Chemistry
The core process comprises a thermite reaction of sewage sludge ash constituents with aluminium.
The lowest quality aluminium scrap can be used.
Aluminium acts as reducer and as energy carrier and therefore:
very less external energy is required;
reduction is carbon free.
The process is flexible in feedstocks.
Phosphate reduction is near complete.
Three step and compact processing
Limited preheating;
Mixture conditioning;
Conversion and products collection.
The maximum volumetric throughput equals the throughput of ash.
Products
White phosphorus; inherently purified by distillation from the reactor;
High aluminium oxide slag to be applied in civil works and refractory materials;
Metallic ferrophosphorus, directly applied or to be converted into a coagulant and a valuable P-product.
Total achievable P-recovery efficiency is unprecedented.
Sustainability
Zero waste, no waste water, no flue gas from conversion;
Zero fossil fuel possible;
Typical CO2 savings: 1.000 kg CO2/ton sewage sludge ash;
Immobilization of heavy metals;
Destruction of PFAS (expected, not yet proven).
Business case
Capex is low because of the few step, scaleable and compact processing;
All products are well marketable;
At usual price levels, a sound payback period is calculated.