Maxit - Expanded Clay for Water Treatment and Filtration

The Maxit group provides the building market with premix and exclay products and other related services. It operates in more than 30 countries with the emphasis on Europe.

The Maxit group manufactures lightweight aggregates that are either sold as finished products, or 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. 

FILTRALITE AGGREGATES FOR WATER TREATMENT

The Maxit group specialises in the use of Filtralite, an expanded clay product with high porosity. Its pores are of varying sizes, from small micro pores to larger pores (1mm to 2mm). They are linked in a labyrinthine 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 the manufacture of Filtralite. Dry particle densities can be produced in the range of 500kg/m³ to 1,600kg/m³, with a corresponding dry bulk density of 300kg/m³ to 900kg/m³.

During the burning of the clay, strong bonds are created. The beads are therefore unaffected by traditional gases or liquids, and the 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.

MAINTAIN THE STRATIFICATION OF TWO FILTER LAYERS AFTER A BACKWASH

In dual-media down-flow filters, which are regularly backwashed, there are two important factors:

• Decreasing grain size in the direction of the flow
• Avoiding intermixing of filter layers

Increasing the efficiency of the filter bed by increasing its depth maintains the stratification of the two filter layers after a backwash. The settling velocity of individual filter grains in water will determine their stratification behaviour when water alone is used for the final phase of a backwash.

FILTRALITE IS EXCELLENT REGARDING HEAD LOSS, SLUDGE STORING CAPACITY AND FILTRATED WATER QUALITY

Surface water from a lake has been used for testing Filtralite in parallel, dual-media downstream pilot filters. The humic raw water, which is common in the northern hemisphere, contained a low level of turbidity.

Filter I contained Filtralite with size 0.8mm to 1.6mm on the top of sand grains sized between 0.4mm and 0.8mm. Filter II contained anthracite of an equal size on the top of the same type of sand.

Filtralite proved to have superior or equal properties in the parameters of head loss, sludge storing capacity and filtrated water quality.

FILTRALITE IS AN EXCELLENT METHOD OF BIOLOGICAL TREATMENT OF DRINKING WATER

In biological filters bacteria attach themselves 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 of the most essential properties of filter media used in biofilm processes.

The available surface area is dependent on the grain size and density. The crushed Filtralite grains have a larger surface area than the round grains, and are normally preferred in biofilm processes. Tests have shown that Filtralite is an excellent method of biological treatment of drinking water.

Filtralite is certified for use in drinking water applications in Europe according to European Norm EN 12905.

DURABLE AND EFFICIENT TOOLS FOR WASTEWATER TREATMENT

There are huge challenges all over the world regarding the handling of wastewater in order to preserve a sustainable future. Filtralite is trying to contribute to this by creating durable and efficient tools for wastewater treatment.

Filtralite filter media is used as a carrier for biofilms in biological processes, and as a granular filter media for particle removal. Numerous plants worldwide are using Filtralite in nitrification, post- and pre-denitrification and BOD removal applications.

EFFICIENT AND ENVIRONMENT-FRIENDLY WAYS OF TREATING DOMESTIC WASTEWATER

Filter beds with prefilter are simple, efficient and environment-friendly ways of treating domestic wastewater from detached houses and holiday homes. The operation and maintenance levels are greatly reduced in comparison to traditional compact plants.

These systems can also be adapted to suit clusters of houses, schools, kindergartens and small companies.