An Annual and Seasonal Characterisation of Winery Effluent in South Africa

Abstract

Winery effluent is known to have a high chemical oxygen demand (COD) and a low pH. In this study, we extensively analysed effluent from two cellars and studied the temporal changes over the duration of a harvest and the duration of a year. We found that ethanol contributes approximately 85% to 90% of the COD of raw winery effluent, with acetic acid being the next significant contributor. The pH showed some dependence on the concentration of acetic acid. The concentration of sodium in the effluent is strongly dependent on the cleaning regime in place at the cellar, and the concentration of potassium has been shown to be linked to the spillage of juice, wine or lees. The data and correlations presented here could allow for an artificial effluent to be prepared easily for research purposes.

Seasonal Variation in Composition of Winery Wastewater in the Breede River Valley with Respect to Classical Water Quality Parameters

“…1A). In annual dynamics monitored at two wineries in Stellenbosch, winery wastewater pH also was lower during harvest (Sheridan et al, 2011). Similar results were reported by Kumar et al (2006).…”

“…A similar seasonal trend was reported for winery wastewater in Australia (Arienzo et al, 2009a). These trends were confirmed where the effluent of two wineries was monitored frequently (Sheridan et al, 2011). Considering the legal requirements for irrigation water quality in South Africa (Department of Water Affairs & Forestry, 1996; Department of Water Affairs, 2013), the results of the survey confirmed that the majority of South African wineries cannot irrigate crops beneficially as part of the General Authorisations for irrigation with winery wastewater unless the water is first subjected to an effective form of pre-treatment, or unless there is relaxation of the General Authorisations.…”

“…Reported COD values in a survey of ten different wineries across South Africa ranged from 3 370 mg/L for a winery in Paarl to 47 024 mg/L for a winery in the Olifants River region (Mulidzi et al, 2009). Sheridan et al (2011) reported much lower COD values for a cellar in Stellenbosch, which peaked at c. 3 800 mg/L. Lower COD values tended to occur in the pre-and post-harvest periods.…”

“…The lower pH was probably due to the organic acids in grapes (Mosse et al, 2011), which could have spilled into the washwater during the winemaking process. Furthermore, ethanol in the wine is degraded to acetic acid, which could further reduce the pH (Sheridan et al, 2011). Since the pH in grape juice and wine ranges from 3 to 4 (Sheridan et al, 2011), juice and wine spills could also have reduced the wastewater pH.…”

“…Furthermore, ethanol in the wine is degraded to acetic acid, which could further reduce the pH (Sheridan et al, 2011). Since the pH in grape juice and wine ranges from 3 to 4 (Sheridan et al, 2011), juice and wine spills could also have reduced the wastewater pH. In a study observing the composition of winery wastewater from ten different wineries across South Africa, pH in winery wastewater during harvest was frequently below 4 (Mulidzi et al, 2009).…”