Green walls as a novel wastewater treatment option for craft breweries

Abstract

The fermentation industry has experienced significant growth as craft breweries and small wineries and cideries are enjoying increased popularity. These beverage manufacturers are also facing increased regulatory pressure to treat wastewater (WW) prior to discharge to the environment and municipal sewer systems. This research assesses the performance of a green wall system in treating brewery WW by measuring reductions in biochemical oxygen demand (BOD), turbidity, total solids and total nitrogen. The system includes a green wall column with a 35 L sump and a pump that continuously cycles wastewater at an average rate of 3 L/min through the green wall in a batch process. Experimental scenarios included a control with the pump cycling WW between the sump and an empty column and WW cycled through a media filled column, columns with media and biofilm, and the full system including media, plants and biofilm. After 24 h of treatment, the full system achieved 78%, 97% and 63% reductions of BOD, turbidity and total nitrogen, respectively. The net hydraulic residence time within the green wall column was 40 min over the 24 h treatment period. Although, the WW resided in the green wall columns for only 2.8% of the treatment period, the green wall accounted for 50%, 84%, and 94% of the reduction of BOD, turbidity, and total nitrogen. This green wall system has the potential to provide adequate treatment of brewery wastewater prior to discharge to a municipal sewer system or an onsite treatment system.