Co-treatment of lignocellulosic waste and sulfate-rich wastewater with generation of molecules of high added value

• Grant number: 21/09463-0
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Effective date (Start): September 01, 2022
• Status: Discontinued
• Field of knowledge: Engineering - Sanitary Engineering - Environmental Sanitation
• Principal Investigator: Marcelo Zaiat
• Grantee: Bárbara Franco Vieira
• Host Institution: Escola de Engenharia de São Carlos (EESC). Universidade de São Paulo (USP). São Carlos , SP, Brazil
• Associated research grant: 15/06246-7 - Biorefinery concept applied to biological wastewater treatment plants: environmental pollution control coupled with material and energy recovery, AP.TEM
• Associated scholarship(s): 23/10377-6 - Use of metals to enhance lignocellulose degradation in a sulfate reduction environment: availability of trace metals and control of sulfide toxicity, BE.EP.PD

Abstract

The generation of lignocellulosic residues is large and growing all over the world, mainly in the agroindustry. The use of this type of by-product as a substrate for the generation and use of biofuels, energy carriers, and carboxylic acids is pertinent because it minimizes the pollution by this material and its degradation products. In addition, market demands are met, minimizing the exploitation of new natural resources and reducing the use of fossil fuels. However, lignocellulosic biomass is made up of polysaccharides that are difficult to assimilate, cellulosic fibers, and hemicellulose covered by lignin, the main responsible for the resistance of the material to biodegradation. The anaerobic biodegradation of lignin can be promoted in a sulfate reduction environment with cellulose as a co-substrate. Hydrogen peroxide, a by-product of cellulose biodegradation, acts as a substrate for enzymes to promote lignin degradation. In this study, the applicability of mixing sulfate-rich effluents with lignocellulosic residues for co-treatment and obtaining value-added molecules will be evaluated. Although the system to be studied is constituted by anaerobic routes, a microaerobic atmosphere will be applied to better reproduce the real-scale conditions, since low oxygen concentrations are found in reactors considered anaerobic. Two steps will be used to develop knowledge about the involved metabolic routes and products obtained. A batch for lignocellulosic biomass solubilization, whose effluent will be applied in a second reactor, where the decomposition of metabolic intermediates of anaerobic degradation in biogas will be monitored. The effect of the mode of feeding the substrate, either immediately or distributed over the batch period, will be evaluated. The following lignocellulosic residues will be tested: residue of citrus, sugarcane bagasse, and trub. In addition, a mixture of nitrogen-poor and nitrogen-rich waste, sugarcane bagasse, and trub, respectively, will be studied. The systems will be monitored for the time needed to solubilize lignocellulosic material, molecules obtained, changes in pH, and microbial community. (AU)