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CN Consulting + Baustoff-Vertriebsgesellschaft mbH
Vierlander Str. 7
21502 Geesthacht
Phone. +49 4152 40 81
Fax: +49 4152 812 22


What questions can we answer for you?

How many products are currently used for CN Bio filters?

For the CN Bio filter technology we recommend three different expanded clay products. These are supplemented by a fourth expanded clay product for use in constructed wetlands.


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In which ranges are the bulk densities?

According to our performance declarations, the current bulk densities, depending on the product, are between 245 and 290 kg/m³.

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What particle sizes are available as CN filter material?

The particle size spectrum ranges from 2 to 20 mm and is specified and offered depending on the individual application. In our data sheets on biological water purification and filter units for use in plant-based purification systems, we provide detailed information on the corresponding particle sizes.

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How efficient is the CN expanded clay filter material?

The porosity of our products is second to none and offers absolutely excellent conditions for optimum water flow through the filter bed. For the water management systems, the use of our products means that they can filter a larger volume of water with the same filter volume. In this way, our products help to reduce operating costs for the operator. Amortization on conventional filter materials usually occurs after only a few years.

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Is CN expanded clay, in all its particle sizes, a sustainable product?

Our CN Filter expanded clay product line consists of 100 % clay, or more precisely expanded clay, and is therefore a natural product. This is mined in open-cast mines and the later areas are naturally renatured. The resources are always optimally used in compliance with the legal regulations. Thus new stable ecosystems are created in the renaturation, where a natural regeneration ability stands in the foreground.

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What are the performance characteristics of CN expanded clay 4 - 10 mm broken as a plantable filter body?

  • CN Blähton 4 - 10 mm crushed is a ceramic filter unit and specially manufactured for use in plant-based purification systems.
  • Due to the grain structure, this material offers a large surface area. The surface that can be colonised is approx. 60 m²/l.
  • Decisive for the efficiency of a constructed wetland is, for example, a high population density of the filter body as well as a large contact area to the waste water.
  • The grain structure, grain composition and chemical neutrality also ensure an ideal plant soil for reduction plants.
  • The water-bearing surface is approx. 400 m²/l.
  • The material is frost-proof and structurally stable.
  • CN expanded clay 4 - 40 mm crushed is easy to clean and immediately reusable.
  • Our expanded clay is inert, biologically neutral, odourless, resistant to rot and rotting.
  • The material combines the advantages of a fine sand filter, large settlement area, with those of a gravel filter, high air and water permeability.
  • The irregularly shaped and stepped ceramic bodies counteract a so-called flow channel formation. This expanded clay thus has a favourable flow profile and ensures permanent turbulence in the filter bed.

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Are the CN expanded clay filter materials certified?

Yes, of course our filter products are subject to certification according to:


  • EN IOS 9001 : 2015 (Quality-Management)
  • EN ISO 14001 : 2015 (Environmental Management)

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The CN expanded clay is very light, where can it be used as filter material?

Due to the very light weight, our CN expanded clay naturally floats up. The use of our filter materials is therefore preferably suitable for filter bins, filter cartridges, filter chambers or filter nets as well as fluidized bed reactors and similar closed systems. Our particle size 10 - 20 mm, as closed grain, is mainly used in trickle filters and strip plants.

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Which delivery forms are available for the CN Construct products?

We are able to offer a wide range of delivery forms depending on the needs and size of the customer and/or the company. Bulk goods can be delivered by silo vehicle or in a tipper / walking floor lorry. Two different sizes of bigbags are available as packaging units as well as the standard bagged product in 50-l bags

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Is supply availability dependent on the location of the operation?

[No, we deliver our products all over Germany and, of course, also worldwide. We generally deliver to the location specified or requested by our customer.

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How long is the usual delivery period?

As a rule, the delivery time within Germany is approx. 8 - 10 days. Of course, we also address this point in detail in our individual offer.

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Phone. +49 4152 40 81 · Fax: +49 4152 812 22 ·
© 2017 CN Consulting + Baustoff- Vertriebsgesellschaft mbH