By: Becky Garrison
In recent years, Pacific Northwest-based wineries have faced unprecedented water issues as regional droughts continue to deepen and regulations have become stricter in an effort to limit surface and groundwater contamination and promote more sustainable practices. During the Oregon Wine Symposium, held virtually from February 15 to 17, 2022, a session titled Diving Deep Into Winery Water Usage & Treatment offered a summary of this current situation pertaining to water use and how wineries can manage their water use and treat wastewater.
Panel moderator Emily Terrell, associate winemaker for Brittan Vineyards (McMinnville, OR), opened the session with a brief summary of the current state of water use in the Pacific Northwest. A typical winery on the West Coast uses between three to 10 gallons of water per gallon of wine produced.
Regulations regarding water may increase due to municipal handling limits and local standards for discharge. Also, over the past few years, Washington State and California both developed new general permits. These are tiered winery permitting systems, with fees, monitoring, inspection and at least quarterly analysis of water discharged from the winery.
These standards help protect groundwater and surface water based on discharge methods and the specifics of the location. Such standards are necessary as improperly treated wastewater can lead to a host of complications, including:
• Damage to soil and crops
• Kill aquatic life.
• Contaminate surface water and groundwater.
• Degrade infrastructure in municipal treatment plants.
• Overwhelm municipal treatment systems.
In a general sense, the easiest solution to improve winery water use is to use less water. By tracking water use, wineries can see where and how they are using process water, which can help identify ways to become more efficient. Sometimes this is a simple fix, such as adding water-saving spray guns, reducing wine hose diameter or fixing leaky hose manifolds. Reconsidering the way wine lees (the solids remaining after fermentation) are collected and disposed of can also dramatically decrease the volume and energy intensity of the wastewater, including taking advantage of a collection service available in some areas (not Oregon, unfortunately).
Finally, once the wastewater is generated, how can the energy load be lightened downstream? This comes down to neutralizing pH, removing the solids and perhaps adding a digestion step to further deplete the nutrients before discharging into a controlled environment or municipal system. As droughts intensify, some wineries install reclamation systems to treat, digest, filter and reuse all or a portion of their process water.
Treating Wastewater In the Winery
In his presentation, John Haslett, wastewater manager for 12th & Maple Wine Company (Dundee, OR), offered an overview of their winery wastewater treatment process, including the chemicals, equipment and tests involved in this process, which discharges into a small municipal system with strict requirements. The primary wastewater chemicals that he uses are magnesium hydroxide to neutralize the pH and polymer to bind and remove the majority of the solids prior to digestion.
At 12th and Maple Wine Company, they start by mixing and prepping their wastewater in a mixing tank. By running the wastewater through a side screen into their batch tank, they remove all of the large particles and treat it with magnesium hydroxide to neutralize the pH. Then, the water pumps through their Cavitation Air Flotation (CAF) device. The CAF is a long trough with a propellor that makes micro-bubbles, which float all the solids to the top after the polymer sticks them together. Next, the paddles scrape the solids off the top and remove them from the system into a solid waste/compost stream. Flotation removes 90 percent of the BOD, helping the bio system’s ability to digest by reducing process load and filtering solids leaving only dissolved solids for digestion. After that, the clarified water moves to their digestion system for a further reduction in Biological Oxygen Demand (BOD), or the amount of oxygen consumed by bacteria and other microorganisms during digestion under aerobic conditions in a defined period of time. By reducing this energy demand, the winery dramatically reduces the burden on the municipal treatment system downstream and increases the total volume of water it can discharge to the system.
To keep up with the digestion demands of the wastewater stream, Haslett sometimes needs to add bacteria to the system due to changes in the microbe population due to upsets, such as adding or removing nutrients or a rapidly changing pH environment. Among the sources he uses to obtain bacteria are Clearblu and Aquafix. In his presentation, he quoted a statement from Clearblu regarding the types of recommended bacteria used in treating wastewater.
Almost all commercially available bacteria blends only contain Bacillus strains. While Bacillus is an excellent treatment bacteria, it is best suited for treating fats, oils, grasses, and proteins. This is why they are primarily used in wastewater treatment plants. Brewery, winery and food processing waste contains sugars and carbohydrates in very high concentrations. This makes their waste vastly different from sewage treatment plants. The best bacteria for breaking down sugars and carbohydrates are Pseudomonas. Pseudomonas will digest these very effectively and reduce BOD levels far more rapidly.
Historically, Haslett’s digestion system has consisted of a series of aerated holding tanks that the wastewater slowly passes through while undergoing microbial digestion. Recently, he trialed a new system called the BioGill, which consists of a space-efficient square tower filled with a ceramic matrix that pulls oxygen in passively and provides a stable environment for the culture to occupy while the wastewater slowly passes through. These units have been very successful in improving culture health and digestion time. Haslett cited the example of a pH upset, where the BioGills recovered in three days, whereas the old system would have taken approximately three weeks. They have plans to acquire additional BioGill units but are already taking advantage of the BioGill’s ability to seed the culture of the downstream holding tanks, providing for better overall health and an increased capacity for BOD reduction.
Each week, Haslett tests the wastewater using several different tests. After getting the BOD numbers, he converts them into pounds of BOD and pounds of TSS (Total Suspended Solids) and then report this number when required by city and local governmental entities. Haslett’s optimization of the CAF, BioGill and digestion system continue to reduce these numbers, easing the burden on the city and making some water reclamation a not-too-distant goal of the winery.
For smaller wineries with limited financial resources, Haslett stresses that the first priority is to adjust the pH. At the very least, get a small tank to use for holding, adjustment and mixing. A further investment would be a simple screen filter to remove the larger solids before dumping the effluent. He also emphasized that the BioGill is an accessible, low-power technology for smaller wineries looking to reclaim or further reduce their impact on downstream processing resources.
Reducing Processed Water
Bob Coleman, technical winemaker for Treasury Wine Estates (Saint Helena, CA), delved into ways to reduce processed water in the winery. He proposed using in-place or in-line wine treatments to minimize the number of tank movements and, therefore, cleaning and water consumption. This avoids the need for more energy-intensive, solids-removal procedures, such as cold setting, decanters and centrifugation that require tank-to-tank transfers.
To remove solids, this winery is exploring the use of a Jameson Cell. This is a high-intensity froth flotation cell invented for use by the coal industry. While a Jameson Cell can handle wine wastewater, Coleman sees how it can also benefit in reducing water use during wine production. Coleman envisions feeding wine juice in this small set of cells. Air or nitrogen gets entrained in this stream that’s in this downcomer, as they call it. Gas bubbles attach to the solid particles floating them to the top and allows removal as a solid waste stream. The clean juice then goes to the tank and gets inoculated right away.
Also, Coleman references developing protein absorption columns designed for in-place protein removal. These columns have absorption material that will take out heat-unstable proteins. Then, wash out the proteins and reuse the column repeatedly. This process stabilizes the wine and eliminates the need for bentonite – and elimination of bentonite in our waste stream
In addition, Coleman introduced a more efficient cold stabilization process (fluidized bed cold stabilization), a joint project with Professors Roger Boulton and Ron Runnebaum at UC Davis. This in-place cold stabilization process minimizes wine loss and refrigeration needs by using a small, dedicated chiller and counter-current heat exchanger. This avoids lowering the temperature on the main winery refrigeration loop, saving both energy and water. The potassium bitartrate crystals generated in the stabilization process can be reused to form a circular process.
Coleman recommends electropolishing the tanks or purchasing them already electropolished. This keeps solids from attaching to the tank’s surface, thus reducing the water and chemistry to remove bitartrate, grape residue and biofilm stuck to the side of the tanks.
In California, wineries can take advantage of a lees removal service. This involves squeegeeing the lees out of the tanks and putting them into totes, which a service takes away. They can recover bulk wine from it and then send the solids to compost.
Coleman recommends potassium hydroxide over the cheaper sodium hydroxide for the basic wash and potassium bisulfate for the acid wash when assessing cleaning chemicals they use. After use, he suggests running both of these through a nanofilter or semipermeable filter that allows the ions, chemistry and water to pass through while leaving the dirty residue separated. It is possible to reuse the chemistry and water multiple times. After cleaning the tanks, putting these two washes together results in a pH appropriate for wastewater ponds and does not increase BOD or COD.
Hydrogen peroxide at 0.5 percent can be used as a sanitizer, and this is lower than the three percent hydrogen peroxide available at the supermarket. What hydrogen peroxide isn’t used during sanitization will break down into water and oxygen. An onsite hydrogen peroxide generator can produce the amount of sanitizer needed, thus avoiding safety issues when transporting and handling higher concentrations of this chemical.
The smart controls used on the six wastewater ponds allows for data collection. In particular, Coleman highlighted the need to clean the DO (dissolved oxygen) probes so that they can provide accurate feedback. After some exploration, they found cleaning heads that use compressed air to routinely in-place clean the probes. These DO probes trigger aerators when the oxygen drops below a designated threshold. This process control saves energy and increases the health of the ponds.