Author: Site Editor Publish Time: 2023-12-08 Origin: Site
Dissolved Air Flotation (DAF) is a physical and chemical solid-liquid separation technology commonly used in water treatment. Dissolved air flotation working principle is based on the adhesion and buoyancy of tiny bubbles and is used to remove suspended matter, grease or other solid particles from separated from the water. How does dissolved air flotation work? The following is the basic working principle of dissolved air flotation:
One of the key steps in dissolved air flotation system is the generation of bubbles. Bubbles are tiny bubbles formed by dissolving compressed air into water through an air pump, and then quickly releasing the gas. When the bubble falling speed is small, pollutants suspended in the water are adsorbed on the bubbles, so that the bubbles and pollutants are together. Float on the water to achieve the purpose of separation.
a.Pressure release bubble generator:
This is one of the most common methods of generating bubbles. In this method, water is saturated with gas (usually air) under high pressure, and then by releasing the pressure, the gas in the water forms a large number of tiny bubbles. The pressure release bubble generator includes the following key parts:
·Saturated dissolved device: Here the water comes into contact with high-pressure air, causing the air to dissolve in the water.
·Relief device: High-pressure saturated water passes through a release device, usually a pressure-reducing valve, and the pressure is suddenly and momentarily released, causing the gas in the water to form tiny bubbles.
b. Gas-liquid mixed bubble generator:
In this method, gas and water mix to form bubbles. The advantage of this method is that the size and distribution of the bubbles can be controlled by adjusting the ratio of gas to water. The gas-liquid mixed bubble generator includes the following key parts:
·Gas introduction port: Introduces gas into the water flow.
·Mixing chamber: In the mixing chamber, gas and water are mixed to form bubbles.
·Bubble generation port: Inject the mixed bubbles into the water to be treated.
No matter which method is used, the size and distribution of bubbles are very important to the effect of air flotation machine. Smaller bubbles generally provide greater surface area, increasing the chance of suspended solids or grease particles attaching, thereby increasing separation efficiency. Therefore, during the bubble generation process, engineers often adjust the size and distribution of bubbles based on specific application needs and water quality characteristics.
The released tiny bubbles float up in the water and attach to the surface of suspended solids, grease or other solid particles when they come into contact with them. During this process, the surface tension of the bubbles causes them to bind to the suspended particles.
Suspended matter or grease particles attached to the surface of the bubble form an airbag-like structure, which is lighter than water, so they float with the bubble.
During the process of floating, the bubbles continue to combine with the surrounding suspended particles to form air bags, which increases the effective radius of the particles, thereby enhancing the buoyancy of the particles.
When the bubble-particle complexes float to the surface of the dissolved air flotation tank, they form a foam layer. The foam layer contains impurities such as suspended solids or grease. This foam layer is pushed to the center of the water surface by the scraper, forming concentrated foam. Below the foam layer is relatively clear water.
On the surface of the pool, there is usually a foam scraping device to remove floating foam. These foams contain suspended solids or grease, which are scraped off and sent to a slag tank or other processing unit for further processing.
There is usually a clear water area at the bottom of the dissolved air flotation tank to collect the clear water that has gone through the separation process. This clear water area is relatively clear water that can be extracted from the system and usually provides a clean water source for subsequent treatment. .
Generally speaking, dissolved air flotation equipment adds flocculant. After the gas and liquid are mixed, tiny bubbles are injected into the water to combine with suspended matter and grease particles and float together, and then remove them from the water through physical separation. .This method is suitable for treating industrial wastewater, kitchen wastewater, water pretreatment in sewage treatment plants, etc., and can effectively remove suspended solids and grease in the water.
