Impact of dynamic distribution of floc particles on flocculation effect

Polyaluminum chloride (PAC) was used as coagulant and suspended particles in kaolin water. Online instruments including turbidimeter and particle counter were used to monitor the flocculation process. An evaluation model for demonstrating the impact on the flocculation effect was established based on the multiple linear regression analysis method. The parameter of the index weight of channels quantitatively described how the variation of floc particle population in different size ranges cause the decrement of turbidity. The study showed that the floc particles in different size ranges contributed differently to the decrement of turbidity and that the index weight of channel could excellently indicate the impact degree of floc particles dynamic distribution on flocculation effect. Therefore, the parameter may significantly benefit the development of coagulation and sedimentation techniques as well as the optimal coagulant selection.     

Size distribution and di use pollution impacts of PAHs in street dust in urban streams in the Yangtze River Delta

Particles of dust washed o streets by stormwater are an important pathway of polyaromatic hydrocarbons (PAHs) into urban streams. This article presented a comprehensive assessment of the size distribution of PAHs in street dust particles, the potential risks of the particles in urban streams, and the sources and sinks of PAHs in the stream network. This assessment was based on measurements of 16 PAHs from the USEPA priority list in street dust particles and river sediments in Xincheng, China. The content of total PAHs ranged from 1629 to 8986 g/kg in street dust particles, where smaller particles have a higher concentrations. Approximately 55% of the total PAHs were associated with particles less than 250 m which accounted for 40% of the total mass of street dust. The PAH quantities increased from 2.41 to 46.86 g/m2 in the sequence of new residential, rising through main roads, old town residential, commercial and industrial areas. The sediments in stream reaches in town were found to be sinks for street dust particle PAHs. The research findings suggested that particle size, land use and the hydrological conditions in the stream network were the factors which most influenced the total loads of PAH in the receiving water bodies.     

脉动通风在螺旋隧道施工期的应用研究

为提高施工期通风排除污染物效率,将脉动通风方法应用于螺旋隧道中,通过理论分析研究脉动通风在隧道施工期排除污染物的原理,采用FLUENT软件模拟不同脉动幅值、脉动频率下隧道内污染物浓度变化情况。研究结果表明:脉动通风可有效减少螺旋隧道内涡流区面积,优化隧道风流流场;脉动通风方式可使积聚在涡流区内的污染物产生纵向脉动速度,并加强风流横向脉动;脉动通风对爆破后排出CO气体效果不明显,但对降低喷浆过程粉尘浓度效果显著,数值模拟与理论研究结果吻合;排除污染物效果与脉动幅值无明显关系,与频率关系显著,且频率较小时效果更好。     

呼吸型填埋场覆盖层技术研究Ⅰ：热动力自充氧装置构建

填埋场最终覆盖层（以下简称＂覆盖层＂）中的氧气含量是影响甲烷氧化效果的重要因素.本研究基于空气热力学原理提出了一种呼吸型覆盖层技术,构建了利用垃圾堆体与外界环境的温差而实现覆盖层自充氧的热动力自充氧装置,并优化了其空气/氧气充气效率.结果表明,导气管路内空气流速（v）与温差（ΔT）呈线性关系（v=0.0281ΔT-0....     

寡毛类蠕虫污泥减量技术的稳定性研究进展

对近年来国内外寡毛类蠕虫污泥减量技术的稳定性研究进展进行了系统评述。除了选择适合稳定减量的蠕虫种属以外,蠕虫反应器构造和废水处理工艺流程、污泥减量工艺的运行操作参数、以及活性污泥本身,都是影响寡毛类蠕虫在活性污泥系统中稳定存在并直接影响到其对活性污泥的捕食和削减能力的重要因素。通过对现有研究进行分析,指出寡毛类蠕虫污泥减量工艺投入实际工程应用的技术和经济瓶颈。     

Mercury removals by existing pollutants control devices of four coal-fired power plants in China

The mercury removals by existing pollution control devices in four coal-fired power plants of China were carried out based on a measurement method with the aluminum matrix sorbent.     

自动增氧人工湿地处理农村生活污水脱氮研究

针对人工湿地中溶解氧浓度不足和脱氮率偏低的问题,设计了自动增氧人工湿地进行农村生活污水处理对比试验研究.结果表明,自动增氧湿地内的DO浓度比普通人工湿地高0.3me期mg/L左右,TN、NH<,4><'+>-N去除率分别达到了67.41%、69.114%,比普通湿地高14.57%、19.79%.同时,自动增氧人工湿地系统中的亚硝化细菌、硝化细菌数量均高于普通人工湿地系统,说明自动增氧措施对于提高人工湿地脱氮效率是有效的.     

双道HG—AFS同时测定鲤鱼肝脏中痕量Hg和As

应用氢化物原子荧光法,测定鲤鱼肝脏中痕量Hg和As,该法具有原子吸收和原子发射光谱两种技术优势,同时它具有分析灵敏度高,干扰少,线性范围宽,可多元素同时测定等优点;在KBH4-酸还原体系中同时测定鱼肝中Hg和As,方法检出限分别为Hg：0．33ng／ml和As0．36ng／ml,线性范围分别为：0.1—2.0ng／ml和1．0—20．0ng／ml。加标回收率分别为Hg：96．0％和As：100．6％。分析结果可靠,方法令人满意,并适合大批量样品的分析.     

铅镉胁迫下接种根际细菌和真菌对圆叶无心菜生长和铅镉累积的影响

铅镉胁迫条件下,采用盆栽试验．研究接种云南会泽铅锌矿区Cd超累积植物-圆叶无心菜的根际细菌和真菌,对圆叶无心菜的生长和铅镉累积的影响,结果表明：2株根际真菌（YQ2F-5和YG2F-6）显著增加盆栽圆叶无心菜地上部分的生长,1株根际真菌（YQ2F-5）显著增加盆栽圆叶无心菜的生物量。根际细菌对盆栽圆叶无心莱的生长和生物量没有影响。接种根际细菌和真菌对盆栽圆叶无心菜Pb和Cd的吸收累积没有影响。     

牡丹江流域农业面源污染特征及防治对策研究

牡丹江流域农业面源污染的贡献值大于点源污染。农业面源污染的主要来源中,农田化肥的污染贡献最大,其次是畜禽粪便、生活污水、生活垃圾。区域污染贡献比例中,COD贡献值按大小顺序依次为宁安市、牡丹江市、林口县、海林市。NH3-N、TN、TP贡献值按大小顺序依次为宁安市、林口县、海林市、牡丹江市。结合牡丹江流域农业面源污染的构成特点和现存问题,提出切实可行的农业面源污染防治对策。