DAF Details

Dissolved Air Floatation (DAF) is a widely used clarification process. DAF removes particles from water using air bubbles that collide and attach to particles. The particle bubble aggregates are then separated once they rise to the surface of the tank

Application

It has applications in several fields which include

1. Drinking water, Municipal, ETP , STP and industrial wastewater, Hospital, Hotel & Restaurant Domestic Building insitu treatment of lakes for algae and sea waters for algae and oil spills
2. The most common method of producing air bubbles is the pressurized recycle flow method. In this method, a recycle flow of treated water is pumped to a saturator vessel where air is added under pressure and dissolved
3. The pressurized-recycle flow from the saturator is then introduced into the contact zone of the DAF tank. The pressure change across nozzles causes the dissolved air to come out of the solution in the for mof small air bubbles
4. In fluent from equalization tank is pumped to the DAF unit before flocculation. After DAF unit, the waste water goes to flocculator for further removal of TSS and then it moves to the aeration tank for pro peraeration.
5. LDAF was utilized in leachate treatment as a batch process and focused in colour and COD removal. Using DAF alone, 36 and 33 percent removal for COD and colour was obtained. Nevertheless, the removal increase up to 77 and 93 percent for COD and colour using coagulation process prior to DAF

1. DAF is more efficient in removing low-density floc then sedimentation processes
2. The problem of algae clogging filters and reducing filter run times usually occurs in the plants. But DAF is effective in removing algae from water supplies. In fact, air bubbles formed in DAF can also remove some taste and odor compounds from the water which can be consider as a secondary benefit DAF is more effective than sedimentation in removing pathogens such as Giardia cysts and Cryptosporidiumoocysts
3. DAF plants have a lesser footprint compared to sedimentation plants on account of smaller tanks. In some cases, DAFis placed over filtration reducing the plant footprint further
4. DAF produces floating sludge with higher percent of solids which possibly reduces sludge treatment and disposal.
5. Energy savings is higher in DAF compared to sedimentation plants as smaller motors are used to run the flocculator, longer filter runs, and less filter back washing of filter