Dissolved Air Flotation (DAF)
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 heart of our system is the Krofta ADT which is used to saturate air into the recycled treated water. At atmospheric pressure, this creates millions of micro bubbles in the size range of 30-50 micron.
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.
Engineering
Materials
Energy
Automotive
How Krofta DAF Works
1
Coagulation
2
Flocculation
3
Air Saturation through ADT
4
Microbubble Generation (30–50 μm)
5
Bubble-Particle Attachment
6
Flotation & Separation
7
Sludge skimming & Removal
8
Clarified Water Collection
ADT Technology
Krofta’s Air Dissolving Tube (ADT) produces extremely fine microbubbles (20–50 μm) that efficiently attach to suspended solids, oil droplets, grease, algae, and fibers, ensuring superior flotation performance.
Typical Removal Performance
| Parameter | Removal Efficiency |
|---|---|
| TSS | Up to 95% |
| Free Oil | Up to 95% |
| Emulsified Oil | Up to 95% |
| Suspended COD | Up to 80% |
| Suspended BOD | Up to 80% |
| Fiber Recovery | Up to 98% |
One Technology. Five Proven Solutions.
| Model | Type | Capacity |
|---|---|---|
| Minicell | Compact Circular DAF | Up to 712 m³/hr |
| Supercell | High-Rate Circular DAF | Up to 2692 m³/hr |
| Sedicell | Flotation + Sedimentation DAF | Up to 4000 m³/hr |
| Megacell | Horizontal Lamella DAF | Up to 2000 m³/hr |
| Unicell | High HLR Rectangular DAF | Up to 700 m³/hr |
| Unicell-R | High HLR Rectangular DAF | Up to 6000 m³/hr |
We offer 5 different DAF models, selection of which is based on the inlet parameters and application after being studied by our technical experts
Legacy Milestones
Decades of Innovation & Trust
1983
Company Foundation & DAF Roots
Krofta Engineering Limited (KEL), India was incorporated in India as a joint venture with Dr. Milos Krofta. Dr. Milos Krofta was the inventor of the DAF technology. This is why the Krofta name is synonymous with DAF
1995
The Sedicell DAF Breakthrough
Krofta introduced the Sedicell DAF, a breakthrough flotation system that revolutionized water and wastewater treatment. Delivering exceptional solids separation and resource recovery, the technology achieved remarkable success worldwide and became a trusted solution for industries seeking efficient and sustainable treatment processes.
1999
Megacell Technology Patented
The Krofta Megacell Patent was officially issued, marking a significant advancement in flotation technology and reinforcing Krofta’s commitment to innovation in water and wastewater treatment.
2007
European Alliance for Belt Presses
KEL India successfully begins a technical collaboration with AJV Engineering Ky., a company from Finland for the design, engineering, manufacturing and sale of the Belt Filter Press (L series).
2009
UK Collaboration for Oil Separation
KEL India successfully begins a technical collaboration with Stetfield Separators, a United Kingdom based company for the design, engineering, manufacturing and sale of TPI and CPI oil water separators
2019
Megacell DAF India Launch
KEL India, successfully launches Megacell DAF in India. With over 150 installations in the first 2 years alone Megacell has seen great success not only in the pulp and paper industry but in various applications such as powerplants, desalination and textiles.
2019
Indigenous Sludge Innovation (BFP-T)
KEL India also successfully launches the initial model of the Triple Wire Belt Filter Press (BFP-T). An in-house innovation to solve the challenges of sludge de-watering at a much more economical price point. The BFP-T aims to reduce imports and build trust among the industry for made in India products, and challenge the globally existing machines of similar capacities and size
2021
Expansion into Municipal Disc Filters
KEL expanded its technological portfolio by developing Disc Filters specifically for municipal wastewater treatment applications. Designed to deliver high-quality effluent with a compact footprint, KEL Disc Filters provide efficient removal of fine suspended solids, supporting water reuse, regulatory compliance, and environmental sustainability.
2025
Launch of Next-Gen SAF® Technology
KEL India, in collaboration with Heron Innovators, presents SAF®—a breakthrough advancement in flotation technology, setting new standards for efficient and sustainable water treatment
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