Evaluation of a Selective Resin in Loading–Regeneration Cycles for the Removal of Nitrate from Groundwater

Abstract

In this study, adsorption and desorption of nitrate onto a selective resin was investigated in batch and continuous reactors using Shiraz groundwater. Response surface methodology was employed to examine the role of process variables on the regeneration efficiency of the resin. Both first- and second-order polynomial models described the experimental data sufficiently. In addition, the analysis of variance indicated that the volume of NaCl solution and its concentration were significant parameters affecting the regeneration efficiency, whereas pH and contact time have insignificant effects. According to the results of cyclic experiments, it was found that the adsorption capacity of the resin remains constant after seven steps of loading and elution. In addition, a mathematical model which takes into account the dispersion term and mass action isotherm successfully explains the ion exchange dynamics in the fixed-bed column before and after regeneration. Moreover, the adsorption behavior in the fixed-bed reactor can be predicted using the batch experiment results, which is useful for scale-up experiments and designing industrialized treatment process.