Modelisation and Optimization of a Microbial Desalination Cell System

In this work, we used a hybrid system composed of a Microbial Desalination Cell (MDC). This system allows, at the same time, the treatment of wastewater and the production of electrical energy for the desalination of saltwater. MDC is a cleaning technology used to purify wastewater. This process has been driven by converting organic compounds contained in wastewater into electrical energy through biological, chemical, and electrochemical processes. The produced electrical energy was used to desalinate the saline water. The objective of this work is the desalination or pre-desalination of seawater. For this, we have established a theoretical model consisting of differential equations describing the behavior of this system. Subsequently, we developed a program on MAT-LAB software to simulate and optimized the operation of this system and to promote the production of electrical energy in order to improve the desalination efficiency of the MDC. The theoretical result shows that the electrical current production is maximal when the methanogenic growth rate equal to zero, increases with the increasing of influent substrate concentration and the efficiency of desalination increased with flow rate of saline water.

Comparison of the removal of monovalent and divalent cations in the microbial desalination cell

Microbial desalination cell （MDC） is a promis- ing technology to desalinate water and generate electrical power simultaneously. The objectives of this study were to investigate the desalination performance of monovalent and divalent cations in the MDC, and discuss the effect of ion characteristics, ion concentrations, and electrical characteristics. Mixed salt solutions of NaC1, MgC12, KC1, and CaC12 with the same concentration were used in the desalination chamber to study removal of cations. Results showed that in the mixed salt solutions, the electrodialysis desalination rates of cations were： Ca2＋ 〉 Mg2＋ 〉 Na＋ 〉 K＋. Higher ionic charges and smaller hydrated ionic radii resulted in higher desalination rates of the cations, in which the ionic charge was more important than the hydrated ionic radius. Mixed solutions of NaC1 and MgC12 with different concentrations were used in the desalination chamber to study the effect of ion concentra- tions. Results showed that when ion concentrations ofNa＋ were one-fifth to five times of Mg2~, ion concentration influenced the dialysis more profoundly than electrodia- lysis. With the current densities below a certain value, charge transfer efficiencies became very low and the dialysis was the main process responsible for the desalination. And the phosphate transfer from the anode chamber and potassium transfer from the cathode chamber could balance 1%-3% of the charge transfer in the MDC.