As shown in Fig. 9 in the batch test under anaerobic condition by using a sludge sample (Number 5) from the final sedimentation tank without any external additions of acetate source at duration time 60 min the TP concentration in bulk liquid was above 0.20 mg/l at the start of the test, and then the TP value takes to increase gradually to become 0.88 mg/l. at the middle of the batch test duration, and to become more than 1.3 mg/l at the end of test.