WSI International
WSI International
Wastewater Treatment and Equipment


    Dissolved Air Flotation (DAF) Technology

    US Patents *US8632685B2 *US20140175023A1 *US6251287B1 *US6572817B1

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Dissolved Air Flotation (DAF) Systems - The Ultimate Solution for Water Treatment

Dissolved Air Flotation (DAF) systems have become an essential component in the water treatment industry. They are designed to remove pollutants, such as suspended solids, oils, and grease, from wastewater, industrial process water, and other contaminated water sources. The primary objective of DAF systems is to provide high-quality treated water that can be reused or discharged safely into the environment.

The Working Principle of DAF Systems

DAF systems work by creating tiny air bubbles that attach themselves to suspended pollutants in the water. The bubbles lift the pollutants to the surface, where they can be easily removed. The process starts with the addition of a chemical coagulant to the water, which causes the suspended particles to clump together. This makes it easier for the air bubbles to attach to the particles and lift them to the surface.

Once the pollutants have been lifted to the surface, they are removed by a skimming device. The cleaned water is then ready for discharge or reuse. The process is repeated continuously to ensure that the water remains free of contaminants.

The Benefits of Using DAF Systems

There are numerous benefits to using DAF systems for water treatment. These include:

  • High efficiency: DAF systems are highly effective in removing a wide range of pollutants from water. They are capable of removing up to 95% of suspended solids, oils, and grease from water.

  • Cost-effective: DAF systems are more cost-effective than other water treatment methods, such as chemical precipitation and sedimentation. They are also more energy-efficient, as they use less energy to create the air bubbles than other methods.

  • Easy to maintain: DAF systems are simple to maintain and require minimal operational attention. They are also easy to operate, making them ideal for use in remote locations where maintenance and repair services may not be readily available.

  • Environmentally friendly: DAF systems are environmentally friendly, as they do not produce any harmful by-products or discharge pollutants into the environment.

CAD Drawings of Standard DAF Systems

Standard Designs (POC, and Demensional Drawings):

> 50 GPM

± 100 GPM

± 250 GPM

± 500 GPM

< 1000 GPM


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Current Fabrication Time: 8 Weeks or Less!

Packaged DAF Systems with Integrated Controls, pH Balance Tank and Sludge Holding Tank

Packaged Dissolved Air Floatation Unit (DAF)
Stainless Steel Dissolved Air Floatation Unit (DAF)

DAF Stainless Steel Design

WSI DAF Systems, will be constructed from 3/16” stainless steel plate. The body is constructed with three independent cone bottom collection hoppers with pneumatically operated valve connection point.  All process chambers of WSI DAF units are fabricated into the system. This includes: Two DAF floatation zones, scum collection hoppers with rail system, and effluent weir chamber. 

What We Are Working On

DAF Mobile Phone Controls

DAF Electrical & Controls

The system is provided with a main control panel that houses the Variable Frequency Drives (VFDs), motor starters, relays, Programmable Logic Controller (PLC) and Human Machine Interface (HMI). The VFDs are configured for the torque share operation mode. The panel enclosure is NEMA 4X with a side mount air conditioning unit to protect the control components in a wet, washdown environment. The HMI provides the press operational information in a graphical format to the operator and allows the adjustment of set points and parameters. The panel is provided with physical Hand-Off-Auto switches for all motors, enabling the system to be operated in an automatic mode as well as manually and overriding the logic controller. 

When in automatic mode, the logic controller will flow pace the polymer injection rate to meet the operators desired dosage per feedback from the sludge magnetic flow meter.
Nikuni DAF Pump

Nikuni DAF Pumps

The Nikuni DAF pump is a high flow micro-bubble generator made from 316 stainless steel. The Nikuni pump is a highly precise pumping mechanism that generates microbubbles by utilizing two hydro-dynamic principles: negative pressure sucking both air and water simultaneously from each port; air effectively mixed into water; which properly produces pressurized nitrogen-enriched discharge.

Nikuni DAF Pump Seal
DAF Saturation Tank

Simple DAF Saturation Tank

The saturation tank is constructed from 304L Schedule 10 pipe and is designed and fabricated in such a way that coarse bubbles from the air enriching process are collected and discharge into the DAF effluent chamber. This prevents coarse bubbles from disrupting the sludge blanket that is formed in the floatation zone. 

Micro Bubble Generation

The Micro bubbles generated from the Nikuni pump system are dispersed into the DAF by three to six precisely located white water injectors. These injectors are constructed out of 1.5” schedule 10 304 stainless steel pipe. These pipes run the width of the DAF and have a proprietary grooved design opening for proper distribution and enhanced flocculation. Each injector has a diaphragm valve that will allow the operator to dial in the precise distribution of white water. 

The white-water injectors play a crucial role in the DAF system as they are responsible for creating a homogenous mixture of micro bubbles and wastewater. This mixture is then subjected to a flocculation process which leads to the formation of larger flocs. The precise control over the distribution of white water allows for optimal flocculation and maximum separation of suspended solids. The use of 304 stainless steel in the construction of the injectors ensures durability and resistance to corrosion in harsh wastewater environments. The proprietary grooved design of the injectors also enhances the mixing of the micro bubbles and wastewater, leading to improved performance of the DAF system.

Dissolved Air Floatation (DAF) Solids
Dissolved Air Floatation (DAF) Microbubbles
Dry Solids from Dissolved Air Floatation (DAF) Unit
Dry Solids from WSI DAF System
DAF Rake System

DAF Surface Skimmer System

The skimmer system is comprised of two parallel lengths of ultraviolet stabilized glass reinforced Nylon 6/6 chain with stainless steel paddles and buna rubber wiper assemblies. The skimmer system is powered by a helical worm gear motor that is VFD controlled.  This allows the operator to have precise control over the speed at which the paddle skims across the top layer of the DAF. This is important as to not disrupt the gentle nature of the sludge blanket that is formed in the floatation zone of the DAF.  The paddle is the width of the DAF body and gently pushes the skimmed sludge up a stainless steel beach and into a collection hopper.  The ends of the stainless steel paddles are supported by UHMW blocks which ride on internal rails. This allows the paddles to interface the sludge blanket at a consistent elevation along the length of the DAF and gently collect the thickened sludge, pushing it into the sludge hopper.