In the traditional air flotation device of dissolved air flotation equipment, the pool depth is generally 2.0 to 2.5 m. This is because the equipment is static, and the water body is moving during operation. When the water body enters the contact area from the reaction chamber, it will produce The change of flow direction and redistribution of flow velocity, that is, to change the water flow into a uniform upward flow, requires a certain amount of time and height to complete this change, and the height is generally not less than 1.5 m.
The water body of the dissolved air flotation equipment is static, and the influence of the disturbance of the water body on the separation of suspended particles and water is eliminated during operation, so that the requirement for its height can be effectively reduced. In addition, in the traditional air flotation device , it is inevitable that mud, sand or flocs will sink to the bottom of the pool. In order to prevent the mud and sand from being brought out of the bottom of the pool, the outlet pipe is generally suspended at a height of 300 mm. Set the overhang section. Through the above analysis, the effective water depth of the shallow air flotation device is generally 400-500 mm.
In the dissolved air flotation equipment, the dissolved air system is equipped with a dissolved air tank, which is calculated according to the actual volume of the dissolved air tank during operation, and its hydraulic retention time is 2 to 4 minutes, while the shallow air flotation device , The gas-dissolving system adopts the gas-dissolving pipe, cancels the filler, makes the volume utilization rate of the gas-dissolving pipe reach 100%, and its hydraulic retention time is only 10-15 s.
Dissolved air flotation equipment In traditional air flotation devices, the scum scraper needs to remove the scum layer regularly, and it cannot be selectively cleaned according to the floating time of the scum during operation, so it not only has a large impact on the water body The disturbance, and the water content of the scum is also relatively large; in the shallow air flotation device, the spiral skimmer is installed at the front of the water distribution system, and the removed scum always floats in the air flotation tank for the longest time (2～ 3 min) scum, that is, the scum with the most complete solid-liquid separation and the smallest water content.
Dissolved air flotation equipment can make the suspended solids adhere to the air bubbles and rise to the water surface, so as to separate the water from the suspended solids, so that the surface active agent in the water can float on the surface of the air bubbles and separate from the water , known as the foam flotation method. The equipment used in the air flotation method includes the air flotation tank for completing the separation process and the auxiliary equipment for generating air bubbles. In water treatment, the air flotation method can be used in occasions where the sedimentation method is not applicable, to separate suspended solids whose specific gravity is close to water and difficult to settle, such as oil, fiber, algae, etc., and can also be used to concentrate activated sludge.
The work of dissolved air flotation equipment mainly relies on the fact that the surface of suspended matter is divided into hydrophilic and hydrophobic. The surface of hydrophobic particles is easy to attach air bubbles, so the air flotation method can be used. Hydrophilic particles can be made hydrophobic by treatment with appropriate chemicals. In the air flotation method in water treatment, coagulants are commonly used to form colloidal particles into flocs. The flocs have a network structure and are easy to trap air bubbles, thereby improving the efficiency of air flotation. Furthermore, if there is a surfactant (such as detergent) in the water, it can form foam and also have the effect of attaching suspended particles to rise together.
