INTEC took part in the tender of the Rügen water supply and wastewater treatment association in 2016 and was awarded the contract for its innovative and environmentally friendly two-stage fluidized bed incineration system with heat recovery via a thermal oil system for the drying process. The sewage sludge recycling plant in Bergen utilizes all of the sewage sludge produced on the islands of Rügen and Hiddensee with an annual capacity of 10,000 tons.

In the first step, sewage gas is obtained in the digestion tower. The energy contained in the sewage gas is used in a combined heat and power plant with an output of 0.33 MW_el and 0.36 MW_th to generate electricity and heat to cover the energy requirements be used in the sewage treatment plant. The digested sewage sludge is dewatered to around 25% dry matter [TS] using a centrifuge and reaches the INTEC contact dryer via a solids pump, where it is dried to a DM content of around 50%, so that combustion of the sludge is prevented Sewage sludge is possible without additional fuel. The dryer has a water evaporation capacity of 0.31 t H₂O/h and uses the waste heat from sewage sludge incineration. After sludge drying, the sewage sludge is thermally utilized in a two-stage fluidized bed furnace, which enables a larger control range for combustion and achieves low harmful gas emissions due to the optimized air flow. In a downstream waste heat boiler, the heat generated during combustion is removed from the flue gas in order to supply the sewage sludge drying and the sewage treatment plant's heating system with sufficient energy. The flue gas from combustion is cleaned using a flue gas purification system consisting of an electrostatic filter, reactor and commercial filter. The cleaned exhaust air is then discharged via a chimney.

SCOPE OF INTEC:

• Complete EPC (engineering, procurement and construction) for the thermal oil heated sludge dryer 
• Fluidized bed incineration
• Waste heat recovery (ETA thermal oil boiler)
• Flue gas treatment 
• Other accessories including plant components to optimise the plant