FBE- Çevre Mühendisliği Lisansüstü Programı - Doktora
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Yazar "Altınbaş, Mahmut" ile FBE- Çevre Mühendisliği Lisansüstü Programı - Doktora'a göz atma
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ÖgeAnaerobik Biyoreaktörlerde Bütiratı Ayrıştıran Mikroorganizma Topluluklarının Popülasyon Dinamiği(Fen Bilimleri Enstitüsü, ) Altınbaş, Mahmut ; Öztürk, İzzet ; Çevre Mühendisliği ; Environmental EngineeringBütirat, organik maddenin ayrışmasında metanojenlerin mevcut olduğu havasız arıtma koşullarında önemli bir ara üründür. Havasız reaktörlerde metan üretiminin %60’a varan kısmı bütirattan kaynaklanabilir. Bu tezde sunulan çalışmanın amacı havasız biyoreaktörlerde önemli bir ara ürün olan bütiratı ayrıştıran sintrofik mikrobiyal topluluğun popülasyon dinamiğini detaylı bir şekilde ortaya çıkarmaktır. Bu kapsamda konvansiyonel kültür çalışmalarıyla birlikte kültür çalışması gerektirmeyen moleküler teknikler kullanılmıştır. Ayrıca, atıksularda yaygın olarak gözlenen sülfatın sintrofik bütirat ayrışmasına etkisi de incelenmiştir. Yukarı akışlı Havasız Çamur Yataklı (UASB) Reaktörler ve farklı inkübasyon teknikleri kullanılarak biyokütle bütirata alıştırılmış ve moleküler biyolojik teknikler ile bu biyokütlenin karakterizasyonu yapılmıştır. Sintrofik butirat ayrıştıran mikrobiyal topluluktaki türler konvansiyonel ve moleküler teknikler ile kalitatif ve kantitatif olarak belirlenmiştir. Bu teknikler, MPN: En Uygun Sayı, PCR-RFLP: Polimeraz Zincir Reaksiyonu-Restriksiyon Parça Uzunluk Polimorfizm, DGGE: Denatüre Gradyan Jel Elektroforezi, Q-PCR: Kantitatif PCR, ve SIP: Stabil İzotop İşaretlemesi’dir. Yapılan bu çalışmada bütiratı ayrıştıran topluluğun bilinen organizmalardan farklı ve çeşitliliğinin fazla olduğu bulunmuştur. Aynı zamanda bu çeşitlilik filogenetik olarak da farklı gruplara düşmektedir. Bulgular, sintrofik olarak bütiratı ayrıştıran mikrobiyal topluluğun düşünülenden daha geniş olduğunu göstermektedir. Bu sintrofik topluluğun yapısının anlaşılması atıksuların havasız arıtılmasına ışık tutmakta ve havasız prosesin geliştirilmesinde önemli bir adım olabilir.
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ÖgeMicroalgae growth in anaerobic digestate for high-value product recovery(Fen Bilimleri Enstitüsü, 2020) Ermiş, Hande ; Altınbaş, Mahmut ; 656901 ; Çevre Mühendisliği Ana Bilim DalıAs a result of diminished fossil fuel reserves and increased prices of petrochemical fuels, and the simultaneous result of fossil fuels on extreme greenhouse gas emissions leading global warming, the world is searching for an alternative renewable energy sources. Renewable energy sources such as solar, wind, hydro, geothermal and biomass have been successfully developed but research shows that biomass energy has the highest capability among other renewable sources. Microalgae has the highest attention in the field of bioenergy by not requiring arable land, their higher productivity and higher biofuel yield compared to terrestrial plants. Not only for bioenergy aspect, bu also for the environmental aspect, microalgae has too many advantages such as mitigation of CO2 through photosynthesis and treatment of wastewater. Anaerobic digestion is another and the most conventional methods used to generate energy from renewable sources. However, untreated anaerobic liquid digestate may cause eutrophication if directly discharges into the water sources due to its high nutrient content. Cultivating microalgae in digested effluents offers significant advantages in terms of wastewater treatment, the production of valuable biomass which can be further valorized, and a major decrease in the upstream cost of the process. Microalgae can assimilate nutrients especially nitrogen and phosphorous from wastewater for their growth and produce valuable biomass. Digestates include all essential macro/micro nutrients and can be recovered as cultivation media for microalgal biomass production. However, some of the main physicochemical characteristics of the digestates, such as high content of inhibitory compounds, turbidity, and colored dissolved compounds might negatively influence microalgal growth, and therefore they need to be adjusted by using one or a combination of pretreating methods (e.g., dilution, solid/ liquid separation, filtration, etc.) in order to provide suitable medium for cell growth. The main objective of this thesis was to investigate the applicability of recovery of nutrients from digestate with mixed microalgae and observe positive effect on algal biomass resulting in enhanced high value product content. High-value products such as pigments, proteins, lipids, and carbohydrates that are obtained from microalgae grown in digestate can used as fuel, fertilizer and animal feed contributing to a substantial saving in the overall cost of microalgae biomass production. In this scope, the Anaerobic Liquid Digestate (ALD) obtained from real full scale plant to demonstrate and to show the applicability of succesful growth on digestate, instead of treating with advanced treatment methods and to recover high value products from the wild type algal biomass isolated from near-by water bodies in ITU to examine its dominancy change and positive effect. To promote the sustainability of microalgae–bacteria-based systems that treat wastewater, the examination of multiple products in the form of high value products and biomass were detailly monitored. In the first part of the study, batch experiments were carried out to investigate the biokinetic coefficients for nutrient removal of mixed microalgae grown on anaerobic liquid digestate by Michaelis–Menten rate expression. The initial NH3-N concentration was varied between 18.6–87.1 mg L-1 while initial PO4-P concentration was between 1.85–6.88 mg L-1, which corresponds to 2%, 5%, 7% and 10% dilution ratio of anaerobic digestate. According to the yield results (mg chl a mg-1 nutrient), mixed microalgae uptake 10 times more nitrogen than phosphorus. Biokinetic coefficients were determined as kN = 2.48 mg NH3-N mg−1 chl a d−1, KmN = 29.3 mg L-1, YN = 0.45 mg chl a mg-1 NH3-N for nitrogen; and kP = 0.21 mg PO4-P mg−1 chl a d−1, KmP = 2.94 mg L-1, YP = 5.03 mg chl a mg−1 PO4-P for phosphorus. The highest chlorophyll production (39 mg L-1 or 3.31 mg L-1 d-1 ) was observed at the highest dilution ratio of 10%. Moreover, the highest dilution resulted in highest biomass (1.25 g L-1) despite of dark, high ammonicial and particulate rich wastewater. In the second stage of the study, mixed microalgal culture dominated by Chlorella vulgaris and Scenedesmus armatus were grown in Anaerobic Liquid Digestate (ALD) under different NaCl concentrations ranging between 0 to 100 mM. Highest lipid and carbohydrate amount were observed as 38% and 36%, respectively, when the salinity was 50 mM NaCl. However, the protein content was drastically decreased to 13% with increased NaCl concentration. Furthermore, the algal biomass was subsequently decreased along with total chlorophyll amount with increased NaCl concentration. Algal species showed diverse response to salinity stress and demonstrated a cost-effective approach towards the cultivation of mixed microalgae within digestate and provided insight that ALD and/or other wastewaters can be diluted with seawater instead of tap water in the future studies. This study could be further converted into biofuels due to high lipid increase along with the digestate treatment, which will help to valorize ALD and bring into economy. In the third stage of the study, FeSO4 supplementation ranging from 0 to 4.5 mM, and MgSO4 supplementation ranging from 0 to 5.1 mM were investigated to observe the effect on the population dynamics, biochemical composition and fatty acid content of mixed microalgae grown in Anaerobic Liquid Digestate (ALD). Overall, 3.1 mM FeSO4 addition into ALD increased the total protein content 60% and led to highest biomass (1.56 g L-1) and chlorophyll-a amount (18.7 mg L-1) produced. Meanwhile, 0.4 mM MgSO4 addition increased the total carotenoid amount 2.2 folds and slightly increased the biomass amount. According to the microbial community analysis, Diphylleia rotans, Synechocystis PCC-6803 and Chlorella sorokiniana were identified as mostly detected species after confirmation with 4 different markers. The abundance of Chlorella sorokiniana and Synechocystis PCC-6803 increased almost 2 folds both in iron and magnesium addition. On the other hand, the dominancy of Diphylleia rotans was not affected by iron addition while drastically decreased (95%) with magnesium addition. This study helps to understand how the dynamics of symbiotic life changes if macro elements are added to the ALD and reveal that microalgae can adapt to adverse environmental conditions by fostering the diversity with a positive effect on high value product. In conclusion, in this thesis, the production of microalgae biomass have been successfully carried out, and the macronutrients needed in the production of microalgae have been provided from the digestate effluent obtained from a real-scale anaerobic digester using a mixture of domestic organic solid waste, industrial treatment sludge and animal feces. Moreover, it helped to understand how the dynamics of symbiotic life changes if macro elements are added to the ALD and reveal that microalgae can adapt to adverse environmental conditions by fostering the diversity with a positive effect on high value product. This thesis might help to be a answer for aiming both reducing adverse effect of anaerobic liquid digestate by mixed microalgae and increasing product values by valorization and give an idea that digestate can be diluted with sea water instead of tap water in the future studies. Moreover, by this thesis, it was proves that digestate cultivated algae are rich source of primary (carbohydrates, proteins, lipids) and secondary (pigments) metabolites that could be exploited to produce biofuels, bio-polymers, biofertilizers, nutraceuticals, food/health grade compounds, enzymes, feed supplements etc. and the treated digestate can be reutilized for the agricultural or industrial purposes according to the high removal rates by mixed culture.