What is the working principle of walnut shell filter material filter equipment

The treatment of oily sewage with filtration technology is a new development in the treatment of oily sewage, which is mainly used to separate finely dispersed emulsified oil that cannot naturally float through a degreasing tank. The filtration separation method of finely dispersed emulsified oil in water is also known as coalescence. This method uses the hydrophobic agglomeration of oil beads on the surface of the filter material and the formation of an oil film on the surface of the filter material, which is then washed away by the shear force of the water flow between the pores of the filter layer to form coarse oil beads floating and separating.
According to the principle of physical and chemical flotation kinetics, the agglomeration force (F) of the finely dispersed oil droplets in water on the filter media depends on the particle size (r) of the oil droplets in water and the interfacial tension between the oil and water phases. The relationship is as follows: F=4r. From this formula, it can be seen that the size (r) of the oil droplets in water is large, and the interfacial tension between the oil and water phases is large, which is beneficial to coarse graining. Increasing the content of inorganic salts in water can increase the interfacial tension.
The walnut shell filter is to use the above principle and the porous and large surface area of the specially treated wild walnut shell to intercept suspended solids and oil beads in the sewage on the surface of the filter material layer or adsorb on the surface of the filter material. When the filter material is saturated with effluent water quality deteriorates, stop the inflow of water for backwashing to restore the original characteristics of the filter material, and the backwash water will take away the retentate, and finally achieve the effect of filtering oil and mechanical impurities.