Abstract
A draft-tube-type reactor was applied to a nitrification-denitrification process. The data obtained through the continuous treatment of domestic sewage demonstrated that 97% of BUD, 88% of ammonia nitrogen, and 84% of total nitrogen in influent could be removed under the condition that HRT was kept around 10.4h Appropriate values of design parameters (the ratio of draft tube diameter to reactor diameter and effective height of the reactor) and operational parameters (BOD-SS loading rate, aerobic zone ratio, anoxic zone ratio and C/N ratio) were also clarified. In addition, sludge produced through the treatment was from 28% to 56% less than that produced throughthe treatment by conventional activated sludge processes.
