Bioremediation potential of Ganoderma lucidum (Curt:Fr) P. Karsten to remove toxic metals from abandoned battery slag dumpsite soil and immobilisation of metal absorbed fungi in bricks

Open disposal of battery slag is a major cause of heavy metals (HMs) pollution in soil. The current decontamination option is soil washing with chemicals whose efficiency is limited owing to high cost of reagents. This prompted the need for an environmentally friendly approach to remediate the contaminated soil. Therefore, the potential of Ganoderma lucidum to remediate heavy metals from an abandoned battery slag was investigated in this study. The heavy metals absorbed fungi were immobilised in bricks. The battery slag contaminated and control soil samples were analysed for HM concentrations before and after incubation with G. lucidium for 1-3 months. The harvested rice straw and mycelia were processed and analysed for HMs concentrations. For immobilizing heavy metals absorbed in mycelia, 5 to 30 g of pulverized mycelia were homogenized with a virgin soil, extruded into moulds and fired in a tunnel kiln for making bricks. The leachability of HMs from the bricks was carried out using TLCP. The concentrations (mg/kg) of Pb(4490 +/- 14), Zn(147 +/- 11), Ni(27.7 +/- 0.2), Cu(19.4 +/- 0.1) and Cd(2.18 +/- 0.06) in dumpsite soil were significantly higher than the corresponding concentrations in the control soil samples. The G. lucidum inoculated on contaminated soil accumulated 138, 29.8, 3.48, 3069 and 1.01 mg/kg of Pb, Zn, Ni, Cu and Cd, respectively. This reveals the strong affinity of G. lucidum for toxic metals. The Pb, Zn, Ni, Cu and Cd immobilised after leaching procedure ranged from 45.3 to 98.10%. Immobilisation of toxic metals hosted by G. lucidum in red bricks can reduce environmental contamination by metals.