Effect of batch vs. continuous mode of operation on microbial desalination cell performance treating municipal wastewater

Abstract

Microbial desalination cells (MDCs) have great potential as a cost-effective and green technology for simultaneous water desalination, organic matter removal and energy production. The aim of this study was to compare the performance of a MDC under batch and continuous feeding conditions. Hence, power and current output, coulombic efficiency, electron harvest rate, desalination rate and COD removal were calculated during the operation. According to the obtained results, the MDC performance exhibited some changes when the reactor switched from batch to continuous mode. The continuously operated MDC indicated a maximum power density of 15.9 W.m^-3 and an average salt removal rate of 80%. In comparison, the batch MDC demonstrated the maximum power density and average salt removal rate of 13.9 W.m^-3 and 68.1%, respectively. In addition, 83.7% of COD was removed in the continuously fed MDC at a hydraulic retention time of two days, which was 13.8% more than amount of COD removed in MDC under a two days batch process. The obtained results revealed that enrichment of anolyte under controlled continuous feeding conditions would relatively improve the MDC performance.