Simulated and experimental evaluation of factors affecting the rate and extent of reductive dehalogenation of chloroethenes with glucose

Carbohydrates such as molasses are being added to aquifers to serve as electron donors for reductive dehalogenation of chloroethenes. Glucose, as a model carbohydrate, was studied to better understand the processes involved and to evaluate the effectiveness for dehalogenation of different approaches for carbohydrate addition. A simulation model was developed and calibrated with experimental data for the reductive dehalogenation of tetrachloroethene to ethene via cis-1,2-dichloroethene. The model included fermentors that convert the primary donor (glucose) into butyrate, acetate and hydrogen, methanogens, and two separate dehalogenator groups. The dehalogenation groups use the hydrogen intermediate as an electron donor and the different haloethenes as electron acceptors through competitive inhibition. Model simulations suggest first that the initial relative population size of dehalogenators and H(2)-utilizing methanogens greatly affects the degree of dehalogenation achieved. Second, the growth and decay of biomass from soluble carbohydrate plays a significant role in reductive dehalogenation. Finally, the carbohydrate delivery strategies used (periodic versus batch addition and the time interval between periodic addition) greatly affect the degree of dehalogenation that can be obtained with a given amount of added carbohydrate.     

双氧水强化微电解法处理硝基苯废水的试验研究

以某化工厂的硝基苯生产废水为研究对象,在小试确定试验条件的基础上,采用双氧水强化微电解法对废水进行处理,探讨双氧水强化微电解法对废水处理的原理及处理工艺条件.实验结果表明：双氧水强化微电解法处理难降解有机废水,效果好,可以提高废水的生化性,为废水的后续处理提供了有利条件,是难生化有机废水处理的有效方法之一.     

城市污水处理厂SBR工艺设计及脱氮效能

介绍了市政建设项目宁海县兴海污水处理有限公司主要的设计参数及各单元运行过程，并总结了该系统对有机物及氮磷的处理效果，分析了SBR工艺生物处理氮的主要影响因素。     

附载型复合光催化剂TiO2·SiO2/beads降解有机磷农药

研究以四异丙醇钛 [Ti( iso- O C3 H7) 4]、硅酸乙酯为原料 ,以空心玻璃微球为载体 ,用溶胶—凝胶法制备可漂浮附载型复合光催化剂 Ti O2 · Si O2 / beads的过程 ,利用附载型复合光催化剂降解有机磷农药。结果表明 ,复合型光催化剂 Ti O2 · Si O2 摩尔比存在最佳值 ,n ( Ti O2 ) / m ( Si O2 ) =30 / 70时 ,光催化剂活性最高 ,其活性是同样降解条件下、同样含量 Degussa P- 2 5Ti O2 的 2倍左右。该光催化剂比表面大 ,吸附性强。并用 XRD和 SEM对附载型复合光催化剂进行表征     

流域水资源管理中的出境水水质目标管理的思考

从出境水水质目标出发，提出出境水水质目标管理的两个阶段、实施及其可行性。     

Degradation of toxaphene in water during anaerobic and aerobic conditions

The degradation of technical toxaphene in water with two kinds of bioreactors operating in sequence was studied. One packed bed reactor was filled with Poraver (foam glass particles) running at anaerobic conditions and one suspended carrier biofilm reactor working aerobically. Chemical oxygen demand (COD), chloride, sulphate, pH, dissolved oxygen, total toxaphene and specific toxaphene isomers were measured. After 6 weeks approx. 87% of the total toxaphene was degraded reaching 98% by week 39. The majority of the conversion took place in the anaerobic reactor. The concentrations of toxaphene isomers with more chlorine substituents decreased more rapidly than for isomers with less chlorine substituents.     

Equilibrium nonaqueous phase liquid pool geometry in coarse soils with discrete textural interfaces

This paper presents a model for the geometry of nonaqueous phase liquid (NAPL) pools and mounds in homogeneous soils and soils with discrete textural interfaces. It is shown that the concepts of capillary pressure-saturation curve hysteresis and entry pressures are integral to the complete conceptualization of pool and mound geometry. Unless hysteresis is included in the analysis, light NAPL (LNAPL) in homogeneous soils cannot exist in pools at all, and dense NAPL (DNAPL) will not mound on horizontal textural interfaces unless lateral confining boundaries are present. The proposed model also implies that remobilization of DNAPL pools will occur at lower hydraulic gradients than those predicted with previous models. Comparing predicted and experimental DNAPL and LNAPL pool thicknesses and the location of an LNAPL lens with respect to the top of the capillary fringe validate the model.     

水中氰化物突发性污染事故应急监测方法研究

旨在研究现场快速测定水中的氰化物。运用比色分析的朗伯 比尔定律和真空工艺设计 ,将复杂繁琐的实验室测试方法和操作程序有机地融合在测试管中。该测试管具有快速、简便和价格低廉等特点 ,测定范围为 0 0 0 5— 0 2 0mg/L。     

应用GIS分析太湖水质的污染现状

随着空间技术和计算机技术的日益发展，地理信息系统（GIS）作为一门技术，不但在地学方面有了较为广泛的应用，而且在环境部门也越来越显出其优势性。以水质采样监测的大量第一手资料为基础，应用GIS工具，对太湖水质的污染现状进行了分析，并对此进行解释提出了可能的解决办法。     

粤北岩溶区的石漠化及其治理对策探讨

粤北岩溶石山地区分布有面积广泛的碳酸盐岩发育多种岩溶地貌。由于该地区的特殊地质、水文、气候等自然因子的影响，其岩溶生态环境脆弱，环境容量低，敏感度高，抗干扰能力弱。在不合理的人类活动和自然因素作用下，易引发出一系列的生态问题。岩溶生态环境开始恶化，植被走向逆向演替等，最后出现大面积的石山，发生石演化观象。