Laboratory Scale Bioremediation of Soils from Automobile Mechanic Workshops Using Cow Dung

Abstract

The environment is constantly degraded with contamination from the petroleum industry and their by- products, dealing with this problem in most cases further compounds the problem as environmentally unfriendly technologies such as in situ burning have been adopted previously. The efficiency of cow dung for the remediation of automobile mechanic workshops was studied on a laboratory scale. The purpose of the study was to evaluate the nutrient availability and presence of total petroleum degraders in cow dung and efficiency for use as a 'green' technology in our environment. The study was carried out in perforated buckets to allow for leachate collection. A total of 7 buckets were filled with 2.5 Kg of soil and mixed with cow dung in a ratio of 10%-90%, 20%-80%, 30%- 70% in two replicates while the final bucket was filled with control soil not amended with cow dung. The study period was for 56 days (8 weeks). 'Analytes' were obtained from each of the buckets labelled CD 10%, CD 20%, CD 30% and the control on a weekly basis to check for pH, Total Organic Carbon (TOC), Total Organic Nitrogen (TON), Total Petroleum Hydrocarbon (TPH) and Total Petroleum Hydrocarbon Utilizers (bacterial and fungal) and some organisms capable of petroleum degradation were identified in the samples. The pH ranged between 6.8 and 8.2 for the period of study which was not significantly (<0.05) different from the control soil samples. TOC ranged between 2.0 mg/kg and 2.49 mg/kg throughout the period of study and not significantly different from the control samples. TON increased significantly in the soils amended with cow dung by up to 21% compared to control soils which were significantly lower. TPH Degradation observed was 79.38%, 79.03% and 81.72% respectively. The values were significantly higher than the control which had 35.70% reduction. Total Hydrocarbon Utilizers identified included Bacillus Sp., Staphylococcus Sp,. Pseudomonas Sp., Flaviobacterium Sp., Arthobacter Sp., Enterobacter Sp., Trichoderma Sp., Mucor Sp. and Aspergillus Sp. The use of cow dung showed good prospects in bioremediation of automobile workshop soils contaminated with spent oil. The research can further be implemented in a pilot scale study and subsequently on spent oil contaminated sites.