Treatment plants use a lot of energy to do their jobs, and NewScientist (30 July 2016) reports on some recent research progress:
Last month, Boston-based Cambrian Innovation began field tests of what’s known as a microbial fuel cell at the Naval Surface Warfare Center in Maryland. Called BioVolt, in one day it can convert 2250 litres of sewage into enough clean water for at least 15 people. Not only that, it generates the electricity to power itself – plus a bit left over.
This is a big deal, as conventional treatment plants guzzle energy – typically consuming 1.5 kilowatt-hours for every kilogram of pollutants removed. In the US, this amounts to a whopping 3 per cent of the total energy demand. If the plants could be self-powered, recycling our own waste water could become as commonplace as putting a solar panel on a roof.
Why are they called fuel cells?
BioVolt uses strains of Geobacter and another microbe called Shewanella oneidensis to process the sludge. Its proprietary mix of organisms has one key advantage – the bacteria liberate some electrons as they respire, effectively turning the whole set-up into a battery. This has the added benefit of slowing bacterial growth, so that at the end of the process you have electricity and no microbe cake [to be irradiated and disposed of].
While 3% is not a large number in itself, this sort of project, if it can be brought to fruition and implemented on a nationwide, commercial basis, can serve as a model for other industries – an important part of the move away from exorbitant energy use. Reducing costs and emissions – a double barreled approach to saving the country & world.
