Biostimulation - A Sustainable Remediation of Crude Oil Pollution in the Tropics

Abstract

The autochthonous microorganisms in hydrocarbon polluted soil are aroused for biodegradation by introduction of external nutrient factors. This research aims to show the sustainability of biostimulation in enhancing crude oil degradation in a tropical soil. The contaminated soils (A, B, C, D, E, F, G, H, and I) were treated simultaneously with a combination of NPK fertilizer and saw dust amendment in designed proportions to offer nutrient and a permeable medium suitable for microbial growth and hydrocarbon degradation. The unpolluted soil, control and the treated soil were monitored for total petroleum hydrocarbon (TPH), soil pH, total organic carbon, total nitrogen, total phosphorus, soil texture, hydrocarbon degrading bacteria (HDB) and hydrocarbon degrading fungi (HDF) using standard analytical method and procedures to establish soil restoration efficiency and kinetics of the bioremediation process. The percentage utilization of nitrogen and phosphorus by microorganism were B (85.1%/81.5%), C (82.2%/83.8%), E (88.7%/90.0%), H (92.3%/92.8%) and I (91.5%/92.2%) and culminated in corresponding HDB growth rate of B (0.1840), C (0.1844), E (0.1882), H (0.1921) and I (0.1931). The resultant optimum TPH degradation efficiency of 99% in treatment H at a degradation rate of -0.0479 day-1 in 105 days indicated the effectiveness of the process. The biodegradation process followed first order kinetics with biomass doubling time 3.61 days and a degradation half-life of 14.5 days. Biostimulation is therefore applied to fuel the medium, sustain microbial growth, improve biodegradation rate and ultimately restore the impacted media without any adverse ecological effect.