Integration of anaerobic digestion and chain elongation technologies for biogas and carboxylic acids production from cheese whey

Cheese whey (CW) used for the production of various chemicals in different studies, but no studies designed to produce multiple energy in the form of short-chain/medium-chain carboxylic acids, and biohydrogen (H-2) using bio-augmentation strategy by integrating the anaerobic digestion and chain elongation technologies. To achieve this, CW and mixed anaerobic bacteria were kept in an anaerobic chamber for 14 d to produce short chain carboxylic acids (SCCA, acetic (C2), propionic (C3), and butyric (C4) acids), and these SCCA were again converted to medium chain carboxylic acids (MCCA) like hexanoic (C6), heptanoic (C7), and octanoic (C8) acids using enriched bacterial culture, which was bio-augmented with Clostridium kluyveri. SCCA, MCCA, and biogas were analyzed with HPLC and GC. Higher amounts of SCCA, i.e., C2 (10 g/L), C4 (8.1 g/L), and MCCA, i.e., C6 (4.8 g/L), were produced. Biohydrogen (H-2) existed in the highest proposition (69%) in biogas composition. Results meant that bio-augmentation strategy could be used for the conversion of CW into valuable carboxylic acids and H-2, which have high potential in today's market.