Process & contact
Charlene® - ReCord
Member of ESPP
Updated 8/2024
Input materials
Dry sewage sludge or other dried organic wastes (composts, food waste, wood waste, industrial sludge, digestate).
Maximum 25 % water.
Output products
P-salt:
- as sludge, with 20% solid content, can be evaporated to solid granules.
- Organic Carbon: < 0.5% DM
Nutrient content (%/DM):
- P: 5 – 8 %
- N: 3 – 7 %
- Ca: 5 – 13%
Contaminants:
- Fe, Al: 1 – 6%/DM
- Zn: < 1500 pp
- Pb: < 120 pp
- Cu: < 500 ppm
- pathogens, pharmaceuticals: not-detectable
Biocoal:
- as solid pellets or powder:
water: < 20%.
- Organic Carbon: > 45 %/DM.
Applications: as carbon source in steel production, as porous sorbent
Heat energy from dried input materials:
- as hot water / oil / air (e.g. 4.5 MJ/kgDM for dried sewage sludge).
- may be partly used for precipitate evaporation.
Process description
Integrated process based on slow pyrolysis, then chemical leaching of the biochar (after washing in water), then precipitation of phosphate salt from the eluates.
Specific one step leaching with nitric acid, then sequential leaching and precipitation using acids, potassium hydroxide and calcium chloride. These result in a precipitated phosphate salt and a biocoal with reduced inorganic content.
Contaminants are partly retained in the biocoal, partly transferred to the P-salt.
References
A. Salimbeni et al., Sustainability, 15(19): 14620, 2023. https://doi.org/10.3390/su151914620
A. Salimbeni, et al., Water 2023, 15, 1060. https://doi.org/10.3390/w15061060
Operating status
The technology has been applied with TRL 5 in a pilot unit of 50 lt/h (picture) and a new multi-batch unit at TRL 7, of 500 l/h capacity is under construction.
95 - 99% of phosphorus in input material is recovered in phosphate salts.