Continuous biodegradation of 14C-labeled micropollutants and their transformation products in ozonated wastewater
(2025) VVAM05 20251Chemical Engineering (M.Sc.Eng.)
- Abstract
- Organic micropollutants comprise a diverse set of molecules, varying both with regard to the frequency of their use, as well as the potential harm they can inflict upon aquatic ecosystems. Ozonation has been recognized as an efficient method for their abatement, due to its ability to selectively oxidize molecular groups commonly found on organic molecules. Micropollutants are, however, rarely degraded by ozonation alone. Instead, partial oxidation results in various ozone transformation products, the harmfulness of which are largely uncertain and, in some cases, proven significant. To address this issue, a biological post-treatment step has been acknowledged as important to degrade these transformation products and reduce the toxicity of... (More)
- Organic micropollutants comprise a diverse set of molecules, varying both with regard to the frequency of their use, as well as the potential harm they can inflict upon aquatic ecosystems. Ozonation has been recognized as an efficient method for their abatement, due to its ability to selectively oxidize molecular groups commonly found on organic molecules. Micropollutants are, however, rarely degraded by ozonation alone. Instead, partial oxidation results in various ozone transformation products, the harmfulness of which are largely uncertain and, in some cases, proven significant. To address this issue, a biological post-treatment step has been acknowledged as important to degrade these transformation products and reduce the toxicity of outgoing water. Still, the ability of wastewater treatment plants to remove ozone transfor-mation products using the above methods require further study; this largely pertain to two key process parameters – ozone dose and hydraulic retention time.
14C-labelled micropollutants and liquid scintillation counting were used to monitor the degra-dation of parent compounds and ozone transformation products during ozonation and biodeg-radation experiments; the selected micropollutants were sulfamethoxazole, sulfadiazine, ibu-profen, diclofenac, carbamazepine and trimethoprim. Ozonation experiments were conducted where all 14C-labelled micropollutants were subjected to various amounts of ozone stock solu-tion, yielding the following doses: 0, 0.3, 0.6, and 1.0 mg O3/mg DOC. CO2 traps were then placed in bottles with ozonated water, capturing any 14CO2 formed from mineralization of a labelled position. The small bottles were incubated for about two days, enabling complete transfer of 14CO2 to the traps, followed by scintillation measurements both on water and the traps. The results were put in relation to a previous study of the same, but non-labelled, pollu-tants using the same ozone doses; this study showed that all selected micropollutants were completely transformed already at 0.3 mg O3/mg DOC, except ibuprofen, for which 1.0 mg O3/mg DOC was required. The ozonation experiments of this thesis showed a mineralization which increased with ozone dose for all compounds but remained partial even at 1.0 mg O3/mg DOC; considering the analysis of non-labelled pollutants, this confirmed the presence of ozone transformation products and the need for a post-treatment step to abate them. This seem to be the case especially for trimethoprim, for which ozonation resulted only in slight mineralization for all ozone doses. The biodegradation experiments were continuous, as ozo-nated water was pumped through small-scale reactors, equipped with MBBR biocarriers. The water was collected in large bottles which, following probable equilibrium in the reactors, were changed to small bottles equipped with CO2 traps. These were then treated similarly to those acquired from the ozonation experiments.
For a hydraulic retention time of 30 minutes, mineralization of the labelled position increased with ozone dose for all compounds, showing an increased bioavailability for ozone transfor-mation products. This is an unambiguous implication of the applicability of ozonation and bi-odegradation; trimethoprim can be used as a clear example, considering its frequent detection in the effluents of many wastewater treatment plants, and the limited mineralization from ozonation. Furthermore, a hydraulic retention time of 30 minutes does not hinder the effect of different ozone doses, indicating an applicability of ozone and post-treatment in wastewater treatment plants. Lastly, hydraulic retention times of 1 and 2 hours were tested for sulfameth-oxazole and sulfadiazine, neither showing significant differences in scintillation results for collected water compared to corresponding results for 30 minutes. Considering that an in-creased ozone dose yields an increased mineralization for all compounds during a hydraulic retention time of 30 minutes, it can be further suggested that all biodegradation occurs within this timeframe. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/9200230
- author
- Lindgärde, Josef LU
- supervisor
-
- Per Falås LU
- organization
- alternative title
- Continuous biodegradation of 14C-labeled micropollutants in ozonated wastewater
- course
- VVAM05 20251
- year
- 2025
- type
- H2 - Master's Degree (Two Years)
- subject
- keywords
- 14C-labelling, Ozonation transformation products, Organic micropollutants, Water and environmental engineering
- report number
- 2025-04
- language
- English
- id
- 9200230
- date added to LUP
- 2025-06-16 15:26:21
- date last changed
- 2025-06-16 15:26:21
@misc{9200230,
abstract = {{Organic micropollutants comprise a diverse set of molecules, varying both with regard to the frequency of their use, as well as the potential harm they can inflict upon aquatic ecosystems. Ozonation has been recognized as an efficient method for their abatement, due to its ability to selectively oxidize molecular groups commonly found on organic molecules. Micropollutants are, however, rarely degraded by ozonation alone. Instead, partial oxidation results in various ozone transformation products, the harmfulness of which are largely uncertain and, in some cases, proven significant. To address this issue, a biological post-treatment step has been acknowledged as important to degrade these transformation products and reduce the toxicity of outgoing water. Still, the ability of wastewater treatment plants to remove ozone transfor-mation products using the above methods require further study; this largely pertain to two key process parameters – ozone dose and hydraulic retention time.
14C-labelled micropollutants and liquid scintillation counting were used to monitor the degra-dation of parent compounds and ozone transformation products during ozonation and biodeg-radation experiments; the selected micropollutants were sulfamethoxazole, sulfadiazine, ibu-profen, diclofenac, carbamazepine and trimethoprim. Ozonation experiments were conducted where all 14C-labelled micropollutants were subjected to various amounts of ozone stock solu-tion, yielding the following doses: 0, 0.3, 0.6, and 1.0 mg O3/mg DOC. CO2 traps were then placed in bottles with ozonated water, capturing any 14CO2 formed from mineralization of a labelled position. The small bottles were incubated for about two days, enabling complete transfer of 14CO2 to the traps, followed by scintillation measurements both on water and the traps. The results were put in relation to a previous study of the same, but non-labelled, pollu-tants using the same ozone doses; this study showed that all selected micropollutants were completely transformed already at 0.3 mg O3/mg DOC, except ibuprofen, for which 1.0 mg O3/mg DOC was required. The ozonation experiments of this thesis showed a mineralization which increased with ozone dose for all compounds but remained partial even at 1.0 mg O3/mg DOC; considering the analysis of non-labelled pollutants, this confirmed the presence of ozone transformation products and the need for a post-treatment step to abate them. This seem to be the case especially for trimethoprim, for which ozonation resulted only in slight mineralization for all ozone doses. The biodegradation experiments were continuous, as ozo-nated water was pumped through small-scale reactors, equipped with MBBR biocarriers. The water was collected in large bottles which, following probable equilibrium in the reactors, were changed to small bottles equipped with CO2 traps. These were then treated similarly to those acquired from the ozonation experiments.
For a hydraulic retention time of 30 minutes, mineralization of the labelled position increased with ozone dose for all compounds, showing an increased bioavailability for ozone transfor-mation products. This is an unambiguous implication of the applicability of ozonation and bi-odegradation; trimethoprim can be used as a clear example, considering its frequent detection in the effluents of many wastewater treatment plants, and the limited mineralization from ozonation. Furthermore, a hydraulic retention time of 30 minutes does not hinder the effect of different ozone doses, indicating an applicability of ozone and post-treatment in wastewater treatment plants. Lastly, hydraulic retention times of 1 and 2 hours were tested for sulfameth-oxazole and sulfadiazine, neither showing significant differences in scintillation results for collected water compared to corresponding results for 30 minutes. Considering that an in-creased ozone dose yields an increased mineralization for all compounds during a hydraulic retention time of 30 minutes, it can be further suggested that all biodegradation occurs within this timeframe.}},
author = {{Lindgärde, Josef}},
language = {{eng}},
note = {{Student Paper}},
title = {{Continuous biodegradation of 14C-labeled micropollutants and their transformation products in ozonated wastewater}},
year = {{2025}},
}