Multimedia water filters
Multi-media water filters or (multi-media filters) are a pressure filtering vessel with three or more different media on top of the gravel layer. Hard coal (anthracite), sand, and garnet are often chosen because of their different sizes and densities. Hard coal (anthracite) is the lightest, then sand, then garnet. The gravel is usually at the bottom as a support to keep small media out of the distribution system and to stop water being directed.
Filtration is the process of removing solids from a liquid by passing it through a porous medium. Coarse, medium and fine porous media are used according to requirements so that the physical composition of the filter media varies greatly according to the nature of the contaminants needed to be removed. This filter media thus prevents the passage of contaminants through physical obstructions, chemical adsorption, or a combination of both.
Multimedia sand filtration systems also known as depth filters or turbidity filters, usually used for commercial and industrial applications, are the most common type of water filter to date.
Why do we need multimedia filtration systems
The multimedia filter is used to reduce the level of turbidity and total suspended solids in the water to be treated. These suspended solids consist of small particles such as silt, clay, gravel, organic matter, algae and other microorganisms.
If multi-layered filters are not used as initial treatment, it can cause a high proportion of suspended solids, which leads to a pressure drop and reduced effectiveness of the rest of the water treatment equipment, filters, membranes, reverse osmosis membranes, EDI system, and UV sterilizers. Ultraviolet and ion exchange systems. Therefore pressure vessels containing sand or other bulk media are widely used to reduce the level of suspended solids (turbidity) in incoming water.
Work history with multimedia water filters
The use of water filters as a method of water purification began as early as 2000 BC in ancient Egypt. The filtration then evolved from the simple Hippocratic fabric housing to the complex solid carbon block and multi-media water filters currently on the market. Water purification using multimedia water filters is now the first and best way to purify water, removing more water pollutants more efficiently than any other technology.
Multimedia Filter Components
Filter tank: either stainless steel, FRP fiberglass or epoxy coated steel.
Filter layers: different layers of gravel, silica sand #20, gravel, hard coal
Upper and lower inner distributors: Either PVC 80 or stainless steel
Valves: electric or pneumatic automatic valves for automatic filters, or manual valves for manual filters.
PLC control: or digital control system
Interface tubes: PVC 80, stainless steel or epoxy-coated carbon iron
Flow Control: On the Wastewater Side
The difference between multimedia filter and sand filter
A typical sand filter is a single media filter, because gravel is a non-filtration layer. In a single media filter the smallest particles travel over several backwash cycles to the top of the media bed while the larger and heavier particles settle to the bottom of the filter. Most filterable particles are trapped in the source water at the top of 1-2 inches, as smaller media particles have the smallest spaces between them, and this is an inefficient use of media depth.
How to choose a multimedia filter
Choosing a multimedia filter depends on several different factors that must be considered in order to achieve good filtering results:
Maximum flow rate required
Nature of suspended solids or turbidity (colloidal or non-colloidal)
Analysis of the water to be treated
Required quality of treated water
Provides enough water for backwashing
What makes multimedia filters special?
It is easy to clean.
It is used to treat large amounts of pollution in water, as it is used when the value of the plankton density index is greater than 3, or when the turbidity is greater than 0.2 NTU, in order to prevent premature sedimentation on reverse osmosis membranes and microfiltration. All film manufacturers require plankton treatment to be less than 3, otherwise the warranty will not be valid.
Reduces the need to replace filter cartridges or bags, and reduces labor effort.
It has the ability to “backwash”. Backwashing is the purification and cleaning of the filter from the accumulated and filtered particles so that the filters’ high performance is restored.
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