A CASE STUDY ON THE PARALLEL PRODUCTION OF BIOMETHANE AND FOOD GRADE CO2 FROM BIOGAS

Abstract: This work presents a case study, aimed at biogas upgrading with simultaneous purification of methane and CO2. The study was performed on industrial plant of biogas production constructed by Tecno Project Industriale Srl. It has a biomass treatment capacity of 400.000 ton/year and can treat 6250 m3/h of biogas1. The objective was to evaluate the feasibility of biogas upgrading to distribution grid quality biomethane via different steps, including CO2/CH4 separation by polymer membranes. Fig. 1. Three-stage of membrane modules for CO2/CH4 separation connected to CO2 recovery unit. The innovative aspect is the final purification of CO2 from useless by-product to a food-grade quality gas for the food and beverage industry. The chemical purity of different process streams was analysed by a certified laboratory and was compared with the guidelines of the European Industrial Gases Association and the International Society of Beverage Technologists (EIGA /ISBT)2. With a purity of 96.3 vol%, methane respects the purity requirement for the household network. With a purity of 99.9 vol% the CO2 proves to be chemically and microbiologically suitable for food-grade applications, closing the CO2 loop of Biogas production. References 1 E. Esposito et al., World Acad. Sci. Eng. Technol. Int. Sci. Index, Chem. Mol. Eng., 2017, 4, 2153. 2 European Industrial Gases Association, 2008, 13.