Unravelling key factors controlling vivianite formation during anaerobic digestion of waste activated sludge

Xiaodi Hao*, Wenbo Yu, Tugui Yuan, Yuanyuan Wu, Mark C.M. van Loosdrecht

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)


As a product of phosphorous recovery from anaerobic digestion (AD) of waste activated sludge (WAS), vivianite has received increasing attention. However, key factors controlling vivianite formation have not yet been fully addressed. Thus, this study was initiated to ascertain key factors controlling vivianite formation. A simulation of chemical equilibriums indicates that interfering ions such as metallic ions and inorganic compounds may affect vivianite formation, especially at a PO43-concentration lower than 3 mM. The experiments demonstrated that the rate of ferric bio-reduction conducted by dissimilatory metal-reducing bacteria (DMRB) and the competition of methane-producing bacteria (MPB) with DMRB for VFAs (acetate) were not the key factors controlling vivianite formation, and that ferric bio-reduction of DMRB can proceed when a sufficient amount of Fe3+ exists in WAS. The determined affinity constants (Ks) of both DMRB and MPB on acetate revealed that the KHAc constant (4.2 mmol/g VSS) of DMRB was almost 4 times lower than that of MPB (15.67 mmol/g VSS) and thus MPB could not seriously compete for VFAs (acetate) with DMRB. As a result, vivianite formation was controlled mainly by the amount of Fe3+ in WAS. In practice, a Fe/P molar ratio of 2:1 should be enough for vivianite formation in AD of WAS. Otherwise, exogenously dosing Fe3+ or Fe2+ into AD must be applied in AD.

Original languageEnglish
Article number118976
Number of pages8
JournalWater Research
Publication statusPublished - 2022

Bibliographical note

Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care
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  • affinity constant (K)
  • Anaerobic digestion
  • dissimilatory metal-reducing bacteria (DMRB)
  • methane-producing bacteria (MPB)
  • Vivianite
  • waste activated sludge (WAS)


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