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Beer is made from barley, hops, yeast and water. To brew beer, start by germinating barley grain, then stop the germination by roasting the grain. The toasted product is called malted barley.

Second, the malted barley is milled to crack and expose the white starch inside the grain. Third, the cracked grain is added to hot water to liberate the enzymes that convert starch to sugars in the mash. Fourth, the liquid wort (pronounced wert) is filtered from the grain.

Fifth, the wort is boiled, and hops are added at different intervals: early for bitterness and later for flavor. Finally, cool down the wort and add yeast to ferment the sugars into alcohol and carbon dioxide.

After fermentation, carefully siphon the beer out of the fermenter to separate it from the dead yeast and sediments at the bottom of the tank called trub (pronounced “troob” from German; or trub — like pub — in English). Then the beer can then be aged and packaged in kegs, cans, or bottles.

Brewery waste

As a proportion of total wastewater treated by the City of Bend, breweries contribute only 2.1% by volume to the City of Bend Water Reclamation Facility (WRF).

The Beverage Waste Management Program Report for 2019 showed results from measurements at 24 facilities. The biggest brewery in Bend, Deschutes Brewery, contributed 1% of the total influent volume and all other breweries combined represented 1.1%.

The solids and soluble material contained in the wastewater from breweries that must be processed is also modest — representing 11.54% of the total incoming load with 4.22% from Deschutes Brewery and 7.33% from all the others.

According to Christina Davenport, the Bend’s program manager for the Industrial Pretreatment Program, the city protects the WRF by regulating extra strength wastewater from entering the system. In other words, if a business discharges wastewater that has more pollutants than a typical household, then the business is billed an extra strength charge (ESC) for cleaning their more concentrated wastewater.

This incentivizes breweries to “side-stream,” or segregate and process the strongest waste, so that it does not enter the WRF.

Most of the breweries in Bend do side-streaming, which extends the life of the city sewage infrastructure and saves a brewery money by avoiding ESC fees.

Davenport talks positively about the cooperation she gets from the breweries and says, “They are trying to be green and they willingly cooperate.”

What to do with the waste?

One of the by-products created when making beer are the spent grains, which can be fed to livestock or can be dried and milled to make flour for bakery products like up-cycled nutrition bars.

Use of spent brewing grains could grow by creating a dried flour for bakeries and other entrepreneurs to use as a low-carbohydrate, high-fiber food ingredient. For example, Portland-based Take Two Foods makes a barley milk that tastes and behaves like traditional dairy milk.

Davenport says, “We do not have a problem disposing of spent grain in Bend. Farmers would like more to feed their cattle. The concern is high strength liquid wastes: wort, trub and yeast. The default option is to use these resources for fertilizer, compost and soil amendments.”

Treatment systems for the future

Deschutes Brewery investigated its own on-site system to pretreat wastes. The pilot system, tested in 2017, was an anaerobic digester for production of biogas. Unfortunately, the plan is on hold for now, partly because of industry trends and partly because of economics.

Nevertheless, plans and ideas have been percolating for years on how to develop a collaborative system for biogas generation using organic wastes from five major sources of fuel — breweries, FOG (fats-oils-grease), dairy, food and the contents of septic tanks and portable toilets. An analysis of the various alternatives is needed to decide how to proceed.

In an overview of uses for brewery by-products from British craft breweries, a small urban operation reported that all spent grain, yeast and hops were devoted for use in an anaerobic digester. It allowed them to dispose of grain, hops, trub and yeast in the same containers, allowing for one pick-up, one relationship, and one invoice. It was a contractual relationship where the brewery paid a deposit for the bins and a collection fee when they ordered a pickup.

Partners could invest in an anaerobic digester for creation of biogas from organic waste products. The income stream might subsidize the collection system to encourage partners to participate at a lower cost. Existing collection companies could be contracted to collect waste materials for delivery to the digester. A feasibility analysis would outline the best way forward.

In most cases, biogas is used as fuel for combustion engines, which convert it to mechanical energy, powering an electric generator to produce electricity. Appropriate electric generators are available in all sizes. The technology is well known, and maintenance is simple.

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Scott Christiansen is an international agronomist with 35 years of experience. He worked for USDA’s Agricultural Research Service and the U.S. Agency for International Development.

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