Insights into an emerging and bioenergy-producing desalination technology: Microbial desalination cells (MDCs)

The microbial desalination cell (MDC) is a recently discovered desalination technology driven by the electrochemical gradient generated from the exoelectrogenic microbial degradation of organic matter. It has gained interest largely because of its self-sufficiency: it is capable of simultaneously desalinating salty water, treating wastewater, and generating electricity. Over the years, several studies have intensely researched MDCs, resulting in a plethora of MDC technologies available in literature. In this review, we cover the progress of the MDC technology, propose a comprehensive classification of MDCs, formulate a new parameter (termed the MDC desalination index), (re)introduce a dimensionless parameter (termed here as the MDC input ratio), systematically assess the performance of MDCs, and synthesize our findings to generate insights into this budding technology. Essentially, this work provides an integrated toolbox for researchers to better understand MDCs and thus improve MDC studies going forward. Lastly, aspects that must be addressed to successfully advance this technology from concept to maturity are discussed. • Steps to advance MDC technology and research for a circular economy are suggested. • A comprehensive classification of MDCs is proposed for adequate MDC categorization. • A new parameter (MDC desalination index) is introduced for assessing MDCs. • Detailed analyses of the desalination performance of MDCs are carried out. • MDCs are renewable, but cannot yet be described as sustainable.