WPL Dissolved Air Flotation (DAF)

For industrial wastewater treatment a Dissolved Air Flotation (DAF) system can help achieve compliance for sewer discharge and reduce costs associated with trade effluent charges.

The primary objective of a DAF treatment system is to reduce Chemical Oxygen Demand (COD) loading by the removal of high COD contaminants including fats, oils and greases, colour, organic matter and colloidal material. A reduction of up to 90% of COD and suspended solids can be achieved with a dissolved air flotation system. The DAF system can be used with or without the addition of chemicals; depending on the waste type, chemicals can further enhance performance.

Installed across Europe at municipal wastewater treatment facilities, our dissolved air flotation systems have been used most efficiently for minimising sludge waste from activated sludge and suspended growth biological treatment processes.

Dissolved air flotation (DAF)  is also used in treating industrial wastewater effluents from petrochemical, chemical plants, pharmaceutical, paper mills to industrial facilities.

 

Features and Benefits of the WPL DAF Treatment System:

Highly efficient

  • Improved efficiency with numerous sampling and injection points

 Low maintenance

  • Reinforced plastic components reduce wear and corrosion
  • White water system utilises a pressure vessel to negate the need for diffusers within the flotation tank

Small footprint

  • The DAF treatment system only requires a small footprint in comparison to other technologies

Quality robust design

  • Main structural components are manufactured in grade 304 stainless steel for added corrosion resistance (higher specification can be supplied if required)
  • PVC coil pipe flocculator eliminates corrosion

Various applications for industrial/trade effluent

  • Can cope with variations in influent wastewater quality and flow

 Transportable

  • The DAF system comes complete with options for access and portability

Typical WPL DAF industrial wastewater applications include:

  • Abattoirs, meat and poultry wastewater treatment
  • Brewery, winery and soft drink manufacture wastewater treatment
  • Baking and confectionery, ready meals and vegetable production and packaging manufactures wastewater treatment
  • Commercial laundry wastewater treatment
  • Cosmetics manufactures production and packaging wastewater treatment
  • Dairy inc milk, cream, yoghurt and cheese processing and packaging wastewater treatment
  • Fish processing wastewater treatment
  • Paper mills wastewater treatment
  • Petrochemical wastewater treatment
  • Pharmaceutical wastewater treatment
  • Textile manufacture wastewater treatment
  • Waste recycling centre wastewater treatment

The WPL DAF system is ideal for:

  • New projects
  • Existing plant upgrades
  • Replacement plants

WPL DAF System Specification Information

Image of technical drawing of DAF (Dissolved Aerated Flotation System)

Image of DAF (Dissolved Aerated Flotation System) specification table

Larger WPL DAF units can be bespoke manufactured on request


How does a Dissolved Air Floatation system work

The WPL Dissolved Air Flotation system is a purely physical process which operates on a simple design philosophy. Incoming effluent may require pre-treatment as necessary; for example the addition of chemical coagulant(s) and/or flocculant(s) may be required with associated mixing and coagulation/flocculation stages. Adjustment of pH may also be necessary to ensure optimum operating conditions.

The incoming effluent enters the flotation vessel where it comes into contact with recycled, treated effluent (sometimes termed white water). The percentage of the total effluent flow into which air is dissolved under pressure and subsequently recycled will be determined by several factors.Increasing the pressure within the vessel where the air is being dissolved ensures that a higher concentration of air dissolves into the liquid phase than is possible at atmospheric pressure.

Once this saturated effluent enters the flotation tank, the pressure is released back to atmospheric pressure. This immediately results in the recycled flow becoming supersaturated, generating micro bubbles as the dissolved air comes back out of solution.

These bubbles attach to, and form within, the solids or chemical flocculants entering the vessel, causing them to float to the surface where they are retained and subsequently removed by a mechanical skimmer.

Within the rectangular flotation tank, the skimmer mechanism consists of a series of paddles or flights which run on a plastic corrosion-resistant chain, and skim just below the surface of the tank removing the float into a trough for recovery of the sludge. To eliminate the risk of sludge build-up on the flotation tank floor, the design may also incorporate a floor scraper.


Why industrial wastewater treatment is as challenging as it is varied?

Simon Kimber, discusses why industrial wastewater is as challenging as it is varied, which is why careful assessment and customised solutions are required.

Industrial processes can produce effluents that are challenging in terms of their strength, variability and composition. Careful assessment of the physical, chemical and biological characteristics of the load can deliver a cost-effective and efficient treatment process.

Read full article

Image of WPL dissolved air flotation DAF wastewater treatment tank with engineer