Dissolved air flotation

 DAF  is a water treatment process that clarifies wastewaters (or other waters) by the removal of suspended matter such as oil or solids. The removal is achieved by dissolving air in the water or wastewater under pressure and then releasing the air at atmospheric pressure in a flotation tank or basin. The released air forms tiny bubbles which adhere to the suspended matter causing the suspended matter to float to the surface of the water where it may then be removed by a skimming device.

Dissolved air flotation is very widely used in treating the industrial wastewater effluents from oil refineries, petrochemical and chemical plants, natural gas processing plants, paper mills, general water treatment and similar industrial facilities. A very similar process known as induced gas flotation is also used for wastewater treatment. Froth flotation is commonly used in the processing of mineral ores.

In the oil industry, dissolved gas flotation (DGF) units do not use air as the flotation medium due to the explosion risk. Natural gas is used instead to create the bubbles.

The feed water to the DAF float tank is often (but not always) dosed with a coagulant (such as ferric chloride or aluminum sulfate) to flocculate the suspended matter.

Some DAF unit designs utilize parallel plate packing material, lamellas, to provide more separation surface and therefore to enhance the separation efficiency of the unit.

 1,Introduction
  Dissolved air flotation machine (DAF) is manufactured by our factory and mainly used for solid-liquid separation and liquid-liquid separation. Flotation device will produce large amounts of tiny bubbles by dissolved gas and release system in the water, to make the adhesion in the waste water and water close to the density of solid or liquid particles, causing the whole condition of density smaller than water, and depend on the ascend to the surface flotage, so as to achieve the purpose of the liquid-solid separation, liquid-liquid separation.

2. Work Principle:

 The air will be send by air compressor into air tank, then take in air dissolved tank by jet flow device, the air will be force to dissolve into water under 0.35Mpa pressure and forming dissolved air water, then send to air flotation tank. Under the circumstance of sudden release, the air dissolved in water will be dissolve out and form vast microbubble group, which will be fully contact the flocculating suspended matter in sewage, the suspended matter was sent by pump and flocculation after adding medicine, the ascending microbubble group will adsorb in the flocculated suspended matter, made its density reduce and floated to water surface, thus reach the purpose of removing SS and CODcr etc.

3.Characteristics

 1).Dissolved air pump edge bibulous the edge is inspiratory, pump pressurized mix within, gas to liquid efficient dissolving, small bubbles than 30 um.

2).Low voltage operation, the dissolved gas efficiency is as high as 99%, release rate as high as 99%.

3).Tiny bubbles and suspended particles of efficient adsorption, improve the SS remove effect.

4).Dissolved gas water dissolving efficiency 80-100%, than traditional dissolved gas floating high efficiency three times.

5).Pressure-capacity curve smooth, easy to achieve automatic control, easy to operate, easy maintenance, low noise.

4. Main Structure

 1),Air flotation machine:steel structure, it is the main body and core of DAF, which inside is composed of releaser,uniform distribution device,sewage pipe,outlet pipe,sludge tank and scraper system etc.

Releaser set in the central of air flotation machine, it is the key parts of producing microbubbles. The dissolved air water from dissolved air tank is fully mixed sewage in here, suddenly release, producing vigorous agitation and vortex, then form diameter 20-50UM microbubbles, it adhere to flocculating constituent in sewage, thus reduce the flocculating constituent proportion and ascend, cleaning water will be separated out thoroughly. Outlet pipe uniform distribution the bottom,and via 1pc erect main pipe connect to top overflow, overflow exit equipped with water level regulating handle, convenient to adjust water level in tank,. Discharge pipe install in bottom of tank, used to discharge sediment deposit in tank bottom.  The tank body equip with sludge tank, the scraper set in the sludge tank, the scraper rotation constant, continuous scrape the floated sludge into sludge tank, then flow automatically into sludge pond.

2)Dissolved air system is mainly composed of dissolved air tank, air storage tank, air compressor and high pressure pump, dissolved tank is the critical parts of system, its function is realize water and air fully contact , speed up air dissolve, which is a closeness Withstand Voltage steel tank, its inside equip with baffle plate,sleeve, to speed up air and water speed, improve  dissolved air efficiency.

3) Chemical agentia: steel round tank, used to dissolve storage liquid medicine.

  5. Application Scope :

   Papermaking wastewater treatment and fiber recycling, printing and dyeing wastewater treatment, electroplating, etc with heavy metal ions wastewater treatment, oily wastewater treatment, tannery wastewater treatment, chemical wastewater treatment, paint wastewater treatment, food waste water treatment, the biological treatment of mud and water separation, low turbidity water treatment, including algae surface water treatment, and a variety of other wastewater solid, liquid separation etc. 

6. Model and parameters