Process & contact
RSR (Green Sentinel)
(Recovered Sludge Resources)
Dewatered sewage sludge (after e.g. filter-press or centrifuge)
1) PecuPhos®: a mixed aqueous solution of minerals, including phosphates with c. 75% water / 25% minerals w/w, which can be used as an input to mineral fertiliser production.
The solution is pH 3 and contains:
- 1.5 – 4 % P
- 2-4 % Ca
- 0.5 – 1.5 % K
- sulphates, chlorides, etc.
Iron is < 1.3%, Heavy metals are low, e.g. Cd, Hg, Cr < 13ppm, Cu and Zn < 50-500ppm.. Organic carbon is < 30ppm
2) PecuPower® = alternative fuel - comparable to pellets (water content < 10%, thermal value 4 800 MWh/t) or PecuGrow® = a refined sludge which can be composted
The RSR module uses a special solvent to adjust pH-value and ensure high dewatering of sludge (PecuLeach®) to extract up to 75% of the phosphorus (and of other minerals) from the dewatered sewage sludge into an aqueous solution (PecuPhos®).
The solvent is recycled to enrich the aqueous solution with phosphorus and minerals.
Optionally, solid phosphate can be precipitated from this solution (as a mixture of brushite, struvite …).
Heavy metals are also extracted by the solvent, then precipitated to a separate solid fraction for disposal (c. 60-80% of e.g. Hg, Cu, Zn, Fe in dewatered sludge are separated out to this fraction).
The remaining organic fraction can be further processed either by drying to produce fuel (PecuPower®) or is processed to compost (PecuGrow®)
Pilot installations have been tested at 8 kg dewatered sludge input per hour scale for 2 weeks.
A first semi-full scale installation is contracted for Wels municipal sewage works, Austria (165 000 p.e., operating chemical P-removal), commissioning planned mid 2022. This will intially treat 2 500 t/y wet weight dewatered sludge input, that is c. 30% of the sewage from the works. Extension to treat 100% of the works’ sludge is planned as a second stage