Filling in sewage sludge biodrying gaps: Greenhouse gases, volatile organic compounds and odour emissions

[Display omitted] •A complete study of the gaseous emissions from sewage sludge biodrying is presented.•Biodrying reduced the biowaste moisture a 34.3% and increased its LCV a 65.1%.•GHGs emission factor from biodrying was 28.22 kg CO2eq per Mg of initial DM in SS.•An odour emission factor of 3.10E + 07 ou per Mg of initial DM in SS was obtained.•Terpenes, sulphur compounds and ketones were the most abundant VOCs emitted. In the present work, a complete study of the sewage sludge (SS) biodrying technology was conducted at bench-scale, aiming at assessing its performance and providing a valuable insight into the different gaseous emission patterns found for greenhouse gases (GHG) and odorant pollutants. As process key parameters, temperature, specific airflow, dynamic respiration index, final moisture content and Lower Calorific Value (LCV) were evaluated. At the end of the biodrying, a product with a 35.9% moisture content and a LCV of 7.1 MJ·kg−1product was obtained. GHGs emission factor was 28.22 kgCO2eq per Mg of initial mass of dry matter in the SS (DM0-SS). During the biodrying process, maximum odour concentration measured was 3043 ou·m−3 and the estimated odour emission factor of the biological treatment was 3.10E + 07 ou per Mg DM0-SS. Finally, VOCs were completely identified and quantified. The most abundant VOCs found in the biodrying gaseous emissions were terpenes, sulphur-compounds and ketones.