From Beer to Nuts: Recovering Energy from Brewery Waste Streams with Anaerobic Membrane Bioreactors

CDM Smith, New Belgium Brewing Company and GE Water collaboratively evaluated the effectiveness, reliability, and robustness of a submerged anaerobic membrane bioreactor (AnMBR) technology at the Fort Collins, Colorado craft brewery in the fall and winter of 2014/15. The pilot study driver was the performance limitations of Upflow Anaerobic Sludge Blanket (UASB) digesters, the current leading pretreatment technology for brewery wastewater. While effective in removing (65-85%) of soluble COD, UASBs are limited in ability to handle and remove TSS and other brewery waste flows such as trub, spent spent hops, and spent spent yeast. Additionally, the chemical oxygen demand (COD) and total suspended solids (TSS) in the effluent from UASBs are typically above POTW surcharge discharge limits resulting in additional levied surcharge costs or the need for downstream aerobic treatment. With changes in consumer preferences resulting in a higher percentage of spent hops being used in the brewing process, UASBs and other conventional brewery pre-treatment systems have been unable to fully digest their waste streams due to spent hops-related microbial inhibition impacts to the biota. This market shift has also forced breweries to haul and dispose of more solids at landfills. This pilot study sought to find a more dependable and sustainable solution for treatment of brewery waste. The primary study results indicate the following:AnMBR technology is effective at treating brewery process wastewater and spent spent hops and spent spent yeast residuals.System Design parameters (e.g., membrane flux, digester temperature, organic loading rate, and scour and mixing rates) to generate stable membrane and bioprocess performance.The membrane effluent is able to reliably meet and/or exceed typical industrial pre-treatment effluent requirements for TSS and COD concentrations.Assess the ease of operation and maintenance of the equipment and associated processes.Digestibility of problematic brewery residual waste streams and resulting changes to anticipate in biogas generation and biogas quality.The pilot was operated for approximately 7 months at the Fort Collins-based existing Process Water Treatment Plant (PWTP). The influent feed to the digester was a slipstream connection downstream of the 600 m3 equalization basin which is directly upstream of the existing acidification basin and UASB digester.