포기조에서 산기관의 설치위치가 용존산소에 미치는 영향 연구

Abstract

Currently, countries worldwide are trying to reduce greenhouse gases, and Korea also attempts to decrease industrial greenhouse gas emissions. Aeration is the most energy-demanding process in a sewage treatment facility. Improvements in the aeration process''s efficiency will significantly contribute to national goals and climate change response. We conduct the aeration performance test to derive the optimum conditions for the diffuser arrangement and its installation depth in the aeration tank. The ball-type diffusers are installed at about 1/3 level (900 mm below the water surface) and 2/3 level (1,800 mm below the water level) of the water tank. We observed the change in aeration tank dissolved oxygen (DO) concentration with the blown air volume and time. The average increase in DO concentration ranged from 1.13 mg/L to 1.73 mg/L when aeration was conducted at the middle of the aeration tank. In contrast, the average increase in DO concentration ranged from 0.52 mg/L to 1.04 mg/L when aeration devices were installed at the bottom of the aeration tank. These results indicated that installing diffusers in the middle depth of the aeration tank was more effective for oxygen delivery and power requirement. The average air power required to drive the DO between 0.5 mg/L and 3.0 mg/L for an hour is found as 0.42 kWh and 0.38 kWh for the bottom and middle part of the tank, respectively. The results show 9.5% energy saving for aeration in the middle. The results reveal that the lower the depth of the aeration diffuser installation, the better the oxygen delivery. Therefore, it will be possible to construct an aeration system with better energy efficiency when aeration diffusers are installed at low-water-depths.