Characteristics and practical treatment technologies of winery wastewater: A review for wastewater management at small wineries

The wine-making industry drives tourism and rural revitalization in several countries. Meanwhile, winemaking generates wastewater at all production stages, mainly from cleaning of equipment, floors, vessels, and bottles. This review presents a comprehensive analysis with statistical characteristics on the overall quality and generation rate of winery wastewater since 2007, identifies the technologies used by wineries in pilot- and full-scale wastewater treatment systems, and offers insights on practical wastewater treatment at small wineries. The median wastewater generation rate has been reduced to 1.58 L/L-wine, with a weekly peaking factor of 1.6-3.4 and monthly peaking factor of 2.1-2.7. Winery wastewater is acidic and of high organic strength. The organic substances are largely biodegradable and constituent concentrations do not exceed 50% inhibitory levels for biological treatment. However, the small ratios of nitrogen and phosphorus to biochemical oxygen demand indicate substantial needs to supplement nutrients for aerobic biological treatment. The frequency of processes used to pretreat winery wastewater was in the order of sedimentation > coarse screening > equalization > neutralization. The most frequently reported treatment methods were constructed wetland, activated sludge process, membrane bioreactor, and anaerobic digestion. Advanced oxidation processes have been pilot tested for polishing. The best wastewater management practice at small wineries is physical pretreatment, followed by land-based treatment systems. Covered anaerobic lagoons and underground digesters are practicable anaerobic digestion designs to reduce organic loading to land-based treatment systems. Research is needed to develop sufficient design criteria for the best practicable treatment processes and compare land-based treatment systems at pilot and full scales.