A study on short-process pretreatment integrated with a reverse osmosis membrane-electrodialysis for desalination and recovery of acidic wastewater

Abstract

Near-zero discharge of industrial wastewater is imperative due to the severe environmental risk and resource wastage, but a 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 in impurity removal, with the effluent below 0.18 NTU, effectively handling wastewater across diverse turbidity levels and pH values. The permeate flux of the submerged membrane remained above 65 L m⁻² h⁻¹ at a pressure of 0.20 bar. Moreover, a slight declining 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 the operating pressure and concentration ratio, the synergistic process achieved 8 wt% acid concentration for reuse efficiently. Integration of the short-process pretreatment with the RO-ED process optimized the balance between treatment 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.