Investigation of Modified Microbial Desalination Cell Performance in Sweetening of Saltwater



Gholizadeh A¹ ; Neshat AA¹ ; Pakravan F² ; Miri M³ ; Taghavi M⁴ ; Nikoonahad A⁵
Source: Journal of Babol University of Medical Sciences Published:2018

Abstract

BACKGROUND AND OBJECTIVE: Lack of enough fresh water is a global challenge. Water sweetening can be done using thermal or membrane systems that each of them requires significant energy. Microbial desalination cell (MDC) is a new technology which can desalinate water, generate electricity, and simultaneously purify wastewaters in a reactor. However, low current generation and deionization are from main challenges of this process. This study aimed to improve the MDCs efficacy. METHODS: In this experimental study, a modified three-cell MDC consisted of anode, cathode, and middle chambers, was designed in order to water desalination (20 g/L NaCl). Here, the cathode solution was diffused via ozone (O3-MDC) and the middle saline solution was pretreated into an ultrasonic bath. Subsequently, the results achieved in O3-MDC in terms of water desalination and current generation were compared against those of another reactor operated under oxygen diffusion (O2-MDC), and without ultrasonic pretreatment (control). Biofilm formation on anode surface and dominant bacteria in the O3-MDC reactor were studied using Scanning Electron Microscopy (SEM), and 16S rRNA gene sequencing, respectively. FINDINGS: Saltwater pre-treatment caused to increase the electrical conductivity from 28.1 ms/cm to 35.5 ms/cm; and then current generation from 191 to 131 mV after 24 hr operation. O2-MDC and O3-MDC were able to remove 74% and 55.58% of NaCl from water, respectively. Proteobacteria, firmicuites and acidobacteria were dominant microbial communities in the anode biofilm based on 16S rRNA sequencing. CONCLUSION: Based on the results of this study, modified MDC with ozone and ultrasound waves could be an appropriate option for desalinating salt water. © 2018, Babol University of Medical Sciences. All rights reserved.