This new method combines actually two types of technology used to produce electricity: a microbial fuel cell and a reverse electrodialysis system. Two methods inefficient because with a yield too low or too high manufacturing cost. But by associating it can overcome the limitations of individual technologies, said Bruce E. Logan, professor of environmental engineering.
Two related technologies
Bacteria in the cell, they consume the products of the fermentation of plant or human waste and produce electrons which form a current in the battery. But it is a relatively inefficient process. The reverse electro-dialysis, allows it to generate electricity directly from the salinity gradient between saltwater and freshwater. This technology, however, demand more membranes, which makes it expensive.
The researchers combined the two approaches to produce a microbial cell electro-dialysis or reverse RCM produces significantly more energy than the single cell bacteria and requires relatively few membranes. To improve system performance, they replaced the sea water with a solution of ammonium bicarbonate which reduces membrane fouling. The authors report that the MRC technology could provide 0.94 kWh of electricity per kilogram of organic matter from wastewater.