Recovery of mixed acid and base from wastewater with bipolar membrane electrodialysis-a case study

Abstract

The current study simultaneously examined the treatability of wastewater by electrodialysis unit and recovery of ions removed as acidic/alkaline solutions. With a bipolar membrane electrodialysis process, the removed ions are stored separately in anolyte/catholyte solutions, and then turned into mixed acids and bases. After the treatment of the leachate using the BMED process, the molar concentration of H+ ions in the acidic solution and the OH- ions in the alkaline solution reached up to 0.095 and 0.048M (conditions: 1L wastewater and 1L anolyte/catholyte solutions), respectively. When the ratio of wastewater to initial volume of anolyte and catholyte was 1/4 (1L wastewater and 0.25L anolyte or catholyte solutions) at the end of a 360-min treatment period, 3.8- (from 0.01995 to 0.07586M for [H+]) and 3.98- (from 0.02344 to 0.09333M for [OH-]) times more intense acid and base concentrations were determined, respectively. This demonstrates that the process can be considered as a cleaner technology for the treatability of wastewater by obtaining more concentrated acid and base as recovered material and fewer byproducts.