Electrofermentation of food waste – Regulating acidogenesis towards enhanced volatile fatty acids production

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2018-02, Vol.334, p.1709-1718
• Main Authors: Shanthi Sravan, J., Butti, Sai Kishore, Sarkar, Omprakash, Vamshi Krishna, K., Venkata Mohan, S.
• Format: Article
• Language: English
• Subjects: Biohydrogen; Biohythane; Chain elongation; Electrofuels; Fermentation; Metagenomics
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2017.11.005

[Display omitted] •Electrofermentation of food waste towards enhanced fatty acid production.•External stimulation regulates acidogenic fermentation process.•Electrofermentation influenced electron kinetics toward enhanced product recovery.•Kapp showed distinct disparity in bacterial electrometabolism. Electrofermentation (EF) was used to overcome the thermodynamic limitations of conventional microbial fermentation and regulate the metabolism towards specific biobased products synthesis. Three single chambered EF systems (Applied potential (AP: −0.6 V), Closed circuit (CC: 100 Ω), Control (C)) were individually operated using composite canteen based food waste (FW) (COD-10 g/l) to comparatively analyze the effect of electrical stimulation on enhancing rate of fermentation. The total volatile fatty acids (VFA) showed higher production in AP (4595 mg/l) when compared to CC (3593 mg/l) and C (2666 mg/l). Fatty acid profiles (C2–C4) with individual compositions showed higher amount of acetic acid (C2: HAc) followed by butyric acid (C4: HBu) and propionic acid (C3: HPr). AP showed higher amount of C2: HAc (3221 mg/l) followed by C4: HBu (900 mg/l) and C3: HPr (474 mg/l), while CC showed higher C2: HAc (2332 mg/l) followed by C4: HBu (1233 mg/l) and C3: HPr (388 mg/l) when compared to C which showed higher C2: HAc (1422 mg/l) followed by C4-HBu (655 mg/l) and C3-HPr (589 mg/l). Co-generation of biogas was higher in AP [bioH2 (26%) and bioCH4 (4%)] followed by CC [bioH2 (22%) and bioCH4 (1.3%)] and C [bioH2 (11%) and bioCH4 (6%)]. Fermentation induced with electron flux mechanism depicted the ability to elongate the chain length. Electrochemical characterization showed distinct disparity in electron transfer rates (Kapp) along with waste remediation. The inferences concluded the key role of electrical stimulation on fermentation to enhance the conversion of conventional substrates to targeted carboxylic acids. Biohythane, an alternate renewable biofuel was also produced when bioH2 and bioCH4 are mixed in appropriate ratios. EF is an emerging technology that could open new frontiers in waste biorefinery by integrating bioprocesses for platform chemicals production through sustainable microbial electrochemical technologies.