Onsite Bioremediation Using Bio Gel on Petroleum Hydrocarbons Contaminated Soil in Zimbabwe

Abstract

Oil spillage is one of the environmental problems faced by Zimbabwe in terms of land contamination with hazardous substances. In Zimbabwe the environmental management act calls for the remediation of oil contaminated sites with best remedial techniques which will remove all the contaminants. This research was done to prove the effectiveness of bio gel in Zimbabwe. Contaminated sites which included the old generator area, fuel storage area and basement area had soil samples and their replicates taken at various depths of 0-30cm, 30-60cm and 60-90 cm. These were analyzed for pH and Total Petroleum Hydrocarbons (TPH) at Scientific and Industrial Research and Development Centre (SIRDC) Laboratory. Multivariate analysis was done using General Linear Model in SPSS version 16.0 statistical software to determine the difference in biodegradation of petroleum hydrocarbon concentration across the sites with change in time and depths. From this study it was concluded that bio gel is effective in removing oils on oil contaminated soils. There was generally a marked decrease in the 0-30cm depth than in 30-60cm and 60-90cm. It was observed that the highest degradation occurred between week 6 and week 8 in the 0-30cm depth. There was an average of 63.4% reduction in the 0-30cm depth at the basement areas and 68.2% reduction in the fuel tanks. The Least Significant Difference Post Hoc tests indicated significant difference in TPH (P<0.05) between weeks. The Least Significant Difference (LSD) Post Hoc tests also indicated significant difference (P<0.05) across sites but there was an insignificant difference between basement area 2 (BS2) and old generator (OG) which was the control.