Performance of microbial desalination cell for salt removal and energy generation using different catholyte solutions

Abstract

Microbial desalination cell (MDC) is a bioelectrochemical process for simultaneous bioelectricity generation, wastewater treatment, and water desalination. The major drawback of MDC improvement is using toxic catholyte solutions which are normally employed in cathode chamber. In this study, the performance of microbial desalination cell using buffer saline solution was investigated for the first time. The obtained results were compared to several low-cost catholyte solutions, including low concentration of phosphate buffer solution (PBS), non-buffer saline solution, and bio-catholyte. All MDC reactors were fed with actual urban wastewater as fuel. Among all examined catholyte solutions, the MDC using bio-catholyte achieved the highest power density of 32.6Wm−3, followed by the MDC using saline buffer catholyte with maximum power density of 29.4Wm−3. Bio-catholyte had also lower internal resistance, and it improved current generation; maximum COD removal and desalination rate were 80% and 0.38g NaClL−1h−1, respectively. On the other hand, in the MDC with buffer saline solution, the COD removal and desalination rate were 73.1% and 0.34g NaClL−1h−1, respectively. In the MDCs using PBS and non-buffer saline solution, maximum power density was 11.1 and 16.3Wm−3, respectively. Based on experimental data, Among the examined catholytes, wastewater as bio-catholyte and saline buffer solution were the desired candidates for MDC scale up, and the most promising point was their being inexpensive alternatives to supplant the costly MDCs catholytes.