Dissolved air flotation technology has been widely used in water supply, drainage, and wastewater treatment in recent years. It can effectively remove light flocs that are difficult to precipitate in wastewater. Large processing capacity, high efficiency, small footprint, and wide range of applications. Widely used in wastewater treatment for petroleum, chemical, printing and dyeing, papermaking, oil refining, leather, steel, mechanical processing, starch, food and other industries. After the chemical addition reaction, 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 water. 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.

IIIn the field of water treatment, air flotation machines are applied in the following areas:

1. Separate small suspended solids, algae, and other micro aggregates from surface water.

2. Recycling useful substances from industrial wastewater, such as pulp in papermaking wastewater.

3. Replace the separation and concentration of sludge in the secondary sedimentation tank.

This series of air flotation machines is mainly used for solid-liquid or liquid-liquid separation. By using a dissolved gas release system, a large number of fine bubbles are generated in water, which adhere to solid or liquid particles in the wastewater with a density close to that of water, resulting in a state where the overall density is lower than that of water. They rely on buoyancy to rise to the water surface, thus achieving the purpose of solid-liquid or liquid-liquid separation.

3、 Process flow:

4Main Structure Description：

1. The air flotation system of the air flotation machine integrates water inlet, flocculation, separation, water collection, and effluent. Similar to traditional air flotation equipment, it is equipped with a stable flow chamber and a dissolved air release chamber, making the treatment performance more stable and the effect more superior. Stable chamber: The raw water reacted through folded plates has a high flow rate. If it comes into direct contact with dissolved air water, it will dissipate small bubbles, affecting the adhesion of bubbles to flocs and reducing the efficiency of air flotation treatment. If a stable flow chamber is added, the kinetic energy of turbulent raw water will be consumed and enter the dissolved air water release chamber at a uniform speed, effectively ensuring the removal effect. Dissolved air flotation machine dissolved air release chamber: The dissolved air release chamber and the separation chamber are in the same tank. Separated in the middle, the dissolved air water adheres to the flocculated raw water, slowly rises, and enters the air flotation separation chamber, ensuring the contact space and time between the floc and the small bubbles, resulting in a release rate of 80-100% for the dissolved air water.

2. For air flotation equipment, the gas dissolution system is like the "heart" of the air flotation equipment, and is also the main component of the air flotation equipment. At this stage, gas and water are sucked in together at the inlet of the pump, and are sheared and pressurized to mix into dissolved gas and water. The gas-liquid phase is fully mixed and reaches saturation. The gas content of the entire gas dissolution system is as high as 10%, and the gas solubility is 100%, making the distribution of microbubbles during gas dispersion uniform, with an average bubble diameter of less than 30um. This dissolved air system is an improvement and technological innovation of traditional air flotation, which enhances the separation efficiency of air flotation and greatly reduces equipment production and operating costs.

3. The operation mode and speed of the scraper directly affect the water quality of the air flotation effluent and the solid content of the sludge. The vortex concave air flotation system adopts a rotary scraper, which can continuously and uniformly scrape the floating slag into the floating slag tank, reducing the phenomenon of collision between floating slag; In addition, the height adjustable scraper can better adapt to various operating conditions, integrate sewage treatment equipment, and reduce sludge moisture content.

4. The control system adopts advanced electrical components (Delixi or Chint) to ensure the long-term effective operation of the equipment.

5、 Installation, commissioning and precautions

（1） Installation
1. Before installing the equipment, the foundation must be compacted. And use concrete mortar to elevate 100-150mm. It can also be installed overhead, but the foundation must be able to bear the weight of the equipment during operation.
2. After the equipment is in place, it needs to be adjusted horizontally.
3. The equipment needs to be equipped with a cleaning sewer, which can be dug into an open channel or directly connected to a regulating tank through pipelines, in order to discharge the water from the flushing air flotation tank.
4. The connecting pipeline between the sewage inlet and the reaction tank should be as short as possible to prevent the flocs from being damaged in the pipeline.
5. The clear water outlet can be connected to the sewer for discharge. If it needs to enter the next treatment process, it can be directly connected to the next treatment equipment.
6. The sludge outlet can be connected to the sludge tank or sludge treatment equipment.
7. The electrical box should generally be placed on the side of the escalator, and the environment should be clean and tidy.
（2） Debugging:
A、 Before equipment debugging, the following preparations should be made:
1. Clean all the dirt and debris in the pool.
2. Lubricate parts such as water pumps and air compressors with oil.
3. Connect the power, start the water pump, and check if the direction of rotation is consistent with the direction indicated by the arrow. Start the air compressor manually and check if it is running normally. If any abnormal situation is found, promptly investigate the cause.
4. Press the foam scraper switch to move towards one end of the dissolved air system. After running to the end, under the action of the stroke collision block, the scraper moves in the opposite direction until it reaches the sludge tank. The stroke collision block flips up the scraper and presses the stop button to stop scraping.
B、 Trial operation:
1. Add water: Make the water level of the air flotation machine reach about 20-50mm from the upper edge of the sludge tank partition. The water level of the air flotation tank can be adjusted using a water collector.
2. Operation of dissolved gas system: Close all control valves, turn the electrical knob switch to the automatic position, start the water pump, and the air compressor will also enter the automatic working state. Then open the inlet valve, outlet valve, and control valve of the clean water pump in sequence, and the pressure gauge pressure gradually increases, generally reaching 0.4-0.5MPa. At this point, open the outlet control valve of the dissolved air tank to release the dissolved air through the release device into the air flotation tank. A large number of fine bubbles appear in the air flotation tank, causing the clear water to turn milky white. The dissolved air system is normal, and the higher the dissolved air pressure, the higher the density of the released dissolved air bubbles. The gas in the dissolved gas system is provided by an air compressor. Due to the continuous removal of air from the tank by dissolved water, the air inside the tank gradually decreases and the water level rises. When the water level rises to a certain position, the float level gauge will control the operation of the air compressor to ensure sufficient air volume in the tank.
3. Air flotation operation: After the dissolved air system is running normally, the wastewater after the dosing reaction is sent to the air flotation mixing tank. The flow rate is initially reduced and gradually increases to the rated value after it returns to normal.
4. Dissolved water: Dissolved water is first treated with tap water as the reflux water, and then treated with clean water as the reflux water. If the amount of detergent in waste water is large and there are many foam, which will affect the flotation effect, clean water can be used all the time.
5. After the accumulation of floating slag to a certain thickness, start the foam scraper.
6. After the equipment is shut down, the sewage control valve should be closed first, and then the sewage pump should be turned off to scrape off the foam. The foam scraper should be stopped, and then the clean water valve should be opened to allow tap water to run for 30 minutes. The dissolved air outlet and inlet control valve should be closed, and then the clean water pump should be stopped.
（3） Precautions and daily maintenance
1. The pressure gauge reading on the dissolved gas tank shall not exceed 0.6MPa.
2. Clean water pumps, air compressors, and foam blowers should be regularly lubricated with oil. Generally, air compressors should be lubricated every two months and replaced every six months.
3. The air flotation tank should be cleaned regularly depending on the amount of sediment.
4. The sewage entering the air flotation machine must be treated with chemicals, otherwise the effect will not be ideal.
5. Regularly check whether the safety valve on the dissolved gas tank is working reliably.
6. When the release device is blocked, the vacuum valve can be opened to open the release tongue, and it can be cleaned with clean water to flush the blockage. Then, the valve can be closed, which usually only needs to be opened for 10-20 seconds.