Efficient salt removal in a continuously operated upflow microbial desalination cell with an air cathode

Abstract: Microbial desalination cells (MDCs) hold great promise for drinking water production because of potential energy savings during the desalination process. In this study, we developed a continuously operated MDC – upflow microbial desalination cell (UMDC) for the purpose of salt removal. During the 4-month operation, the UMDC constantly removed salts and generated bio-electricity. At a hydraulic retention time (HRT) of 4days (salt solution) and current production of ∼62mA, the UMDC was able to remove more than 99% of NaCl from the salt solution that had an initial salt concentration of 30g total dissolved solids (TDS)/L. In addition, the TDS removal rate was 7.50g TDSL−1 d−1 (salt solution volume) or 5.25g TDSL−1 d−1 (wastewater volume), and the desalinated water met the drinking water standard, in terms of TDS concentration. A high charge transfer efficiency of 98.6% or 81% was achieved at HRT 1 or 4d. The UMDC produced a maximum power density of 30.8W/m3. The phenomena of bipolar electrodialysis and proton transport in the UMDC were discussed. These results demonstrated the potential of the UMDC as either a sole desalination process or a pre-desalination reactor for downstream desalination processes. [ABSTRACT FROM AUTHOR]