different water environments models the working principles of microbial fuel cells (MFCs). These devices generate electricity from any sort of domestic, industrial or agricultural wastewater through the action of ‘electrical’ bacteria. The bacteria are restricted in a specific part of the device, the anode chamber, where they spontaneously populate, in the form of a film, the surface of the negative electrode (the anode) during a process called enrichment. At the end of the enrichment, a steady electrical current is generated. This is a consequence of the normal living activities of the electrical bacterial film which, after consuming organic compounds in wastewater as food (the input), is ‘energized’ and releases electrons to produce electricity. If all the operating conditions of the MFC are kept steady, the electricity generated by the MFC can be used as a measure of how happily active the bacteria are with the given food. The higher the level of organics in the wastewater the more electricity is generated. On the other hand, the sudden introduction of a pollutant in the wastewater can disrupt the activity of the bacterial film with a consequent drop in the electricity produced. This enables MFCs to be used as smart devices that sense the presence of pollutants in water in real time.

In the piece, constantly varying waste audio produced by a shortwave radio is introduced as an input. The players respond to the timbre and volume of the input by varying the quality of their sounds to produce a control sound. Periodically additional audio inputs are introduced that differ from the radio input to a greater or lesser degree. The players respond to these sounds by matching their sonic characteristics where they are sufficiently different, altering the control sound.

different water environments was written as part of the LAB NOTES project, funded by South West Crucible. It was made in collaboration with Dr Mirella Di Lorenzo and Jon Chouler from the Department of Chemical Engineering at University of Bath and first performed by Set Ensemble at St. George’s, Bristol on 31 May 2015. The title is taken from a section of Di Lorenzo, M., Thomson, A.R., Schneider, K., Cameron, P.J., Ieropoulos, I., 2014. A small-scale air-cathode microbial fuel cell for on-line monitoring of water quality. Biosens. Bioelectron. 62, 182–188.