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

Maha Mehanna, Tomonori Saito, Jingling Yan, Michael Hickner, Xiaoxin Cao, Xia Huang, Bruce E. Logan

Research output: Contribution to journalArticle

188 Scopus citations

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.

Original languageEnglish (US)
Pages (from-to)1114-1120
Number of pages7
JournalEnergy and Environmental Science
Volume3
Issue number8
DOIs
StatePublished - Sep 30 2010

All Science Journal Classification (ASJC) codes

  • Environmental Chemistry
  • Renewable Energy, Sustainability and the Environment
  • Nuclear Energy and Engineering
  • Pollution

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