A Study on Short-Process Pretreatment Integrated with Reverse Osmosis Membrane - Electrodialysis for Desalination and Recovery of Acidic Wastewater

Abstract

Near-zero discharge of industrial wastewater is imperative due to severe environmental risk and resource wastage, but current integration process is still unavailable to treat and recycle acidic wastewater efficiently and stably. This study proposes an innovative integrated process coupling submerged membrane filtration with reverse osmosis - electrodialysis (RO-ED) for acidic wastewater treatment and resource recovery. The submerged membrane demonstrated exceptional performance of impurity removal with the effluent of below 0.18 NTU, effectively handling wastewater across diverse turbidity levels and pH values. The permeate flux of submerged membrane remained above 65 Lm-2h-1 at the pressure of 0.20 bar. Moreover, a slight decline trend caused by membrane fouling appeared after 140 hours and then gradually stabilized. The RO-ED process was implemented in the separation and concentration of the permeate after short-process pretreatment. By regulating operating pressure and concentration ratio, the synergistic process achieved 8wt% acid concentration for reuse efficiently. Integration of the short-process pretreatment with RO-ED process optimized the balance between treating efficiency and acid recovery requirements. This innovative process significantly reduced acidic wastewater discharge and pollutant release while providing a feasible and sustainable approach for industrial wastewater valorization.