Promotional roles of ion-exchange membrane in electrochemical latrine wastewater treatment

Abstract

Ion-exchange membrane is usually considered as an undesired component of electrolysis cell, as it increases the internal resistance and causes energy loss. In this study, we investigated the roles of ionic exchange membrane in electrochem. latrine wastewater treatment. The wastewater was treated in anodic chamber, which is sepd. from cathodic chamber filled with Na_2SO_4 electrolyte by cation exchange membrane (CEM). The specific energy consumption for the removal of COD and ammonia can be reduced 51 and 87%, resp. More than 50% of Ammonia could be recovered at the cathodic chamber. Pure hydrogen gas can be collected from the cathodic chamber as well. We demonstrated that the hydrogen can be utilized by hydrogen fuel cell to produce electricity. The hydrogen energy could compensate 20% of the overall energy cost. The anodic effluent of CEM assisted electrolysis cell was further treated in the cathodic chamber of an anion exchange membrane (AEM) assisted cell. Phosphate could be recovered from the latrine wastewater in this step. The proposed two-step membrane electrolysis processes is an example of using electrochem. technique to link the water-food-energy nexus.