<abstract xmlns="http://www.w3.org/1999/xhtml"><p>The role of P content on the treatment and valorization of the liquid fraction of digestate, namely centrate, through microalgae-based technologies was evaluated in this study. The performance of four column photobioreactors, which were fed on diluted centrate with corrected (10 mg N/ mg P) and not modified (129 mg N/ mg P) N:P ratio, were monitored and compared. The results demonstrated that P shortage in the centrate affected neither the total nitrogen and COD removal rate nor the volumetric biomass productivity, suggesting that expensive addition of P salts is not necessary to maximize the efficiency of the process. On the contrary, the addition of P to the centrate promoted the ammonia oxidation process as higher nitrite production was observed in the photobioreactors with adjusted N:P ratio than in the ones fed with the non-adjusted N:P ratio. These findings were confirmed by fluorescence <italic>in-situ</italic> hybridization and quantitative PCR assays, which revealed a higher number of ammonia-oxidizing bacteria in the microalgal suspensions cultivated on centrate with P addition. In conclusion, the N:P ratio in the centrate seems to have a role in controlling the nitrification process rather than in the overall nutrient removal rate and biomass productivity of the microalgae-based system.</p></abstract>

The role of P content on the treatment and valorization of the liquid fraction of digestate, namely centrate, through microalgae-based technologies was evaluated in this study. The performance of four column photobioreactors, which were fed on diluted centrate with corrected (10 mg N/ mg P) and not modified (129 mg N/ mg P) N:P ratio, were monitored and compared. The results demonstrated that P shortage in the centrate affected neither the total nitrogen and COD removal rate nor the volumetric biomass productivity, suggesting that expensive addition of P salts is not necessary to maximize the efficiency of the process. On the contrary, the addition of P to the centrate promoted the ammonia oxidation process as higher nitrite production was observed in the photobioreactors with adjusted N:P ratio than in the ones fed with the non-adjusted N:P ratio. These findings were confirmed by fluorescence in-situ hybridization and quantitative PCR assays, which revealed a higher number of ammonia-oxidizing bacteria in the microalgal suspensions cultivated on centrate with P addition. In conclusion, the N:P ratio in the centrate seems to have a role in controlling the nitrification process rather than in the overall nutrient removal rate and biomass productivity of the microalgae-based system.

Effect of N:P Ratio on Microalgae/Nitrifying Bacteria Community in Agro-Digestate Treatment

Università degli Studi di Milano Bicocca

Environmental and Climate Technologies

This work is licensed under the Creative Commons Attribution 4.0 International License.

The role of P content on the treatment and valorization of the liquid fraction of digestate, namely centrate, through microalgae-based technologies was...

Effect of N:P Ratio on Microalgae/Nitrifying Bacteria Community in Agro-Digestate Treatment

Published Online: Sep 23, 2020

Page range: 136 - 148

DOI: https://doi.org/10.2478/rtuect-2020-0061

Keywords
Ammonia oxidation, centrate, microalgae-based technology, nutrient removal, P content

© 2020 Micol Bellucci et al., published by Sciendo

This work is licensed under the Creative Commons Attribution 4.0 International License.

Effect of N:P Ratio on Microalgae/Nitrifying Bacteria Community in Agro-Digestate Treatment

Published Online: Sep 23, 2020

Page range: 136 - 148

DOI: https://doi.org/10.2478/rtuect-2020-0061

KeywordsAmmonia oxidation, centrate, microalgae-based technology, nutrient removal, P content

© 2020 Micol Bellucci et al., published by Sciendo

This work is licensed under the Creative Commons Attribution 4.0 International License.

Keywords
Ammonia oxidation, centrate, microalgae-based technology, nutrient removal, P content