Quartz sand filters are generally used as pretreatment for reverse osmosis and ultrafiltration equipment, mainly for the retention and adsorption of silt, colloids, metal ions and organic matter. Common filter materials include quartz sand, activated carbon, anthracite, manganese sand, etc. It is widely applied in various industries such as agricultural irrigation, chemical engineering, petroleum, metallurgy, and mining. Now let's talk about when quartz sand filters need to be cleaned and backwashed?

Firstly, the cleaning and backwashing of quartz sand filters are for different operational purposes. Cleaning is an action carried out when the efficiency of backwashing declines. Backwashing is to remove the pollutants captured in the filter, ensuring that the filter's filtration function can continue to operate. The following is an introduction to the differences between the two.

Backwashing

The operation timing of backwashing for quartz sand filters is mainly determined by the decrease in the flow rate of the circulating pipeline per unit time to judge the efficiency of the filter. In practice, it is more often judged by the increase in the pressure of the filter, that is, the so-called pressure difference or head loss. This is because during the circulation and filtration of the pool water, pollutant particles are accumulated and collected in the quartz sand filter layer, causing the surface of the quartz sand particles to thicken, which in turn hinders the flow of water and increases the pressure of the filter. At this point, backwashing is needed to remove the accumulated pollutant particles, reduce the pressure of the filter and increase the filtration flow rate.

If the filtration system belongs to the circulating filtration type, it not only needs to take into account the condition of filtration efficiency, but also the ability to promote the circulation of water flow. Therefore, the control of head loss is generally recommended to be maintained at0.5kg/cmLeft and right, that is to say, beyond this pressure difference range, although the filtered water quality is relatively good, the filtered water output will decrease, and the thrust will also be insufficient, resulting in poor circulation efficiency and easy dead corners. The water quality will not improve due to filtration at this time; instead, it will get worse and worse. However, below this pressure difference range, although the number of water cycles increases and the thrust is sufficient, the filtered water quality is not very ideal. Moreover, backwashing too frequently will lead to the waste of water resources. Therefore, the filtration pressure after backwashing(Initial pressure)Plus0.5kg/cm2 (Pressure difference) It is the pressure required for backwashing(Final pressure)That is, the initial pressure is added0.5kg/cm2It is the pressure required for backwashing.

"Clean"

The reason why quartz sand filters need to be cleaned is the accumulation of grease rather than the calcification of the sand layer. As water contains a lot of suspended lipids, if these fatty substances are not properly impacted, they will accumulate on the surface of quartz sand particles, causing the quartz sand to rerepel the fatty substances. As a result, the fatty substances will continue to penetrate deeper into the filter layer and eventually fill the entire filter layer. At this point, Fatty substances cannot be captured by the filter due to the overall rejection of the filter layer, resulting in a slightly white, greenish and yellowish turbidity in the water. Even backwashing cannot improve the water quality, and the problem can only be solved by changing the water or replacing the filter material. However, this situation recurred not long after, and such conditions are particularly easy to detect in high-temperature pools. The commercially available filter cleaning agents are specifically designed for this situation. They are used to clean the organic lipids adhering to the surface of the filter material.

The filter needs to be cleaned when the following situations occur:

1The backwashing frequency of the filter is frequent, and the effective operation period is shortened.

2The initial pressure of the filter cannot be reduced after routine backwashing.

The above isAll the content about when quartz sand filters need to be cleaned and backwashed. If you have any questions about filter selection and operation, please consult Beijing Yuanlai Water Treatment Equipment Co., LTD.15With years of focus on the water treatment industry, you can trust us!