Abstract
By elevating the denitrification capability of activated sludge through the addition of elemental sulfur to the anaerobic denitrification tank of modified aerobic-anaerobic activated sludge process with supplement dephosphothickener, the possibility of simultaneous nitrogen and phosphorus removal without massive internal sludge recycle was investigated using bench scale experimental equipment. Granular elemental sulfur was found to be the best substance as the supplement reduced sulfur source in the anaerobic denitrification tank of modified aerobicanaerobic activated sludge process. 96.6% of influent TOC, 80% of influent T-N and 70% of influent T-P were successfully removed under 20 hours of operational retention time by this treatment method.
Important operational parameters of this simultaneous nitrogen and phosphorus removal process were revealed to be the nitrate loading rate and ORP for the anaerobic denitrification tank. The best treatment result was obtained under the operational condition of 0.028 g NO3-N·g-1 MLSS·d-1 and (Eh) 7 = 200mV for the anaerobic denitrification tank.
