Impact of thermal hydrolysis on VFA-based carbon source production from fermentation of sludge and digestate for denitrification: experimentation and upscaling implications
Andrea Carranza Muñoz, Jesper Olsson, Andriy Malovanyy, Christian Baresel, Nethra Machamada-Devaiah, Anna Schnürer
Abstract
) and denitrification rate of 8.74 mg NOx-N/g VSS∙h, indicating a potential for reduced treatment volumes. Calculations based on a full-scale WWTP (Käppala, Stockholm) demonstrated that the carbon sources produced could replace fossil-based methanol and meet the nitrogen effluent limit (6 mg/L) despite their ammonium content. Fermentation of 50-63 % of the available sludge at Käppala WWTP in 2028 could produce enough carbon source to replace methanol, with only an 8-20 % reduction in methane production, depending on the production process. Additionally, digestate production would be sufficient to generate 81 % of the required carbon source while also increasing methane production by 5 % if a portion of the solid residues were recirculated to the digester.