Dissolved Air Flotation Units DAF Wastewater Treatment Plant Equipment

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Dissolved Air Flotation Units - DAF

Water and Wastewater Treatment Plant Equipment

Beyond full plant planning and construction, we supply CE certificated dissolved-air flotation (DAF) units. Air Flotation is applied to the clarification of wastewater to meet effluent discharge requirements; to recovering suspended material or for reclaiming water for reuse; and to the thickening of slurries and sludges prior to disposal, further treatment or dewatering. Dissolved-air flotation is best applied to remove materials and solids that normally settle slowly, persist in remaining in suspension, or have a tendency to float.

The available models cover a great range of capacities suitable for any requirements
(from 1 to 80 m3/hour and more)

The DAF unit is applyed in wastewater treatment plants in dairy, meat processing factories mechanical productions with oil and grease poluted wastewaters, and many other as well.

Flotation is a process to separate suspended or emulsified matters from the liquid phase floating them through the action of a rising gas stream, normally air. The gas can be, either injected, or dissolved under pressure into the water. In the first case (IAF or induced air flotation), air is simply introduced into the water by a compressor and air diffusers. The air bubbles diameter varies from 1 to 5 millimetres, according to the used diffusers. In the second case (DAF or dissolved air flotation), air is dissolved under pressure into the water to produce, once pressure is released, air bubbles with a diameter of 20 to 50 microns that saturate the whole liquid mass. The result is the formation of a light particulate that quickly rises forming a layer on the surface of the clarified water. The pressurising system used in our DAF units (continuous circulating of the mixture from the group of saturation to the one of dissolution) allows to obtain over saturated water/air mixtures with low power and low energetic consumption. Moreover, this system allows to introduce air to an independent pressure from the working pressure of the saturation group, avoiding thus the installation of additional compressors.Wastewater to be treated enters a reaction coil particularly shaped to allow a thorough contact and complete mixing with the dosed chemicals.

Dissolved Air Floatation Units DAF Water and Wastewater Treatment Plant Equipment

Typical Applications:

Chemical processing plants
Pulp and paper mills
Oil water separation in the oil industry and polutions in wastewater
Food processing industry, dairy, meat processing factories, sweets, destillery, wine production and farms
Textile and other industries

The dosage of chemicals in the reaction coil is carried out with high reliability systems and high performances metering pumps. The control of the pH is always on-line with industrial instruments of great precision and electrodes of combined type in solution gel. The water/air mixture is injected after the chemicals dosage in many different points of the reaction coil and flotation tank, to obtain the most uniform possible distribution of its concentration in the fluid mass and an intimate contact with the flocks to be removed. In this way, already in the reaction coil the flocks produced by the reaction with the dosed chemicals absorb air particles, to advantage of the reliability of the process and of their rising speed.
The flow of the saturated water/air mixture and wastewaters conditioned with the chemicals, is then introduced in the flotation tank through a conical profile ejector to increase in a progressive way the rising speed of the solid flocks stuck to the air bubbles. Thus, a thick layer of floated materials grows on the surface of the flotation tank and it is removed by a scraper. The conveying course of the floated materials to the collection hopper, is built with a curved profile connection, so to facilitate the water-drainage and achieve a high concentration of dry matter into the discharged sludges.
A specially shaped telescopic valve collects clear water and allows to control the level into the flotation tank, thus the quantity of sludge to be removed. The water flow speed is calculated non to disturb the rising of lighter materials and the sedimentation of the heavier. Settled materials are discharged through an automatic valve.
The software controlling and ruling the entire process is of high reliability (written for PLC SIEMENS, but exportable also to other PLC on request) and guarantees always the best conditions and performances of treatment. A remote control of the operations with a SCADA interface is available as option, as well as the transfer of all the working data on a PC with a TCP/IP protocol.
These and other constructive particulars, make these machines particularly fit for the treatment of industrial wastewaters, in particular from industries of the oil, mechanics, galvanic and textiles, refineries, as well as any alimentary industry as dairies, meat processing industries, sweet and chocolate industries, wine, beer and liquors industries.

The available models cover a great range of capacities (from 1 to 80 m3/hour and more) and may be completed with modular units for a complete treatment of wastewaters, such as chemical oxidation, filtration on resins, quartzite and activated coal, units for biological treatment, etc.

All the units are completely built in stainless steel AISI304 made to last, other materials on request.
DAF units are supplied ready to be installed, on request installed, starter and tested by our technicians.