Dissolved Air Flotation and Ultrafiltration Combined Equipment

Dissolved Air Flotation and Ultrafiltration Combined Equipment

Dissolved Air Flotation and Ultrafiltration Combined Equipment integrates dissolved air flotation and ultrafiltration membrane technology into one coordinated water treatment solution. The DAF stage provides efficient pretreatment by separating suspended solids, colloidal particles, oils, grease, algae, and other floatable contaminants, while the UF stage provides fine membrane filtration for the removal of remaining suspended particles, colloids, microorganisms, and other membrane-retained contaminants.

The combination of DAF and UF is particularly useful when conventional clarification alone cannot provide sufficient feedwater quality for membrane filtration. DAF can act as an upstream barrier that reduces the particulate and organic loading presented to the UF membranes. A 2023 review of coagulation-flocculation-DAF followed by low-pressure membranes found that DAF pretreatment can improve product water quality and, in suitable applications, mitigate membrane fouling.

Model NO.	WSZ	Handling method	Biological Treatment
Usage	Industrial, Home, Agriculture, Hospital, Urban	Trademark	Wanze Prosperity
Types	Package, Compact, Small, Mini	Applications	Industrial, Municipal, Domestic, Medical, Ship
Craft	Mbr Membrane, Mbbr, Ao, Aao, Disinfect, Filtration	Features	Water Clarification, Filtration, Purification
Service Life	20 Years	Operation	Automatic
Steel Plate Thickness	>8mm	Function	Remove Cod BOD
Voltage	220V/ 380V/ Customerized	Installation Type	Underground / Onground
Colour	Grey/Silver/Blue/Balck/Customerized	Use for	Mineral, Printing, Chemical, Dyeing, Starch
Material	Carbon Steel, Stain Steel, FRP, PE, PP	Certificate	SGS, ISO
Transport Package	Container Standard Packing	Specification	Carbon steel anti-corrosion
Production Capacity	1000 Sets/Year	Origin	China

How Does DAF and UF Combined Equipment Work?

The system normally starts with preliminary screening or equalization, depending on the source water. Large debris and coarse particles should be removed before entering the DAF process.

The wastewater or raw water then enters the coagulation and flocculation section when chemical conditioning is required. Coagulants destabilize fine particles, while flocculants help form larger aggregates.

A portion of clarified water is recycled through a pressurized air saturation system. When the pressure is released, dissolved air forms microscopic bubbles. These bubbles attach to flocs and suspended particles, increasing their buoyancy and causing them to rise to the flotation surface.

A mechanical skimmer continuously removes the floating sludge. The clarified DAF effluent then enters the UF feed section.

During ultrafiltration, water passes through semipermeable membrane fibers or modules while larger suspended particles, colloids, microorganisms, and other membrane-retained substances are separated from the permeate stream.

This creates a two-stage separation process: DAF for bulk clarification and UF for fine membrane filtration.

Why Combine DAF With Ultrafiltration?

Using DAF and UF together provides different treatment mechanisms rather than relying on a single process.

DAF is particularly effective for separating suspended and floatable materials that can create a heavy fouling load for downstream membranes. UF then provides a much finer physical barrier for the remaining particulate contaminants.

This configuration can be valuable when feedwater contains high turbidity, algae, suspended solids, natural organic matter, oil and grease, or variable particulate loading.

A review of DAF as low-pressure membrane pretreatment notes that the performance of the integrated system depends on feedwater quality, membrane configuration, coagulation conditions, flotation performance, and operating parameters.

DAF Pretreatment for UF Membranes

Membrane fouling is an important consideration in UF system operation. Suspended solids, colloids, organic matter, microorganisms, and other foulants can accumulate on or within membrane surfaces.

The DAF stage provides an opportunity to remove a significant portion of these contaminants before they reach the membrane modules.

This can help stabilize the UF feedwater and reduce the solids burden placed on the membrane system. However, actual membrane fouling behavior depends on feedwater composition, membrane material, flux, temperature, pretreatment chemistry, and operating conditions.

The DAF process should therefore be properly designed rather than treating every UF installation with the same pretreatment configuration.

Suspended Solids and Turbidity Removal

DAF provides rapid separation of suspended and low-density particles. It can be especially useful for water containing fine particles, algae, colloidal material, or solids that do not settle efficiently by gravity.

After DAF clarification, the UF membrane provides a second filtration barrier. Published water-treatment guidance shows DAF can be used as pretreatment for membrane filtration, while UF provides high removal of suspended solids and turbidity under suitable operating conditions.

This combination is useful for applications where stable low-turbidity membrane feed is required.

Oil, Grease, and Floatable Contaminants

For industrial wastewater, DAF can remove free oil, dispersed oil, fats, grease, and other floatable contaminants before the UF stage.

This is particularly useful in food processing, meat processing, dairy, petrochemical, chemical, and other industrial applications where oil and organic solids may contribute to membrane fouling.

Where emulsified oil or very fine colloidal material is present, coagulation and flocculation can be added before flotation to improve particle agglomeration and separation.

Ultrafiltration Membrane Stage

The UF section provides fine membrane filtration after DAF clarification.

Depending on the membrane configuration and operating conditions, UF can remove:

Suspended particles
Fine colloids
Turbidity
Microorganisms
Macromolecules
Residual particulate organic matter
Fine flocculated materials

UF is a pressure-driven membrane process. The treated water passes through the membrane while retained contaminants remain in the concentrate or are removed through backwashing and cleaning cycles.

The UF membrane material, module configuration, pore structure, operating pressure, flux, and cleaning strategy should be selected according to the application.

Typical DAF UF Treatment Process

A complete system may be configured as:

Raw Water/Wastewater → Screening → Equalization → Coagulation → Flocculation → DAF → DAF Clarified Water Tank → UF Feed Pump → Ultrafiltration → UF Permeate → Disinfection or RO → Reuse

The exact process depends on the treatment objective.

For water reuse projects, UF permeate can potentially serve as feedwater for downstream RO where additional dissolved-solids or ionic contaminant removal is required. DAF and UF are also used as membrane pretreatment stages in larger water treatment and desalination trains.

Main Equipment Components

The combined DAF UF system may include:

DAF flotation tank
Coagulation tank
Flocculation tank
Dissolved air recycle pump
Air saturation system
Microbubble release system
Surface sludge scraper
Sludge collection hopper
UF membrane modules
UF feed pump
Backwash pump
Air scouring system
Chemical cleaning system
Permeate tank
Pressure gauges
Flow meters
Automatic valves
PLC control cabinet

Equipment can be arranged as an integrated skid-mounted package or as separate process units connected through a complete treatment system.

Industrial Applications

Dissolved Air Flotation and Ultrafiltration Combined Equipment can be applied to:

Industrial Wastewater Treatment
Food Processing Wastewater
Meat Processing Wastewater
Dairy Wastewater
Beverage Industry Wastewater
Textile Wastewater
Printing and Dyeing Wastewater
Paper Mill Wastewater
Chemical Industry Wastewater
Pharmaceutical Wastewater
Municipal Wastewater Reuse
Surface Water Treatment
Process Water Treatment
Industrial Water Reuse
RO Pretreatment
Desalination Pretreatment

The correct application should be confirmed through wastewater characterization and, where necessary, pilot or laboratory testing.

DAF UF for Water Reuse

For water reuse applications, the DAF stage can reduce particulate loading while UF provides a more refined membrane barrier.

A downstream RO system may be added when the project requires removal of dissolved salts, hardness, specific ions, or other dissolved contaminants that UF does not normally target.

This creates a multi-barrier treatment train such as:

DAF → UF → RO → Disinfection → Reuse

The actual configuration should be selected according to source-water quality and the intended reuse application.

Compact and Automated Treatment Design

Combining DAF and UF can create a compact treatment train compared with using multiple independent clarification and filtration processes.

Automation can be used for DAF recycle pumps, chemical dosing, flotation sludge removal, UF filtration cycles, backwashing, pressure monitoring, flow control, alarms, and chemical cleaning.

A PLC-based control system can coordinate the two treatment stages and provide operating data for routine maintenance and process optimization.

Operation and Maintenance

Routine maintenance should include inspection of DAF recycle pumps, air saturation equipment, pressure gauges, flotation skimmers, chemical dosing systems, and sludge discharge equipment.

For the UF section, operators should monitor transmembrane pressure, permeate flow, flux, feedwater quality, backwash frequency, chemical cleaning frequency, and membrane performance.

UF membranes should be backwashed according to the membrane manufacturer's operating requirements. Chemically enhanced backwash or cleaning may be required when normal backwashing is no longer sufficient.

Pretreatment quality is important because excessive solids or organic loading can increase membrane fouling and cleaning requirements.

Why Choose Us?

Our Dissolved Air Flotation and Ultrafiltration Combined Equipment is designed to integrate two complementary treatment technologies into a practical industrial water treatment solution.

We can configure DAF capacity, flotation structure, chemical dosing, sludge removal, UF membrane material, membrane configuration, automatic control, backwashing, chemical cleaning, and downstream RO or disinfection according to project requirements.

The system can be supplied for industrial wastewater treatment, process water purification, water reuse, municipal wastewater polishing, and membrane pretreatment applications.

We focus on matching the process configuration to actual feedwater characteristics rather than using a standard configuration for every project. Pilot testing and wastewater analysis can be used where specific performance targets require verification.

FAQ
1. What Is DAF UF Combined Equipment?

It is a water treatment system that combines dissolved air flotation with ultrafiltration membrane filtration. DAF provides clarification and bulk solids separation, while UF provides fine membrane filtration.

2. Why Put DAF Before UF?

DAF can remove suspended solids, colloids, oil, grease, algae, and other foulants before they reach the UF membranes, helping provide cleaner membrane feedwater.

3. Can DAF UF Treat Industrial Wastewater?

Yes. The combination can be applied to many industrial wastewater streams, including food, dairy, textile, chemical, paper, and manufacturing wastewater.

4. Can DAF UF Remove Suspended Solids?

Yes. DAF removes many suspended and floatable particles, while UF provides an additional membrane barrier for fine suspended particles and colloids.

5. Can DAF UF Remove Oil and Grease?

DAF can remove free and dispersed oil and grease. For heavily emulsified oil, chemical conditioning may be required.

6. Does UF Remove Dissolved Salts?

UF generally does not provide the same dissolved-salt removal as reverse osmosis. RO or another appropriate process may be required when dissolved solids must be reduced.

7. Can UF Permeate Be Sent to RO?

Yes. DAF-UF can be used as a pretreatment train before RO when the overall water treatment design requires further dissolved-contaminant removal.

8. Does the DAF System Need Chemicals?

Not necessarily. However, coagulation and flocculation are frequently used when fine colloids or difficult-to-separate particles require improved flotation.

9. How Is UF Membrane Fouling Controlled?

Proper DAF pretreatment, optimized flux, regular backwashing, chemical cleaning, and continuous monitoring of membrane pressure and flow are important for controlling fouling.

10. Can the DAF UF System Be Fully Automatic?

Yes. PLC control can coordinate chemical dosing, DAF operation, sludge removal, UF filtration, backwashing, cleaning, alarms, and other automatic functions.

11. How Is DAF UF Capacity Selected?

Capacity depends on feedwater flow, peak flow, suspended solids, turbidity, organic loading, oil and grease, membrane flux, treatment targets, and available installation space.

12. Can the Equipment Be Customized?

Yes. DAF tank size, recycle system, chemical dosing, UF membrane modules, pumps, automation, cleaning system, skid configuration, and downstream treatment can be customized for the project.

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