Treatment of oily wastewater by ultrafiltration: The effect of different operating and solution conditions

In many industries, such as petroleum production, and the petrochemical, metal, food and cosmetics industries, wastewaters containing an emulsion of oil in water are often produced. The emulsions consist of water (up to 90%), oils (mineral, animal, vegetable and synthetic), surfactants and other contaminates. In view of its toxic nature and its deleterious effects on the surrounding environment (soil, water) such wastewater needs to be treated before release into natural water ways. Membrane-based processes have successfully been applied in industrial applications and are considered as possible candidates for the treatment of oily wastewaters. Easy operation, lower cost, and in some cases, the ability to reduce contaminants below existing pollution limits are the main advantages of these systems. The main drawback of membranes is flux decline due tofouling and concentration polarisation. The complexity of oil-containing systems demands complementary studies on issues related to the mitigation of fouling and concentration polarisation in membranebased ultrafiltration. In this thesis the effect of different operating conditions (factors) on ultrafiltration of oily water is studied. Important factors are normally correlated and, therefore, their effect should be studied simultaneously. This work uses a novel approach to study different operating conditions, like pressure, flow velocity, and temperature, and solution properties, like oil concentration (cutting oil, diesel, kerosene), pH, and salt concentration (CaCl2 and NaCl)) in the ultrafiltration of oily water, simultaneously and in a systematic way using an experimental design approach. A hypothesis is developed to describe the interaction between the oil drops, salt and the membrane surface. The optimum conditions for ultrafiltration and the contribution of each factor in the ultrafiltration of oily water are evaluated. It is found that the effect on permeate flux of the various factors studied strongly depended on the type of oil, the type of membrane and the amount of salts. The thesis demonstrates that a system containing oil is very complex, and that fouling and flux decline can be observed even at very low pressures. This means that only the weak form of the critical flux exists for such systems. The cleaning of the fouled membranes and the influence of different parameters (flow velocity, temperature, time, pressure, and chemical concentration (SDS, NaOH)) were evaluated in this study. It was observed that fouling, and consequently cleaning, behaved differently for the studied membranes. Of the membranes studied, the membrane with the lowest propensity for fouling and the most easily cleaned was the regenerated cellulose membrane (C100H). In order to get more information about the interaction between the membrane and the components of the emulsion, a streaming potential study was performed on the membrane. The experiments were carried out at different pH and oil concentration. It was seen that oily water changed the surface charge of the membrane significantly. The surface charge and the streaming potential during different stages of filtration were measured and analysed being a new method for fouling of oil in this thesis. The surface charge varied in different stages of filtration. It was found that the surface charge of a cleaned membrane was not the same as initially; however, the permeability was equal to that of a virgin membrane. The effect of filtration mode was studied by performing the filtration in both cross-flow and deadend mode. The effect of salt on performance was considered in both studies. It was found that salt decreased the permeate flux even at low concentration. To test the effect of hydrophilicity change, the commercial membranes used in this thesis were modified by grafting (PNIPAAm) on their surfaces. A new technique (corona treatment) was used for this modification. The effect of modification on permeate flux and retention was evaluated. The modified membranes changed their pore size around 33oC resulting in different retention and permeability. The obtained results in this thesis can be applied to optimise the operation of a membrane plant under normal or shock conditions or to modify the process such that it becomes more efficient or effective.

The influence of crystallization conditions on the filtration characteristics of sulphathiazole suspensions

Cooling crystallization is one of the most important purification and separation techniques in the chemical and pharmaceutical industry. The product of the cooling crystallization process is always a suspension that contains both the mother liquor and the product crystals, and therefore the first process step following crystallization is usually solid-liquid separation. The properties of the produced crystals, such as their size and shape, can be affected by modifying the conditions during the crystallization process. The filtration characteristics of solid/liquid suspensions, on the other hand, are strongly influenced by the particle properties, as well as the properties of the liquid phase. It is thus obvious that the effect of the changes made to the crystallization parameters can also be seen in the course of the filtration process. Although the relationship between crystallization and filtration is widely recognized, the number of publications where these unit operations have been considered in the same context seems to be surprisingly small. This thesis explores the influence of different crystallization parameters in an unseeded batch cooling crystallization process on the external appearance of the product crystals and on the pressure filtration characteristics of the obtained product suspensions. Crystallization experiments are performed by crystallizing sulphathiazole (C9H9N3O2S2), which is a wellknown antibiotic agent, from different mixtures of water and n-propanol in an unseeded batch crystallizer. The different crystallization parameters that are studied are the composition of the solvent, the cooling rate during the crystallization experiments carried out by using a constant cooling rate throughout the whole batch, the cooling profile, as well as the mixing intensity during the batch. The obtained crystals are characterized by using an automated image analyzer and the crystals are separated from the solvent through constant pressure batch filtration experiments. Separation characteristics of the suspensions are described by means of average specific cake resistance and average filter cake porosity, and the compressibilities of the cakes are also determined. The results show that fairly large differences can be observed between the size and shape of the crystals, and it is also shown experimentally that the changes in the crystal size and shape have a direct impact on the pressure filtration characteristics of the crystal suspensions. The experimental results are utilized to create a procedure that can be used for estimating the filtration characteristics of solid-liquid suspensions according to the particle size and shape data obtained by image analysis. Multilinear partial least squares regression (N-PLS) models are created between the filtration parameters and the particle size and shape data, and the results presented in this thesis show that relatively obvious correlations can be detected with the obtained models.

Conditions for EFL learning and professional development : Finland-Swedish learner and teacher perspectives

Engelskans dominerande roll som internationellt språk och andra globaliseringstrender påverkar också Svenskfinland. Dessa trender påverkar i sin tur förutsättningarna för lärande och undervisning i engelska som främmande språk, det vill säga undervisningsmålen, de förväntade elev- och lärarroller, materialens ändamålsenlighet, lärares och elevers initiala erfarenheter av engelska och engelskspråkiga länder. Denna studie undersöker förutsättningarna för lärande och professionell utveckling i det svenskspråkiga nybörjarklassrummet i engelska som främmande språk. Utgångsläget för 351 nybörjare i engelska som främmande språk och 19 av deras lärare beskrivs och analyseras. Resultaten tyder på att engelska håller på att bli ett andraspråk snarare än ett traditionellt främmande språk för många unga elever. Dessa elever har också goda förutsättningar att lära sig engelska utanför skolan. Sådan var dock inte situationen för alla elever, vilket tyder på att det finns en anmärkningsvärd heterogenitet och även regional variation i det finlandssvenska klassrummet i engelska som främmande språk. Lärarresultaten tyder på att vissa lärare har klarat av att på ett konstruktivt sätt att tackla de förutsättningar de möter. Andra lärare uttrycker frustration över sin arbetssituation, läroplanen, undervisningsmaterialen och andra aktörer som kommer är av betydelse för skolmiljön. Studien påvisar att förutsättningarna för lärande och undervisning i engelska som främmande språk varierar i Svenskfinland. För att stöda elevers och lärares utveckling föreslås att dialogen mellan aktörer på olika nivå i samhället bör förbättras och systematiseras.

Conditions for different autonomy regimes in the world : a fuzzy-set application

Avhandlingen behandlar temat territoriell autonomi ur ett globalt perspektiv. Syftet är dels att kartlägga de territoriella autonomierna i världen och dels att visa hur en ny metod som fuzzy-set kan användas inom ämnesområdet jämförande politik. Forskningsproblemet är att försöka finna de bakgrundsfaktorer som förklarar uppkomsten av territoriell autonomi som sådant. Territoriella autonomier ses som särlösningar inom stater. Dessa regioner har erhållit en specialställning i förhållande till andra regioner inom respektive stat och även i förhållande till centralmakten i övrigt. Regionerna kan därför ses som undantag inom det enhetliga federala, regionala eller decentraliserade systemet inom en viss stat ifråga. En kartläggning visar att det finns 65 specialregioner fördelade på 25 stater i världen. De flesta av dessa utgörs av öar. Resultaten visar att det finns två vägar vilka leder till territoriell autonomi i allmänhet. Den ena vägen är en kombination av etnisk särprägel och liten befolkningsmängd, medan den andra vägen utgörs av kombinationen av historiska orsaker och geografiskt avstånd. Båda vägar är lika giltiga och förutsättningen är en demokratisk miljö.

Motivational Influences on Transfer: Dimensions and Boundary Conditions

The focus of this dissertation is the motivational influences on transfer in higher education and professional training contexts. To estimate these motivational influences, the dissertation includes seven individual studies that are structured in two parts. Part I, Dimensions, aims at identifying the dimensionality of motivation to transfer and its structural relations with training-related antecedents and outcomes. Part II, Boundary Conditions, aims at testing the predictive validity of motivation theories used in contemporary training research under different study conditions. Data in this dissertation was gathered from multi-item questionnaires, which were analyzed differently in Part I and Part II. Studies in Part I employed exploratory and confirmatory factor analysis, structural equation modeling, partial least squares (PLS) path modeling, and mediation analysis. Studies in Part II used artifact distribution meta-analysis, (nested) subgroup analysis, and weighted least squares (WLS) multiple regression. Results demonstrate that motivation to transfer can be conceptualized as a three-dimensional construct, including autonomous motivation to transfer, controlled motivation to transfer, and intention to transfer, given a theoretical framework informed by expectancy theory, self-determination theory, and the theory of planned behavior. Results also demonstrate that a range of boundary conditions moderates motivational influences on transfer. To test the predictive validity of expectancy theory, social cognitive theory, and the theory of goal orientations under different study settings, a total of 17 boundary conditions were meta-analyzed, including age; assessment criterion; assessment source; attendance policy; collaboration among trainees; computer support; instruction; instrument used to measure motivation; level of education; publication type; social training context; SS/SMC bias; study setting; survey modality; type of knowledge being trained; use of a control group; and work context. Together, the findings cumulated in this thesis support the basic premise that motivation is centrally important for transfer, but that motivational influences need to be understood from a more differentiated perspective than commonly found in the literature, in order to account for several dimensions and boundary conditions. The results of this dissertation across the seven individual studies are reflected in terms of their implications for theory development and their significance for training evaluation and the design of training environments. Limitations and directions to take in future research are discussed.

Modeling study of limestone reactions in fluidized bed conditions

Traditionally limestone has been used for the flue gas desulfurization in fluidized bed combustion. Recently, several studies have been carried out to examine the use of limestone in applications which enable the removal of carbon dioxide from the combustion gases, such as calcium looping technology and oxy-fuel combustion. In these processes interlinked limestone reactions occur but the reaction mechanisms and kinetics are not yet fully understood. To examine these phenomena, analytical and numerical models have been created. In this work, the limestone reactions were studied with aid of one-dimensional numerical particle model. The model describes a single limestone particle in the process as a function of time, the progress of the reactions and the mass and energy transfer in the particle. The model-based results were compared with experimental laboratory scale BFB results. It was observed that by increasing the temperature from 850 °C to 950 °C the calcination was enhanced but the sulfate conversion was no more improved. A higher sulfur dioxide concentration accelerated the sulfation reaction and based on the modeling, the sulfation is first order with respect to SO2. The reaction order of O2 seems to become zero at high oxygen concentrations.

Organizational mechanisms and conditions of individuals for knowledge sharing in post-acquisition integration

The challenges of knowledge sharing after cross-border acquisitions are widely recognised. The study took a new view to the subject by applying a two-level framework provided by the knowledge governance approach. The purpose of the study was to investigate the effects of organizational mechanisms on the conditions of individuals for knowledge sharing in post-acquisition integration context. Qualitative research methods were used in this case study. Individual interviews were performed within an international firm after a recent cross-border acquisition. The results showed that integrators, the rotation of the personnel from the acquiring firm and visits and meetings enhance the conditions at the individual level for knowledge sharing after the acquisition. Respectively, strategic change, matrix structure and foreign HRM practices challenge the conditions at the individual level for knowledge sharing in the early post-acquisition integration phase. The findings are supported by the prior research on knowledge management in acquisitions. In particular, the study enlightens how organizational level actions influence the conditions of individuals for knowledge sharing. The study suggests that organizations should adjust organizational mechanisms to support the conditions of individuals, in order to promote knowledge sharing in the early phase of the integration.

Searchig the links between "knowledge governance mechanisms", "the individual conditions of knowledge sharing", and "individual's knowledge sharing behaviour".

The objective of this study was to understand how organizational knowledge governance mechanisms affect individual motivation, opportunity, and the ability to share knowledge (MOA framework), and further, how individual knowledge-sharing conditions affect actual knowledge sharing behaviour. The study followed the knowledge governance approach and a micro-foundations perspective to develop a theoretical model and hypotheses, which could explain the casual relationships between knowledge governance mechanisms, individual knowledge sharing conditions, and individual knowledge sharing behaviour. The quantitative research strategy and multivariate data analysis techniques (SEM) were used in the hypotheses testing with a survey dataset of 256 employees from eleven military schools of Finnish Defence Forces (FDF). The results showed that “performance-based feedback and rewards” affects employee’s “intrinsic motivation towards knowledge sharing”, that “lateral coordination” affects employee’s “knowledge self-efficacy”, and that ”training and development” is positively related to “time availability” for knowledge sharing but affects negatively employee’s knowledge self-efficacy. Individual motivation and knowledge self-efficacy towards knowledge sharing affected knowledge sharing behaviour when work-related knowledge was shared 1) between employees in a department and 2) between employees in different departments, however these factors did not play a crucial role in subordinate–superior knowledge sharing. The findings suggest that individual motivation, opportunity, and the ability towards knowledge sharing affects individual knowledge sharing behaviour differently in different knowledge sharing situations. Furthermore, knowledge governance mechanisms can be used to manage individual-level knowledge sharing conditions and individual knowledge sharing behaviour but their affect also vary in different knowledge sharing situations.

Effect of additives, precursors and process conditions on particle morphology

The objective of the thesis was to develop methods to manufacture and control calcium carbonate crystal nucleation and growth in precipitation process. The work consists of experimental part and literature part that addresses theory of nucleation, crystallization and precipitation. In the experimental part calcium carbonate was precipitated using carbonization reaction. Precipitation was carried out in presence of known morphology controlling agents (anionic polymers and sodium silicate) and by using different operation conditions. Formed material was characterized using SEM images, and its thermal stability was assessed. This work demonstrates that carbon dioxide feeding rate and concentrations of calcium hydroxide and additives can be used to control size, shape and amount of precipitating calcium carbonate.