User Manual and Operating Procedures for DAF Machine

1. Working Principle

Dissolved Air Flotation (DAF) is a method that uses tiny bubbles as carriers to remove impurities from water. Sometimes, coagulants or flotation agents are added (depending on the water quality) to help the impurities adhere to the bubbles. This process makes the impurities less dense than water, allowing them to rise to the surface for separation and removal. The DAF process includes continuous steps of bubble generation, bubble-particle attachment, and flotation separation.

Two essential conditions are necessary for effective DAF separation:

1) Sufficient quantities of fine bubbles must be provided in the water, with an ideal bubble size of 15-30 μm.

2) The target impurities must be in a suspended or hydrophobic state to effectively attach to the bubbles and float to the surface.

The efficiency of the DAF process can be influenced by several factors:

1) Microbubble Size: This is determined by the method of air dissolution and the design of the release mechanism. Optimal bubble size is crucial for effective flotation.

2) Air-to-Solid Ratio: This ratio depends on the amount of air released into the water. Proper adjustment ensures that sufficient air is available to attach to the suspended solids.

3) Influent Concentration, Operating Pressure, and Flotation Time: The concentration of contaminants in the incoming water, the pressure at which the system operates, and the duration of the flotation process all play significant roles in the overall efficiency.

4) Effect of Chemicals: The use of coagulants and other chemicals can enhance the attachment of impurities to the bubbles, improving the flotation process. The type and dosage of chemicals must be optimized based on the specific water quality and contaminants.

2. Pre-Operation Checks：

1) Check All Valves: Ensure that all valves are in their normal working positions.

2) Check the Water Level in the Saturation Tank: Verify that the water level in the saturation tank is at the correct operating level

3) Check the Pressure in the Pressure Stabilization Tank: Confirm that the pressure in the pressure stabilization tank is within the normal operating range.

4) Check Electrical Equipment: Ensure that all electrical equipment is functioning properly and is in normal working condition.

3. Startup Procedures

1) Prepare and Add Coagulant: Prepare the coagulant solution and start the mixing system.

2) Start the Air Compressor: Open the intake valve and adjust the intake pressure to 0.2 MPa.

3) Start the Feed Water Pump: Supply water to the saturation tank and adjust the water level to approximately one-third of the saturation tank's level gauge. The pressure in the saturation tank should reach 0.4 MPa.

4) Adjust Chemical Dosage and Flow Rates: Based on the changes in effluent water quality, adjust the dosage of chemicals, the influent water volume, and the amount of water in the saturation tank to ensure optimal effluent water quality.

5) Control Sludge Discharge: Based on the amount of generated scum, control the effluent gate, adjust the scum level to meet the requirements of the sludge scraper, and start the scraper to remove the scum.

6) Check Inlet and Outlet Water Systems: After startup, check the balance between the inlet and outlet water systems to ensure the DAF system is functioning properly.

4. Shutdown Procedures

   1) Turn Off the Scraper

   2) Turn Off the DAF Inlet Pump

   3) Turn Off the Chemical Dosing Pump

   4) Turn Off the Air Compressor

   5) Turn Off the Cavitation Air Flotation Machine

   6) Turn Off the Cavitation Air Flotation Machine

5. Precautions

1) Once the water level in the saturation tank is adjusted, it should be maintained consistently and not frequently altered.

2) Adjust the chemical dosage, influent water volume, and saturation tank water volume promptly according to the changes in effluent water quality.

3) Apply grease to all bearings, chains, sprockets, gears, racks, and slides regularly (approximately every ten days) and conduct a thorough inspection every three months.