The effects of biofilter on the removal of greenhouse gases at anaerobic digestion plants

This study investigated the removal of gases such as methane (CH4), nitrous oxide (N2O) and ammonia (NH3) from biofilters in nine anaerobic digestion plants in Germany that treat biowaste. The treatment is in form of mechanical pre-treatment, anaerobic digestion followed by a composting with or without intensive aeration. The exhaust gases from the mechanical and anaerobic steps are treated by biofilters. In average, the biofilters removed 30% of total organic carbon (TOC), 50% of non-methane volatile organic carbon (NMVOC) and 51% NH3, whereas N2O concentrations increased by 26%. For CH4 the biofilters had only a small removal effect (6%).