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bioRxiv · 10.1101/2023.12.21.572732

Resource-efficient nitrogen removal from source separated urine with partial nitritation/anammox in a membrane aerated biofilm reactor

Timmer, M. J.·De Paepe, J.·Van Winckel, T.·Spiller, M.·Spacova, I.·De Paepe, K.·Pintelon, I.·Lebeer, S.·De Vos, W.·Lasseur, C.·Ganigue, R.·Udert, K.·Vlaeminck, S. E.
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Abstract

Source separation and decentralized urine treatment can cut costs in centralized wastewater treatment by diverting 80% of the nitrogen load in sewage. One promising approach for nitrogen removal in this context is partial nitritation/anammox (PN/A), reducing the aeration demand by 67% and organics dosage by 100% compared to nitrification/denitrification. Whilst previous studies with suspended biomass have encountered stability issues during PN/A treatment of urine, a PN/A biofilm was hypothesized to be more resilient. Its use for urine treatment was pioneered here for maximum rates and efficiencies in the energy efficient membrane-aerated biofilm reactor (MABR). Nitrogen removal rates of 1.0 g N L-1 d-1 and removal efficiencies of 80-95% were achieved during a 335-day stable operation at 28{degrees}C on stabilized (pH>11), diluted urine (10%). A balance between N2 and NO3 - formation was observed whilst optimizing the supply of O2 and was rate limiting for the conversion towards N2. Short-term operation on less- and undiluted urine yielded N removal rates of 0.6-0.8 g N L-1 d-1 and removal efficiencies of 93% on 66% urine and 85% on undiluted urine. Metataxonomic analysis and fluorescence in-situ hybridization confirmed the presence of biofilms consisting of nitrifiers (Nitrosomonas, Nitrospira) at the membrane side and anammox bacteria ("Candidatus Brocadia") at the anoxic bulk side. The findings suggest that a biofilm approach to PN/A treatment of urine overcomes stability issues, and a PN/A-MABR has significant potential for resource efficient decentralized treatment. In human long-duration deep-space missions, this gravity-independent technology could produce N2 to compensate artificial atmosphere losses whilst facilitating water recovery from urine. [GRAPHICAL ABSTRACT, COLOR] O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=101 SRC="FIGDIR/small/572732v1_ufig1.gif" ALT="Figure 1"> View larger version (39K): org.highwire.dtl.DTLVardef@1680b0corg.highwire.dtl.DTLVardef@1ad822dorg.highwire.dtl.DTLVardef@3d5c4borg.highwire.dtl.DTLVardef@764841_HPS_FORMAT_FIGEXP M_FIG C_FIG

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Timmer, M. J., De Paepe, J., Van Winckel, T., Spiller, M., Spacova, I., De Paepe, K., Pintelon, I., Lebeer, S., De Vos, W., Lasseur, C., Ganigue, R., Udert, K., Vlaeminck, S. E.. 2023-12-22. Resource-efficient nitrogen removal from source separated urine with partial nitritation/anammox in a membrane aerated biofilm reactor. https://doi.org/10.1101/2023.12.21.572732

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