LEE- Çevre Bilimleri Mühendisliği ve Yönetimi- Yüksek Lisans
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ÖgeOtomotiv endüstrisinde iklim değişikliği kapsamında karbonsuzlaştırma fırsatlarının araştırılması(İTÜ Lisansüstü Eğitim Enstitüsü, 2025-06-17)limate change has rapidly become one of the most urgent and complex challenges of our time, demanding global, regional, and local actions across all sectors. Scientific consensus emphasizes that limiting global temperature rise to well below 2°C above pre-industrial levels is essential to mitigate catastrophic environmental and socio-economic consequences. Within this context, carbon emissions originating from industrial activities stand out as one of the primary contributors to global warming. The automotive industry, positioned at the intersection of global manufacturing and transportation, plays a pivotal role in this regard. Its carbon footprint, stemming from both direct and indirect emissions, necessitates transformative strategies to meet the evolving climate commitments. International frameworks such as the Paris Agreement and regional strategies like the European Green Deal have introduced stringent emission targets to transition toward a low-carbon economy. The Paris Agreement, ratified by 196 countries, aims to achieve climate neutrality by the second half of the 21st century. In parallel, the European Green Deal outlines the goal of making Europe the first climate-neutral continent by 2050. In line with these efforts, Turkey has committed to achieving carbon neutrality by 2053, reflecting a national-level alignment with global climate ambitions. To achieve these long-term targets, industries must adopt new paradigms in how they design operations, manage energy consumption, and embed sustainability into corporate governance. The automotive sector and its extensive supply chain, traditionally characterized by energy-intensive processes, face substantial pressure to evolve. Reducing the sector's environmental impact is no longer a matter of corporate social responsibility, but a strategic imperative driven by regulatory requirements and stakeholder expectations. The automotive industry and its supporting supply sectors consume considerable amounts of energy, primarily derived from fossil fuels. Production techniques such as injection molding, part assembly, metal treatment, and painting are notoriously energy-intensive. In many facilities, outdated equipment and legacy systems prevail, resulting in operational inefficiencies and elevated carbon emissions. One of the key issues observed across the industry is the absence of integrated energy management systems. Many plants still rely on manual tracking or decentralized systems, which leads to delays in data collection, limited analysis capabilities, and reactive rather than proactive energy strategies. Furthermore, employee awareness and engagement regarding sustainability goals remain insufficient, hampering cross-functional efforts toward environmental improvement. These systemic issues hinder the ability of companies to comply with emerging regulations, access green financing, or meet supplier sustainability criteria increasingly demanded by Original Equipment Manufacturers (OEMs). Therefore, a structured and systematic approach is required to identify root causes, develop effective countermeasures, and monitor implementation progress. In response to the challenges, this thesis employs the A3 Problem Solving Method, an established tool from the Toyota Production System (TPS). A3 is a structured methodology designed to facilitate problem identification, conduct root cause analysis, and implement practical countermeasures through a one-page report format. Despite its simplicity in format, the methodology emphasizes in-depth analysis, cross-functional dialogue, and evidence-based decision-making. The approach used in this thesis combines quantitative data analysis, process mapping, and qualitative feedback obtained from employee interviews. This triangulation ensures that both technical inefficiencies and human factors are addressed holistically. High-emission processes such as injection molding and assembly lines were prioritized, and their energy consumption patterns were closely monitored. The case study focuses on an automotive supplier operating across three distinct locations. Each site's production processes were assessed in terms of their energy use and emissions. Emissions were classified according to the Greenhouse Gas (GHG) Protocol, focusing on: Scope 1: Direct emissions from on-site fuel combustion and mobile sources; Scope 2: Indirect emissions from purchased electricity. The results revealed several critical issues: -Equipment in core processes was outdated and highly inefficient. -Energy consumption was tracked manually, limiting timely analysis. -Employee engagement in sustainability was low, and awareness programs were either insufficient or nonexistent. -These findings confirmed the need for a multidimensional intervention strategy, addressing both technical and organizational root causes. Based on the diagnosis, a comprehensive action plan was formulated, categorized into three main areas: 1. Organizational Measures Deployment of Digital Energy Management Systems: Real-time monitoring and data analytics capabilities will allow for more precise energy tracking and early anomaly detection. Implementation or Strengthening of ISO 50001: This internationally recognized standard offers a framework for continuous energy performance improvement. Adoption of the Oobeya Room Concept: Originating from lean management, Oobeya rooms promote visual management and facilitate cross-functional collaboration to drive energy-related projects. 2. Technical Measures Replacement of Hydraulic Systems: Transitioning from hydraulic to electric drives in injection molding machines can lead to significant energy savings. Retrofitting Existing Equipment: Utilizing hybrid or servo motor systems can improve process control and reduce standby energy losses. Conducting Regular Energy Audits: Audits can uncover hidden inefficiencies and prioritize investments based on return-on-energy-savings potential. 3. Training and Awareness Measures Establishment of Energy Awareness Teams: Cross-departmental groups dedicated to promoting behavioral changes and monitoring performance indicators. Capacity Building Programs: Specialized training for maintenance and engineering staff to optimize equipment settings and understand energy flows. Workshops and Internal Campaigns: Activities to strengthen sustainability culture and increase ownership at every level of the organization. The proposed interventions are aligned with multiple United Nations Sustainable Development Goals (SDGs), notably: Goal 7 – Affordable and Clean Energy, Goal 9 – Industry, Innovation, and Infrastructure, Goal 12 – Responsible Consumption and Production, and Goal 13 – Climate Action. Integrating these goals into core business functions supports not only compliance and market competitiveness but also broader environmental and societal benefits. The thesis emphasizes how operational decisions at the factory level can contribute to macro-level sustainability outcomes. Conclusion and Implications This study demonstrates that the automotive industry, despite its structural complexities and historical dependence on fossil fuels, has significant potential for decarbonization. The application of the A3 Problem Solving Method provides a replicable framework for identifying emission sources, diagnosing inefficiencies, and implementing impactful solutions. For policy makers, the findings offer valuable insights into the practical challenges and opportunities faced by industrial stakeholders. Incentive schemes, regulatory frameworks, and technical guidelines can be tailored based on such grassroots-level evidence. For industry leaders and practitioners, this research presents a practical blueprint for initiating and sustaining carbon reduction programs. Ultimately, achieving climate neutrality in the automotive sector requires not only technological advancement but also a shift in organizational mindset, strong leadership, and active employee participation. Through structured methodologies and integrated actions, the industry can play a central role in the global fight against climate change.
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ÖgeInvestigation of green buildings towards net zero carbon: example in itu ayazağa campus(ITU Graduate School, 2025-06-13)In the face of global climate change, cities have emerged as both contributors to and potential mitigators of greenhouse gas (GHG) emissions. Among urban infrastructures, buildings play a central role, accounting for 36% of carbon emissions and 40% of energy consumption within the European Union. As international frameworks such as the European Green Deal, the Fit for 55 Package, and the Energy Efficiency Directive (ordered from broader to more specific scope) push toward carbon neutrality by 2050, the building sector must undergo substantial transformation. In this context, this thesis investigates how green building certification systems, particularly LEED v3.2009, contribute to net zero carbon goals through a detailed case study of Istanbul Technical University's Department Information Technologies (throughout this thesis, BIDB will be used as the abbreviation for the Department of Information Technology, which in turn is derived from the Turkish name of the building) Building. This building, awarded LEED Platinum certification, was selected due to its data accessibility and unique energy profile. Unlike standard academic structures, it incorporates high-energy-demand server rooms, making it a critical site for understanding operational carbon emissions. The thesis follows a dual-framework methodology: first, a carbon footprint assessment in alignment with IPCC 2021 guidelines; second, a LEED-based evaluation to examine how well certification criteria align with net zero ambitions. The carbon footprint assessment follows the GHG Protocol's three scopes: Scope 1 (direct on-site emissions), Scope 2 (indirect emissions from purchased electricity), and Scope 3 (indirect emissions from supply chain activities, water, and waste). It reveals that electricity usage, primarily from server operations, accounts for over 7% of the entire campus's energy demand, contributing significantly to its carbon footprint. Emissions from building materials, notably concrete and steel, further amplify embodied carbon. Scope 1 and Scope 2 emissions were calculated using natural gas and electricity data from 2023, while Scope 3 was estimated using waste management of materials and transport data. The LEED certification evaluation investigates key credit categories and their contributions to net zero carbon objectives. Net zero carbon targets focus on reducing carbon emissions, primarily by improving energy efficiency, using renewables, or offsetting emissions. The LEED credits explicitly designed to lower carbon emissions, and sustain energy effeciency or create synergies that help with energy efficiency supports net zero goals directly or indirectly. The Energy and Atmosphere (EA) category was found to be the most directly aligned. The Minimum Energy Performance prerequisite (EAp2) and the Optimize Energy Performance credit (EAc1) support whole-building energy simulations and the prerequisite (EAp2) aims for at least a 10% improvement in energy efficiency compared to baseline standards. These criteria create a robust foundation for low-carbon building operation. On-site Renewable Energy (EAc2) directly supports carbon mitigation by incentivizing on-site generation through clean energy technologies. Measurement and Verification (EAc5) and Energy Performance Metering Path (EApc107) focus on long-term energy tracking and post-occupancy performance evaluation, both of which are critical for maintaining and verifying operational carbon reductions. The Enhanced Refrigerant Management credit (EAc4) strengthens this alignment by encouraging HVAC systems that use refrigerants with low Global Warming Potential (GWP), reducing both direct and indirect emissions associated with building operation. In contrast, the Fundamental Refrigerant Management prerequisite (EAp3) offers limited alignment. While it effectively eliminates ozone-depleting CFCs, it does not require the use of low-GWP or climate-neutral refrigerants. This limitation demonstrates that not all prerequisites within LEED are designed with net zero carbon alignment in mind. Within the Materials and Resources (MR) category, several credits provide moderate support for net zero goals. The Recycled Content credit (MRc4) encourages the use of materials with post-consumer or pre-consumer recycled content, lowering the embodied carbon associated with the extraction and processing of virgin materials. The Regional Materials credit (MRc5) promotes the use of locally sourced materials, thereby reducing transportation emissions and supporting regional supply chains. Certified Wood (MRc7) contributes by encouraging the use of wood products sourced from responsibly managed forests, which sequester carbon and reduce lifecycle environmental impacts. While the Storage and Collection of Recyclables prerequisite (MRp1) and the Construction Waste Management credit (MRc2) do not directly reduce emissions, they promote waste diversion and recycling, which indirectly support embodied carbon reduction. The Indoor Environmental Quality (EQ) and Sustainable Sites (SS) categories display a more nuanced relationship to carbon targets. Credits such as Daylight (EQc8.1) enhance visual comfort while reducing reliance on artificial lighting, thereby lowering energy demand. Heat Island Effect – Nonroof (SS) can reduce urban heat buildup, which in turn lowers cooling loads and associated emissions. However, many credits in these categories—such as Minimum IAQ Performance (EQp1) or Lighting Control (EQc6.1)—focus primarily on occupant health and satisfaction. Although these are essential elements of sustainable design, their carbon-reduction potential is secondary unless paired with energy-efficient strategies such as demand-controlled ventilation or smart lighting systems. The ITU BIDB Building's sustainable features complement its LEED certification and reflect a broader commitment to carbon-conscious design. The building is equipped with energy-efficient mechanical systems, including high-efficiency heating and cooling pumps that are optimized for performance. It includes rooftop solar panels, which currently provide approximately 3% of its annual electricity consumption, helping to offset grid-based emissions. Water conservation is achieved through advanced strategies such as smart irrigation systems, rainwater harvesting enabled by permeable concrete surfaces, and active carbon water filtration. The building also incorporates regionally sourced and recycled construction materials and employed low-impact construction practices to minimize site disturbance, dust emissions, and noise during the building phase. Despite achieving LEED Platinum status, the thesis identifies a critical gap between certification outcomes and actual operational carbon performance. Given the building's server-dense design and high electricity demand, the LEED BD+C: Data Centers rating system would have been a more appropriate choice for the design phase, as it is specifically tailored to address the intensive energy needs of data-centric facilities. Additionally, the LEED BD+C: New Construction system does not include a lifecycle-oriented framework, which limits its ability to reflect ongoing building performance. To address this limitation, a certification system capable of evaluating real operational data, such as LEED O+M (Operations and Maintenance), should be implemented to ensure continuous monitoring, emissions tracking, and alignment with net zero carbon targets over the building's full lifespan. Strategically, this thesis recommends prioritizing energy efficiency before implementing on-site renewable energy systems to maximize emission reductions. It emphasizes the need to integrate carbon accounting into LEED or comparable frameworks, adopt long-term monitoring tools like ENERGY STAR Portfolio Manager, and revise credit structures to reflect embodied carbon and lifecycle performance. Government incentives, policy alignment, and institutional frameworks that support lifecycle-based assessment are also crucial to drive meaningful decarbonization in the built environment. Additionally, stakeholder education and occupant engagement in energy-conscious behavior play an important role in bridging the gap between design intent and operational outcomes. Although this research is centered on a single case study, it presents a replicable dual-framework model that can be applied to other institutional and municipal buildings. It highlights the necessity of linking certification tools with verified carbon metrics and supports the broader transformation of green buildings from energy-efficient spaces into operationally net-zero carbon assets. In conclusion, the ITU BIDB Building case study demonstrates that while LEED certification is a powerful tool for sustainable construction, its current framework must evolve to better address operational and embodied carbon. Aligning certification systems with the rigor of GHG protocol-based carbon accounting and lifecycle performance tracking is critical for cities and campuses that are actively pursuing net zero carbon targets. This thesis offers not only a building-level analysis but also a framework for future policy development, institutional planning, and academic discourse in the field of sustainable architecture and urban development.
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ÖgeAnaerobic processing of and nutrient recovery from source separated human urine(Graduate School, 2019-06-12)Due to the increase in world population which is around 7.7 billion in early 2019 and it was estimated to increase to 9.0 billion by 2050, the stress on the available resources of water, food, energy, etc. increases as well. This enormous increase in world population will put the mankind under a critical challenge related to resource security. Part of the Millennium Development Goals as well as Sustainable Development Goals are to reduce the degradation and provide a sustainable environment that the current and next generation can live in with an adequate and healthy resources to insure the prosperity of mankind. To meet the increasing needs for resources, the needs for solutions to overcome resource depletion had been increased too, and alternative resources must be found beside those that exists to maintain permanence and sustainability of these resources. It was assessed that the need for food, water and energy will show an increase of 35, 40 and 50% respectively, owning to that increasing demand of the increased number in world population by 2030 which will be 8.3 billion. Ecological Sanitation or shortly named ECOSAN is a new management concept for domestic wastewater that based on separation at source of generation. According to ECOSAN approach, domestic wastewater can be divided into three streams as grey water (all wastewater generated in household except that one originating from toilets), yellow water (human urine) and brown water (mainly feces and flush water). Human urine is known as a nutrient rich solution, and highly saline with quite considerable amount of organic matter. Human urine consist of 80% nitrogen, over 50% of phosphorus and potassium. Separation of human urine from the rest of the domestic wastewater will enable closing the nutrient loops in domestic wastewater. Several pieces in the literature studied the possibility of recovering nutrient from source separated human urine using different processes. Struvite precipitation, stripping absorption and ion exchange/adsorption are among the available processes studied in the literature. Ion exchange is one of these processes that showed a remarkable recovery of nitrogen, phosphorus and potassium from source separated urine. The studies about the organic matter fate in source separated human urine after employing ion exchange for removal/recovery of nutrients was not reported yet in the literature. This work is aiming to investigate the removal of organic matter from the liquid residue of ion exchange process using fixed bed clinoptilolite columns by suggesting the use of anaerobic process. Different configurations based on the combination between ion exchange and anaerobic processes was investigated to achieve the best results of concurrent nutrient and energy recovery. Part of the investigation is the adaptation of anaerobic granular sludge that was brought form confectionery wastewater treatment plant to a highly saline solution like urine. Natural fresh and mainly stored urine were used in this work. This work investigated the possibilities of ammonium release from anaerobic processes and its effect on the selection of the experiment configurations. Fixed bed clinoptilolite column was used for ion exchange process and Expanded Granular Sludge Bed (EGSB) reactor was used for anaerobic process. Human urine was collected from separation system the separates urine from men's toilet at the Department of Environmental Engineering in Istanbul Technical University. The results revealed that the adaptation of anaerobic granular sludge was successful under very diluted fresh urine solution in the feeding with COD removal efficiency of 75%. While under higher fresh urine concentration in the feeding the COD removal reduced to reach 40% with 65% fresh urine. The release of ammonium was monitored at the adaptation with fresh urine and it was observed that the percent of release was not appreciable with maximum of 6% release only. The poor performance of anaerobic sludge adaptation using fresh urine as its feeding solution was attributed to the increased level of ammonium and salinity. Urine was stored to increase the amount of ammonium as urea in human urine will hydrolyze during storage. The results from urine storage were in line with previous studies specifically in terms of nutrient concentration, pH and electrical conductivity. During this work a considerable reduction of COD concentration was observed through long storage period of about 4 months that counted for almost 65% of COD reduction from its initial state. This observation was not reported by any of the previous studies used natural stored human urine. COD reduction through storage has an important impact on anaerobic processes as the amount of organic matter in the feed is expected to be lower. On the other hand, the reduced COD concentration will be beneficial for protection of the environment. After hydrolysis was completed, clinoptilolite was used to concentrate nutrients from the stored urine through ion exchange process. The results from this stage was in line with previous studies used ion exchange to remove and recover nutrients from human urine. 80% removal of ammonium from liquid phase was obtained with 99% and 70% of removal for phosphorus and potassium, respectively. It was observed that COD was removed during ion exchange process with a removal efficiency of 25 – 35%. This observation has an influence on the use of anaerobic processing for removing organic matter from the liquid residue of ion exchange process, in which lesser amount of organic matter will be present in the feeding solution. Stored urine in which nutrients had been removed then was used as a feeding for the EGSB reactor. COD removal efficiency was ranged between 60 – 85%. Under 50% stored urine in the feeding solution COD removal was observed to be the best with 85%. Regarding the use of 100% stored urine in the feeding the removal efficiency was reduced to 60%. Through these stages the salinity level had a major impact on COD removal efficiency. The quality of the EGSB reactors with stored urine as a feeding solution was evaluated for the sack of environmental protection in case the effluent was discharged without further treatment. The results revealed that the effluent of EGSB was still has a considerable amount of nutrients and COD, thus ion exchange employed with stage wise manner and variable initial loadings. The results of the stage wise operation aid to reduce ammonium, phosphorus and COD considerably that the discharge of the effluent to sewer may be possible. About biogas production up on COD removal from human urine, the results were theoretically appreciable and observable with gas counter. Methane was evolved with a range of 0.3 – 0.8 l CH4/day that corresponds to 0.19 – 0.5 l CH4/ l of urine. The effect of salinity on COD removal using anaerobic process was investigated also in this work. Synthetic solution was used to simulate stored urine that was subjected to single stage ion exchange. Synthetic urine was used to create a controlled condition regarding salinity. The results of this experiment indicated that salinity had a considerable negative impact on anaerobic process at high level like 32000 µS/cm. COD removal efficiencies were ranged between 40 – 90% with salinity level between 32000 – 10000 µS/cm. This work suggest that more effort should focus on adjusting the recommended salinity inhibition threshold in the literature. This work shows that the combination between ion exchange and anaerobic processes is possible and nutrients recovery with organic matter removal is achievable, but factors like adaptation, dilution, storage period, best operational conditions, inhibition from salinity and ammonium must be taken in consideration. This study recommends the combination of ion exchange and anaerobic process in the manner that nutrients will be removed at the first place with single stage ion exchange followed by anaerobic processes, then stage wise operation of ion exchange to improve the effluent quality form environmental protection. Recovery experiment were conducted under two different contact times, 5 and 300 min in an attempt to mimic two different irrigation type. The results revealed that most of the nitrogen and phosphorus could be recovered from the clinoptilolite surface. The results were in line with previous studies. COD was not recovered from the clinoptilolite surface. Potassium was recovered with a very limited percentage which is in contrast to previous research that reported no potassium recovery at all. Plant experiments conducted to show the effectiveness of nutrient enriched clinoptilolite as a fertilizer using pepper and tomato. The results showed that clinoptilolite had a considerable performance as a n alternative fertilizer compared to synthetic fertilizer that was tested in the same experiment. Plant height, texture and no of fruits that indicate possible fruits in clinoptilolite pots were higher than that one of synthetic fertilizer.
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ÖgeToplama ve taşıma maliyet esaslı katı atık aktarma merkezi gerekliliğinin ve uygun konumunun belirlenmesi(Fen Bilimleri Enstitüsü, 2017-12-27)Halk arasında yaygın kullanımı ile çöp toplama hizmeti belediyelerce verilen, su temininden sonra en temel hizmet olarak öne çıkmaktadır. Halk tarafından basitçe çöp toplama olarak adlandırılan iş geri planda büyük planlamalar, fizibiliteler ve maliyetler barındırmaktadır. Genel olarak bakıldığında atıkların toplanması, transfer istasyonuna götürülmesi, transfer istasyonundan da daha büyük kasalı araçlara bertaraf tesisine taşınması ve burada bertarafının sağlanması iş kalemleri bulunmaktadır. Bu işlemler arasında transfer istasyonu baypas edilerek, atıklar toplandıktan sonra doğrudan da bertaraf tesisine götürülebilmektedir. Bir atık yönetimi içerisindeki en büyük maliyeti oluşturan toplama ve taşıma aşamalarındaki maliyet alt kırılımlarına göre bu duruma karar verilmektedir. Ülkemizde çevre bilincinin gelişmesi ile katı atık düzenli depolama tesislerinin sayısı da giderek artmıştır. Bu sayede yerleşim yerlerinde oluşan katı atıkların bir mühendislik çözümü çerçevesinde sızdırmaz bir zemin üzerinde çevreye ve doğaya minimum zarar verilecek şekilde bertaraf edilmeleri sağlanmaktadır.Depolamanın yanı sıra kompost ve geri kazanım tesisleri de çok sık rastlanmamakla birlikte karşılaşılan bertaraf tesisleri arasında yer almaktadır. Artmakta olan bu tesislerin amacına hizmet edebilmeleri için katı atıkların düzenli olarak bu tesislere yönlendiriliyor olması gerekmektedir. Öbür taraftan, yerleşim yerlerindeki sokağa çıkartılan atıkların da fazla bekletilmeden alınması gerekmektedir ki, şehirlerde hastalıklar yayılmasın, kemirgenler ve haşereler üremesin. Ek olarak, atıklarını zamanında toplayarak; çevrenin temiz, derli ve toplu gözükmesini sağlayan hizmetler belediyeler için her dönemde iyi bir referans olmuştur. Süre yönetiminin bu kadar önemli olduğu bir işte vatandaşların günlük ürettikleri atık miktarları baz alınarak, uygun araç büyüklükleri ve doğru taşıma mesafeleri belirlenmelidir. Ayrıca sokakların darlığı, atık kompozisyonları, atık yoğunlukları ve yollardaki eğimler de araç tipini ve kasa hacmini belirlenmesini sağlayacak diğer etmenlerdir. Bu tez çalışması ile 7+1 m3, 13+1,5 m3, 15+1,5 m3 ve 20+1,5 m3 kasa hacimli atık toplama araçlarından her biri için, bir günde toplayabildikleri atık miktarları ve yapabildikleri toplam sefer sayıları bulunmuştur. Bununla birlikte ilgili yerleşim yerlerindeki günlük atık üretim miktarlarına göre de gerekli olabilecek araç sayıları belirlenmiştir. Çalışmanın temelinde ise tüm ebatlara ve oluşan atık miktarlarına göre oluşan maliyetlerin, farklı mesafelerdeki aktarma merkezlerine taşınması sırasında gösterdiği değişikliklerin hesap edilmesi yer almaktadır. İkinci etapta, aktarma tesisinin ilk yatırım ve işletme maliyetlerinin hesaplanması yapılmıştır. Gerek araç maliyeti hesaplamaları, gerekse de transfer istasyonu maliyetlerinin hepsi toplamda 30 yıl proje süresi gözetilerek yapılmıştır. Bu sğreye göre de yıllık amortisman maliyetleri çıkartılmış olup, bir sonraki aşamada da ton başına birim fiyatlar yerleşim yerinde günlük üretilen atık miktarları ışığında hesaplanmıştır. Üçüncü olarak ise taşıma araçları için bir optimizasyon hesaplamasına gidilmiştir. Bu sefer 40 m3, 55 m3, 70 m3 semi treyler araçlara göre bir kıyaslama yapılması planlanmıştır. Fakat istiap haddi sınırına takılan bu seçeneklerde, kasa hacmi büyüdükçe ağırlığının da artması sebebiyle, atık alınabilecek tonajın giderek düştüğü gözlemlenmiştir ve bu da maliyetleri ciddi olarak etkilemiştir. Ayrıca sahada çalışan insanların tecrübelerine dayanılarak da manevra kabiliyetlerinin düşük olduğu ve transfer istasyonları içerisinde büyük zorluklar çıkardıkları belirtilmiştir. Bu sebeple taşıma kısmı için hesaplamalar sadece 40 m3 hacimli semi treylerli için yapılmış olup, farklı uzaklık mesafelerine göre tur süreleri, günde taşıyabilecekleri atık miktarları ve maliyetleri hesaplanmıştır. Son olarak; eğer hiç transfer istasyonu olmasa, toplama araçları ile aynı zamanda taşıma işlemi de yaplsaydı, maliyetlerin nasıl oluşacağı yönünde bir çalışma yapılmış olup, tranasfer istasyonu mevcut iken kullanılan mesafe senaryolarının aynıları uygulanmıştır. Sonuç olarak; bir abak oluşturulmuş olup hangi mesafelerde ve atık miktarlarında olunduğunun seçilmesi ile birlikte aktarma merkezi kurmanın maliyet bakımından avantajlı mı yoksa dezavantajlı mı olacağına karar verilebilecektir. Bu sayede en uygun bütçenin ayrılmasıyla bir karar verilebiliyor olacak ve ciddi tasarruf sağlayacak bir kontrol mekanizması olmuş olacak.
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ÖgeLife cycle assessment of anaerobic digestion for the organic fraction of municipal solid waste(Graduate School, 2024-07-27)An increase in the quantity of generated municipal solid waste (MSW) compel societies to implement coordinated waste management plans. At the same time, municipal waste's composition diversifies in tandem with increased volumes. Plastic, paper, metal, glass, food and green waste are the main constituents of comingled waste generated by people on daily basis. Among all types, the biggest portion belongs to organics which are carbon-based materials. With a designed process, organic waste can generate energy through methanisation biologically. The process called anaerobic digestion, is one of commonly used methods to managing organic waste in a sustainable manner. On contrary, other alternative management ways such as landfilling or incineration offers more linear solutions that valuable parts of the organics (methane) are nearly wasted. In Türkiye; along 2022, according to Turkish Statistical Institute, 61% of collected municipal solid waste is mostly disposed in landfill sites. Due to commingled collection, organic fraction is mixed with other type of wastes and therefore disposed off without efficient recovery. However, a circular mindset necessitates considering waste to be handled as a source. Far from disposing organics as waste; partial recovery even like collecting landfill gas, is not adequate when the potential is considered. As a matter of fact, countries are setting targets about landfill diversion in recent years. Sustainable management for the organic fraction of municipal solid waste (OFMSW) need to be a top concern for relevant authorities. Anaerobic digestion can be considered one of the suitable methods. Principally, it imitates the natural decomposition procedure in an engineered systematic process. It produces energy with the help of microorganisms in controlled conditions. In Türkiye nearly half of the MSW collected comprise organics which have considerable potential for energy generation. The scope of this study comprises organic waste management in one of the biggest cities in Türkiye. With its more than one million populations, Sakarya generates 1500-ton municipal solid waste per day. The whole collected waste is transferred to Sakarya Integrated Solid Waste Management Plant (SEKAY). From mentioned mixed waste, every day nearly 300 tons of organics are separated through mechanical separation units in the facility. In addition to those, external organics such as waste from recreational, agricultural activities, chicken manure or waste sludge, expired foods etc. are fed to three anaerobic digesters of the plant. Mentioned organics are degraded by various microorganism groups then nutrient-rich digestate and energy-rich biogas are produced without elemental oxygen. Released methane gas is collected via pipelines and stored in the gas balloon. As the main target is producing electricity, whole process is ended in gas engines where electricity is generated and transferred to the city grid. Heat is also another outcome of the process. Due to certain temperature needs of biological activities, the digesters are externally heated with the heat produced at the facility. The study's entire set of data is obtained from SEKAY's one-year interval anaerobic digestion operations from April 2022 to April 2023. According to records, an average of 300 tons of organic is fed into digesters and 112 MW of electricity is produced per day. The objective of this study is to evaluate the environmental sustainability of the anaerobic digestion process with a life cycle approach. The life cycle assessment (LCA) can be defined as a software-based process modeling tool. The method uses all material and energy input-output data to compile possible environmental impacts of the system. In this study, all calculations and analyses are done corresponding to a functional unit which is 1 kWh of electricity produced in SEKAY. The environmental burdens of producing 1 kWh of electricity from OFMSW are analyzed with Gabi software which has the standard framework presented in ISO 14040/14044. Every resource and emission is allocated to one or more of the impact categories included in the assessment. Thus, by utilizing the CML (Centre of Environmental Science at Leiden University) 2001 method, this study focused on impact categories of global warming potential (GWP), ADP abiotic depletion potential-elements (ADP elements), abiotic depletion potential-fossil (ADP fossil), acidification potential (AP), eutrophication potential (EP), human toxicity potential (HTP), marine aquatic ecotoxicity potential (MAEP), ozone depletion potential (ODP), terrestrial ecotoxicity potential (TETP), freshwater aquatic ecotoxicity potential (FAETP), human toxicity potential (HTP), photochemical ozone creation potential (POCP). Eventually, ideas having waste to energy technologies circle around escalating obligatory waste management issues into another sustainability level. Not to have 'more trouble than it's worth' situation; precautions must be taken by authorities. Therefore, the process's environmental burdens should primarily be assessed and addressed appropriately. To conclude, the present study was designed to identify the impacts of anaerobic digestion of OFMSW with the aim of providing both environmental and technical opportunities to waste management sector. Results attained from LCA of anaerobic digestion (AD) study indicate that the biggest burden is attributed to the combined heat and power (CHP) unit. Whereas operational activities have higher impacts cumulatively, construction of the AD plant, CHP unit, composting facility has a significant effect which increases the total influence of organic fraction of municipal solid waste (OFMSW) management. Once the specifics are examined, electricity consumption on various points of the AD process has a noticeable negative environmental impact due to national grid content. In this manner, it is deemed necessary to conduct further sensitivity analysis which includes different electricity sources: national grid, bioenergy and solar. The results revealed that the least environmentally friendly source is the national grid due to its yet insufficient renewable source content. By taking into consideration of facility's real situation and future possibilities, storing liquid digestate in specially constructed lagoons and purifying (upgrading) biogas scenarios are also assessed.