Dissolved Air Flotation in Filter (DAFF) or Dissolved Air Flotation (DAF)

DAFF has found wide acceptance in Australia - particularly during the 1990's -2000's. DAFF is now regarded as the process of choice. The process offers a very high level of stability, plant availability and water quality performance for potable and secondary waste water treatment.

DAFF or DAF clarification is particularly suitable for :

• Colder waters,
• Algae laden water,
• Waters with taste and odour problems,
• Waters with significant iron,
• Waters with low total alkalinity (to support the coagulation process),
• Raw water with slow settling floc (not supported by sedimentation process),
• Lower turbidity waters (< 80 NTU typical)

The process is high rate relative to sedimentation. It offers particularly robust, trouble free operation with a relatively small footprint.

Recycle filtered water is directed to an air saturator operating at the compressed air connection regulated pressure (600-800 kPa typ.).

Dissolution of compressed air at the recycle stream is effected to saturation levels at the set compressed air pressure.

Saturator outflow is directed to the flotation cell inlet and dispersed across the bottom reaches of the cell inlet chimney.

Recycle dispersion valves and proprietary cones facilitate saturated air dissolution in the form of micro bubbles  which uniformly contacts the incoming flotation cell floc particles. The micro bubbles attach to the flocs and suspended matter and float to the flotation cell surface for removal as a concentrated sludge float.

With flotation, large, fully developed, rapid settling floc (as required for sedimentation) is unnecessary. Less floc development time is necessary and less chemical coagulant is used hence there is less demand for any supplementary alkalinity to support the coagulation process.

This has obvious advantages - lower chemical costs, smaller footprint and improved process stability/robustness.

Float removal is arranged periodically by low pressure air blowers with hydraulic overflow assistance.

Aquagenics' DAF and DAFF installations offer the cumulative value engineering benefits and performance improvements obtained from numerous operating installations in Australia.

Daff plants incorporate highly efficient combined air/water wash dual media gravity filters with independent PVC under-drains and air scour laterals. Primary washwater distribution and media support gravels are stabilised with high SG garnet gravel.

Aquagenics is a CITECT accredited systems integrator with 35 Water Treatment SCADA installations. The degree of DAFF systems SCADA development and facility is advanced in terms of comprehensiveness and relevance in the operations context.