Characterization of Winery Wastewater for Reuse in California

Abstract

More than thirty percent of the United States is currently in a drought that is expected to have profound social, economic, and environmental impacts. The intensification of drought conditions in southern and western regions of the country has spurred interest in wastewater reuse in agriculture, including in wine production. Presented here is the first data set of its kind to support California growers and vintners in the reuse of treated winery wastewater (WWW). The data provide a detailed description of California WWW, with particular emphasis on salinity, to enable the benefits and risks of land application to be assessed. Monthly samples were obtained over a 20-month period from 18 wineries in Ukiah, Napa, Lodi, King City, and Paso Robles. Samples collected before and after physicochemical and biological treatment were analyzed for pH, electrical conductivity (EC), cation and anion concentrations, specific ultraviolet absorbance (SUVA₂₅₄), dissolved organic carbon (DOC), and biological oxygen demand (BOD₅). The pH of the WWW varied widely (from 3 to 12). Organic parameters (SUVA₂₅₄, DOC, and BOD₅) showed that treatment effectively decreased organic carbon to levels that would not have negative effects on plant growth or soil. Cation concentrations (Na⁺, K⁺, Ca²⁺, Mg²⁺) in WWW were not reduced by treatment. These baseline data confirm that dissolved salts pose a challenge to the reuse of WWW. However, total salinity of the WWW was moderate (mean EC of 1.0 dS/m) and usually below risk thresholds for common winegrape rootstocks and soil salinity hazards. The conditions under which WWW could be recommended as a water management option in California are described.