LAUSR

This is the first study that identifies nitrogen loss and drier liquor parameters in a full scale sludge drying facility. Obtained data enabled proposing novel treatment based on deammonification process that allows not only nitrogen removal from drier liquor but also from gravity thickeners supernatant, the stream that is considered too cold for deammonification. The novel treatment approach is compared with nitrification/denitrification in activated sludge process in terms of greenhouse gas emissions. The nitrogen loss during drying was calculated based on two independent methods using full scale data from a long-term measurement campaign. According to results, 9.8-11.2% of nitrogen from dewatered sludge, or 4.9-5.5 g N/kg of TS, was vaporized during drying and then was captured through the purification of process air in drier liquor. Overall, over 40 tN/a from drier liquor and 77 tN/a from gravity thickeners supernatant is recirculated to the activated sludge process and results in the additional emission of 670 426 kg CO2e/a when nitrification/denitrification is applied. That can be lowered by 398 858 kgCO2e/a when the novel approach is considered.