Anaerobic Degradation of Molasses Stillage in a Pilot UASB Reactor

The feasibility of a mesophilic anaerobic treatment of an alcohol distillery wastewater (beetmolasses stillage) was studied in a 1300 i upflow anaerobic sludge blanket (uasb) reactor fora period of 180 days. the system was seeded with 600 l of mesophilic anaerobic sludge harvestedfrom the bottom of a dairy anaerobic lagoon. nutrients were added to acidified effluent and afteradjusting the ph in an equalization tank, the system was fed with a diluted effluent containingcod in the range of 1000-11000 mgjl at 30°c. initially, the system had an olr of 1 kg codm-3 d-1 and upflow velocity was maintained at 0.6 m/h (hrt=: 6 h) throughout the study. agradual increase in olr, through increased feed concentration, resulted in an excessive sludgewashout necessitating the addition of calcium carbonate to act as a nuclei for granule formation.after 20 days of operation and at an olr of 5.3 kg cod m-3 d-1 , signs of granule formationwere observed, as indicated by increased vss at the bottom of the reactor and reduced effluentvss. at this point, the loading to the system was increased in four stages up to 16 kg codm-3 d-1 (cod removal efficiency of 95%) to evaluate the optimum operational conditions ofthe system. during this period, the vss/ss ratio remained constant at 0.83 and the slr variedfrom 0.14 to 0.81 kg cod kg-1 vss d-1 . the performance of the system, based on unit reactorvolume and unit microbial mass, was 10 kg scad m-3 d-1 and 0.25 kg scad kg- 1 vss d-1 ,respectively.