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DAF (Dissolved air flotation)

Dissolved Air Floatation
Dissolved Air Flotation (DAF) is a physio-chemical process of solid and liquid separation. This technology was developed by Krofta. It is often used in the pre-treatment or primary stage of a waste water treatment plant to initiate suspended solids removal in the system. Krofta has also achieved success with using our DAF as a secondary clarifier to reduce properties such as colour and turbidity.
The system involves the Krofta DAF main tank, Krofta Air Dissolving Tube (ADT), chemical dosing system, recirculation pump and an air compressor. Our DAFs can be constructed in fully metallic structures with any type of coating to meet client requirements. Further, we recommend civil tanks with metallic internal parts for very high flow rates.
The application of Dissolved Air Flotation is to separate solids from liquid,
such as suspended solids, oils, fats and grease with the help of micro bubbles. These bubbles formed in the Krofta ADT attach themselves to light weight solid particles and rise to the surface of the DAF main tank. These solid particles then form a top layer of scum which are either scrapped by blades and removed from the top by a paddle wheel, in the case of our rectangular DAFs, or scooped out and removed by our scoop in the case of our circular DAFs.
The heavier Solid particles settle at the bottom of the main DAF tank and are periodically removed with the help of timer activated purge valves. The treated water passes through the middle and passes out from the outlet nozzle.
Krofta DAF systems are designed to handle high total suspended solids (TSS) and Fats Oils and Grease (FOG) loading. We can treat a range of water flow rates starting as low as 5 m3/hr going up to over 1000 m3/hr with a single DAF unit. This is also done with the help of flocculants and coagulants which are to be dosed as per the rate and quantity mentioned by our engineers for optimal results. We additionally also offer completely automated chemical dosing systems with agitators. Additionally, Krofta DAF’s do not need pipe flocculators since we use inline dosing methods, however, if the client specifically requires it, we do design and manufacture them as well.
The benefits of using our floatation unit with our ADT are:
  • Entire process of air saturation takes only approximately 12 seconds
  • Krofta ADT has a small footprint and easy O&M
  • Micro bubbles lead to very high solids removal efficiency
  • Other air systems may choke in the presence of TSS > 2000 mg/L, however, Krofta DAF systems give highly efficient solids removal at much higher TSS levels.
We offer 5 different DAF models, selection of which is based on the inlet parameters and application after being studied by our technical experts
Rectangular
Circular