McCarty P L
Department of Civil Engineering, Stanford University, California 94305.
Basic Life Sci. 1988;45:143-62. doi: 10.1007/978-1-4899-0824-7_9.
This chapter presents some of the engineering challenges in biological degradation of organic contaminants in surface soils and the subsurface environment. Extraction of contaminants from the subsurface is generally costly, slow, and difficult. This has led to an interest in using in situ techniques for biodegradation of contaminants. For some contaminants that can be readily used as primary energy sources for bacteria with or without the presence of oxygen, bacterial removal is relatively simple and, in some situations, occurs naturally. In other cases, such as hydrocarbon spills, in situ treatment is still attractive, but has the added cost and difficulty of supplying required oxygen and nutrients for the fairly efficient aerobic oxidation. There are some indications that hydrocarbons may be biodegraded in the absence of oxygen; but, in these cases, the rates of degradation appear to be slow. More research in this area is desirable. The major challenge to both engineers and scientists lies in the decomposition of hazardous chemicals that appear to be transformed by the process of co-metabolism, or else are so low in concentration that they can only serve as secondary substrates. In either case, primary substrates are required to supply the major energy requirements for bacterial growth and/or for activation of enzymes necessary for the transformation. Engineering experience in the utilization of such processes for degradation of contaminants in the environment is very limited. Little is currently known about substrate interactions and how to optimize the bacterial transformations. Chemical requirements for achieving co-metabolism are high. In addition, knowledge is lacking about methods for getting the correct amounts of chemicals to the locations where needed and in the form needed. The solution of these important issues presents a significant challenge to the engineering and science communities, requiring both basic laboratory studies and field demonstrations in well-characterized environments.
本章介绍了表层土壤和地下环境中有机污染物生物降解方面的一些工程挑战。从地下提取污染物通常成本高昂、速度缓慢且难度较大。这引发了人们对使用原位技术进行污染物生物降解的兴趣。对于一些在有氧或无氧情况下都能被细菌轻易用作主要能源的污染物，细菌去除相对简单，在某些情况下还会自然发生。在其他情况下，如碳氢化合物泄漏，原位处理仍然具有吸引力，但为相当高效的好氧氧化提供所需的氧气和养分会增加成本和难度。有迹象表明碳氢化合物在无氧情况下可能会被生物降解；但在这些情况下，降解速度似乎较慢。该领域需要更多的研究。工程师和科学家面临的主要挑战在于分解那些似乎通过共代谢过程转化的有害化学物质，或者那些浓度极低以至于只能作为次要底物的化学物质。在这两种情况下，都需要主要底物来满足细菌生长的主要能量需求和/或激活转化所需的酶。在环境中利用此类过程降解污染物的工程经验非常有限。目前对底物相互作用以及如何优化细菌转化知之甚少。实现共代谢的化学要求很高。此外，对于如何将适量的化学物质以所需的形式输送到需要的地点的方法也缺乏了解。解决这些重要问题对工程和科学界构成了重大挑战，需要在基础实验室研究和特征明确的环境中进行现场示范。
