Pilot-scale coagulation and sedimentation processes were operated to investigate the T-P (Total phosphorus) removal efficiency. A multiple regression model was also derived to predict the water quality improvement effect with river water characteristics. The inflow rates for the pilot-scale facility were 157–576 m3/day, and the coagulant doses were in the range of 13.7–58.5 mg/L (average 38.9 mg/L) for PAC (Poly alum chloride) and 16.5–62.1 mg/L (average 36.0 mg/L) for alum. The results found that the influent BOD (Biochemical oxygen demand) and T-P concentrations were 4.9 mg/L and 0.115 mg/L, and the removal efficiencies were 52.7% and 59.4%, respectively. T-P removal efficiencies on wet weather days were higher by 10% than dry weather days because influent solids influenced T-P's coagulation process. The pH of river water was 6.9–7.8, and the average pH was 7.3. Although the pH variation was not significant, the trend showed that the treatment efficiency of T-P and PO4-P removal increased. Thus, the pH range considered in this study seems to be appropriate for the coagulation process, which is essential for phosphorous removal. The T-P removal efficiencies were 19.6–93.3% (average 59.2%) for PAC and 16.4–98.5%(average 55.9%) for alum; thus, both coagulants showed similar results. Furthermore, the average coagulant doses were similar at 42.4 mg/L for PAC and 41.3 mg/L for alum. When the T-P concentration of the effluent was compared by the [Al]/[P] ratio, the phosphorus concentration of the treated water decreased with an increasing [Al]/[P] ratio, and the lowest T-P concentration range appeared at the [Al]/[P] ratio of 10–30. A seasonal multiple regression analysis equations were derived from the relationships between 10 independent and dependent variables (T-P concentration of effluent). This study could help lake water quality maintenance, reduce eutrophication, and improve direction settings for urban planning, especially plans related to developing waterfront cities.

ABSTRACT
1. 서 론
2. 연구내용 및 방법
    2.1 연구내용
    2.2 재료 및 실험방법
    2.3 운전조건
    2.4 모니터링 방법
    2.5 다중회귀분석
3. 결과 및 고찰
    3.1 하천수 특성별 처리효율 분석
    3.2 파일럿 실험결과를 이용한 수질예측
4. 결 론
References

• 최경수(수원대학교 토목공학과) | Kyoungsoo Choi (Department of Civil Engineering, The University of Suwon)
• 이채영(수원대학교 토목공학과) | Chaeyoung Lee (Department of Civil Engineering, The University of Suwon) Corresponding author