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The process of syngas production through solid waste and biomass co-gasification is a promising and environmentally friendly technology. This study focuses on the processes modeling, parametric and synergistic analysis, multi-objective optimization, and the identification of optimal operating conditions. Model validation compared simulation results with experimental data, demonstrating good agreement, especially for the kinetic model. The study investigates the effects of gasifier temperature, steam-to-feed ratio (S/F) and blending weight ratio (B/W) on tar yield, syngas composition and syngas yield. The results reveal that higher gasifier temperatures increase CO concentrations while decreasing CO2 and CH4 concentrations due to the promotion of endothermic reactions. Syngas yield (GY) notably increases with rising temperatures, whereas tar yield decreases. This is attributed to the higher temperatures enhancing the tar cracking process, converting it into lighter gases. Similarly, higher S/F ratios lead to elevated H2 and CO2 concentrations, enhancing GY and reducing tar yield. Furthermore, varying B/W ratios affect syngas composition, with increased B/W ratios decreasing H2 and CH4 concentrations but increasing CO2 concentrations. However, both GY and tar yield decrease with higher B/W ratios due to less carbon being available to form tar products and converting into syngas. Statistical analysis, including ANOVA and the response surface method (RSM) with Box-Behnken design (BBD), assesses the significance of parameters and optimizes operating conditions to maximize GY and minimize CO2 concentration. The B/W ratio is identified as the most influential factor on GY, while the S/F ratio significantly impacts CO2 concentration. The multi-objective optimization using a genetic algorithm (GA) and TOPSIS method determines the optimal conditions at T = 1099.95 °C, S/F ratio = 0.79, and B/W ratio = 10.02, achieving a GY of 2.672 Nm³/kg, a CO2 concentration of 8.045 vol.% and tar yield 17.0617 g/Nm³. Furthermore, the performance of a CO2 absorption process using CaO. The process has 47.3352 kg of CaO per hour, achieving a CO2 capture efficiency of 93.7967% and a CO2 purity of 99.9992%. This efficient process effectively captures and purifies CO2, suitable for applications requiring high-purity CO2.

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