Cow Dung as a Bioremediation Agent to Petroleum Hydrocarbon Contaminated Agricultural Soils

Petroleum derived products are very important as they are energy source and it is prone to accidental spill regularly during the exploration, production, refining, transport and storage. The characteristics of the hydrocarbon content of the petroleum mixture influence the degradability of individual hydrocarbon components; the simpler the hydrocarbon structure the easier its biodegradability and the complex the hydrocarbon structure the harder its biodegradability. Furthermore, the order of biodegradability of hydrocarbon is alkanes > alkenes > alkynes > aromatics. Bioremediation technologies are effective techniques to mitigate many organic and inorganic contaminants such as hydrocarbons, halogenated organic compounds, halogenated organic solvent, non-chlorinated pesticides and herbicides, nitrogen compounds, radionuclides, heavy metals. Bioremediation is having different strategies like an exploration of indigenous microbial populations, bio-stimulation, temperature, soil pH, bio-augmentation, phytoremediation, photo-degradation, phyto-volatilization and phyto-stabilization. Cow dung, excreta of bovine animal is a cheap and easily available bio-resource on earth. Many traditional uses of cow dung are already known in India. Cow dung harbors a diverse group of microorganisms that may be beneficial to humans due to their ability to produce a range of metabolites. Nowadays, there is an increasing research interest in developing the applications of cow dung microorganisms as a bioremediation agent to hydrocarbon contaminated soils. Microorganisms capable of degrading hydrocarbon pollutants have been identified and isolated from cow dung. These organisms include; Micrococcus sp., Bacillus sp., Pseudomonas sp., Enterobacter sp., Proteus kleibsilla, Aspergillus sp., Rhizopus and Penicillium. Therefore, cow dung is an effective, economical and eco-friendly bioremediation agent which can lead to the complete mineralization of hydrocarbon. The post remediation assessment of residual hydrocarbons in contaminated soil can be done with gas chromatographic fingerprinting technique and phytotoxicity bioassay.