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Finding new biotechnological solutions - Advancing microalgal wastewater treatment with beneficial bacteria / ALEXANDRA GIMBLETT

Swansea University Author: ALEXANDRA GIMBLETT

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Abstract

Microalgal wastewater treatment systems may solve several problems with traditional systems. They can cope with high nutrient loads, do not require a supplementary oxygen input, and contribute to a circular economy. However, there are still challenges presented when upscaling these systems. Certain...

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Published: Swansea University, Wales, UK 2025
Institution: Swansea University
Degree level: Master of Research
Degree name: MRes
Supervisor: Sonnenschein, E., and Webster, T. U.
URI: https://cronfa.swan.ac.uk/Record/cronfa68885
Abstract: Microalgal wastewater treatment systems may solve several problems with traditional systems. They can cope with high nutrient loads, do not require a supplementary oxygen input, and contribute to a circular economy. However, there are still challenges presented when upscaling these systems. Certain bacterial strains can promote microalgal growth due to the mutualistic symbioticrelationships formed between these microbes. Therefore, the purpose of this study was to analyse microalgal microbiomes that have been cultivated using wastewater and identify potentially beneficial bacteria within these microbiomes with the aim to make microalgal wastewater treatment systems viable at large scales. DNA extraction, 16S rRNA amplicon sequencing, and co-cultivation experiments were conducted to analyse the biodiversity of the Tetradesmus obliquus microbiome when cultivated on agricultural digestate, identify possible beneficial bacterial strains for use withinT. obliquus wastewater treatment systems, and investigate the impact of specific bacterial strains onT. obliquus growth. The T. obliquus microbiomes cultivated on digestate had significantly different bacterial community compositions with lower species diversity and evenness compared to the T. obliquus microbiomes cultivated using a control medium. A bacterial strain belonging to the Pseudomonadaceae family was found in great abundance within the digestate-treated microbiomes and appeared to rapidly grow in abundance within this environment after the first day of cultivation. Co-cultivation analysis found that an isolate identified as Psuedomonas laurentiana, which shared significant sequence similarity to the bacterial strain belonging to the Pseudomonadaceae family, significantly increased T. obliquus growth. The isolate identified as P. laurentiana may therefore be suitable for use within and advance T. obliquus wastewater treatment systems. Further co-cultivation studies should be conducted within digestate and other wastewater environments at larger scales to determine if the consortia of T. obliquus and P. laurentiana are effective when trying to upscale T. obliquus wastewater treatment systems and make them more efficient.
Item Description: A selection of content is redacted or is partially redacted from this thesis to protect sensitive and personal information.
Keywords: Microalgae, bacteria, wastewater treatment, interactions.
College: Faculty of Science and Engineering