Boulder: Boulder Wastewater Treatment Facility employs cogeneration to reduce power costs

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From the Boulder Weekly (Chelsea Long):

…since 1986, the treatment facility has been finding ways to offset that electrical necessity. Back then, it was methane gas. Now, it’s solar power. “For the last 25 years, we’ve been beneficially using the methane gas that we derive from treated solids. As we break down and treat solids, a gas is formed that’s primarily methane,” Douville says. “Methane has a combustion value, and we use a system called co-generation to make electricity.” That system generates an average of 20 percent of the facility’s power needs, and it keeps methane from being released in the atmosphere. “Not all communities do that. We’re on the exception end of things,” Douville says. “Normally what a facility would do is burn the gas, so they’d flare it, ignite it and combust it, and it would go off in the atmosphere as carbon dioxide and heat. Boulder made the commitment to produce electricity.”[…]

One of the last steps in decontamination is to rid the water of bacteria and other pathogens that are present in high levels. Currently, the center uses gaseous chlorine to disinfect the water of these pathogens. “It’s very effective but is extremely toxic to aquatic life and a huge safety risk to city staff and residents nearby, if we had a leak or tank rupture. That’s a low-probability event, but still a realistic risk scenario that we face,” Douville says. The center uses a second gas to dechlorinate and remove residual chlorine, so that toxins aren’t released into the stream, but both of those gases will be replaced with a UV disinfection system. “It’s a focused, targeted wavelength of high energy that only takes a matter of seconds to disinfect the wastewater and achieve compliance with our regulations,” Douville says.

More wastewater coverage here and here.

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