New guidelines help identify winery wastewater solutions
New research from the CSIRO has identified a series of guidelines to help wineries find better ways to reuse their wastewater – in particular fit-for-purpose irrigation.
Co-funded by the Australian Grape and Wine Authority and CSIRO, and conducted in collaboration with the University of Adelaide, the three-year project was led by Dr Anu Kumar, CSIRO Group Leader – Land and Water Flagship.
As part of its final report, Dr Kumar said the guidelines developed during laboratory, field and glasshouse experiments show evidence-based safe concentrations of potassium and sodium (individually and in combination) and chemical oxygen demand (COD) of winery wastewater for sustainable irrigation.
“Wastewater management associated with wine processing is a critical subject due to potential contamination of soil, groundwater or surface water.
“Regulations for environmental discharges and for recycling or reuse schemes are also becoming increasingly stringent.”
Regulatory demands and market pressures that have seen environmental performance become an important issue in the marketplace were reflected in the large amount of support and interest the project received from wineries.
“Markets and buyers are increasingly imposing formal environmental requirements on suppliers. This has resulted in greater interest and environmental stewardship within the industry.
“Over the past four years, wineries in Barossa, McLaren Vale and the Riverina have provided in-kind support to run field trials and access to their monitoring data – in particular Yalumba, which helped run two paired site trials in the Barossa.
“Use of winery wastewater for growing beneficial crops is also being considered as an alternative option for adding value to general winery practices.”
The most important factor when deciding what to do with wastewater is what its ‘end use’ will be.
“The best choice will include consideration of critical issues such as the quality of the wastewater (for example COD, pH, sodium and potassium levels) and federal or state regulations. Any treatment must be ‘fit for purpose’.”
Dr Kumar said as a result of the research, guideline values were developed for key indicators of winery wastewater quality for on- and off-site disposal.
“We propose that wastewater containing less than 460 mg/L of sodium, 1250 mg/L of potassium and 625+1084 mg/L of sodium plus potassium is safe for application on grapevines.
“However these values should be used as a guide only as they’re dependent on the grapevine variety. We also propose an index called ‘cation ratio of soil structural stability’ (CROSS) is used to assess the effect of sodicity on soil structure.
“We’ve shown that potassium has an effect on soil structure equivalent to half that of sodium.”
Dr Kumar said treatment of wastewater wasn’t essential if it was used as it was produced but if wastewater had to be stored, then treatment was critical.
“The nutrients and organic matter in winery wastewater can be beneficial for crops and may enhance crop growth and yield. However, it can also increase soil salinity and site-specific information is critical for each winery, with the guidelines offering trigger values for minimising the impact of winery wastewater irrigation on soil health.
“Unfortunately, there’s no one solution to winery wastewater management, but the final research report has a range of flow charts with various options for reusing wastewater.
“It’s important to recognise that it’s extremely difficult to develop tools for determining and demonstrating sustainability and sustainability indicators that cover all situations.”
The guideline values developed in this project are already being implemented by the wineries that partnered in conducting the investigations.
The research team is also working with AGWA to further share their findings through road shows, fact sheets and seminars.