Estudo do digestato como nutriente para cultivo de microalgas e o impacto da adição da biomassa algal na produção de biogás

Abstract

The increasing demand for clean, renewable energy, combined with the need to utilize residues from various sources, has driven research into biogas production. Microalgae have strong potential for nutrient recovery from wastewater and for biomass generation. This study investigates the cultivation of microalgae using digestate (a byproduct of anaerobic digestion) and the effect of the produced biomass on biogas generation, contributing to a circular and sustainable biogas production process. In this study, Chlorella vulgaris was cultivated in liquid digestate at different concentrations (5%, 25%, 45%, and 65%), and the influence of the resulting biomass on the anaerobic codigestion of cottonseed was evaluated. The cultures were conducted on a small scale, and the biogas generated in batch biodigestion assays was analyzed for volume (eudiometer) and composition (gas chromatography). The addition of microalgal biomass significantly increased the methane content of the biogas, indicating a potential improvement in the fuel’s energetic quality and reinforcing the viability of integrating microalgal cultivation in digestate with anaerobic digestion. Thus, the results demonstrate that digestate can serve as a viable medium for microalgal cultivation and that integrating cultivation with anaerobic digestion is a promising strategy to optimize biogas production.