Seawater desalination using the microbial electrolysis desalination and chemical-production cell with monovalent selective cation exchange membrane

The objective of this study was to investigate the feasibility of seawater desalination using the microbial electrolysis desalination and chemical-production cell (MEDCC) with monovalent selective cation exchange membrane (MSCEM) (MEDCC-MSCEM). With dissolved aquarium sea salts as artificial seawater, the maximum current density in the MEDCC-MSCEM reached 19.6 ± 0.3 A/m2, which was 43.1% higher than that in the MEDCC with cation exchange membrane (i.e., the traditional MEDCC as the control). The desalination efficiency within 24 h was 76 ± 7% in the MEDCC-MSCEM. The harvested acids (mainly HCl and H2SO4) and alkali (NaOH with 96% purity) concentrations reached 0.28 ± 0.02 and 0.26 ± 0.02 M, respectively. The total energy consumption within 24 h was much lower in the MEDCC-MSCEM than in the control (3.46 ± 0.41 vs. 4.99 ± 0.46 kWh/kg·TDS). The separation efficiency of Na+:Ca2+ and Na+:Mg2+ in the MSCEM was in the range of 42% - 72% and 53% - 87%, respectively. Effective limitation of Ca2+ and Mg2+ by MSCEM resulted in low precipitation of Ca (OH)2 and Mg(OH)2 in the membrane and cathode, which significantly improved the performance of MEDCC. The MEDCC-MSCEM has great potential in seawater desalination with resource recovery.