Scaling up microbial desalination cell system with a post-aerobic process for simultaneous wastewater treatment and seawater desalination

Abstract

A key challenge in developing microbial desalination cells (MDC) is system scaling up. Herein, a large-scale MDC system (total liquid volume of 105L) was developed and used as a research platform to investigate the issues associated with scaling up. Highly nonuniform performance was observed among the individual MDC modules. Multiple feeding points could enhance current generation through better substrate distribution. Applying an external voltage significantly increased current generation from 670mA (no external voltage) to nearly 2000mA (1.1V applied), with the corresponding increase in salt removal rate from 3.7 to 9.2kgm−3day−1. Energy consumption for salt removal decreased with increasing the applied voltage, but wastewater treatment required more energy at the same time. The high COD input decreased current generation and thus salt removal because of growth of heterotrophic microorganisms on the cathode surface. Reducing catholyte recirculation intensity could greatly decrease energy consumption by 40–60%.