dissolved air flotation machine
Air flotation
Air flotation is a shortened form of air flotation machine, also known as air flotation method in water treatment. It forms highly dispersed small bubbles in water, adheres to solid or liquid particles with hydrophobic groups in wastewater, and forms a three-phase mixture system of water gas particles. After the particles adhere to the bubbles, they form flocs with an apparent density less than water and float up to the water surface, forming a scum layer that is scraped off, thereby achieving solid-liquid or liquid-liquid separation.
Air flotation is the production of a large number of fine bubbles in water, which adhere to small suspended particles in wastewater. The "bubble particle" complex with the overall density less than water is formed, and the suspended particles rise to the water surface together with the bubbles, forming foam scum, so that the suspended solids in the water can be separated. Air flotation is an alternative method to sedimentation
The Principle and Function of Air Floatation Machine
Principle: The principle of an air flotation machine is that the dissolved air system generates a large number of micro bubbles in water, causing air to adhere to suspended particles in the form of highly dispersed micro bubbles, resulting in a density less than water. It is a water treatment equipment that uses the principle of buoyancy to float on the water surface and achieve solid-liquid separation.
Function: Air flotation machine is a device for removing solid suspended solids, grease, and various colloidal substances from various industrial and municipal wastewater. This equipment is widely used for the treatment of industrial wastewater and municipal wastewater in oil refining, chemical engineering, brewing, vegetable oil production and refining, slaughtering, electroplating, printing and dyeing, etc.
Application of Air Floatation Machine
In water treatment technology, air flotation is not suitable for the treatment of high turbidity raw water. Generally speaking, air flotation equipment is mainly used in the following situations:
1. In the process of drinking water treatment, it is used to treat low turbidity, algae, and some plankton (usually the annual suspended solids content in raw water is below 100mg/L).
2. Oil water separation is used for oily (including emulsified oil) wastewater in petroleum, chemical, and mechanical manufacturing industries.
3. Physicochemical treatment of organic and inorganic wastewater.
4. Useful materials used for recycling wastewater, such as pulp fibers and fillers from paper mill wastewater.
5. Raw water with high water pollution, high chromaticity, and low dissolved oxygen.
6. Used for the concentration treatment process of surplus sludge in sewage treatment plants.
The air flotation equipment used in the water treatment process can be divided into cloth air flotation equipment, dissolved air flotation equipment, and electrolytic air flotation equipment. Pressurized dissolved air flotation is often used in production.
Classification of air flotation processes
Various forms of air flotation water purification technology have been developed. According to the ways in which bubbles are generated, they can be divided into: air distribution flotation (including rotor crushing method, microporous air distribution method, impeller dispersed air flotation method, etc.); Dissolved air flotation (including true air flotation, full dissolved air flotation, partial dissolved air flotation, and partial reflux dissolved air flotation); Electrolytic air flotation method; Biochemical gas flotation (including biological gas production flotation and chemical gas production flotation).
Composition of pressurized dissolved air flotation equipment
The pressurized dissolved air flotation equipment mainly consists of three parts: air saturation equipment, air release equipment, and mixing equipment with raw water, as well as solid-liquid or liquid-liquid separation equipment.
Method for generating bubbles in air flotation process
1. Disperse air to produce bubbles
The core of microporous gas distribution method is the manufacturing of microporous plates.
The produced microporous plate is mechanically cut into small bubbles when gas passes through the micropores on the plate from bottom to top through physical processes. The resulting bubbles are then used for air flotation to remove pollutants from water.
2. Disperse air to produce bubbles
Impeller cutting method:
The suction process of the impeller cutting method uses the high-speed rotation of the impeller to form negative pressure under a fixed cover plate. Air is sucked in from the air pipe, and the air entering the water is fully mixed with the circulating water flow. The high-speed rotation of the impeller disperses into small bubbles and throws them out of the guide blade. After passing through the stable flow baffle for energy dissipation, the bubbles rise vertically.
Due to the large size of bubbles generated and the severe turbulence of water flow caused by impeller rotation, the treatment effect of impeller cutting method is not ideal.
3. Disperse air to produce bubbles
Jet method:
Through the jet device, water is ejected at high speed from the nozzle while also carrying a certain amount of surrounding air, forming a vacuum zone at the nozzle mouth, allowing air to be continuously sucked in and enter the throat of the jet device with the water flow. In the throat, air is cut into small bubbles in a turbulent state, achieving the effect of air flotation.
