The effect of Dissolved air flotation separation is related to the size and number of bubbles. The ideal bubble size is 1530/m, and the air content in the water must be increased. As the impurity content in wastewater increases, the probability of contact and adhesion also increases. Therefore, the consumption of air per unit volume also decreases. The bubble size must be stabilized during the floating process. To this end, various foam generating agents are added to reduce the surface energy of phase separation. Such as adding rosin, cresol, phenol, sodium alkyl sulfate, etc. Some of the functional groups in these substances have properties such as trapping and foam generation. The weight of impurity particles in wastewater does not exceed the adhesion of particles to bubbles and the buoyancy of bubbles. The size of particles with good air buoyancy performance depends on the density of the material, which is about 0.21.5mm.