Title: Practical planning of oxidation ditch process using axial flow pump for aeration
Abstract: An oxidation ditch process uses falling water as aerator with the falling water being caused by a pump. Submergible motor pump (D300mm, 7.5kWh) was used in the previous experiments and it was changed to axial flow pump (D500mm, 3.7kWh) this time. Several points regarding the pump change and introducing this oxidation ditch process into a practical use are considered in the present paper. The rotation speed of the axial flow pump (250 rpm) was lower than that of the submergible motor pump (1,600 rpm). Floc diameter using the axial pump was found to be larger than that of the submergible motor pump. It is found that these differences had no serious effects on the experimental results carried out after 1994. However, larger floc diameter is ascribed to the mixed liquor entering into sedimentation tank drawn from the water surface of the ditch. If the mixed liquor is drawn at a point near the bottom, the treatment results will be the same as the experimental results before 1994 and the scum will not enter sedimentation tank. The results revealed that a baffle and a shower are necessary to prevent scum formation on the water surface of the ditch. Small air bubbles attached on the flocs of sludge, since air and water mixed strongly with the pump and the falling water. Other parameters such as length of the ditch, suitable interval of intermittent aeration, control of scum formation, and the nitrogen and phosphorus removal are also investigated.
Publication Year: 1998
Publication Date: 1998-01-01
Language: en
Type: article
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