According to the Brewers Association, we’re in a golden age of beer production, with the U.S. boasting over 4,000 active breweries as of September 2015. However, this increase in production has been accompanied by several high-profile news stories of brewers in trouble with their neighbors because of offensive odors from the brewery’s wastewater treatment system.
Beer manufacturers would undoubtedly prefer not to focus on wastewater, but it is a critical part of doing business, and one that can cause significant disruption if it’s not handled properly, as the following cautionary tale demonstrates. Besides odor complaints from the neighbors, insufficient wastewater treatment can cause permit violations and interruptions in production—both potentially costly outcomes.
A Cautionary Tale
A brewery in Paso Robles, CA, had a crisis last year when their insufficiently aerated and mixed wastewater ponds generated over 40 complaints—some from several miles away—and a violation notice from the local Air Pollution Control District.
Two new wastewater ponds had been built to treat the rinse water from beer production, which contains yeast and grain residue. Although the ponds had aeration, the fine bubble system was underscaled for the application, did not adequately mix the ponds, and couldn’t handle the high Biological Oxygen Demand and Total Suspended Solids loads that are characteristic of beer production wastewater.
Characteristics of Brewery Wastewater: High BOD, Shock Loads
The manufacture of beer is a water-intensive process, with between two and seven barrels of wastewater generated for every barrel of finished product. Approximately 70 percent of the water utilized during the brewing process becomes a wastewater byproduct.
Wastewater generated by a brewery can be pure liquid Biological Oxygen Demand (BOD) from bottling side spillage, or can include solids like spent grain, yeast, and sedimentation waste, which is expressed as Total Suspended Solids, or TSS. (Most solids should be side streamed to remove them from the wastewater treatment process entirely.) The liquid BOD is in the form of alcohol and sugars, plus washwater from the cleaning of floors, equipment, pipes, and vessels. Washwater may contain cleaning chemicals that can disrupt the biological breakdown in a wastewater treatment process. Overall, wastewater from the production of beer is generally highly soluble biodegradable organic compounds and a lot of it: According to the Wisconsin Department of Natural Resources’ Advanced General Wastewater Study Guide, brewery wastewater can have a BOD of 1,000–4,000 mg/L and a TSS from 200–1,000 mg/L. For comparison, typical domestic wastewater has a BOD of 250 mg/L and TSS of 300 mg/L.
In addition, production schedules can vary, making it important for a brewery wastewater system to be capable of adapting to inconsistent flows, with surges in volume and variations in influent strength and temperature.
What Causes Brewery Lagoon Odors?
About 70% of brewery wastewater is treated by municipal wastewater facilities, which often require pretreatment to remove suspended solids, adjust pH, and reduce BOD to acceptable levels. A lagoon can be an ideal solution for beer production wastewater because it is relatively low-maintenance, environmentally friendly, easy to operate, and cost-effective. A lagoon with sufficient capacity can provide flow equalization, coping with peak loads and changes in influent volume, pH, and temperature, as well as removing excessive BOD.
An insufficiently aerated lagoon, however, can be a source of objectionable odors. Without enough aeration to create the dissolved oxygen required to digest the BOD, a lagoon can go septic and malodorous. Without mixing, solids settle to the bottom as sludge, where they digest anaerobically, which is a slow and smelly process. The methane and sulfurous gases generated by lack of aeration and mixing can waft for miles, resulting in complaints and bad PR for a brewery.
The Air Pollution Control District measured levels of hydrogen sulfide gas emitted by the Paso Robles brewery’s lagoons at 0.03 ppm, a level not likely to cause permanent harm, but one that can cause headache, nausea, sore throat, and eye irritation.
Sludge buildup can also decrease treatment time and reduce capacity—critical to a brewery lagoon’s ability to cope with variable loading. For more information see our article on Causes and Effects of Wastewater Lagoon Sludge Explained.
Preventing Brewery Lagoon Odors
After weeks of bad press, visits from regulatory agencies, and $1 million in mitigation costs, the brewery got their odor issue under control. The hassle and expense could likely have been avoided with a properly designed aeration system.
To treat wastewater effectively, a wastewater lagoon requires both aeration and mixing, with enough dissolved oxygen to cope with high BOD and turbulent mixing to keep solids in suspension. Lagoon aeration is the process by which mixing and oxygen combine to create an active aerobic treatment environment, where bacteria and microorganisms naturally break down and metabolize lagoon BOD and lagoon TSS. The effectiveness of a wastewater aeration system depends directly on its ability to both aerate and mix.
As our cautionary tale demonstrates, an improperly scaled fine bubble system alone is not enough to provide treatment and control odors.
The MARS Lagoon Aeration diffuser is ideal for brewery wastewater lagoons because it provides mixing and aeration in a single modular unit. The patented Double Bubble™ technology combines a fine bubble membrane for efficient oxygenation with a course bubble static tube aerator for intense turbulence and mixing to treat the entire water column.
Together, these components allow the MARS diffuser to oxygenate and treat water effectively while still using energy efficiently. The Triplepoint MARS system also features a portable design—each unit has its own weighted legs and is fed air via flexible weighted tubing. With its flexibility in placement, it can be utilized to manage practically any wastewater treatment cell by simply lowering it in from the surface.
Because brewery wastewater has such high BOD, it is not enough to simply aerate. A brewery lagoon aeration system must be designed to provide enough dissolved oxygen and mixing to handle the very high levels of BOD that are typical of beer wastewater. With properly scaled aeration in its wastewater lagoons, a local brewery will be a source of pride to the community instead of a source of odors.