In industrial wastewater treatment, the flocculation (coagulation) process is one of the most widely used key links. Coagulation mixing methods include hydraulic mixing and stirring, mechanical mixing and stirring and compressed air mixing and stirring.
Compressed air stirring is the shear force generated by the compressed bubble in the rising process and the vortex formed by the density difference as the power of the coagulation reaction, and its advantages are: simple control, small operation and maintenance workload, good treatment effect, and can save chemicals. Pneumatic coagulation is better than mechanical coagulation, which is mainly reflected in the special mechanical stirring of air bubbles in water to form microcrystals of solid-phase hydrolysate products on the surface of bubbles. At present, most of the chemical phosphorus removal sewage treatment plants in foreign countries are located in the aeration tank, and the ideal phosphorus removal effect is achieved through air mixing and coagulation reaction. A large number of water treatment literatures have reported that the pneumatic coagulation stirring process is better than the mechanical stirring coagulation effect when applied to the treatment of tannery wastewater, printing and dyeing wastewater, and high nitrogen and phosphorus wastewater.