A 1,000 m3/d DAF(dissolved air flotation) pilot plant was installed to evaluate the performance of the floating process using the Nakdong River. Efficiency of various DAF operations under different conditions, such as hydraulic loading rate, coagulant concentration was evaluated in the current research. The operation conditions were evaluated, based on the removal or turbidity, TOC(total organic carbon), THMFP(trihalomethane formation potential), Mn(manganese), and Al(aluminum). Also, particle size analysis of treated water by DAF was performed to examine the characteristics of particles existing in the treated water. The turbidity removal was higher than 90%, and it could be operated at 0.5 NTU or less, which is suitable for the drinking water quality standard. Turbidity, TOC, and THMFP resulted in stable water quality when replacing the coagulant from alum to PAC(poly aluminum chloride). A 100% removal of Chl-a was recorded during the summer period of the DAF operations. Mn removal was not as effective as where the removal did not satisfy the water quality standards for the majority of the operation period. Hydraulic loading of 10 m/h, and coagulant concentrations of 40 mg/L was determined to be the optimal operating conditions for turbidity and TOC removal. When the coagulant concentration increases, the Al concentration of the DAF treated water also increases, so coagulant injection control is required according to the raw water quality. Particle size distribution results indicated that particles larger than 25 μm showed higher removal rates than smaller particles. The total particel count in the treated water was 2,214.7 counts/ml under the operation conditions of 10 m/h of hydraulic loading rate and coagulant concentrations of 60 mg/L.

ABSTRACT
1. 서 론
2. 연구방법
    2.1 DAF pilot plant 설치 및 운영
    2.2 시료 샘플링 및 수질분석
    2.3 운영조건별 DAF 운전평가
3. 결과 및 고찰
    3.1 DAF pilot plant 연속운영 수질 결과
    3.2 운영조건별 수질 결과
4. 결 론
References

• 맹민수(아주대학교 환경안전공학과) | Minsoo Maeng (Department of Environmental and Safety Engineering, Ajou University)
• Nirmal Kumar Shahi(단국대학교 토목환경공학과)
• 김동현(단국대학교 토목환경공학과) | Donghyeun Kim (Department of Civil Environmental Engineering, Dankook University)
• 신귀암(아주대학교 환경안전공학과) | Gwyam Shin (Department of Environmental and Safety Engineering, Ajou University)
• 독고석(단국대학교 토목환경공학과) | Seok Dockko (Department of Civil Environmental Engineering, Dankook University) Corresponding author