Dissolved air flotation machine, also known as pressurized dissolved air flotation, uses air pressure to dissolve more air in water, and then releases a large number of micrometer sized small bubbles in the water through pressure non aggregation. During the process of small bubbles floating up, it will adsorb suspended solids and flocculent substances in the sewage and float up together. Dissolved air flotation machine achieves the effect of clean water quality through this principle.
After the addition of chemicals, the sewage enters the mixing zone of air flotation and comes into contact with the released dissolved air water, causing the flocs to adhere to fine bubbles before entering the air flotation zone. Under the action of buoyancy, flocs float towards the water surface to form floating scum. The clear water in the lower layer flows through the collector to the clear water tank, and a part of it is refluxed for use as dissolved air. The remaining clear water flows out through the overflow port. After the floating slag on the surface of the air flotation tank accumulates to a certain thickness, it is scraped into the sludge tank of the air flotation machine by a scraper and discharged.
According to different design requirements, dissolved air flotation machines can be divided into three types: horizontal flow, vertical flow, and Nicolney pump. The working principle of the dissolved air flotation machine discussed in this article is the working principle of the laminar dissolved air flotation machine, which is also a widely used dissolved air flotation machine.
The integrated air flotation equipment is divided into four parts: (1) dosing coagulation part, (2) reflux water-soluble gas release part, (3) air flotation part, and (4) electrical control part.
（1） Medication coagulation section:
Wastewater is pumped from the sewage tank to the vortex reactor by a sewage pump. Generally, it is recommended to add medication before the sewage pump. This can allow the liquid medicine and sewage to be thoroughly mixed by rotating the impeller of the sewage pump. The medicine is supplied by a dosing device. The treated wastewater enters the vortex reactor and undergoes sufficient coagulation.
（2） Reflux water-soluble gas release part:
The effectiveness of air flotation mainly depends on the effect of dissolved air in the reflux water and its release. This air flotation adopts high-efficiency and energy-saving dissolved air and release equipment. Mix and dissolve the compressed air from the air compressor with the treated return water pressurized by the water pump in the dissolved air tank to form dissolved water. The working pressure of the gas tank is generally 2-3.5kg/cm2.
（3） Air flotation section:
The sewage treated with chemical coagulation enters the air flotation tank, and the dissolved air in the dissolved air tank is suddenly depressurized by the dissolved air release device at the lower part of the inlet and outlet of the water pipe, causing a large number of microbubbles to be released from the air dissolved in the water. During the rising process, microbubbles encounter suspended solids that have already condensed in the sewage. The microbubbles attach to the suspended solids, causing them to quickly float up, so that the suspended solids treated in the sewage float on top. Then they are scraped off and discharged into the sludge tank through the scraper at the upper part of the air flotation, while the bottom of the tank is discharged through treated clean water.
（4） Electrical control part:
This equipment is equipped with an electrical control cabinet, which can achieve unmanned operation after debugging and installation. The electric control cabinet controls the operation of equipment such as gas water pumps, foam scrapers, and dosing mixers.