Daftech Engineers Pvt.Ltd.

• DAFTECH’s Dissolved Air Flotation System is an excellent choice for reliable wastewater clarification in an easy-to-install-and-use package.
• DAFTECH’s Dissolved Air Flotation Clarifier can be configured for a tremendous variety of wastewater characteristics.
• DAFTECH’s Dissolved Air Flotation Clarifier comes standard with a surface skimmer of adjustable speed, an automatic bottom sludge purger and in fluent / effluent and floated sludge chambers.
• DAFTECH’s Dissolved Air Flotation Wastewater clarifier can handle difficult wastewater streams with combinations of chemical inputs including liquid poly electrolytes, dry powders and organic and inorganic coagulants.

The fact that dissolved air flotation clarifiers or dissolved air flotation units (with 3 - 5 minutes of detention time) can replace sedimentation (with 2 - 3 hours of detention time) for clarification, has been overlooked by environmental engineers for many decades. Modern high rate DAF clarifiers have advanced to such an extent that they could overshadow conventional settling clarifiers in wastewater treatment.

DAF hydraulic loading has increased from 1 L/m2.s to 2.5 L/m2.s and for a triple stacked unit to 7.5 L/m2.s. The detention time has decreased from 30 minutes to 3 minutes. Air dissolving is improved and now requires only 10 seconds retention time in the air mixing tube instead of the previous 60 seconds. The smaller size and weight of a modern DAF unit allow for inexpensive construction and flexibility of erection using prefabricated units. The availability of excellent flocculating chemicals gives a high stability of operation and high clarification degree.

DAFTECH Floatcells are circular in shape, ranging in diameter from 1.2 to 16.8 meters and a liquid depth of only 0.65 meter. The complete set up consists of a flotation tank, feed pump, pressure pump, compressor, air mixing tube, chemical feed system and a spiral scoop for collection and removal of floated sludge.

The inlet, outlet and sludge removal mechanisms are contained in the central rotating section. This section and the spiral scoop rotate around the tank at a speed synchronized with the flow. The system is operated in the recycle flow pressurization mode where a portion of clarified effluent (25 - 30 percent) is continuously recycled from the DAF tank to the air mixing tube at about 6.5 bar pressure. After pressure release, the aerated water is mixed with the influent flow just before the inlet to the distribution duct that moves with the same velocity, but in opposite direction to the incoming flow thus creating a quiescent state in the flotation chamber. Fine bubbles generated in this manner attach to the suspended particles and make them float to the surface.

The spiral scoop takes up the floated sludge, pouring it into the stationary center section where it is discharged by gravity. Clarified water is removed by extraction pipes, which are attached to the moving center section and discharged. Wiper blades attached to the moving distribution duct scrape the bottom and the sides of the tank and discharge settled sludge into the built-in sump for periodic purging. Variable speed geared motors drive the rotating elements and scoop. Electrical current for the geared motors are fed from a rotary contact mounted on the central shaft.

The separation efficiency of Total Suspended Solids in a DAF cell depends substantially on the generation of uniformly sized microscopic air bubbles. 

A part of the clarified water, generally 25 to 30% of the feed rate, is pressurized through a centrifugal pump to about 65 meter head and let into a cylindrical Air Mixing Tube through a nozzle at one end. The nozzle is so oriented inside the tank that the jet of water churns spirally along the inside wall of the tube forming a vortex along the central axis of the tube.

Into this tube is brought compressed air which passes through a microscopically porous medium placed adjacent to the inside wall of the tube.

The tube produces a saturated air-water mixture because the rate of absorption of any gas in a liquid is directly proportional to the pressure in which the dissolution takes place.

The air-water mixture that comes out of the other end of the tube passes through a pressure release valve where the pressure is reduced to the level of the incoming wastewater feed. At this stage, air bubbles of 30 - 50 microns are produced profusely which get released into the wastewater thereby giving the necessary buoyancy
to the suspended solids to rise to the surface of the water in the flotation tank.

A quiescent state is an absolute necessity for good flotation. This is achieved by ensuring zero velocity of the wastewater when it enters the flotation tank.

The feed of wastewater premixed with depressurized recycle stream is led into the main tank through a distribution tube with adjustable nozzles. It is then discharged into the tank through baffles and then a turbulence arrester. The rotational velocity of the incoming wastewater into the tank is counterbalanced by the mechanical movement of the distribution tube in the opposite direction but at the same speed. This ensures quiescent condition and minimum turbulence.

DAFTECH Floatcells are designed with a retention time of 3 minutes. The equipment therefore is much more compact than rectangular DAF clarifiers of 15 to 30 minutes of retention and occupies only half of the floor space.

• FLOATCELL DISSOLVED AIR FLOTATION CLARIFIER

• DAF FLOATCELL FLOW DIAGRAM
• LEGENDS

  1	Wastewater Inlet	7	Floatcell Wall	13	Wastewater Pump
  2	Clarified Water Outlet	8	Tank Wall Support	14	Air Compressor
  3	Floated Sludge Outlet	9	Rotating Tank Wall	15	Flocculant Feed Point
  4	Clarified Water Recycle Outlet	10	Level Control Weir	16	Pressure Release Valve
  5	Rotary Joint	11	Spiral Scoop	17	Purge Valve
  6	Spiral Scoop Shaft	12	Recycle Pump	18	Sample Point

DAF clarifiers, industrial wastewater treatment plants, find applications in pulp and paper mills, recycled fibre mills, drinking, food processing, dairies, textile mills, municipalities and others. Total suspended solids removal to below 50 ppm of filterable solids and thickened sludge consistency of 2-4% are indicative of the efficient operation of these industrial wastewater treatment plants.

Here is an indicative list of applications of DAF:

• Fibre Recovery in Pulp and Paper Mills
• Ballast Water
• Carbon Black Production
• Solids Recovery
• Fish Processing
• Soap Industry
• Municipalities
• Meat Processing and Packing
• Primary Clarification
• Tanneries
• General Food Manufacturing
• Secondary Clarification
• Snack Food Production
• Vegetable Oil Processing
• Dairies
• Rendering Plants
• Laundries
• Breweries
• Canning Water
• Water Recycling
• Algae Removal
• Bakeries
• Car Wash Operations
• Poultry Processing
• Confectionery
• Textile Effluent
• Refineries
• Potato Processing
• Starch Removal
• Pharmaceuticals
• Steel Production
• Fertilizer Effluents
• Coal Tar Pitch Processing
• Tetra Pack Effluents
• Cheese Production
• Slaughter Houses
• Heavy Metals Removal
• Membrane System Pre- treatment
• Paint Shops
• Jute Mill Effluents
• PVC production
• Palm Oil Refining
• Air Mixing
• Waste Oil Processing
• Ice Cream Production
• Non-woven Effluents
• Pulp Mill Effluents
• Fruit Processing
• Sewage Treatment
• Kitchen Effluents
• Coolant Clarification
• Rice Mill Effluents
• Polyester Production
• Rubber Effluents
• Polymer Production
• Augmentation of Depurator Efficiency
• Farm Effluents
• Cosmetics Production
• Wool Scouring Effluents
• Gelatin Production

Our Dissolved Air Flotation system has the following advantages :

• Low capital and operational costs
• Continuously self-cleaning
• Totally integrated
• Minimal maintenance
• Pre- engineered
• Stable operation
• Space saving and low foundation costs
• High quality clarified water
• Simple installation
• Superior performance
• High chemical efficiency
• Easily relocatable

Daftech Engineers Pvt. Ltd. is a wastewater clarifier company that meets the needs of clients all over the world for Dissolved Air Flotation (DAF) Clarifier. Since our inception, we have been continually improving the design of our circular DAF units known as Floatcells. We manufacture and export complete line of wastewater clarifier, circular DAF wastewater clarifier with nominal capacities of 5 m³/hr to 2019 m³/hr. Today DAFtech is known for its expertise in design, installation, operation, maintenance and troubleshooting of DAF water clarifier around the world over.

DAFtech’s philosophy has been to work with various industries in developing a new generation of Dissolved Air Flotation Water Clarifier to provide efficient and cost effective solutions for recovering valuable solids from process streams and clarifying their effluents.

With quality raw materials, manufacturing expertise and experienced personnel as our pillars of strength we provide quality products at competitive price. Our commitment to excellence has taken us miles ahead of our competition. We have a worldwide presence of installations and have been exporting our Floatcells to the international markets.

North America, South America, Europe, Africa, Middle East, Far East and South East Asia.