Witkamp, Geert Jan
van Loosdrecht, Mark C.M.
KAUST DepartmentBiological and Environmental Sciences and Engineering (BESE) Division
Environmental Science and Engineering Program
Water Desalination and Reuse Research Center (WDRC)
Permanent link to this recordhttp://hdl.handle.net/10754/631562
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AbstractKinetics of iron reduction, formation of vivianite and the microbial community in activated sludge from two sewage treatment plants (STPs) with low (STP Leeuwarden, applying enhanced biological phosphate removal, EBPR) and high (STP Cologne, applying chemical phosphate removal, CPR) iron dosing were studied in anaerobic batch experiments. The iron reduction rate in CPR sludge (2.99 mg-Fe g VS-1 h-1) was 3-times higher compared to EBPR sludge (1.02 mg-Fe g VS-1 h-1) which is probably caused by its 3-times higher iron content. Accordingly, first order rate constants in both sludges are comparable (0.06 ± 0.001 h-1 in EBPR vs 0.05 ± 0.007 h-1 in CPR sludge), thus potential rates in both sludges are comparable. The measured Fe(III) reduction rates suggest that all iron in STP Leeuwarden and STP Cologne can be turned over within 15 h and 44 h respectively. Mössbauer spectroscopy and X-ray diffraction (XRD) indicated vivianite formation within 24 h in both sludges. After 24 h, 53% and 34% of all iron were bound in vivianite in the EBPR and CPR sludge respectively. Next generation sequencing (NGS) showed that the microbial community in the CPR sludge comprised more genera with iron-oxidizing and iron-reducing bacteria. Iron reduction and vivianite formation commence once activated sludge is exposed to oxygen free conditions. Our study reveals that the biogeochemistry of iron in STPs is very dynamic. By understanding the interactions between iron and phosphate crucial processes in modern sewage treatment, such as chemical phosphate removal or phosphate recovery from sewage sludge, can be optimized.
CitationWang, R. et al., 2019. Fe(III) reduction and vivianite formation in activated sludge. Separation and Purification Technology. Available at: http://dx.doi.org/10.1016/j.seppur.2019.03.024.
SponsorsThis work was performed in the TTIW-cooperation framework of Wetsus, European Centre Of Excellence For Sustainable Water Technology (www.wetsus.nl). Wetsus is funded by the Dutch Ministry of Economic Affairs, the European Union Regional Development Fund, the Province of Fryslân, the City of Leeuwarden and the EZ/Kompas program of the “SamenwerkingsverbandNoord-Nederland”. We thank the participants of the research theme “Phosphate Recovery” for their financial support and helpful discussions.