Global Journal of Earth and Environmental Science

Microbial degradation of Total Petroleum Hydrocarbon (TPH) in crude oil polluted soil ameliorated with agro-wastes was assessed. Six kilogrammes of each composite soil samples collected from three points were weighed into 150 plastic buckets with drainage holes at the base. The soil samples were spiked with 300 ml of crude oil and treated with agricultural wastes (groundnut husk, maize cobs, cassava peels and empty fruit bunch of oil palm husks) in single and combined form. Experimental data for the total petroleum hydrocarbon content of the soils were collected every 30 days for 90 days. Statistical analysis was done using a three-way analysis of variance (3-Way ANOVA) and significant variations were checked using the least significant difference test at 5% probability level. The results showed that there were significant variations in the mean values between the different treatment groups. However, the combined amendments GnH₁₄P + Mac₁₄P, CasP₁₄P + Mac₁₄P and GnH₁₄P + CasP₁₄P at 10% treatment level had the lowest hydrocarbon contents in the soil with mean values of 197.04, 202.89 and 185.34 respectively. While at 90DAST GnH₁₄P + Mac₁₄P and GnH₁₄P + EFBOP₁₄P had reduced TPH in soil with mean values of 82.94 and 84.72 respectively. High percentage degradation rates was observed in soil amended with GnH₁₄P, GnH₁₄P + CasP₁₄P and GnH₁₄P + Mac₁₄P with mean values of 90.85, 89.12 and 88.43% respectively. It was concluded that the combined treatment with groundnut husks enhances microbial proliferation in soil and produces a strong influence in the reduction of total petroleum hydrocarbons in soils.