Treating Winery Wastewater Without Ponds
Wineries traditionally treat their wine process wastewater with aerobic (aerated) ponds to biologically degrade the biochemical oxygen demand (BOD). The treated wastewater from these ponds needs to have a BOD of 40 ppm or less (depending on the location of the winery) before the winery can discharge the water to the vineyards for irrigation. The discharge level of 40 ppm as well as the restriction of standing water in an irrigation field is regional dependent and is regulated by the Regional Water Quality Control Board (RWQCB) or the local County Department of Environmental Health. If the BOD is allowed to exceed the limits, the irrigation water can create an odor in the pond and irrigated fields, which is offensive to the wineries’ customers and neighbors. If the discharge levels are significantly higher than 40 ppm BOD, the irrigation water can develop a slime layer just under the soils surface, which ‘plugs’ the field. This slime layer blocks the soil percolation of the water into the soil, creating standing water. Most wineries wastewater permits specifically state that no standing water is allowed from process water that is used for irrigation.