McManis Family Vineyards is located on 40 acres of rural land near Ripon, California. The winery produces nine different varietals from grapes grown on its 3,600 acres of vineyards, and the owners are now into their fifth generation of grape growers and winemakers. Certified California Sustainable Winery, McManis meets specific requirements that are verified by an annual third-party audit. Since 2016, McManis has been a Lodi Rules certified vineyard, a designation that confirms responsibility and sustainability through six main standards, one of which is water management.
The McManis Vineyard does not have access to city water or wastewater facilities and is therefore responsible for the management and proper treatment of its own process wastewater. Good agricultural practices and regulations prevent wineries from returning process wastewater to land because, due to its high sugar content, winery wastewater would quickly deplete soil oxygen and oxygen sources. water and harm the cultivation of the vine and the ecosystem as a whole. Instead, wineries most often send their wastewater to treatment ponds, where through the passive, natural process of solar evaporation, pure water vapor returns to the atmosphere.
When grapes are crushed to extract juice upon receipt (prior to fermentation), the resulting waste includes grape solids such as leaves, seeds, pulp, stems, and skins. If not removed, they can significantly increase the quantity and quality of sludge directed to the treatment pond. As previously described, these high-sugar biosolids discourage the evaporation process and decrease pond capacity, ultimately leading to more frequent and costly sludge disposal.
For wineries, grape solids make up more than half of the total Biological Oxygen Demand (BOD) load of the entire wastewater system and are therefore the main target for wastewater cleaning of process. BOD is a measure of the amount of oxygen needed to remove organic waste from water through the process of decomposition by aerobic bacteria. The higher the BOD of the wastewater, the more energy is needed to clean it. Water in a treatment pond with an abundance of sludge must be biologically treated with aeration and chemicals, which creates expense, increases energy consumption and has an impact on the environment.
Dynamic screens provide solutions: more efficiency, less energy
Both the environment and the cellar benefit from water that is as muddy as possible at the entrance to the basins.
In 2005, the vineyard used a rotating drum screen to separate grape solids from process wastewater to prevent it from contributing to sludge in the pond.
“We just weren’t happy with the performance,” said Mike Robustelli, winemaker. “He didn’t do a good job of clearing solids, and he was unreliable. We’ve had a lot of downtime, a lot of clogging, and lots of times the equipment was inoperable. We wanted to improve on this, and after the 2005 harvest, we found the Duperon FlexRake Fine Screen.
The FlexRake Fine Screen provides a T-shaped Wedgewire screen that can screen 0.020 to 0.125 inches. It uses little power and adapts to a range of known conditions and unpredictable variations in debris and throughput, which is useful in a vineyard, where throughput depends on both crop volume and weather conditions. . At McManis, the FlexRake also manages stormwater runoff from 40 acres of surrounding vineyards using a flexible gate system that can be deployed during a rainfall event.
In 2019, McManis Family Vineyards winery installed a second screen to handle increased wine production while continuing to meet water conservation and sludge reduction goals. This addition was accompanied by improvements to the treatment basins and aeration systems to compensate for the increased flow. At 18 feet deep, the two treatment wastewater ponds – each holding two million gallons – use aerobic digestion for the upper layer and anaerobic digestion for the lower layer. Aerobic digestion is facilitated by several brush aerators (a 30 HP aerator and a 15 HP aerator in one basin, and a 15 HP aerator in the second basin). A third pond, which can hold four million gallons, is reserved exclusively for stormwater runoff.
Screens deliver stunning results
All water on site comes from the winery’s own well system. As regional droughts continue to reach historic levels, water conservation is a top priority. Since replacing the rotating drum screen with the FlexRake fine screen, which uses no water spray, the winery uses significantly less water to treat its process wastewater.
With primary screening, a large percentage of grape solids are removed and composted on site, resulting in significant cost and environmental benefits. Theoretically, a fine screen system can save 3,000 gallons of water per day compared to an equivalent rotary drum system. Additionally, the composted solids become a valuable soil amendment applied to the McManis vineyard or sold to other users. And in compost, the high waste sugar content is an asset rather than a liability because it increases bacterial growth to speed up decomposition.
“The benefits are multiple,” Robustelli said. “We’re saving water, creating compost, reducing the energy needed to keep ponds healthy and extending the time between pond cleanings – from every two or three years before screens to every five to seven years with the screens.”
By better removing solids from the grapes during primary screening, McManis minimizes the sludge that ends up in its processing pond. This translates into cost savings in the form of reduced energy demand and water consumption, reduced pond treatment and less frequent dredging. These cost savings also have positive impacts on the environment, with the added environmental benefits of more efficient return of water vapor to the environment, lower BOD for the pond, and soil amendment. ready-to-use soil that doesn’t need to be For McManis, switching to the FlexRake fine screen has allowed the winery to meet a wide range of business and sustainability goals.
Steve Aiken is Regional Sales Manager for Duperon Corporation. Duperon is the leader in simple and adaptive screening technologies and provides solutions for coarse screening, fine screening, low throughput screening, ultra screening, washing, compaction and transport.