New Belgium Brewing Co. (Fort Collins, Colo.) reuses much of its process water for evaporative cooling, cleaning, and landscape purposes. On-site digestion by aerobic and anaerobic bacteria to reduce the organic components in process effluent, coupled with a continuous testing program to accurately monitor the most important sources of high organic loadings within the brewery, have been important keys to the brewery’s successful process water treatment and re-use program.
For every barrel of beer produced, an average of eight to 10 barrels of water is consumed. New Belgium Brewing produces one barrel of beer using about four barrels of water, thanks in part to a strong company-wide commitment to resource recovery that includes on-site process water treatment and an ambitious water reuse program.
New Belgium Brewing produced more than 320,000 barrels of beer in 2004, including the breweries flagship brew, Fat Tire Amber Ale. The company strives to meet its high objectives for environmental stewardship, minimizing resource consumption, maximizing energy consumption, and recycling.
In addition to its water reuse program, for example, electricity is generated onsite, fueled by captured methane from the brewery’s process water treatment plant. The on-site generator currently supplies enough electricity to run the brewery’s entire main building for approximately seven hours per day. This off-sets peak demand charges from the local utility grid as well as significantly off-sets a portion of the premium the brewery pays for purchasing grid-supplied wind power, a decision it made in 1999 to reduce its carbon dioxide production by approximately 1,800 metric tons a year.
New Belgium Brewing initiated on-site process water treatment in 2002 in an effort to minimize the strength and volume of water discharged to the City of Fort Collins’ wastewater collection system and, through re-use, to further reduce the amount of water required to produce each barrel of beer. The existing treatment facility (currently under expansion) has a rated capacity of 80,000 gallons/day. Average daily flows in 2004 were 58,274 gallons, and the plant’s total outlet flow for the year was about 20 million gallons.
The automated process water treatment plant, supplied by German systems provider Von Nordenskjöld, includes a three-stage anaerobic digester, an aerobic lagoon, a biofilter and an aeration pond. Anaerobic treatment is followed by aerobic post-treatment, with anaerobic digestion taking care of approximately 80 percent of chemical oxygen demand (COD) removal and aerobic digestion providing finishing treatment.
High Organic Loadings
As in all breweries, most of the organic content of New Belgium’s effluent is derived from the wort extraction process, wort residues in by-products and wort and beer losses during subsequent processing. Autolyzed yeast from the fermentation process also contributes significantly to organic loadings in the process water effluent. Through anaerobic digestion, the bacteria in wort and spent yeast breaks down simple sugars and starches and convert them to methane gas.
The organic loading of the process water effluent is significantly high, due to the brewery’s low water usage ratio. Whereas a typical brewery’s process water effluent has an average biological oxygen demand (BOD) of less than 3,000 mg/L, New Belgium Brewery’s process water effluent averages 7,500 mg/L.
COD Monitoring Critical
Although high organic loadings are ideal for anaerobic digestion and the subsequent production of methane for fuel, it demands continuous water analysis to monitor the treatment process and aid in process control. The major aim of the testing is to measure COD and other parameters at scheduled intervals to provide a means to quantify waste strength variability to assist with the brewery’s aggressive process water treatment and waste minimization efforts.
Quality and quantity of process water effluent entering the on-site treatment plant can fluctuate significantly, depending upon the different processes that are taking place within the brewery. Because the five-day incubation period for BOD analysis makes this test too slow to provide timely information for process control purposes, the in-house lab runs scheduled COD analysis at all effluent outlet flumes throughout the brewery. Because COD test results can be obtained in about two hours instead of five days, it gives the brewery a more timely analysis of loadings entering and leaving the treatment plant and provides a timely indication of plant performance, thereby permitting closer process control.