Complete set of air flotation machine device

The complete set of air flotation equipment mainly includes dispersed air flotation, dissolved air flotation (including true air flotation), and electrolytic air flotation. Currently, it has applications in water supply, industrial wastewater, and urban sewage treatment. Compared with other solid-liquid separation equipment, air flotation equipment has the characteristics of less investment, minimal footprint, high degree of automation, and convenient operation and management. In practice, targeted selection and use should be made based on the characteristics of wastewater treatment processes, wastewater quality and quantity.

1. Electrolytic air flotation equipment

Electrolytic air flotation equipment directly electrolyzes wastewater using inert anodes and cathodes. The tiny bubbles of hydrogen and oxygen generated by electrolysis carry the flocculated suspension to the surface of the water. To achieve the purpose of solid-liquid separation.

The bubble size generated by electrolysis is much smaller than that generated by dissolved air flotation and dispersed air flotation, and does not generate turbulence. The device has a wide range of pollutants to be removed. In addition to reducing BOD, it also has oxidation, decolorization, and sterilization effects on organic wastewater. It has strong adaptability to changes in wastewater load, generates less sludge, occupies less land, and does not produce noise. In recent years, it has developed rapidly. At present, electrolytic air flotation equipment still faces problems such as high energy consumption and plate loss, as well as high operating costs, which limit the promotion and use of this equipment.

2. Scattered air flotation equipment

The air flotation equipment relies on the vacuum negative pressure state caused by the centrifugal force of the high-speed rotating impeller to suck in air, which becomes fine air bubbles and diffuses in the water. Bubbles rise from the bottom of the pool to the water surface and adhere to suspended solids in the water, bringing them to the surface. To achieve the purpose of solid-liquid separation. The formed floating slag is continuously scraped out of the pool by a slowly rotating scraper plate. The mechanical shear force of water flow and the large bubbles generated by the diffuser plate (with a diameter of about 1mm) make it difficult to adsorb with small particles and flocs, and instead tend to break the flocs. Therefore, air flotation is not suitable for treating wastewater containing small particles and flocs. The air flotation time of the dispersed air flotation equipment is about 30nim, and the dissolved air volume reaches 0.51m3/m3 (air/water).

The peripheral linear velocity of the rotating impeller is about 12.5m/s. The application scope of this equipment includes small-scale sewage treatment projects such as painting, leather making, oil refining, printing and dyeing, chemistry, dairy processing, fiber production, papermaking, food and beverage, slaughtering, textile, mechanical processing, municipal sewage, etc.

3. Dissolved air vacuum flotation equipment

The supersaturated air in water can be released in the form of fine bubbles during decompression, causing impurities particles in the water to adhere and float up. To achieve the purpose of solid-liquid separation. If air is first pressurized to dissolve in water to form an air supersaturated solution, and then reduced to atmospheric pressure to allow air to precipitate, it is called pressurized dissolved air flotation; If wastewater is aerated under normal pressure and then induced to release dissolved air under vacuum conditions, it is called vacuum air flotation.

Dissolved air vacuum flotation equipment is an air flotation device that dissolves air in water under normal pressure or pressure, and precipitates it under negative pressure. The advantage of vacuum air flotation equipment is that the formation of bubbles, their adhesion to particles, and the upward flotation of bubbles and particle flocs all occur in a stable environment, with a low possibility of floc damage and low energy consumption required for the entire air flotation process. Its disadvantage is that the dissolved gas in water is limited and it is not suitable for wastewater containing suspended solids with concentrations greater than 250-300mg/L; Another disadvantage is the requirement for sealed containers, which also require the installation of scraper machinery inside. The structure is complex, so it is less commonly used in engineering practice. The amount of air that this device may obtain is limited due to the achievable vacuum level (usually operating at a vacuum level of 40kPa), resulting in a very limited amount of fine bubbles that are difficult to operate and maintain due to its complex structure. It has been gradually phased out.

4. Pressure dissolved air flotation equipment device

The pressurized dissolved air flotation equipment pressurizes clean water to (3-4) × 105Pa, while adding air to dissolve the air in the water, and then suddenly reduces it to atmospheric pressure. The air dissolved in the water is separated from the water in the form of small bubbles (with a diameter of about 20-100 μ m), and suspended particles in the water are carried to the surface. Thus achieving solid-liquid separation. Pressure dissolved air flotation equipment is currently a widely used type of air flotation equipment. This device can be widely used for various types of wastewater treatment (especially oily wastewater treatment), sludge concentration, and water supply treatment.

The pressurized dissolved air flotation equipment mainly consists of three parts: air saturation equipment, equipment for air release and mixing with wastewater, and solid-liquid or liquid-liquid separation equipment. According to the types, properties, and treatment efficiency of suspended solids in raw water, it can be divided into three types: fully pressurized dissolved air flotation, partially pressurized dissolved air flotation, and reflux pressurized dissolved air flotation.

At present, pressurized gas flotation is the most widely used method. Compared with other air flotation equipment, it has the following characteristics:

Under pressurized conditions, the air solubility is high, and the number of bubbles used for gas flotation is large, which can ensure the effectiveness of air flotation;

⑵ When the dissolved gas is suddenly released under reduced pressure, the bubbles generated are not only fine, uniform in size, and dense, but also stable and have little disturbance to the liquid. Therefore, it is particularly suitable for solid-liquid separation of loose flocs and small particles;

The process and equipment are relatively simple, easy to manage and maintain;

Especially for partial reflux type, the treatment effect is significant, stable, and can greatly save energy consumption.