There is an urgent need for wastewater treatment plants (WWTPs) to adapt to a rise in water and energy demands, prolonged periods of drought, climate variability, and resource scarcity. As population increases, minimizing the carbon and energy footprints of wastewater treatment, while properly managing nutrients is crucial to improving the sustainability WWTPs. Integrated resource recovery can mitigate the environmental impact of wastewater treatment systems; however, the mitigation potential depends on various factors such as treatment technology, resource recovery strategy, and system size. Amidst these challenges, this research seeks to investigate the environmental sustainability of wastewater treatment plants (WWTPs) integrating resource recovery (e.g., water reuse, energy recovery and nutrient recycling) in different contexts (developing versus developed world) and at different scales (household, community, and city). The over-arching hypothesis guiding this research is that: Context and scale impact the environmental sustainability of WWTPs integrated with resource recovery. Three major research tasks were designed to contribute to a greater understanding of the environmental sustainability of resource recovery integrated with wastewater treatment systems. They include a framework development task (Chapter 2), scale assessment task (Chapter 3), and context assessment task (Chapter 4). The framework development task includes a critical review of literature and models used to design a framework to assess the environmental sustainability of wastewater treatment and integrated resource recovery strategies. Most studies used life cycle assessment (LCA) to assess these systems. LCA is a quantitative tool, which estimates the environmental impact of a system over its lifetime. Based on this review, a comprehensive system boundary was selected to assess the life cycle impacts of collection, treatment, and distribution over the construction and operation and maintenance life stages. Additionally, resource recovery offsets associated with water reuse, energy recovery, and nutrient recycling are considered. The framework’s life cycle inventory includes material production and delivery, equipment operation, energy production, sludge disposal, direct greenhouse gas (GHG) emissions, and nutrients discharged to the environment. Process-based LCA is used to evaluate major environmental impact categories, including global impacts (e.g., carbon footprint, embodied energy) and local impacts (e.g., eutrophication potential). This is followed by an interpretation of results using sensitivity or uncertainty analysis. The scale assessment task investigates how scale impacts the environmental sustainability of three wastewater treatment systems integrated with resource recovery in a U.S. context. Household, community, and city scale systems using mechanized technologies applicable to a developed world setting were investigated. The household system was found to have the highest environmental impacts due high electricity usage for treatment and distribution, methane emissions from the septic tank, and high nutrient discharges. Consequently, the life cycle impacts of passive nutrient reduction systems with low energy usage at the household level merit further investigation. The community scale system highlights trade-offs between global impacts (e.g., embodied energy and carbon footprint) and local impacts (e.g., eutrophication potential) where low nutrient pollution can be achieved at the cost of a high embodied energy and carbon footprint. The city scale system had the lowest global impacts due to economies of scale and the benefits of integrating all three forms of resource recovery: Energy recovery, water reuse, and nutrient recycling. Integrating these three strategies at the city scale led to a 49% energy offset, which mitigates the carbon footprint associated with water reuse. The context assessment task investigates how context impacts the environmental sustainability of selected community scale systems in both Bolivia and the United States. In this task, rural developing world and urban developed world wastewater management solutions with resource recovery strategies are compared. Less mechanized treatment technologies used in rural Bolivia were found to have a lower carbon footprint and embodied energy than highly mechanized technologies used in urban United States. However, the U.S. community system had a lower eutrophication potential than the Bolivia systems, highlighting trade-offs between global and local impacts. Furthermore, collection and direct methane emissions had more important energy and carbon implications in Bolivia, whereas treatment electricity was dominant for the U.S. community system. Water reuse offsets of embodied energy and carbon footprint were higher for the U.S community system, because high quality potable water is replaced instead of river water. In contrast, water reuse offsets of eutrophication potential were high for the Bolivia systems, highlighting the importance of matching treatment level to end-use application. One of the Bolivia systems benefits from the integration of water, energy, and nutrient recovery leading to beneficial offsets of both global and local impacts. This research can potentially lead to transformative thinking on the appropriate scale of WWTPs with integrated resource recovery, while highlighting that context lead to changes in the dominant contributors to environmental impact, appropriate technologies, and mitigation strategies.

A CO2 emission analysis and system investigation of a direct fuel cell waste energy recovery and power generation system (DFC-ERG) for pressure letdown stations was undertaken. The hybrid system developed by FuelCell Energy Inc. is an integrated turboexpander and a direct internal reforming molten carbonate fuel cell system in a combined circle. At pressure letdown stations, popularly called city gates, the pressure of natural gas transported on long pipelines is reduced by traditional pressure regulating systems. Energy is lost as a result of pressure reduction. Pressure reduction also results in severe cooling of the gas due to the Joule Thompson effect, thus, requiring preheating of the natural gas using traditional gas fired-burners. The thermal energy generated results in the emission of green house gases. The DFC-ERG system is a novel waste energy recovery and green house gas mitigation system that can replace traditional pressure regulating systems on city gates. A DFC-ERG system has been simulated using UniSim Design process simulation software. A case study using data from Utilities Kingston’s city gate at Glenburnie was analysed. The waste energy recovery system was modelled using the design specifications of the FuelCell Energy Inc’s DFC 300 system and turboexpander design characteristics of Cryostar TG120. The Fuel Cell system sizing was based on the required thermal output, electrical power output, available configuration and cost. The predicted performance of the fuel cell system was simulated at a current density of 140mA/cm2, steam to carbon ratio of 3, fuel utilization of 75% and oxygen utilization of 30%. The power output of the turboexpander was found to strongly depend on the high pressure natural gas flowrate, temperature and pressure. The simulated DFC-ERG system was found to reduce CO2 emissions when the electrical power generated by the DFC-ERG system replaced electrical power generated by a coal fired plant. / Thesis (Master, Chemical Engineering) -- Queen's University, 2010-08-31 02:02:11.392

Les composés traces présents dans les biogaz sont un frein à leur valorisation énergétique. Trois familles ont été identifiées comme particulièrement nocives pour les catalyseurs des reformeurs externes et pour l’anode des piles à combustible de type SOFC : les composés soufrés, siliciés et chlorés. Un traitement poussé du biogaz est donc indispensable pour une telle application. Ce travail à caractère expérimental s’intéresse au développement d’un système de traitement d’affinage destiné à l’adsorption de ces composés. Des matériaux adsorbants ont été sélectionnés pour leur efficacité dans l’élimination du sulfure d’hydrogène (H2S – composé soufré), de l’octaméthylcyclotétrasiloxane (D4 – composé silicié) et du cis-1,2-dichloroéthène (C2H2Cl2 – composé chloré), molécules cibles représentatives des trois familles préjudiciables. La zéolithe étudiée présente la meilleure efficacité d’élimination de l’H2S, tandis que le gel de silice est plus adapté à l’adsorption du D4. Une étude paramétrique a mis en évidence l’influence de la hauteur de lit d’adsorbant, de la concentration en polluant, du débit de gaz, de la présence de composés traces en mélange et de l’humidité sur les performances épuratoires. Des essais sur un biogaz brut d’installation de stockage de déchets non dangereux ont montré qu’il est possible de maintenir une concentration en H2S sous le seuil de tolérance de 1 ppmvH2S du reformeur. En s’appuyant sur des caractérisations physico-chimiques des adsorbants, des hypothèses concernant les mécanismes de rétention ont été proposées pour les couples zéolithe + H2S et gel de silice + D4. L’H2S est adsorbé puis oxydé en soufre élémentaire à la surface de la zéolithe. Lors de l’adsorption sur gel de silice, le D4 semble polymériser en surface. Ces deux phénomènes empêchent la régénération des adsorbants. Une première approche de modélisation des phénomènes d’adsorption pour le couple gel de silice + D4 a permis de déterminer le coefficient global de transfert de masse. Les courbes de percée obtenues expérimentalement pour différentes masses d’adsorbant ont été simulées avec succès. Des « règles de dimensionnement » ont été proposées pour un dimensionnement industriel d’un traitement d’affinage pour une valorisation en SOFC. L’analyse technico-économique a montré que la filière SOFC envisagée est viable techniquement, mais pas économiquement, la technologie SOFC étant encore trop coûteuse par rapport aux techniques de valorisation conventionnelles. Toutefois, la solution semble prometteuse d’un point de vue environnemental. / Biogas energy use is hampered by the presence of trace compounds. Three contaminant families are particularly detrimental for external reforming catalysts and solid oxide fuel cell (SOFC) anodes: sulfur-containing compounds, volatile organic silicon compounds (VOSiC) and chlorinated compounds. Therefore, a thorough biogas treatment is necessary for such an application. This experimental work deals with the development of a polishing treatment for the adsorption of these contaminants. Adsorbents were selected for their efficiency to remove hydrogen sulfide (H2S – sulfur-containing compound), octamethylcyclotetrasiloxane (D4 – VOSiC) and cis-1,2-dichloroéthene (C2H2Cl2 – chlorinated compound), molecules representative of the three harmful families. The studied zeolite showed the best efficiency for H2S removal whereas silica gel performed best for D4 adsorption. A parametric study highlighted the influence of adsorbent bed height, contaminant concentration, gas flow rate, the presence of contaminants in mixture and humidity on purification performance. Adsorption tests with a raw landfill biogas showed that it is possible to guarantee an H2S concentration below the 1 ppmvH2S tolerance limit of the reformer. Using adsorbent physicochemical characterizations, hypothesis about retention mechanisms were proposed for the couples zeolite + H2S and silica gel + D4. H2S is adsorbed and then oxidized into elemental sulfur at the surface of the zeolite. During the adsorption on silica gel, D4 seems to polymerize on the surface. These two phenomena prevent the regeneration of the adsorbents. A first modeling approach of the adsorption phenomena involved for the couple silica gel + D4 allowed the determination of the global mass transfer coefficient. Experimental breakthrough curves obtained for different masses of adsorbent were successfully simulated. Some “dimensioning rules” were proposed for the industrial design of a polishing treatment able to produce a biogas with the quality required to feed an SOFC. The techno-economic analysis showed that the SOFC solution is technically feasible but not economically viable because SOFC technology is still too costly compared to conventional conversion devices. However, the solution seems promising from an environmental point of view.

Burning trash should not be considered “renewable energy.” However, the federal government and as many as twenty-three states classify waste-to-energy recovery (WTE), or the incineration of garbage, as a renewable energy source that is eligible for a host of financial incentives. This paper discusses how WTE qualifies as an energy source that can be included in a state’s Renewable Portfolio Standard (RPS), or regulations that require energy producers to source a specific percentage of energy production from renewable energy sources, claiming the same benefits as cleaner, more sustainable energy sources such as solar, wind, and geothermal power. Upon evaluating incentives and programs for which WTE is eligible, I will argue that WTE is neither an environmentally nor economically viable energy solution. By analyzing WTE policy in the state of Maryland, I examine how RPSs contribute to the longevity of this unsustainable practice, calling for an elimination of WTE from RPS policy and federal incentive programs.

This diploma thesis deals with optimization models with design of a new waste management infrastructure in the Czech Republic, such that combustible waste, which is not utilized by the material recovering, can be used by energy recovering. This task is handled by optimization models, including trac and mixing problems. First of all, the concepts of graph theory and optimization are presented in this paper. Subsequently, some of the GAMS functions are discussed, and later the VBA programming language used to handle the larger data quickly is presented. In the main part, three gradually expanding models are developed. At the end the data from the waste management information system are implemented into them.

In this work is processed a survey of perspective alternative drives in motor vehicles. There are main characteristic for each mentioned drive, their advantages and disadvantages and problems associated with their use in vehicles. The work is aimed at gas engines, electro mobiles, hybrid drives and hydrogen, therefore the most likely drives the future.

The diploma thesis is focused on the evaluation of small-scale waste to energy plants in the Czech Republic. In the first part, there is a survey of the corresponding literature and general evaluation of the specificities of these plants. The next section analyzes the technical and economic indicators of a specific technology by Microsoft Excel model. Finally, recommendations for small-scale waste to energy plants arising from the model are summarized.

This research work is focused on a conceptual combination of membrane-based energy recovery ventilator (ERV) and phase change material (PCM) to provide energy savings in building heating, ventilation & air-conditioning (HVAC) systems. An ERV can recover thermal energy and moisture between the outside fresh air (OFA) entering into the building and the exhaust air (EA) leaving from the building thus reducing the energy consumption of the HVAC system for cooling and heating the spaces inside the building. The membranes were stacked parallel to each other forming adjacent channels in a counter-flow arrangement for OFA and EA streams. Heat and moisture is diffused through the membrane core. Flat-plate encapsulated PCM is arranged in OFA duct upstream/downstream of the ERV thereby allowing for further reduction in temperature by virtue of free cooling. Paraffin-based PCMs with a melting point of 24°C and 31°C is used in two different configurations where the PCM is added either before or after the ERV. Computational fluid dynamics (CFD), and heat and mass transfer modeling is employed using COMSOL Multiphysics v5.3 to perform the heat and mass transfer analysis for the membrane-based ERV and flat-plate PCMs. An 8-story office building was considered to perform building energy simulation using eQUEST v3.65 from Department of Energy (DOE). Based on the heat and mass transfer analysis, it is found that the sensible effectiveness (heat recovery) stood in the range of 65%-97% while the latent effectiveness (moisture recovery) stood at 55%-80%. Also, the highest annual energy savings achieved were 72,700 kWh in electricity consumption and 358.45 MBtu in gas consumption.

Energy recovery ventilation (ERV) systems are designed to decrease the energy consumed by building HVAC systems. ERV’s scavenge sensible and latent energy from the exhaust air leaving a building or space and recycle this energy content to pre-condition the entering outdoor air. A few studies found in the open literature are dedicated to developing detailed numerical models to predict or simulate the performance of energy recovery wheels and desiccant wheels. However, the models are often computationally intensive, requiring a lot of time to perform parametric studies. For example, if the physical characteristics of a study target change (e.g., wheel diameter or depth) or if the system runs at different operating conditions (e.g., wheel rotation speed or airflow rate), the model parameters need to be recalculated. Hence, developing a mapping method with better computational efficiency, which will enable the opportunity to conduct extensive parametric or optimal design studies for different wheels is the goal of this research. In this work, finite difference method (FDM) numerical models of energy recovery wheels and desiccant wheels are established and validated with laboratory test results. The FDM models are then used to provide data for the development of performance mapping methods for an energy wheel or a desiccant wheel. After validating these new mapping approaches, they are employed using independent data sets from different laboratories and other sources available in the literature to identify their universality. One significant characteristic of the proposed mapping methods that makes the contribution unique is that once the models are trained, they can be used to predict performance for other wheels with different physical geometries or different operating conditions if the desiccant material is identical. The methods provide a computationally efficient performance prediction tool; therefore, they are ideal to integrate with transient building energy simulation software to conduct performance evaluations or optimizations of energy recovery/ desiccant wheel integrated HVAC systems.

Container traffic in seaports around the world in constantly increasing, with energy costs being a significant part of the total costs. The container terminal (CT) of the Port of Gävle, the largest in the east coast of Sweden, is not an exception to this. With traffic growing annually, a new terminal will be opened in the following years, adding three more ship-to-shore (STS) cranes to the two existing ones, and six electric rubber tyred gantry (eRTG) cranes. Therefore, it is highly important to strengthen energy efficiency measures, reducing the energy consumption and the costs associated with it. This is why the aim of this report is to analyse whether implementing energy storage systems in the cranes of the container terminal Port of Gävle can contribute to reduce electricity costs by recovering energy when braking lowering containers, and by shaving power peaks. After a literature review of current energy recovery and storage options, this work presents three solutions: two alternatives for the current situation with two ship-to-shore (STS) cranes, and a third solution to be implemented in the three future STS cranes to be installed, which can also be beneficial for any other crane in the terminal. According to the made calculations, the three alternatives can reduce considerable energy consumption, and they are highly profitable. However, those solutions are a preliminary study and more work needs to be done to determine the exact profitability and technical system details. This work has been done in collaboration with the Port of Gävle and Yilport, the company operating the container terminal.