Clean water pouring after filtering through glass filter media

Activated Glass Filter Media - Acti Desolidex, Uses, Sizes and Benefits

As part of a wide bouquet of water treatment solutions, Acti Desolidex is available from African Pegmatite and offers some of the highest performance characteristics in water purification around.

The world wants, and indeed the world needs clean, filtered water. Many are unaware of the need for filtration as part of a water cleaning programme, let alone what technologies are used and just how effective it can be. Filtration is a simple idea and remains one of the most effective methods to clean up water.

Filtration technologies, however, have become highly developed in modern times, with capacity for high throughput and long system running times allowing greater access to cleaner water for millions of people. It isn’t just people, however, many industrial processes require a clean supply of water. Processes like in-line filtration with glass or sand filter media, or with specialist products such as Acti Desolidex provide highly stable and low cost solutions to industrial water requirements. The risk of not filtering water in advance of providing a drinking water supply or ahead of an industrial process can have serious ramifications. Therefore, it is essential to employ a robust, effective and reliable filtration operation.

Activated Glass Filter Media

Activated glass filter media is a broad term for a whole host of ground glass technologies that when placed into a filter basket in an in-line filter system, will provide good to excellent filtration characteristics. These ground glass substrates are interchangeable with traditional or conventional sand and/or silica filters, whilst remaining as cost effective and high performing.

What is activated glass filter media?

In large water filtration systems, it is a modern replacement for traditional sand media. The use of a particular type of glass is activated; it offers an increase in its surface area and is negatively charged to attract and extract both heavy metal compounds and organic residues from water in order to purify it.

Activated filter media is a more modern and better replacement for the old sand methods. Depending on installation and inbound water quality, the use of activated glass can double the performance and effectiveness dramatically over older systems for high output water purification. Whilst glass filtration is more effective than sand and silica, activated glass filtering is even more effective again.

Why Not Continue to Use Sand or Silica?

Modern glass and activated glass filters are significantly more resistant to biofouling, bio-coagulation and even transient wormhole channeling than sand or silica of any unfiltered water. Glass/activated glass filters do not require recharging or replacing for many many years.

African Pegmatite uses a specific glass type which has been taken from recycled glass and processed down to specific and optimised particle sizes and shapes (see below). This optimised glass is then put through a number of processes designed to negatively ‘activate’ the glass - thereby increasing its surface area by around 300 times normal amount whilst providing a small negative charge at the surface. This vastly improves its mechanical and electrostatic filtration performance.

Furthermore, the resulting activated surface is known to be self-sterilising. Which means bacteria and other impurities cannot attach themselves to the surface of the glass, but do not pass through the filter. Regeneration is simply applied by backwashing with water to restore glass particles to their initial state, as part of a standard process maintenance regime. Backwashing will dislodge undesirable particulates from the filter allowing for their disposal. This is possible because activated glass is not the same as standard glass media due to the aforementioned treatment.

waste water/treament facilty that could use acti-desolidex

Activated Glass Filter Media vs Other Glass Media

The activation process itself is the main aspect that sets active glass media apart from standard glass media. Activation produces its bio-resistance and it's highly efficient filtering capabilities. In terms of raw materials, African Pegmatite uses only green and brown recycled glass, sourced nearby to minimise carbon emissions and volumes sent to local landfill. The metal oxides that are in the glass and give the colour are the reason for the negative charge. This charge is increased during the activation.

Activated glass production is superior to glass filtration because it’s not simply recycled glass used in the process of filtration, it’s precision cut activated glass that can optimise any filtration system.

Who Uses activated glass filter media?

There are a number of industries who have now replaced normal filter media with that of this material for reasons of economy, efficiency and process robustness.

Application Materials extracted
Municipal wastewater systems Phosphorous, bacteria, BOD, COD and TOC
Industrial process water Organic pollutants, oils, TSS, VSS and particles of smaller than 1 μm
Industrial wastewater Colours, fibres, residual mineral oils, organic residues
Drinking water processes Heavy metals including iron, manganese, arsenic plus other dissolved, especially organic, chemicals

Activated glass filter media can be deployed in many situations, as testament to its versatility, such as:

  • Water filter treatments currently using Sand or Other filtration media
  • All naturally filtered pools
  • All filtered saltwater pools
  • Any process using oxidation method
  • Any process where the temperature is a factor
  • Underbedding or other particle size use

Acti Desolidex: A Superior Glass Media Filter

Acti Desolidex is a glass media filter suitable for in-line water purification applications, available exclusively from African Pegmatite. Derived from carefully processed, milled and treated recycled glass, every single particle in Acti Desolidex is optimsed through the manufacturing process to produce the very best material available, providing the best suited shape and size for the desired application.

Through the highly quality controlled manufacturing process, particle sizes and shapes are tailored to reduce sharp edges - not only to reduce potential damage to equipment, but to make backwashing easier. Acti Desolidex’s low bulk density of 1.3 g mL-1 means that up to 20% less needs to be used compared to traditional sand or silica filters. Its wide pH tolerance means it can operate in the range of 3 to 13, meaning it will be effective on all but the most strongly acidic and strongly basic liquid sources. It boasts a strong performance on flocculated suspended solids on both single and multi pass filtration pathways.

Acti Desolidex has a number of benefits over and above traditional sand filtration methods, and should be considered as a useful replacement.

droplet hitting water cleaned with acti-dsolidex

Benefits of activated glass filter media (Acti Desolidex)

  • Filters at least 50% better than the traditional sand method
  • Vastly reduced risk of parasites like Legionella, Pseudomonas, and Cryptosporidium
  • A sustainable product, produced from locally sourced recycled materials
  • Filtration at 100% efficiency without filtration aids
  • Drying furnace treated prior to activation
  • Targets efficient removal of organics, or inorganics, oxides, and other metals and minerals
  • Maintains optimum performance for many many years - more than four times the life cycle of sand
  • Both macro- and micro-sized pores enable Acti Desolidex to trap all particles
  • Backwashing frequency is reduced by an impressive 40% on average
  • The finest pore sizes enable filtering down to the macron scale for even cleaner water results
  • Materials are easily released with standard backwashing
  • Filtration times are reduced by an average of 25%
  • Eliminates algae growth
  • Lasts more than three times longer than sand or silica solutions
  • Chlorine use is reduced by an average of 40%
  • Running costs produce huge savings at one third that of the running costs for sand

Given this comprehensive list of excellent benefits over traditional methods, many quality sensitive water filtration companies and authorities are turning to new methods like the Acti Desolidex product for better, more efficient water filtration.

Size Availability of Acti Desolidex

Acti Desolidex is available in the following standard sizes, custom sizes are available on request.
● 0.4-1.0mm
● 0-1mm
● 1-3mm

Does Acti Desolidex require a change to current installations or equipment?

One of Acti Desolidex’s major advantages is that in the vast majority of cases, it can be simply swapped for the current filtration medium requiring no modification to filter housings or other operational changes. This is also the case for all activated glass filtration products available through African Pegmatite.

water treatment plant where acti-desolidex or anthracite could be used


Flow rates of between 8 and 12 cubic metres per square metre per hour at a pressure of between 100 and 120 kPa are the standard range for Acti Desolidex, with a backwash rate at the same pressure of 6 to 10 m3 m-2 h-1. Operational bed depths are typically in the region of 600 to 800 mm when a suitable nozzle arrangement is used, with large aperture nozzles able to be used with the application of between 100 and 500 mm of extra bed depth for Acti Desolidex. Based upon extensive laboratory testing, performance data for Acti Desolidex is as follows for flocculated pool water, across up to three passes, and for water in other conditions, as follows:

Flocculated pool water condition Single pass (%) Double pass (%) Triple pass (%)
92 NTU Turbidity 88 95 98
87mg L-1 total suspended solids 85 94 98


Water condition Single pass (%)
Organic suspended solids from biological treatments (i.e. COD removal) at 20 and 10 m h-1 velocities respectively 91, 98
TSS inorganic removal 82
Inorganic removal at 11 m3 m-2 h-1 at 100 kPa 81

Is Acti Desolidex Better Than Desolidex?

Desolidex and Acti Desolidex are highly related products and achieve similar outputs across a range of filtration activities. In general, regular Desolidex is more than sufficient for most filtration needs. Whilst Desolidex and Acti Desolidex both boast impressive filtration capacity, Acti Desolidex is produced to a larger particle size and is therefore better suited to less fine filtration, such as industrial solids removal instead of the production of medical grade water/saline. Acti Desolidex can, however, operate comfortably at a higher backwashing rate than can Desolidex. The decision over which to use depends on a multitude of factors including, but not limited to, the condition of the untreated water, the desired filter outcome and economic factors. Acti Desolidex shares Desolidex’s annual attrition rate of 5 to 6%, making it equally suitable for long term applications. Furthermore, African Pegmatite source 100% recycled and local glass material for Acti Desolidex production, meaning it has a minimal carbon footprint before reaching the operation site.


  • Acti Desolidex is an advanced activated glass media filter for high performance water filtration operations
  • Activated glass filters outperform traditional sand and/or silica based filters, providing better filtration over a longer lifetime and often at enhanced operation rates. Because of a lower bulk density, less glass filter medium has to be used compared to the equivalent for sand or silica
  • Such filters rely on highly optimised grind sizes and an overall negative surface charge - making removal of heavy metals from liquids, for example, easier
  • Glass filters and Acti Desolidex are environmentally friendly as they are produced from recycled glass waste
  • The efficiencies generated in backwashing with Acti Desolidex are realised with 75 to 80% water savings for each backwash cycle - as a result of smooth particle shapes
  • Acti Desolidex can be installed in pre-existing filtration setups without the need for extensive or expensive modifications


With a global distribution network providing the broadest reach and a wide bouquet of glass based water purification systems, African Pegmatite is best placed to supply high quality filter media - including Acti Desolidex - for any project size, for the most demanding and mission critical water purification applications.

acti-desolidex and other filter media displayed in pots