The swirl-type sand settling tank features a circular shallow pool design, with larger inlet and outlet openings on the pool walls, and a flat bottom at the bottom of the pool.At the bottom center, there is a larger sand hopper, with mixing and sand discharge equipment installed at the center of the sedimentation pond.
The construction of the swirl sedimentation tank allows the incoming water to enter at a tangent, creating a swirl within the tank. The mechanical mixing blades at the center further enhance the water's swirl. Under the influence of the water vortex and mechanical blades, heavier sand particles fall through the annular orifice near the center into the lower sand hopper, and are then discharged out of the tank via a sand pump or an air lifter.
The vortex sedimentation tank has minimal odor, low organic content in the sediment, and can adapt to water volume changes within a certain range. It is a popular design at present, offering a variety of standardized models for selection.
Primary Design Requirements:
The hydraulic retention time during flow should not be less than30s；
Design hydraulic surface load150~200m3/（m2.h）
Effective water depth should be1.0~2.0mPlease provide the Chinese content to be translated.2.0~2.5；
A stationary pulp leaf separator should be installed in the pond.
One.Operational Management
1Turbulent Sand Sedimentation Tank
The operational focus is primarily on controlling the horizontal flow velocity of wastewater within the pond and its residence time. Larger sand particle sizes in the wastewater allow for an increase in horizontal flow velocity; conversely, it should be decreased. To ensure thorough sedimentation of the sand particles, key control points include: adjusting the overflow weir height first in response to flow changes to alter the effective water depth, followed by considering changing the number of operational pools. The hydraulic retention time affects the sedimentation efficiency; if the retention time is insufficient, the sand particles that should settle will be carried away with the water flow. Conversely, organic matter will settle.
2Aeration Sedimentation Tank
The operational process primarily involves controlling the swirling speed and rotation cycles of wastewater within the pond. The swirling speed is related to the size of the sand particles; the smaller the particle size, the higher the required swirling speed. However, the swirling speed should not be too high, as it may cause settled sand particles to resurface. The swirling speed is influenced by factors such as the geometric dimensions of the sand settling pond, the installation position of the diffuser, and the aeration intensity. The number of rotation cycles is related to the sand removal efficiency; the more rotation cycles, the higher the sand removal efficiency. To remove particles with a diameter of0.2mmThe grains of sand, requiring maintenance.0.3m/sThe rotation speed of the pool is at least three rotations. During operation, the aeration intensity can be adjusted to change the vortex speed and the number of rotations, ensuring a stable sand removal efficiency. When the wastewater volume entering the sedimentation pond increases, the horizontal flow speed will also accelerate; at this point, the aeration intensity should be increased.
3Timely sand and slag removal
The amount of sediment depends on the water quality of the incoming water. During operation, it is crucial to carefully observe and summarize the changes in sediment quantity and promptly remove it. Excessive intervals between sediment removal can block the sediment discharge pipes, sand pumps, and jam the sand scraper machinery; conversely, too short intervals may increase the sediment discharge volume and water content, making subsequent treatment more difficult. The floating debris on the sedimentation tank should also be cleared regularly.
