Effects of Conductivity on Performance of a Combined System of Anaerobic Acidification, Forward Osmosis, and a Microbial Fuel Cell

Abstract

In this study, a novel combined system for simultaneous recovery of bioelectricity and water from wastewater was developed by integrating anaerobic acidification and a forward osmosis (FO) membrane with a microbial fuel cell (AAFO-MFC). Conductivity was thought to be an important factor affecting the performance of the AAFO-MFC system. Thus, effects of conductivity on the performance of AAFO-MFC system in treating synthetic wastewater were investigated. The results indicated that a higher conductivity increased the bioelectricity production, owing to a reduction in the internal resistance. However, it resulted in a rapid decrease of FO water flux and a shorter operating time because of a severer membrane fouling. The conductivity had no impact on the water quality of the effluents. The total organic carbon (TOC) and total phosphorus (TP) concentrations in the FO permeate were less than 4 and 0.5 mg·L-1, respectively, at all conductivity levels. However, the rejection of the FO membrane for NH4+-N was lower at all conductivity levels. The optimal comprehensive performance of this system was obtained when the conductivity was maintained at 7-8 mS·cm-1. In this case, the AAFO-MFC system achieved continuous and relatively stable power generation, and the water flux of FO membrane was relatively stable during a long-term operation of approximately 29 days.