Effects of Brewery Wastewater on Treatment Plants
During the past decade, the number of microbreweries has increased substantially in Michigan. While the product and the employment created by these microbreweries can be a boon to a small community, wastewater from the brewing process and brewery equipment cleaning can cause problems for wastewater treatment plants.
Wastewater from breweries can contain highly elevated levels of BOD5, suspended solids, ammonia, and phosphorus. The wastewater can include rinse water from brewing vessels along with other more thorough cleaning processes. The BOD5 component in the wastewater comes from the sugars, grains, and yeasts used in the brewing process. The phosphorus is likely contained in products used to clean bottles, kegs, brewing vessels, and floors. Unless the brewery has specialized procedures and tanks for handling wastewater, most of the waste is washed into the municipal sewer.
Smaller wastewater treatment plants may have trouble dealing with the high strength wastewater, potentially causing a permit violation.
Although the wastewater volume may not be problematic, the high strength waste can contribute a significant share of a treatment plant’s overall organic load.
It is not uncommon for a brewery's wastewater to contain a concentration of BOD5 more than 20 times stronger than wastewater from a home. Phosphorus concentrations can be 5 to 10 times more than domestic wastewater. At these concentrations, a moderate amount of wastewater volume can contain a large portion of a treatment plant’s organic load.
For example, in one small community, a microbrewery’s wastewater comprised about 3% of the total influent volume to the treatment plant but more than 40% of its organic load. The high organic load taxed the treatment plant’s aeration system making compliance with the discharge permit challenging.
In addition to increasing aeration requirements and the resulting electrical power costs, the high organic load also increased the plant’s sludge production and triggered high strength wastewater surcharges to the brewery.
Modifying Wastewater Strength from Microbreweries
It may be possible to reduce the wastewater strength from microbrewery facilities. A reduction in the wastewater strength has the advantage of reducing the loading on the municipal treatment plant and potentially reducing high-strength wastewater surcharges to the brewery.
Some of these measures may be easy for the brewery to implement and others, such as installing pretreatment systems may have a significant cost.
It is important to meet with the operators of the brewery and help them understand the effect of their wastewater discharges on the treatment system. Similarly, it is important that treatment plant operators understand the nature of the processes and the obstacles that the brewery may have in reducing their waste strength.
Sometimes, modification of cleaning procedures or use of alternative cleaning compounds can reduce loading to the plant. Another alternative may be diversion of the high strength waste to holding tanks and transporting it to another treatment facility with capacity to handle the waste.