Bioremediation is a process by which toxic pollutants are degraded to non-toxic forms by utilizing the metabolism of living organisms. Usually micro-organisms are used for bioremediation and those used are called bioremediators. Plants are used in case of phytoremediation and fungi are used in mycoremediation. The process may be done in situ (by treating the pollutants at their site of existence) or ex situ (carrying the waste or pollutants to a new site for treatment).
Basically there are two approaches to bioremediation - Bioaugmentation and Biostimulation. Bioaugmentation involves addition of species or strains of micro-organisms to an area where they are not usually present, inorder to degrade pollutants. Biostimulation differs in that those micro-organisms that are already present in an area and capable of degrading pollutants, are activated and increased by altering the environmental conditions there.
Bioremediation is of increasing importance in the modern world. Waste and pollutants are accumulating worldwide. Treating them with chemicals and other methods are always highly expensive and also produces secondary products that are harmful to the flora and fauna. But treating them using biological methods will produce good results without harmful secondary metabolites. This is a method that is way cheaper too.
Bioremediation has been successfully employed in oil spill treatments, sewage treatments, cleaning of fresh water reservoirs etc. The process is highly advantageous too that its efficiency can be measured by measuring various parameters like redox potential in soil or groundwater, pH, temperature, concentration of breakdown products etc.
The figure shows a microbial cell takes in the pollutant or contaminant as food, along with oxygen and other nutrients, break them down, and release non-toxic final wastes like carbon dioxide and water. Thus a microbial cell is an effective bioremediator.