Comparative Analysis And Prediction Of Remediation Rates Of Microbes In Simulated Polluted Soil Samples

ABSTRACT 

The study compared and predicted the remediation rates of microbes using the rate removal of Total Petroleum Hydrocarbon Content (TPHC) of a crude oil polluted land. This  was done using field experimental data generated from the soil of the Federal University of Technology Owerri Research Farm in Imo State, Nigeria. The soil was artificially polluted in the laboratory with crude oil - Bonny light - with specific gravity of 0.8323. Petroleum contaminant present in the soil was 230mg per kilogram of soil. The treatment variables used include: inorganic fertilizer (NPK 20:10:10), poultry manure, cow dung and a mixture of the three in equal proportions. In addition, a natural treatment was allowed to occur as the control experiment. Fungi as well as bacteria were discovered to have played an important role in the degradation of petroleum hydrocarbon. The fungi identified responsible for degrading crude oil are: Penicillium notatum, Mucor spp, Rhizopus stolonifer and Penicillum caseicolum with P.notatum and P.caseicolum (penicillum spp) as the strongest fungi degraders. The identified degrading bacteria are Pseudomonas putida and Bacillus subtilis. These can therefore be isolated and cultured and then employed on remediation sites either as indigenous or foreign degrading microbes in the bioremediation of crude oil polluted soil. The mixture of treatment variables proved to be a better option from the results obtained with the value of the TPHC as 82.38mg/kg after 9weeks of remediation followed by fertilizer with a value of 83.13mg/kg and 86.75mg/kg for poultry manure for the same period. However, the cow dung treatment had a value of 105.5mg/kg and the control experiment had the least with 204.50mg/kg. A comparison was done with results obtained from the study and two other similar works which showed the rates of remediation of the mixture of the treatment variables as 64% reduction in 9weeks for the study compared to 67% reduction in 9weeks for an earlier work. This study therefore recommends the remediation of crude polluted land using the direct application of the microbial cultures of the identified degrading microbes in this study as an alternative method for remediation of crude polluted site.