Thermal treatment of sewage sludge and phosphorus recycling technology

The SEWAPHOS Process

In the context of future requirements of sewage sludge disposal regulations, the project Sewaphos offers an overall concept. This concept is focused on the best utilisation of the resource and energetic potential of sewage sludge. The thermal recovery is carried out in an energy optimized mono-incineration plant. The added value comes from the production of phosphoric acid from sewage sludge ashes which is a bulk chemical with numerous uses in the chemical industry

Process graph

Process graph



PolyChemie GmbH

Considering economical aspects, the dewatering efficiency is expected to play a key role in future. We offer a comprehensive range of polymer flocculants and a recognised and applied Know-How. Defoamers, antiscalant and coagulants complete our chemical portfolio. In order to increase further the dewatering efficiency, mechanical or electrochemical processes such as the ZetaOptimizer can be implemented.


FMI Process

The thermal utilisation of dewatered sludge with the patented Sun Sand incineration technology in fluidized bed oven presents economical and ecological advantages. The intensive turbulence in the fluid bed ensures a homogenous temperature gradient. In this way this technology complies with the European legislation for gaseous emissions.


FMI Process

Investment and operating costs are lower than for ordinary ovens because this technology has been designed without refractory bricks. Our modular design allows a high operating flexibility for central or local solutions from 2,000 to 50,000 tons dewatered sewage sludge per year. Thanks to a Start & Stop operating mode we provide more process flexibility. It allows the oven to be started or stopped, if necessary, with short transitory stages.


TU Bergakademie Freiberg

Our patented process for phosphorus recovery consists in a wet chemical leaching step with an integrated acid recovery and the selective separation of phosphoric acid. The raw phosphoric acid is filtered out from the undissolved ash particles. Customised qualities of phosphoric acid are obtainable. The yield of phosphorus recovery is about 60 to 80 %. The mass reduction of the sludge ashes is between 30 and 40 %.


TU Bergakademie Freiberg

In this way the utilisation of the phosphorus contained in sewage sludge is not only limited to its application as fertilizer in agriculture. Interesting fields of application could be treatment of metal surfaces such as anodising and polishing baths, passivation of iron and zinc, corrosion protection or other range of application for the chemical industry.


Poll Umwelt- und Verfahrenstechnik

Regarding the mineral resource recovery, the recycled material such as pure phosphoric acid, calcium hydroxide and building material resistant against chemicals will be commercialised.


Practical solutions for the thermal utilisation of sewage sludge and for phosphorus recovery are becoming increasingly relevant and important. In this context we try to adopt a Zero-Waste approach. Our international project SEWAPHOS offers you innovative and new solutions.


Thermal treatment
Mechanical sludge dewatering
Polymeric flocculants

PolyChemie GmbH Right arrowTo the website

Thermal treatment

FMI Process S.A. Right arrowTo the website

Phosphorus recovery
Binding of heavy metals

Institut für Technische Chemie Right arrowTo the website

Raw materials management

Poll Umwelt- und Verfahrenstechnik GmbH Right arrowTo the website


Do you want to learn more about us and are interested in receiving further information?

SEWAPHOS 22 rue du Garat
42152 L´HORME
Phone icon+33 4 77 22 25 50