Application of Reverse Electrodialysis-Forward Osmosis (Red-Fo) Hybrid System to Fertilizer-Producing Industrial Plant for Efficient Water Reuse

Abstract

This study presents an experimental investigation and a parametric analysis of the applicability of agricultural fertigation and power generation using a reverse electrodialysis-forward osmosis (RED-FO) hybrid system with a water stream discharged from a fertilizer-producing plant.  The feasibility of stream dilution for fertigation application is demonstrated when the resulting moderately saline RED effluent is introduced into the FO process as a draw solution. The effect of external load addition, flow velocities variation, and concentration changes of the working solutions on the overall stack internal resistance and thereby RED performance was evaluated. As such, the lowest internal resistance converged to a threshold value of 4.03 Ω, giving the highest gross power density of 2.17 W/m 2 when a flow velocity of 1.18 cm/s, 10 Ω external load, and 0.015M (NH 4 ) 2 SO 4 /1M NaCl solution pair were utilized. The applicability of the RED effluent to a subsequent FO system as a draw solution (DS) was investigated, showing a dilution rate (17%) and a conductivity (1-2 mS/cm of DS) suitable for agricultural fertigation applications.

Keywords: Reverse electrodialysis (RED), Forward osmosis (FO), Blue energy, Water reuse, Agricultural fertigation