Pilot-scale magnetic recovery of vivianite from digested sewage sludge

Pilot-scale magnetic recovery of vivianite from digested sewage sludge

Wijdeveld, W. K. (Wetsus, Centre for Sustainable Water Technology)
Prot, T.J.F. (TU Delft BT/Environmental Biotechnology; Wetsus, Centre for Sustainable Water Technology)
Sudintas, G. (Wetsus, Centre for Sustainable Water Technology)
Kuntke, P. (Wetsus, Centre for Sustainable Water Technology; Wageningen University & Research)
Korving, L. (Wetsus, Centre for Sustainable Water Technology)
van Loosdrecht, Mark C.M. (TU Delft BT/Environmental Biotechnology)

2022

Phosphorus (P) is an essential resource for food production and chemical industry. Phosphorus use has to become more sustainable and should include phosphorus recycling from secondary sources. About 20% of P ends up in sewage sludge, making this a substantial secondary P source. There is currently a technological gap to recover P from sludge locally at wastewater treatment plants (WWTP) that remove P by dosing iron. Vivianite (Fe₃(PO₄)₂•8(H₂O)) is the main iron phosphate mineral that forms during anaerobic digestion of sewage sludge, provided that enough iron is present. Vivianite is paramagnetic and can be recovered using a magnetic separator. In this study, we have scaled up vivianite separation from lab-scale to bench- and pilot-scale. Bench-scale tests showed good separation of vivianite from digested sewage sludge and that a pulsation force is crucial for obtaining a concentrate with a high P grade. A pilot-scale magnetic separator (capacity 1.0 m³/h) was used to recover vivianite from digested sewage sludge at a WWTP. Recirculating and reprocessing sludge allows over 80% vivianite recovery within three passes. A concentrated P-product was produced with a vivianite content of up to 800 mg/g and a P content of 98 mg/g. P recovery is limited by the amount of P bound in vivianite and can be increased by increased iron dosing. With sufficient iron dosing, the vivianite content can be increased, and subsequently more P can be recovered. This would allow compliance with existing German legislation, which requires a P recovery larger than 50%.

HGMS
Magnetic separation
Phosphorus recovery
Pilot scale operation
Vivianite

http://resolver.tudelft.nl/uuid:cae7d007-b3bc-4c6b-b429-bb4ee548690e

https://doi.org/10.1016/j.watres.2022.118131

0043-1354

Water Research, 212

Institutional Repository

journal article

© 2022 W. K. Wijdeveld, T.J.F. Prot, G. Sudintas, P. Kuntke, L. Korving, Mark C.M. van Loosdrecht