Complaint
DAF systems separate solids, oils, greases, and other impurities from water. The clean water can be reused or discharged. DAF is used for a variety of goals, including:
DAF uses micro air bubbles (30-50 micron) that attach to impurities and flocculated particles and float them to the water's surface. Then a skimming system removes the sludge to a desludging trough, and clean water is recovered.
The clean water can be reused for process or discharged, and some of it is recycled back to the DAF process.
First, clean water needs to be accessible for a DAF system to startup. Clean water is necessary because DAF systems pressurize the water and mix it with pressurized air. Under pressure, the air dissolves, and when de-pressured, micro-bubbles form. The micro-bubbles are necessary to the cleaning process.
So, the first step is to fill the DAF system with clean water. If you fill the DAF unit with wastewater, you'll likely discharge wastewater for a long time. Plus, you risk damaging the recirculation pump and air saturation system.
Once clean water is in the system, a recirculation pump pulls some of the clarified water to a pressurization-saturation system. Next, the water is pressurized by a pump and mixed with pressurized air. Under this pressure, the air dissolves in the water.
Now the saturated water flows under pressure to the clarification tank. In the clarification tank, the pressure releases, and micro-bubbles form.
The micro-bubbles attach to the impurities from the incoming wastewater stream and pull them to the top. When sediment rises, a floating sludge blanket forms on top of the water within the clarifier.
Finally, clean water is recovered through a supernatant system. Basically, the clean water comes out of a discharge point below the floating sludge and above the settled sludge.
Most systems account for and manage settled sludge. DAF systems are ideal for wastewater streams that contain solids that float and settle.
In general, you'll find most manufacturers include a sediment compartment or basin with a sludge extraction system
Coagulants and flocculants are regularly used to pretreat wastewater before it enters a DAF system.
Like other wastewater treatment methods, a DAF system can benefit from particles that bind due to flocculants. The skimming systems can remove a thicker, more dewatered sludge that may need little to no further dewatering.
