The whole experiment executed in this study was divided into study of the effect of contact stabilization activated sludge with amendment as one of EBPR applications on the behavior of microorganisms in aerobic and anaerobic zones by measurement of phosphorus concentration in bulk liquid for these zones by taking samples for analyses from each zones in the pilot plant and to observe the uptake and release of total phosphorus by achievement though two batch test, one of these was implemented for a sludge sample (Number 7) from the thickening tank under aerobic condition and another test taking return sludge sample (Number 5) from the final sedimentation tank under anaerobic condition.