Degradation Kinetics of Microbial Consortium Isolated from Diesel Oil Impacted Soil in Delta Park, University of Port Harcourt, Nigeria

Abstract

Heavy-duty generators constitute a form of hydrocarbon pollution but enrich microorganisms to having degradative ability of hydrocarbons hence can be used for remediation. In this study a laboratory treatability (biodegradation screening) study was employed to investigate the hydrocarbon degradation competence of bacteria and fungi. Culture-dependent microbiological and physicochemical analyses was conducted on the soil samples obtained from the polluted site. The total aerobic heterotrophic bacterial and fungi counts increased from 5.0-7.5 (Log10 cfu/mL) between day 0-14 then reduced to 6.5 Log10 cfu/mL. The hydrocarbon-utilizing bacteria increased from 4.5-5.2 (Log10 cfu/mL). Percentage degradation hydrocarbons, attributed to fungi bacteria and bacteria/fungi consortia, were 42.3%, 54% and 70% respectively while the control had 6.0%. The total petroleum hydrocarbon (TPH) removal rate (K) was modelled using the first order kinetics:  y=-0.0398x+9.79; K=0.0398d-1. These results, correspond to a degradation efficiency of 70% and t1/2 of 17 days for the bacterial/fungal consortium. The K values for the other setups were 0.019 d-1, 0.0261 d-1 and 0.0022 d-1 with the corresponding degradation efficiencies of 42%, 54% and 6.01% and half-life of 37 days, 27 days and 315 days for fungi, bacteria and control respectively. This result indicates that the use of microbial consortia has high potentials in remediation of hydrocarbons and other pollutants of concern.