源事故的频发会对城市供水系统产生威胁,有必要针对供水系统风险进行评估和防控。针对水源事故频发及高发因素定量甄别研究,筛选统计了国内近20年来1 900多起水质突发事故案例,梳理了触发水源水质污染的多种因素,通过构建水源水质安全事故树和贝叶斯网络进行了相互验证分析。结果表明：我国水源污染事故主要因素贡献为依次突然排放(0.466)、污染长期累积(0.242)、交通事故(0.109)等;采用贝叶斯网络计算进行验证,其结果与事故树方法一致性较好。该方法有助于水源污染防控工作中风险点甄别和排序,可为我国饮用水安全保障水平的提升提供支撑。     

Enhanced arsenate removal from aqueous solution by Mn-doped MgAl-layered double hydroxides

Environmental Science and Pollution Research - In this study, Mn-doped MgAl-layered double hydroxides (LDHs) were successfully synthesized for efficient removal arsenate from aqueous solution. The...     

Probabilistic health risk assessment of nitrosamines in drinking water of Shaoxing,Zhejiang, China

Environmental Science and Pollution Research - Nitrosamines (NAms) are potent genotoxic and carcinogenic but widely detected in drinking water. This study aimed to investigate the occurrence of...     

Distribution,source, and environmental risk assessment of phthalate esters (PAEs) in water,suspended particulate matter,and sediment of a typical Yangtze River Delta City,China

Phthalates (PAEs) in drinking water sources such as the Yangtze River in developing countries had aroused widespread concern. Here, the water, suspended particulate matter (SPM), and sediment samples were collected from 15 sites in wet and dry seasons in Zhenjiang, for the determination of six PAEs (DMP, DEP, DIBP, DBP, DEHP, and DOP) using the solid-phase extraction (SPE) or ultrasonic extraction coupled with gas chromatography-mass spectrometry (GC-MS). The total concentrations of six PAEs (Σ₆PAEs) spanned a range of 2.65–39.31 μg L^?1 in water, 1.97–34.10 μg g^?1 in SPM, and 0.93–34.70 μg g^?1 in sediment. The partition coefficients (K_d1) of PAEs in water and SPM phase ranged from 0.004 to 3.36 L g^?1 in the wet season and from 0.12 to 2.84 L g^?1 in the dry season. K_d2 of PAEs in water and sediment phase was 0.001–9.75 L g^?1 in the wet season and 0.006–8.05 L g^?1 in the dry season. The dominant PAEs were DIBP, DBP, and DEHP in water and SPM, DIBP, DEHP, and DOP in sediment. The concentration of DBP in water exceeded the China Surface Water Standard. The discharge of domestic sewage and industrial wastewater might be the main potential sources of PAEs. The risk quotient (RQ) method used for the risk assessment revealed that DBP (0.01 < RQ < 1) posed a medium risk, while DIBP and DEHP (RQ > 1) posed a high environmental risk in water, DIBP (RQ > 1) also showed a high risk in sediment.

     

乐山大佛景区景云亭危岩灾害分析及其防治研究

乐山大佛景区离堆山景云亭危岩地处大佛景区乌尤寺附近陡崖地带.危岩严重威胁省级文物保护单位"离堆"、乐山巨型睡佛的"睫毛"-景云亭及"中流砥柱"浮雕等重要景点的安全.通过现场调查、测绘、坑探等手段,结合赤平投影、楔形体稳定性分析,系统地研究了离堆山景云亭危岩体的区域地质环境条件、危岩基本特征及类型、演化发展趋势、影响因素及其稳定性,在此基础上提出了以锚固为主体工程,辅以排水、嵌补工程,对危岩体进行综合工程整治.     

硝酸盐对反硝化除磷过程的影响分析

在厌氧/缺氧间歇反应器内考察了硝酸盐进水浓度及进水方式对反硝化除磷过程的影响。结果表明：在缺氧阶段,反硝化除磷菌(DPBs)可将硝酸盐转化为亚硝酸盐,当硝酸盐浓度较低时,DPBs以亚硝酸盐为电子受体吸磷。进水COD浓度为220 mg/L,正磷浓度为6.8 mg/L,硝酸盐初始浓度为26 mg/L时,系统达到最佳脱氮除磷效果,期间亚硝酸盐浓度积累至10.71 mg/L。采用连续流投加硝酸盐的方式更利于氮磷的高效去除。     

Study on Biodegradable Starch/OMMT Nanocomposites for Packaging Applications

The thermoplastic starch (TPS) and nanocomposite(TPS/OMMT) was prepared with 15% carbamide, 15% ethanolamine and different contents of organic activated montmorillonite (OMMT) by twin-screw extruder with a 130 °C barrel temperature. Fourier transforms infrared spectroscopy and wide angle X-ray diffraction shown that the alkylamine in dodecyl benzyl dimethyl ammonium bromide could react with MMT via cation exchange reaction. After treated, the d(001)space distance of MMT increased from 1.5 to 1.7 nm. Scanning electron microscope revealed that the lower contents of OMMT could disperse well in the matrixes of TPS. The carbamide, ethanolamine and the OMMT could destroy the crystallization behavior of starch, but only the OMMT restrained this behavior for long-term storing. Mechanical properties investigation indicated that the tensile strength and modulus of TPS/OMMT nanocomposites were better than those of TPS, while the elongation at break was descended with the increasing of OMMT contents. When the content of OMMT was 4%, the tensile strength and modulus of TPS was improved from 4.2 and 42 MPa to 6.0 and 76 MPa, respectively.     

苯蒸气在有机膨润土上的吸附动力学

本文研究了苯蒸气在溴化十六烷基三甲基胺（CTMAB）系列单阳离子有机膨润土上的吸附动力学过程。结果表明,苯蒸气在有机膨润土上的吸附符合一级动力学方程,即：r＝KvCo;在12h内,吸附反应均可达到平衡,吸附速率常数（Kv）与温度（T）成正相关,吸附反应的活化能在9．50－17．92kJ.mol^-1之间。