Bioremediation

Abstract

For several decades now, industrial chemicals have been released into the environment on a massive scale. Many such compounds are readily degraded by soil and aquatic microorganisms but a significant number, bearing structures unrelated to biogenic compounds or those formed by natural processes, degrade slowly or persist and accumulate in the environment where they may present a long-term hazard. Moreover, these so-called xenobiotics often have low aqueous solubility and are adsorbed to paniculate matter, making them less accessible to microbial attack. This improper disposal, misuse and accidental release of toxic organic and inorganic compounds into the environment has resulted in widespread pollution of soils, ground water and the marine environment. As the adverse environmental and health effects of these materials become better associated, increasing attention is being directed towards the development and implementation of innovative technology for cleaning up contamination. A variety of technologies are currently available to treat soils contaminated with hazardous materials, including excavation and burial in a chemically secure landfill, vapor extraction, stabilization and solidification, soil washing, soil flushing, critical fluid extraction, chemical precipitation, thermal desorption and incineration. Many of these physiochemical treatment technologies do not actually destroy the hazardous compounds present; rather, the chemicals may simply be bound in a matrix or transferred from one phase or location to another. Because these methods do not destroy the contamination and because they are often costly, there is a strong incentive to develop and apply innovative aboveground (ex situ) and in place (in situ) remediation methods (Figs. 4, 5, 6).