New insights into the application of microbial desalination cells for desalination and bioelectricity generation

Abstract

HIGHLIGHTS  Ion behavior of three different salt solutions was studied in identical microbial desalination cells (MDCs).  Mg 2+ , Ca 2+ , and PO4 3were major ions resulting in scaling on cation exchange membrane.  Inorganic deposition and biofouling were more dominant on anion exchange membrane.  Back diffusion of K + from catholyte to liquid under desalination reduced MDC performance. GRAPHICAL ABSTRACT Increasing bioelectricity generation will boost the ARTICLE INFO ABSTRACT Article history:Microbial desalination cell (MDC) is considered as a cost-effective substitution to the present energy-intensive desalination methods. Transfer of salt ions through ion exchange membranes towards the counter electrodes takes place through the utilization of self-generated bioelectricity and the concentration gradient. Ions transportation is one of the main challenges faced in MDCs to which less attention has been paid during the course of development. Therefore, new insights into the application of MDCs for efficient utilization of the generated bioelectricity for desalination are of high demand. In light of this, the present research thoroughly investigated the behavior of ions transportation and bioelectricity generation in three MDCs using three different salt solutions; NaCl, synthetic and artificial seawater. The findings obtained suggested that the efficiency of ions transportation and fouling behavior were influenced by salt compositions and concentration of the salt solution. Multivalent ions (i.e. Mg 2+ , Ca 2+ , and PO4 3-) were found more prone to precipitation on the CEM forming a scaling layer, whereas, inorganic deposition and biofouling development were more likely to happen on the AEM. This study also confirmed the occurrence of a significant back diffusion of K + from catholyte into desalination chamber. Such back diffusion could limit the use of potassium buffer in catholyte in real-scale applications. Moreover, the coefficients of salt transfer and ion diffusion were calculated using mathematical model and Excel solver in three running MDCs. Low salt transfer and ion diffusion coefficients values obtained for all three MDCs could explain the general low performance of MDCs. Further studies are required to optimize the salt transfer and ion diffusion coefficients to boost MDC performance in general; affecting their real-scale implementation.

Potential of Utilization of Renewable Energy Technologies in Gulf Countries

“…The Middle East, with 2.9% of the world population, possesses 50% of the global seawater desalination production capacity [55]. Currently, thermal and membrane-based methods are the two major commercial types of desalination technologies used in the world [56]. However, both technologies raise environmental concerns: high energy consumption of thermal-based technologies and discharge of concentrated brine back to the environment in the membranebased desalination technique [57].…”

Harnessing exoelectrogens in a novel microbial desalination cell: a study on the impact of salinity on sago effluent treatment and power generation

“…The reason for the increased performance of the mixed culture inoculated MDC – 2 compared to Shewanella putrefaciens -inoculated MDC – 1 is because brackish water contains ions other than sodium and chloride like magnesium, calcium, potassium, phosphate, sulfate and other trace metals and minerals. 42 These ions diffuse through the ion-exchange membrane and combines with the effluent in the anode chamber. Since the microorganisms consider the effluent as its nutrient source, the diffused ions will also have an effect on the microorganisms.…”

Microbial Desalination Cell for Sustainable Water Treatment: A Critical Review

“…-Investigation of ion transportation behavior. [1] -NaCl solution, -Synthetic seawater, -Artificial seawater.…”