Nitrogen Removal in the Operation of the Mililani Sewage Treatment Plant.

摘要

The concern over eutrophication of receiving waters has prompted inquiry into practical methods of limiting nutrient inputs,primarily nitrogen and phosphorus,from both point and nonpoint pollution sources. The effluent of the Mililani Sewage Treatment Plant (STP),Oahu,Hawaii,contained only approximately 30% of the total nitrogen that was originally in its raw sewage. During the period that high nitrogen removal rates were observed,raw sewage flowed directly to the Rapid Bloc activated sludge unit. Sludge stabilization was by aerobic digestion. During the fall of 1973, a primary sedimentation tank and an anaerobic digester (which replaced the aerobic digester) were added to the components of the STP. A study was initiated for a one-year period, 1July 1973to 30June 1974,in an attempt to determine the mechanism for nitrogen removal for both before (Phase I) and after (Phase II) modifications to the STP. The major nitrogen loss in the effluent speculated to be by means of gaseous ammonia to the atmosphere,apparently occurred in the aeration unit,settling tank,and aerobic digester.