RESUMO
RESUMO Atualmente, um dos grandes problemas enfrentados pelos gestores de resíduos sólidos urbanos (RSU) é a disposição final dos resíduos gerados por sua população. As disposições de resíduos devem ser feitas em espaços e sob condições adequados de modo a minimizar os impactos socioeconômicos e ambientais. Nesse contexto, este artigo teve por objetivo estimar o potencial de recuperação energética de RSU usando modelos de simulação matemática para a biodigestão anaeróbia e a incineração. Como objeto de estudo, foram considerados os resíduos dispostos no aterro sanitário de Caieiras, localizado no município de Caieiras (SP). Para avaliação da biodigestão anaeróbia, foram analisados modelos matemáticos que permitem estimar a produção de metano em função dos diversos fatores que interferem no processo (concentração de acetato e de micro-organismos, variação do pH, entre outros). No caso da incineração, foram considerados modelos matemáticos empíricos (baseados nas análises imediata, gravimétrica e elementar) para estimar o poder calorífico inferior dos RSU. De acordo com os resultados obtidos, para a biodigestão anaeróbia seria possível obter potência média de 38,8 MW. Caso a incineração fosse adotada como método de tratamento dos RSU, seria possível obter potência elétrica média de 214 MW (considerando a incineração de 100% dos resíduos). Com base nas simulações realizadas para a biodigestão anaeróbia e a incineração como possíveis métodos de destinação dos RSU, conclui-se que o processo de incineração apresenta potencial de geração de eletricidade aproximadamente cinco vezes maior do que a conversão energética da biodigestão anaeróbia.
ABSTRACT Currently, one of the major problems faced by managers of solid urban waste is the final disposal of the waste generated by their population. Waste disposals should be done in spaces and/or under appropriate conditions, in order to minimize socioeconomic and environmental impacts. In this context, this article aims at estimating the energy recovery potential of urban solid waste using mathematical simulation models for anaerobic biodigestion and incineration. As object of study, the waste disposed in Caieiras landfill, located in the city of Caieiras/SP, was considered. To evaluate the anaerobic digestion, mathematical models were used to estimate methane production as function of the various factors that influence the process (acetate and microorganisms concentration, pH variation among others). In the case of incineration, empirical mathematical models (based on immediate, gravimetric and elementary analysis) were used to estimate the lower heating value of urban solid waste. According to the results obtained, it would be possible to obtain an average power of 38.8 MW for anaerobic digestion. If the incineration method was adopted, it would be possible to obtain an average electrical power of 214 MW (considering the total incineration of the waste). Based on the simulations carried out for anaerobic biodigestion and incineration as possible methods of municipal solid waste disposal, it is concluded that the incineration process of municipal solid waste presents a greater potential of electricity generation, approximately five times higher than the energy conversion potential of anaerobic digestion.
RESUMO
Brazil has an increasing production of municipal solid waste that, allied to the current waste management system, makes the search for alternatives of energy recovery essential. Thus, this work aims to study the incineration of municipal solid waste and the electricity production through steam cycles evaluating the influence of municipal solid waste composition. Several scenarios were studied, in which it was assumed that some fractions of municipal solid waste were removed previously. The municipal solid waste generated in Santo André city, São Paulo State, Brazil, was adopted for this study. Simulation results showed that the removal of organic matter and inert components impacts advantageously on the cycle performance, improving their parameters in some cases; in addition, there is the possibility of reusing the separated fractions. The separation of some recyclables, as plastic material, showed disadvantages by the reduction in the electricity generation potential owing to the high calorific value of plastics. Despite the high energy content of them, there are other possible considerations on this subject, because some plastics have a better recovery potential by recycling.
