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CN Consulting + Baustoff-Vertriebsgesellschaft mbH
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21502 Geesthacht
Phone. +49 4152 40 81
Fax: +49 4152 812 22


Special expanded clay as a biofilm carrier for bacteria

Because it offers numerous ecological advantages, biological purification of sewage and exhaust air is becoming increasingly important. As a natural filter material, CN BIO FILTER made of special expanded clay permits environmentally friendly and sustainable biofiltration.

The biofiltration principle

Biofiltration of water and air replicates the self-purification processes that occur in nature, for example, in streams and rivers. In these processes, pollutants are degraded into non-poisonous, odourless substances such as carbon dioxide and water through the metabolic activity of bacteria and other microorganisms. For this biochemical oxidation, solid filter material is inoculated with bacteria.

Expanded clay as a filter material

The filter material must satisfy many requirements. A large contact surface is necessary to permit a high population density of the strains of bacteria. At the same time, a steady flow through the filter bed must be ensured and the filter bed must be structurally stable and rotproof. CN BIO FILTER made of specially expanded clay meets all of these criteria. With specifically engineered particle sizes and shapes and the special properties of the pore structure, it forms an ideal substrate for inoculation with microorganisms. Moreover, it is biologically and chemically neutral and easy to clean or dispose of in an eco-friendly manner. Because it is very light, it floats, making it suitable primarily for applications in closed systems such as fixed- and fluidised-bed reactors or barrel filters.

CN BIO FILTER is available in the following particle sizes:

Particle size Biofilm area
2 - 4 mm, crushed approx. 70 m2/l
4 - 10 mm, crushed approx. 60 m2/l
10 - 20 mm approx. 12 m2/l

CN BIO FILTER for constructed wetlands

CN BIO FILTER with 4-10-mm particles of crushed expanded clay was conceived especially for use in constructed wetlands. Constructed wetlands are a type of treatment plant in which wastewater is purified in a basin planted predominantly with reeds. The microorganisms are introduced in the area of the plant roots. The expanded clay of the CN BIO FILTER stands out by virtue of a large contact surface to the water, provision of a hospitable environment for microorganisms and an advantageous flow profile. Simultaneously, the particle structure and composition and chemical neutrality ensure an ideal planting ground for reposition plants. As a plantable filter body, it promotes root growth and provides for optimum aeration. CN BIO FILTER is a natural, weather-resistant product and offers constantly high quality for especially efficient constructed wetlands.

We will be happy to inform you in detail about the use and volume requirements of our CN BIO FILTER products. Feel free to contact us if we can be of service.

Phone. +49 4152 40 81 · Fax: +49 4152 812 22 ·
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