Abstract The filtration of pulp suspension is one of the key papermaking processes. It is measured using many kinds of analyzers and modeled using both physical and empirical mathematical expressions. The main target of this thesis was to develop an empirical mathematical model to describe the filtration of a drainage analyzer. In this work the diameter of the screen (10 cm), as well as the amount (1000 cm3), consistency (0.3%) and temperature (20 ˚C) of the sample were (about) the same as those of the Canadian Standard Freeness analyzer. The analyzer was equipped with the measurements of filtrated volume, driving pressure and filtrate consistency. The pressures from the underpressure of 80 kPa to the overpressure of 80 kPa could be used. Pulp types of SGW, PGW, TMP and chemical pulp with freeness levels from 30 to 600 ml were analyzed. A conditioner of the sample volume, temperature and consistency measurements was constructed. The error of freeness value caused by the errors of the conditioner was evaluated to be less than 1%. The equations for the calculation of the possible initial values of the controlled quantities were derived. The optically measured consistencies of the filtrates were different for different pulp types and decreased close to zero before the filtrated volume of 150 cm3. The filtration seemed to change the portion of optically active fines. In the model of this work the filtration time (t) is proportional to an experimental power of the filtrated volume (V): Ve = kt. An auxiliary constant (Ve = kt + V0e) was used during the regression analyses to overcome the disturbances and non-validity of the model in the beginning of the filtration. The correlation coefficients of the fit were higher than 0.999. The exponent 2 suggested by Darcy’s law is a special case while the exponent has also been close to 1 or 3. The curves of specific filtration resistances, based on the model and pressure measurements, were shown to change during the course of drainage and as a function of pressure additionally dependent on the pulp type. The model was successfully used to calculate freeness values and to filter noise from the measurements. / Tiivistelmä Paperimassasulpun suotauttaminen on paperinvalmistuksen avainprosesseja. Sitä on mitattu monenlaisilla analysaattoreilla ja kuvattu sekä fysikaalisilla että kokeellisilla matemaattisilla malleilla. Tämän tutkimuksen päätavoite on kehittää suotautuvuusanalysaattorin kokeellista matemaattista mallia. Tutkimuksessa viiran halkaisija (10 cm) sekä näytteen määrä (1000 cm3), sakeus (0.3 %) ja lämpötila (20 ˚C) olivat suunnilleen samat kuin Canadian standard freeness –analysaattorissa. Järjestelmä mittasi suotautettua tilavuutta, suotauttavaa painetta ja suodoksen sakeutta. Suotautuspaineet olivat 80 kPa:n ali- ja ylipaineen väliltä. Testattavana oli hioketta, painehioketta ja termohierrettä sekä kemiallista massaa, joiden freeness oli 30 ml:sta 600 ml:aan. Analysaattoriin rakennettu vakiointijärjestelmä sääti näytteen sakeuden, tilavuuden ja lämpötilan niin tarkasti halutuiksi, että näiden vaihtelu ei olisi muuttanut freeness-arvoa edes prosenttia. Suureiden kehittymiselle johdettiin kaavat. Niiden avulla voidaan laskea ne näytteen arvoalueet, joilta halutut tavoitearvot voidaan saavuttaa. Optisesti mitattu suodoksen sakeus riippui massatyypistä ja hiipui lähes nollaksi ennen kuin 150 ml oli suotautettu. Suotautus muutti optisesti aktiivisen hienoaineen osuutta. Tämän työn suodoskäyrän mallissa aika (t) on verrannollinen suotautetun tilavuuden (V) kokeellisen potenssiin: Ve = kt. Mallinnuksen ajaksi lisätään apuparametri (Ve = kt+V0e), jotta suotautuksen alku ei huononna mallia. Sovituksen korrelaatiokerroin oli yli 0.999. Eksponentin arvo vaihteli vähän yli yhdestä melkein kolmeen, joten Darcyn lain mukainen eksponentin arvo 2 osoittautui erikoistapaukseksi. Mallin ja painemittauksen avulla lasketut ominaisresistanssit muuttuivat suotautuksen kuluessa ja riippuivat myös massatyypistä. Mallin avulla voitiin laskea näytteen freeness sekä suodattaa mittauskohinaa.

The target of the first part of this diploma thesis is focused on the problems relating to the sludge production from the wastewater treatment plant and subsequent sludge treatment. Wastewater treatment plant and individual processes from the sludge management are described. The process of the sludge dewatering is described more extensively. Various methods of the dewatering and materials balance are described, too. The second part of this thesis is based on the experiment which took place on wastewater treatment plant Tetčice. The influence of the polymeric organic flocculant dosing on the sludge dewatering was monitored by this experiment. Dependence of the sludge dry matter and filtrate suspended solids content on the specific amount of flocculant was evaluated from experiment’s outputs. Using materials balance and outputs of the experiment, economical balance was made. It made possible to choose the most economic and technologically optimal way of the sludge dewatering on wastewater treatment plant Tetčice.

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

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В работе рассматриваются проблемы размещения и обработки образующегося осадка на предприятиях водоподготовки. Проведен анализ деятельности предприятий водоподготовки как объекта негативного воздействия на окружающую среду в России и Свердловской области. В настоящее время на большинстве водопроводных станций не организовано повторное использование промывных вод и применение технологий обезвоживания осадка. Сброс таких вод приводит к загрязнению источников водоснабжения. Проблема обработки водопроводного осадка справедливо считается одной из наименее разработанных, наиболее технически сложной и дорогостоящей. В работе проведено сравнение существующих технологий обезвоживания осадка. Предложен инвестиционный проект по разработке и внедрению эффективной системы обезвоживания осадка в условиях уменьшения экологической нагрузки путем исключения сброса промывных вод в окружающую среду. Приводится технико-экономическое обоснование проекта и рассчитана его эколого-экономическая эффективность. / The paper deals with the problems of placing and processing the formed sludge at water treatment plants. The analysis of water treatment enterprises as an object of negative impact on the environment in Russia and the Sverdlovsk region has been carried out. Currently, most waterworks do not organize reuse of washing water and the use of sludge dewatering technologies. Discharge of such water leads to contamination of water supply sources. The problem of treatment of a water sediment is rightly considered one of the least developed, the most technically complex and costly. The paper compares existing sludge dewatering technologies. An investment project is proposed to develop and implement an effective sludge dewatering system in conditions of decreasing the ecological load by eliminating the discharge of wash water into the environment. The feasibility study of the project is given and its ecological and economic efficiency is calculated.

In 2011 the mining industry purchased 14.5% of the electrical energy generated by Eskom. During 2011 in South Africa, dewatering pump systems on gold mines were the fourth largest electrical energy consumer on South African mines therefor making dewatering pumps ideal candidates to generate significant financial savings. These savings can be realised by controlling time-of-use (TOU) schedules. Previous studies concentrated on the impact of improving a pumping scheme of a single mineshaft. This dissertation will focus on the operations of a complete dewatering system consisting of multiple mineshafts. The case study will consist of a gold mine complex comprising of five different shafts - each with its own reticulation system – as well as the larger interconnected water reticulation system. Various pumping options were investigated, simulated and verified. The interaction between shafts was determined when load-shifting was scheduled for all the shafts taking each shaft’s particular infrastructure into account. The underground dewatering system was automated and optimised based on the simulation results. Mine safety protocols were adhered to while optimal pump operational schedules were introduced. / Thesis (MIng (Electrical and Electronic Engineering))--North-West University, Potchefstroom Campus, 2013.

In 2011 the mining industry purchased 14.5% of the electrical energy generated by Eskom. During 2011 in South Africa, dewatering pump systems on gold mines were the fourth largest electrical energy consumer on South African mines therefor making dewatering pumps ideal candidates to generate significant financial savings. These savings can be realised by controlling time-of-use (TOU) schedules. Previous studies concentrated on the impact of improving a pumping scheme of a single mineshaft. This dissertation will focus on the operations of a complete dewatering system consisting of multiple mineshafts. The case study will consist of a gold mine complex comprising of five different shafts - each with its own reticulation system – as well as the larger interconnected water reticulation system. Various pumping options were investigated, simulated and verified. The interaction between shafts was determined when load-shifting was scheduled for all the shafts taking each shaft’s particular infrastructure into account. The underground dewatering system was automated and optimised based on the simulation results. Mine safety protocols were adhered to while optimal pump operational schedules were introduced. / Thesis (MIng (Electrical and Electronic Engineering))--North-West University, Potchefstroom Campus, 2013.

The provision of clean drinking water typically involves treatment processes to remove contaminants. The conventional process involves coagulation with hydrolysing metal salts, typically of aluminium (‘alum’) or trivalent iron (‘ferric’). Along with the product water this also produces a waste by-product, or sludge. The fact of increasing sludge production — due to higher levels of treatment and greater volume of water supply — conflicts with modern demands for environmental best practice, leading to higher financial costs. A further issue is the significant quantity of water that is held up in the sludge, and wasted. / One means of dealing with these problems is to dewater the sludge further. This reduces the volume of waste to be disposed of. The consistency is also improved (e.g. for the purpose of landfilling). And a significant amount of water can be recovered. The efficiency, and efficacy, of this process depends on the dewaterability of the sludge.In fact, good dewaterability is vital to the operation of conventional drinking water treatment plants (WTP’s). The usual process of separating the particulates, formed from a blend of contaminants and coagulated precipitate, relies on ‘clarification’ and ‘thickening’, which are essentially settling operations of solid–liquid separation.WTP operators — and researchers — do attempt to measure sludge dewaterability, but usually rely on empirical characterisation techniques that do not tell the full story and can even mislead. Understanding of the physical and chemical nature of the sludge is also surprisingly rudimentary, considering the long history of these processes. / The present work begins by reviewing the current state of knowledge on raw water and sludge composition, with special focus on solid aluminium and iron phases and on fractal aggregate structure. Next the theory of dewatering is examined, with the adopted phenomenological theory contrasted with empirical techniques and other theories.The foundation for subsequent analyses is laid by experimental work which establishes the solid phase density of WTP sludges. Additionally, alum sludges are found to contain pseudoböhmite, while 2-line ferrihydrite and goethite are identified in ferric sludges. / A key hypothesis is that dewaterability is partly determined by the treatment conditions. To investigate this, numerous WTP sludges were studied that had been generated under diverse conditions: some plant samples were obtained, and the remainder were generated in the laboratory (results were consistent). Dewaterability was characterised for each sludge in concentration ranges relevant to settling, centrifugation and filtration using models developed by LANDMAN and WHITE inter alia; it is expressed in terms of both equilibrium and kinetic parameters, py(φ) and R(φ) respectively.This work confirmed that dewaterability is significantly influenced by treatment conditions.The strongest correlations were observed when varying coagulation pH and coagulant dose. At high doses precipitated coagulant controls the sludge behaviour, and dewaterability is poor. Dewaterability deteriorates as pH is increased for high-dose alum sludges; other sludges are less sensitive to pH. These findings can be linked to the faster coagulation dynamics prevailing at high coagulant and alkali dose.Alum and ferric sludges in general had comparable dewaterabilities, and the characteristics of a magnesium sludge were similar too.Small effects on dewaterability were observed in response to variations in raw water organic content and shearing. Polymer flocculation and conditioning appeared mainly to affect dewaterability at low sludge concentrations. Ageing did not produce clear changes in dewaterability.Dense, compact particles are known to dewater better than ‘fluffy’ aggregates or flocs usually encountered in drinking water treatment. This explains the superior dewaterability of a sludge containing powdered activated carbon (PAC). Even greater improvements were observed following a cycle of sludge freezing and thawing for a wide range of WTP sludges. / Further aspects considered in the present work include deviations from simplifying assumptions that are usually made. Specifically: investigation of long-time dewatering behaviour, wall effects, non-isotropic stresses, and reversibility of dewatering (or ‘elasticity’).Several other results and conclusions, of both theoretical and experimental nature, are presented on topics of subsidiary or peripheral interest that are nonetheless important for establishing a reliable basis for research in this area. / This work has proposed links between industrial drinking water coagulation conditions, sludge dewaterability from settling to filtration, and the microstructure of the aggregates making up that sludge. This information can be used when considering the operation or design of a WTP in order to optimise sludge dewaterability, within the constraints of producing drinking water of acceptable quality.

В результате проведенных теоретических и экспериментальных исследований процесса обезвоживания тонкодисперсной суспензии глубоководных органо-минеральных осадков Черного моря в фильтровально-пульсационной машине определены основные ее параметры, а также установлены зависимости этих параметров от показателей процесса фильтрования. Разработаны конструкция фильтровально-пульсационной машины и методика расчета ее параметров применительно к морским органо-минеральным осадкам, а также обоснованы рациональные режимные и конструктивные параметры данной машины. / Die Dissertation begründet die Parameter der pulsierenden Filtermaschine zur Entwässerung feindisperser Suspension, organisch-mineralische Tiefsee-Sedimente aus dem Schwarzen Meer, welche aufgrund der theoretischen und experimentallen Untersuchungen des Filtrationsprozesses beim statischen und pulsierenden Druck, sowie der entwickelten Abhängigkeiten dieser Parameter von Suspensionseigenschaften und Filtrationskennwerten definiert werden können. Es wurde eine neue Konstruktion der pulsierenden Filtermaschine und eine Methodik zur Parameterberechnung in Bezug auf marine Sedimentsuspension entwickelt, sowie die rationellen Betriebs- und Konstruktionsparameter der pulsierenden Filtermaschine definiert. Dabei wurde auch die Effizienz unter Einsatz von pulsierenden im Vergleich zum statischen Druck bei der Sedimententwässerung bewertet.

The subject of the presented thesis is a foundation pit dewatering numerical analysis. The study is introduced with practical examples and the summary of the necessary theory. Individual subtasks are modeled as two or three-dimensional problem on a chosen foundation pit example. A comparison with analytical methods and theoretical knowledge about the problem is made. The studies focus on specifying the pumped water quantity, the shape of the depression curve, determining the size of the numerical model and the influence of the finite element network density. The steady-state flow cases, water table aquifer, a well system, sheet pile wall cutoff effect, surface drained pit and partial penetration cases are analyzed. The work proposes a method of modeling a well by FEM. The main output is a 3D analysis of a submerged excavation dewatered with a partially penetrated well system.