Process & contact
www.susphos.com
Contact:
Updated 3/2024
Input materials
Sewage sludge incineration ash, other P-containing ashes.
Planned: other phosphate-rich materials with low levels of organics, e.g. vivianite.
Output products
Phosphoric acid, or mono- or diammonium phosphate, fertiliser or technical quality.
The SusPhos solvent extraction process leaves a residual mineral stream, containing gypsum (calcium sulphate from the sulphuric acid reaction), sand from silicates in ash, aluminium and iron. Heavy metals in the sewage sludge (copper, lead …) are 95% removed from the phosphoric acid and immobilised in the residual mineral stream. SusPhos intends that this mineral stream can be valorised in e.g. building materials.
Process description
The input materials are reacted with concentrated sulphuric acid (similar to existing industry Single Super Phosphate type processes) then a proprietary solvent is used to extract phosphoric acid. Purified phosphoric acid can be stripped out of the solvent, or reacted to phosphate chemicals which can be separated from the solvent, without requiring ion-exchange or membrane filters. The solvent is then recycled back to the process.
Heavy metals are largely removed and rendered inert in insoluble calcium minerals: e.g. >95% of Cd, Hg, Cu, Zn …
Operating status
25 kg/day pilot operated in Leeuwarden (NL) for over two years 2021-2023, using sewage sludge incineration ash and other dry, P-rich, low-organics materials.
A contract has been signed (February 2024, see ESPP eNews n°84) with SNB (Slibverwerking Noord-Brabant, The Netherlands) to design a full-scale P-recovery from ash plant, establish the business plan and define cooperation, allowing a decision on investment in a full-scale plant to then be taken. The objective is for the full-scale plant to be operational by 2027.