comparative study on start – up performance of huasb and af reactors treating poultry slaughterhouse wastewater

a study was performed in hybrid up flow anaerobic sludge blanket (huasb) and anaerobic filter (af) reactors to compare the start-up time and optimum hrt required for the treatment of poultry slaughterhouse wastewater under similar loading conditions. initially, the reactors were started at an olr of 0.77 kg cod/m3.d and hrt of 36 h. loading rates were increased by reducing hrt 24, 16, 12, 10 and 8h which corresponds the olr of 1.15, 1.74, 2.27, 2.74, 3.43 kg cod/ m3.d. huasb reactor showed tcod and scod removal efficiencies of 80% and 86%, respectively at an optimum hrt of 10 h whereas af reactor showed 70% (tcod) and 79% (scod) at optimum hrt of 12 h. reducing hrt beyond 10h in huasb reactor shown sludge wash out and lower cod removal efficiencies of less than 80% and beyond 12 h in af marked decreased efficiencies as low as 66%. huasb and af reactors took 120, 147 respectively, for complete start-up. the granules of 2-2.5 mm sizes were observed in huasb and less than 1 mm were observed in af with settling velocities ranging between 0.5-0.83 m/min and 0.5-0.65m/min, respectively. from residence time distribution studies, dispersion numbers (