Bioremediation is any process that uses fungi, green plants, microorganisms, or their waste products to clean up a natural environment that has been contaminated. There are two classifications of bioremediation in-situ, which refers to onsite treatment, and ex-situ, or offsite treatment.
Land farming is a bioremediation method that that treats the upper soil, or it can be used in biotreatment cells. Basically, this method takes contaminated soil which is combined with topsoil and the mixture is aerated regularly. This enhances microbial degradation and is usually done using basic agricultural equipment- which makes it practical and cost effective. It is an older method and has been very successful in removing oily sludge and refinery waste; another use has been to remove hydrocarbons and pesticides from areas of top surface contamination.
There are several factors that limit the effectiveness of the land farming method, the first of which is the requirement for a large amount of space in order to achieve full aeration of the soil. While land farming has been successful, the conditions for it are largely uncontrollable, which can make the amount of time needed for full cleaning widely variable- particularly when dealing with recalcitrant compounds.
Other problems include the fact that inorganic contaminants are usually not degraded; there is a potential release of a large amount of particulate matter during the operation and the more chlorine or nitrates in the compound- the harder it is for this method to degrade. Land farming is most successful with petroleum hydrocarbons, but other successfully removed contaminants include diesel fuel, No. 2 and No. 6 fuel oils, JP-5 jet fuel, and wood-preserving wastes such as pentachlorophenol (PCP) and certain pesticides. Many full scale operations are employed today and land farming is considered a commercial technology References Hersch, Bob “Land Farming” published 2006 retrieved on June 18, 2009 from http://www.cpeo.org/techtree/ttdescript/lanfarm.htm
Singh, Ajay, Ward, Owen “Applied Bioremediation and Phytoremidiation” published 2004 retrieved on June 18, 2009 from http://books.google.com/books?id=ECLOuHW- d2UC&dq=land+farming+bioremediation&source=gbs_navlinks_s