MICROBIAL SYSTEMS FOR IN-SITU SOIL AND GROUNDWATER REMEDIATION

Abstract

The contamination of groundwater by leakage of hydrocarbons or other pollutants from underground storage tanks, distribution systems and various industrial operations is a major environmental problem. Conventional treatment techniques suffer from serious shortcomings which limit their applicability and efficiency. These include high cost and maintenance requirements, the need to transfer the contamination from one medium to another, and the extended duration of the operation. An alternative to these treatments lies in in situ remediation. Biochemical reactions play an important role in many of these in situ remediation technologies. Commonly, micro-organisms degrade organic compounds to recover the chemical energy conserved in the C-C bonds. Complex organic molecules are thereby converted to simpler compounds and, ultimately, to carbon dioxide or methane and water. Parts of some compounds are scavenged to provide the building blocks for new bacterial cells. in situ bioremediation relies on the ability of micro-organisms (bacteria, fungi, algae, protozoa and metazoa), either attached to soil particles or suspended in the pore water, to either convert contaminants into harmless molecules such as carbon dioxide and water, or to immobilize them into non-soluble and stable forms. In natural attenuation micro-organisms just present in the contaminated aquifer degrade o precipitate the present contaminants by consuming naturally present electron donors or acceptors.