How do Sand Filters Work?

 As a solid-liquid separation device, Sand filters mainly treats water by physical filtration. The following is its detailed working process.

1. Filtration stage

Preliminary filtration: When water containing impurities enters the water inlet of the sand filter, it will first flow through a pretreatment area. This area may be filled with filter materials with larger particles, such as coarse gravel. These larger filter materials can intercept some relatively large suspended matter in the water and play a role in preliminary filtration.

Fine filtration: The water that has been initially filtered continues to flow downward and enters the filter layer composed of gravel of different particle sizes. These gravels are usually arranged in order of decreasing particle size from top to bottom, forming a gradient filtration structure. When water passes through the sand layer, smaller suspended matter, bacteria, some organic matter and other impurities will be intercepted by the surface of the gravel.

2. Impurity removal mechanism

Sieving effect: There are small pores between the sand grains in the gravel layer. When the impurities in the water are larger than these pores, they will be physically blocked on the surface of the sand grains and cannot pass through with the water, thereby achieving separation from the water.

Sedimentation and attachment: Some smaller particles of impurities may settle on the surface or pores of the gravel due to gravity in areas with slower water flow. At the same time, some impurities with charges may also adhere to the surface of the sand through electrostatic attraction and be removed.

The sand filter effectively removes impurities in the water through reasonable structural design and filtration process, ensuring water quality and providing reliable pretreatment for subsequent water use.

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Nina

Email: nina@filtrationchina.com

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