What Is a Media Filter and How to Choose It? | A 2024 Guide to Media Filters 

1. Introduction

Did you know that particles like sand, silt, leaves, and other impurities can disrupt water filtration, including processes like reverse osmosis? That’s where media filters come in! Whether it’s water pollution in irrigation, industrial cooling, small aquariums, or large pools, media filters efficiently remove suspended solids. The choice of material in these filters depends on filtration needs, location, particle sizes, and efficiency.

Curious about how media filters work and choosing the right one? Don’t worry! This guide explains the principles, types, applications, and significance of media filters in commercial and industrial settings.

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2. What Is a Media Filter?

A media filter is a type of water filtration equipment that is used to trap and remove all the suspended solids such as slit, clay, grit, organic matter, and algae from the raw water. The media filters can consist of one or more layers. Usually, a multimedia filter has four main layers, i.e., coal, sand, and garnet, with a supporting layer of gravel at the bottom. 

What Is a Media Filter (1)

  • Role of Media Filters in Water Treatment

You might wonder why we need a media filter if we have advanced filtration techniques such as reverse osmosis membrane filtration! The answer is that large impurities and suspended solids can reduce the water pressure needed for effective RO production and choke the RO membrane pores. This situation can lead to membrane fouling and increase maintenance costs. 

Media Filter process (1)

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3. How Does Media Filter Work/Media Filtration Water Treatment Process

The filtration process through the media filters will work by flowing the water through the three main layers of coal, sand, and garnet and the last (non-filtering) supporting layer of gravel. All these layers will trap particulates or suspended solids, and the filtered water will pass through. 

The topmost coal layer provides uniform water distribution throughout the filter media, while that of sand and garnet effectively removes the particulates. The porous structure of the first three layers of media filters can effectively reduce water contaminants without affecting the efficient water flow. By removing all the suspended solids, filter media ensures that the water quality meets water consumption standards.  

The last layer of gravel will physically support the above three layers of filter media. It provides support, ensures even water flow distribution, and prevents channeling. 

Media Filtration Water Treatment Process (1)

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4. What Substances Can the Device Remove?

A multimedia filter can reduce the SDI (Slit Density Index) and TSS (Total Dissolved Solids) from the feed water. In simple words, it can reduce the suspended solids and make the water clean and fresh for further use. 

An effective media filter is said to remove the particulates of sizes down to 15-20 microns. It can remove all the large-sized particles, such as leaves, rocks, and even small-sized particles, such as a slit, clay, garnet, algae, and even some microorganisms, depending on the layering approach followed in the multimedia filters. 

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5. What Are the Filter Media for Filters?

A media filter can consist of one, two, or more layers. Depending on the degree of water contamination and efficiency of filtration required, you can choose among the following types:

  • Single Media Filter: It is the simplest type of media filter with one layer of either sand or coal.
  • Dual Media Filter: These filters contain two layers, usually sand and coal. 
  • Multimedia Filter: These types of filters can have more than two layers. It can be coal, sand, garnet, and gravel. 

In multimedia filters, there is also an extra garnet layer between the above layers and the bottom gravel layer. This prevents the fine particles from entering the gravel layer and then exiting the filter. Moreover, the gravel layer supports all the above layers and prevents water channeling. Generally, the pore size of the layers will decrease from top to bottom. 

Filter Media for Filters (1)

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6. How To Choose Multimedia Filter?

There are various factors to consider when choosing a multimedia filter; each one plays a crucial role in the quality of filtered water we get. Let’s find out how to select a multimedia filter:

  • Understand the Water Quality:

The first thing to consider is the water quality on the premises. Identify the contaminants and ensure you choose the right multimedia filter type. If the contaminants are large-sized, only the Anthracite and gravel layer is enough, while the small contaminants would also require the garnet and sand layer. 

  • Filter Media Types:

Multimedia filters have three types based on media layers, i.e., single media, dual media, and multimedia filters. The common media types are sand, gravel, Anthracite, and garnet. The topmost layer of Anthracite can filter out the larger particulates, such as leaves or rocks, from the raw water. At the same time, sand and garnet are used to filter out the smaller particles, such as algae and microorganisms. 

  • Micron Rating:

A multimedia filter can remove the contaminants from water down to the size of 20 microns, while the ones with coagulant can filter out 10 microns or even less. Check the micron rating of the multimedia filter before buying for effective filtration.  

  • Backwashing:

Ensure that the multimedia filters you’re buying have a functional backwashing sequence, as it helps to rejuvenate the filter media and remove the contaminants. Backwashing involves the backward flow of water and sometimes the scouring of air to remove the trapped pollutants in the filter. The air can expand the layers while water can sweep out the trapped pollutants.

water filter Backwashing (1)

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7. Advantages of Multimedia Filters

Multimedia filters have many advantages in a water treatment plant, offering versatile filtration and ease of usage. Here are a few more:

  • Environmental friendly

    Multimedia filters can effectively remove various harmful impurities from water, helping to reduce negative impacts on the environment while protecting water resources.

  • Effectively remove contaminants

    Media filters are designed to remove both particles (usually large-size) and small-size particles from water. A layered approach that contains gravel, garnet, and sand in each layer effectively removes particles of different sizes.

  • Extend membrane system life

    As a pretreatment system for membrane treatment systems, this system can effectively filter out large particles and suspended solid particles to reduce wear on membrane accessories and extend their life.

  • Customizability

    Multimedia filters can be customized according to layers. This flexibility allows for the use of versatile and customized filtration systems adapted to different filtration requirements according to water quality standards.

  • Longer running time

    Multimedia filters can run longer before requiring maintenance. Since it is made up of multiple layers, each layer takes a while to reach its limit of capturing contaminants.

  • Improve water quality

    Multimedia filters improve water purity and remove odors, colors, and particles from raw water, thereby improving the quality of water received by the end user.

  • Wide applicability

    Suitable for reverse osmosis system pretreatment, industrial wastewater treatment, agricultural irrigation, food and beverage processing plants, swimming pools municipal water systems, etc.

Pressure Sand Filter Applications

  • Low maintenance cost

    Multimedia filters generally require low and relatively simple maintenance costs, reducing operating costs.

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8. Media Filter vs Regular Filter

Compared to regular or traditional filters, media filters can consist of more than a single layer (multimedia filter) and trap diverse particles in each layer. Hence, a multimedia filter will require less maintenance as the limit of trapping contaminants will be reached after a longer run. 

A multimedia filter is considered more versatile and efficient in particle removal than a regular filter. The media filters can be customized (with different layers) to target specific contaminants. 

Another difference is the size of contaminants that a filter can remove. A regular filter can have a micron rating of 50 microns, while a media filter can remove a particle down to the size of 10-15 microns.  

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9. Types of Multimedia Filters and Their Applications 

There are different multimedia filters, each with a specific layering approach, contaminants removal capability, micron rating, and applications. Following are the types of multimedia filters & their applications:

  • Sand media filter

Using sand as the main filter media is suitable for removing larger particles of impurities, such as sand, soil, and suspended solids.

  • Carbon Media Filter

Utilizes activated carbon as the filter media to effectively remove organic matter, chlorine, and odors for drinking water and water treatment applications.

Carbon Sand Filter

  • Ceramic Media Filter

A filter made from ceramic material. This filter is suitable for various commercial or industrial situations that require high-purity water.

  • Glass fiber media filter

Using anti-corrosion and durable glass fiber as the main filter media, it is suitable for high-efficiency filtration and removal of tiny particles.

  • Ultrafiltration Membrane Filter

Uses microporous membranes for filtration, is suitable for removing microorganisms, bacteria, and viruses, and is commonly used in drinking water and water treatment.

  • Sand & Gravel Mixed Bed Filter: 

These are dual media filters with two layers, sand and gravel. 

These multimedia filters can filter out the larger particles from water, such as sediment and silt, and can be commonly used in drinking water treatment plants. 

  • Anthracite, Sand, and Garnet Multimedia Filters 

This is a multimedia filter containing three layers. It reduces the sedimentation and turbidity of water while removing small and large particles and can be used in power plants. 

Sand & Gravel Multimedia Filters (1)

  • Sand, Anthracite, and Activated Carbon Multimedia Filter

This is a multimedia filter containing three layers. Different types of filter media are mixed to provide multi-level filtering effects.

It effectively removes sedimentation and organic matter from the water. Moreover, it reduces the smell by removing the chlorine as well. It is mostly used in the manufacturing industry. 

  • Zeolite Multimedia Filters:

These are the types of multimedia filters that utilize the zeolite alongside other layers. It is used where there is a need for ion exchange and removal of ammonia and heavy metals. 

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10. Conclusion

Do you know that even in 2023,  over 2.2 billion people still use poorly managed water services, causing tons of waterborne diseases, according to the World Health Organization? That’s where the need for Multimedia filters comes in! If you’re looking for exemplary service for water filtration systems, NEWater offers the best one in the market. 

NEWater has the carbon sand filter, quartz sand filter, multimedia sediment filter, multimedia sand filter, multimedia filter tank, industrial multimedia filters, and more solutions for your commercial and industrial needs. Contact the NEWater engineers and send queries for customized multimedia filters for the desired water quality. 

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