Performance of Recirculatory Microbial Desalination Cell-Microbial Electrolysis Cell Coupled System with Different Catholytes

Microbial Desalination Cell-Microbial Electrolysis Cell (MDC-MEC) coupled system, are very important and efficient in several processes including wastewater treatment; heavy metal removal; desalination; and chemical production. The performances of ferricyanide (MDCF) and 100mM potassium phosphate buffer (MDCP100) as catholytes in the MDC were tested over a fed-batch cycle. The MDC systems (MDCF and MDCP100) were coupled with MEC to determine their effect on Pb and Fe removal. The COD removal efficiencies in MDCF, MDCP100, and control 1 were 92.96%, 90.54%, and 89.03% respectively. All the MDC systems were able to achieve a very high Pb2+ and Fe2+ removal efficiency, >90%. A high cathodic reduction potential was reached and maintained by the MDC-MEC systems, enable the reduction of Pb2+ and Fe2+ to Pb and Fe metals, through precipitation at the cathode of the MEC. MDCF had higher current and power densities of 550 mAm-2 and 166.08 mWm-2 respectively than that of MDCP100. More wastewater can be treated in the MDCP100 for ammonium removal in the middle chamber than that of MDCF. Therefore, the volume ratio of COD and NH4Cl removal in the MDC for balanced COD/Ammonium ions removal is a key driving force to the Industrial scale-up of the coupled system.