Winery Wastewater OK for Irrigation
Recent studies from UC Davis confirm potential of winery wastewater as irrigation source
San Rafael, Calif.—As water is expected to become even more costly and scarce in coming years, winery wastewater ponds may soon turn from an unsightly necessity to a helpful source of usable water.
While wineries have been taking advantage of treated municipal wastewater for years, most have not taken full advantage of the wastewater generated from cellar operations. A pair of studies by researchers at the University of California, Davis, confirms winery wastewater is a potential source of irrigation water as long as care is taken to best understand the how the treated wastewater will interact with vineyard soils.
Maya Beulow, a researcher with the UC Davis department of Land, Air and Water Resources, said she organized two studies associated with winery wastewater as part of her master’s thesis. Interested in the ongoing drought and growth of the U.S. wine industry, Beulow said she wanted to contribute some research about exploring reusing water.
In her study, published in the American Journal of Enology and Viticulture and funded by the Kearney Foundation of Soil Science, Beulow and co-authors Kerri Steenwerth, Lucas Silva and Sanjai J. Parikh collected and analyzed samples of untreated and treated wastewater from 18 wineries in Sonoma County and the California cities of Ukiah, Napa, Lodi, King City and Paso Robles each month for nearly two years. The samples were analyzed for pH, electrical conductivity, cation and anion concentrations, specific ultraviolet absorbance, dissolved organic carbon and biological oxygen demand.
The wineries participating in the survey use a variety of treatment systems from basic aeration ponds to complex tertiary treatments that mimic wetlands and activated sludge processes. All of the wastewater was found to be nontoxic for vines, Beulow said.
One potential area of concern, however, is sodium, which gets to the wastewater stream through cleaners and is not removed with wastewater treatments. Beulow said many wineries are switching to potassium-based cleaners to avoid this issue.
Different effects on different soils
A complementary study by Beulow, Steenwerth and Parikh published in Agriculture Water Management examined applying solutions with elevated concentrations of sodium and potassium and applying that on soil columns of Bale fine loam from Napa, Redding gravelly loam from Lodi and San Joaquin loam from Lodi. The Bale is dominated by montmorillonite, the Redding is rich in kaolinite, and the San Joaquin is mostly vermiculite.
Based on the soil study, which was also funded by the Kearney Foundation, the researchers determined that wineries looking to reuse winery wastewater should switch to potassium-based cleaners rather than sodium-based ones. Vermiculite soils appear to be more sensitive to wastewater with high levels of potassium and sodium, but the study also concluded more research was needed on the impact of mineral ion hydraulic conductivity in additional soils to “better understand high risk scenarios” that could arise when irrigating with potassium-rich wastewater.
Beulow said the increasing demands on California’s limited water supply could mean it’s well worth it for wineries to make the investment in time and resources to understand how to best use their wastewater.
For example, using wastewater could lead to salt accumulation in the soil, but that can be treated with additional gypsum amendments. “You just need to have all the parts of the puzzle,” Beulow said. “We really are convinced it’s possible to safely use your wastewater.”
Successful program in Sonoma County
One winery already using winery wastewater is Francis Ford Coppola in Geyserville, Calif., which also participated in the study.
The winery employs a sophisticated membrane bioreactor to treat wastewater from the winery’s elaborate hospitality operations, which include a restaurant and swimming pool. Winery wastewater is treated in ponds.
Director of grower relations Lise Asimont said the company is proud of reusing its wastewater, which she believes is a key part of Coppola’s sustainable certifications. Water from the winery’s wastewater system has been used for irrigation for years. “I definitely think there is potential for more vineyards to be irrigated with it,” she told Wines & Vines. “Our situation is rather unique because the vineyard was established with recycled winery water rather than established with well water and then converted. The quality of the vineyard has been anywhere from good to excellent, and we’ve never encountered salinity issues.”
Some other wineries that use wastewater for irrigation were included in this July 2013 report at winesandvines.com.
Asimont said based on the success of using wastewater irrigation for that vineyard, she’s now planning to use it elsewhere. “We are starting to slowly convert the irrigation source for our northern property, the Virginia Dare Winery estate vineyard, over to recycled winery water as well. This is a year or two away from happening, but our experience with the Francis Ford Coppola Winery estate vineyard has given us a lot of confidence.”
