The Brewing Process

Each stage of the brewing process produces a varying amount of wastewater. The volume of wastewater streams varies according to production volume and type of beer. Objects in MRBC’s brewhouse (mash tun, brew kettle, whirlpool) undergo a waste rinse after each use cycle, and a weekly caustic clean. Objects in MRBC’s cellar (fermentation and bright tanks) undergo a water rinse after each use cycle and a caustic clean approximately twice monthly. All wastewater streams are collected in a 3,000-gallon wastewater holding tank. Once this holding tank reaches capacity it is then discharged directly into the municipal sewer. Each discharge occurs when the holding tank is expected to overflow. Therefore, the total average daily wastewater discharge from MRBC into the municipal sewer is approximately 8,125 gallons per day.

The MRBC Brewing Process

The brewing process begins with adding purified water and a roasted malt to the mash tun. This mixture is heated between 100-170 degrees Fahrenheit, a process known as mashing. The mashing process activates enzymes which convert the malt's starches into proteins and fermentable sugars. The solution of sugars, proteins, and water is called wort. Once the brewer is satisfied with the wort, the turbulent solution is allowed to settle. Malted grain that has settled to the bottom of the mash tun is then used to filter the wort as it is drained. The brewer may recirculate the drained word back through the settled grain to further filter out solids.

Once the brewer is satisfied with the clarity of the wort it proceeds into the brew kettle. For MRBC, malted grain that remains within the mash tun is removed and collected by a local farm to feed livestock. Once in the brew kettle, the wort is boiled, stopping enzymatic reactions. Hops are added to the wort during this step. Hops are selected according to the brewer's recipe and may be added at different times to affect flavor.

Upon completion of boiling, the wort moves into a whirlpool (centrifuge) for clarification. The whirlpool spins the wort and separates solids through settling. The separated solids (slurry), called turb, contains proteins, hops, and any other residual solids that remain after brewing. This slurry is discharged and collected by a local farm to fertilize crops. As the wort leaves the whirlpool, MRBC cools the solution so that it may be at the proper temperature to continue into fermentation.

Once within fermentation tanks, yeast is added to the wort to metabolize sugars into alcohol and carbon dioxide. Different variables affect fermentation such as type and amount of yeast, temperature of the solution, and detention time of the yeast. MRBC normally ferments their beers from 14 to 16 days. Once fermentation is complete, yeast is collected to be recycled or disposed of.

Fermented beer then continues into a bright tank, where it will be in cold storage until the beer has matured. Here MRBC brewers carefully monitor the beer to ensure the finished flavor is consistent. Once the targeted flavor has been achieved, the finished beer continues to packaging where it may be kegged or canned, finishing the product.