Bio-remediation

The term Bio-remediation refers to the use of biological systems for the reduction of pollution from air,aquatic or terrestrial systems. Microorganisms and plants are the biological systems which are generally used. Biodegradation with micro-organisms is the most frequently occurring bioremediation option. Micro-organisms can break down most compounds for their growth and/or energy needs. These biodegradation processes may or may not need air. In some cases, metabolic pathways which organisms normally use for growth and energy supply may also be used to break down pollutant molecules. In these cases, known as co-metabolism, the microorganism does not benefit directly. Researchers have taken advantage of this phenomenon and use it for bioremediation purposes. A complete biodegradation results in detoxification by mineralising pollutants to carbon dioxide, water and harmless inorganic salts. Incomplete biodegradation will yield breakdown products which may or may not be less toxic than the original pollutant. Incomplete biodegradation of tri- or tetrachloroethylene for instance can yield vinylchloride, which is more toxic and

carcinogenic than the original compounds

Biodegradation may occur spontaneously, in which case the expressions “intrinsic bioremediation” or “natural attenuation” are often used. In many cases however the natural circumstances are not favourable enough for

this to happen due to the lack of enough nutrients, oxygen or suitable bacteria. Such situations may be improved by supplementing one or more of these prerequisites. Extra nutrients were for instance disseminated to speed up the breakdown of the oil spilled on 1000 miles of Alaskan shoreline by the super tanker Exxon Valdez in 1989. The future trend in bioremediation increasingly is to look at the speed of unaided biodegradation first and act only if there is insufficient activity to remove the pollutant quickly enough to prevent any expected risks of the pollutant.

1.Waste water and industrial effluents

2.Drinking and Process Water

3.Air and waste gases

4.Soil and land treatment

5.Solid waste