Evaluation of Composting with ‘Spent’ Mushroom Substrate and Sawdust for Remediation of Petroleum Hydrocarbon-Polluted Soil
E. Albert *
Department of Plant Science and Biotechnology, University of Port Harcourt, P.M.B. 5323, Port Harcourt, Nigeria
D. I. Anyanwu
Department of Plant Science and Biotechnology, University of Port Harcourt, P.M.B. 5323, Port Harcourt, Nigeria
*Author to whom correspondence should be addressed.
Abstract
Aim: To evaluate the capacities of composting ‘spent’ mushroom substrate and sawdust with crude oil polluted soil to enhance degradation of petroleum hydrocarbon.
Study Design: The degradation of petroleum hydrocarbon contents of crude oil polluted treatments composted with ‘spent’ mushroom substrate, sawdust and a mixture of ‘spent’ mushroom substrate and sawdust were compared with that of crude oil polluted-not-composted treatment to determine the influence of the compost amendments.
Place and Duration of Study: The Centre for Ecological Studies, Department of Plant Science and Biotechnology, University of Port Harcourt, Nigeria, from March - July 2015.
Methodology: Five buckets were each filled with 1500 g of top alluvial soil and labelled T1 – T5. T1 (i.e. control) was not polluted while the other buckets were each polluted with Bonny Light crude oil at 6.7% (v/w). T2 was not composted with any material after pollution. T3 was mixed with 200 g of ‘spent’ mushroom substrate and T4 with 200 g of sawdust while T5 was composted with a mixture of 200 g of ‘spent’ mushroom substrate and 200 g of sawdust.
Results: Final pH of 8.4±0.1 and 6.4±0.2 were recorded in T1 and T5 respectively. The pH of T2 decreased from 8.8±0.1 to 7.1±0.1 and from 8.7±0.1 to 7.1±0.4 in T3, but increased from 5.3±0.0 to 8.5±0.0 in T4. Percentage total petroleum hydrocarbon contents decreased by 75.5% in T3 and T5 and 64.9% in T4. Average phosphorus contents increased from 0.33±0.0 to 52.60±0.23 mg/kg in T5, 0.33±0.03 to 1.81±0.35 mg/kg in T4 and from 0.36±0.01 to 1.34±0.62 mg/kg in T3 but decreased from 0.35±0.01 to 0.14±0.60 mg/kg in T2. Total nitrogen contents recorded reduction in T2, T3, T4 and T5 and total organic carbon increased in T2, decreased in T4 and was constant in T5 during the experiment.
Conclusion: ‘Spent’ mushroom substrate, sawdust and a mixture of ‘spent’ mushroom substrate and sawdust composted with crude oil polluted soil significantly enhanced removal of soil hydrocarbon content.
Keywords: Pollution, crude oil, bioremediation, composting, ‘spent’ mushroom substrate, sawdust