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How does cloth filter work as a filter technology?

A cloth filter - also called bandpass filter or paper band filter - removes solid particles from the water by means of filter paper, applying a filter accuracy of approximately 15 to 50 microns. A cloth filter is used for the filtering of different water flows within glass horticulture companies, such as the drain water of ebb and flow systems, basin water, rinse water of sand filters and bypass filtration of a clean-water tank.
Joshua Reijnen
Technical specialist Water engineering | February 12, 2021 | 3 min. reading time

Filter principle

A cloth filter works according to a simple principle: when the water to be purified is guided across the filter paper, the dirt particles from the water that are larger than the pores in the filter paper, will remain. Here the following applies: the smaller the pores in the filter paper, the more pollution is filtered from the water. After a while, the pores will be ‘full’ and the cloth will be saturated. The cloth filter system will then automatically renew the filter papier. Since the contamination is discharged via the cloth, the cloth filter does not require any rinse water for cleaning.
Cloth filter

Choosing a cloth filter

When you want to use cloth filter as a filter technology, you can choose from different types of cloth filters. When choosing a cloth filter, three factors matter: the desired flow in m3, the contamination and the space available.

Desired flow

You can choose to apply the cloth filter either in full flow or in bypass. When a volume of water must be filtered briefly, it is preferred to buffer this volume and then treat it in batches. This is done, for example, with filter backwash water. The buffering could be done in a breaker tank that contains a process pump that pumps the water to be treated across the band filter.

Contamination

Depending on the contamination there are different types of filters that can be chosen from:
  • The flatbed filter is the most suitable in case of low contamination. The hydrostatic pressure of a flatbed filter is low.
  • The deep bed filter is suitable in case of average contamination. The filter makes use of an increased hydrostatic pressure relative to a flatbed filter, with the consequence that the deep bed filter is capable of retaining the flow rate in case of a higher contamination.
  • The hydrostatic filter has the highest hydrostatic pressure and is thus suitable for water with a high contamination level.
Flatbed filter
Fladbed filter
Deep bed filter
Deep bed filter
Hydrostatic filter
Hydrostatic filter
Apart from the choice for the type of cloth filter, also the correct filter paper must be chosen for a certain contamination. The choice of the papier depends on the desired filter fineness. the finer the filter accuracy, the closer to the paper. There are different types of filter paper. The filter accuracy varies from 50 to about 15 microns. The filtration is not absolute; during the filter process the accuracy will become finer up to the moment that the paper is saturated and the paper is refreshed (automatically).

Available space

Finally, the available space can be decisive for the choice of a certain type of cloth filter. If there is too little space, there may, for example, not be enough space for the buffering of the water. In this case full flow filtering would be the best choice; this take up less space because it doesn’t require the placing of an additional tank.

Check and maintenance of cloth filter

A cloth filter requires little maintenance. It is important though that you check the cloth filter (or have it checked) periodically on the functioning of the drive motor, float and drive rolls. Also the filter paper must be replaced sufficiently frequently.
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Can't find your answer? Fill out the contact form and our specialist Joshua Reijnen will get back to you. On weekdays, even within 24 hours.

How does cloth filter work as a filter technology?

A cloth filter - also called bandpass filter or paper band filter - removes solid particles from the water by means of filter paper, applying a filter accuracy of approximately 15 to 50 microns. A cloth filter is used for the filtering of different water flows within glass horticulture companies, such as the drain water of ebb and flow systems, basin water, rinse water of sand filters and bypass filtration of a clean-water tank.
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Joshua Reijnen
Joshua Reijnen
Technical specialist Water engineering | February 12, 2021 | 3 min. reading time
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Filter principle

A cloth filter works according to a simple principle: when the water to be purified is guided across the filter paper, the dirt particles from the water that are larger than the pores in the filter paper, will remain. Here the following applies: the smaller the pores in the filter paper, the more pollution is filtered from the water. After a while, the pores will be ‘full’ and the cloth will be saturated. The cloth filter system will then automatically renew the filter papier. Since the contamination is discharged via the cloth, the cloth filter does not require any rinse water for cleaning.
Cloth filter

Choosing a cloth filter

When you want to use cloth filter as a filter technology, you can choose from different types of cloth filters. When choosing a cloth filter, three factors matter: the desired flow in m3, the contamination and the space available.

Desired flow

You can choose to apply the cloth filter either in full flow or in bypass. When a volume of water must be filtered briefly, it is preferred to buffer this volume and then treat it in batches. This is done, for example, with filter backwash water. The buffering could be done in a breaker tank that contains a process pump that pumps the water to be treated across the band filter.

Contamination

Depending on the contamination there are different types of filters that can be chosen from:
  • The flatbed filter is the most suitable in case of low contamination. The hydrostatic pressure of a flatbed filter is low.
  • The deep bed filter is suitable in case of average contamination. The filter makes use of an increased hydrostatic pressure relative to a flatbed filter, with the consequence that the deep bed filter is capable of retaining the flow rate in case of a higher contamination.
  • The hydrostatic filter has the highest hydrostatic pressure and is thus suitable for water with a high contamination level.
Flatbed filter
Fladbed filter
Deep bed filter
Deep bed filter
Hydrostatic filter
Hydrostatic filter
Apart from the choice for the type of cloth filter, also the correct filter paper must be chosen for a certain contamination. The choice of the papier depends on the desired filter fineness. the finer the filter accuracy, the closer to the paper. There are different types of filter paper. The filter accuracy varies from 50 to about 15 microns. The filtration is not absolute; during the filter process the accuracy will become finer up to the moment that the paper is saturated and the paper is refreshed (automatically).

Available space

Finally, the available space can be decisive for the choice of a certain type of cloth filter. If there is too little space, there may, for example, not be enough space for the buffering of the water. In this case full flow filtering would be the best choice; this take up less space because it doesn’t require the placing of an additional tank.

Check and maintenance of cloth filter

A cloth filter requires little maintenance. It is important though that you check the cloth filter (or have it checked) periodically on the functioning of the drive motor, float and drive rolls. Also the filter paper must be replaced sufficiently frequently.
Contact form
Can't find your answer? Fill out the contact form and our specialist Joshua Reijnen will get back to you. On weekdays, even within 24 hours.
Joshua Reijnen
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