Bioremediation of soil contaminated with spent and fresh cutting fluids by Pleurotus pulmonarius (Fries) Quelet

Abstract

Contamination of soil with industrial cutting fluids containing heavy metals and petroleum hydrocarbons has detrimental effects on ecosystems. As such contaminants constitute risk to human health; they can enter the food chain through agricultural products or contaminated drinking water. This growing concern about contamination with cutting fluids makes remediation process imperative. White rot fungus, Pleurotus pulmonarius was investigated in this pilot study for its potential to bioremediate contaminants such as heavy metals and total petroleum hydrocarbon at 10, 20 and 30% contamination levels. Control experiment (0% contamination level) was also set up. The effects of incubation periods on the contents of cutting fluid contaminated soil inoculated with P. pulmonarius after two months was equally studied. Bioremediation efficiently occurred at 10% contamination level. At this level, soil pH was 6.9 and organic carbon, organic matter and phosphate contents increased by 22.4, 21.4 and 3.5%, respectively for spent cutting fluid and by 30.0, 30.1 and 50.0% for fresh cutting fluid respectively after two months of incubation with the fungus. Copper, manganese and nickel decreased significantly by 35.3, 25.0 and 1.5%, respectively for spent cutting fluid contaminated soil and by 10.5, 54.4 and 55.9% respectively for fresh cutting fluid contaminated soil. High percentage degradation of Total Petroleum Hydrocarbon (TPH) at 10% contamination level was about 90.0% for both fresh and spent contaminated soil samples. The cation exchange capacity increased by 50.8 and 38.4% for spent and fresh cutting fluid contaminated soil samples respectively. These results indicate the efficiency of P. pulmonarius as a bioremediating agent of heavy metals and TPH in contaminated soil.

Keywords: Bioremediation, cutting fluids, total petroleum hydrocarbon, cation-exchange analysis, heavy metals.

African Journal of Biotechnology Vol. 12(42), pp. 6091-6097