Bioremediation of Crude Oil-Contaminated Soil using Compost as Bio-Stimulant

Abstract

This study was conducted to investigate the usability of compost as a stimulant for the remediation of crude oil-contaminated soil. 2kg of porous sandy soil was measured into six different equal-sized cells and contaminated with 250 ml of sample crude oil. Masses of solid waste comprising of compost and sawdust were measured in varying amounts of 900g, 750g, 600g, 450g, 300g, and a control sample that had no compost and sawdust. The set-up was left to stand for eight weeks and the residual hydrocarbon content (RHC), pH, and total microbial count (TMC)of these samples were monitored and recorded. The percentage of hydrocarbon degradation that occurred in the treatment cells were; 33.11, 32.2, 31.2, 29.46 and 28.05 respectively, for the individual cells in the order above, while the control had a degradation rate of (0.44%) of the total hydrocarbon content after 8 weeks. pH values varied slightly within the ranges of 6.5-7.5. The TMC average values were 21, 188, 17,125, 15,000, 14,250, 13,125 and 0.1, with the highest count occurring in the sample having 900g of solid waste; followed by the other samples having lesser quantities of solid waste with the least value in the control. The resultant descent in TMC across each of the samples was due to the distribution of waste material in the samples, and the pH of the resulting mixtures remained at optimum, thereby favouring microbial growth across the samples.