How Expanded Clay Works as
Filtering Material

How Expanded Clay Works as Filtering MaterialExpanded clay is best used in biofilters shaped like tanks with a double bottom. Wastewater passes through the immobile filtering layer, separating into two phases. A biological film forms on the surface, consisting of microorganisms that break down organic matter. The residue settles, and clean water continues through the system.
Expanded clay is widely used in both residential and industrial treatment systems. In Russia, it is used at over 50 facilities and 20 municipal water networks. It is also popular in Germany, Norway, Belarus, and Scandinavia. The material has proven effective even for filtering heavily oil-contaminated wastewater.

Modern household and industrial treatment facilities are designed as multi-stage systems. This construction helps minimize the penetration of harmful substances and pathogens into soil and water bodies. Expanded clay granules are used as filter media.
Studies show that for effective dirt retention and to reduce hydraulic resistance, the material should be placed in two layers: larger fractions at the bottom and finer ones on top. This method offers approximately 1.5 times higher efficiency compared to conventional quartz-based filters.
Expanded clay can also be added to the polishing chamber of a septic tank, where water is further disinfected by aerobic bacteria. The expanded clay environment provides ideal conditions for these organisms. The natural filler, made from fired clay, retains its properties for years, thanks to its resistance to moisture, temperature changes, and other environmental impacts. Its use makes wastewater treatment more cost-effective and easier to maintain.

USE OF EXPANDED CLAY IN FILTRATION

Expanded clay is well known not only as a building material, an insulator, or a component in landscape design and hydroponics, but also as an effective means for purifying, filtering, and disinfecting wastewater in treatment facilities. It is of natural origin, has a low weight and a porous structure, which allows it to be used to cleanse wastewater. As an absorbent, it lets large volumes of wastewater pass through while capturing dirt and large solid particles.