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Circularidade de nutrientes em um sistema agroindustrial : composição do bone char, impacto ambiental, e limitações devido à entropia da matéria

Year: 2025
Type: dissertation
Abstract: The increasing demand for natural resources highlights the urgency of adopting practices that promote sustainability. In this context, pyrolysis technology emerges as a viable solution, transforming waste into bone char, which not only contributes to reducing the sanitary risks associated with animal-derived biomass but also enhances soil fertility by serving as a means of carbon storage and nutrient recovery. However, the implementation of nutrient circularity faces significant challenges, particularly in light of the laws of physics and matter. The Earth has a finite amount of matter that is in constant transformation. As matter is utilized, its entropy tends to increase, manifesting as a decrease in nutrient concentration and its dissipation within the terrestrial system. Although the dissipated matter still remains in the system, its potential utility is progressively reduced. Useful matter exhibits characteristics of low entropy, that is, it is ordered, concentrated, available, and capable of meeting the needs of natural and productive processes. In physics, matter with high entropy is commonly associated with disorder and dissipation. Energy can be employed to reorder and concentrate matter in a short period; however, this implies an increase in the energetic entropy of the system. Based on the laws of physics and those governing matter, the limits of nutrient circularity in an agro-industrial system are discussed. Consequently, humanity faces the challenge of preserving the utility of matter without increasing the energetic entropy of the system. In this context, the objective of this thesis is to evaluate the circularity of nutrients in an agro-industrial system and to propose an empirical study on the maximum entropy of matter. Methodologically, the nutrient recovery process for rapid pyrolysis technology was analyzed using the Tukey test. The generation of greenhouse gases per ton of recovered nutrients was accounted for according to the IPCC protocol. Subsequently, the application of the Elemental Flow Analysis method allowed for the quantification of flows and the estimation of the maximum entropy of the recovered matter. The results indicate that nutrient recovery is sanitary safe. Nitrogen, carbon, and chromium decrease as the pyrolysis temperature increases from 450 to 650 °C. Nutrient recovery proves advantageous when associated with the carbon credit market due to the stability of the carbon retained in the char. However, the recovered nutrients represent only 4.23% of the total required for a production cycle and tend to dissipate completely by the seventh subsequent production cycle. The circularity of matter faces entropic challenges that imply a dependence on low-entropy matter for the continuity of production cycles. In this sense, for the circularity of matter to contribute to reducing resource dependence, other nutrient optimization methods may be integrated into the agro-industrial system in order to reduce the entropy of matter.
Language: English
Open Access status: green
OpenAlex ID: W7208635228
Cites: 155
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Related to: 10