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 an...