Use of fermentation processes for improving the dissolution of phosphorus and its recovery from waste activated sludge

ABSTRACT

Recycling phosphorus from waste activated sludge has attracted a lot of interest to tackle the problem of phosphorus stocks depletion and the increase in food demand. In this study, the use of fermentation processes was investigated to enhance phosphorus dissolution from waste activated sludge to improve its recycling. Two fermentation processes, bioacidification and dark fermentation, were used on two different sludges fermented with wheat starch syrup in continuous operating conditions. Hydrogen yield from the co-substrate fermentation with waste activated sludge reached 3.9 mmolH₂.gCOD_cosubstrate⁻¹ yield during dark fermentation process and was negligible during bioacidification. Dissolved phosphorus in the waste activated sludge increased by 68% during bioacidification and by 43% during dark fermentation. In both processes, phosphorus dissolution was accompanied by iron, calcium and magnesium dissolution. Results show that fermentation enhances phosphorus dissolution in waste activated sludge to improve its recovery along with hydrogen and organic acids.

GRAPHICAL ABSTRACT

KEYWORDS:

• Fermentation
• dark fermentation
• bioacidification
• phosphorus
• phosphorus recovery

Acknowledgements

This study was part of the NWE Interreg Phos4you project which is funded by the European Regional Development Fund (ERDF) under grant NWE292.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by European Regional Development Fund: [grant number NWE292].