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Process & contact



Member of DPP

Updated 2/2022

Input materials

Dewatering liquor from sewage sludge digestate, containing soluble phosphate, optionally after re-dissolution of phosphates.

90 – 95 % of soluble phosphate (orthophosphate) is removed and recovered in final product

Output products

Granular calcium  phosphate.

Final product contains up to 13% P DM.

Water content of final product is around 50 – 60% after standing to dry (dries easily due to pore structure).

Organic carbon content of final product not yet available and depends on input stream.

Plant availability of P has been demonstrated in pot trials but P-solubility in NAC as specified in EU Fertilising Products Regulation is not yet available.

Process description

Crystallisation of calcium phosphate from dewatering liquor by means of SIMPur, a specific calcium silicate hydrate (CSH), which releases SiO2 / silicon compounds and takes up phosphorus, with 7:1 ratio of input consumed SIMPur CSH:P in final product.

SIMPur is produced by processing the natural CSH mineral tobermorite to tailored granulometry.36simphos

Contaminant levels in SIMPur are low. Contaminant levels in the in final product depend on input stream, with the following results from tests to date:
- Cu, Hg, Cd : not detectable
- Zn: 10 mg/kg DM
- Fe: 2 mg/g DM
- Al: 1 mg/kg DM

Operating status

Operational test in 2016: mobile unit, inflow 0.5 m3/h, operated continuously for c. 3 months using real sewage sludge digestate.

Planned operation in 2022 with capacity 7.5 m3/h treating part of the sludge digestate centrate at the WWTP Neuburg an der Donau, Germany (67 000 p.e).

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