Every year, hundreds of thousands of tons of wet sewage sludge are produced worldwide, containing a number of recyclable substances, including phosphorus in large quantities. In Switzerland e.g. the phosphorus contained in the effluents is equivalent to approximately the same amount of phosphorus imported annually in the form of fertilizer.
At the same time, there is currently an intensive exploitation of the natural resources of phosphorus in countries such as China, Morocco, USA and Russia, so that these resources will no longer be infinitely and indefinitely available. This situation suggests a recycling of recyclables in sewage sludge, and in particular of phosphorus. The sewage sludge is usually about 96% water and about 4% of dry matter. Therefore, a drying of sewage sludge is necessary.
The Swiss company KAWE AG, based in Untersiggenthal, manufactures and supplies belt dryers of various sizes, with the aid of which the sewage sludge is dried in various processes before its further processing, thereby considerably reducing its volume and weight.
Kawe builds both standard systems in common sizes such as ED12, ED24 or ED51 as well as customer-specific systems which are tailored in detail to the operational customer conditions (waste heat utilization, sewage sludge quantities, sewage sludge type, multi-level processes, etc.).
The belt dryers from KAWE AG (System Easy Dry) have the following main features and advantages:
- Water evaporation rate: 500 - 3000 kg / h (depending on the humidity of the sewage sludge before drying)
- Modular structure → easy scalability
- Special product distribution system → homogeneous distribution of product over the belt
- Dry air flow from above → no dust in the circulating air
- Integrated product cooling zone → ready to use product
- Efficient safety concept, fire and explosion protection concept (low-temperature process, fire-extinguishing system by means of sprinkler, mechanical tub cleaning, CO detection, dust detection, high-temperature detection)
- Use of stainless materials → durability
- External return of the belt → easy cleaning and maintenance
- Special backmixing system → good product granulation at the entrance to the dryer
- Circulation fans heat- and sound-insulated → high energy efficiency and occupational safety
- Recirculation of exhaust air → high energy efficiency and environmental friendliness
- Automated process monitoring → unattended operation possible (low operator presence)
Overall, the belt dryers of KAWE AG (System Easy Dry) are characterized by a simple and clear structure, low operating costs, high efficiency and environmental friendliness (low energy consumption), as well as high availability and robustness. The product delivered from the dryer is of high quality and can be used immediately. The dryers are easily adaptable to different types of sewage sludge.
Reference systems of the Easy Dry sludge dryers have been successfully in operation for several years and can also be inspected with the operators, provided they are planned accordingly.