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Öğe Akkaya Baraj Gölünü Kirleten Kızılca Deresinin Doğal Atıksu Arıtma Yöntemiyle Arıtılması(2016) Tunçsiper, Bilal; Demirel, Sevgi[Abstract Not Available]Öğe Biogas Upgrade Techologies And Biomethane Utulization Oportunities(Mehmet Sinan Bilgili, 2022) Muratcobanoglu, Hamdi; Mert, Ruhullah Ali; Muratcobanoglu, Fatma; Gokcek, Oznur Begum; Demirel, SevgiThe increase at the waste generation and energy demand still remain as a problem to be solved. Anaerobic digestion has a great importance in the term of waste reduction and renewable energy production as a green solution. Methane content of the biogas expresses the energy content and the potential. Removing impurities like CO2 H2S siloxane etc. and increasing the methane content of the biogas is allowing biomethane for further usage. Biomethane can be used as vehicle fuel (diesel replacement), gas grid injection (natural gas replacement), usage as a raw material for ethanol, dimethlyether etc. production other than electricity and heat generation. In this study, biogas upgrade technologies like pressure swing adsorption, membrane processes, scrubbing processes, cryogenic separation and biomethane utilization opportunities in the term of in-situ and ex-situ usage have been reviewed. In addition, the potential utilization areas of biomethane and specific requirements based on biogas quality are investigated comprehensively.Öğe Biomethane enhancement using reduced graphene oxide in anaerobic digestion of municipal solid waste(Elsevier Sci Ltd, 2022) Muratcobanoglu, Hamdi; Gokcek, Oznur Begum; Muratcobanoglu, Fatma; Mert, Ruhullah Ali; Demirel, SevgiThe present research investigated the impact of reduced graphene oxide (rGO) addition on the semi-continuous anaerobic digestion of the organic fraction of municipal solid waste (OFMSW) in the range of 0.5-10 gVolatileSolid(VS)/L(reactor)day organic loading rates (OLR). Adding rGO enhanced the rate and yield of biomethane production, and the maximum biomethane increment rate was obtained as 110% at an OLR of 4.0 gVS/L(reactor)day. However, after increasing the OLR to 6 gVS/L(reactor)day, there was a dramatic decrease in biomethane production because of volatile fatty acid (VFA) accumulation. Methanotrix is the predominant archaeal genus at OLRs lower than 6 gVS/L(reactor)day in reactors (89-97%). An increment in biomethane production was associated with the higher abundance of the Methanothrix genus in the rGO-supported reactor (rG) than in the control reactor (rC).Öğe BİR PLASTİK GERİ DÖNÜŞÜM TESİSİNDE ÖN TEHLİKE ANALİZİ (PHA) İLE RİSK DEĞERLENDİRMESİ(2018) Demirel, Sevgi; Sert, NerimanAtık plastikler, dünya genelinde önemli çevre sorunları haline gelmiştir. Günümüzde hem doğal kaynaklarınkorunması hem de katı atık depolama alanlarının daha uzun süre kullanımı amacıyla geri kazanım ve geridönüşüm faaliyetleri büyük önem kazanmıştır. Bursa’da faaliyet gösteren bir geri dönüşüm firması tekstil, araba üretim, makine, kimya sanayinde oluşan,tüketim sonrası plastik atık malzemeleri geri dönüşüm amacıyla kabul etmektedir. Bu çalışmada, plastikambalajlara kontamine olmuş tehlikeli kimyasal maddelerin giderimi ve yüksek yoğunluklu polietilenmalzemeden hammadde elde etmede kullanılan iş akışları ve süreçler ortaya konulmuştur. Ayrıca plastik gerikazanım/geri dönüşüm sektöründe iş sağlığı ve güvenliği ile ilgili incelemeler yapılmış ve iş sağlığı ve güvenliğirisklerini belirlemek amacıyla Ön Tehlike Analizi (PHA) metoduyla risk değerlendirilmesi yapılmıştır.Öğe Biyohidrojen Üretimine Nanopartikül Madde İlavesinin Karanlık Fermantsayon Sürecine Etkisi ve Yaşam Döngü Analizi Yaklaşımı(2022) Çobanoğlu, Hamdi; Muratçobanoğlu, Fatma; Demirel, SevgiAtık biyokütlenin değerlendirilmesi, döngüsel biyoekonominin gelişimi için tükenen fosil kökenli yakıtlara alternatif enerji üretimi ve çevre dostu atık yönetimi yaklaşımıdır. Alternatif enerji kaynaklarından biri olan biyohidrojen enerjisi; yenilenebilir, sürdürülebilir, ucuz ve temiz enerji kaynağı olması nedeniyle uzun yıllardır araştırılan konular arasındadır. Biyokütleden karanlık fermantasyon yolu ile hidrojen eldesi ise; verimli ve temiz enerji olması nedeniyle tercih edilen başlıca proseslerden biridir. Karanlık fermantasyon yolu ile hidrojen üretim verimini artırmak amacıyla sistemlere destek sağlayan nanopartikül ilavesi ile ilgili çalışmalar son yıllarda araştırmacıların ilgi odağı olmuştur. Bu çalışmada karanlık fermantasyon ile biyohidrojen üretiminde nanaomalzeme desteğinin etkisi, ilgili mekanizmaları, kullanılan substratları ve üretim verimliliğini artırmaya yönelik yapılmış bazı çalışmalar incelenmiştir. Özellikle hem arıtımın sağlanması hem de biyohidrojen üretim tekniklerinin geliştirilmesi için kullanılan nanopartiküler malzemelerin önemine vurgu yapılmıştır. Seçilen nanomalzemenin üretim performansındaki rolünün yanı sıra ortaya çıkaracağı çevresel etkilerin de yaşam döngü analizi ile değerlendirilmesinin gerekliliği açısından ele alınmıştır.Öğe Denitrification performance and microbial community dynamics in a denitrification reactor as revealed by high-throughput sequencing(Iwa Publishing, 2017) Demirel, SevgiThe dynamics of the bacterial community associated with the denitrification process in a fixed bed column reactor (FBCR) were investigated using 454-pyrosequencing methodology. A FBCR filled with elemental sulfur and limestone was operated for about 94 days under autotrophic and mixotrophic (autotrophic + heterotrophic) conditions at 30 degrees C. Efficient simultaneous bromate and nitrate removal was achieved at feed concentrations of 500 mu g/L bromate and 45 mg/L nitrate under autotrophic and mixotrophic conditions. Operational taxonomic units-based analysis (97% similarity cut-off) of bioreactor samples (three periods) revealed that the microbial diversity changed regardless of operational conditions. Sulfurimonas spp. was dominant in the reactor at the adaptation stage. Thiobacillus denitrificans is a chemolithoautotrophic bacterium that is capable of the oxidation of inorganic sulfur compounds. After the adaptation period, the microbial profile changed such that Spirochaetacea spp. and Denitratisoma spp. were major species in the column reactor. After 60 d of operation, Hyphomicrobium vulgare became dominant due to the mixotrophic denitrification conditions.Öğe Elma posasından biyohidrojen üretimine farklı yükleme oranlarının etkisi(2023) Baş, Furkan; Çobanoğlu, Hamdi; Gökçek, Öznur Begüm; Demirel, SevgiKüresel çevre problemleri ve modern dünyanın artan enerji talebi alternatif ve yenilenebilir enerji kaynakları arayışını ortaya çıkarmıştır. Alternatif enerji kaynaklarının başında ise yüksek enerji içeriğine sahip olması, enerji taşıyıcısı olması ve çevre dostu olması gibi avantajları nedeniyle hidrojen gelmektedir. Hidrojen üretim prosesleri; elektrokimyasal yöntemler, termal yöntemler ve biyolojik hidrojen üretimi olarak sıralanabilir. Bu yöntemler arasında daha sürdürülebilir olması nedeniyle biyolojik yöntemler ön plana çıkmaktadır. Bu çalışmada, biyolojik bir proses olan karanlık fermantasyon yöntemi ile elma posasından biyohidrojen üretimi incelenmiştir. Elma posası kullanılarak, aşı çamuruna uygulanan fiziksel ön işlem (90°C- 30 dk) sonrası farklı substrat/aşı (S/I) yükleme oranlarında kesikli reaktörlerden elde edilen biyohidrojen verimleri karşılaştırılmıştır. En iyi performansı gösteren S/I 2 yükleme koşullarında uçucu katı başına (UK) 208 ml/gUK biyogaz ve 18 mlH2/gUK biyohidrojen üretimi gerçekleşmiştir. Mikrobiyal dağılım sonuçları incelendiğinde Lactobacillus, Clostridium ve Lachnospiraceae türlerinin en baskın türler olduğu görülmektedir.Öğe İLETKEN MALZEMELERİN KATI ORGANİK ATIKLARDAN BİYOGAZ ÜRETİMİNE ETKİSİ(2019) Çobanoğlu, Hamdi; Gökçek, Öznur Begüm; Demirel, SevgiAnaerobik proses (AP) ile hem atık bertarafı gerçekleşir, hem de yenilenebilir enerji kaynağı olan biyogazüretilir. Ancak, AP uzun lag fazına sahip olması ve işletme koşullarındaki değişimlere karşı hassas olması gibidezavantajlara sahiptir. Sistem stabilizasyonunun sağlanması, biyogaz üretiminin ve arıtmanın sürekliliği önemarz etmektedir. Bu durumun sağlanması için uygulanan güncel yöntemlerden biri de AP’lerin iletken malzemelerile desteklenmesidir. Bu çalışmada organik katı atıkların besin maddesi olarak kullanıldığı iletken malzemeler iledesteklenen AP ’lerin, sistem stabilizasyonu, biyogaz-biyometan üretimi ve mikrobiyal dağılım üzerindekietkileri incelenmiştir.Öğe Investigation of the effects of magnetite addition on biohydrogen production from apple pulp waste(Elsevier Sci Ltd, 2023) Gokcek, Oznur Beguem; Bas, Furkan; Muratcobanoglu, Hamdi; Demirel, SevgiAlong with advancing technologies, the interest in producing renewable hydrogen by biological methods has recently increased due to its economic and eco-friendly properties. Various pretreatment methods or additives, such as enzymes and conductive materials, applied to increase the efficiency of biohydrogen production have been recently studied. In the current research, magnetite was utilized to increase the bioactivity of hydrogenproducing microorganisms during dark fermentation (DF). In the study, reactors with a S/I ratio of 2 gVS/gVS were set up, and magnetite was added at concentrations of 0, 50, 100, and 200 mg/L. The maximum biohydrogen production of 73.59 ml/gVS was obtained at 100 mg/L magnetite addition. Biohydrogen production increased by 46 % with 100 mg/L magnetite addition. In the magnetite-supported reactor, the dominant bacterial genera were Sporolactobacillus (39 %), Clostridium (15 %), and Coprothermobacter (10 %). It was thought that the change in microbial distribution positively affected biohydrogen production with the addition of magnetite.Öğe Life cycle assessment and shrinkage properties of high performance mortars incorporating synthetic wollastonite microfibers(Emerald Group Publishing Ltd, 2023) Oz, Hatice Oznur; Gunes, Muhammet; Yucel, Hasan Erhan; Ersoy, Orkun; Sever, Yunus; Demirel, SevgiIn this study, the use of an alternative material as supplementary cementitious material was researched for the design of high-performance mortars (HPMs). Synthetic wollastonite microfibres (SWMs) were produced from calcite and quartz sand. The SWMs were then replaced at ratios of 0, 3, 6, 9 and 12% by cement weight to investigate the fresh, mechanical and shrinkage properties of HPMs. Test results showed that the mechanical and shrinkage properties of HPMs improved up to 9% inclusion of SWMs. The compressive strength, flexural strength, modulus of elasticity, fracture toughness and fracture energy of HPM incorporating 9% SWM was higher than that of the control mixture by 8.8-9.1%, 7.5-9.9%, 4.7-6.7%, 8.9-4.6% and 13.2-2.5% at 28-90 days, respectively. Similarly, the ratios for maximum drying shrinkage and average crack width were determined as 10.5% and 58.3%, respectively, at the end of 60 days. These findings were also supported by microstructural analysis. Moreover, the potential environmental impacts resulting from the production of 1 kg SWM and HPM incorporating 9% SWM were evaluated using the life cycle analysis software (LCA) SimaPro 8.5.0.0. Based on the LCA results, SWMs can be used as an alternative material to develop sustainable concrete structures.Öğe LINKAGE OF OPERATIONAL PARAMETERS AND MICROBIOME IN ANAEROBIC CO-DIGESTION WITH GRAPHITE(Yildiz Technical Univ, 2020) Demirel, Sevgi; Gokcek, Oznur Begum; Muratcobanoglu, HamdiIn terms of renewable energy sources, studies on increasing the amount of methane produced per unit feeding materials have attracted attention in recent years. Many different methods like chemical, physical, thermal, and thermochemical processes have been applied to anaerobic digesters for enhancing biogas production efficiency. Recently, besides these processes, supporting anaerobic digestion (AD) system with conductive materials like graphite, magnetite, activated carbon, etc. is one of the trend topics. In this paper, the effect of graphite on biogas/biomethane production potential was investigated for co-digestion of food waste (FW) and cow manure (CM). Additionally, the relationship between the distribution of anaerobic microbial structure and operational conditions is examined using Redundancy analysis (RDA) revealed that Clostridium could enhance to methanogenesis process through conductive materials such as graphite. These findings will improve the understanding of the mutual relationship between operational conditions and community composition in anaerobic digestion of food waste and cow manure mixture. As a result, the analysis of the correlation between microbiome and operational parameters indicated that Clostridium, Methanosaeta, and Methanosarcina, all together could enhance to methanogenesis process with the graphite supplementation.Öğe Nitrate and bromate removal by autotrophic and heterotrophic denitrification processes: batch experiments(BIOMED CENTRAL LTD, 2013) Demirel, Sevgi; Bayhan, IbrahimThe effects of various parameters on bromate reduction were tested using lab-scale batch reactors with sulfur based autotrophic and methanol based heterotrophic denitrification processes. The initial bromate (BrO3-) concentration of 100 and 500 mu g/L was completely reduced and bromide (Br-) was produced stoichiometrically from bromate in all batch reactors. In all experiments, nitrate was completely reduced to below detection limit. Kinetic studies showed that the sulfur-based autotrophic nitrate reduction rate increased with increasing initial nitrate concentration. At stoichiometrically sufficient methanol concentration as an external carbon source, nitrate and bromate were reduced to below US EPA drinking water limits in heterotrophic denitrification conditions. The methanol was completely depleted at the end of the heterotrophic operation conditions.Öğe Simultaneous Bromate and Nitrate Reduction in Water Using Sulfur-Utilizing Autotrophic and Mixotrophic Denitrification Processes in a Fixed Bed Column Reactor(WILEY-BLACKWELL, 2014) Demirel, Sevgi; Uyanik, Ibrahim; Yurtsever, Adem; Celikten, Hakan; Ucar, DenizCarcinogenic bromate (BrO3-) can be present in drinking water as a result of its formation from bromide (Br-) during ozonation. A fixed bed column reactor filled with elementel sulfur and limestone was operated for about six months under autotrophic and mixotrophic (autotrophic+heterotrophic) conditions at 30 degrees C. The reactor was operated at the hydraulic retention time (HRT) ranging from 16.5 to 10.1h at autotrophic conditions. Under mixotrophic conditions, 45mg/L NO3-N was removed completely at C/N ratio (mg CH3OH/mg NO3-N) between 0.55 and 1.66 at HRT of 10.1h. The average effluent pH was 7.8 and the sulfate concentration was lower than the Environmental Protection Agency limits at the mixotrophic stages. Efficient simultaneous BrO3- and nitrate removal was achieved at feed concentrations of 100-500 mu g/L BrO3- and 45mg/L nitrate under autotrophic and mixotrophic conditions. Effluent Br- measurements indicated that BrO3- was completely reduced without accumulation of by-products.Öğe Simultaneous fluoride and nitrate removal from drinking water using mixotrophic denitrification processes in a fixed bed column reactor(Desalination Publ, 2019) Demirel, Sevgi; Uyanik, IbrahimNitrate and fluoride are water contaminants found together in some regions where agricultural activities are widespread. The concentration of these contaminants is important since nitrate causes methemoglobinemia in infants and fluride causes dental diseases. In this study, a fixed bed column reactor was used with sulfur and limestone media to remove these contaminants under simultaneously autotrophic and heterotrophic (mixotrophic) conditions at 30 degrees C. The reactor was operated under these conditions for 125 d and 49.7 mg/L of NO3-N and 5.3 +/- 0.4 mg/L of F- were removed at 95.0 and 90.0% efficiency, respectively. Effluent pH was 7.8 and alkalinity was not exceeded 200 mg/L. Removal mechanisms of nitrate and fluoride were biological denitrification and physicochemical ( adsorption and precipitation), respectively, since batch experiments agreed that the removal mechanism of fluoride was not biological. This study showed that both NO3- and F- can be removed in one reactor under mixotrophic conditions, simultaneously.Öğe Simultaneous synergistic effects of graphite addition and co-digestion of food waste and cow manure: Biogas production and microbial community(Elsevier Sci Ltd, 2020) Muratcobanoglu, Hamdi; Gokcek, Oznur Begum; Mert, Ruhullah Ali; Zan, Recep; Demirel, SevgiThe effects of graphite on the anaerobic digestion of food waste (FW), cow manure (CM) and its mixture (FW/CM) via batch experiments under mesophilic conditions have been investigated in this study. Maximum biogas production with graphite addition for FW + 1 g/L, CM + 1.5 g/L and FW/CM + 0.75 g/L are 1128.46, 829.6 and 1471.1 mL/gVS respectively. Additionally, this study investigates the link between microbial community structure and biogas production when graphite addition of anaerobic digester was conducted. Based on 16S rRNA gene amplicon sequencing results, Aminiphilus (13-14%), Actinobaculum (13-15%) and Clostridium (12-18%) were the predominant bacterial genera in graphite-added FW, CM and FW/CM reactors, respectively. Comparatively higher biogas production of FW/CM synergistically affected by abundances of Clostridium as well as co-digestion in this anaerobic digestion setup. Methanosaeta was the most abundant methanogen in the graphite added digesters; however, the relative abundance of these genera was different.Öğe The impact of reduced graphene oxide (rGO) supplementation on cattle manure anaerobic digestion: Focusing on process performance and microbial syntrophy(Elsevier, 2021) Muratcobanoglu, Hamdi; Gokcek, Oznur Begum; Mert, Ruhullah Ali; Zan, Recep; Demirel, SevgiAt a time when there is a surge in demand for increasing renewable energy production, boosting biomethane production per unit organic matter/waste has become a big challenge and necessity. In this study, the effect of rGO addition on biomethane production from cow manure under mesophilic-batch conditions was investigated. Biomethane production was increased via rGO supplementation at appropriate concentrations. The highest biomethane production, which was 335 mL/gVS(ad) (65 % increase), was obtained by adding 20 mg/L rGO (CM20) while rGO addition slightly increased (up to 5.4 %) the CH4 content of biogas. The microbial community analysis indicated that via rGO supplementation, the dominant bacteria changed from Levilinea to Candidatus Cloacamonas and a more diverse archaeal community was formed. According to this study results, rGO supplementation could be used at biogas plants to boost renewable energy production.Öğe Türkiye’de Atık Malzemeden Yapılmış Kendiliğinden Yerleşen Harç Üretiminin Yaşam Döngüsü Analizi(Niğde Üniversitesi, 2019) Demirel, Sevgi; Öz, Hatice Öznur; Çiner, Fehiman; Güneş, MuhammetYaşam döngüsü değerlendirmesi (YDD), binaların ve inşaat malzemelerinin çevresel performansını analiz etmek için kullanılan bir yöntemdir. Betonda bağlayıcı malzeme olarak kullanılan çimento, üretimi esnasında sera gazı ortaya çıkarmaktadır. Dünya genelinde, toplam CO2 emisyonunun yaklaşık olarak %5-8’si çimento üretiminden kaynaklanmaktadır. Sera gazı emisyonlarının azaltılması amacıyla, çimentonun atık malzemelerle (uçucu kül, atık cam ve yüksek fırın cürufu vb.) ikame edilmesi giderek önem kazanmaktadır. Bu çalışmada, beşikten-kapıya (cradle to gate) yaklaşımı ile atık malzeme (camPET ve uçucu kül) kullanımının kendiliğinden yerleşen harç üretiminin çevresel performansı üzerindeki etkileri ortaya konulmuştur.
