Technical and economic analyses in the development of bioremediation processes

The very large extent of subsurface and groundwater contamination with toxic organic compounds has prompted research on a number of bioremedial processes. The justification of this research has been to achieve lower overall remedial costs than are incurred by currently existing technologies. Laboratory studies are often undertaken with the notion that a new set of process conditions can reduce reagent consumption or the time for treatment by a significant factor with an attendant reduction in overall remediation costs. Research programs are initiated on the basis of these simple premises. Our work has shown that many research projects have been undertaken for the wrong reasons and that experimental effort has often not been directed toward large-scale implementation. A preliminary process analysis has been shown to be a very valuable component of any research and development program on bioremedial and other innovative technologies. As described in this article, the analysis (1) identifies the critical engineering and cost parameters and (2) provides guidance to the research program in the design of experiments and the collection of data. The methodology is also useful in the review of proposed new technologies and treatment equipment. The article includes an example of a process analysis for an actual development project directed toward the remediation of solids contaminated with chlorinated hydrocarbons to illustrate the benefits and the power of the technique.     

Biodegradation rates of 2-methylisoborneol (MIB) and geosmin through sand filters and in bioreactors

Taste and odour (T&O) causing compounds, in particular, 2-methylisoborneol (MIB) and geosmin, are a problem for water authorities as they are recalcitrant to conventional water treatment. In this study, biological sand filtration was shown to be an effective process for the complete removal of MIB and geosmin, with removal shown to be predominantly through biodegradation. In addition, MIB and geosmin were also effectively degraded in batch bioreactor experiments using biofilm sourced from one of the sand filters as the microbial inoculum. The biodegradation of MIB and geosmin was determined to be a pseudo-first-order reaction with rate constants ranging between 0.10 and 0.58 d⁻¹ in the bioreactor experiments. Rate constants were shown to be dependent upon the initial concentration of the microbial inoculum but not the initial concentration of MIB and geosmin when target concentrations of 200 and 50 ng l⁻¹ were used. Furthermore, rate constants were shown to increase upon re-exposure of the biofilm to both T&O compounds. Enrichment cultures with subsequent community profile analysis using 16S rRNA-directed PCR-DGGE identified four bacteria most likely involved in the biodegradation of geosmin within the sand filters and bioreactors. These included a Pseudomonas sp., Alphaproteobacterium, Sphingomonas sp. and an Acidobacteriaceae member.     

公共管理与公众参与策略：于桥水库水质改善项目

环境问题是在人类的发展与资源的开发过程中产生的 ,是多种因素综合作用的结果 ,解决任何一个环境问题都将涉及到若干部门和公众 ,决不是一个部门所能完全胜任的。因此 ,采用公共管理与公众参与的模式解决环境问题 ,是改善环境质量的必然途径 ,是一个政府环境管理能力的综合体现。文章阐述了公共管理与公众参与的内涵、目标、目的、基本原则和实施程序等。