Clementina O. Adenipekun

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

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

Biodegradation of polycyclic aromatic hydrocarbons (PAHs) in spent and fresh cutting fluids contaminated soils by Pleurotus pulmonarius (Fries). Quelet and Pleurotus ostreatus (Jacq.) Fr. P. Kumm

The potential of Pleurotus pulmonarius and Pleurotus ostreatus on the degradation of PAHs in spent and fresh cutting fluids (SCF and FCF) contaminated soils was investigated. Different weights of soil samples were contaminated with varying composition (10, 20 or 30%) of spent and fresh cutting fluids separately then inoculated each sample with P . pulmonarius and P. ostreatus separately and incubated at 28 ± 2°C for two months. The samples were analyzed in triplicates for 16 priority polycyclic aromatic hydrocarbons (PAHs) by gas chromatography after extracting with hexane and dichloromethane (3:1). The initial PAHs in the cutting fluids were mainly composed of 2 to 6 fused benzene rings. Significant reductions in PAHs concentrations for SCF and FCF were observed after two months of incubation. The percentage total PAHs remaining in FCF soil ranged from 71.7 to 73.6% when inoculated with P. pulmonarius and 0.93 to 31.0% when inoculated with P. ostreatus. Similarly, the percentage total PAHs remaining in SCF soil ranged from 42.6 to 72.6% when inoculated with P. pulmonarius and 54.9 to 62.2% when inoculated with P. ostreatus. Overall range of PAHs degradation by P. pulmonarius inoculated on FCF contaminated soil was 17.3 to 27.3%, while for P. ostreatus inoculated soil was 69.0 to 99.07% at different contamination levels. In contrast, overall PAHs degradation for P. pulmonarius and P. ostreatus inoculated on SCF ranged from 27.4 to 57.4% and from 37.8 to 45.2%, respectively. Thus, P. ostreatus is found more effective as a biodegradation agent for PAHs in contaminated soils when compared with P . pulmonarius. Key words: Biodegradation, polycyclic aromatic hydrocarbons (PAHs), cutting fluids, Pleurotus ostreatus , Pleurotus pulmonarius.