Unlocking waste reuse benefits for craft breweries

Mid-sized and large craft brew­eries face a big ob­sta­cle to meet­ing the grow­ing de­mand for their beers: high dis­charge fees for the waste gen­er­ated by the brew­ing process. To avoid ex­pen­sively dis­charg­ing brew­ery wastes like hops, yeast and fatty sed­i­ment, brew­eries can use treat­ment tech­niques like anaer­o­bic di­ges­tion. Not only do these tech­niques save money, they also have the po­ten­tial of gen­er­at­ing bio­gas and re­cy­cled water. Until now, cost and com­plex­ity have de­terred most brew­ers from using these tech­niques, but the ap­pli­ca­tion of new mem­brane tech­nolo­gies en­ter­ing the mar­ket are mak­ing a tastier busi­ness case for anaer­o­bic di­ges­tion.

CDM Smith’s R&D Pro­gram helped fund a pilot study that demon­strated the ben­e­fits of one of these tech­nolo­gies, the anaer­o­bic mem­brane biore­ac­tor (AnMBR). Using an AnMBR for brew­ery process waste re­sulted in more ef­fec­tive treat­ment than in­dus­try-lead­ing al­ter­na­tives, un­lock­ing mul­ti­ple po­ten­tial ben­e­fits for craft breweries.

Col­lab­o­rat­ing to Cross a New Fron­tier

As New Bel­gium Brew­ing, one of the na­tion’s largest craft brew­ers, eyed ex­pan­sion from its Fort Collins, Col­orado head­quar­ters to the thriv­ing beer scene of Asheville, North Car­olina, space con­straints chal­lenged the need to treat the brew­ery wastes that a new fa­cil­ity would gen­er­ate. CDM Smith en­gi­neers be­lieved that an AnMBR treat­ment sys­tem could prove ef­fec­tive by pro­vid­ing ex­cel­lent re­source re­cov­ery on a small foot­print. AnMBR tech­nol­ogy has been used suc­cess­fully in the dairy in­dus­try for sim­i­lar pur­poses. Prov­ing that this tech­nol­ogy could work with brew­ery waste meant cross­ing a new fron­tier.

“Be­cause AnMBR had not been proven in the brew­ing in­dus­try, New Bel­gium wanted to fully vet it be­fore com­mit­ting to it for Asheville,” says CDM Smith discipline leader Tim Ryn­ders, PE. “We pro­posed fund­ing a pilot-scale R&D study to col­lab­o­ra­tively push the lim­its of these new mem­branes and to test if AnMBR could pro­vide New Bel­gium with the right so­lu­tion.”

GE Water & Process Tech­nolo­gies joined the R&D ef­fort, pro­vid­ing its pro­pri­etary mem­branes in kind for the 9-month study, while New Bel­gium staff signed up to lead the op­er­a­tions and data col­lec­tion ac­tiv­i­ties for the pilot.

From Process Waste to Reusable Re­source

Brew­ers have tra­di­tion­ally re­sisted con­ven­tional anaer­o­bic mem­branes be­cause of foul­ing is­sues. “Today’s mem­brane sys­tems are more re­fined,” says Rynders. GE’s AnMBR sys­tem uses hol­low-fiber ultra-filtration membranes submerged inside a process water treatment tank. The process waste­water is con­stantly pumped through the tank at a higher rate than what is filtered.

“The new mem­branes can’t help but hold the solids in the di­ges­tion sys­tem longer, mean­ing that the methanogens, our pre­ferred ‘bugs’ in this sys­tem, had 50 days in­stead of two to get ac­cli­mated to the hops and yeast, chew on it and di­gest it,” says Ryn­ders. “An­other ad­van­tage we found in the AnMBR was im­proved foul­ing con­trol. The con­tin­u­ous pump­ing of the process waste­water into the tank pro­vided cross-flow on the membranes, limiting surface foul­ing. We also used the bio­gas pro­duced from the anaer­o­bic di­ges­tion process to clean the mem­branes.” In all, the AnMBR sys­tem could run con­tin­u­ously for a few months with­out the mem­branes hav­ing to be cleaned.

Be­cause of this longer di­ges­tion pe­riod and mem­brane efficiency, the team saw strong results in the qual­ity of the AnMBR’s effluent, in­clud­ing a 98 to 99 percent chemical oxygen demand (COD) and bi­o­log­i­cal oxy­gen de­mand (BOD) re­moval rate, as well as sig­nif­i­cant re­duc­tions in total sus­pended solids (TSS). By achiev­ing such high-qual­ity effluent output, the team demon­strated that the AnMBR sys­tem also added po­ten­tial for water reuse. “Reusing this effluent to brew beer would require at least a disin­fec­tion process and possibly further ad­vanced treat­ment,” said Ryn­ders, “but even non-potable water could have many ap­pli­ca­tions at a brew­ery and could sig­nif­i­cantly lower water-to-prod­uct ra­tios.”

In ad­di­tion to meet­ing sur­charge lim­its, the pilot study de­liv­ered a 98 per­cent re­cov­ery rate of methane bio­gas emit­ted by the di­ges­tion process, which could be used for heat­ing or truck fleet fueling. “Biogas condi­tion­ing is one of the most interesting parts of this research,” says Ryn­ders. “Every sin­gle brewer, live­stock, dairy and food and bev­er­age com­pany should con­sider AnMBR, be­cause the bio­gas pro­duc­tion of­fers the po­ten­tial to re­duce cap­i­tal in­vest­ment pay­backs and de­crease fos­sil fuel de­pen­dence.”

One of the biggest appeals of R&D projects is that everyone is admitting they aren't the masters. That honesty is important.

Tim Rynders, PE, CDM Smith Discipline Leader –Treatment Process and Piloting

Push­ing the Lim­its

“One of the biggest ap­peals of R&D pro­jects is that every­one is ad­mit­ting they aren’t the mas­ters,” says Ryn­ders. “That hon­esty is im­por­tant. It al­lows us to de­mand more from each other. For ex­am­ple, as we were test­ing the lim­its of the AnMBR ap­proach, I told our GE part­ners we had to push the mem­branes to their break­ing point, oth­er­wise I hadn’t done my job. That’s not some­thing they were used to hear­ing from an en­gi­neer!”

For Ryn­ders, this pro­ject was a chance to ex­pand his hori­zons. “I learned so much work­ing on this pro­ject, feel­ing a dif­fer­ent en­ergy in a dif­fer­ent in­dus­try. The speed and ex­pec­ta­tions were in­tense, so I had to be­come more agile. It opened up a new world of tech­ni­cal chal­lenges and in­sights.”