M.S. Theses

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Assessment of eukaryotic diversity around Robert Island in Antarctica by metabarcoding
(Thesis (M.S.) - Bogazici University. Institute of Environmental Sciences, 2022., 2022) Tarhana, Yağmur.; Bilgin, Raşit.
The rapid growth of human population and overuse of natural resources lead to the deterioration of the balance of ecosystems. Disruption of the environment adversely affects biodiversity and can even cause species extinctions. Since the traditional species detection methods can be expensive and time-consuming, a new, cost-effective, and environmental- friendly method has emerged as an alternative. The new environmental-DNA (eDNA) metabarcoding method is based on DNA isolation, amplification of barcode region, and sequencing of samples taken from environmental systems followed by data analysis for taxonomic assignment. In this study, water samples were collected around Robert Island in Antarctica as a part of the second Turkish Antarctic Expedition (TAE-II) in 2018 to monitor species diversity. Then, mitochondrial cytochrome oxidase I (COI) barcode regions were amplified and sequenced on Illumina platform. Sequences were formatted via OBITools, aligned with BLAST+, and compared with three reference databases (MIDORI, WoRMS, and GenBank) for taxonomic assignment. A total of 39 taxa were found, of which 18 were identified as animal species, but most of the species were algae. Identifying only one taxon in common in the three databases revealed the inconsistency between the reference databases. Additionally, 166 OTUs in MIDORI and 179 OTUs in WoRMS and GenBank databases remained unidentified, indicating that they are deficient in terms of the reference sequence information of taxa found in Antarctica. We conclude that various methods and databases should be used in tandem for biodiversity characterization via metabarcoding in order to increase accuracy and capture species diversity, at least in Antarctica.
Environmental sustainability analysis of renewable energy generation with photovoltaic solar panels in Turkey
(Thesis (M.S.) - Bogazici University. Institute of Environmental Sciences, 2022., 2022) Solmaz, Zehra.; Cılız, Nilgün.
Life Cycle Assessment is a method that scrutinizes in detail the toxic environmental effects of products and services over their entire life span. The aim of this study is to reveal the environmental effects of solar panels, which are accepted as the cleanest method of obtaining energy, throughout their life cycle and to present a more sustainable solar energy generation roadmap. For this reason, multi-Si PV solar panel type, which is the most widely used type and dominates the world market, has been studied. Environmental impact categories were assessed using GaBi 9.5 Software, EcoInvent Database and CML Assessment Methodology. While evaluating the life cycle of the multi Si PV panel, metallurgical silicon smelting, solar grade multi-Si purification, wafer slicing, ingot casting, cell processing, panel assembly, transportations and recycling stages were studied. In addition, three different recycling scenarios, which diverge according to delamination methods, were also examined in terms of their environmental effects. Thus, a framework has been put forward on how the toxic effects of solar panels at the end of their life can be minimized. In this research, both real sector data and literature data were used. The multisilicon production process, which consists of the stages of metallurgical silicon smelting and solar grade multi- Si purification, and module assembly stage emerged as the two processes that cause the most environmental impact. In recycling scenarios, the FRELP2 process, which is a combination of thermal and chemical delamination processes, provided the best results in terms of environmental impact.
Climate change induced water scarcity risk mapping : coupling of multi criteria decision analysis with analytic hierarchy process methods
(Thesis (M.S.) - Bogazici University. Institute of Environmental Sciences, 2022., 2022) Ödensoy, Sena.; Güven, Başak.
Water resources have a vital importance for all living beings, ecosystems and ecological cycles. However, only less than 1% of water on Earth is available for human consumption. The impacts of human activities on water resources, both in quantitative and qualitative aspects, have been widely discussed and studied by many researchers for years. Meantime, global climate crise emerged by the cumulative impacts of anthropogenic activities. Impacts of climate change have been widely observed either as extreme precipitation events causing floods, or heatwaves causing droughts and wildfires. Research also demonstrates high confidence about the future climate change impacts on water resources. Especially, Mediterranean region has been pointed out as one of the regions that will be facing severe drought risk. This study aims to perform climate change induced water scarcity risk mapping by including climatic, geographical, socio-economic and infrastructural parameters. Büyük Menderes Basin was selected as the case study area due to its location and the intensity of agricultural activities involved in the basin. MCDA-AHP method was utilized with the coupling of QGIS and Fuzzy membership methods. Publicly available data were used to identify spatial water scarcity risks in the Basin. SSP1-1.9, SSP3-2.6 and SSP5-8.5 scenarios were used to identify subbasins with the highest water scarcity risk for 2050. Comparison of parameters causing water scarcity risk is seen as the main output of the study. It should be noted that this study suggests a tool, rather than a full risk assessment to be used as a guidance for policy makers.
Transforming the food system through food security and food sovereignty : comparing the food policies of Istanbul and Izmir metropolitan municipalities in Turkey
(Thesis (M.S.) - Bogazici University. Institute of Environmental Sciences, 2022., 2022) Gerçek, Gökçe Pınar.; Ertör Akyazı, Pınar.
Urbanization, industrialization, globalization, and the climate crisis are leading to alarming rates of food insecurity within urban contexts, increasing social and ecological inequities. Cities are assuming a leading role in agri-food policymaking due to their potential to offer place-based and targeted solutions and create new spaces for participation. In this context, food security and food sovereignty concepts are increasingly referred to, however, to date, there are only few studies comparing municipal governments’ role in urban food policy making and their transformative potential based on the frameworks of food security and food sovereignty. This study aims to contribute to critical food studies by investigating urban food policies of Istanbul and Izmir Metropolitan Municipalities in Turkey. Based on in-depth interviews with representatives from these two municipalities, producer and consumer cooperatives, scholar-activists, a review of formal municipal documents and participant observation methods, the present study identifies commonalities and differences relevant for the transformation of the food policies in these two cities from the perspective of food security and food sovereignty. The results demonstrate that urban food policies in Istanbul and Izmir mainly focus on small-scale farmer supports and increasing food security of their residents, while the degree of adoption of main food sovereignty principles varies. The findings reveal that even though there are substantial efforts towards more progressive food policy making, both cities are in need of more comprehensive and integrated approaches enabling participation of different stakeholders to operationalize food security and food sovereignty.
Green road project from an environmental justice perspective : stakeholders, alternatives and conflicts
(Thesis (M.S.) - Bogazici University. Institute of Environmental Sciences, 2022., 2022) Öztürk, Öykü.; Aydın, Cem İskender.
There is a two-way interaction between tourism and environment. On the one hand, many forms of tourism depend on the environment and natural beauties in order to sustain themselves and use the nature as the main resource in many aspects; and on the other hand, it has drastic negative impacts on the environment both in terms of land and resource use, waste generation, and carbon emissions. In general, these adverse impacts are not taken into consideration properly when tourism policies are formulated, or they are even ignored on purpose in many instances and nature is sacrificed in favor of economic benefits, causing many socio-environmental conflicts around the world. At this background, this thesis assesses the socio-environmental conflict around the Eastern Black Sea Green Road Project and aims to reveal the attitudes of the stakeholders in the region. The Green Road Project was developed as a solution to the difficult and unsafe transportation problem between the plateaus and is put forward by DOKA (Eastern Black Sea Development Agency) as connecting “…the important plateaus and tourism centers of eight provinces and [allowing] domestic and foreign tourists coming to the region to travel along the determined route in an improved physical structure" (DOKAP, p.24, 2016). This thesis reveals that national tourism policies and implementations focus rather on the economic dimension and mostly ignoring ecological distribution and the procedural justice issues. This in turn causes local level ecological distribution conflicts and prevents an encompassing, just, and sustainable tourism practice.
Detection and identification of anaerobic microorganisms biochemically degrading lignin in İğneada floodplain forest
(Thesis (M.S.) - Bogazici University. Institute of Environmental Sciences, 2022., 2022) Özsefil, İbrahim Cem.; İnce, Bahar Kasapgil.
Lignocellulosic biomass, which is found in large amounts in nature and a significant part of it is considered as waste, is seen as one of the most promising source for green and renewable energy for various reasons. However, lignin prevents the lignocellulosic material from reaching its potential due to its recalcitrant structure. The anaerobic digestion of lignin by microorganisms seems to be the most viable option to overcome this obstacle. The aim of this thesis is to discover anaerobic microorganisms that can digest lignin from sediment and dune samples taken from two different regions (Hamam Lake and Bulanık Stream) of the İğneada floodplain forest in northwest Turkiye. Samples were enriched with alkaline lignin as a sole carbon source at 37oC with three incubation periods lasting a total of 150 days. Then, DNA of the samples was isolated and sequenced metagenomically by MinION. In addition, various physicochemical analyzes including biogas production, pH, gas composition, VFA production, VS removal, determination of lignin content were carried out to detect how the microbial community operates during the experiments. As a result of the thesis, the degradability capacity of lignin in an oxygen-free environment has been demonstrated by various parameters for both stations. According to metagenomic data, it was determined that some microbial phyla and species, in which the microbial community changed as the transfers progressed, became dominant. Consequently, microbial community members that may be responsible for lignin digestion have also been identified.
Integrated wastewater management for sustainable agriculture operations using cyanobacteria
(Thesis (M.S.) - Bogazici University. Institute of Environmental Sciences, 2022., 2022) Hocaoğlu, Dila.; Haznedaroğlu, Berat Z.
Continuous rise in world population causes higher demands for food and agricultural resources in an unsustainable way. To ensure growth and access to safe food now and meet demands in future, sustainable and economically feasible measures are needed urgently. One of the major problems in agricultural operations is management of wastewater. Despite the enriched nutrient and embedded energy contents of agricultural wastewater, environmentally sound and economically feasible methods to reuse these sources are still not at desired levels. In this thesis research, cyanobacteria A. maxima was cultivated in chitosan pretreated manure wastewater in custom- made photobioreactors. With pretreatment, total nitrogen, total phosphorus, and chemical oxygen demand were removed by 84.8%, 92.7%, 64.1%, respectively, and with cyanobacteria by 14.6%, 5.6%, 28.8%, respectively. Overall removal of 99.4% of total nitrogen, 98.1% of total phosphorus, and 92.9% of chemical oxygen demand were achieved. For comprehensive evaluation of biofertilizer use of biomass, protein, carbohydrate, lipid, fatty acid methyl esters, vitamins, amino acids, and elemental composition were analyzed. Biomass had protein content of 41.8%, total carbohydrate of 27.3% and total lipid of 24.1%. Biomass also had significantly higher amounts of B vitamins and considerable amounts of free and bound amino acids, some of which are key indicators of biostimulant presence. The study aimed to evaluate the use of cyanobacteria for wastewater treatment and harvested biomass as biofertilizer for farm applications. Overall aim was to suggest a sustainable livestock and farm management option that can manage its waste and resources in a sustainable and economically feasible way.
Effects of microwave, H2O2, S2O82-, MW/H2O2 and MW/S2O82- pre-treatments on biochemical methane production potential of the sewage sludges
(Thesis (M.S.) - Bogazici University. Institute of Environmental Sciences, 2016., 2016.) Özön, Ece.; Erdinçler, Ayşen.
The considerable increase in the sewage sludge production in wastewater treatment plants becomes a serious problem for a modern society. The treatment of excess sewage sludge is a significant issue. Many different methods and pre-treatment techniques can be applied for the stabilization of the sludge and enhancement of energy production from the sludge. This study investigated the effects of sludge pre-treatments (microwave (MW), H2O2, S2O82-, MW/H2O2 and MW/S2O82-) and also the presence of antibiotics on anaerobic stabilization and biochemical methane production potential of sewage sludges. The pre-treatments applied to sludge samples prior to anaerobic digestion speeded up the hydrolysis step and improved the biodegradability of the organics by increasing their solubility. Application of MW, H2O2 and combined MW/H2O2 (1 g H2O2/g TS (total solids)) pre-treatments increased the methane yields by 65.5%, 20% and 40%, providing 626 mL CH4/g VS, 453 mL CH4/g VS and 529 mL CH4/g VS methane yields, respectively. However, persulfate pre-treatment (1 g S2O82-/g TS) decreased the biogas production and eliminated the methane production due to inhibiting effect of the S2O82- dose on the survival of the methanogenic bacteria. The presence of antibiotics (1 mg CIP/g TS) in sewage sludge samples decreased methane yields in the anaerobic digestion process. The methane yield, obtained in antibiotic contaminated sludge containing reactor, decreased 22% to 275 mL CH4/g VS, while uncontaminated sludge containing control reactor had a methane yield of 352 mL CH4/g VS. The presence of antibiotic in sewage sludge did not show negative effect on the sludge stabilization.
Decision making tools in the production systems of personal care products
(Thesis (M.S.) - Bogazici University. Institute of Environmental Sciences, 2016., 2016.) Temizel, Şila.; Cılız, Nilgün.
Life Cycle Assessment is a method of analyzing the environmental impact of products and services that considers their full life cycle. The goal of this study is to evaluate the ecological footprints and integrate results with ecolabelling approach for selected products. The product and the consumer use data were collected from industry. Environmental impacts of different formulations were conducted by using GaBi 6.0 Software, EcoInvent Database and CML Assessment Methodology. In this study the stages were selected as raw material acquisition, manufacturing, distribution, consumer use and disposal. Additional scenarios were applied to both products to assess the environmental performance improvements. Global warming, acidification, eutrophication, ozone layer depletion and photochemical ozone creation potentials were considered for both hair conditioner and oil spray products. Overall normalized environmental impacts were also assessed. The results of the study demonstrated that, for hair conditioner life cycle, the highest potential impacts for almost all of the impact categories resulted from consumption stage. In addition, for oil spray, the raw materials acquisition stage has the highest impact in overall life cycle. In the comparison of these two products, environmental impact potential of oil spray is lowered drastically in each category compared to regular hair conditioner.
Effect of rumen fungi on potential of biogas production in anaerobic digesters fed with different lignocellulosic compounds
(Thesis (M.S.) - Bogazici University. Institute of Environmental Sciences, 2016., 2016.) Yıldırım, Elif.; İnce, Bahar Kasapgil.; Aydın, Sevcan.
Although lignocellulosic biomass are considered as an alternative biogas source, they also cause rate limitation in hydrolysis step of anaerobic digestion process, negative effect on the performance of anaerobic digesters and reduction in yield. Thus, they can be also defined as a significant problem in energy production from animal manure, microalgae and macroalgae. Anaerobic rumen fungi can be seen as a potential treatment method to improve the biogas production because they produce pretty much hydrolyze enzymes. In this study, effects of anaerobic rumen fungi on the performance of anaerobic digesters and biogas production from different lignocelluloosic compounds and also microbial community dynamics during anaerobic digestion process were investigated. In the different three sets, it was examined that effects of bioaugmentation with anaerobic rumen fungi at various ratios of inoculums on biogas production of anaerobic digesters fed with animal manure, microalgae and macroalgae respectively. The highest biogas productions reached 5500 ml in digester R2, 6250 ml in digester F5 and 3500 ml in digester A1. It was also found that the highest methane productions are 60% for animal manure, 57% for microalgae H. pluvialis and 54,7% for macroalgae Ulva lactuca due to addition of anaerobic rumen fungi. Changes in quantity and diversity of bacterial and archaeal communities were detected by lllumina MiSeq sequencing technology. Changes in the number of total cells of fungi were analysed by qPCR to show effect of anaerobic rumen fungi on biogas production from different lignocellulosic compounds.
Water quality assessment of an indoor swimming pool
(Thesis (M.S.) - Bogazici University. Institute of Environmental Sciences, 2016., 2016.) Uzun, Şule.; Bekbölet, Miray.
This study investigated the quality of Boğaziçi University indoor swimming pool water by using physical, chemical and microbiological parameters. Physical parameters were temperature, color, turbidity, conductivity, salinity and TDS. Chemical parameters were pH, alkalinity, hardness, free chlorine, ammonia, TKN, oxidizability, common anions, metals, and organic carbon. Moreover, UV-vis absorption and fluorescence spectra of samples were recorded. Microbiological parameters were heterotrophic plate count, total coliforms, fecal coliforms, fecal streptococci, Pseudomonas aeruginosa and Escherichia coli. Hygienic habits and behaviors of pool users were evaluated by questionnaires. The results of physical and chemical parameters and heterotrophic plate count conformed to those recommended by authorities. Escherichia coli, total coliforms and fecal coliforms were not identified. 35 strains were identified: Pseudomonas spp. were the most frequently isolated bacteria (34%); 20% of the identified strains were Pseudomonas aeruginosa; the rest were various bacteria. This study has revealed that waters of indoor swimming pools in Turkey have not been examined in this context. The results indicate that pool waters should be continually monitored and Enterococci should be used as a parameter. Surveys in heavily used pools will be beneficial in revealing the hygienic habits and behaviors of pool users and directing future research on pool water quality.
The prevalence of avian malaria in the migratory birds of Aras - Iğdır region
(Thesis (M.S.) - Bogazici University. Institute of Environmental Sciences, 2016., 2016.) Dikmen, Meltem.; Bilgin, Raşit.
Avian malaria parasites spread throughout the world and affect a vast range of bird species. Plasmodium and Haemoproteus that cause avian malaria are popular models to study the ecology and evolution of parasite-host-vector interactions in the world. The studies on avian malaria have focused mostly on the avians host and the malaria parasites. Avian malaria is also a common infection amongst endemic and migratory birds. Malaria infection might cause rapid population declines or species extinctions as a result of the environmental changes and man-made activities. Trying to understand certain aspects of avian malaria such as the extent of parasite diversity, distribution and prevalence in host populations in Aras-Iğdır region, a migratory hotspot in eastern Turkey, comprise the main objectives of this thesis. For these purposes, the prevalence of Plasmodium and Haemoprateus were confirmed through PCR-based testing. We screened a total of 401 blood samples belonging to 58 bird species of 25 different families. 15 samples were identified as positive and 13 clean chromatograms of a 215 bp cytochrome b fragment of Plasmodium and Haemoprateus sequences were analyzed together with sequences from the MalAvi database. 13 lineages of Plasmodium and Haemoprateus from seven bird genera corresponded to nine haplotypes, all of which were previously not recorded. Except one Plasmodium sample, all samples clustered into the Haemoproteus clade, showing the higher prevelance of the latter in the samples from Aras-Iğdır region. The study results also showed that age-related patterns in avian malaria infections were consistent with the previous studies, where disease survival rates were highers for juveniles, when compared to adults. As a final analysis, we investigated the correlations between infections and three life history characteristics; migratory status, age, and body. The results suggest that age was a significant predictor of overall parasite presence.
Life cycle asseement of different types of cement concrete and their impacts on leed certificated buildings
(Thesis (M.S.) - Bogazici University. Institute of Environmental Sciences, 2016., 2016.) Hacıyusufoğlu, Begüm.; Cılız, Nilgün.
The ecosystems and biospheres of our planet are being destroyed due to the fossil fuel driven industrial development and excess production of goods. Fossil fuel combustion, land use change and overexploitation of resources have raised the global mean surface temperature. Concrete production is a highly resource and emissions intensive process due to its cement content. Considering the carbon dioxide (CO2) emissions associated with the calcination process and the combustion of fuels during clinker production, and the abiotic resource depletion of fossils and elements, a more eco-designed concrete should involve environment friendly clinker substitutes and supplementary cementitious materials (SCMs) in cement and in concrete as well as refuse derived fuels in fuel mix to create significant reduction in resource and emissions intensity. Moreover, the construction industry generates significant amount of waste that should be managed and integrated to value chain in the view of circular economy. In this study, an integrated approach of application of waste to energy targets, utilizing clinker substitutes, SCMs and construction and demolition waste (CDW) in concrete mix will be interpreted with Life Cycle Assessment (LCA) for different selected scenarios. The results represent the environmental savings through the integrated approach in terms of their relatively reduced contribution to global warming, acidification, eutrophication, photochemical ozone creation, human toxicity and abiotic resource depletion of fossils and elements. In addition, the eco-designed concrete to be defined as a result of LCA study will be evaluated in terms of LEED green building certification system.
Effect of disintegration methods on the characteristics of biological sludges and the biogas production in anaerobic digestion
(Thesis (M.S.) - Bogazici University. Institute of Environmental Sciences, 2016., 2016.) Karataş Yavuz, Özlem.; Erdinçler, Ayşen.
Pretreatment has become popular to enhance digestibility and minimization of the sludge by increasing its solubility. This study investigated the effects of ultrasonic, microwave and alkaline pretreatments on the efficiencies of aerobic and anaerobic sludge digestion processes. The digestion efficiency was measured in terms of sludge minimization, pathogen reduction and biogas production. In the first part of the study, application conditions of pretreatment techniques were determined. In the second part, unpretreated (control) and pretreated sludge samples were digested aerobically at room temperature and anaerobically at 37oC for 30 d. Sludge pretreatments improved the efficiencies of both aerobic and anaerobic digestion processes by increasing the solubility of sludge solids. In aerobic digestion, VS removal efficiencies improved by 23-68%, 24-33%, 28-78% for sludge pretreatment ratios (SPR) of 10%, 20%, and 25%, respectively. In anaerobic digestion, pretreatments led to 18-53% increase in VS removal efficiency and 41-77% increase in methane production efficiency. The highest biogas yield of 0.52 Lbiogas/gVSadded and methane yield of 0.37 LCH4/gVSadded were obtained from microwave pretreated sludge samples. Sludge dewaterability was deteriorated with the application of pretreatments to 10% of the samples (SPR:10%), dewaterability of alkaline and microwave pretreated sludge samples improved when SPR increased to 20% and 25%.
Temporal coastal erosion changes analysis using remote sensing in northern Terkos lake
(Thesis (M.S.) - Bogazici University. Institute of Environmental Sciences, 2016., 2016.) Kaya, İsmail.; Yenigün, Orhan.; Mater, Barış.
Istanbul`s drinkable / useable water demand is provided by its nearby surface water resources (Yüzeysel Su Kaynakları Raporu, İMP 2005). The cities` exponentially increasing water need can not be satisfied with the existent water resources and new solutions should be provided to tackle the upcoming water shortness problem in the following decades. Terkos Lake is one of the most crucial surface water resources of Istanbul city. Inevitably, as a result of increasing population, irregular urbanization over the Istanbul in the last 20 decades, qualities of the water basins have been reduced dramatically. All precautions taken and aggressive rules and regulations imposed did not prevent the water basins enough from environmental pollution (Çodur, 2004). Remote sensing is a principle investigation method for large scale geographic locations. This method has been used for a lot research area (Gedik, 2006) like agricultural and geological branches. It is also a handy tool in environmental risk assessments. This study will initially focus on the satellite images which were converted into image vectors with the use of ArcMap and finally assess the status of Terkos Lake with the vector- time analysis.
Antibiotic resistant pseudomonas SP. biomigi protects susceptible bacteria from disinfectants
(Thesis (M.S.) - Bogazici University. Institute of Environmental Sciences, 2016., 2016.) Gül, Gökçin.; Tezel, Ulaş.
Benzalkonium chlorides (BACs), are one of the biocides that are active ingredients of many disinfectants. A novel bacteria Pseudomonas sp. BIOMIG1 which is resistant to BACs and degrade BACs at high concentrations has recently been isolated. The objective of this research is to evaluate antibiotic resistance of BIOMIG1 and elucidate the impact of BIOMIG1 on the efficacy of BAC containing disinfectants. Tolerance of BIOMIG1s, E. coli and Serratia marcescens against 18 antibiotics was measured by using macro dilution and E-test methods. BAC resistant bacteria were more resistant to tested antibiotics than BAC susceptible bacteria which suggested that BAC resistance favor antibiotic resistance. Antibiotic biodegradation potential was tested in shake-flasks. While BIOMIG1 did not biodegrade antibiotics, Serratia marcescens degraded amoxicillin and penicillin g. Lastly, BAC susceptibility of E.coli, in the presence of BIOMIG1 in co-culture was investigated. Domestos® was used as BAC source. Experiments were performed in liquid medium. While E. coli alone was survived up to 4 mg/L initial BAC, it survived at up to 125 mg/L initial BAC in co-culture which suggested that BIOMIG1 protect E. coli from disinfectant.
Investigation of nitrification characteristics of a nitrogenous industrial wastewater
(Thesis (M.S.) - Bogazici University. Institute of Environmental Sciences, 1994., 1994.) Gökçin, Pınar.; Çeçen, Ferhan.
Treatment of wastewaters containing very high amounts of nitrogen is a problem for industries like the fertilizer industry. Up to date methods like air stripping or ion exchange can also be used in removal of nitrogen but they have certain disadvantages. The main purpose of this thesis was to present another known process used in nitrogen removal. The general concern of the study is to determine if nitrification process could tolerate industrial wastewaters containing high concentrations of nitrogen. In the beginning of the experimental part of the study, sludge previously acclimated to nitrification was introduced to increasing concentrations of ammonium nitrogen. In the second part of the study, wastewater from a fertilizer industry was used in order to detect the removal capacity of the system. Throughout the study effects of pH on the system and the system's tolerance was observed. Data obtained during the study proved that nitrification is a process that behaves according to the zero order kinetics. Finally, the results indicated that a nitrification process can surmount very high amounts of nitrogen if the environmental conditions are idealized.
Evaluation of recovery potential for precious and rare earth metals from e-waste
(Thesis (M.S.) - Bogazici University. Institute of Environmental Sciences, 2016., 2016.) Şahan, Merve.; Demirel, Burak.
Considering the enormous production of electrical and electronic wastes in recent years, it is obvious that the research of their material composition is essential in order to manage them properly and prevent health and environmental problems resulting from their inappropriate disposal. On the other hand, it is known that the e-wastes contain valuable metals in them and these valuable metals are lost during the current disposal and recycling processes. Therefore, the detection and quantification of these metals in e-waste samples is important for increasing recycling rate of them. The main objective of this study was to evaluate the recovery potentials of certain precious and rare earth metals from e-waste. The metal characterization of twenty five different e-waste samples collected from various sources was completed as a first step. Selected base, precious and rare earth metals in these e-waste samples were detected and quantified by using ICP-OES. Since the number of printed circuit boards of mobile phone samples and motherboards of computer samples is relatively higher than the number of other samples, their recovery potentials in terms of base, precious and rare earth metals were finally determined. Results of this study show that, while the recovery of precious metals should be the main goal of the recycling process of printed circuit boards from mobile phones, the recovery of both precious metals and rare earth elements should also be the focus of the recycling process of motherboards of computers.
Fate of micropollutants during the advanced treatment of sewage sludge: degradation of triclosan, ciprofloxacin, and oxytetracycline
(Thesis (M.S.) - Bogazici University. Institute of Environmental Sciences, 2015., 2015.) Mercan, Nazire.; Balcıoğlu, Işıl.
Antimicrobials are emerging organic contaminants that enter wastewater network as consequence of human activities. In contrast to other emerging organic contaminants, antimicrobials have the potential to cause a secondary pollution. In order to eliminate the environmental risk of both antimicrobial and antimicrobial resistance bacteria pollution the treatment of these contaminants in sewage sludge could be necessary. Considering these facts, the fate of a model antimicrobial Triclosan (TCS) in waste secondary sewage sludge was investigated during the application of heat and ferrous iron activated persulfate process. An experimental design methodology was applied for this thermochemical process to evaluate the combined effects of selected parameters. The degradation rate of TCS was >99.9% with 22.7 mM dose of persulfate and 0.5 molar ratios of Fe2+/S2O8 2– at 75 °C in 90 min treatment period. While increasing dose of persulfate and temperature have positive influence on TCS degradation higher dose of Fe2+ reduced the treatment efficiency of the process. However, the addition of iron to persulfate process shortened the treatment period required for effective antimicrobial degradation, enhanced the solubilisation of sludge constituents, and caused a reduction in Adsorbable orgnic halogens (AOX) values of sludge by providing both sulphate and hydroxyl radicals in the sludge. The beneficial effects of iron addition in persulfate process were not limited with these it also provided the recovery of phosphorous in the solid phase of the sludge and slight improvement in sludge dewaterability. Activation of persulfate with microwave (MW) irradiation resulted in lower extractable protein in the sludge than that obtained by Heat/Fe2+/S2O8 2- treatment.
Activated carbon production from pretreated and fermented agricultural residues
(Thesis (M.S.) - Bogazici University. Institute of Environmental Sciences, 2016., 2016.) Yıldırım, Hacer.; Cılız, Nilgün.
All forms of lignocellulosic biomass consist of three major chemical components: cellulose, hemicellulose and lignin. The remaining lignin from bioethanol production can be utilized as a feedstock for green chemicals. The purpose of this study was to produce activated carbon from pretreated and fermented agricultural residues and to investigate the influence of different process conditions such as feedstock type, impregnation ratio, and carbonization temperature on the pore structure of the products. This is the first study that investigated the production of activated carbon as a high value-added product from lignin-rich residues generated from bioethanol processes. The first step in the experimental path of the study was the recovery of lignin-rich biomass samples. Four samples were prepared from ethanol production wastes; the first one was from the pretreatment of corn stover, the second one was from pretreatment of wheat straw, the third one was from fermentation of corn stover, and the fourth one was from fermentation of wheat straw. The second step was the chemical characterization of feedstocks. In the third step, feedstocks were impregnated with 30%, 40% and 50% (w/w) H3PO4 and then carbonized with a rate of 20ºC/min to carbonization temperatures of 400ºC, 500ºC, 600ºC and 700ºC. The N2 adsorption/desorption capacities of products were compared according to their specific surface area and pore volume by applying the Brunauer-Emmett-Teller (BET) equation. The results demonstrated that the best way to produce activated carbon from lignin-rich residue was using pretreated wheat-based lignin, which was impregnated with 40% H3PO4 concentration and carbonized at 700ºC. In addition, both pretreated corn and fermented wheat-based products, which were impregnated with 50% H3PO4 and carbonized at 500ºC, had quite well developed specific surface area. Interestingly, mesoporous structures dominate in H3PO4-impregnated lignocellulosic material-based activated carbon. Therefore, these carbons are ideal for the adsorption of large molecules and decolorization.

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