Dissolved Air Flotation

Filtration has been used in water treatment processes for decades and still is one of the most popular methods of treatment of potable water. When solids loadings or contamination levels are high however, media filters often suffer as backwashing frequencies increase considerably ultimately reducing the throughput of the plant. 

A DAFF system is a combined filtration flotation system that incorporates both processes into a single packaged unit.

After traditional flocculation stages, dissolved air is injected into the waste forcing the majority of solids to rise to the surface of the vessel. The supernatant water then flows through the filter media where it undergoes final treatment and disinfection processes.

The final stage of the treatment process is storage and distribution. The water travels through the pipe network to large storage tanks ready for use in the Ballarat water supply system.

Ovivo can design DAFF systems capable of handling flows from 0.1ML/ day to 20ML/day. Engineering is carried out using the latest AutoCAD software.

WAS (Waste Activated Sludge) is basically the excess sludge that is removed periodically from biological treatment processes. This excess sludge is generally pumped from the base of the biological reactor or clarifier and is low in solids content, typically 0.3-1.5% solids.

The function of the DAF system is to thicken the solids prior to dewatering. Sludge thickening using the DAF system will reduce the hydraulic load on the dewatering machine and produce a more stable drier sludge.

Subject to the use of polymer, the Ovivo DAF system will thicken the solids to up to 4.5% DS.

Ovivo WAS DAF - Queensland

Unlike DAF systems designed to treat industrial wastewater, (which are generally sized based on flow rate and solids loadings), Waste Activated Sludge DAF systems consider several more variables. The sizing of a WAS DAF system takes into account the surface mass loading rate (i.e. the mass of solids entering the DAF system as a function of the DAF surface areas.  The surface volume loading rate which is a function of the actual fluid flow into the DAF system and the air to solids ratio which influences the design of the recycle system.

A WAS DAF system are generally deeper than industrial DAF systems and when compared to volume, are considerably larger. 

Ovivo WAS DAF systems are fabricated in either stainless steel, mild steel or concrete and all engineering and design is conducted in house.