Mycoremediation of petroleum hydrocarbon polluted soil by Pleurotus pulmonarius

Abstract

Mycoremediation of petroleum hydrocarbon polluted soil was investigated using Pleurotus pulmonarius for a period of 62 days. Hydrocarbon (Petrol + diesel + spent petrol engine oil + spent diesel engine oil in ratio 1:1:1:1) polluted soil in 2.5%, 5%, 10% and 20% concentration were inoculated and incubated with pure culture of P. pulmonarius obtained from commercial mushroom laboratory of Federal Institute of Industrial Research Oshodi (F.I.I.R.O.) Lagos Nigeria. Inoculation was done by adding 20 g of vigorously growing spawn of P. pulmonarius. A set of control treatment was used where different concentrations of the petroleum hydrocarbon were added to all soils but no inoculation with the fungus. The results showed that the initial organic matter content of the soil increased with increase in the concentration of petroleum mixture added to the soil.  The highest impact of P. pulmonarius on the organic matter content of the soil was noticed in soil with 10% concentration treatment (68.34%) and the least was in soil with 2.5% treatment concentration (22.12%). The initial nitrogen, potassium and phosphorus contents of the soils samples decreased with increase in the petroleum concentration. The difference was significant at 2.5%, 5%, 10% and 20% concentration of contamination for organic matter, nitrogen, potassium and phosphorus (p<0.05). A significant (p<0.05) reduction in concentration of the heavy metals (manganese, copper, and zinc) after 62 days of incubation with P. pulmonarius suggested that the mushroom is a good agent for heavy metal remediation. The highest reduction of Mn was at 10% concentration (24.00±0.04 to 1.73±0.10), Cu at 10% concentration (37.24± 0.02 to 0.00), and Zn was at 10% concentration (63.03±0.02 to 5.75±0.14). The percentage loss of the TPH due the growth of P. pulmonarius decreased with increase in the concentration of petroleum added to the soil. The percentage loss for 2.5%, 5%, 10% and 20% concentration are 52.60%, 38.71%, 27.20% and 8.31% respectively. Heptane, toluene, octane, M-p xylene, Alpha xylene, nonane, propylbenzene, decane, tridecane, tetradecane, anthracene and pentadecane had high reduction; however, the reduction is more significant (p<0.05) in soil inoculated with P. pulmonarius. Our results suggest that P. pulmonarius can be used to clean soils polluted with moderate level of petroleum products mixture

Key Word: Mycoremediation, petrol, diesel, spent engine oil, P. Pulmonarius, TPH