Removal of As(III) and As(V) from wastewater using Corynebacterium glutamicum MTCC 2745 immobilized on Sawdust/MnFe2O4 composite: kinetic, mechanistic and thermodynamic modelling

Abstract

The present study has dealt with the design of simultaneous biosorption and bioaccumulation (SBB) batch system for As(III) and As(V) ions removal from wastewater. Sawdust/MnFe2O4 composite was used as carrier to immobilize Corynebacterium glutamicum MTCC 2745. This methodology was adopted for SBB of arsenic from wastewater. The biosorption capacity of immobilized bacterial cells was 45.43478 and 47.42308 mg/g for As(III) and As(V), respectively, at optimum contact time of 240 min and temperature 30 °C. The existence of functional groups on the cell wall surface of biomass that may interact with As(III) and As(V) was proved by FTIR and SEM–EDX. The results showed that Brouers–Weron–Sotolongo and fractal-like pseudo-second-order models for both As(III) and As(V) were capable to deliver realistic explanation of biosorption/bioaccumulation kinetic. Applicability of mechanistic models in the present study showed that the rate-controlling step in biosorption/bioaccumulation of both As(III) and As(V) was film diffusion rather than intraparticle diffusion. The suitability of proposed model indicated that biosorption/bioaccumulation of As(III) and As(V) ions on the surface of SBB biomass was chemisorptive and exothermic in nature. The use of 0.1% (v/v) formaldehyde as a disinfecting agent inhibited the growth of bacteria existing in the final wastewater discarded.