Turn Sewage into Electricity

I am a huge fan of science fiction and fantasy. I will suspend belief and enjoy the stories, but sometimes it does irk me that base camps are built and entire planets colonized without waste water treatment. Where there are humans there is waste and we need to address that problem in real life if not in stories.

In real life, the military needs to address sewage and other waste water when they set up base camps and have field operations. The largest shipments of supplies sent to the tactical edge in places like Afghanistan and Iraq are water and fuel. So, last month the Cambrian Innovations in partnership with the U.S. Army announced a project to demonstrate BioVolt™, a self-powered wastewater treatment system. They began field tests of an extremely small scale waste water treatment plant at the Naval Surface Warfare Center in Maryland and are evaluating the system for use at forward operating bases and other off-grid locations.

The BioVolt wastewater treatment system is a living, breathing organism, The BioVolt treatment system uses naturally occurring electrically charged bacteria to digest biologic waste, treating wastewater with zero electrical input from the grid for aeration. BioVolt uses a fuel cell powered by the bacteria that convert energy in sewage to electricity – and cleaned the waste water at the same time.

Managing water and wastewater has traditionally been a very energy intensive process. It is reported by New Scientist that 3% of energy consumed in the United States goes to water treatment. BioVolt has the potential to decouple water and energy infrastructure, which can be extremely useful to the Army, disaster relief, and off-grid water treatment and maybe a future where water infrastructure fails us.

BioVolt uses strains of two microbes, Geobacter and Shewanella oneidensis to process the sludge. The proprietary mix of bacteria liberate some electrons as they respire, effectively turning the whole digestion tank 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.

The system is containerized, mobile, and can be easily scaled for expanded capacity with additional units. The demonstration project is sized to treat about 600 gallons a day of sewage and convert it into clean water for at least 15 people at the 40 gallons a day necessary to personal use. Not only does BioVolt generates the electricity to power itself – plus a bit left over for other use.

Traditional waste water treatment systems use bacteria to metabolize the organic material in waste water. At the end of the process, the microbes can make up a third by weight of the leftovers to be disposed of. Before being put in landfill or used as an agricultural amendment, this “microbe cake” or Biosolids as it is known in the industry, needs to be heat-sterilized and chemically treated, which uses a lot of energy and still requires disposal space.

However, sewage sludge contains far more than pure human excrement. Anything that goes down the drain is in the sewage- oil and grease, chemicals, cleaners, etc. In addition, sewage may contain pathogens and pharmaceuticals. People excrete sickness and everything they consume. Sewage can contain it all-bacteria, viruses, synthetic organic chemicals and human waste. Just sterilizing the Biosolids may not be enough.

BioVolt reduces the amount of sludge but may not be effective at removing pharmaceutical contaminants from waste water. A number of other teams are working on their own versions of these cells. In San Diego Orianna Bretschger at the J. Craig Venter Institute, is testing is testing a system that can remove some pharmaceuticals – synthetic oestrogens, and is looking at ways to remove pain relief drugs from waste water. In the future where real life and science fiction come together we may all have our own self-contained and powered waste water treatment plants that recycle water.

Cambrian Innovations currently has the EcoVolt  system on the market. This system used for industry bulk BOD removal at breweries and similar operations removes over 85% of  BOD while producing a high-quality biogas that is over 80% methane. The EcoVolt treatment system also uses electrically charged microorganisms (bacteria) to digest waste.  Through combined heat and power cogeneration, a typical installation will generate net 30-200 kW of power, cutting carbon footprints and turning an environmental liability into a revenue stream. The EcoVolt solution is in use at the Bear Republic brewery in Cloverdale, CA, eliminating thousands of metric tons of CO2 per year