Sewage Sludge Incineration Plant to Grosswilfersdorf, Austria

Turnkey greenfield sewage sludge incineration plant enables environmentally friendly and economically viable treatment of municipal and industrial sludge without additional fuel consumption.

Completed in 2011, the Outotec sewage sludge incineration plant treats municipal and industrial sewage sludge from several local wastewater treatment plants. It carries out thermal sludge treatment based on fluidized bed (FB) technology – an environmentally friendly and economically viable solution for treating municipal and industrial sludge without additional fuel consumption.

Built on a site with no wastewater treatment infrastructure, the plant caters to 100% third-party sludge from various sources. A key design criterion was the ability to process varying sludge qualities. Successful financing was based on secured long-term contracts.


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Delivery year
Sewage sludge


  • Greenfield installation for 100% third-party sludge
  • Varying sludge quality requiring a high degree of flexibility
  • Strict emissions limits


  • Turnkey sewage sludge incineration plant delivery
  • Thermal treatment of sewage sludge in an Outotec Fluidized Bed Incinerator with open-nozzle grid
  • Thermal oil dryer that uses recovered heat from incineration


• Minimal environmental emissions
• No auxiliary fuel required for treatment during normal operation
• Excess energy supplied to neighboring production plant


Sludge from various sources is stored in a sludge bunker (capacity 300 m3) and a portion is dried using a contact dryer operated with thermal oil. The vaporized water from the dryer is condensed in a condensation unit, which includes heat recovery. The dried sludge is then mixed with wet sludge before being injected into the FB incinerator, which has an open-nozzle grid. The plant has a capacity of 30,000 t/y and requires no external fuel for normal operation, and to prevent odor emissions the primary air is taken from the reception hall.

The heat of the hot flue gases from the FB incinerator is recovered using a thermal oil boiler and used in the sludge dryer and to preheat the air, with the excess sold to a neighboring production plant. The flue gas cleaning system starts with a cyclone to separate the bulk of the ash from the flue gas, which can then be used for phosphorous recycling. After the evaporation cooler the dry sorption system injects hydrated lime and activated carbon, and then filters through a baghouse. The cleaned flue gas exits the plant through the stack.

Project scope

Outotec was responsible for the design, manufacture, and supply of all equipment, the installation and commissioning activities, including all construction work, as well as start-up support and operator training assistance. Furthermore, Outotec was also awarded an operation and maintenance contract for the plant.

Design data

Sludge dryer  
Inlet DS content 20-35%
Heat consumption 1,300 kW
Outlet DS content 75-80%
Fluidized bed incinerator  
Throughput 2,000 kg/h at >48% DS
Incinterator head temperature 870-900°C
Fluidizing air 2,250 Nm3/h at <200°C
Secondary air 1,800 Nm3/h at <200°C
Heat recovery boiler  
Thermal oil 230/180°C
Excess available heat 1,200 kW at 85°C
Flue gas cleaning  
Flue gas quantity wet 6,200 m3/h
Flue gas outlet temperature 140°C
Emissions (acc. AVV standards) (at STP)  
Dust <10 mg/m3
HCI <10 mg/m3 
HF <0.7 mg/m3 
SO2 <50 mg/m3 
NOx (as NO2) <150 mg/m3
CO <50 mg/m3 
Pb+Sn+ <0.5 mg/m3 
PCDD/PCDF <0.1 mg/m3
Outotec Sewage Sludge Incineration Plant 30

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