Construction and optimization of an iron particle-zeolite packing electrochemical-adsorption system for the simultaneous removal of nitrate and by-products

In this study, an electrochemical-adsorption (ECA) system was constructed by packing iron particles and zeolites between electrodes to simultaneously remove nitrate and its by-products without excessive active chloride accumulation. Response surface methodology (RSM) with Box-Behnken design (BBD) was applied to investigate the effects of independent variables (iron particle, zeolite and current density) and their interaction on the system performance, also determining its optimum working state. The optimal conditions for the amount of iron particles (19.74g) and zeolites (28.19g) as well as the current density (18.72 mA/cm(2)) resulted in a high nitrate removal efficiency of 95% and merely a little ammonia accumulation. Polarized iron particles could provide more reactive sites and increase mass transfer efficiency, thus promoted nitrate reduction and decreased energy consumption. Synergistic effects of electrolysis and zeolite adsorption accelerated ammonium removal by increasing the rate of ion directional migration. The system having low operation costs and no secondary pollution appeared to be an advisable enhancing strategy for removing nitrate and by-products. (C) 2018 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.