Bacterial batteries: clean energy with dirty water

Wastewater treatment plants consume large quantities of energy, most of which is purchased from the network, even though wastewater contains more energy in chemical form than is required for its own treatment. The energy potential of wastewater can be judiciously exploited by new technologies such as bacterial cells to reduce the energy consumption of treatment plants. These can convert organic matter in wastewater directly into electricity, using bacteria as biocatalysts. This innovative technology has been attracting growing interest since the 2000s, and has great potential to help limit the operating costs of wastewater treatment plants, and even lead to plants with a positive energy balance.

This article presents bacterial cell technology as applied to wastewater treatment in wastewater treatment plants. It discusses the theoretical and practical principles of this technology, and compares its performance with competing technologies. The methodology to be followed, from laboratory to industrial scale, is also presented, outlining the reactor architectures and materials used. Examples of industrial pilots are given, illustrating the different implementation options and the costs involved. Finally, the outlook for this technology is discussed in the context of a new generation of wastewater treatment plants.

At the end of the article, readers will find a table of the notations used.