Digestion of cheese whey with anaerobic rotating biological contact reactors

Abstract A laboratory-scale anaerobic rotating biological contact reactor receiving full strength cheese whey was studied over a range of hydraulic retention times from 11 to 5 days at 35°C. Methane production rates ranging from 1·68 to 3·26 litres CH 4 litre −1 and a 76 to 93% reduction in chemical oxygen demand were achieved. At hydraulic retention times shorter than 5 days, steady-state operation could not be maintained for reactors receiving either full strength or diluted whey. A two-stage fermentation system was also studied; the results indicated that stable operation and treatment efficiency (89·5% COD removal) could be achieved.