New generation biofuel from whey: Successive acidogenesis and alcoholic fermentation using immobilized cultures on ?-alumina

• Published in: Energy conversion and management 2017-03, Vol.135, p.256
• Main Authors: Boura, Konstantina, Kandylis, Panagiotis, Bekatorou, Argyro, Kolliopoulos, Dionysios, Vasileiou, Dimitrios, Panas, Panayiotis, Kanellaki, Maria, Koutinas, Athanasios A
• Format: Article
• Language: English
• Subjects: Acid production; Aluminum oxide; Biodiesel fuels; Biofuels; Biomass; Bioreactors; Biorefineries; Cheese; Cheese industry; Dairy products; Esterification; Ethanol; Exploitation; Fermentation; Fuels; Kefir; Lactic acid; Lactose; Organic acids; Substrates; Sugar; Whey
• ISSN: 0196-8904; 1879-2227
• DOI: 10.1016/j.enconman.2016.12.050

Cheese whey exploitation in a biorefinery manner is proposed involving anaerobic acidogenesis by a UASB mixed anaerobic culture and alcoholic fermentation by kefir. Both cultures were immobilized on y-alumina. The produced organic acids (OAs) and ethanol could be esterified to obtain a novel ester- based biofuel similar to biodiesel. During acidogenesis, lactic acid-type fermentation occurred leading to 12 g L-1 total OAs and 0.2 g L-1 ethanol. The fermented substrate was subsequently supplied to a second bioreactor with immobilized kefir, which increased the OAs content (15 g L-1), especially lactic acid, and slightly the ethanol concentration (0.3-0.4 g L-1). To further increase ethanol concentration, a second experiment was conducted supplying whey firstly to the immobilized kefir bioreactor and then pumping the effluent into the acidogenesis bioreactor, resulting in 40% increase of OAs and 10-fold higher ethanol content. The residual sugar was ~5O% of the initial whey lactose; consequently, future research could result to further increase of ethanol and GM.