Modeling hexavalent chromium removal from aqueous systems using a fixed bed of immobilized bacteria and zero-valent...

This study reports on the preparation of a novel biosorbent by combining zero-valent iron nanoparticle (nZVI) and hexavalent chromium (Cr(VI))-tolerant bacteria which was evaluated for removal of Cr(VI) in a fixed-bed continuous-flow system. The nZVI was characterized for its physical characteristics and immobilized along with Cr(VI)-tolerant bacteria within calcium alginate matrix, which was used as the adsorbent in fixed-bed column to remove Cr(VI) from synthetic wastewater. The concentration of Cr(VI) in the effluent of the fixed-bed column was examined by varying the bed height of the column and the flow rate of synthetic wastewater individually. Breakthrough studies were performed, the column performance was analyzed using a general mathematical model, and the Gompertz model to evaluate adsorption kinetics and efficiency. The general model was utilized to analyze the breakthrough data with Bohart-Adams model, Yoon-Nelson model, and Thomas model. General model was found to predict the results better than the Gompertz model. The results demonstrate that this system has significant potential for scaling up, with promising applications at pilot and industrial levels for real-time WW treatment.