Austria, Belgium, Germany, Spain and Switzerland

GCTU, Hariri Chemical Process Engineering,InsPyro, Inerco, M.A.L., M.I.T. Metallurgy & Inorganic Technology,Montanuniversität Leoben, Universität Stuttgart, SGL Carbon


Sander Arnout
Kapeldreef 60
3001 Heverlee

T. +32 1 629 84 91



RecoPhos is a thermo-chemical process involving the fractioned extraction of phosphate and heavy metals from sewage sludge ash at high temperatures under reducing conditions. The chemical principle of the core reaction is modelled on the “Wöhler process”, in which phosphates react with carbon and silicon dioxide in a furnace and is reduced to phosphorus. RecoPhos follows a novel approach by using the InduCarb retort, where a coke bed is heated inductively, and the reduction of the phosphorus contained in the sewage sludge ash takes place in a thin melt film on the surface of the coke particles. The reduced phosphorus can evaporate from the film without significantly reacting with other elements and can subsequently be retrieved either as white phosphorus or oxidised into phosphoric acid.

The RecoPhos process does not only transform problematic waste with high heavy metal content into valuable phosphorus but also produces several streams of secondary raw materials that can be used in other industrial applications. The process will enable optional use of waste materials as heat sources, reducing agents or additives. Concepts to recover a maximum of the heat of the high-temperature process will be developed, turning RecoPhos into a near-zero waste process.

RecoPhos will be developed using lab-scale experiments and state-of-the-art modelling and simulation methods to investigate the thermodynamic and chemical processes taking place within the reactor. They will provide the basis for the implementation of a fully operational bench scale reactor and the design of a pilot scale plant. The economic, environmental and social impact of the RecoPhos process will be investigated in a market study and a Life Cycle Assessment.

The RecoPhos process is designed to:

  • Enhance the purity of the phosphorus recovered by using the InduCarb technique.

  • Increase the efficiency of phosphorus recycling through generation of usable by-products, use of waste materials and heat recovery.

  • Reduce Europe’s dependence on phosphate imports.

  • Counteract the depletion of natural phosphate sources.

FUNDING TYPE: EU FP7 Eco-Innovation
BUDGET: € 4.500.000
SUBSIDY: € 3.200.000

Contact us


Department of Materials Engineering
Kasteelpark Arenberg 44
3001 Leuven, Belgium