Multi-objective optimization of waste incineration for minimal carbon monoxide and sulfur dioxide emission and rate maximization: a case study of Mbezi, Mkuranga-Pwani, Tanzania

Incineration is widely employed for hazardous waste disposal, but results in harmful flue gas emissions. This study optimizes a double-chamber incineration process to reduce sulfur dioxide (SO2) and carbon monoxide (CO) emissions while maximizing the incineration rate. The effects of waste mass, primary chamber temperature (PT), and secondary chamber temperature (ST) were analyzed using a full factorial design of 27 experiments. ANOVA revealed that mass had the greatest impact on emissions and incineration time, ST had a moderate effect, and PT had little influence. Regression analysis provided models for incineration time, CO, and SO2 emissions. Single-objective optimization using sequential quadratic programming showed that CO and SO₂ emissions were non-conflicting objectives, with optimal parameters: mass 33 kg, PT 550°C, ST 800°C; maximum incineration rate at 69.2 kg at the same temperatures. NSGA-II was applied for multi-objective optimization, yielding a trade-off at mass 46.1 kg, PT 547.4°C, ST 797.6°C, resulting in CO, SO₂ emissions, and incineration rate of 15,851 mg/m3, 159 mg m-3, and 98.7 kg/h, respectively, corresponding to +20.4%, +34.7%, and -7.4% of the single-objective optima. The findings demonstrate the importance of optimizing incinerator settings to balance between emission reduction and incineration rate.