Brewery Water and Process Water Management: The Golden, Green Opportunity Found in Anaerobic Treatment Solutions

As the number of craft breweries in the United States continues to grow, concerns about input water and spent process water become increasingly prevalent. Many breweries—particularly in drought-stricken regions and in small towns where aging municipal treatment infrastructure is nearing capacity—are implementing strategies around water consumption and process water discharge to avoid business interruption and mitigate supply and cost concerns. It is no surprise that craft brewers, consistent innovators in both product and process, are tackling input water and spent process water management challenges head on, implementing water conservation programs and investing in sustainable process water treatment technologies. Water and process water management challenges continue to present economic and environmental barriers to growth for breweries across the United States. Brewery process water is significantly higher strength than domestic wastewater. Its strength is typically measured in terms of chemical or biochemical oxygen demand (COD or BOD, respectively), the amount of organic content in the process water. The BOD in brewery process water typically averages 6,000 mg of BOD/L but can run up to 20,000 mg/L. These streams overload municipal wastewater treatment facilities, designed around domestic waste strengths of 150–200 mg/L, pushing them to risk violating their National Pollutant Discharge Elimination System (NPDES) permit limits. This risk, combined with increased water scarcity and aging infrastructure, forces municipalities to set high effluent discharge fees and water supply restrictions for their constituents. Escalating effluent costs depress profitability, and limited water supply caps production, preventing breweries from keeping pace with market demand. This puts them at a critical disadvantage in a rapidly growing, highly competitive market. To alleviate these challenges and ensure continued, sustainable growth, breweries of all sizes must be proactive and strategic about water and process water management. Several solutions offer relief. Brewery process water is traditionally treated with aerobic solutions for which energy, operations labor, and sludge disposal are the largest cost drivers. For example, aerobic solutions use 1.5–2.5 kWh of electricity to remove 1 kg of biochemical oxygen demand (BOD). However, high-strength process water streams contain up to 3 kWh of energy per kilogram of BOD, making anaerobic solutions particularly compelling for breweries. Anaerobic treatment solutions, such as Cambrian Innovation’s EcoVolt® Reactor, are net-positive energy generators and achieve high treatment efficiencies (80–90% removal of BOD). They give breweries an economically viable case for onsite treatment and reuse of their process water to hedge against increased water supply and pricing concerns. Biological Alternatives to Municipal Wastewater Treatment Facilities Onsite biological treatment solutions can be split into two categories: aerobic solutions and anaerobic solutions. Both are effective alternatives to centralized municipal solutions. To select a solution that suits their needs, breweries should optimize around two key considerations: • Treatment: address relevant major process water issues (pH, BOD, and solids). • Economics: evaluate total lifecycle cost and overall environmental benefit. Traditional Aerobic Treatment Aerobic treatment involves adding oxygen to process water, facilitating a biological degradation process in which BOD is converted into biomass, carbon dioxide, and water. Breweries typically select from aerobic treatment solutions ranging from simpler treatment ponds to more advanced membrane bioreactors (MBRs) and activated sludge processes. Treatment ponds are a low capital option for treatment. They accomplish low effluent levels, are relatively easy to maintain, and incur relatively low maintenance costs. However, ponds require an enormous physical footprint, have high energy costs, and leave breweries at risk for odor issues while failing to capture the value trapped in brewery process water. E-mail: caviles@cambrianinnovation.com http://dx.doi. org/10.1094/TQ-54-1-0264-01 © 2017 Master Brewers Association of the Americas 42 MBAA TQ vol. 54, no. 1 • 2017 Brewery Water and Process Water Management MBRs and other advanced activated sludge processes require less physical space, treat process water efficiently and consistently, and are typically containerized. However, these solutions produce large volumes of wasted biosolids that require constant disposal, and they are energy intensive. Traditional Anaerobic Treatment Although anaerobic treatment solutions typically require a higher upfront capital investment than their aerobic counterparts, they compete on total lifecycle cost by offering lower operating costs, producing renewable energy, and generating significantly (around 80%) less biosolids. Anaerobic digestion systems efficiently clean process water while producing an energy-rich biogas, which can be converted into electricity and heat with a cogeneration system. Anaerobic treatment proceeds through a diverse microbial community, culminating with methanogenic bacteria, to degrade organics in the process water in carefully designed reactors, simultaneously treating solids and/or BOD in process water while generating biogas. In recent decades, highrate, soluble anaerobic treatment systems have been used extensively to treat industrial process water. Since the introduction of upflow anaerobic sludge blanket reactors in the early 1970s, advances have led to the introduction of other high-rate system designs such as expanded granular sludge blanket reactors and internal circulation reactors. These treatment systems are characterized as suspended growth anaerobic treatment systems and all rely on a delicate balance of reactor hydraulics and the formation of biomass granules to retain active biomass in the reactor and maintain the treatment process. Anaerobic treatment solutions exhibit relatively slow growth of the biomass compared to their aerobic counterparts. However, they also exhibit greater sensitivity to environmental conditions (pH, temperature, volatile fatty acids, ammonium, etc.). When combined with the proper pretreatment and control systems, many solution designs conquer this hurdle. But despite substantial advances, suspended growth anaerobic treatment technologies still suffer from challenges that hinder their widespread adoption in the brewing industry (1,2): 1. Washout of granular biomass can easily occur owing to upsets in process hydraulics or process water composition and loading fluctuations. 2. Anaerobic systems do not effectively treat low levels of BOD, requiring long hydraulic retention times and/or polishing steps to remove residual BOD. 3. High-rate anaerobic systems are generally operator-intensive due to the need for proper environmental conditions. 4. Custom system design typically requires large projects before economies of scale can be recognized. 5. Because of the bacteriostatic behavior of hops, breweries known for using high volumes of hops in the brewing process experience issues with traditional anaerobic treatment technologies. Eager to capitalize on the opportunities presented by anaerobic solutions, some large-scale breweries turn to custom, onsite solutions. High equipment and installation costs coupled with complex and difficult-to-manage microbial communities that require constant oversight by trained operators make these solutions a major pain point for breweries. Additionally, these solutions are not scalable: as a brewery grows, they run the risk of overloading their onsite treatment solution. Leveraging Bioelectrochemical Systems for Enhanced