The production of methanol by use of water electrolysis and hydrogenation of carbon dioxide (Power-to-Methanol) is a promising pathway to reduce greenhouse gas emissions. The concept of process intensification and the associated utilization of an in-situ coupling of methanol synthesis with proton-conducting Solid Oxide Electrolysis Cells (H+-SOEC) is a possible way to increase the energy efficiency of this process. Based on an extensive literature research, a novel Power-to-Methanol reactor concept for a concentric in-situ-integration of a tubular H+-SOEC has been designed, manufactured and operated at the Chair of Hydrogen and Nuclear Energy at the Technische Universität Dresden. The conducted experiments served as reference points for the process simulations performed in the second part of this thesis. Here, the Power-to-Methanol process has been modelled and simulated by means of process systems engineering methods to evaluate the in-situ-process in comparison to an conventional uncoupled set-up based on planar H+-SOECs. For this task, a novel and firm H+-SOEC process model was developed and implemented. In addition, the heat integration potential and profitability of the two Power-to-Methanol concepts have been investigated by Pinch Point and Techno-Economic Analysis. On the experimental side, a proof-of-concept of the novel reactor design was demonstrated, but limitations regarding the optimal thermal profile and operational flexibility of each process were identified. Furthermore, the methanol production rate showed potential for further improvement. The simulation results have helped to understand the process characteristics and to locate optimal operation points regarding current density, temperature and pressure. In an optimised operation scenario, high energy efficiencies for both tubular in-situ and planar set-ups have been achieved, by means of harnessing the heat integration potential through exothermic H+-SOEC operation. Notwithstanding the above, planar set-ups have demonstrated to be substantially more profitable than tubular systems. This has been the first investigation on Power-to-Methanol processes based on H+-SOEC. The present work helps to identify remaining development objectives for the use of H+-SOEC and Power-to-Methanol processes in general. The results from experiments and simulations indicate the challenging utilization of tubular electrolysis cells, but also revealed new research priorities that should be addressed in the future.

Due to the remote and dispersed nature of Alberta’s oil wells, it is not economical for the energy industry to capture all of the solution gas produced and as a result, the gas is being flared and vented in significant amounts. The objective of this research is to aid in the conversion of solution gas into dimethyl ether (DME) in a remote location by designing a distillation column that purifies DME and its reaction by-products, carbon dioxide, methanol and water. In order to develop an implementable solution, the distillation equipment must fit inside of a 40-foot shipping container to be transported to remote locations. Given the size constraint of the system, process intensification is the best strategy to efficiently separate the mixture. Several process intensification distillation techniques are explored, including semicontinuous distillation, the dividing wall column (DWC) and a novel semicontinuous dividing wall column (S-DWC). The traditional semicontinuous distillation column purifies DME to fuel grade purity, however the other components are not separated to a high enough grade given the height constrain of the system. The DWC and S-DWC both purify DME to its desired purity along with producing high purity waste streams. The S-DWC purifies the reaction intermediate methanol to a grade slightly higher than the DWC and is pure enough to recycle back to the reactor. An economic comparison is made between the three systems. While the DWC is a cheaper method of producing DME, the trade-off is the purity of the methanol produced. Overall, this research shows that it is possible to purify DME and its reaction by-products in a 40-foot distillation column at a cost that is competitive with Diesel. / Thesis / Master of Applied Science (MASc)

Process industries are cornerstones in today’s industrialized society. They contribute significantly in the manufacturing of various goods and products that are used in our day-to-day life. Our society’s paradigm of consumerism accompanied by a rise in global population drives an ever increasing demand for goods. One of many strategies developed to satisfy these demands and at the same time improve production capabilities is known as process intensification. As an example, this can be accomplished by implementation of devices using the principle of hydrodynamic and acoustic cavitation. High-intensity cavitation in the ultrasonic range can change the physical and chemical properties of a wide range of substances and hence, improve the production rate or quality. Despite the generally accepted benefits of hydrodynamic and acoustic cavitation, applications in the process industry are yet limited. The reasons are that the method requires extensive optimization, which depends on multiple process parameters and encounters problem in the implementation on a larger scale. Scalable cavitation reactor concepts for industrial applications need to meet challenges like stability and robustness, energy efficiency and high flow rates. This thesis focuses on the methodology for the design and optimization of a flow through cavitation reactor. An ultrasound reactor concept has been developed and tested for two different applications: i) Fibrillation processes typical for paper and pulp industry; ii) Metal leaching of mineral concentrates. Simulations were carried out using a commercially available software for multiphysics modeling which combines acoustics, structural dynamics, fluid dynamics and piezoelectrics. However, the optimization procedure requires extensive experimental work in parallel with multi-physical simulations. In general, the application leads to hydrodynamic initiation of small gas bubbles in the fluid to be excited and collapsed by high-intensity ultrasound. This transient collapse of the cavitation bubbles provides both mechanical and chemical effect on materials. The developed reactor has a power conversion efficiency of 36% in batch mode and is well suited for a scale-up. In flow-through mode, the cavitation effect improves extensively and provides stable results. Energy efficiency requires hydrodynamic initiation of cavitation bubbles, high acoustic cavitation intensity by multiple excitation frequencies adapted to the optimized reactor geometry, as well as optimal process pressure and temperature with respect to the materials to be treated. The impact of flow conditions and hydrodynamic cavitation is significant and almost doubles the yield at the same ultrasonic power input. In the case of fibrillation of cellulose fibers, results obtained indicate that generated cavitation intensity changes the mechanical properties of the fiber wall. In the case of leaching, experiments show that six hours of exposure gave a 57% recovery of tungsten from the scheelite concentrate at 80°C and atmospheric pressure. Future research will focus on different types of excitation signals, extended reactor volume, increased flow rates and use of a higher process temperature.

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[pt] Para atender a necessidade de se tornarem mais competitivas, as organizações passaram a adotar sistemas de trabalho de alta performance, com vistas a aumentar o envolvimento dos trabalhadores no processo produtivo. Neste modelo, a gestão e a organização do trabalho são centradas em trabalhadores altamente qualificados, engajados e com autonomia, e os resultados são atingidos através do desenvolvimento de uma força de trabalho mais motivada e comprometida. Todavia, esse sistema produz, também, um processo de intensificação do trabalho, que pode trazer impactos negativos sobre a força de trabalho. Apesar dessa possibilidade, nota-se que as empresas ditas de alta performance tendem a ser bastante atraentes para os profissionais, que muitas vezes disputam suas vagas em processos seletivos concorridos. Essa constatação motivou a realização do presente trabalho, que teve como objetivo analisar as bases do contrato psicológico acordado entre indivíduos e empresas reconhecidas pelo mercado por adotarem as práticas de trabalho de alta performance, pela perspectiva de profissionais da área de recursos humanos destas empresas. Os resultados permitiram identificar os acordos criados entre profissionais e organizações de alta performance, sugerindo que estas empresas oferecem oportunidades de crescimento na carreira e a possibilidade de um aprendizado intenso associado à autonomia e responsabilidade. Em troca, esperam que seus funcionários sejam flexíveis, multifuncionais, tenham uma dedicação incondicional aos resultados da empresa e sejam capazes de trabalhar num cenário de intensificação do trabalho, onde a qualidade de vida é algo que deve ser deixada em segundo plano. / [en] To meet the need of becoming more competitive, organizations have adopted systems of high-performance work, aimed at increasing employee involvement in the production process. In this model, management and work organization are focused on highly skilled, engaged and autonomous employees, and the results are achieved through the development of a more motivated and committed workforce. However, this system produces a process of intensification of work also, which may bring negative impacts on the workforce. Despite this possibility, we note that the so-called high-performance companies tend to be quite attractive to professionals, who often compete for jobs in their crowded selection processes. This finding motivated the present study, which aimed to analyze the foundations of the psychological contract agreed between individuals and companies recognized by the market by adopting the high-performance work practices, from the perspective of human resources professionals from these companies. The results have allowed identifying the established agreements between professionals and high performance organizations, suggesting that these companies offer opportunities for career growth and the possibility of an intense learning associated with autonomy and responsibility. In return, they expect their employees to be flexible, multifunctional, have an unconditional dedication to the company s results and be able to work against a intensifying work backdrop, where life balance is something that should be left in the background.

Facing the pressure of population growth and global warming, this dissertation provided an array of innovative carbon-efficient wastewater treatment technologies for resource recovery, process intensification, and anammox featured next generation biological nutrient removal (BNR) technologies. These technologies aim to supplant traditional carbon-intensive treatment processes with more sustainable alternatives. To this end, the dissertation first comprehensively reviewed what resources can be recovered from wastewater, and how these valuable resources can contribute to the carbon neutrality in water resource reclamation facilities (WRRFs) and help achieve sustainable society development. Then, the effect of mixed liquor recycle (MLR) configurations on the process intensification through continuous-flow aerobic granulation was explored in plug flow reactors. The results demonstrated that MLR configuration could hinder the sludge granulation, but the hindrance could be alleviated to some extent by its location change. In order to eliminate the energy consuming MLR, endogenous denitrification was taken advantage through a synergistic integration with partial nitrification, partial denitrification anammox (PdNA), and enhanced biological phosphorus removal (EBPR). This idea was tested in a pilot setup treating real primary effluent under highly variable influent conditions and low temperatures. The results showcased substantial carbon savings while meeting the stringent effluent requirements. To take a deeper dive into the PdNA performance and the underlying mechanisms, two parallel pilot-scale moving bed biofilm reactor (MBBR) treatment trains fed with methanol and glycerol, respectively, were operated in a local WRRF. Their efficacies in achieving stringent nutrient removal targets and carbon savings were compared. The impacts of operational conditions on the mechanisms and performance were elucidated. In the culmination of this dissertation, a sidestream process intensification and resource recovery technique, namely thermal hydrolysis pretreatment (THP) enhanced anaerobic digestion (AD), was experimented to compare the efficiencies between thermophilic and mesophilic AD when integrated with THP. To sum up, this dissertation not only advanced our understanding of carbon-efficient wastewater treatment processes but also laid the groundwork for their practical implementation, contributing to the global effort towards sustainability. / Doctor of Philosophy / Wastewater treatment consumes 3-4% of the energy produced in the U.S. and contributes to approximately 1.6% global greenhouse gas emissions. This dissertation aims to advance a series of carbon-efficient technologies specifically tailored for sustainable wastewater treatment. To this end, a variety of valuable resources that can be recovered or reused in wastewater treatment plants was firstly reviewed. Then, an advanced technology that can turn dispersed bacteria into bacteria aggregates was tested with real wastewater in a local wastewater treatment plant. Although these bacteria aggregates allow more wastewater to be treated with less small footprint, which was great, it was realized from this study that the formation of these bacteria aggregates was hindered by the nitrate water recycle which has been commonly practiced for using influent carbon for nitrogen removal. This nitrate water recycle consumed excessive energy for its high flow rate. To save this energy, a novel bioprocessing design was developed to eliminate the need for this nitrate water recycle by using carbon stored in bacterial cells. This new design also incorporated phosphorus recovery capacity and a low carbon nitrogen removal technique into one consolidated system to create an all-in-one solution to meet the stringent wastewater treatment requirement. This low carbon nitrogen removal technique harnessed a special group of bacteria that can use ammonia to reduce nitrite to nitrogen gas. Hence, only minor carbon source needs to be provided to reduce nitrate to nitrite for these bacteria to utilize. Two types of carbon sources, namely methanol and glycerol, were compared in a pilot-scale study to understand their efficiencies in generating nitrite. Results indicated that although both types of carbon sources can work, methanol is better suited for low strength wastewater treatment. These results provided an engineering basis for the full-scale application of the technology in the same wastewater treatment plant where the pilot study was performed. Besides liquid treatment, a carbon efficient solid treatment technology was also studied. The bottleneck constraining the rate of sewage sludge conversion to flammable menthane gas was identified, which provided engineering guidance for the design of the solid treatment process that can destroy more sewage sludge within smaller reactor spaces. In essence, this dissertation offers promising solutions for modern wastewater treatment plants to achieve low carbon wastewater treatment without compromising the treatment performance.

The Midwest US has experienced significant changes in agricultural land use and management practices in recent decades. Cropland expansion, crop rotation change, and crop phenology changes could lead to divergent environmental impacts on linked ecosystems. The overall objective is to examine agricultural land use and management changes and their impacts on water quality in the Midwest US, which is addressed in three separate studies. The first study examined spatial and temporal dimensions of agricultural land use dynamics in east-central Iowa, 2001-2012. Results of this study indicated that increases in corn production in response to US biofuel policies had been achieved mainly by altering crop rotation. This study also examined spatial relationships between cultivated fields and crop rotation practices with respect to underlying soils and terrain. The most intensively cultivated land had shallower slopes and fewer pedologic limitations than others, and the corn was planted on the most suitable soils. The second study characterized key crop phenological parameters (SOS and EOS) for corn and soybean and analyzed their spatial patterns to evaluate their change trends in the Midwest US, 2001-2015. Results showed that MODIS-derived SOS and EOS values are sensitive to input time-series data and threshold values chosen for crop phenology detection. The non-winter MODIS NDVI time-series input data, and a lower threshold value (i.e., 40%) both generated better results for SOS and EOS estimates. Spatial analyses of SOS and EOS values displayed clear south-north gradient for corn and trend analyses of SOS revealed only a small percentage of counties showed statistically significant earlier trends within a user-defined temporal window (2001-2012). The third study integrated remote sensing-derived products from the first two studies with the SWAT model to assess impacts of agricultural management changes on sediment and nutrient yields for three selected watersheds in the Midwest US. With satisfied calibration and validation results for stream flows, sediment and nutrient yields, considered under differing management scenarios, were compared at different spatial scales. Results showed that intensive crop rotation, advancing the planting date with the same length of growing season, and longer growing seasons, dramatically increased, maintained, and slightly reduced sediment, total nitrogen, and total phosphorous yields, respectively. Overall, these studies together illuminate relationships between broad-scale agricultural policies, management decisions, and environmental impacts, and the value of multi-temporal, broad-scale, geospatial analysis of agricultural landscapes. / Ph. D.

No / The article focuses on emotional labour and self-identity at the Irish-owned Aer Lingus airline from 1998 to 2008. It has been suggested that emotional labour is likely to be an increasingly important feature of frontline service jobs. However, in this case management has reduced the level of emotional labour requirement while work organization, recruitment policy and training have changed to focus on sales and lower labour costs, intensifying workloads and reducing cabin crew autonomy. Although some may suggest that a reduction in emotional labour requirement would be a positive outcome for employees, this is not how it has been perceived by some cabin crew. Long-serving cabin crew in particular see these changes as an attack on their professionalism and a challenge to their identity as skilled emotion workers.

The Midwestern United States is a nationally and globally important producer of agricultural products and uses intensive practices to achieve high grain yields. However, intensive agriculture is a major contributor of nitrogen and phosphorus export to the Mississippi River and the hypoxic zone in the Gulf of Mexico. Cover cropping is a recommended conservation practice for providing soil cover throughout the winter and taking up nutrients that may otherwise be lost in bare fallow systems, but the associated costs limit widespread adoption of this practice. Double cropping, which involves growing two crops in one year, is functionally similar to cover cropping and can be harvested for an additional income, but the water quality impacts of applying fertilizer to maximize yields and the systemic impacts of intensification with another crop on corn-soybean rotations are not well understood. This two-year, plot scale study in Carbondale, Illinois was designed to assess nutrient leaching, referring to nitrate-N, ammonium-N, and dissolved reactive phosphorus (DRP), nutrient availability, and crop yields when using bare fallow, cereal rye (Secale cereale) cover crops, or winter wheat (Triticum aestivum) double crops with varying nitrogen fertilizer rates and timings in the winter seasons of corn-soybean rotations. Four blocks with randomly assigned treatments comprised of two treatment factors were used. These treatment factors included rotations with either bare fallow or cover crops in alternate winters and winter wheat fertilizer management intensity with a high fertilizer treatment level, grower recommended rates applied at planting, tillering, and jointing, a medium fertilizer treatment level, grower recommended rates applied at tillering and jointing, a low fertilizer treatment level, with reduced nitrogen rates applied at tillering and jointing, and a no fertilizer treatment level, which was used as either corn-soybean or corn-cover crop-soybean-cover crop control. Additional nutrient inputs from fertilizers in the winter wheat seasons did not significantly increase nitrate-N, ammonium-N, or DRP leaching in the 2021-2022 winter wheat sampling season and nitrate-N and ammonium-N leaching was significantly less in some or all the winter wheat plots compared to the control plots. Winter wheat yields and nitrogen uptake in 2022 were significantly greater in medium fertilizer plots while yield-based nitrogen leaching and partial nitrogen balances were significantly greater in high fertilizer treatments, indicating that delayed fertilization in winter wheat can improve nitrogen use efficiency and yields. Soybean yields were significantly greater in plots without winter wheat due to a longer growing season, but plant available ammonium-N concentrations, which were greater in winter wheat plots, also had a significant negative relationship with soybean yields, indicating that this may have impeded biological nitrogen fixation. Using cover crops in alternate winters reduced nitrate-N leaching by 106% and plant available nitrate-N concentrations by 107% in the season as well as the subsequent corn season by 66% and 90%, respectively, compared to the bare fallow plots, and the decreased plant available nitrate-N concentrations in cover crop plots caused a 6% yield penalty in the corn harvest. Despite yield penalties to cash crops from winter crops, the use of double crops was the only factor that significantly impacted total crop yields. The use of cover crops in alternate winters was the most significant factor in nutrient leaching, demonstrating that these practices can be used to increase total crop yields without contributing significantly to nutrient export. For farmers concerned with the costs of cover cropping, double cropping is a practice that can provide some of the same ecosystem services while also providing an additional financial incentive.