Arthrobacter sp. mediated chromium remediation and copper accumulation from leached liquor for E-waste management

Abstract

Recently, significant research efforts have been directed towards the eco-friendly and cost-effective management of electronic waste (e-waste) using biohydrometallurgy exploiting microbes in the fulfilment of twin objectives; resource recycling and pollution mitigation. In the present study, a bacterium isolated from metalliferous soil, identified as Arthrobacter sp., EIKU3 having the ability to resist heavy metal toxicity and interact with them was exploited to remove metals from dilute waste obtained from waste printed circuit board (WPCB). This bacterium exhibited multidimensional capabilities in copper (Cu) sequestration and chromium (Cr) reduction. At optimum pH (7.0) the bacterium could reduce Cr significantly (>88 %). This bacterium exhibited monophasic, rapid, concentration- and pH-dependent metal adsorption. Biomass grown in minimal media served as biosorbent to remove Cu from both water (70 % in 1 mM Cu concentration) and waste PCB (82 % from 1.5 mM Cu solution) at pH 7.0. Interestingly, biomass grown in municipal wastewater also removed Cu significantly from both water (49 % from in 1.5 mM Cu solution) and leached WPCB liquor (35 % in 1.5 mM adjusted Cu concentration) at pH 7.0. SEM image showed the change of morphology of this pleomorphic isolate and EDX analysis showed no adsorption of Cu onto the surface. Cell fractionation analysis revealed that the majority (77 %) of the absorbed Cu was localized in the cytoplasm. This was well supported by the moderate reduction of zeta potential of Cu loaded cells. These findings indicated the promising ability of Arthrobacter sp. EIKU3 in mitigating Cu and Cr pollution while recovering Cu from WPCB.