The working principle of a walnut shell filter is based on the coarse particle aggregation effect. Utilizing the hydrophobic interaction of floating oil, dispersed oil, and other oil droplets on the filter surface, the droplets gradually aggregate to form an oil film. As oily wastewater is continuously filtered, the fluid flow within the pores of the filter media generates shear force, washing away the oil film and forming floating and separated coarse oil droplets.

Product Detail

I. Product Introduction

When the oily wastewater flows through the porous, large-surface-area filter layer, finely dispersed emulsified oil and suspended solids are mechanically sieved and adsorbed within the filter layer.

As more and more suspended solids and oil are trapped on the surface, the trapping layer thickens, the pore size decreases, the surface filtration rate increases, the flow holes decrease, and the pressure difference in the filter layer increases. At this point, the filtration process must be stopped, and periodic stirring and backwashing must be performed. The filter media is stirred by a top agitator driving the paddles; through continuous stirring, solid impurities (such as dirty oil, inorganic salt deposits, and suspended solids) accumulated on the surface of the walnut shell filter media are thoroughly separated from the filter media.

After stirring, the backwashing process begins. By introducing qualified water from the bottom, pollutants from the top are discharged into the production water treatment process through the top sewage pipe, thus thoroughly cleaning the filter media and restoring its ability to retain pollutants. During the treatment of oily wastewater, the filter media continuously retains pollutants such as asphalt, oil, and inorganic salt scale. These pollutants continuously adhere to and accumulate on the surface of the filter media;

Fluctuations in upstream water quality and the long-term operation of the walnut shell filter can affect its filtration efficiency. Once the filter media is contaminated, it is difficult to restore its filtration function. When the contamination reaches a certain level, the filter will lose its filtering effect.

Walnut shell filter media is hydrophilic. The surface wettability of hydrophilic filter media with water greatly increases the contact area and action area between water and filter media. Water overcomes capillary forces and makes contact with the filter media easier. Asphalt, heavy oil, emulsified oil, and other high-viscosity, high-density components in oily wastewater easily clog the pore channels between the filter media and are difficult to remove effectively by backwashing, leading to filter media failure.

Therefore, the cleaning agent should be both hydrophilic and oleophilic, with an appropriate ratio of the two.

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