Determination of optimum conditions for biogas production from cheesewhey using continuous systems

In this study, anaerobic treatability of cheese whey in upflow anaerobic slugde blanket (UASB) reactors and the optimum conditions for biogas production were investigated. Cheese whey taken from the AOÇ cheese producing industries has 70 000mgCOD/L organic load initially. Cheese whey was diluted by the ratios of 1/20, 1/10, 1/5, 1/4, 1/3 and 1/2, respectively. These mixtures were used as the feed solution in the UASB experiments and influence of these parameters was investigated for biogas production. Two parallel UASB reactors of 3,4 liters volume (R1 and R2) were used Reactors were inoculated with the anaerobic activated sludge taken from ASKİ wastewater treatment industry. Throughout the period of the experiments, the reactors were operated at 35ºC by the water recirculation through jackets around the reactors. Cheese whey was fed to the UASB reactors at a rate of 0,56 mL/min with using peristaltic pumps. Both reactors were operated at a hydraulic retention time of 4 days at applied organic loading rates. Recycle with different flow rates was used in R1 for some time. The initial sludge height was 1,8 cm for R1 and 1,6 cm for R2. Granule formation and COD (chemical oxygen demand) reduction with using 1/10 dilution of cheese whey were observed. After 50 day, the height of granular sludge bed was observed 6,5 cm for R1 and 8,0 cm for R2 with COD removal efficiencies of 38,51% and 38,22% for R1 and R2, respectively. Maximum biogas production and COD removal efficiency was obtained with 1/2 dilution of cheese whey used at different COD concentrations. Conseqently, gas production rate was obtained 0,68 cm3/min and 0,29 cm3/min with methane content of 49,79% and 27,93% and granular sludge bed of 20,50 cm and 18,00 cm for R1 and R2, respectively.