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- Beckinghausen, Aubrey, 1991-
(författare)
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Investigation of nitrogen recovery from concentrated wastewater
- 2021
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Nitrogen recovery from wastewater treatment for fertilizers is a research topic that exists at the intersection of multiple topics important to the future of sustainable society. First, nitrogen recovery from wastewater implies a departure from the current methods of nitrogen mitigation, which involve nitrogen removal by conversion of various aqueous species to inert nitrogen gas. Secondly, by recovering nitrogen from wastewater specifically, there is the opportunity to begin a circular economy where value added products can be obtained from material that has historically been seen as a “waste”. Current wastewater treatment involves nitrogen removal through the biological transformation of aqueous nitrogen species to inert nitrogen gas. This process is energy intensive and risks the production of air pollutants such as N2O as intermediates in the biological transformation. If this nitrogen can be captured in a form that can be reused, a valuable product can be achieved with the potential reduction of both the energy required at the wastewater treatment plant as well as the carbon footprint. Finally, by recovering nitrogen in a form that can be used in agriculture as a fertilizer, additional environmental benefits can be realized by reducing reliance on Haber-Bosch based ammonia production, which is also energy intensive and contributes harmful emissions to the atmosphere.The work described in the following licentiate aims to consider the current status of nitrogen recovery from wastewater for fertilizers as a research topic. Literature was analytically examined to compare different techniques in terms of energy requirements, cost for fertilizer production, market for final fertilizer product, and technological readiness. The most interesting findings from this review were that there seems to be a disconnect between the fertilizer product produced by nitrogen recovery techniques and the market, which will become a challenge if these techniques are implemented at a large scale. The attitude of the farmers with regards to fertilizers from waste was overall positive, with their concerns mainly focused on the performance ability and cost of the product. Additionally, many techniques such as microbial fuel cells and microbial electrolysis cells have been unable to move past the laboratory phase despite being researched for many years. This indicates there are cost and technological barriers that are preventing the further scale up and implementation of these techniques. Energy and cost analyses will be crucial to motivate investment into these processes, and these are missing for many of the techniques found around this topic.To contribute to this field, experimental work was also included to assess the potential for ammonium adsorption from concentrated wastewater for fertilizer production. The experimental work focused on the utilization of the solid product of pyrolysis of sewage sludge (biochar) for adsorption and explored the potential enhancement of the char with various chemical treatments. The char with the best ammonium adsorption performance was found to be using a treatment of HNO3 followed by and NaOH, with an adsorption capacity of 4 mg NH4/g biochar. This char was compared with commercially activated carbon and clinoptilolite for full scale applications. It was found that even with this increased adsorption capacity, the use of chemically enhanced sewage sludge biochar for full scale applications is not realistic. The amount of raw material required for the complete recovery of ammonium from reject water at the municipal wastewater treatment plants exceeds the total amount of sewage sludge generated. Therefore it is recommended that the goal of incorporating sewage sludge biochar with wastewater treatment is to produce a solid fertilizer product loaded with ammonium (which would provide ammonium-N and phosphorus for plant growth, as well as carbon and other minerals for soil amendment) rather than having the goal be complete ammonium recovery from the wastewater stream.
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- Bel Fdhila, Rebei, et al.
(författare)
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PREDICTION AND MEASUREMENTS OF THE GAS BUBBLES INDUCED MIXING IN A BIO-REACTOR WATER MODEL
- 2013
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Biogas is a fuel gaining increased interest. To be commercially viable the biogas production process needs to be further improved with advanced industrial standards where the technical, economic and environmental aspects are fully considered.Understanding fluid dynamics and the microbial reactions in the digestion process is necessary to accurately model and predict the biogas production. In connection with the Swedish company SvenskVäxkraft AB we focus on reactors where part of the produced gas is re-injected at the bottom to generate a strong recirculation with a gas-lift effect with a rising flow in the core. The mixture motion in this type of bio-reactors is entirely induced by the gas.Computational fluid dynamics (CFD) is used to study the effect of gas plumes of bubbles in the range smaller than 10mm with a maximum local gas volume fraction lower than 10%. This study shows that considering the appropriate models to account for the added agitation and turbulence by the bubbles improves the prediction of the liquid flow characteristics. Neglecting the induced bubble effect leads to erroneous results where the radial dispersion of the gas concentration, the liquid velocity and the turbulence are significantly underestimated.To validate the model we performed local measurements in an experimental facility where a laboratory water-model is equipped with advanced instruments to measure the gas volume fraction as well as the liquid and gas vertical velocities.It was found that using the bubble induced turbulence model by Sato et al. [8] with the Tomyami models for the drag and lift forces [3-6], provides predictions in good agreement with the measured quantities.This study shows that for such processes where the flow is mainly created by the bubbles presence, the pseudo-turbulence (the turbulence induced by the bubbles) and the bubble size distribution need to be properly considered.
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- Blackman, Corey
(författare)
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Evaluation of Modular Thermally Driven Heat Pump Systems
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The building sector accounts for approximately 40% of primary energy use within the European Union, therefore reductions in the energy use intensity of this sector are critical in decreasing total energy usage. Given that the majority of energy used within the built environment is for space conditioning and domestic hot water preparation, prudence would suggest that decreasing primary energy used for these end purposes would have the biggest overall environmental impact. A significant portion of the energy demands in buildings throughout the year could potentially be met using solar energy technology for both heating and cooling. Additionally, improving the efficiency of current heating and cooling appliances can reduce environmental impacts during the transition from non-renewable to renewable sources of energy. However, in spite of favourable energy saving prospects, major energy efficiency improvements as well as solar heating and cooling technology are still somewhat underutilised. This is typically due to higher initial costs, and lack of knowledge of system implementation and expected performance. The central premise of this thesis is that modular thermally (i.e., sorption) driven heat pumps can be integrated into heating and cooling systems to provide energy cost savings. These sorption modules, by virtue of their design, could be integrated directly into a solar thermal collector. With the resulting sorption integrated collectors, cost-effective pre-engineered solar heating and cooling system kits can be developed. Sorption modules could also be employed to improve the efficiency of natural gas driven boilers. These modules would effectively transform standard condensing boilers into high efficiency gas-driven heat pumps that, similar to electric heat pumps, make use of air or ground-source heat. Based on the studies carried, sorption modules are promising for integration into heating and cooling systems for the built environment generating appreciable energy and cost-savings. Simulations yielded an annual solar fraction of 42% and potential cost savings of €386 per annum for a sorption integrated solar heating and cooling installation versus a state-of-the-art heating and cooling system. Additionally, a sorption integrated gas-fired condensing boiler yielded annual energy savings of up to 14.4% and corresponding annual energy cost savings of up to €196 compared to a standard condensing boiler. A further evaluation method for sorption modules, saw the use of an artificial neural network (ANN) to characterise and predict the performance of the sorption module under various operating conditions. This generic, application agnostic model, could characterise sorption module performance within a ± 8% margin of error. This study thus culminates in the proposal of an overall systematic evaluation method for sorption modules that could be employed for various applications based on the analytical, experimental and simulation methods developed.
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- Daraei, Mahsa, 1991-, et al.
(författare)
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Impacts of integrating pyrolysis with existing CHP plants and onsite renewable-based hydrogen supply on the system flexibility
- 2021
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Ingår i: Energy Conversion and Management. - : Elsevier BV. - 0196-8904 .- 1879-2227. ; 43
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The share of renewable energy sources in the primary energy use is increasing worldwide. Given the intermittency of the energy supply from renewables, it is important to increase flexibility in the system to respond to the imbalances between energy demand and supply. Several flexibility options such as power storage and energy integration are currently in use, mostly at small scales. The increased energy supply from renewables and the flexibility solutions can influence the production planning of existing thermal energy conversion plants. In this study, integration of energy technologies including a hydrotreated pyrolysis oil production integrated with existing CHP plants is investigated as a flexibility solution. The system interacts with potential power generation from rooftop PV systems integrated with power-to-hydrogen storage. A cost-optimization model is developed using MILP method. The study focuses on the system flexibility and operational strategy of the existing CHP plants considering market trends, climate changes, and future energy developments with increased penetration of heat pumps and electric vehicles but less fossil fuels use. The results indicate that the suggested integrated system can increase the local energy supply by 33 GWh. Moreover, the power-to-hydrogen storage and onsite hydrogen use can increase the share of renewables in energy supply by 6%. Optimization of the developed scenarios for future energy-related changes indicates that the market trends could significantly reduce the performance of the system by 21% but increase the penetration of renewables in the system by 8%. Overall, scenario analysis shows the potential of using such a polygeneration system for flexible energy supply including existing CHP plants.
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- den Boer, Emilia, et al.
(författare)
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Current Status of Waste-to-Energy Utilisation in some parts of Baltic Sea Region
- 2011
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Ingår i: Journal of Finnish Universities of Applied Sciences. - : Journal of Finnish Universities of Applied Sciences. - 1799-6848. ; 2
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- This paper presents the results of preliminary assessment of the current status ofwaste-to-energy utilisation in selected regions, which was conducted within theREMOWE (Regional Mobilizing of Sustainable Waste-to-Energy Production)project. The REMOWE project is part of the Baltic Sea Region Programme 2007-2013 and has been partly-financed by the European Union. The most and least advanced regions with regard to the renewable energy share in final energyconsumption were presented, also some Finnish data was included. The wastetypes which were identified as relevant for energy recovery include municipalwaste, sewage sludge, industrial waste, as well as agricultural waste and byproducts. In both considered regions there is high energy recovery potential.
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| 9. |
- den Boer, Jan, et al.
(författare)
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ENERGY POTENTIAL FROM RESIDUES IN NORTHERN CENTRAL EUROPEAN REGIONS
- 2012
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In this paper the results of a study on the energy potential of residual materials in 5 regions in the Northern Central European area are presented. The highest potential for waste-to-energy is provided by the incineration of municipal residual waste and the digestion of manure. Related to the number of inhabitants, the potential is the highest in North Savo, whereas the current utilisation is by far the highest in the County of Västmanland. The total potential of waste-to-energy for the considered regions is the highest for Western Lithuania at app. 7%, with the other regions varying between 2,5 and 4% of the total primary energy use. The following waste-to-energy installations should be planned: waste incinerators (Estonia, Western Lithuania and Lower Silesia); energy recovery from waste derived fuels (North Savo, Lower Silesia and the County of Västmanland); anaerobic digestion of biodegradable part of municipal waste and of agricultural waste and by-products (Lower Silesia) as well as sewage sludge drying in Western Lithuania and Lower Silesia.
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| 10. |
- Dong, Beibei
(författare)
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Dynamic modeling of MEA-based CO2 capture in biomass-fired CHP plants
- 2024
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Global warming is a significant threat to our planet. Adopting the Paris Agreement is a global action that aims to reduce greenhouse gas emissions. An extensive deployment of negative emission technologies (NETs) is required to achieve the targets set by the Paris Agreement. Bioenergy with carbon capture and storage (BECCS) is emerging as one of the most promising NETs. Among different biomass utilization processes, integrating BECCS with biomass-fired and waste-fired combined heat and power (bio-CHP and w-CHP) plants has been considered the most feasible solution. Bio/w-CHP plants are characterized by high fluctuations in operation, which can result in more dynamic variations of flue gas (FG) flowrates and compositions and available heat for CO2 capture. Such changes can clearly affect the performance of CO2 capture; therefore, doing dynamic simulations becomes crucial.This thesis aims to investigate the performance of different dynamic physical model-based approaches and provide suggestions for approach selection. In addition, the data-driven modeling approach, which is an emerging technology, has also been tested.Three physical model-based approaches include the ideal static model (IST), the dynamic approach without control (Dw/oC), and the dynamic approach with control (DwC). To compare their performance, the operating data from an actual waste CHP plant is employed. Various cases have been defined considering different critical operating parameters, including the FG flowrate, the CO2 concentration (CO2vol%), and the available heat for CO2 capture. Apparent differences can be observed in the results from different approaches. For example, when the CO2vol% drops from 15.7 % to 9.7 % (about 38 %) within 4 hours, the difference in the captured CO2 can be up to 22% between DwC and Dw/oC. It is worth noting that when there are both increases and decreases in the variations of parameters, the differences become smaller. Based on the comparison, the recommendations on approaches have been summarized. Dw/oC is recommended for checking the boundary of safety operation by the response analysis. DwC is recommended for designing the control system, observing the flexible dynamic operation, estimating the short-term CO2 capture potential, and optimizing the hourly dynamic operation. IST is recommended for estimating the long-term CO2 capture potential, and optimizing the long-term dynamic operation when the input parameters vary not as often as hourly.A data-driven model, Informer, is developed to model CO2 capture dynamically. The dataset is generated by using a physical model. The FG flowrate, the CO2vol%, the lean solvent flowrate, and the available heat for CO2 capture are employed as input parameters, and the CO2 capture rate and the energy penalty are chosen as outputs. The results show that Informer can accurately predict dynamic CO2 capture. The mean absolute percentage error (MAPE) was found to be 6.2% and 2.7% for predicting the CO2 capture rate and energy penalty, respectively.
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