The increasing demand for sand in the construction sector underscores the need for sustainable alternatives to natural sand. This bachelor's thesis explores the application of Fine Recycled Concrete Aggregate (fRCA) produced by Heating air and classification system (HAS) from the Concrete To Cement and Aggregate (C2CA) technology as a sustainable substitute for natural sand. fRCA consists of pure sand and cementitious material, with the removal of extraneous substances such as timber and steel. While fRCA finds applications in various sectors, the challenges in its use in mortar include property variations, cost considerations, and the absence of quality control standards. Addressing these challenges would be crucial for the wider adoption of fRCA in mortar applications. This research aims to characterize fRCA properties, enhance fRCA quality through acid treatment and milling, determine optimal milling parameters, investigate the influence of the water-cement (W/C) ratio on mortar workability, and assess the compressive and tensile strength of mortar with fRCA. The central inquiry pertains to identifying the optimal approach for enhancing fRCA properties and integrating it into concrete mixes for civil engineering applications. The study is exploring the effects of untreated fRCA, milled fRCA, and acid-washed fRCA on mortar properties. It is also determined the ideal quantity of milled fRCA to replace natural sand in mortar mixtures. The theoretical evaluation of sustainability in mortar mixes utilizing this specific fRCA have been conducted. This research did not investigate the chemical properties of fRCA. Notably, the quality of fRCA differs from that of Natural Aggregate (NA), characterized by distinct particle size distributions and water absorption properties. While fRCA can effectively replace NA in mortar mixtures, it does affect compressive strength due to higher water absorption and the partial retention of cementitious material. However, by milling or treating it with ACID, the quality of fRCA can be improved, making it possible to use fRCA as a replacement for NS in mortars. The optimal substitution rate of NA with fRCA is identified as 25%, with the possibility of an increase to 100%, depending on the specific application. The integration of fRCA in concrete holds potential for sustainability by reducing reliance on natural resources and curbing waste generated by the construction industry.

In order to help the building and construction sector move towards a Circular Economy and lower its environmental impact, a better founded choice regarding the design and selection of building materials for a building’s load bearing structure is required. By investigating different design strategies that focus on optimizing various aspects of the Circular Economy, an office building can be designed in such a way that it matches both the initial client’s requirements as well as possibly changing future needs. Different design strategies then lead to varying lay-outs of a building’s load bearing structure and the building material it’s made of.
By ranking ten design perspectives in varying orders, three main design strategies can be formed. The first one maximizes a building's technical service life, thereby limiting the use of new materials and energy during maintenance activities. The second strategy aims for a maximal functional service life, by making the original building fit for possible other functions in the future. The final strategy maximizes a building's residual value, which includes re-use of building elements in new projects.
The next step is to link these design strategies to various criteria that can be included in the Multi Criteria Analysis. This results in a total of nine criteria, some of them being linked to the characteristics of a building material and the type of connections that come with that material. Other criteria depend on the design of a load bearing structure, such as the total weight of a structure, its ECI value and a cost indication. Now, all these MCA criteria can be given different weights, according to their level of importance per design strategy.
Finally, the MCA as explained above, can be tested on a case study from Witteveen+Bos. Based on the Program of Requirements as formulated by the client, both design strategy 2 and 3 could be followed during the design phase. The main difference between these two strategies can clearly be seen in the lay-out of the load bearing structure’s. After completing the MCA for both strategies, it can be concluded that a bolted steel structure is most likely the best option for design strategy 2. On the other hand, a bolted CLT structure seems to be the best solution when designing according to design strategy 3 for this specific case study. Concluding these results, it can be stated that the MCA can indeed help in selecting a design and building material, however in some cases, the differences between some building materials seem limited. Therefore, it can be said that the MCA is more likely to be helpful in eliminating some of the building materials from next design steps, based on their low MCA results.

Aluminium is a vital component of the world's economy, thanks to its versatile applications. However, the environmental impacts of primary production result in a growing desire and societal pressure to develop more efficient recycling techniques. Secondary aluminium is produced at 5% of the energy consumption used to produce primary aluminium. Unfortunately, many recycling techniques suffer from an undesired loss in quality and material due to the complex particle shapes, variety of alloys, and contaminants. This research focuses on a state-of-the-art scrap sorting technique that aims to overcome the problems associated with the singulation of particles with sizes up to 500mm (max. diameter). Singulation is the process where a random particle flow is regularized into an individually spaced 1D file of particles. Subsequent particle identification and sorting into multiple categories increases scrap quality to allow for more efficient up-cycling. A combination of literature study, model simulations and setup experiments is used to study the effects of particle- and equipment properties on obstructing processes. Firstly, this study focuses on three particle properties: Length-to-Width (LW) ratio, density, and complexity of shape. Four different samples are studied: Base case, high LW, high density, high complexity of shape. Obtained results show the adverse effects of increased LW-ratio on the singulation performance. An average LW-ratio increase from 2 to 6 decreases the singulation performance by 10-15%. Surprisingly, the expected frequent entanglement of complexly shaped particles was seldom observed. In addition, the flow of complexly shaped particles showed similar singulation rates compared to low LW particles. High density particles were only linked to minor obstructing events. Secondly, this study focuses on obstructing processes by studying the particle flow over and between setup equipment. Two processes are the most important: 1) transition behaviour (single particle flow) and 2) merging mechanisms (multiple particle flow). Video analysis has shown the adverse effects of unpredictable particle flow upon transitioning between setup stages. This results in an entirely random process, thereby deteriorating performance and rapidly wearing the chute surface. Unpredictable flow on the chute is primarily related to specific yet frequent circumstances. The amount of correction in flow a particle requires to align into a single file seems the best indicator. Centre-fed, parallel orientated particles require the least correction. Edge-fed, perpendicularly orientated particles require most. The latter is associated with the highest degree of unpredictable rolling. This observed phenomenon increases with particle size. The chute is designed to merge particles with crossing trajectories. Merging particles rotate around their point of contact as a whole until the combined bounding box is orientated parallel to the direction of flow. This explains the poor performance of high LW particles and surprisingly good performance of complex-shaped particles. The bounding box of merging high LW particles is already orientated parallel to the direction of flow. Limited rotational force is therefore exerted on the particles. In addition, the higher moment of inertia and chute design further restrict rotation towards sequential flow. Consequently, the current singulation process functions below its potential. The passive singulation process benefits from a reject of high LW particles towards the coarse faction (to be re-shredded) and smooth transition designs to reduce unpredictable flow.

The ambition of the Netherlands is to have a fully circular economy by 2050.
One of the steps to achieve this ambition is that in 2030 the tenders should have
circular ambitions at all governmental levels. However, at the moment, there are
insufficient tools for the municipality to make the practical implications of these
circular ambitions explicit. In a studied case-project in Reigersbos (Amsterdam),
where circular facades are being applied, a selection procedure has taken place
to unify different parties that are willing and able to enhance the circularity of
the project. Such a tender process is complex and time-consuming. A tool that
streamlines circular requirements can help the selection procedure for the parties involved early in the process and can actively keep track of realisation of
the set requirements during the process. Therefore, the thesis aims to develop a
circular tendering tool that actively helps the municipality and project developer
set circular ambitions and criteria for an arbitrary project location. The tool’s
concept is to categorize and assess the individual benefits of the circular measures in the chosen products, phases and parties, based on the principle of the circular economy. By utilizing this tool, it becomes possible to compare and select a facade system for the project. Furthermore, it also keeps track of the process by monitoring the set goals during the project for necessary adjustments and allows evaluating of the goals in the end.

Nowadays environmental issues like the depletion of the natural resources and the pollution of the environment have led many researchers to make new projects about the reuse of waste from construction and demolition again in concrete industry. Among available solutions are the partial replacement of cement with recycled ultrafine particles (RUP) and the reuse of recycled sand (RS) as substitute of natural sand in mortar/concrete mixtures. The aim of the present research is to investigate if the new mortar with recycled ultrafine particles can substitute the reference mortar made of virgin materials and to investigate the possible accompanying ecological and economic benefits. This will be demonstrated in terms of technical feasibility, ecology and economy of the new mortars. For the investigation of the main target of this MSc thesis, it was important three different experiments to be conducted. The 1st and 2nd experiment included the partial substitution of cement with RUP in 5%,10% and 15% respectively. The only difference was the size of RUP. In the 1st experiment were used only RUP below 125 microns and in the 2nd experiment only milled RUP below 45 microns. The 3rd experiment was more complicated with the simultaneous presence of RUP below 125 microns and the total replacement of natural sand with recycled sand. The w/b ratio was constant for the first two experiments at 0,5, but the w/c was increased as the replacement ratio of RUP also increased for all the experiments. The results were excellent about the fresh workability of the mortars in all the experiments with higher values of slump in contrast to the reference one from virgin materials. But there were some problems about the mechanical properties and especially the compressive strengths of the new mortars. The usage of smaller RUP below 45 microns improve the mechanical properties of the mortars with the highlight of the higher values for all the mortars in the test of flexural strength in the measurement after 14 days. Generally, it seems that as the replacement ratio of RUP was increased, the compressive strength of the mortars was decreased. For the 3rd experiment, the results regarding the mechanical properties were not very satisfactory despite the compensation with extra water. The quantity of this water has a crucial role for future researches and additionally lower replacement ratio than 100% is suggested for recycled sand.The next step was to reveal the possible ecological advantages from usage of this new mortar with recycled cement paste. For this investigation, an ecological analysis was conducted. This ecological analysis included in the first part a simulation in the lab experiments and in the second part a simulation in a conceptual recycling plant. The results are pleasant for the both cases regarding the GHG emissions and especially CO2. Initially, in the lab experiments, 5 % substitution with RUP instead of cement particles leads to 5,1% reduction of CO2 emissions, 10% substitution with RUP leads to 10,2% reduction of CO2 emissions and 15 % substitution with RUP leads to 14,8% reduction of CO2 emissions. Moreover, for the simulation of a conceptual recycling plant, the reuse of RUP in the mortar/concrete industry can lead to significant reduction of CO2 and less air pollution. Especially for the scenario in this MSc thesis, there is a potential environmental gain with total CO2 offset of 70,75 ton/day from this conceptual recycling plant. Up-to-day, the calcination of limestone to produce cement contributes to the emission of carbon dioxide. But the usage of recycled cement paste can reduce this bad consequence. The last step the investigation for the potential economic benefits from the reuse of the recycled materials and especially RUP in mortar/concrete industry. For this business case, an integration of Cost-Benefit Analysis with Cash-Flows was conducted for the previous conceptual recycling plant. According to this economic analysis, there are benefits from the creation of market for RUP, recycled sand and coarse aggregate like gravel and their demand as well as from the compensation by the European Union due to the reduction in CO2 emissions in this innovative conceptual recycling plant. The results revealed that the NPV was 5.955.631€ >0 for forecast of 18 year-operation. This can lead to a great payback period of the investment of about 33 months without the calculation of the taxation inside and with the conceptual discount rate at 10%. It has great perspectives for circular economy, with less waste, reuse of materials, less consumption of natural resources and less carbon emissions.In conclusion, although some technical drawbacks, the usage of RUP in new mortars instead of cement seems very satisfactory, and especially smaller RUP have beneficial effect to the mechanical properties of the mortar. Recycled sand is a material that needs more investigation about the appropriate parameters. The reuse of recycled materials and especially RUP contribute to some ecological advantages regarding the CO2 emissions. Also, there are possibilities for economic benefits for recycling plants with RUP as targeted material in products leading to the potential model of circular economy. Finally, RUP and other recycled materials can be the basis for sustainable and green development. Hence, recycled cement paste has as an impact the development of sustainable mortar in this industry.

Ammonia has been recognized as an effective leaching agent in hydro-metallurgical processes for the recovery of metals\cite{AmmLeach2013}. These processes result in ammonia-metal crystals, whereby in the last step, water and ammonia are removed from the crystals by a calcination process. In the past, the vaporized ammonia is considered a waste stream. However, regulations in the last few decades make it impossible for companies to dispose large amounts of ammonia into the air\cite{LRTAP2005}\cite{SOER2020}. Therefore, expensive installations, like catalytic oxidizers (CATOX) or membrane separators, need to be installed for ammonia reduction in the effluent gas stream. Climax Molybdenum b.v. installation in the Botlek Rotterdam produces pure molybdenum oxide according to the process described above. With the production, molybdenum oxide is leached in an ammonia solution to remove all contaminants, then crystallized and calcined. For the calcination process, the crystals are heated by a gas burner to vaporize the ammonia and water. The off-gas contains air, \ce{NH3}, \ce{CO2}, dust particles, and water vapor. The objective is to recycle the ammonia from the off-gasses of the calciner. Reclaiming the ammonia from the off-gas stream could reduce the costs up to \euro2000 per day. In this thesis, insights are gathered related to the chemical and physical reactions that occur when off-gasses of the calciner enter the process. Additionally, both the beneficial effects and potential complications of reclaiming ammonia from the off-gas are explained. This research is conducted by making mass balances on three different options for off-gas handling. These options include absorption into the leaching fluid (ARS:Ammonia Reduction System), absorption by water through a scrubbing system (AER:Ammonia Emission Reduction), and absorption by water through a scrubbing system with additional carbon dioxide removal with sodium hydroxide (AER+NaOH). In order to understand what happens when inorganic carbon (IC) comes into the system, experiments are conducted on both the leaching procedure of molybdenum and the stripping and condensing process of ammonia. Results show that inorganic carbon reaches its solubility in the leaching fluid at 2.12 mol/kg. Also, no effect on the solubility of ammonium molybdate was found, and no additional precipitation occurs on metals like zinc, calcium, magnesium, and iron. In the leaching fluid, the solubility of ammonium bicarbonate is reached at 183 grams per liter. Additionally, the influence of inorganic carbon on the stripping process showed that the strip rate of ammonia was reduced by 1.4. Also, could be concluded that stripping of ammonia was done efficiently at 80 degrees until the total ammonia nitrogen (TAN) mole concentration equals the total inorganic carbon (TIC) mole concentration. As a result, additional water treatment is needed for the discharge water to ensure the amount of ammonia does not exceed 25kg per day. Furthermore, another complication found was scaling. Scaling happens in both ARS and AER-system in the form of ammonium bicarbonate. In contrast, AER+NaOH system does not have the complication of scaling or ammonia in the discharge water, but the pH of the solution needs to be neutralized before discharge. Moreover, higher pH in the recycling water of the scrubber causes lower absorption efficiency of ammonia. ARS, AER, and AER+NaOH-system have an ammonia reduction of 41\%w, 33\%w, and 73\%w per day, respectively. For the ARS and AER-system, this means a cost-saving of \euro{1.160,-} and \euro{920,-} per day, respectively. The AER+NaOH-system has a direct cost of \euro{10.130,-} per day, due to the expensive sodium hydroxide. The cost of sodium hydroxide as a water treatment agent is higher than the cost savings of ammonia recovery from the off-gasses of the calciner. Therefore can be concluded that, ammonia recovery from off-gasses has large potential, but other methods are needed to treat ammonia in the discharge water to make it economically feasible. Further research can elaborate on alternatives for ammonia treatment in discharge water. Examples include the use of lime (CaO)\cite{AdPhysicochem2006}, increasing the stripping temperature\cite{Kim2013}, and leaching in sulfuric acid (\ce{H2SO4})\cite{EICforEngin2017}. However, this does not solve the scaling problem in the process. Therefore, further research should shine a light on the reduction of carbon dioxide that enters the chemical plant system. Examples proposed in this research, include condensing ammonia from the calciner off-gas stream. Multiple studies \cite{Xu1999}\cite{Mirl2020} show that, the condensing recovery is more effective for ammonia than carbon dioxide. Furthermore, this research also gives an economically feasible example of using an alternative calcination process without natural gas.

Phosphate is removed from wastewater to prevent eutrophication. Chemical phosphorus removal by iron dosing is commonly used for this purpose, where phosphorus is among others bound in the mineral vivianite (Fe(II)3[PO4]2 · 8 H2O). A molar Fe:P ratio of 2.5 in sludge will capture 70-90% of total phosphorus in vivianite after anaerobic digestion, a digestion method which offers ideal conditions for vivianite formation. Vivianite is paramagnetic, enabling it to be recovered by magnetic separation for recycling purposes. Phosphorus recycling from wastewater is of great importance, as in worst-case scenarios, 40-60% of all phosphate rock resources will be extracted by 2100. It is furthermore estimated that in Europe 20-30% of the fertilizer demand can be met by using phosphorus that ends up in sludge in European sewage treatment plants. To reduce processing costs of magnetic vivianite recovery, a pre-concentration step based on density concentration can be introduced, as vivianite particles are denser than organic material in sludge. This research investigated the feasibility of vivianite concentration from digested sewage sludge with a Multotec MX7 spiral concentrator. Spirals are applied in the mining industry for coal washing and pre-concentration of ores which are suspended in water. Particle separation on spirals is based on centrifugal and gravitational forces. Digested sewage sludge is more viscous than water, which affects the separation process on spiral concentrators. To investigate the influence of this high sludge viscosity on the spiral separation efficiency, laboratory experiments were performed. Diluting the sludge furthermore improved the concentration of solids towards
the product flow. However, spiral efficiencies were only 9%, while efficiencies over 80% were found for synthetic sludge, meaning that particle separation was limited. The iron concentration was highest in the product outlet and increased with dilution. The phosphorus content, however, was similar for all outlets and dilutions, suggesting that only Fe minerals other than vivianite, such as siderite and pyrite, concentrated towards the product flow. Additionally, a concentrated bed of sand grains was observed near the column after a dilution of 20%. While diluting the sludge improved the concentration of sand and heavy Fe minerals, it did not induce vivianite concentration.

Waste management in Lagos State is an unrelenting issue as the population increases exponentially per annum; there is a constant struggle with organization, transportation, and disposal of the daily waste generated per capita within the city. Of the waste generated in households in Lagos, plastic makes up a large percent of the non-organic waste found in dwellings. Waste from residences often end up pooling by the street side, and recycling is slow in gaining traction within the city. In addition, tropical cities like Lagos use HVAC systems to deal with high temperatures; this gives rise to high energy consumption in dwellings and offices alike. This is noteworthy because high energy consumption usually translates to energy expenses and in this city, with a population of 22 million, about 8.5% live in poverty with the middle-income earners toeing the line. Although a passive strategy like the use of thermal mass in buildings could improve energy efficiency, it is deemed more effective in regions with a significant difference in diurnal temperatures (>10°C). In Lagos state, however, there is no such significant range in temperatures. This served as the motivation for the inclusion of another strategy to support what is already existing – thermal insulation. This study explored the impact of thermal insulation made from plastic waste on energy savings and energy costs with the aid of DesignBuilder used to model dwellings with the climatic conditions of Lagos state. The focus of this study was on middle-class citizens in Lagos State and a survey was conducted using an online tool called Survicate, to assess their perception of the use of plastic waste on their facade. From the data, it was deduced that there is a possibility that people are willing to use plastic waste as thermal insulation when they are aware of the reduction of energy costs. For this study, five variations of thermal insulation were constructed, and experiments were carried out with the use of a hotbox to determine the thermal conductivity of these samples. The first sample was made from PET bottles with its cavity filled with textile waste; the second sample, a mould created from melted PET plastic that had been cut into tiny bits; the third variant was constructed from PET bottles with its cavity filled with water sachets (LDPE); the fourth sample, was built from crushed PET bottles and water sachets; and the last sample was made from empty PET bottles stacked on top of one another. The test sample with the least capability produced an expense reduction of N774.36/m2.year (€1.94/m2.year), while the best performing had a cost reduction of N1100.57/m2.year (€2.75/m2.year). Regardless of which insulation sample is applied, there would be savings in energy consumption, the cooling load demand of RAC (residential air-conditioning) systems would also decline, and there would be monetary savings as well. Resulting from the study’s outcome, it was recommended that a physical model be built in Lagos State to be studied further to see how well the materials perform under the actual climatic conditions in Lagos.

Large quantities of mine tailings are stored in mine tailings storage facilities. These facilities are only costing money for mining companies. In addition, these tailings storage facilities are prone to failure. To prevent this from happening these facilities have to be reinforced. This research introduces a concept to use geotextile tubes filled with mine tailings as reinforcing construction elements. That way value is assigned to the mine tailings while also making the storage facilities safer. However, pumping mine tailings in geotextile tubes is not an option due to the small particle sizes which will flow through the openings in the geotextile fabric. In addition, the contaminations in the mine tailings will also be mobilised using this method. Therefore, this research investigates potential enhancement of mine tailings to make them suitable to be pumped in geotextile tubes. The potential enhancement is in the form of flocculation and remediation. While flocculation increases the dewatering properties of mine tailings, the remediation will prevent the contaminations from mobilising. Test performed in this research include a series of jar tests, cone tests, two different strength tests and hanging bag tests. The results show that when flocculants are added to the tailings, the dewatering rate increases. The flocculant type which proved the most effective for these specific tailings type is a flocculant with an average molecular weight and average anionic value. Adding coagulant to the tailings further increases the dewatering rate of the tailings. When Ordinary Portland Cement is added, to stabilise and solidify the tailings, the dewatering rate increases even more. In addition, adding Ordinary Portland Cement to the tailings resulted in an increase of shear strength and unconfined compressive strength. After seven days of curing, the highest strength of curing was measured for the mixtures where fifteen mass percentage Ordinary Portland Cement was added. The mixture where the highest strength and the fastest dewatering rate was measured, was the mixture composes of mine tailings, flocculants, coagulants and fifteen mass percentage Ordinary Portland Cement.
With these results, it may be concluded that mine tailings can be used to fill geotextile tubes to form reinforcing construction elements if its dewatering behaviour is enhanced and its contaminants remediated.