Thermal balance analysis of autothermal thermophilic aerobic treatment of human excreta

An energy model for the autothermal thermophilic aerobic treatment (ATAT) of human excreta was developed and validated using a full-scale reactor for quantitative interpretation of the self-heating principle. The results showed that the principal heat source was heat generated from microbial oxidation (Qbio). The specific mean generation rate of Qbio during self-heating was estimated at 1.190 MJ/h/t-5.7 times higher than that after self-heating at 0.208 MJ/h/t. The heating potential of human excreta was estimated on a chemical oxygen demand (COD) basis at 12.1 kJ/g COD. The heat loss from airflow, including sensible heat loss by airflow (Qair) and latent heat loss by evaporation (Qvap), was primarily responsible for the decrease in reactor temperature after self-heating.