Dissolved air flotation (DAF) is a type of air flotation, which utilizes the different solubility characteristics of water under different pressures to pressurize and aerate all or part of the water to be treated (or after treatment) to increase the air of the water. The dissolved amount is introduced into the water with the coagulant added, and released under normal pressure, and the air is precipitated to form small bubbles, which adhere to the impurity flocs, causing the overall density of the flocs to be lower than that of water and rise, thereby separating solid and liquid.
Under high pressure, water is dissolved into a large amount of gas as a working medium (dissolved gas water), and the initial release system is suddenly decompressed and released, forming many fine bubbles (particle size of 20-40um), which adhere to the air after the initial coagulation reaction. On the "alum flower" in the wastewater, the specific gravity of the floc is less than that of the water, and then floats up to form a foam (a combination of gas, liquid and solid) on the liquid surface, which actively removes the pollutants in the water and reaches the function of clear water.
Dissolved Air Flotation (DAF) is suitable for treating water with low turbidity, high color, high organic content, low oil content, low surfactant content or with rich algae. Compared with other air flotation methods (see Appendix 1 for details), it has the advantages of high hydraulic load and compact tank body. However, its complex process, large power consumption, and high noise of the air compressor also limit its application.
1. When going to work, check whether the inlet sewage pump and return pump of the dissolved air flotation machine are frozen, including the lubrication and refueling of the water pump, the tightness of the packing, the sealing of the bottom valve, and the oil filling of the air compressor.
2. Check whether the air compressor air filter is frozen to determine whether the air compressor is running normally and whether there is noise and heat.
3. Check whether the transmission part and scraper of the slag scraper become hard and break in the cold state, so as not to affect the use.
4. Pay attention to the coagulant stirring storage tank to avoid freezing, and often do small sample tests.
5. Check the valve pipeline of each equipment to prevent the valve pipeline from being blocked, and place it in the "on" or "off" position as required.
6. When shutting down, the water must be drained to avoid freezing and clogging.
