Bioengineering Issues Related to in Situ Remediation of Contaminated Soils and Groundwater

Abstract

Biological processes have been used well over 100 years for the treatment of organic-bearing municipal and industrial wastewaters and municipal landfills. Aerobic biological processes, such as activated sludge and trickling filters, are used in virtually every city in the United States for treating dilute municipal wastewaters. Anaerobic processes are nearly as widely used to convert the concentrated sludges resulting from dilute waste treatment into methane gas, a useful form of fuel. About 30 years ago, it was first realized that by using completely mixed treatment processes, industrial wastewaters can be readily treated even though they contain organic compounds, such as phenol, that are toxic to microorganisms at the concentrations present. This is possible because the degrading microorganisms maintain the concentration of the chemical within the reactor below the toxic threshold. Biological treatment systems for such wastewaters are now common. Thus, a wide variety of biological processes for converting many forms of hazardous chemicals to innocuous end products are well established and extensively used throughout the world.