Bioremediation of Soil Contaminated with Spent Engine Oil using Pig Dung

Abstract

Studies were carried out to investigate the bioremediation potential of pig dung in a soil contaminated with spent engine oil. Soil samples were obtained from the Ofrima complex, University of Port Harcourt. The soil samples were contaminated with various concentrations (50 ml and 100 ml) of spent engine oil and allowed for 21 days for proper exposure, mimicking natural spill. This was followed by the addition of the pig dung. The experimental setup was labeled sample A (1 kg soil + 100 g pig dung + 50 ml spent engine oil) and sample B (1 kg soil + 100 g pig dung + 100 ml spent engine oil). The physicochemical parameters and the microbiological analysis were done using standard methods. The total petroleum hydrocarbon was analyzed using gas chromatographic methods. Analyses were carried out at 14 days intervals for 28 days. The physicochemical parameter results showed a reduction in pH values in the contaminated soil samples, ranging from 6.21 - 6.65 in sample A and 6.57 - 6.87 in sample B. Temperature values were constant at 230C from day 1 to day 14 in sample A and increased at day 28 to 24 0C, also for sample B, the temperature was constant at 230C from day 1 to day14 and increased at day 28 to 26 0C. The amount of heavy metal (Lead) content decreased from 4.3645 - 1.93676 (mg/kg) and 6.18361 - 3.89654 (mg/kg) for samples A and B, respectively. There was also a significant reduction in the amount of Total Petroleum Hydrocarbon, from 16631.86 - 3280.83 mg/kg for sample A and 18464.73 - 6784.60 mg/kg for sample B. The THB counts for samples A and B ranged from 7.73 - 7.91 and 7.05-8.20 (Log cfu/g), respectively. The fungal counts ranged from 3.99–4.58 and 5.12 - 7.93 (Log cfu/g) for samples A and B respectively. HUB counts ranged from 4.52–5.09 and 4.93- 5.55 (Log cfu/g) for samples A and B, respectively. The HUF counts ranged from 4.12 - 5.49 and 4.13 - 4.70 (Log cfu/g) for samples A and B, respectively. The results clearly showed that microorganisms capable of utilizing total petroleum hydrocarbon were present, also the pig dung showed both bio-stimulation and bio-augmentation tendency to attract high microbial load which supported the bioremediation of the spent engine oil contaminated soil.