Two-Stage Anaerobic Digestion of Sugarcane Vinasse: Alternatives Alkalinizing Strategies and the Role of the Fermentative-Sulfidogenic Process

• Grant number: 23/10733-7
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: July 01, 2025
• End date: March 31, 2028
• Field of knowledge: Engineering - Sanitary Engineering - Environmental Sanitation
• Principal Investigator: Marcelo Zaiat
• Grantee: Renan Coghi Rogeri
• Host Institution: Escola de Engenharia de São Carlos (EESC). Universidade de São Paulo (USP). São Carlos , SP, Brazil
• Associated research grant: 22/10615-1 - Consolidation of the biorefinery concept applied to the biological treatment of wastewater and solid wastes, AP.TEM

Abstract

The two-stage anaerobic digestion (2st-AD) of sugarcane vinasse has been widely studied and applied to potentialize the energy recovery potential of this wastewater. However, the high costs related to the alkalinizing strategies of the methanogenic process are one of the main barriers to the application of this process on the industrial scale. Moreover, the sulfate (SO42-) presence in this wastewater stimulates the sulfidogenic activity and implies many drawbacks for the methanogenic process as competition for the same substrates and sulfide (H2S) generation on the liquid and gaseous phase. On the other hand, when sulfidogenesis is established in the fermentative phase, it can decrease the consumption of alkalizing compounds in the methanogenic process, considering the neutral pH range adequate for both processes. Besides it decreases the competition and inhibition potential and improves the compositional characteristics of the biogas in the methanogenic reactor. However, techno-economic studies indicate the need to adopt alkalinizing strategies that replace the use of chemical compounds for the consolidation and scalability of that configuration in the sugarcane biorefineries. In this context, the present study aims to evaluate alternative alkalinizing strategies for the fermentative-sulfidogenic and methanogenic phases in sugarcane vinasse biodigestion. From the results obtained during the experimental phase, it will be made techno-economic and environmental analysis considering the distinct organic loading processing capacity, energy recovery potential, and compositional characteristics of the biogas. (AU)