Systematic Investigation of Microbial Desalination Cells (MDC) Performance under the Impact of Cation Migration Behavior and Multi-cation Interactions in Industrial Wastewater (Supporting Information)

Microbial desalination cells (MDCs) provide a sustainable approach to desalinate saltwater powered by bacterial metabolism during organic oxidation. A systematic study was conducted to clarify the ion-dominated interactions for preventing unpredictable risks for long-term MDC operations in the treatment of complex ion-containing wastewaters. The investigation showed that the migration and unequal scaling of cations at different ion exchange membrane (IEM) surfaces greatly influenced their transmembrane processes, which were directly affected by the hydrolysis and precipitation behavior controlled by the solubility product and ambient solution, resulting in the following removal efficiency of MDCs: Na⁺ > Ca²⁺ > Cu²⁺ > Al³⁺ > Fe³⁺. A further study showed that the precipitation antagonism and pH buffer effect of multiple cations could positively promote the desalination of sparingly soluble cations. Eventually, the desalination efficiency of MDC in the treatment of actual industrial tailwater was maintained at 63.2–74.1 %. These findings not only elucidated the kinetics of ion migration in detail but also offered new application possibilities for MDCs.