Pyrofluid™ is an advanced, safe and sustainable thermal treatment solution designed for the efficient removal of municipal and industrial dewatered sewage sludge. The process consists in a fluidized-bed incinerator that operates 24/7 at approximately 900°celsius in order to oxidize organic matter contained within the sewage sludge. It produces safe mineral residues while allowing energy recovery and ash recycling. Pyrofluid is capable of handling and ensuring in a few seconds full combustion of large quantities of sludge — 200 kilograms to 5 tons of dry solids per hour (sludge between 25 and 35% dryness) — from plants of varying capacities.

Pyrofluid™ is a fluidized-bed incineration technology that uses thermal oxidation to remove organic matter and other residues from dewatered municipal and industrial sewage sludge.


Water treatment legislation is becoming more and more stringent, increasing overall sludge production — a fact that encourages wastewater treatment plant designers to consider processes that not only eliminate the nuisance caused by sewage sludge but also recover energy and/or recycle the by-products of the treatment.
And this is exactly what we offer with Pyrofluid. Complying with the most strict emission standards, Pyrofluid is especially well suited for sludge incineration because it helps to ensure good dispersion of the solids, good solid-gas contact and a uniform temperature.

The fluidized-bed technology ensures a complete combustion with low excess of combustion air and the thermal energy it produces offers the advantage of being suitable for many purposes such as heating buildings or delivering electrical power through steam generation.

Depending on the characteristics of the ash produced by Pyrofluid, it can be recycled and then used to replace noble materials such as cement or natural materials such as kaolin in cement works, prefabricated concrete, or to stabilize landfill waste.

How Pyrofluid works

Once dewatered, the sewage sludge is fed into the fluidized-bed furnace in several points with a pump. The furnace consists of a layer of hot sand which is fluidized by the combustion air.

The sludge is sprayed directly onto the hot sand. The incineration is mainly carried out in the layer of sand at a temperature around  750° celsius before continuing on in the freeboard area, where the temperature increases up to 850 to 880° celsius.

After cooling, the flue gas is treated and cleaned with an electrostatic precipitator or a bag filter that removes more than 99% of the ash in order to comply with the present gas emission regulation IED 2010/75/EU and the BAT Conclusions 12/11/2019 in Europe, the United States Environmental Protection Agency (USEPA) in North America or local regulation in other areas of the world on waste incineration. Sodium bicarbonate and activated carbon are used to remove the acidic compounds and the heavy metals. Finally, the cleaned flue gas is emitted through the stack.


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Feature and benefits

  • 24/7 operation for maximum efficiency.
  • Easy, automated operation.
  • Long-term reliability: excellent resistance to high temperature, erosion and corrosion (no moving parts  in the hot zones). Some Pyrofluid units are 35 years old (Grenoble, Strasbourg).
  • Total destruction of pathogens.
  • Total mineralization of sludge.
  • Produce stable and recyclable by-products (ash, dust).
  • The ash produced constitutes around 10% of the dewatered sludge amount.
  • No odor.
  • Low maintenance costs.


Sludge valorization: making better use of your resources
Optimized management of effluents and wastewater.
Technologies, services and process expertise to meet environmental requirements, remove contaminants and transform wastewater into a resource.


A combination of digital tools and Veolia expertise that make all your water processes smarter, safer and more sustainable.

Resources & Product range


To best meet your needs, the Pyrofluid range includes 8 standard models with capacities ranging from 350 to 2,500 kg per hour of volatile matters: R28, R36, R43, R50, R56, R62, R67, R72.


Veolia Water Technologies has been offering complete sludge incineration plants since the 1970s, with Pyrofluid technology at their heart. These facilities have evolved to provide ever-higher levels of treatment quality, particularly in terms of gas emissions, and to enable ever-greater energy recovery. Our facilities now offer highly efficient environmentally friendly sludge treatment along with the possibility of producing heat or electricity (for use in a district heating network, for example).



Fanny Schwager

Incineration Process Manager, Engineering Department - Veolia Water Technologies



FAQ about Pyrofluid™

What is sewage sludge?

Sewage sludge is the semi-liquid by-product resulting from industrial or municipal wastewater treatment (human domestic waste and industrial waste). Due to the human domestic and industrial waste contained in wastewater, sewage sludge is a mixture of organic matter and valuable nutrients (such as nitrogen and phosphorus) that can be recycled and reused as soil fertilizer but can also contain pollutants such as heavy metals, chemicals, viruses, drug residues, radioactive material, etc. Therefore, it is important to treat them in order to prevent environmental pollution, unpleasant odors in residential areas, and health hazards.

What is a fluidized bed incinerator?

A fluidized bed incinerator is set with a bed of hot sand or other granular material to transfer heat directly to waste. It is especially useful for the removal of industrial and municipal dewatered sewage sludge.

Why is dewatering sludge important?

Dewatering sludge consists in removing most of the water from sludge by a centrifuge or a filter. It is important to achieve good sludge dryness during the dewatering stage, in order to reach auto-thermal operation. If dewatering is not effective enough to achieve good dryness, it may be necessary to add a pre-drying stage.

Is it possible to recover energy from sludge incineration?

Yes, Veolia Water Technologies has references of steam turbines on its sludge treatment plants, and of providing heat for a digestion unit in the plant (Warsaw in Poland, Saragozza in Spain, St Petersburg in Russia, Noisy-le-Grand in France, etc.). 

Is it possible to recycle ashes?

Yes it’s possible to recycle ashes, for example in road building.

Is it possible to recover phosphorus from ashes?

Yes, technologies do exist. In Germany, they will soon be mandatory.