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Full-scale biological phosphorus removal: quantification of storage polymers, microbial performance and metabolic modelling
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Resumo(s)
Enhanced biological phosphorus removal (EBPR) can be applied in wastewater treatment
plants (WWTPs), as a sustainable and efficient way to remove phosphorus from
wastewater and hence reduce its impact on eutrophication. This work characterises the
performance, metabolism and identity of the microbial EBPR communities in full-scale
WWTPs. The accurate quantification of the internal storage compounds, namely polyhydroxyalkanoate
(PHA) and glycogen, is crucial to the characterisation of EBPR. The
optimal glycogen and PHA quantification methods were sensitive to the heterogeneity
of the sample, in terms of its microbial structure (floccular or granular) and, for PHA,
in terms of the size and the number of substituents of the monomers forming the copolymer.
Additionally, by characterising six full-scale EBPR WWTPs, in terms of their
overall performance, microbial identity and metabolism, the composition of polyphosphate
accumulating organisms (PAOs) was fairly similar in all plants. Also, a warmer climate
was not sufficient to justify a higher presence of glycogen accumulating organisms
(GAOs). Differing levels of denitrifying PAOs were obtained in different plants and the
involvement of the tricarboxylic acid (TCA) cycle in the anaerobic metabolism of PAOs
was observed. Furthermore, a metabolic model developed in this study, which incorporates
the involvement of the anaerobic TCA cycle and a new description of the aerobic
maintenance processes, was able to accurately describe the chemical cycling of soluble
and intracellular compounds, while requiring a simple calibration procedure. A series of
simulations demonstrated that lower acetate concentrations in the feed and higher aeration
retention times would favour the TCA cycle metabolism over the glycolysis pathway,
which would explain why the former has been more frequently encountered in WWTPs
and the latter in lab-scale enriched cultures.
Descrição
Dissertação para obtenção do Grau de Doutor em
Engenharia Química e Bioquímica
Palavras-chave
Enhanced biological phosphorus removal Anaerobic TCA cycle Glycogen PHA Metabolic modelling