The Saint-Gobain Weber is the leading premix and exclay producer and provider of premix plants and machinery in Europe with more than 100 plants in some 30 countries. 10.000 employees contribute to an annual turnover exceeding about 2 billion EUR. The Saint-Gobain Weber manufactures lightweight aggregates that are sold as finished products or are used to manufacture blocks and assembly units. Lightweight aggregates products are used as filling material for road projects, other geotechnical purposes, insulation, building blocks and chimneys, and also for water purification.

Company details

PO Box 216 , Alnabru , Oslo NO-0614 Norway

Locations Served

Business Type:
Industry Type:
Water and Wastewater - Water Filtration and Separation
Market Focus:
Globally (various continents)
Year Founded:


Filtralite is the registered trade mark for all expanded clay products used as filter media that are manufactured by Saint-Gobain Byggevarer AS in Norway. Filtralite materials are crushed ceramic particles or round grains with a dense shell surrounding a porous core. The chemical and physical composition gives the grains properties used for many purposes, including filter materials.

Filtralite filter media are used for a number of water treatment applications; such as drinking water treatment, wastewater treatment and on-site treatment of effluent water.

Water is a necessity for all life
Drinking water is our most important resouce and water quality requirements are, and should be, very strict.

To achieve good quality drinking water, different types of treatments are used based on the quality of the the raw water. For many treatment processes Filtralite is an excellent filter media.

Research and Development
The development of Filtralite filter media is carried out in close cooperation with universities and research institutes both in Norway and worldwide. A doctoral thesis on drinking water filtration using Filtralite is completed. Many reports and papers have been written on various aspects of the use of Filtralite for drinking water treatment. Saint-Gobain operates a sophisticated laboratory for filter media testing, and cooperates with both Norwegian and international research laboratories.

Pilot plants
Running a pilot plant is usually the best way of achieving information on the performance of a specific process or a material used for water treatment.

Filtralite filter media is made by the burning of clay at about 1200º C, followed by crushing and sieving of the resulting expanded, clay pellets. The material has a very porous structure, and crushing exposes a large surface area. Dry particle densities are in the range 500-1,600 kg/m³, and the aggregate size range is 0-20 mm. Filtralite materials are flexible and can be 'tailor-made' for specific applications. The aggregates do not release any harmful substances and the acid solubility is minimal. Despite its low density and high porosity, Filtralite has high abrasion and impact resistance.

Three main types of Filtralite are available, with three different densities. For drinking water applications crushed material is used. The crushing have produced angular grains and allows full exposure of the porous core to the water.

Weber in Norway is a part of the international Saint-Gobain Weber company, again a part ofSaint-Gobain. Saint-Gobain is the world leader in the habitat and construction markets, designs, manufactures and distributes building materials, providing innovative solutions to meet growing demand in emerging economies, for energyefficiency and for environmental protection.

Weber specialises in the manufacture of high quality expanded clay and premix products, and is one of the largest expanded clay manufacturers in the world. In addition to building sector activities, Weber develops, manufactures and sells filter media to be used for different types of water and wastewater treatment processes as well as odour treatment.


Filtralite is certified for use in drinking water applications in accordance with the European Norm EN 12905. Weber's quality and environmental control system is certified according to ISO 9001 and 14001.


As an international company, Saint-Gobain take responsibility for our nature that provides us with the materials we use to create Filtralite. Clearly defined environmental principles define the long-term success of any company.

Emissions are a high-priority environmental factor
Future energy consumption is another important issue, as production of light weight expanded clay aggregates require a great deal of energy. ISO 14001 is implemented in the entire organisation of Saint-Gobain in Norway, where Filtralite is produced. By working systematically with ISO 14001, measurable environmental targets can be established and evaluated.

Saint-Gobain in Norway is certified both on quality, environment and for production of material for use in drinking water treatment:

  • Requirements: NSF International/ANSI 61
  • Quality: ISO 9001
  • Environment: ISO 14001
  • Products for use in treatment of drinking water: EN 12905

Transport & Delivery
Saint-Gobain has a lot of experience with transporting and delivering Filtralite to almost all parts of the world. Delivery method varies from project to project, subject to the customers need and the type of media. Most types of material qualities can be delivered in bulk or in big bags, with road- or sea transport.

Reduction of transport-emissions are high-priority
All types of Filtralite can be delivered in bulk. Bulk deliveries can be made to all parts of the world, either as road transport with trucks, or as sea- or river transport with vessels. By using tank trucks with blowing equipment, the Filtralite materials can be pneumatically discharged directly into the filters. Filtralite P, Filtralite NC 0,8-1,6 mm and Filtralite NC 1,5-2,5 mm are not recommended for pneumatical discharge.

Delivery in big bags
Delivery in big bags can be done for all applications and all Filtralite qualities. Big bags that are open at the top will normally be used. Most of the materials are normally delivered in 1,5 m3 big-bags. For deliveries to on-site wastewater treatment systems, the material is delivered in 1,0 m3 big bags. The big bags can be transported on trucks, trains or vessels, or they can be stuffed into containers. Transport in containers is a good solution for smaller volumes and long sea transports.

During delivery of Filtralite, it can sometimes be necessary to temporarily store the material. Filtralite filter medias can be stored outdoors without decrease of quality. It should be taken into consideration that the materials will adsorb water during rainfalls, which will make the media heavier and may increase transport costs. To avoid degradation of the big bags they should not be stored outdoors for more than 6 months. Filtralite P should not be stored outdoors, as rainfall may wash out parts of the material, which may result in reduced efficiency of the media.

Filtralite are inert ceramic particles with a dense shell surrounding a porous core.

Filtralite is an expanded clay product with high porosity. The pores are of varying sizes from small micro pores to larger pores (1-2 mm), most of them linked in labyrinthlike structure. By crushing the expanded clay beads, their large surface area is exposed. The large porous surface makes the Filtralite aggregates perfect for different types of water treatment. Porosity and density are controlled during manufacture of Filtralite. Dry particle densities can be produced in the range of 500-1600 kg/m3, with a corresponding dry bulk density of 300-900 kg/m3.

During the burning of the clay, strong bonds are created. Consequently the beads are unnaffected by any traditional gases or liquids, and release of harmful substances is avoided. Resistance to chemical breakdown is very high, and the acid loss is minimal.

Despite its low density and high porosity Filtralite has a high abrasion and impact resistance. Material strength is dependent on particle density. When particle density is increased, resistance to abrasion and physical impacts is increased.

In the production of Filtralite, clay is fed into long rotary kilns. The clay takes a few hours to pass through the rotary kiln, where the clay is dried, pelletised and expanded at temperatures reaching 1200oC. Expansion takes place when the organic matter stored in the clay combusts and the gas formation generates pores. The expanded clay pellets are then screened, sorted and if required crushed into different gradings according to customers requirements.

Filtralite is inert ceramic particles with a dense shell surrounding a porous core.This makes it suitable for use in different drinking water treatment processes, such as:

  • Physical filtration
  • Biological filtration
  • Pre-treatment for desalination

Drinking water treatment

Filtralite's large pore volumes and surface areas make it an ideal media for biological treatment of drinking water. Biofilm processes are excellent for treating raw water containing ammonia, manganese, iron etc. Tests have shown that Filtralite works perfectly in these kinds of processes. In conventional filtration processes Filtralite can be used in different ways.

In dual media filters Filtralite can be used in combination with sand. Tests have shown that Filtralite operates as well as or better than traditional filter media in these types of filters. Filtralite can not only be used in traditional drinking water treatment, but also in treatment of saline water. In desalination plants one of the most important parts is the pre-treatment process. Filtralite is an excellent filter media for use in pre-treatment filters in desalination plants.

Physical Filtration

Filtration of water is themost traditional type of watertreatment. Filtralite has the ideal properties to work as a good filter media in both mono and dual media filters for filtration of coagulated water.

Compared to traditional filter media like sand and anthracite Filtralite has much higher porosity, which gives lower initial head loss, slowe rhead loss build up and higher storage capacity. These advantages result in much longer filter runs between backwashes, which mean reduced energy and water consumption and higher water production, giving reduced operating costs.

By replacing sand with Filtralite in single mediafilters the operating timebetween backwashes can beextended by up to 500%. Fordual media filters a changefrom sand and anthraciteto the dual media FiltraliteMono-Multi, consistingof two different qualitiesof Filtralite, can give up to800% longer filter runs. Ifonly the top layer is replacedwith Filtralite and the bottomlayer of sand is kept the filterruns can be extended by upto 50%.

For existing filters withlow backwash velocities a change from sand to Filtralite will help in keeping the filters clean, as Filtralite is much lighter than sand and therefore need lower backwash rates for cleaning. Filters with Filtralite can be operated within a large range of filtration rates. The filtration rate will always be dependent of the configuration of the filter and the treatment process. Existing Filtralite filters operatefrom about 2 m/h up.

Biological filtration

In biological filters bacteria attach to the filter media and a biofilm arises on the surfaces of the filter grains. A large available surface area for biofilm growth is one ofthe most essential properties of filter media used in biofilmprocesses. The crushed Filtralite grains have a largesurface area, resulting in Filtralite being an ideal media for use in biological treatment processes.

Tests have shown that Filtralite is as good as or better than alternative carrier materials for biological treatment of drinking water. Ammonia, iron, manganese and other bio degradable substance scan be effectively removed in biological treatment using Filtralite as a carrier media. An important factor for an efficient biological treatment process is the time the wateris in contact with the biofilm. The most common way to quantify the contact time is the Empty Bed Contact Time (EBCT), which is defined as the time the water needs forpassing through the entire filter volume.

The needed EBCT vary for different water qualities and treatment systems, but about 20 minutes is quite normal for many systems. To be able to define the correct EBCT for a specific system it is recommended to run a pilot test. Existing Filtralite biofilters operate with filtration rates.