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 (13,351kWhthday(-1)), for the subsequent milling step; (iii) to reduce the electric energy requirement for the milling step (from 23,880 to 3580kWhelday(-1)); (iv) to produce extra electrical energy of 8483kWhelday(-1); (v) to improve the reduction of waste streams generated (from 13% to 54% of organic matter removal).
IATE, CIRAD, INRA, Montpellier SupAgro, Université de Montpellier, 34060 Montpellier, France. Electronic address: cecilia.sambusiti@gmail.com.
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Sambusiti
IATE, CIRAD, INRA, Montpellier SupAgro, Université de Montpellier, 34060 Montpellier, France; APESA, Plateau technique, Cap Ecologia, 64230 Lescar, France.
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Monlau
IATE, CIRAD, INRA, Montpellier SupAgro, Université de Montpellier, 34060 Montpellier, France.
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Barakat
D000383:Agriculture; D000693:Anaerobiosis; D056804:Biofuels; D001709:Biotechnology / Q000379:methods*; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation; D005511:Food Handling / Q000379:methods; D007220:Industrial Waste; D012037:Refuse Disposal / Q000379:methods*
D056804:Biofuels; D007220:Industrial Waste; D000431:Ethanol
Anaerobic digestion; Bioethanol; Digestate; Energy efficiency; Pretreatment