Heavy metal pollution due to coal washery effluent and its decontamination using a macrofungus, Pleurotus ostreatus

Release of the effluent generated during washing of coal became a major problem for coal industries due to presence of many toxic metals and other pollutants. These effluents are the main source of pollution in rivers and other water bodies. Therefore in this study, we tried to analyse the toxicity of coal washery effluent (CWE) collected from one of the washery plant situated in Dhanbad, India. CWE was found to be very toxic containing large amount of suspended particles and many heavy metals above than their permissible limits. Mycoremediation of CWE was also performed to decontaminate heavy metals from the CWE using a macrofungi Pleurotus ostreatus. Efficiency of Pleurotus for remediation of heavy metals was found to be highest in the 50% diluted effluent (57.2% Mn, 82.6% Zn, 98.0% Ni, 99.9% Cu, 99.3% Co, 99.1% Cr, 89.2% Fe and 35.6% Pb) followed by 25% diluted effluent (33.0% Mn, 55.1% Zn, 97.8% Ni, 99.7% Cu, 97% Co, 84.4% Cr, 87.1% Fe and 73.4% Pb) and raw effluent (23.3% Mn, 73.1% Zn, 78.7% Ni, 87.5% Cu, 59.3% Co, 64.6% Cr, 34.6% Fe and 11.3% Pb) respectively. Increased activity of antioxidant enzymes, lipid peroxidation, concentration of metallothionein proteins and changes in peaks of FTIR spectra were also observed in fungal mycelia grown on the CWE containing media due to accumulation of different metals. Overall this study suggests that Pleurotus can be used as promising option for removal of heavy metals from the effluent released from washery plants and dilution of effluent could increase the efficiency of remediation.