ABSTRACT
This chapter discusses the use of in-situ bioremediation processes to treat ground water and aquifer solids contaminated with petroleum hydrocarbons under aerobic conditions using indigenous microorganisms. Bioremediation, whether of excavated soils, aquifer solids or unsaturated subsurface materials, is the use of microorganisms to convert harmful chemical compounds to less harmful chemical compounds in order to effect remediation of a site or a portion of a site. Bioremediation systems supply nitrogen, phosphorus, and/or oxygen to bacteria that are present in the contaminated aquifer solids and ground water. Critical to the design of an in-situ bioremediation system are the ground-water flow rate and flow path. Ground-water flow must be sufficient to deliver the required amounts of nutrients and oxygen in a reasonable time frame. During bioremediation of hydrocarbons in aquifers, the rate of degradation is usually controlled by the rate of supply of nutrient and oxygen. Under ideal conditions, in-situ bioremediation can reduce petroleum hydrocarbon levels to nondetectable levels.
