Valorização energética de resíduos sólidos urbanos em São Carlos: comparação entre aterro sanitário, digestão anaeróbia e digestão anaeróbia com pré tratamento

Abstract

Advances in international decarbonization targets, such as those established at COP28, reinforce the need for technologies capable of integrating energy generation and environmentally appropriate management of municipal solid waste. In Brazil, methane emissions represent one of the main environmental impacts of the sector. However, when properly captured and converted, methane becomes a strategic renewable energy source. In this context, this study evaluated the energy and environmental potential of valorizing food waste (RA) combined with urban pruning through three technological routes: (i) landfill disposal, (ii) anaerobic digestion (AD), and (iii) AD with thermal pretreatment of pruning, across six different scenarios. Based on previously obtained experimental data and literature parameters, the energy potential and environmental impact of each scenario were estimated, along with a sensitivity analysis. The results showed that AD, especially when combined with pruning pretreatment (Scenario 3), increased the specific biogas yield by approximately 159% compared with landfill disposal (Scenario 1), enabling the generation of up to 1.94 kWh of electricity per cubic meter of biogas and around 104 tons of steam per day. Regarding energy supply, the electricity generated could meet up to 8% of the total electricity demand of the municipality of São Carlos (Scenario 3), while in the same scenario it would be possible to supply approximately 43% of UFSCar’s annual demand, demonstrating the technology’s potential to support relevant institutional loads. From an economic perspective, scenarios that utilized thermal energy presented the highest financial gains, highlighting the relevance of heat recovery in the analyzed routes. From an environmental standpoint, methane capture and conversion made it possible to avoid up to 1.94 tCO₂eq per ton of treated waste (Scenario 3), emphasizing the technology’s potential for climate mitigation. The sensitivity analysis confirmed the robustness of the model and identified the methane fraction as the most influential parameter, with variations of 14% to 20% in the results for 10% increases in its value. Thus, the study demonstrates that anaerobic digestion with thermal pretreatment is a promising alternative for integrating waste management, energy recovery, and circular economy strategies at the municipal level, providing technical support for public policy development and future studies on pretreatments, valorization routes, and digestate applications.