Dynamics of a microbial biofilm in a rotating biological contactor for the treatment of winery effluent

Wastewater from wine-related industries is characterised by high variability in COD and pH. Disposal of these effluents with little or no treatment could lead to heavy financial penalties or pollution of soil and water resources. A pilot-scale rotating biological contactor (RBC) was evaluated for the treatment of winery effluent, with specific focus on the biofilms that formed on the RBC discs. On average, the RBC reduced the influent COD of the winery effluent by 23% (from 3 828 mg/l to 2 910 mg/l) and increased the pH by 0.95 units (from 5.77 to 6.13) at an average retention time of 1h. Similar results were obtained during evaluations at a wine-bottling plant where thick active biofilms, containing mostly yeasts, formed on the discs and proved stable and resilient to various physical and chemical shocks.