Enhanced production of volatile fatty acids (VFAs) from sewage sludge by β-cyclodextrin

Organic matter in sewage sludge can be converted into volatile fatty acids (VFAs) as renewable carbon sources. This work for the first time demonstrates that β-cyclodextrin (β-CD) molecules enhance sludge hydrolysis for production of VFAs. With 0.2 g β-CD g−1 dried solids (DSs), the increment rate for VFAs peaked at 4200 g g−1 DSs g−1 β-CD, with acetate and propionate as the predominant VFAs. Compositional and microbial community analyses confirm that the β-CD molecules break a cell’s membrane, such that it releases intracellular substances. Although β-CD molecules inhibited activities of methanogens, they did not impair those of acid-forming bacteria, thereby demonstrating that β-CD-assisted VFAs are renewable organic carbon sources, except in anaerobic digestion processes.