Application of central composite design approach for optimisation of zinc removal from aqueous solution using a Flow-by fixed bed bioelectrochemical reactor

Abstract

A flow-by fixed bed bioelectrochemical reactor was used for zinc removal from an aqueous solution. Response surface methodology (RSM) based on central composite design (CDD) was employed to study the effect of process parameters, such as applied voltage, initial zinc concentration, and pH, on the efficiency of zinc removal. To predict the relationship between the response of zinc removal efficiency (RE%) and its independent variables and to maximise this response, a quadratic model equation was established. The reliability of the quadratic model was confirmed by the high R2 value (98.61%). The optimisation study revealed that the initial concentration of zinc was the most effective parameter in the zinc removal process because of its highest F-statistic value (331.59). Using RSM, the optimum conditions for maximum zinc removal were an applied voltage of 1.8 V, an initial zinc concentration of 15.9 mg/L, and a pH of 7.6. With these conditions, a high zinc RE% (90.5%) could be achieved at a specific energy consumption of 0.65 kWh/kg Zn with cathodic current efficiency of 99%.