Avaliação econômica da produção de celulase por fermentação em estado sólido

Abstract

Currently, technological advancements and the pursuit of more sustainable production methods have driven the development of various methodologies that ensure the reuse of raw materials or conscious disposal. One example is the production of second-generation ethanol (E2G), which aims to utilize agricultural and industrial residues, such as sugarcane straw and bagasse, byproducts of first-generation ethanol (E1G) production. Ethanol production via cellulose fermentation requires the separation of cellulose from other components present in lignocellulosic biomass, such as hemicellulose and lignin. Subsequently, cellulose hydrolysis is carried out to generate glucose, with the two main pathways being chemical and enzymatic hydrolysis. The enzymatic route is preferred due to its advantages, such as lower glucose degradation rates, reduced formation of inhibitory byproducts, and higher yields, although it comes with high costs associated with cellulolytic enzymes, making the process economically challenging. A promising alternative to reduce enzyme costs is the use of Solid-State Cultivation (SSC), where thermophilic fungi produce cellulases in packed bed bioreactors. In this context, Gouveia (2021) proposed an innovative industrial method to produce cellulolytic enzymes, integrating key steps such as inoculum preparation, inoculation, and transport to the E1G plant. The proposal aims to reduce costs by sharing infrastructure and processes with the first-generation ethanol plant. This study sought to assess the economic feasibility of Gouveia's proposed project by sizing the necessary equipment and using the CAPCOST software to calculate economic indicators such as NPV, ROI, and payback period. The results demonstrated that, despite the innovations, the project faces significant economic challenges. The installation costs of the equipment and the limited yields of the enzymes — which hydrolyze only 10% of the available biomass — make the process unviable at the proposed scale, presenting an unfavorable economic return. In light of these challenges, it becomes evident that further research is needed to optimize enzyme production, either by increasing the efficiency of the SSC process or by seeking new methods to reduce costs. Thus, improvements in the enzymatic activity of the produced cellulases and in plant efficiency could contribute to economically viable projects and enable large-scale implementation.