Wetland Treatment Systems for Municipal Wastewater at a Bourbon Distillery and Potential Value of Incorporating Stillage for Water Treatment Enhancement

Highlights A free-water surface treatment wetland was evaluated for water quality improvements. Nitrate-N removal rates in wetlands were 50% to 99%, depending on wetland influent. Nitrate-N removal rates in wetlands were assessed using bourbon whole stillage and found to enhance NO3-N removal. ABSTRACT. The use of constructed treatment wetlands as a secondary treatment method for wastewater effluent from package treatment plants and distillery stillage has the potential to be an innovative, sustainable method for improving water quality. However, the use of constructed wetlands to treat bourbon whole stillage and a distillery bottling facility’s wastewater treatment plant effluent has been limited. Therefore, the objectives of this study were to (1) quantify constructed wetland water quality improvement as a secondary treatment method for a distillery’s municipal wastewater, (2) optimize treatment design to meet wastewater effluent discharge limits, and (3) quantify the potential to enhance constructed treatment wetland nutrient removal using bourbon whole stillage as an additive carbon source. Four free water surface flow treatment wetland mesocosm experiments were completed during the summer of 2023. Denitrifying conditions were measured along with the collection of water quality grab samples over the 10-day experiments. The constructed wetlands removed nitrate-N between 50% and 99%, E. coli up to 99%, and phosphate-P between 61% and 99%, depending on the influent and the period of the growing season. Bourbon whole stillage was found to enhance removal of nutrients when added to the wetlands in combination with the wastewater effluent at small loading rates. Findings support constructed treatment wetlands as a potential mechanism for secondary treatment for distillery wastewater and bourbon stillage as a potential nutrient removal enhancement. Keywords: Mesocosms, Stillage, Wastewater, Wetlands.