Although the A-stage high-rate activated sludge (HRAS) process destroys some of the chemical energy present in municipal wastewater, this process has been gaining attention as a viable technology for achieving energy neutrality at water resource recovery facilities. In addition to carbon capture for energy recovery, A-stages are also being utilized upstream of shortcut biological nitrogen removal (BNR) processes as these BNR processes often require a controlled influent carbon to nitrogen ratio that is lower than required for conventional BNR processes. While there is extensive knowledge on conventional activated sludge processes, including process controllers and activated sludge models, there has been little detailed research on the carbon removal mechanisms of A-stage processes operated at solids retention times (SRT) less than about one day. The overall objective of this study was to elucidate the chemical oxygen demand (COD) removal mechanisms of short SRT activated sludge processes with a specific focus on the removal of the different COD fractions under varying operating conditions including dissolved oxygen, hydraulic retention time, temperature, and SRT. Once understood, automatic process control logic was developed with the purpose of producing the influent characteristics required for emerging shortcut BNR processes and capturing the remaining COD with the intent of redirecting it to an energy recovery process. To investigate the removal and assimilation of readily biodegradable substrate (SS), this study evaluated a respirometric method to estimate the SS and active heterotrophic biomass (XH) fractions of the raw wastewater influent and effluent of an A-stage pilot process. The influent SS values were comparable to the SS values determined using a physical-chemical method, but the effluent values did not correlate well. This led to the measurement of the heterotrophic aerobic yield coefficient and decay rate of the pilot process. The yield coefficient was estimated to be 0.79±0.02 gCOD/gCOD, which was higher than the accepted value of 0.67 g/g. It was speculated that the batch respirometry tests resulted in the aerobic storage of SS and this likely contributed to the error associated with the determination of SS and XH. Therefore, physical-chemical fractionation methods were used to determine the removal of the individual COD fractions. It was concluded that the SRT was the primary control parameter and below a 0.5 day SRT the dominate COD removal mechanisms were assimilation and oxidation of readily degradable substrate and sedimentation of particulate matter. At SRTs between 0.5-1 days, COD removal became a function of hydrolysis, as adsorption of particulate and colloidal matter was maximized but not complete because of limited adsorption sites. Once adequate adsorption sites were available, effluent quality became dependent on the efficiency of bioflocculation and solids separation. While the SRT of the pilot process could not be directly controlled because of severe biofouling issues when using in situ sensors, a MLSS-based SRT controller was successfully implemented instead. The controller was able to reduce total COD removal variation in the A-stage by 90%. This controller aslo provided the capability to provide a consistent carbon to nitrogen ratio to the downstream B-stage pilot process. To ascertain the settling, dewaterability, and digestibility of the sludge produced by the pilot A-stage process, several standardized and recently developed methods were conducted. The results from these tests indicated that the A-stage had similar dewaterability and digestibility characteristics to primary sludge with average achievable cake solids of 34.3±0.4% and average volatile solids reduction (VSR) of 82±4%. The A-stage sludge also had an average specific methane yield of 0.45±0.06 m3CH4/kgVS. These results were attributed to low extracellular polymeric substance (EPS) content. However, further research is needed to better quantify EPS and determine the effect of HRAS operating parameters on EPS production. Overall the A/B pilot study was able to capture 47% of the influent COD as waste sludge while only oxidizing 45% of the influent COD. Of the COD captured, the A-stage contributed over 70% as dry solids. Coupled with high sludge production, VSR, and methane yield the A/B process was able to generate 10-20% more biogas and 10-20% less dry solids after anaerobic digestion than a comparable single-sludge BNR process. / Ph. D.

No description available.

Biogas is of growing interest in Sweden, and a public inquiry suggested the government to set a goal of producing 10 TWh biogas in 2030 although only 2 TWh biogas was produced in Sweden in 2018 (Regeringskansliet, 2019) (Klackenberg, 2019). To achieve this optimistic goal and to meet the increased demand of biogas, new biogas production facilities needs to be built. The purpose of this report is to investigate the economic feasibility for the development of a biogas recovery process adjoined to an incineration facility in Sweden. The report first gives an overview of the largest incineration facilities in Sweden. The largest quantity of food waste was estimated in Gothenburg to be 56´744 WRQ SeU \eaU. For the economic feasibility, a conceptual facility was constructed with 169´000 ton residual waste per year of which 45´000 ton was food waste. A biogas process model was built in Excel where the biogas potential was calculated using characteristics for food waste. The annual production of liquid biogas was estimated to 43´970 MWK. The economic evaluation was based on the conceptual facility. In the baseline scenario the incomes for the process was the value of liquid biogas, 25,6 MSEK per year, a Gate-fee synergy of 5 MSEK per year and a Tax deduction synergy of 1 MSEK per year. The investment cost was estimated to 211,6 MSEK and the Operation & Maintenance cost was estimated to 6,3 MSEK per year. This resulted in an NPV of 69,5 MSEK and an IRR of 10,3% for the project, indicating a profitable investment. Three different scenarios were considered, apart from the baseline scenario, where the first excluded all synergies with the incineration facility, which generated an NPV of 2,3 MSEK. The second scenario only considered the minimal gate-fee synergy which gave an NPV of 37,8 MSEK. Finally, the third scenario where all synergies were included, and an additional investment grant was introduced gave the project an NPV of 111,8 MSEK. A sensitivity analysis was also conducted which showed that the input of food waste treated, weighted average cost of capital and potential grants had the biggest impact on the financial results. None of the results from the sensitivity analysis showed a negative NPV. / Intresset för biogas växer i Sverige och i en statlig utredning föreslogs regeringen att sätta upp ett mål att producera 10 TWh biogas 2030 (Regeringskansliet, 2019). Detta kan jämföras med 2018 då endast 2 TWh producerades (Klackenberg, 2019). För att uppnå detta optimistiska mål och för att möta den ökade efterfrågan på biogas behöver nya produktionsanläggningar byggas. Syftet med denna rapport är att undersöka de ekonomiska möjligheterna för utvecklingen av en biogasanläggning angränsad till en förbränningsanläggning i Sverige. Rapporten ger först en översikt över de största förbränningsanläggningarna som behandlar hushållsavfall i Sverige. Det uppskattades att den största mängden matavfall som går till förbränning i Sverige är i Göteborg där 56´744 ton matavfall förbränns per år. För att bestämma de ekonomiska förutsättningarna konstruerades en konceptuell anläggning som behandlar 169´000 ton restavfall per år varav 45 000 ton består av matavfall. En biogasprocess modellerades i Excel där den potentiella biogasen beräknades baserat på matavfallets karaktäristik. Slutligen uppskattades den årliga produktionen av flytande biogas till 43´970 MWh. Den ekonomiska utvärderingen baserades på den konceptuella anläggningen. I grund-scenariot bestod inkomsterna för av den flytande biogasen som motsvarade 25,6 MSEK per år, en ´gatefee´-synergi på 5 MSEK per år och en ´skatteavdrags´-synergi motsvarande 1 MSEK per år. Investeringskostnaden uppskattades till 211,6 MSEK och Operation & Maintenancekostnaderna uppskattades till 6,3 MSEK. Detta gav projektet ett nettonuvärde på 69,5 MSEK och en internränta på 10,3% vilket indikerar en lönsam investering. Vidare undersöktes även tre olika scenarier, utöver grund-scenariot, där det första utesluter alla synergier vilket gav ett nettonuvärde på 2,3 MSEK. Det andra scenariot beaktade endast den minimala ´gate-fee´-synergin vilket gav ett nettonuvärde på 37,8 MSEK. Det tredje scenariot inkluderade alla synergier samt ett investeringsbidrag vilket resulterade i ett nettonuvärde på 111,8 MSEK. En känslighetsanalys genomfördes också som visade att tillförseln av behandlat matavfall, kapitalkostnaden och potentiella investeringsbidrag hade den största påverkan på de finansiella resultaten. Inget av resultaten från känslighetsanalysen visade ett negativt nettonuvärde.

[EN] The aim of the present PhD Thesis is to define, develop and evaluate a methodology for an improved and more sustainable management of waste, in particular agricultural residues, turning them into a new source of energy and into added value products. Particular attention is paid to the use of rice straw as an energy vector and as a precursor of silica-based compounds. The recovery of energy was carried through the gasification of biomass within a Spouted Bed Reactor. An initial definition of the main physico-chemical and thermal properties of the feed was performed. The design and operational parameters of the reactor were set according to the characteristics of the biomass. Due to the particular configuration of the reactor, its fluid dynamic properties were analysed in detail in a lab scale unit. The conditions of stability of the reactor and the prevention of segregation phenomena were studied. A scaled-up unit was used for the evaluation of the reactions of gasification of the different residues. The behaviour of the system was modelled at both fluid dynamic and thermo-chemical levels with the aid of different commercial softwares. Finally, a material valorisation was performed. The extraction of silica from the ashes resulting from the thermo-chemical process was studied. Their application as adsorbent materials for the removal of nitrates in water was discussed. / [ES] El objetivo de la presente tesis doctoral es definir, desarrollar y evaluar una metodología eficiente de gestión de residuos, en particular agrícolas, para convertirlos en una nueva fuente de energía y en productos de valor añadido. Se estudia con especial atención el uso de la paja de arroz como vector energético y como precursor de productos basados en sílice. Las reacciones de recuperación energética se han llevado a cabo a través de la gasificación de la biomasa en reactores de tipo Spouted Bed. Para ello, se han definido las propiedades físico-químicas y de comportamiento térmico de los residuos estudiados. Los parámetros de diseño y operación del reactor han sido definidos de acuerdo a las características del material tratado. Debido a la particular configuración del reactor, las propiedades fluido- dinámicas del sistema se han analizado en detalle en una unidad a escala de laboratorio. En ella se han estudiado las condiciones de estabilidad del reactor y aquellas que previenen los procesos de segregación. Se ha utilizado una unidad escalada a dimensiones de planta piloto para llevar a cabo las pruebas de gasificacion de los residuos. El comportamiento del reactor se ha modelado tanto a nivel fluido dinámico como a nivel térmico mediante el uso de diversos códigos comerciales de simulación. Finalmente, se ha realizado una valorización material basada en la extracción de sílice de las cenizas resultantes del proceso de valorización térmica. Por último, se han realizado pruebas preliminares de la posible aplicación de dicha sílice en procesos de adsorción de nitratos presentes en agua. / [CA] L'objectiu de la present tesi doctoral és definir, desenvolupar i evaluar una metodologia eficient de gestió de residus, en particular agrícoles, per convertir-los en una nova font d'energia i en productes de valor afegit. S'estudia amb especial atenció l'ús de la palla d'arròs com a vector energètic i com a precursor de productes basats en sílice. Les reaccions de recuperació energètica s'han dut a terme a través de la gasificació de la biomassa en uns reactors de tipus Spouted Bed . Per això, s'han definit les propietats físico-químiques i de comportament tèrmic dels residus estudiats. Els paràmetres de disseny i operació del reactor han estat definits d'acord a les característiques del material tractat. A causa de la particular configuració del reactor, les propietats fluid - dinàmiques del sistema s'han analitzat amb detall en una unitat a escala de laboratori. S'hi han estudiat les condicions d'estabilitat del reactor i aquelles que prevenen els processos de segregació. S'ha utilitzat una unitat escalada a dimensions de planta pilot per dur a terme les proves de gasificació dels residus. El comportament del reactor s'ha modelat tant a nivell fluid dinàmic com a nivell tèrmic mitjançant l'ús de diversos codis comercials de simulació. Finalment, s'ha realitzat una valorització material basada en l'extracció de sílice de les cendres resultants del procés de valorització tèrmica. Per ùltim, s'han realitzat proves preliminars de la possible aplicació d'aquesta sílice en processos d'adsorció de nitrats presents en aigua. / Moliner Estopiñán, CE. (2016). Valorisation of Agricultural Residues [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/68495 / Premios Extraordinarios de tesis doctorales

<p><!-- --></p><p>In the wake of the economic growth of the Chinese market the past couple of decades, the energy consumption has surged. One of the biggest consequences of the increased energy consumption is a massive increase in CO₂ emission. In fact, China has overtaken the U.S. as the biggest emitter of CO₂. In light of this energy-saving technology gets more important to implement. District heating is one of the solutions used with success in parts of China where heating is required. In this paper, an energy recovery technology has been examined for two climate zones in China namely a mechanical ventilation system using a flat-plate counter-flow heat exchanger. Beijing is located in a cold zone while Hong Kong is located in a zone with hot summers and mild winters. Cooling load calculations were conducted manually using the RTS - method developed by ASHRAE and heating load calculations were conducted for Beijing using Swedish guidelines stated in BBR. Further, the energy recovery unit (VM1) that was provided by Systemair AB was tested using a rig where different outdoor conditions were simulated. This data was then used to evaluate the potential for energy recovery in a model apartment located in the two zones. As expected, significant differences were obtained when comparing the performance for the two locations.</p><p> </p> / Redan avklarad

This thesis details the ways in which energy is consumed in an existing Canadian high-rise apartment building and outlines a strategy to reduce its consumption of grid purchased energy by 90%. Grid purchased energy is targeted because the building is located in Saskatchewan where energy is predominantly generated from fossil fuels that release greenhouse gas emissions into the environment. Greenhouse gas emissions are targeted because of the growing consensus that human activities are the cause of recent global climate destabilization and the general trend towards global warming. Energy consumption is also a concern because of anticipated resource shortages resulting from increases in both global population and average per capita consumption. Many researchers are beginning to claim that a factor 10 reduction in energy use by industrialized nations will be required in order for our civilization to be sustainable.<p>The building that was studied is an 11 story seniors high-rise with a total above ground floor area of 8,351 m2. It was constructed in 1985, in Saskatoon, SK, and it is an average user of energy for this region of the world and for a building of its size and type. Numerous field measurements were taken in the building, both during this study and previously by the Saskatchewan Research Council. These measurements were used to create a computer model of the building using EE4. After the computer model of the building was created different energy saving retrofits were simulated and compared. <p>Over 40 retrofits are presented and together they reduce the annual grid purchased energy of the building from 360 kWh/m2 (based on above ground floor area) to 36 kWh/m2, a factor 10 reduction. Natural gas consumption was reduced by approximately 94% and grid purchased electrical consumption was reduced by approximately 81%. As a result of these energy savings, a factor 6.6 reduction (85%) in greenhouse gas emissions was also achieved. The goal of factor 10 could not be achieved only through energy conservation and the final design includes two solar water heating systems and grid-connected photovoltaic panels. These systems were modeled using RETScreen project analysis tools.<p>Capital cost estimates and simple payback periods for each retrofit are also presented. The total cost to retrofit the building is estimated to be $3,123,000 and the resulting utility savings from the retrofits are approximately $150,000 per year. This is a factor 6.0 reduction (83%) in annual utility costs in comparison to the base building. While the typical response to proposing a green building is that financial sacrifices are required, there is also research available stating that operating in a more sustainable manner is economically advantageous. This research project adds to the green building economics debate by detailing savings and costs for each retrofit and ranking each retrofit that was proposed. The most economically advantageous mechanical system that was added to the building was energy recovery in the outdoor ventilation air. It should also be noted that there was already a glycol run-around heat recovery system in the building and even greater savings would have been obtained from installing the energy recovery system had this not been the case.<p>While the goal of factor 10 required economically unjustifiable retrofits to be proposed, the majority of the retrofits had simple payback periods of less than 20 years (30 out of 49). This research shows that certain retrofits have highly desirable rates of return and that when making decisions regarding investing in auditing a building, improving energy efficiency, promoting conservation, or utilizing renewable energy technologies, maintaining the status quo may be economically detrimental. This would be especially true in the case of new building construction.

<!-- --> In the wake of the economic growth of the Chinese market the past couple of decades, the energy consumption has surged. One of the biggest consequences of the increased energy consumption is a massive increase in CO2 emission. In fact, China has overtaken the U.S. as the biggest emitter of CO2. In light of this energy-saving technology gets more important to implement. District heating is one of the solutions used with success in parts of China where heating is required. In this paper, an energy recovery technology has been examined for two climate zones in China namely a mechanical ventilation system using a flat-plate counter-flow heat exchanger. Beijing is located in a cold zone while Hong Kong is located in a zone with hot summers and mild winters. Cooling load calculations were conducted manually using the RTS - method developed by ASHRAE and heating load calculations were conducted for Beijing using Swedish guidelines stated in BBR. Further, the energy recovery unit (VM1) that was provided by Systemair AB was tested using a rig where different outdoor conditions were simulated. This data was then used to evaluate the potential for energy recovery in a model apartment located in the two zones. As expected, significant differences were obtained when comparing the performance for the two locations. / Redan avklarad

This thesis details the ways in which energy is consumed in an existing Canadian high-rise apartment building and outlines a strategy to reduce its consumption of grid purchased energy by 90%. Grid purchased energy is targeted because the building is located in Saskatchewan where energy is predominantly generated from fossil fuels that release greenhouse gas emissions into the environment. Greenhouse gas emissions are targeted because of the growing consensus that human activities are the cause of recent global climate destabilization and the general trend towards global warming. Energy consumption is also a concern because of anticipated resource shortages resulting from increases in both global population and average per capita consumption. Many researchers are beginning to claim that a factor 10 reduction in energy use by industrialized nations will be required in order for our civilization to be sustainable.<p>The building that was studied is an 11 story seniors high-rise with a total above ground floor area of 8,351 m2. It was constructed in 1985, in Saskatoon, SK, and it is an average user of energy for this region of the world and for a building of its size and type. Numerous field measurements were taken in the building, both during this study and previously by the Saskatchewan Research Council. These measurements were used to create a computer model of the building using EE4. After the computer model of the building was created different energy saving retrofits were simulated and compared. <p>Over 40 retrofits are presented and together they reduce the annual grid purchased energy of the building from 360 kWh/m2 (based on above ground floor area) to 36 kWh/m2, a factor 10 reduction. Natural gas consumption was reduced by approximately 94% and grid purchased electrical consumption was reduced by approximately 81%. As a result of these energy savings, a factor 6.6 reduction (85%) in greenhouse gas emissions was also achieved. The goal of factor 10 could not be achieved only through energy conservation and the final design includes two solar water heating systems and grid-connected photovoltaic panels. These systems were modeled using RETScreen project analysis tools.<p>Capital cost estimates and simple payback periods for each retrofit are also presented. The total cost to retrofit the building is estimated to be $3,123,000 and the resulting utility savings from the retrofits are approximately $150,000 per year. This is a factor 6.0 reduction (83%) in annual utility costs in comparison to the base building. While the typical response to proposing a green building is that financial sacrifices are required, there is also research available stating that operating in a more sustainable manner is economically advantageous. This research project adds to the green building economics debate by detailing savings and costs for each retrofit and ranking each retrofit that was proposed. The most economically advantageous mechanical system that was added to the building was energy recovery in the outdoor ventilation air. It should also be noted that there was already a glycol run-around heat recovery system in the building and even greater savings would have been obtained from installing the energy recovery system had this not been the case.<p>While the goal of factor 10 required economically unjustifiable retrofits to be proposed, the majority of the retrofits had simple payback periods of less than 20 years (30 out of 49). This research shows that certain retrofits have highly desirable rates of return and that when making decisions regarding investing in auditing a building, improving energy efficiency, promoting conservation, or utilizing renewable energy technologies, maintaining the status quo may be economically detrimental. This would be especially true in the case of new building construction.

The Facility Manager of a laboratory environment continuously walks a fine line between safe and economical operation of that facility. The primary responsibility of the laboratory is to provide a safe environment for personnel while optimizing the space for experiment. Energy efficiency is not a necessary goal. Laboratories typically require HVAC systems utilizing 100% outside air to protect the occupants. Facilities demanding the basic design requirement of 100% outside air can result in annual energy costs 4 to 5 times greater than that of the typical office building requiring 20 CFM per person. With energy costs typically representing a substantial part of an organizations operating budget is it prudent for facility managers to seek opportunities to reduce these costs. The intent of this research is to show that participation of a knowledgeable Facility Manager, during the initial design phase of a laboratory facility, can result in a finished product capable of easily incorporating a variety of energy efficiency technologies. The scope of this research is limited to smaller chemical laboratories supported with less than 20,000 CFM of comfort air. When the Facility Manager actively participates in the design process for laboratory environments there is potential for increased HVAC energy efficiency. A substantial portion of this research has been conducted from the authors daily experience and responsibility for a small chemical laboratory. Additional data was collected using personal interviews among industry experts and fellow colleagues working in the Atlanta metropolitan area with significant laboratory experience. This research focused on the mechanical systems supporting laboratories as they represent the largest percentage in first costs, energy consumption, and offer the greatest opportunity for energy reduction. The results of this research are intended to provide guidance to Facility Managers to incorporate cost effective energy recovery systems in either new construction or at a future date. The results of this research project the impact of energy consumption in a small chemical laboratory from the hypothetical installation of a customized energy recovery system.

Today, the investigation of fuel economy improvements in internal combustion engines (ICEs) has become the most significant research interest among the automobile manufacturers and researchers. The scarcity of natural resources, progressively increasing oil prices, carbon dioxide taxation and stringent emission regulations all make fuel economy research relevant and compelling. The enhancement of engine performance solely using incylinder techniques is proving increasingly difficult and as a consequence the concept of exhaust energy recovery has emerged as an area of considerable interest. Three main energy recovery systems have been identified that are at various stages of investigation. Vapour power bottoming cycles and turbo-compounding devices have already been applied in commercially available marine engines and automobiles. Although the fuel economy benefits are substantial, system design implications have limited their adaptation due to the additional components and the complexity of the resulting system. In this context, thermo-electric (TE) generation systems, though still in their infancy for vehicle applications have been identified as attractive, promising and solid state candidates of low complexity. The performance of these devices is limited to the relative infancy of materials investigations and module architectures. There is great potential to be explored. The initial modelling work reported in this study shows that with current materials and construction technology, thermo-electric devices could be produced to displace the alternator of the light duty vehicles, providing the fuel economy benefits of 3.9%-4.7% for passenger cars and 7.4% for passenger buses. More efficient thermo-electric materials could increase the fuel economy significantly resulting in a substantially improved business case. The dynamic behaviour of the thermo-electric generator (TEG) applied in both, main exhaust gas stream and exhaust gas recirculation (EGR) path of light duty and heavy duty engines were studied through a series of experimental and modelling programs. The analyses of the thermo-electric generation systems have highlighted the need for advanced heat exchanger design as well as the improved materials to enhance the performance of these systems. These research requirements led to the need for a systems evaluation technique typified by hardware-in-the-loop (HIL) testing method to evaluate heat exchange and materials options. HIL methods have been used during this study to estimate both the output power and the exhaust back pressure created by the device. The work has established the feasibility of a new approach to heat exchange devices for thermo-electric systems. Based on design projections and the predicted performance of new materials, the potential to match the performance of established heat recovery methods has been demonstrated.