Infrastructure for irrigation of grapevines with diluted winery wastewater in a field experiment

Abstract

Winemaking produces large volumes of poor quality water. The possibility to re-use this water for vineyard irrigation was investigated in a field trial. For this purpose, winery wastewater had to be diluted to chemical oxygen demand (COD) levels ranging between 100 and 3 000 mg/ℓ. The relatively simple infrastructure and procedure required to dilute the winery wastewater in 15 m³ tanks are described. Analyses of the diluted winery wastewater confirmed that the COD concentrations were reasonably close to the target values. Furthermore, measuring COD concentrations in the irrigation water while it was being pumped from the tanks confirmed that the concentrations of diluted wastewater within the tanks were fairly homogeneous, and that effective mixing had taken place while tanks were being filled. The COD measurements were more reliable when the oxidation time was standardised at 2 h compared to shorter periods, irrespective of the level of COD in the water. After initial practical problems and sources of error were eliminated, the accuracy of treatment application obtained in terms of the target COD concentrations was acceptable.