Recycling of sewage sludge is not only a method of disposal, but it also is a means to generate a new raw material with a commercial value. Compostable sewage sludge can serve as a basic substance for fertilisers and soil conditioning agents used in agriculture or landscape management and land recovery technologies.

"Instant mixtures" heading toward new markets

Soil Concept Sàrl, a small Luxembourg company, has developed a new composting method for sewage sludge in two pilot plants. In close co-operation with two public waterworks in the Saar-Lux-region and scientists and marketing experts from France, Belgium and Germany, the company has developed "instant mixtures" for different applications and is now establishing new outlets and distribution chains for their products.

Composting is done in silos lined with a membrane, which are equipped with a specially designed mixing machine. The sewage sludge is thoroughly mixed with old leaves, bark and sand, composted at high temperature with suction aeration, and finally stored. Within 12 or 16 weeks a hygienic, odourless compost is forming.

The construction of a composting plant at industrial scale will be completed in Diekirch by the beginning of July. Running at full capacity from October onwards, the plant will treat between 12,000 and 15,000 tons of sewage sludge annually. Siden (Syndicat Intercommunal de Depollution des Eaux Residuaires du Nord), for which Soil Concept is operating the plant, expect the plant to operate on a profitable basis after four years.

At the same time, Soil Concept is carrying out a project in order to make the results of the development work available in Europe to water authorities, potential supplying companies and final users of compost products. (Source: aqua press Int. 05/99)

Information & Contact:
Soil Concept
L-1150 Luxembourg
Tel. 45 56 36 or 25 42 73