Though SBR as biological phosphorus removal process have a lot of advantages such as excellent organic and phosphorus removal, low excess sludge production, and prevention of bulking, it has not been used widely in real fields owing to lack of stabiltity and reasonable operating parameters. The objective of this study were to develope new operating parameters for the enhancement of BPRP. A liter air-lift type reactors were used to study HRT, COD/P ratio effect, Organic loading effect, Population dynamics. Temperature was maintained at $20\,^\circ\!C$ during the operation. Turbine mixing type reactor of 3.5L was used in application to sewage and VFA effect test. The effluent of sludge digester was applied as volatile fatty acid(VFA) source. Population dynamics analysis was comprised of the study of bacteria frequency according to their diameter, total enumeration with viable count, qualitative and quantitative study of poly-p with volutin stain and the acid digestion method respectively. The results of this study were as follow : 1. Minimum anaerobic reaction time required for maximum phosphorus release is 1 hr and for exellent organic(COD) removal 0.5 hr. At least, two hours is required for aerobic reaction to ensure sufficient phosphorus uptake from liquid to microbial cells. About 94.5\% of COD was removed during anaerobic reaction. 2. COD/P ratio of influent has considerable relationship with phosphorus removal, whereas it did not affect COD removal. As the COD/P ratio was increased to over 20, the phosphorus removal was sustained consistantly about 98\% irrespective of sewage and synthetic wastewater. But, linear relationship existed in the range of COD/P ratio less than 20, as shown below. phosphorus removal(\%) = 1.31[COD/P ratio] - 145 ( for sewage ) phosphorus removal(\%) = 6.2[COD/P ratio] - 13 ( for synthetic waste ) 3. Up to COD loading of 1000 mg/1, the phosphorus and COD were removed properly. As the organic loading was increased to 2000 mg/1, 4000 mg/1 and 10000 mg/1, phosphorus removal became unstable and COD removal was decreased sharply with drop of pH to 4.0-4.5. 4. The analysis of coulter multisizer showed that most bacteria in the activated sludge were around 0.446$\mu$m in diameter and those in the phosphorus removal process were around 0.9$\mu$m. This indicated that there was a substantial difference in the species of dominant bacteria between phosphorus removal process and activated sludge process. The volutin stain gave a distinct contrast between poly P containing bacteria and the others in BPRP sludge.
