Development of a continuous biofilm-based process for the bioconversion of cheese whey into volatile fatty acids

The main goal of the present work was to study the continuous production of volatile fatty acids from a cheese whey powder in anaerobic packed bed biofilm reactors (PPBRs). Vukopor S10 ceramic cubes and granular activated carbon were employed as cell immobilization materials. Experiments were done at 37°C, pH 6. Reactors were frequently sampled for metabolites and biogas analyses. Preliminary batch tests, which were carried out in 100-mL anaerobic Pyrex bottles, demonstrated that the process consisted of two sequential phases: (a) the conversion of lactose into lactic acid and (b) the conversion of lactic acid into a mixture of VFAs. The continuous process was settled up in 1-L glass column and two different hydraulic retention times (9 and 6 days) were applied during the continuous process. Almost 80% of lactose bioconversion was achieved in Vukopor reactors, this corresponding to a 10 g/L VFAs concentration.