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Published online: 19 August 2009 | doi:10.1038/nchina.2009.164

Environmental chemistry: Solving two crises in one go

Anne Pichon

Introduction

© (2009) ACS

Clean water is an invaluable resource and we must manage it carefully as worldwide supply decreases. Seawater is an attractive source for the production of potable water, but current desalination technologies consume large amounts of energy. Now, Xia Huang at Tsinghua University in Beijing and co-workers¹ have modified a microbial fuel cell to desalinate water while generating electricity at the same time.

A typical microbial fuel cell consists of anode and cathode compartments separated by an ion membrane. In the anode compartment, bacteria oxidize organic matter to generate electrons and protons. In the cathode compartment, electrons and protons combine with oxygen to form water. An electric current flows from the anode to the cathode through an external circuit.

In their new device (pictured), the researchers inserted an anion-exchange membrane next to the anode and a cation-exchange membrane next to the cathode. This modification introduces a central compartment within the cell where desalination takes place. Upon production of electricity by the bacteria, sodium and chlorine ions in the middle compartment move into the anode and cathode compartment, respectively.

Using their modified cell, the researchers could remove about 90% of the salt from seawater in one cycle and generate power output of up to 31 W/m³ (based on total reactor volume). Although the performance on both counts is as yet insufficient for practical applications, the approach shows great potential for solving water and energy problems.

The authors of this work are from:
State Key Joint Laboratory of Environment Simulation and Pollution Control, Department of Environmental Science and Engineering, Tsinghua University, Beijing, China; Engineering Environmental Institute, Penn State University, University Park, Pennsylvania, USA.

Reference

1. Cao, X. et al. A new method for water desalination using microbial desalination cells. Environ. Sci. Technol. doi:10.1021/es901950j (2009). | Article |