Anaerobic biotransformation and methane generation potential of cheese whey in batch and UASB reactors

Anaerobic treatability and methane generation potential of cheese whey were determined in batch reactors. Furthermore, the effect of nutrient and trace metal supplementation on the batch anaerobic treatment, and the high-rate anaerobic treatability of cheese whey in upflow anaerobic sludge blanket (UASB) reactors were investigated. To this purpose biochemical methane potential experiments were conducted and single- and two-stage UASB reactors with granular cultures were operated. In UASB experiments significance of process staging, operational parameters such as hydraulic retention time (HRT), influent chemical oxygen demand (COD) concentration and loading rate were also investigated. The results revealed that nutrient and trace metal supplementation is vital for the anaerobic treatment of cheese whey; the anaerobic methane generation for the cheese whey studied was found to be 424 ml CH4/g COD (23.4 l CH4/l cheese whey); undiluted cheese whey could be treated anaerobically at relatively short HRT values (2.06–4.95 days) without any significant stability problems; HRT values as low as 2–3 days can be used for the anaerobic treatment of cheese whey, with a COD removal efficiency of 95–97% at influent COD concentration of 42 700±141–55 100±283 mg/l.