Dissolved Air Flotation System: Efficient and Durable Solution for Wastewater Pre-treatment
News 2024年11月15日 6
In the realm of wastewater pre-treatment, dissolved air flotation (DAF) stands out as a highly effective process that harnesses the principles of air dissolution and bubble-particle flotation. This method is meticulously designed to target and remove oils, greases, and fine particulates, ensuring that the effluent meets the highest quality standards.
The Pre-Treatment Phase: Coagulation and Flocculation
The journey of dissolved air flotation begins with a crucial pre-treatment phase. Here, chemical coagulants such as aluminum sulfate or ferric chloride are introduced to neutralize the charges of suspended particles in the wastewater. Following this, flocculants are added to bind these neutralized particles into larger clusters, known as flocs. These flocs are pivotal for the subsequent flotation process, as they enhance the interaction between particles and bubbles, thereby increasing the efficiency of the dissolved air flotation process.
Pressurization and Air Dissolution: The Heart of DAF
A key component of the dissolved air flotation system is the pressurization and air dissolution stage. A portion of the treated water is directed to a separate chamber where it is pressurized, and air is injected and dissolved under high pressure, typically ranging from 4 to 6 bar. This pressurized water, now saturated with dissolved air, forms a supersaturated solution, which is essential for the effectiveness of the dissolved air flotation process.
Pressure Release and Bubble Formation: The Lift to Clarity
Upon release into the main wastewater tank at atmospheric pressure, the air-saturated water undergoes a transformation. The reduction in pressure causes the dissolved air to form microbubbles, with diameters typically between 10 to 100 micrometers. These microbubbles are the lifting agents in the dissolved air flotation process, attaching to suspended solids and facilitating their ascent to the surface.
Bubble-Particle Interaction and Flotation: The Art of Separation
As the microbubbles rise through the wastewater, they interact with and attach to suspended particles, including oils, greases, and other low-density contaminants. The buoyant force generated by these bubbles causes the particle-bubble aggregates to float to the surface, forming a thick layer of floating sludge. This step is critical in the dissolved air flotation process, ensuring that even the finest particles, which are challenging to remove through sedimentation, are effectively separated.
Sludge Removal: The Final Act of Dissolved Air Flotation
Once the floating sludge layer has formed at the surface, it is mechanically skimmed off using scrapers or skimmers. The removed sludge, rich in concentrated contaminants, is collected for further treatment, such as dewatering or digestion, or disposed of in compliance with environmental regulations. This marks the culmination of the dissolved air flotation process, where the wastewater is significantly clarified.
Effluent Discharge: The Promise of Clean Water
Following the removal of the sludge, the clarified water at the bottom of the tank is discharged. Depending on the required water quality standards, this water may undergo further treatment or be released for direct use. The dissolved air flotation process ensures that the discharged water contains significantly lower levels of suspended solids, oils, and other contaminants, fulfilling the promise of delivering clean, usable water.