Enhancing microbial desalination cell performance through co-culture optimization and response surface methodology (RSM) in high saltwater feed concentration

In response to contemporary water and energy supply challenges, the Microbial Desalination Cell (MDC) emerged as an innovative solution, generating electricity and desalting saline water through wastewater treatment. However, the accumulation of ions during the desalination process adversely affects the biocatalyst performance, imposing scalability limitations on the technology. This study focused on enhancing the system's performance by co-culturing Shewanella oneidensis MR–1 and Escherichia coli. Through the response surface methodology, the effects of organic matter concentration and saltwater feed salinity were systematically investigated by central composite design. The study emphasizes the significant impact of studied factors on system performance. Elevated sodium lactate, sodium acetate concentrations, and salinity positively influence the desalination rate, with NaCl concentration showing an interaction effect with lactate. Positive linear relationships for OCV are observed with lactate and acetate. All factors significantly impact power output, with lactate having the most potent positive effect. Additionally, positive contributions to COD removal are noted for lactate and NaCl concentration and a positive interaction effect. These achievements facilitated the development of a mathematical model to optimize system performance by leveraging co-cultured inoculum and strategic environmental manipulation, overcoming limitations from ion accumulation, and opening the path for further advancements in this field.