Chemicals, Food and Beverage, Industrial, Metals and Mining, Oil and Gas, Water, Water Reuse
Brewing Best Practices for Process Water Treatment
"Wastewater" is likely not your first thought when you grab a beer from the fridge, but have you ever wondered where all the spent grains, hops and yeast go? Since the Clean Water Act of 1972 was passed, breweries have had to meet strict federal and local discharge limits to produce your favorite brews. Ever resilient, they have approached treatment creatively, with an eye toward new technologies and innovation—especially as consumer preferences have altered the market.
Craft and commercial brewers have adopted new technologies that decrease energy use and water consumption, enhance public image and allow for reinvestment in other operational areas—technologies that are applicable across industries. Whether your next batch is already fermenting or you have no brewing experience whatsoever, you can learn from these process water treatment insights, presented how breweries would prefer—in a frothy glass:
Anaerobic Amber Ale
Breweries are leaders in using anaerobic treatment systems, which break down organic materials in the absence of oxygen. The systems screen wastewater to remove solids and residual wastes, like grains, hops and yeast. Water then runs through an equalization preconditioning tank for pH adjustment before being treated in an anaerobic reactor. Anaerobic systems appeal to industry for creating energy savings, reducing sludge output, lowering biochemical and chemical oxygen demands, and producing biogas—a valuable resource that can be repurposed for heating or fuel or sent directly into gas distribution systems after being sweetened and compressed.
Despite the obvious benefits of anaerobic treatment, limitations still exist. These include effluent levels typically above surcharge limits and high suspended solid levels. Surcharge fees can add up quickly and avoiding such dues requires the addition of a solids separation step or additional treatment.
Aerobic treatment, another popular option leveraged by breweries, uses oxygen to decompose organic matter and has the advantage of lower effluent and suspended solid levels. Aerobic systems, such as a membrane bio-reactor, run water through a similar screening operation to remove solids. Solids are then placed into an aeration tank where organics are removed and then processed through a post-aeration step before being discharged.
Some breweries have adopted pre-treatment processes to lower effluent levels and avoid surcharges. Drawbacks of aerobic treatment include demanding space requirements for the equipment, energy intensive blower and sludge pumping processes, and a high presence of sludge that must be disposed.
Advanced Treatment Tripel
Advanced treatment processes such as anaerobic membrane bio-reactors, already popular in other industries, have gained popularity with breweries. These processes are beneficial when production is at a high capacity or when an industry is located in a city with a small or old publicly owned treatment works facility (POTW). Membrane technology has improved greatly. Anaerobic membrane digesters are able to provide 20 to60 days solids retention time without greatly increasing the treatment facility footprint. These systems have a high removal rate with excellent filtrate characteristics, and chemical oxygen demand removal is normally greater than 95 percent.
While this method truly helps to eliminate solids, in some cases facilities will still need additional treatment depending on how process water is used. For some breweries, building a new facility to process water has been a smart investment. In the long run, having a standalone process water facility can save money by producing cleaner water and lowering surcharge fees.
Treatment methods aside, breweries and industry must also decide how to discharge process water. Indirect discharge releases process water to a POTW or municipality through special discharge permits. Surcharge fees are calculated based on effluent flow, biochemical and chemical oxygen demand and solids levels, and occasionally ammonia concentrations. Maximum discharge limits often exist, creating an additional challenge.
Direct discharge is another option involving the release of process water into a water body. Typically, direct discharge requires a National Pollutant Discharge Elimination System permit, and standards are far stricter than indirect discharge methods. Temperature and dissolved oxygen requirements, strict effluent limitations, and a small window for allowable pH levels all factor into the demands of the direct discharge process.
Want more frothy details on process water treatment, check out our webinar: “Advancements in Process Waste Treatment for the Brewing Industry,” featuring CDM Smith's Tim Rynders, PE, a process engineer with more than 12 years experience in water and industrial treatment, and Rick Molongoski, PE, BCEE, vice president and food and beverage sector leader in our Industrial Services Group.