People have long known there is energy in wastewater; extracting it economically is the problem. Startup Cambrian Innovation claims its technology can do it and a brewery and a winery are now using it to clean their wastewater while producing energy.
The company's EcoVolt machine is a shipping container-size reactor that uses microbes to convert dissolved carbon in industrial wastewater into biogas, which can be burned on site for electricity or heat. Its first demonstration unit is running at the Clos du Bois winery in Sonoma county, and last month nearby Bear Republic Brewery in Cloverdale, Calif. flipped the switch on the second system.
Typically, food and beverage businesses remove the organic material in wastewater -- measured as biological oxygen demand (BOD) -- by aerating water with pumps. But that can be an energy-intensive process. The Bear Republic Brewery expects it will be able to eliminate 80 percent to 90 percent of the BOD of its wastewater with the EcoVolt and reuse 10 percent of its water. By burning the biogas, the brewery thinks it can cover 50 percent of its electricity needs.
The return on investment for the brewery is about four years in reduced energy costs, says Cambrian Innovation CEO Matthew Silver who I spoke to at the company’s headquarters in a South Boston startup incubator space. Silver had planned to work in aerospace but became fascinated by advances in biotech and genetic engineering while a research scientist at MIT. Under a NASA grant, he led research into how bioelectric systems could be used to manage water in space. In doing that, he saw the potential for using electrochemically active microbes to clean water in industry. There's plenty of need: About three percent of the U.S. electricity is consumed treating wastewater, and producing one bottle of beer typically results in up to ten times as much in wastewater.
Making biogas from waste has been done for years and is not necessarily high tech. Industrial anaerobic digesters, which often look like farm silos, use naturally occurring bacteria to consume organic material to make biogas, which is siphoned off.
Cambrian Innovation's EcoVolt achieves a similar result but with a different anaerobic process. Its reactor has microbes that consume organic matter as food and deposit electrons directly on a metal electrode. Found in soil, these microbes, sometimes called exoelectrogens or anode-respiring bacteria, are the active component in some types of microbial fuel cells.
The EcoVolt system uses these microbes to produce a flow of electrons from a bacterial-film-covered anode to a cathode. They do this by breaking down organic molecules into hydrogen and carbon dioxide. At the cathode, another set of microbes, with the aid of the electric current, convert the CO2and hydrogen from the first reaction to methane. A byproduct of that reaction is clean water.