102 research outputs found
Engineering zeolite pellets for the adsorption of organic micropollutants
No full textOur use of pharmaceuticals, pesticides and personal care products leads to an increase of organic micropollutants (OMPs) into the aquatic environment. Conventional wastewater treatment plants are not designed for the removal of OMPs and need to be upgraded to reduce OMP contamination. The adsorption of OMPs to zeolites is proposed as an alternative treatment method. Zeolites are synthesized as powders, however they need to be shaped into pellets to be used in water treatment practice. This research focussed on engineering zeolite pellets and which properties of these pellets are important for the adsorption of OMPs. First the influence of the calcination temperature and binder content on the mechanical stability and porosity of the pellets was analysed. Second, the influence of two different preparation techniques (extrusion and high-shear granulation) and the introduction of a polymer on the mechanical stability, porosity and adsorption kinetics of the pellets was assessed. Third, the effect of the porosity on the breakthrough for an empty bed contact time (EBCT) of 20, 5 and 1 minute(s) was determined according to the linear driving force (LDF) model. It was found that an increasing binder content and calcination temperature increased the wear resistance and porosity of the pellets. However, the effect on the porosity is minimal. The introduction of the polymer had opposite effect on extruded and granulated pellets. For extruded pellets, the introduction of the polymer increased the porosity. However, the granulated pellets showed a decrease in porosity. A relation was found between the porosity and the wear resistance and between the porosity and adsorption kinetics. A larger porosity decreased the wear resistance of the pellets and increased the kinetic rate constant. The porosity was of great importance in relation to the breakthrough. First, the porosity in the zeolite pellets determined to a great extent the bulk density of the filter bed. A higher bulk density resulted in a later breakthrough point. The bulk density was also influenced by the shape of the pellet. Spherically-shaped (granulated) pellets had a higher bulk density than rod-shaped (extruded) pellets. Second, the porosity was related to the kinetic rate constant. At lower EBCTs (5 and 1 minute), the kinetic rate constant had an influence on the breakthrough point. For these EBCTs, a higher kinetic rate constant led to a later breakthrough point. It was recommended to optimize the zeolite pellets by making the extruded pellets in a more spherically-shaped form and to start column experiments to validate the LDF-model
The meaning of activities in the dwelling and residential environment: A structural approach in people-environment relations
No full textReal Estate and HousingOTB Research Institut
Quality of Coated Particles: Physical - Mechanical Characterization of Polymeric Film Coatings
No full textAll coated particle producers, when applying the coating layer(s) would like to know precisely what is the best coating system to use in order to answer customer’s requests. It is, therefore, of very high relevance for many industries, to have a clear understanding of what are the parameters I need to trigger in order to generate the requested quality. Such understanding was the target of this work. The specific equipments designed at Delft University of Technology enabled us to measure the resistance to attrition and the resistance to abrasion of both reference coating agents and commercially pre-mixed coating systems. The resistance to attrition was directly related to the intrinsic properties of the coating material, to the process parameters used to apply the coating layer (fluid bed coating in this case) and to the conditions in which the particles are stored. The viscoelastic properties of the coating layers were measured by using nano indentation. Very good correlation between the viscoelasticity term, tan ?, and the resistance to attrition was found. Cast and sprayed films were produced as representation of the coating film. The morphology and the structure of coating layers were mimicked much better by sprayed films which could be obtained by novel equipment designed during this work. To assess the quality of the coating layer and determine how efficient the coating process was, X-Ray micro tomography in combination with image analysis was used. This gave us a very robust set of data which could be used to correlate the quality of the coating layer to the parameters chosen during coating process and those two with the final performance of the coated particles in respect of resistance to attrition/abrasion. Finally commercially available pre-mixed coating systems were used as case study. By comparing them with the reference coating agents we could proof and quantify how important are the additives, plasticisers in primis, in increasing the coating quality and, therefore, the resistance to mechanical stresses.Chemical Engineering, ChemEApplied Science
Benaderingsmethode voor het overgangsmoment van doorgaande liggers met vele velden
No full textAnalytisch wordt ingegaan op het door R. Filarski in "Invloedsvlakken voor de berekening van buigende momenten in de dekplaat van een orthotrope plaatconstructie" (Heron 14, no. 1) gestelde omtrent de benadering van het overgangsmoment van doorgaande liggers door het gemiddelde te nemen van het overgangsmoment van een ligger op 3 steunpunten met vrije en eenzelfde ligger met volledig ingeklemde uiteinden. Deze analyse bevestigt, dat die methode een voor praktische doeleinden goed bruikbaar hulpmiddel is.Civil Engineering and Geoscience
Urban living from a resident's perspective: Draft
No full textFor some decades governments in Europe, the US and Australia promote compact city concepts, to achieve more sustainable patterns of travel and reduce energy use. For over 30 years spatial planning policies of the Dutch government are aimed at implementing compact urbanization in various forms. In contrast to the promoted high density urban living by the government, consumers ask for more spacious, green residential environments. This obviously leads to a tension between governmental policy and consumers’ housing preferences. This paper is written from a resident’s perspective. It aims at providing a deeper understanding of why people prefer to live in a city centre, suburban or rural type of residential environment. This might show how possible trade-offs between urban (high density) living and more spacious, green living could be made. A survey among 659 people living in the Netherlands reveals that people prefer to live in a city centre for the accessibility of its amenities. People who would prefer to live in a rural area mentioned many diverse reasons, varying from peace and quiet to the character of the residential environment, social contacts and tradition. People who prefer a suburban type of residential environment want both proximity to city centre amenities and a quiet residential environment. Remarkably, the data show also many similarities in the use and meanings of city centre, suburban and rural types of residential environment. For example, for all people the residential environment should be a place where they can relax, forget about their work and enjoy life. Taking into account the differences and similarities in the use and meaning of the three types of residential environment, one might argue that on the one hand access to amenities and on the other hand a quiet, green residential environment are the crucial trade-offs from a resident’s perspective.Urban and Mobility StudiesOTB Research Institut
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