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- Takman, Maria, et al.
(author)
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Biological degradation of organic micropollutants in GAC filters–temporal development and spatial variations
- 2024
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In: Journal of Hazardous Materials. - : Elsevier. - 0304-3894. ; 472
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Journal article (peer-reviewed)abstract
- The capacity for organic micropollutant removal in granular activated carbon (GAC) filters for wastewater treatment changes over time. These changes are in general attributed to changes in adsorption, but may in some cases also be affected by biological degradation. Knowledge on the degradation of organic micropollutants, however, is scarce. In this work, the degradation of micropollutants in several full-scale GAC and sand filters was investigated through incubation experiments over a period of three years, using 14C-labeled organic micropollutants with different susceptibilities to biological degradation (ibuprofen, diclofenac, and carbamazepine), with parallel 16S rRNA gene sequencing. The results showed that the degradation of diclofenac and ibuprofen in GAC filters increased with increasing numbers of bed volumes when free oxygen was available in the filter, while variations over filter depth were limited. Despite relatively large differences in bacterial composition between filters, a degradation of diclofenac was consistently observed for the GAC filters that had been operated with high influent oxygen concentration (DO >8 mg/L). The results of this comprehensive experimental work provide an increased understanding of the interactions between microbial composition, filter material, and oxygen availability in the biological degradation of organic micropollutants in GAC filters.
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| 2. |
- Takman, Maria
(author)
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From removal of organic micropollutants to municipal wastewater reuse - technological and social perspectives
- 2024
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Doctoral thesis (other academic/artistic)abstract
- In this thesis, wastewater reuse was investigated from technological and social perspectives, based onwhich the thesis was divided into two parts. In the first part, the removal of chemical and microbialcontaminants by full-scale and pilot-scale granular activated carbon (GAC) filters, in different processcombinations, was examined. In the second part, the perceptions of reused wastewater were studiedthrough a discourse analysis and compared with those of desalinated seawater, which is anotheralternative water source.The results showed that the treatment of wastewater with a process combination of a membranebioreactor, GAC filtration, and disinfection with ultraviolet radiation improved its quality to a level thatapproached that of drinking water. Limits on some organic micropollutants, such as pharmaceuticals, aregenerally not included in drinking water legislation or legislation for irrigation with reused wastewater,adding insecurities to the evaluation of water quality. Nevertheless, the water was treated to a highdegree and potentially constitutes a beneficial supplementary resource for irrigation or drinking waterproduction during drought or times of water scarcity. Whether the water criteria need to be complementedwith additional parameters merits further investigation.Organic micropollutants are removed by GAC filters primarily through adsorption but also throughbiological degradation. Measurements from a full-scale GAC filter indicated degradation of certainpharmaceuticals, which was confirmed in laboratory experiments with granules from various GAC filters.The degradation appeared to be affected specifically by the oxygen concentration in the filters and byoperation time.In the second part of the thesis work, the discourses over wastewater reuse and desalination on theSwedish islands of Öland and Gotland were examined and compared with general discourses identifiedfrom literature. Wastewater reuse and desalination are ways of producing drinking water whengroundwater and surface water resources are not sufficient and are often compared in the literature. Theresults showed that the local discourses often had similarities with the general ones and that there weredifferences between the two islands. Desalination on Gotland seemed to be more controversial thanwastewater reuse and desalination on Öland, and the perceptions of wastewater reuse and desalinationwere affected by many factors, such as visions and values with regard to welfare or sustainability andother political topics—for example local industries.
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