1. The dissolved air pressure in the air flotation tank of the air flotation equipment is 0.2~0.4MPa, and the reflux ratio is 25%~50%. In order to obtain a sufficient copolymerization effect, it is generally necessary to add flocculants, and sometimes additives. The mixing time after dosing is usually 2-3 minutes, and the reaction time is 5-10 minutes.
2. Air flotation equipment The air flotation pool generally adopts a rectangular reinforced concrete structure, which is often built together with the reaction pool. The top of the pool is equipped with a light cover plate, and a slag scraper is installed inside. The horizontal flow rate of the water in the pool is 4~5m/s, which should not exceed 10/ s. The aspect ratio of the air flotation pool is usually not less than 4. The width of the small and medium-sized air flotation pool can be 4.5m, 3m or 2m. The width of the large air flotation pool can be determined according to the specific situation. Generally, the width of a single cell does not exceed 10m, and the length of the pool does not exceed 15m. .
3. In order to prevent flocs from being broken, the connection of water flow should be stable. Therefore, the air flotation tank and the reverse vertical tank should be built together as much as possible, and the water velocity entering the contact chamber of the air flotation tank should be lower than 0.1m/s.
4. The height of the contact chamber of the air flotation tank of the air flotation equipment is preferably 1.5~2.0m, and the plane size should meet the requirements for the arrangement of the dissolved air releaser. Among them, the rising velocity of the water flow should be controlled at 10~20mm/s, and the residence time of the water flow in it should be greater than 60s.
5. The depth of the separation chamber is generally 1.5~2.5m, and the superelevation is not less than 0.4m. Among them, the downward flow velocity range of the water flow should be between 1.5~3.0mm/s, that is, the surface load should be controlled between 5.5~10.8m3/(m2 h), and the residence time of the wastewater in the air flotation tank should not exceed 1.0h , generally 30~40min.
6. The water collection of the air flotation tank of the air flotation equipment should ensure the balance of the water in and out, so as to keep the water level of the air flotation tank normal. Generally, the water collecting pipe is connected with the outlet well, and the flow velocity of the water collecting pipe should be controlled at about 0.5m/s. Small and medium-sized air flotation tanks are equipped with water level regulating pipe valves on the upper part of the outlet well; large-scale air flotation tanks must be equipped with controllable overflow weirs to adjust the water level and flow.
