Abstract
The change in the time course patterns of nitrite nitrogen content in the anaerobically treated activated sludge was investigated by changing the retention time in aeration tanks and the ratio of BOD to nitrogen content. 1) To treat the synthetic waste water, volumetric load was fixed at 0.54 kg-BOD/m8·day and retention time was changed from 3.7 to 54.5 hr. At any retention time, the activated sludges were in good condition and oxidative decomposition progressed. In this case, all the time course patterns belonged to type A. 2) In the case of BOD : N=100 : 2.9, sedimentation of the sludge became worse and BOD of the effluent increased. The time course patterns belonged to type D. In the case of BOD : N=100 : 11, the activated sludge was in good condition and the oxidative decomposition progressed. In this case, all the time course patterns belonged to type A. In the case of BOD : N=100 : 66, the content of NO2-N, BOD, and COD of the effluent increased and the time course patterns changed from type A and B to type C as the condition of the activated sludge became worse.
