Université du Luxembourg
The impact of macro-substrate on micropollutant degradation in activated sludge systems.
Degree: 2019, Université du Luxembourg
Wastewater treatment plants are designed as a first barrier to reduce xenobiotic emission into rivers. However, they are not sufficient enough to fully prevent environmental harm of emerging substances in the water body. Therefore, advanced treatment processes are currently being investigated but their implementation is cost-intensive. The optimisation of the activated sludge treatment to enhance biological micropollutant removal could reduce operating costs and material. Although the impact of operational parameters, such as sludge retention time and hydraulic retention time on the xenobiotic removal have been investigated, the influence of the macro-substrate composition and load on micropollutant elimination causes a high degree of uncertainty.
This study focuses on the latter by analysing 15 municipal wastewater treatment plants, where variations in load and composition of the macro-substrate were expected. Assuming that macro-substrate shapes the biomass and triggers their activity, the impact of macro-substrate composition and load on xenobiotic degradation by microorganisms was analysed. It was hypothesised that on the one hand, a high dissolved organic carbon concentration might lead to enhanced xenobiotic degradation for certain substances due to a high microbial activity. The latter is assumed to be caused by a high labile dissolved organic carbon portion and the tendency for a shorter sludge retention time. On the other hand, a low dissolved organic carbon concentration, probably containing a predominant recalcitrant substrate portion, tends to a longer sludge retention time. Consequently, slow-growing and specialised microorganisms may develop, able to degrade certain xenobiotics. As a second question, the contribution of the autotrophic biomass to xenobiotic degradation was tested by inhibiting the autotrophic microorganisms during the degradation test. To additionally test the hypothesis, the impact of a readily biodegradable substrate (acetate) on the xenobiotic degradation was tested and the sensitivity of the fluorescence signal of tryptophan was used to analyse the impact of tryptophan on xenobiotic degradation. Degradation tests focusing on the removal of macro-substrate and micropollutants within 18 hours incubation in the OxiTop® system were performed. The OxiTop® system is known as fast and easy method for organic matter analysis in the wastewater. To assess the macro-substrate composition prior to and after the degradation test, three characterisation methods were applied. Firstly, to determine the labile and the rather recalcitrant portion in the dissolved organic carbon, absorbance was measured at 280 nm and further analysed. This was verified by the characterisation of both portions based on the oxygen consumption measurements. Secondly, to analyse the organic matter concerning its fluorescent properties, excitation-emission scans were run and analysed using the parallel factor analysis approach. Lastly, the chromophoric and fluorescent organic matter was separated via size-exclusion…
Advisors/Committee Members: Hansen, Joachim [superviser], Wilmes, Paul [president of the jury], Köhler, Christian [member of the jury], Abbt-Braun, Gudrun [member of the jury], Knerr, Henning [member of the jury].
Subjects/Keywords: micropollutants; macro-substrate; xenobiotic degradation; Engineering, computing & technology :: Civil engineering [C04]; Ingénierie, informatique & technologie :: Ingénierie civile [C04]
to Zotero / EndNote / Reference
APA (6th Edition):
Christen, A. (2019). The impact of macro-substrate on micropollutant degradation in activated sludge systems. (Doctoral Dissertation). Université du Luxembourg. Retrieved from http://orbilu.uni.lu/handle/10993/41195
Chicago Manual of Style (16th Edition):
Christen, Anne. “The impact of macro-substrate on micropollutant degradation in activated sludge systems.” 2019. Doctoral Dissertation, Université du Luxembourg. Accessed October 21, 2020.
MLA Handbook (7th Edition):
Christen, Anne. “The impact of macro-substrate on micropollutant degradation in activated sludge systems.” 2019. Web. 21 Oct 2020.
Christen A. The impact of macro-substrate on micropollutant degradation in activated sludge systems. [Internet] [Doctoral dissertation]. Université du Luxembourg; 2019. [cited 2020 Oct 21].
Available from: http://orbilu.uni.lu/handle/10993/41195.
Council of Science Editors:
Christen A. The impact of macro-substrate on micropollutant degradation in activated sludge systems. [Doctoral Dissertation]. Université du Luxembourg; 2019. Available from: http://orbilu.uni.lu/handle/10993/41195