Influence of Bacterization of Biostimulant (Maize Chaff) on Hydrocarbon Degradation of Crude Oil Impacted Soil

Abstract

The influence of bacterization of biostimulant (maize chaff) on hydrocarbon degradation of crude oil impacted soil was studied. The study revealed the presence of bacterial isolates with strong crude oil utilization potentials. Pseudomonas aeruginosa, and Bacillus subtilis were the strongest degraders, Micrococcus and Corynebacterium were moderate degraders, Alcaligenes sp, Enterobacter sp and Klebsiella sp exhibited very weak crude oil utilization while Nitrosomonas sp, Nitrobacter sp, Enterococcus sp and Staphylococcus aureus were unable to degrade hydrocarbons. However, results obtained when microbially (B. subtilis) augmented bio-stimulants was used in a Bacterization-Biostimulation (BB) remediation protocol revealed enhanced degradation of crude oil and it components. Viable cell measurement showed that the higher the biostimulants/contaminant (BC) - ratio employed the more the heterotrophic activity but less hydrocarbonoclastic activity. For soils remedied for 8 weeks with bacterized – maize chaff, the degradation rates were remarkably high, 98.25% as against 28.95 % recorded for the control (treatment with maize chaff alone). The best degradation rate (98.28 %) was attained when 10 % was applied at a BC ratio of 3.34: 1. Beyond these ratios the treatments created "diauxic influence”, retarding the growth and activities of hydrocarbonoclastic bacteria while heterotrophic bacteria proliferate. Longer incubation would certainly have led to complete or higher hydrocarbon degradation when hydrocarbonoclastic degradation enters the second log phase. Enhanced remediation with maize chaff using BB protocol is strongly recommended.