Produção de biogás através da digestão anaeróbica de água residual de agroindústrias

Abstract

Due to the development of various agro-industrial activities, a significant amount of organic waste is generated which impacts natural resources. In this context, the growing demand for sustainable energy methods has made methane a highly promising and versatile energy source. One of the most notable approaches to harnessing this energy source is biological production from industrial and domestic waste with a high concentration of organic matter. This practice not only addresses environmental concerns, but also promotes sustainability and contributes to energy security. Within this context, the aim of this study was to evaluate the methane production potential of three agro-industrial effluents - manipueira, whey and vinasse - in batch anaerobic reactors using the anaerobic digestion process. The research aimed to identify the efficiency of each substrate in generating biogas, considering the specific operating conditions of the reactors, with a focus on the feasibility of using this waste as a sustainable source of energy. In this way, the study was organized into four distinct stages: 1) obtaining the substrates - collecting the waste used; 2) characterizing the waste - to evaluate the characteristic variables of the substrates; 3) setting up the batch reactor; 4) physicochemical and chromatographic analyses - relating the effect of the variables through a principal component analysis (PCA). The experiments were carried out at the Environmental Sanitation Laboratory of the Federal University of Alagoas (UFAL) in order to investigate the technical, economic and environmental viability of this approach, considering the efficiency of converting waste into biogas and reducing the environmental impact associated with wastewater treatment. The results showed that the system is effective in converting manipueira, vinasse and whey into biogas and biofertilizer, offering a sustainable solution for waste treatment. Daily methane production was approximately 93.07 mL of CH₄ in Reactor 1 and 141.87 mL of CH₄ in Reactor 2, both fed with manure, after 7 days of operation. For vinasse, Reactor 2 produced 55.12 mL/day, while Reactor 1 generated 16.98 mL/day, also after 7 days of operation. In the case of whey, production was more balanced, with Reactor 1 generating 34.89 mL/day and Reactor 2 generating 28.37 mL/day, after 7 days of operation. These results demonstrate the system's ability to generate renewable energy from different agro-industrial effluents, considering all the reactors operating for the same 7-day period.