Integration of Key Bioprocesses in a Biorefinery Model for the Valorization of Pig Manure: A Proposal Based on Bibliometrics

Biorefineries have emerged as crucial elements in the circular economy, offering a sustainable solution for converting residual biomass into diverse valuable bioproducts by integrating various biotechnological pathways. Despite the challenges posed by the scale of animal waste production, biorefineries have demonstrated their ability to overcome these obstacles and unlock the inherent value of these resources. In this work, a comprehensive bibliometric analysis of specialized literature and patents on the valorization of pig manure was conducted. Among the various techniques, anaerobic digestion (AD) emerged as the most promising method for waste valorization, serving as a platform for biorefinery conceptualization. AD enables the segregation of biorefinery streams and exhibits considerable potential for generating a wide array of subproducts. The relationship between production and environmental indices has been established worldwide. This work proposes a conceptual biorefinery model that incorporates relevant biotechnological routes for the identified bioproducts. These include biogas, hydrogen, electricity, microalgae, bioethanol, volatile fatty acids, organic amendments, biofertilizers, and biodiesel. The limitations and advantages of the most significant processes have been duly considered and included in the model.