Journal of Korean Society of Water and Wastewater (상하수도학회지)

The Korean Society of Water and Wastewater (대한상하수도학회)
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Design and application of a high-rate dissolved air floatation process in a drinking water treatment plant: A field study for turbidity and algae removal

정수처리장 고속 용존공기부상공정의 설계 및 적용: 탁도 및 조류 제거를 위한 현장연구

  • Hyun Je Oh (School of Civil and Environmental Engineering, University of Science and Technology)
  • 오현제 (과학기술연합대학원대학교 건설환경공학과)
  • Received : 2022.11.14
  • Accepted : 2022.12.09
  • Published : 2022.12.15
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Abstract

A high-rate dissolved air flotation (DAF) process, with a surface loading rate of 20-40 m3/m2/h, was introduced at the Y-Drinking Water Treatment Plant in South Korea. First, the DAF and granular activated carbon (GAC) processes were combined in the reactor, and the pilot plant was operated at 500 m3/day. The results from these tests demonstrated that there were significant decreases in turbidity, algae, geosmin, and 2-methylisoborneol (2-MIB) following implementation of the two processes. Then, the optimum design factors were used and the DAF system was introduced at the field-scaled plant (5,000 m3/day). The removal rate of algae and turbidity was evaluated over 56 days in summer. The number of algae in the treated water was maintained at below 20-30 cells/mL, which represented an algae removal efficiency of 80-89%. The effluent turbidity was compared to the conventional sedimentation and DAF processes, and the average turbidity removal efficiency was 77%. These findings indicate that the high-rate DAF process is a promising method for the removal of low-density solids such as turbidity and algae during the treatment of drinking water, especially in summer. Additionally, GAC represents an acceptable treatment option to remove taste-and-odor-causing compounds (e.g., geosmin and 2-MIB).

국내 Y정수처리시설에 20-40 m3/m2/h의 표면부하율을 갖는 고속 용존공기부상공정을 도입하였다. 우선, 용존공기부상공정과 입상활성탄 공정이 결합된 반응기를 일처리용량 500 m3/day의 조건으로 운전하였다. 운전결과는 두 공정이 원수내 탁도, 조류, 지오스민, 2-MIB를 감소시킬 수 있음을 증명하였다. 도출된 최적 설계요소를 활용하여 현장규모의 공정(5,000 m3/day)에 용존공기부상공정을 도입하였다. 여름철 56일간 조류와 탁도 제거율을 평가하였다. 처리수 내 조류의 개체수는 20-30 cells/mL 이하로 유지되었으며, 조류 제거효율은 80-89%를 기록하였다. 침전법 및 용존공기부상공정 처리수질의 탁도 제거효율을 비교한 결과 평균 탁도 제거효율은 77%를 나타냈다. 이러한 결과들은 고속 용존공기부상공정이 여름철 음용수의 탁도 및 조류와 같은 저밀도 고형물을 제거하는데 유의미한 방법임을 나타냈으며, GAC는 맛·냄새를 유발하는 화합물(지오스민, 2-MIB)를 제거할 수 있는 공정 옵션인 것을 확인하였다.

Keywords

Acknowledgement

This work was supported by Korea Environment Industry & Technology Institute (KEITI) through Project for developing innovative drinking water and wastewater technologies Program, funded by Korea Ministry of Environment (MOE) (2020002700003).

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