Experimental study on co-combustion of domestic garbage and sewage sludge: Evaluation of synergistic effect and thermo-kinetic behavior

A persistent increase in domestic garbage (DG) has become a significant worldwide issue due to its negative impact on the ecosystem. The co-combustion way of DG and sewage sludge (SS) in a garbage incineration plant has been deemed a viable option. The study aims to quantify co-combustion behaviors, interaction effects, and thermo-kinetic properties between DG and SS at isothermal conditions by a thermogravimetric analyzer. The results showed that co-combustion of DG with 20 % SS could boost the combustion performance indices, and exhibit the synergistic effect. In addition, at the various SS blending ratios (10, 20 and 35 %) under an air atmosphere, combustion performance indices gradually decreased with an increased SS blending ratio but the synergistic effects were inhibited with a 35 % SS blending ratio. Coat-Redfern method was used to determine the combustion kinetics and thermodynamic properties. The apparent activation energy in the DG-SS (80 %/20 %) blend exhibited a non-linear relationship but increased proportionally with higher SS blending ratio. The lowest activation energy (34.70 kJ/mol) was obtained at the DG-SS (90 %/10 %) blend. The results suggest that the co-combustion of DG and SS can improve the overall combustion performance with an optimal blending ratio of 20 % SS for the co-combustion application.