The Use of Constructed Wetlands in Winery Process Wastewater Treatment

Heather Shepard, Wine Industry Consultant

Meeting Summary by John Wondolleck, CHMM

Ms Shepard is currently obtaining an advanced engineering degree from UC Davis. Her graduate work involves evaluation of the treatment of winery wastewaters.

Wineries have a unique wastewater treatment problem that is shared with other food processing industries. The wineries produce wastewaters high in biological oxygen demand (BOD) and chemical oxygen demand (COD) twice per year. Wastewaters produced during harvesting/grape crushing and then during bottling can produce a COD of 44,000 milligrams/liter (mg/L) in the wastewater stream. A typical publicly-owned treatment works generally receives wastewater of a COD of about 500 mg/L. The COD loading of the wastewater is highly variable throughout a processing day making treatment by normal methods difficult.

Winery wastewater is high in sugars and phenols from the washing of trucks, tanks, crushing facilities, etc. Wineries have used aerated lagoons, settling ponds, evaporation, and percolation basins for wastewater treatment/disposal. However, much of the wastewater is produced during the cooler and wetter fall and winter months when the use of evaporation for treatment is less effective.

Ms. Shepard has developed a constructed wetlands as one solution to the Winery's problem. She has tested a constructed wetlands in a small contained plot. The plot consists of bullrushes and cattails grown in a pea gravel container. The retention time of the constructed wetlands was 10 days. During the treatment period, the constructed wetlands was capable of reducing COD to less than 60 mg/L (the discharge standard is 30 mg/kg). It was determined that 90 percent of the removal occurred during the first 2 days. Because the variable strength of the winery effluent is an important consideration for wastewater treatment, the wetlands was capable of handling the changes in influent concentrations.