Co-oxidation of domestic garbage (DG) and sewage sludge (SS) was proposed as an effective approach for both treating municipal solid waste (MSW) for environmental safety and recovering energy. Up to now, the thermal co-oxidation behavior of DG and SS was unclear. This study investigated the co-oxidation synergistic effect and thermal behavior of DG and SS under isothermal and non-isothermal conditions by the thermogravimetric analyzer. In addition, calculate the synergistic effect, ignition index, and combustion index for the isothermal and no-isothermal conditions.

Firstly, the addition of SS with DG in increasing blends (10, 20, and 35%) under isothermal conditions with a heating rate of 20 K/min in the same atmosphere (N₂/O₂) was evaluated. Secondly, the blends of DG80/SS20% were analyzed under an isothermal heating rate of 20 K/min with increased O2 concentrations (5, 10, and 20%) in the N₂/O₂ atmosphere. Finally, the blends of DG80/ SS20% were analyzed under non-isothermal heating rates of 10, 20, and 30 K/min under the same atmosphere. The results showed that in the first condition, with increasing blends of SS, the mass loss, ignition index, and combustion index decreased. In the second condition, under an isothermal heating rate with increased O₂ concentration, the mass loss, ignition index, and combustion index were increased. Finally, in the case of non-isothermal conditions, the mass loss, ignition index, and combustion index were decreased.