Carlota Tayà

Carlota Tayà started her carrier as a Chemical Engineer of Universitat Autònoma de Barcelona in 2007. In 2008 she obtained the Master degree of Environmental Technologies from Universitat Autònoma de Barcelona and started her thesis research. During 6 month of her PhD thesis she went to UNESCO-IHE (Institute for Water Education) in Delft, Netherlands. And in 2013, she received her doctoral degree on Environmental Sciences from Universitat Autònoma de Barcelona. Nowadays she is a postdoctoral researcher at Universitat de Vic, Catalonia.

Tittle thesis: Facing current EBPR bottlenecks in view of full‐scale implementation

Abstract: Enhanced biological phosphorus removal (EBPR) has been extensively studied, but its implementation at full-scale is still associated to unpredictable failures. Furthermore, when EBPR is implemented simultaneously to nitrogen and organic matter removal, some negative interactions have been found, while individually does not occur.

This thesis aims to improve the understanding of EBPR and solve some of the issues reported when EBPR is implemented in wastewater treatments together with biological removal of nitrogen and organic matter.

The research conducted in this thesis has two different approaches within this framework. On the one hand, the negative interaction between the nitrogen and phosphorus removal processes has been studied. On the other hand, the possibility to use alternative carbon sources, also used in nitrogen removal, has been assessed by developing novel strategies focused on obtaining new syntrophic consortia for application in EBPR.

In chapter 4, new insights for simultaneous nitrogen and phosphorus removal are presented. These strategies are based on the bioaugmentation of PAO microorganisms in nitrification/denitrification systems. A cycle configuration with an anoxic phase with two feedings and an aerobic phase was used to achieve nitrification, denitrification and EBPR. A key point for the success of this strategy was to provide proper operational conditions to avoid rising problems. Enough aerobic phase length was required to ensure complete PHA depletion for PAO microorganisms, which avoided the carbon source availability required for denitrification.

In this context, the interaction of different intermediates of the nitrogen removal process, such as nitrite and nitrate, on the EBPR processes was studied. The conclusion of such experiments was that intermediate products of the nitrogen removal process, such as nitrate, can affect EBPR process when PAO microorganisms have not been previously acclimated to these conditions.

Low concentration of volatile fatty acid in wastewaters has been also reported to be one of the main hurdles problems to implement EBPR process in full-scale WWTPs. For this reason, Chapter 5 presents the studies done in order to use different carbon sources for EBPR. Two carbon sources commonly used in nitrogen removal processes, namely methanol and glycerol, were tested, resulting in a cost reduction when nitrogen and phosphorus were removed simultaneously in wastewaters with low COD content. Two different strategies were assessed: first, the direct replacement of conventional carbon source (propionic acid) to the desired carbon source in a PAO-enriched sludge system. The second strategy, a novel one, was to develop a consortium of anaerobic sludge, comprising previously selected microorganisms, and PAO where the first ferment the complex carbon source to short-chain volatile fatty acids (i.e. acetic and propionic acid) which are subsequently used by the PAO in the EBPR process.

Finally, Chapter 6 presents the study of a new strategy to achieve a predominantly PAO-enriched sludge, removing GAO, which uptake significant proportions of the carbon source available for EBPR. The application of this strategy resulted in the 85% of PAO in the enriched sludge, washing out GAO of the system.

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