What are the processes of walnut shell filter decontamination

The dirt interception process of walnut shell filter media and the nature of dirt interception mainly include the following aspects:

(1) The sedimentation fouling formed by the suspended particles deposited on the surface of the filter material under the action of gravity: the denser suspended impurities in the oil production wastewater are continuously deposited on the surface of the filter material under the action of gravity, and the resulting dirt is on the surface of the filter material. The adhesion on the surface is very weak and it is easy to remove from the surface of the filter material. The main thing that is removed by the hydraulic backwash method is this kind of dirt.

(2) The dirt attached to the surface of the filter material under the effect of physical adsorption or adhesion on the surface of the filter material: This type of dirt is mainly oily, and due to its hydrophobicity, it is easy to adhere to the surface of the filter material particles. In the walnut shell filter , The oil particles adhere to the fine suspended particles, and adsorb on the surface of the filter material to form dirt.This form of attached dirt is often difficult to remove by hydraulic cleaning due to its hydrophobicity.

(3) The dirt attached to the surface of the filter material under the action of electrostatic gravity: When the suspended particles in the waste water and the surface of the filter material have opposite charges, it will be adsorbed to the surface of the filter material under the action of electrostatic gravity; the negatively charged dirt particles and The surface of the same negatively charged filter material can also condense on the surface of the filter material under the action of the high concentration of positively charged metal cations to form dirt. Under the condition of hydraulic recoil, this type of dirt depends on the strength of its interaction with the surface of the filter material or The bonding strength can be removed to a certain extent.

(4) Diffusion that penetrates into the internal pores of the filter material under the effect of diffusion: The walnut shell filter material has a certain pore structure. Due to the diffusion effect, the pollutants and impurities in the water will migrate to the inside of the filter material pores. It can be found from the scanning results of the electron microscope. After the material is intercepted, the original pores are obviously blocked. If only by hydraulic cleaning, the dirt in the pores cannot be removed, and the walnut shell filter material cannot be restored due to its porous properties, which will result in a reduction in the interception capacity. After cleaning with chemicals, both the surface of the filter material and the pores of the filter material can basically be restored to the state before the interception.