Transformation of Fe-P Complexes in Bioreactors and P Recovery from Sludge: Investigation by XANES Spectroscopy

Ruo Hong Li, Jin Li Cui, Jia Hui Hu, Wei Jun Wang, Bing Li, Xiang Dong Li, Xiao Yan Li

Research output: Journal article publicationJournal articleAcademic researchpeer-review

31 Citations (Scopus)


The transformation of Fe-P complexes in bioreactors can be important for phosphorus (P) recovery from sludge. In this research, X-ray absorption near-edge structure analysis was conducted to quantify the transformation of Fe and P species in the sludge of different aging periods and in the subsequent acidogenic cofermentation for P recovery. P was readily removed from wastewater by Fe-facilitated coprecipitation and adsorption and could be extracted and recovered from sludge via acidogenic cofermentation and microbial iron reduction with food waste. The fresh Fe-based sludge mainly contained fresh ferrihydrite and amorphous FePO4 with sufficient accessible surface area, which was favorable for Fe-P mobilization and dissolution via microbial reaction. Ferric iron dosed into wastewater underwent rapid hydrolysis, clustering, aggregation, and slow crystallization to form hydrous iron oxides (HFO) with various complicated structures. With the aging of sludge in bioreactors, the HFO densified into phases with much reduced surface area and reactivity (e.g., goethite), which greatly increased the difficulty of P release and recovery. Thus, aging of P-containing sludge should be minimized in wastewater treatment systems for the purpose of P recovery.

Original languageEnglish
Pages (from-to)4641-4650
Number of pages10
JournalEnvironmental Science and Technology
Issue number7
Publication statusPublished - 7 Apr 2020

ASJC Scopus subject areas

  • General Chemistry
  • Environmental Chemistry


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