Removal of contaminants of emerging concern from the supernatant of anaerobically digested sludge by O3 and O3/H2O2: Ozone requirements, effects of the matrix, and toxicity

Digestate is a rich source of nutrients that can be applied in agricultural fields as fertilizer or irrigation water. However, most of the research about application of digestate have focused on its agronomic properties and neglected the potential harm of the presence of contaminants of emerging con...

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Bibliographic Details
Published in:Environmental research 2023-10, Vol.235, p.116597, Article 116597
Main Authors: Moradi, Nazanin, Vazquez, Carlos Lopez, Hernandez, Hector Garcia, Brdjanovic, Damir, van Loosdrecht, Mark C.M., Rincón, Francisco Rubio
Format: Article
Language:English
Subjects:
Contaminant of emerging concern
Digestate
Matrix effect
Ozonation
Ozone dose
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Summary:Digestate is a rich source of nutrients that can be applied in agricultural fields as fertilizer or irrigation water. However, most of the research about application of digestate have focused on its agronomic properties and neglected the potential harm of the presence of contaminants of emerging concern (CECs). Aadvanced oxidation processes (AOPs) have proved to be effective for removing these compounds from drinking water, yet there are some constrains to treat wastewater and digestate mainly due to their complex matrix. In this study, the feasibility to remove different CECs from digestate using O3 and O3/H2O2 was assessed, and the general effect of the matrix in the oxidation was explained. While the lab-scale ozonation provided an ozone dose of 1.49 mg O3/mg DOC in 5 h treatment, almost all the compounds were removed at a lower ozone dose of maximum 0.48 mg O3/mg DOC; only ibuprofen required a higher dose of 1.1 mg O3/mg DOC to be oxidized. The digestate matrix slowed down the kinetic ozonation rate to approximately 1% compared to the removal rate in demineralized water. The combined treatment (O3/H2O2) showed the additional contribution of H2O2 by decreasing the ozone demand by 59–75% for all the compounds. The acute toxicity of the digestate, measured by the inhibition of Vibrio fisheries luminescence, decreased by 18.1% during 5 h ozonation, and by 34% during 5 h O3/H2O2 treatment. Despite the high ozone consumption, the ozone dose (mg O3/mg DOC) required to remove all CECs from digestate supernatant was in the range or lower than what has been reported for other (waste-)water matrix, implying that ozonation can be considered as a post-AD treatment to produce cleaner stream for agricultural purposes. [Display omitted] •Ozonation is an effective post-AD treatment to produce cleaner digestate.•Ozonation removed contaminates of emerging concern from digestate in less than 1 h.•The digestate matrix decreased the contaminants removal rate by more than 90%.•Dosing H2O2 decreased the required ozone dose by 59%.
ISSN:0013-9351
1096-0953
1096-0953
DOI:10.1016/j.envres.2023.116597