An annual and seasonal characterisation of winery effuent in South Africa
Winery effuent is known to have a high chemical oxygen demand (COD) and a low pH. In this study, we extensively analysed effuent 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 effuent, with acetic acid being the next signifcant contributor. The pH showed some dependence on the concentration of acetic acid. The concentration of sodium in the effuent 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 artifcial effuent to be prepared easily for research purposes.