Titel Deelnemers "Ultrasonication affects the bio-accessibility of primary dairy cow manure digestate for secondary post-digestion" "Matthijs Somers, Lise Appels" "The role of digestate disintegration in anaerobic digestion" "Matthijs Somers" "Anaerobic digestion is a biological process that converts organic wastes into energy rich biogas and nutrient rich digestate. The produced biogas can be valorised on site as electricity and heat, or it can be upgraded into methane and used in existing methane grids or used as transportation fuel. The hydrolysis step is generally regarded as the rate-limiting step of anaerobic digestion. In this research, the effect digestate disintegration methods on the biochemical characteristics of dairy manure digestate was investigated. In this scope, hydrogen peroxide, ozone and ultrasound disintegration techniques were used. Among the tested methods, ultrasound disintegration increased the soluble fraction of the digestate and slightly increased the bioaccessibility of the solid fraction which increased the methane production. This positive effect is related to the digestate age and the specific ultrasonic energy. The overall results of this thesis are expected to increase the application potential of digestate disintegration." "Stripping and scrubbing of ammonium using common fractionating columns to prove ammonium inhibition during anaerobic digestion" "Karel Ghyselbrecht, Annick Monballiu, Matthijs Somers, Lise Appels, Boudewijn Meesschaert" "Anaerobic digestion to produce biogas is generally considered as one of the most sustainable technologies for the production of renewable energy. During this microbial process, organically bound nitrogen is released as ammonium that ends up in the digestate and fnally may inhibit the process. In this study, it is investigated if ammonium can be removed and recovered out of the liquid fraction of a thermophilic digestate from a potato processor. This is achieved at laboratory scale through an easy and self-designed stripping and scrubbing process using Vigreux and Dufton columns, which are commonly used laboratory fractionating columns. The stripping is performed at pH 8.5 and at 323.15 K (50 °C), which results in the volatilization of the ammonium present in ammonia. Subsequently, the stripping gas charged with ammonia is put into contact with a sulphuric acid solution, resulting in (NH4)2SO4, which can be used as an N–S fertilizer. In addition, the digestion experiments have demonstrated that the biogas yield is 36% higher after removal of the ammonium from the digestate compared to the untreated digestate." "Optimization of hydrothermal conversion of bamboo (Phyllostachysaureosulcata) to levulinic acid via response surface methodology" "Nick Sweygers, Matthijs Somers, Lise Appels" "In this study, the dilute acid hydrolysis of lignocellulosic bamboo (Phyllostachys aureosulcata) particles to levulinic acid in a hydrothermal synthesis reactor is reported. The aim of the study was to optimize the reaction conditions for maximum levulinic acid production in terms of reaction time (t), reaction temperature (T) and HCl concentration (cHCl) via Response Surface Methodology (RSM). A maximum levulinic acid yield of 9.46 w% was predicted at the following reaction conditions: t of 3 h, T of 160 °C and cHCl of 0.37 M. A maximal experimental yield of levulinic acid of 10.13 w% was observed, which in respect to the cellulose fraction of the bamboo particles corresponds to 34.60 w% or 48.05 mol%. Furfural, which is formed by the hemicellulose fraction of bamboo, has not been observed within the boundaries of the RSM model, since it is already degraded under the given reaction conditions. The conversion of levulinic acid and furfural occurred more or less simultaneously, however, furfural was more vulnerable to degradation reactions at the given process conditions. Therefore, if both fractions (cellulose + hemicellulose) are required to be valorized, further optimization is required. However, the global results of this study provide insight in the potential of lignocellulosic bamboo as an alternative platform to fossil sources." "The issues of nitrogenous components during anaerobic digestion" "Karel Ghyselbrecht, Annick Monballiu, Matthijs Somers, Lise Appels, Boudewijn Meesschaert"