CO_2 CAPTURE AND CONVERSION IN ANAEROBIC DIGESTION OF ORGANIC WASTES FOR ENHANCED METHANE PRODUCTION: DEMONSTRATION PROJECT IN BOLOGNA WWTP

摘要

The development of innovative technologies is desirable to accomplish the greenhouse gas reduction targets. The present work is aimed at combining CO_2 capture and its use in conjunction with biomass conversion. In constant association with lab-scale and pilot trials, the project focused on demonstration activities directly on the operative sites of industrial partners. CO_2 was captured from the local sludge incinerator flue gas and recovered as a concentrated stream. A Two-Phase Anaerobic Digestion (TPAD) process was successfully established and maintained, leading to specific microbial adaptation and selection and to a sharp phase separation. By enhancing the hydrolytic and fermentative steps, CO_2 injection leads to efficient biomass degradation and VFA accumulation. CO_2 intake in the acid phase has a positive impact on the overall GHG balance. The integrated approach of CO_2 capture from combustion gas and its use in anaerobic digestion of sludge has improved the economic and environmental features of biomethane production.