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Issue 8, 2010
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Using microbial desalination cells to reduce water salinity prior to reverse osmosis

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Abstract

A microbial desalination cell (MDC) is a new method to reduce the salinity of one solution while generating electrical power from organic matter and bacteria in another (anode) solution. Substantial reductions in the salinity can require much larger volumes of the anode solution than the saline water, but any reduction of salinity will benefit the energy efficiency of a downstream reverse osmosis (RO) desalination system. We investigated here the use of an MDC as an RO pre-treatment method using a new type of air-cathode MDC containing three equally sized chambers. A single cycle of operation using a 1 g L−1 acetate solution reduced the conductivity of salt water (5 g L−1 NaCl) by 43 ± 6%, and produced a maximum power density of 480 mW m−2 with a coulombic efficiency of 68 ± 11%. A higher concentration of acetate (2 g L−1) reduced solution conductivity by 60 ± 7%, and a higher salt concentration (20 g L−1 NaCl) reduced solution conductivity by 50 ± 7%. The use of membranes with increased ion exchange capacities further decreased the solution conductivity by 63 ± 2% (20 g L−1 NaCl). These results demonstrate substantial (43–67%) desalination of water is possible using equal volumes of anode solution and salt water. These results show that MDC treatment could be used to substantially reduce salt concentrations and thus energy demands for downstream RO processing, while at the same time producing electrical power.

Graphical abstract: Using microbial desalination cells to reduce water salinity prior to reverse osmosis

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Supplementary files

Article information


Submitted
02 Feb 2010
Accepted
16 Jun 2010
First published
07 Jul 2010

Energy Environ. Sci., 2010,3, 1114-1120
Article type
Paper

Using microbial desalination cells to reduce water salinity prior to reverse osmosis

M. Mehanna, T. Saito, J. Yan, M. Hickner, X. Cao, X. Huang and B. E. Logan, Energy Environ. Sci., 2010, 3, 1114
DOI: 10.1039/C002307H

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