Bioethanol fermentation as alternative valorization route of agricultural digestate according to a biorefinery approach

This study investigates the feasibility of producing bioethanol from solid digestate after a mechanical fractionation (i.e. centrifugal milling), in order to improve the energy recovery from agricultural wastes and the sustainability of anaerobic digestion plants. A bioethanol yield of 37gkg?1 TS was evaluated for the solid digestate fraction. Mass and energetic balances were performed and compared between two scenarios: (A) one-stage bioethanol fermentation and (B) two-stage anaerobic digestion?bioethanol fermentation, in order to evaluate the feasibility and the advantages of the two-stage process. Results revealed that, compared to the one-stage process, the dual anaerobic digestion?bioethanol process permitted: (i) to diversify biofuels production; (ii) to provide the thermal energy sufficient for drying digestate (13,351kWhth day?1), for the subsequent milling step; (iii) to reduce the electric energy requirement for the milling step (from 23,880 to 3580kWhel day?1); (iv) to produce extra electrical energy of 8483kWhel day?1; (v) to improve the reduction of waste streams generated (from 13% to 54% of organic matter removal).

» Author: C. Sambusiti, F. Monlau, A. Barakat

» Reference: Bioresource Technology, Volume 212

» Publication Date: 01/07/2016

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This project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement N° 690103