Reliable information about the micro-processes during filtration and dewatering of filter cakes allows more accurate statements about process development and design in any industrial application with solid-liquid separation units. Distributed particle properties such as shape, size, and material influence the formation of the porous network structure, which can show considerable local fluctuations in vertical and horizontal alignment in the cake forming apparatus. The present work relates to a wide range of particle sizes and particle shapes and presents their effects on integral, but preferably local, structural parameters of cake filtration. Current models for the relationship between particle properties and resulting porous structure remain inaccurate. Therefore, the central question focus on the model-based correlation between obtained tomographic 3D information and characteristic cake and process parameters. In combination with X-ray computed tomography and microscopy (ZEISS Xradia 510), data acquisition of the structural build-up of filter cakes is possible on a small scale (filter area 0.2 cm²) and a conventional laboratory scale (filter area 20 cm², VDI 2762 pressure nutsch). Thereby, the work focuses on structural parameters at the local level before, during, and after cake dewatering, such as porosity, coordination number, three-phase contact angle, characteristics of pores and isolated liquid regions, the liquid load of individual particles, tortuosity, and capillary length, and the corresponding spatial distributions. Seven different particle systems in the range of 20 and 500 µm, suspended in aqueous solutions with additives for contrast enhancement, served as raw materials for the filter cake formation. Image data processing from 16-bit greyscale images with a resolution of 2 to 4 µm/voxel edge length includes various operations with a two-stage segmentation to identify air, solid particles, and liquid phase, resulting in a machine learning-based automated approach. Subsequent modeling and correlation of measured parameters rely on experimentally verified quantities from mercury porosimetry, laser diffraction, dynamic image analysis, static and dynamic droplet contour analysis, as well as filtration and capillary pressure tests according to VDI guidelines. The tomography measurements provide microscopic information about the porous system, quantified using characteristic key parameters and distribution functions. By studying the cake structure concerning the local distribution of particle size and shape and the resulting porosity, segregation effects can be avoided by increasing the feed concentration of particles, whereby swarm inhibition of particles in the initial suspension strongly hinders or completely suppresses layer formation in the cake according to distributed particle properties (Publication A). In the subsequent dewatering of the filter cake to the irreducible saturation, the measurement of the local coordination number as well as the remaining liquid volumes at the particle contacts allows the determination of a discrete liquid load distribution by correlation with the respective particle volume (Publication B). The determination of the capillary length - shortest capillary for single-phase pore flow and capillary of least resistance for multiphase pore flow - provides modeling approaches for the cake formation from publication A as well as the dewatering process from publication B (Publication C). The parameter sets obtained also help to transfer and extend existing, theoretical models of multiphase pore flow to the application example of filter cake dewatering (Publication D). At the microscopic level, the measurement of the three-phase contact angle at isolated liquid volumes within the porous matrix provides a deeper understanding of the macroscopic models from publications C and D (Publication E).:List of Figures List of Tables Notation 1 Introduction 2 Multiphase Processes in Porous Media 2.1 Cake Filtration and Single Phase Porous Media Flow 2.2 Cake Dewatering 2.2.1 Particle Surface Wettability 2.2.2 Capillarity in Porous Media 2.2.3 Static Capillary Pressure 2.2.4 Dynamic Capillary Pressure 3 Acquisition of 3D Information of Porous Media 3.1 Absorption and Scattering of X-rays 3.2 X-ray Microscopy 3.2.1 Image Acquisition 3.2.2 Image Reconstruction 3.2.3 Image Quality and Artifacts 3.3 Image Post-Processing 3.3.1 Image Enhancement 3.3.2 Segmentation and Thresholding 3.3.3 Processing Binary Images 3.4 Image Measurement 4 Materials and Methods 4.1 The Solid Phase 4.2 The Liquid Phase 4.3 Suspension Stability 4.4 Experimental Design and Down-Scale for Tomography Measurements 4.5 Experimental Characterization of Filtration and Dewatering Properties 4.5.1 Cake Filtration 4.5.2 Cake Dewatering (Capillary Pressure Measurements) 5 Conclusion and Outlook Literature Publications A to E Appendix

[pt] A microtomografia computadorizada de uma amostra de rocha possibilita uma caracterização do meio poroso e pode ser utilizada para estimar propriedades da rocha em macroescala, isto é, em escala de reservatório. Métodos baseados em mapas de distâncias e em algoritmos de erosão são as principais abordagens utilizadas para extração de uma rede de poros e gargantas a partir de imagens microtomográficas de rocha. Este trabalho propõe um método híbrido para a construção da rede, de modo que, durante o processo de modelagem na escala de poros, obtemos um esqueleto do espaço poroso por meio de um algoritmo de erosão e utilizamos um mapa de distâncias para construir uma rede de poros e gargantas. A determinação dos poros e gargantas a partir do esqueleto adota uma abordagem não-determinística possibilitando a geração de múltiplas redes com configurações distintas a partir de um mesmo esqueleto. Avaliamos a variabilidade dos cenários gerados e comparamos as estimativas para as propriedades petrofísicas com as obtidas pelo método de Bolas Máximas por meio dos resultados de uma simulação de fluxo monofásica na rede. / [en] Computerized microtomography of a rock sample enables a characterization of the porous medium and can be used to estimate rock properties at the macro-scale, i.e., reservoir-scale. Methods based on distance maps and thinning algorithms are the main approaches used for extracting a pore and throats network from microtomographic rock images. This paper proposes a hybrid method for constructing the network. So that during the pore-scale modeling process, we obtain a skeleton of the pore space by using a thinning algorithm and a distance map to build a network of pores and throats. The determination of pores and throats from the skeleton assumes a non-deterministic approach enabling the generation of multiple networks with distinct configurations from the same skeleton. We evaluate the variability of the generated scenarios and compare the estimates for the petrophysical properties with those obtained by the Maximum Ball Method through the results of a single-phase flow simulation on the network.