Hunter, Sarah Magarrill;
(2025)
Nutrient Chemical Structure & Anaerobic Digestion.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
As global warming continues to accelerate, the combined challenges of fossil fuel burning and food waste must be tackled to minimise heating potential of the gases released to the atmosphere. Anaerobic digestion (AD) offers a carbon neutral way to convert wastes to heat and power. Traditionally, substrates for anaerobic digestion have been limited to conventional waste streams (such as wastewater), but as this expands, there is a need to understand fundamental links between the chemical structure and digestion potential. This will enable better modelling strategies (by use of kinetics, ADM1 and artificial intelligence techniques). This thesis assesses variability in digestions kinetics of various substrates (sugars, amino acids, fatty acids, carbohydrates, proteins and lipids) by batch biogas potential tests. It explores relationships between chemical structure and digestion using kinetic models and extrapolating key parameters (total biogas production, production rate and lag time). Significant predictors of digestion kinetics include pyranose content, solubility, amylopectin content as well as saturated fat content. The kinetic models were used to predict continuous digestion behaviour. Using the ADM1 model, initialized with biogas potential test data, 150 days of continuous digestion of glucose, proteins, starch, and fibre was accurately described. ANN models were also tested for predicting biogas production. Multilayer perceptrons trained on 3, 10, and 14 days of data showed improved accuracy with increasing number of days, but also increasing complexity. In summary, this study explored the impact of chemical structure within nutrient classes and considered if this can be used to improve predictability of biogas production using a variety of modelling techniques.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | Nutrient Chemical Structure & Anaerobic Digestion |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Copyright © The Author 2025. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Civil, Environ and Geomatic Eng |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10208672 |
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