What is a disc filter?
A disc filter is a type of water filter that was initially intended for irrigation water filtration, but over time have been used in industry for sediment retention applications.
It was an evolution of the basket or mesh filter, but in the case of the disc filter, the filter cartridge consists of several plastic discs stacked on top of each other.
How does a disc filter work?
Each disc has small grooves that when joined retain the unwanted sediments at their depth. Each of the discs (or rings) has a groove in the middle, forming a hollow channel in the center. Water passes through the small passages in the middle and impurities are trapped behind, as the slot closes.
How are disc filters classified?
The discs are color-coded to classify he level of filtration (Figure 1). Filtration quality is usually measured in microns. From 5 microns filtration for the finest level to 400 microns for the thickest. Usually a filtration average of 130 microns is used, for example for irrigation or surface water filtration. The degree of filtration is comparable to the mesh size we usually use in the industry. When using mesh sizes, 5 is the coarsest and 400 is ted finest or highest filtration level.
The quality of the filtration is measured by the quantity and size of the particles that the filter element is able to retain. This depends on the geometry of the channels, including the size, length, angle and number of intersection points generated.
What connection diameters does a disc filter have?
The disc filters depending on the size have an inlet and outlet of 3/4 ″, up to 2 ″, but the collectors can increase their diameter from 6 ″ to 12 ″ inches, used for drip irrigation systems in gardens, up to very benches. Large multiple grouped filters used to filter large volumes of water for agricultural and industrial applications (Figure 4).
How are disc filters cleaned?
Some disc filters, especially the small ones, need to be dismantled and cleaned manually.
For multi-filter systems, it is recommended that their washing or backwashing be automate, where the moment the water pressure increases due to retained dirt, the systems discs automatically decompress and change the water flow for the cleaning or backwashing cycle.
In some cases, a pump may be needed to do the washing or backwashing more efficiently or they may be air assisted to save even more water and do a faster backwash (places where water is scarce).
Disc filters can retain various types of sediment, including fine sand and undissolved organic matter. However, when used to filter out organic matter that settles, they can clog up more quickly than a multi-media filter and will need to be cleaned more often.
What are the advantages of using disc filters?
An advantage of this technology is that, they use less water than conventional deep-bed or multimedia filters, so in the medium to long term, the economic convenience in saving water and time between backwashes is greater. This makes it more convenient than multi-media granular filters.
Most common applications for water filtration with disc filters:
- Filtration for drip irrigation effluents.
- Surface water irrigation water filtration.
- Hydroponics systems.
- Industrial filtration.
- Filtration in water treatment plants.
- Pre-treatment of water softening or reverse osmosis systems.
- Water recirculation.
- Cooling towers (part of the filtering system).
- Replacement of sand, anthracite or zeolite filters in water treatment.