Progress on Energy-Efficient Desalination, from Microbes
Pennsylvania State University researchers recently designed a desalination device powered by exoelectrogenic bacteria, called a microbial electrodialysis cell (MEDC), according to research published in
Environmental Science & Technology. The device uses three chambers separated by two membranes, which allow bacteria to grow on an anode and consume organic compounds in the water. The MEDC incorporates microbial fuel cells; the team found that applying limited voltage to the bacteria enabled them to produce hydrogen gas as a byproduct of organic consumption. During this process, bacteria release electrons, which push sodium and chloride ions toward the electrodes and through the membranes thus removing sodium and chloride from the water. Twice the voltage used to produce this effect is gained back in the form of hydrogen, which can then be used to create the voltage to power the device—creating a self-sustaining process. Future developments of the technology will likely include the use of excess energy for further desalination steps, like reverse osmosis. The researchers see the potential for this device to be paired with conventional desalination equipment to make this energy-intensive process more efficient.
Published December 30, 2010