The city of Boulder, Colo. will have more than a drinking buddy in Avery Brewing Co. if preliminary discussions result in a signed deal.
The city needs to reduce nitrogen levels in its treated wastewater discharges, and after testing, found that a byproduct of beer production called weak wort would solve the problem and save the city money.
The brewer will divert its weak wort byproduct into an onsite 6,000 gallon storage tank, and about twice per week, liquid haulers will transport it all about three miles away to the city’s wastewater treatment plant. The city processes 12,000 million gallons of wastewater per day and uses activated sludge biological nutrient removal (BNR) to treat the liquid waste. In activated BNR, microorganisms thrive on nitrogen in the waste, but they need a good source of carbon to consume higher levels of the pollutant.
In 2014, Boulder tested a few sustainable, biodegradable products, including tofu, but the beer byproduct was the most effective alternative to acetic acid or other standard additives designed for denitrification of wastewater effluent. Full-scale testing showed that the addition of weak wort would reduce nitrogen compounds in the city’s discharges by an additional 20 to 30 percent.
It will also save the city money--some $500 per day, or $52,000 per year.
