Removal of arsenic by a Bacillus arsenicus biofilm supported on GAC/MnFe2O4 composite

• A novel technique named simultaneous biosorption and bioaccumulation was very effective in removing arsenic from wastewater.
• This study conveyed the necessity of simultaneous solution of multi-parametric isotherm equations.
• The non-linear isotherm models are more powerful and viable in modelling the adsorption isotherm data.
• Cd2+ and Fe3+ ions exists exhibited positive impact on biosorption/bioaccumulation of arsenic whereas Cu2+, Zn2, Bi3+, Pb2+, Co2+, Ni2+and Cr6+ and SO42− showed negative influence.

The goal of the present study is to design the simultaneous biosorption and bioaccumulation (SBB) batch system for removal of both As(III) and As(V) ions from synthetic wastewater. GAC/MnFe2O4 composite was used as carrier to immobilize arsenic resistant bacteria Bacillus arsenicus MTCC 4380. The surface texture of the adsorbent attached with biofilm was investigated through SEM–EDX analysis. The presence of functional groups on the surface of adsorbent attached with biofilm that may interact with the metal ion was confirmed by FTIR. The biosorption/bioaccumulation of both As(III) and As(V) from wastewater was then examined at varying pH, adsorbent dose, contact time, temperature and initial adsorbate concentration. The minimum contact time to reach equilibrium is about 180 min at pH 7 at 30 °C temperature for both ions. To find the most appropriate correlation for the equilibrium curves utilizing the procedure of the nonlinear regression for curve fitting analysis, isotherm studies were performed for As(III) and As(V) utilizing 30 isotherm models. The pattern of biosorption/bioaccumulation fitted well with Fritz–Schlunder–IV and Fritz–Schlunder–V for As(III) and Brouers–Sotolongo and Fritz–Schlunder–V isotherm models for As(V). D–R isotherm studies indicated that ion-exchange might play a noteworthy role. The effect of co-existing ions for example Cu2+, Zn2+, Bi3+, Cd2+, Fe3+, Pb2+, Co2+, Ni2+, Cr6+ and SO42− at different concentrations were inspected. It is established that the biofilm is very promising for the scavenging of As(III) and As(V) ions from contaminated water sources and therefore may be encourage the use of biofilm in environmental applications. This study brings out the need of simultaneous solution of multi-parametric equations (using relevant software, ORIGIN, in present case) than solution of their linearized forms, which is mostly followed by contemporary investigators.