PAH Degradation in Artificially Lubricant Contaminated Soil

Abstract

Bioremediation is considered as one of the safer, cleaner, cost effective and environmental friendly technology for the treatment of oil contaminated sites. Various industrial and anthropogenic have activities resulted in contamination of sites due to unawareness regarding production, use and disposal of hazardous substances. Due to the persistence nature of crude oil it remains into soil and effects it’s physical, physiological and biological properties. The spillage of oil leads to the introduction of PAH (polyaromatic hydrocarbons) into the soil. They are ubiquitous in nature and are carcinogenic in nature. Bioremediation of PAH-contaminated soils, sediments, and water can be accomplished in a variety of ways e.g. in situ treatment or ex-situ methods such as bio-piling and composting. In the present study the bacterial isolates were screened for their capability of degrading PAH present in the lubricant contaminated soil. They were characterized through biochemical and physiological testing for their potential of degrading PAH. Two bacterial strains S3 and S4 were isolated on the basis of their growth in enriched as well as minimal media. The degradation of PAH was carried out using the composting method in which organic manure was utilized as well as using bacterial culture. The used lubricant oil was added to sterile soil to form the synthetic sample and compost was added in the different proportions ranging from 0-75% and incubated for a period of 15 days. PAH incubated with different ratio of manure showed 43.74 to 89.56% removal efficiency whereas pure culture S3 and S4 (not identified) showed 79% (S3) and 72 %( S4) degradation on 15th day. Degradation was also observed in samples of soil contaminated with naphthalene and with pure naphthalene 83.8% degradation was observed with S3 culture. Hence manure was considered to be an effective tool in removing contamination of soil with lubricant oil.