RT info:eu-repo/semantics/doctoralThesis
T1 Bioconversion of food waste into volatile fatty acids via anaerobic fermentation: Insights on operational disturbances and process scalability
A1 Afecto Gonçalves, Manuel João
A2 Universidad de Valladolid. Escuela de Doctorado
K1 Residuos alimentarios
K1 Anaerobic fermentation
K1 Fermentación anaerobia
K1 Food waste
K1 Residuos alimentarios
K1 Volatile fatty acids
K1 Ácidos grasos volátiles
K1 Operational perturbations
K1 Perturbaciones operacionales
K1 23 Química
AB The continuous growth of the global population and its social development have led to an increasing demand for food production. As a consequence, food waste (FW) generation has increased substantially, raising economic and environmental challenges. A proper valorization of these residues is essential for mitigating their negative environmental impacts and contributing to a circular economy. Among the potential technologies capable of treating and valorizing organic residues, anaerobic digestion (AD) is a sustainable bioprocess that has gained attention for converting organic matter into a biogas primarily composed of methane, given its high energy value. AD proceeds through several steps: hydrolysis, acidogenesis, acetogenesis and methanogenesis, where organic matter is solubilized into volatile fatty acids (VFAs) that are intermediate metabolites to ultimately produce biogas.VFAs are carboxylic acids with high industrial value due to their versatility as chemical building blocks for applications in the chemical, pharmaceutical, and food sectors. Traditionally produced via petrochemical routes, VFAs can alternatively be obtained through anaerobic fermentation (AF), an unbalanced AD where the final methanogenesis step is inhibited. This suppression allows the accumulation of VFAs rather than their conversion into methane. Although methods such as inoculum pretreatment and chemical additives have been explored to inhibit methanogens, these approaches are economically or energetically expensive. As an alternative strategy, operational parameters such as temperature, pH, hydraulic retention time (HRT), and organic loading rate (OLR) can be manipulated to favour acidogenic bacteria over methanogenic archaea, thereby enhancing VFA production.Despite the extensive research on AD optimization, the effects of tuning the operational conditions on AF’s efficiency and stability remain less understood. This knowledge gap hinders the development of AF for VFAs production, where process robustness and product stability are crucial. Understanding how changes in operational conditions affect the microbial populations and the metabolite profiles is key to optimize this process, particularly under real scenarios where the feedstock composition and operational factors may vary.This Thesis investigated the use of AF for the bioconversion of FW into VFAs by selecting operational parameters to promote VFA accumulation, identifying the behaviour of the microbial communities, and understanding the AF’s performance upon operational perturbation, which are often unavoidable at larger scales. Particular attention is given to identifying warning indicators of AF instability and exploring strategies for system recovery. Furthermore, this Thesis addressed the scalability of AF by studying its performance and robustness of the process at chemical and biological level across a gradual increase in reactor volumes.Overall, this work contributes with insights for attaining a robust, viable, and environmentally sustainable AF technology for FW valorization. The findings align with global objectives for sustainable process and support the transition towards renewable bio-based chemical production within the framework of the circular economy.
YR 2024
FD 2024
LK https://uvadoc.uva.es/handle/10324/76328
UL https://uvadoc.uva.es/handle/10324/76328
LA eng
NO Escuela de Doctorado
DS UVaDOC
RD 26-jul-2025