WINETECH Technical Yearbook 2019

CAROLYN HOWELL: ARC Infruitec-Nietvoorbij, Stellenbosch KEYWORDS: Treated winery wastewater, New Zealand wineries. MAY 2019 MANAGEMENT AND RE-USE OF TREATED WINERY WASTEWATER (PART 1): NEW ZEALAND WINERIES

Carolyn went to New Zealand to participate in a technical tour focussing on the management and re-use of treated winery wastewater, with particular reference to wine grape irrigation. She reports… The Western Cape is experiencing one of its worst droughts to date. Urban users are currently limited to 105 L of water per person per day and water is a precious, scarce resource. Approximately three years of good rainfall is needed to recover from the drought. This implies that even if the 2018 winter rainfall is normal, the region will still feel the negative consequences for some time thereafter. Therefore, alternative sources of irrigation water for vineyards, e.g. using treated wastewaters, will become more important under the above-mentioned conditions or if climate change reduces long- term winter rainfall.

THE GEOGRAPHY AND CLIMATE OF NEW ZEALAND New Zealand is an island country located approximately 2 200 km from Sydney in the south-western Pacific Ocean. It consists of two main islands, namely the North Island and the South Island separated by the Cook Strait. The climate is mostly temperate, with January and February being the warmest months and July the coldest. Most settled, lowland areas of the country have between 600 and 1 600 mm of rainfall. The west coast of the South Island has the highest rainfall, while the east coast of the South Island and interior basins are the driest. WINERIES VISITED IN THE WAIRARAPA REGION The Wairarapa wine producing region, of which Martinborough is a sub-region, is a

PHOTO 1. The windbreak on the right-hand side where the winery wastewater at Martinborough Vineyard is irrigated. Note that during winter the irrigation line is stored on the vineyard irrigation line. The wastewater irrigation line is purple, as per convention to indicate wastewater.

small grape producing region and produces 1% of New Zealand’s wine grape harvest. Martinborough Vineyard is a small winery in Martinborough where approximately 200 tonnes of grapes are crushed per year. Seventy percent of the grapes crushed at Martinborough Vineyard are Pinot noir. Most

of the wastewater in the winery is generated by cleaning tanks and washing floors. The winery has stopped using sodium hydroxide (NaOH) as a cleaning agent. The wastewater is pumped through a coarse sieve and stored in two 3 000 L underground tanks. With the exception of pH adjustment, the wastewater