Biotech plus wastewater equals free energy

A Boston startup is generating energy from food and beverage manufacturing effluent, while also cleaning the water.

Yeast and hops are key ingredients in your favorite beer, but they also ferment downstream problems for brewers and wastewater treatment plants. Organic elements in brewery wastewater are oxygen-hungry pollutants that put considerable strain on wastewater treatment facilities.

Peter Kruger, brewmaster at Northern California's Bear Republic, knows this firsthand. "Like a lot of breweries, we have had phenomenal growth over last 10 years. It's been gradual, but we've switched from a brew pub mentality to that of a larger manufacturer -- one that makes substantial demands on public utilities," he says.

The brewery, which saw 40 percent growth for each of the past four years, felt those demands in the form of surcharges from the municipal treatment plant based on the wastewater's high biochemical oxygen demand (BOD), something the U.S. Environmental Protection Agency regulates under the Clean Water Act.

Over time, this became an untenable situation, but rather than adding a conventional aerobic digester to reduce BOD levels before wastewater leaves the plant, Bear Republic is using a new approach from Boston-based Cambrian Innovation. Cambrian has developed technology that essentially unlocks energy from the organic matter in the water, by flowing it through a bioelectric chemical reactor, in which bacteria eat the organic waste and release an electron. The system uses that energy to create an electrical current, which, combined with carbon dioxide in the water, forms methane gas. (The technical term, on which Cambrian built its proprietary approach, is electromethanogenesis.) The methane is then pulled into a combined heat and power system to create electricity and heat water. When all is said and done, the system, called EcoVolt and built into portable cargo containers, creates more energy than it consumes.

Cambrian grew out of a NASA-funded project that sought ways to treat wastewater in space. Founder Matthew Silver pursued funding while earning his PhD in engineering systems from the Massachusetts Institute of Technology (MIT). Since 2006, he has attracted enough funding to grow the company to a team of 20 and advance the use of bioelectricy to treat wastewater while also generating energy. "Organics in wastewater actually contain a lot of energy. So if you can use the right technology, you can tap into that," Silver says.

The water coming out of the EcoVolt is 80 percent to 90 percent free of pollutants. That is plenty clean enough to send to the municipal wastewater plant, but to reuse the water, Bear Republic will need to first run it through a reverse osmosis system. Kruger's first goal is to replace the plant's air-cooled chillers, which are major energy hogs during summer, with water-based chillers using reused water from the EcoVolt. The company will also divert some water into irrigation and use some for washing down floors. 

Eventually, Bear Republic might reuse 100 percent of the water expelled by the EcoVolt. But Kruger says this is not a foregone conclusion, for two reasons. First: addressing public perception and concerns around drinking beer made with reused water, despite its purity, might pose some challenges. Second: the costs of running all of the water through a reverse osmosis system might be prohibitively costly, compared to simply using municipal water.

Another benefit of the Cambrian installation: Bear Republic uses a considerable amount of hot water, so the combined heat and power system will cut its hot water costs by 30 percent.

Cambrian is targeting EcoVolt at the food and beverage industry because it "has a critical need" for onsite wastewater treatment. California's Clos du Bois winery and Lagunitas brewery are also customers. But Silver says the underlying bioelectric technology could be used, in combination with additional treatment systems, to clean industrial wastewater. Eventually, Cambrian hopes to grow its capacity to treat municipal wastewater. "We're working with the U.S. Army, looking at a system that could do distributed treatment," Silver says.

Laura Shenkar, founder and principal of consulting firm Artemis Water Strategy, says companies such as Cambrian are well poised for a future in which companies will face more urgent needs to address both water and energy use. In 2012, Artemis named Cambrian Innovation to its annual Top 50 list of promising startups in the water technology sector.

"Investing in ways of making water go further is important, but the dysfunction is that water is almost free in terms of inputs for manufacturing," she says.

That's not likely to remain so in the future, especially in water-poor regions or those, like California, sometimes faced with deep droughts. Shenkar says as water becomes scarcer, and energy efficiency and greenhouse gas reduction become increasingly important to businesses, we will see more and more people adopting technology that simultaneously treats wastewater while generating energy.

This post was originally published on Smartplanet.com

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