Environmental Engineering / Çevre Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/4321
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Article Fabrication of Superhydrophilic Teos-Lactic Acid Composite Films and Investigation of Biofouling Behaviour(Yıldız Teknik Üniversitesi, 2022) Ervan, Tuğçe; Küçüker, Mehmet Ali; Cengiz, UğurPhytoplankton and diatom microalgae species cause biofouling by adhering to the surfaces, especially in closed cultivation systems such as tubular photobioreactors. This biofilm formation blocks the sunlight; after harvesting, it is necessary to clean the reactor. This cleaning process causes loss not only for time and finance but also in terms of environmental pollution due to using toxic chemicals and excess water usage. This study aimed to investigate the reduction of the microorganism cell adhesion on the hybrid surface. To succeed in this, the composite surface of tetraethoxysilane (TEOS) and lactic acid (LA) was prepared by the sol-gel process. Then the hybrid surfaces were coated on glass slides by the dip coating method. The wettability performance of the TEOS-LA hybrid surface was investigated using contact angle measurement and light transmittance. The wettability result showed that the superhydrophilic surface having 54 mJ/m2 of surface free energy values was obtained. An increase in the lactic acid content of the composite films increased the surface free energy (SFE) values decreasing the water contact angle. A pencil hardness test characterized the mechanical strength of the surfaces, and it was determined that the hardness of the composite films was decreased by increasing the LA content of the composite films. Resultantly, it is found that the TEOS-LA superhydrophilic composite film reduces the adhesion of microalgae.Article Cyanobacterial Communities in Mucilage Collected From Çanakkale Strait (dardanelles): Metagenomic Approach(Çanakkale Onsekiz Mart Üniversitesi, 2022) Yılmaz, Sevdan; Kahraman Yılmaz, Dilek; Çelik, Ekrem Şanver; Küçüker, Mehmet AliIn this study, cyanobacterial communities in mucilage samples collected from three stations in the Dardanelles Strait were analyzed with a metagenomic approach. Mucilage samples were collected at the beginning of June 2021 from three points of the Dardanelles (Station 1: 40°6'42.78"N, 26°23'57.00"E; Station 2: 40°9'8.09"N, 26°24'16.19"E; Station 3: 40°6 '21.62"N, 26°22'41.25"E). The dominant cyanobacteria were Prochlorococcus marinus (39.17%), Synechococcus sp. (20.85%), Lyngbya sp. (12.00%), Trichodesmium erythraeum (7.33%), Aphanocapsa sp. (4.33%) and Leptolyngbya sp. (3.33%), which constituted 87.00 % of the total number of sequences. In this study, cyanobacteria species that can cause harmful algal blooms and have toxic effects on the mucilage structure have been determined. The Marmara Sea and the Dardanelles Strait, which have been affected by serious disturbances, including industrial activities, anthropogenic impacts, tourism and artificial lighting, will never be fully restored to their former ecological state. In addition, cyanobacteria species in the mucilage may cause harmful algal blooms and have toxic effects that threaten the future well-being of coastal populations and ecosystem stability. Thus, the government and local authorities should pay more attention to combating the mucilage.Review Citation - WoS: 41Citation - Scopus: 42Review on the Parameters of Recycling Ndfeb Magnets Via a Hydrogenation Process(American Chemical Society, 2023) Habibzadeh, Alireza; Küçüker, Mehmet Ali; Gökelma, MertolRegarding the restrictions recently imposed by China on the export of rare-earth elements (REEs), the world may face a serious challenge in supplying some REEs such as neodymium and dysprosium soon. Recycling secondary sources is strongly recommended to mitigate the supply risk of REEs. Hydrogen processing of magnetic scrap (HPMS) as one of the best approaches for magnet-to-magnet recycling is thoroughly reviewed in this study in terms of parameters and properties. The processes of hydrogen decrepitation (HD) and hydrogenation-disproportio-nation-desorption-recombination (HDDR) are two common methods for HPMS. Employing a hydrogenation process can shorten the production route of new magnets from the discarded magnets compared to other recycling routes such as the hydrometallurgical route. However, determining the optimal pressure and temperature for the process is challenging due to the sensitivity to the initial chemical composition and the interaction of temperature and pressure. Pressure, temperature, initial chemical composition, gas flow rate, particle size distribution, grain size, and oxygen content are the effective parameters for the final magnetic properties. All these influencing parameters are discussed in detail in this review. The recovery rate of magnetic properties has been the concern of most research in this field and can be achieved up to 90% by employing a low hydrogenation temperature and pressure and using additives such as REE hydrides after hydrogenation and before sintering.Article Characterization of Asbestos in Ambient Air During Refractory Material Production From Magnesite Ore(Çanakkale Onsekiz Mart Üniversitesi, 2021) Küçüker, Mehmet AliAsbestos is a general term employed for crystallized silicate minerals in fibril form. It can be commonly found in nature and from which fibre uses in the industry through processing are obtained. It is dielectric and fibrous, having an elastic feature. However, there is limited information about the air quality in terms of asbestos for the companies that produce refractory materials from magnesite ore. This deficiency in the literature can be eliminated with this study for a company with high quality and durable refractory materials. Among the most commonly used asbestos analysis are scanning electron microscope (SEM), transmission electron microscope (TEM). Asbestos analyses have been performed in two different institutions on the parallel samples whose preliminary processes have been completed. According to the results of the examinations conducted by SEM, 23 of the fibrils observed in a total area are bigger than five µmin lengths and less than 3 µm in width. Three of these fibrils were observed to have the characteristics of chrysotile fibres morphemically and elementally. In addition, airborne samples were analyzed using a TEM instrument. According to the results obtained, 13 of the fibrils observed in total were bigger than 5 µm in length and less than 3 µm in width and based on ED analysis and elemental composition (EDXA) results of these fibrils, and they were not observed to have the characteristics of chrysotile fibres. The majority of the fibrils observed were noted to be other inorganic minerals (lizardite) fibrils. Additionally, the obtained results show that the asbestos concentration in the air is below the limit specified by the provision (0,1 fiber/cm3).Book Part Citation - Scopus: 3Biogas Production From Aquatic Biomass(Elsevier, 2022) Wieczorek, Nils; Kosheleva, Arina; Kuchta, Kerstin; Önen Çınar, Senem; Küçüker, Mehmet AliThe use of aquatic biomass such as algae, macrophytes, or submerged macrophytes as raw material for biogas production has numerous technical and biological advantages. In addition, synergy effects can be exploited taking into account the implementation of biogas systems in urban areas, and coupling between the production of aquatic biomass, biogas production, and urban material flows can be established. Aquatic biomass, which can be the residue of downstream processes or collected from water bodies in cities, represents an excellent opportunity for both material and energy needs. Anaerobic digestion is a widely implemented technology that is already proven for the treatment of various biomasses. Several studies showed that aquatic biomass is a valuable substrate with its high methane yield, especially codigestion processes. This chapter represents the main idea of the anaerobic digestion process while focusing on the features of the aquatic biomass applications in this process.Article Shotgun Metagenomic Analysis for Mucilage in the Surface Waters of the Çanakkale Strait (dardanelles): Metabolic Diversity, Microbial Community Structure and Antibiotic Resistance Genes(2021) Yılmaz, Sevdan; Kahraman, Dilek; Çelik, Ekrem Şanver; Küçüker, Mehmet AliIn this study, we used shotgun metagenome sequencing to examine the metabolic diversity, microbial community structure and diverse antimicrobial resistance genes of mucilage in the surface waters of the Çanakkale Strait (Dardanelles). Mucilage samples were collected in April 2021 from the three different stations of the Dardanelles. The dominant microbial communities at the phylum level were Bacteroidetes (20.06%), Proteobacteria (13.68%), Verrucomicrobia (6.25%), Planctomycetes (3.02%) and Cyanobacteria (2.5%). Metabolic pathway analysis using KEGG (Kyoto Encyclopedia of Genes and Genomes) revealed that most of the genes of mucilage samples were involved in unclassified (73.86%) followed by metabolism (14.45%), genetic information processing (4.16%), environmental information processing (2.57%), cellular processing (1.88%), human diseases (1.61%), and organismal systems (1.47%). The dfrA3 gene was the most prevalent (20.36%) followed by CRP (18.17%), PmrE (14.92%), rpoB2 (11.17%), SoxR (7.49%), AbeS (6.83%), baeR (5.22%), PmrF (3.70%), dfrA22 (2.20%), dfrA26 (1.76%), dfrA20 (1.63%), golS (1.26%), CAT (1.03%), mtrA (1.01%), TMB-1 (0.64%), novA (0.64%), dfrK (0.59%), vanXB (0.48%), dfrG (0.39%), FosC2 (0.31%), and MexA (0.20%) genes. Antibiotic resistance gene (ARG) types mainly included the resistance genes of multidrug (40.19%), trimethoprim (26.93%), polymyxin (18.62%), rifamycin (11.17%), chloramphenicol (1.03%), aminocoumarin (0.64%), beta-lactamase (0.64%), fosfomycin (0.31%), and vancomycin (0.48%). Antibiotic-resistant bacteria in mucilage can adhere to human skin during swimming, fishing, water sports etc., enter the body through the nose and mouth, and transfer genetic information to the bacteria in contact areas in the human body. Therefore, this situation is risky in public health, and necessary precautions should be taken. In the light of these findings, it has been observed that there is a need for more detailed studies in the future.Article Metagenomic Characterization of Planktonic Communities During a Mucilage Event in the Çanakkale Strait (dardanelles), Turkey(2021) Yılmaz, Sevdan; Küçüker, Mehmet Ali; Kahraman, DilekThe present study investigates the planktonic communities through metagenomics sequencing during a mucilage event in the Çanakkale Strait (Dardanelles), Turkey. Mucilage samples were collected in May 2021 during an intense period of mucilage formation in three different stations of Dardanelles (Station 1: 40°9'8.09"N, 26°24'16.19"E; Station 2: 40°6'21.62"N, 26°22'41.25"E; Station 3: 40°6'42.78"N, 26°23'57.00"E). The dominant planktonic eukaryotes, at the phylum level, were Dinoflagellata (38.57%), Protalveolata (15.03%), Diatomea (12.41%), Nematozoa (8.44%), Apicomplexa (6.79%) and Chlorophyta (5.43%), which constituted 86.68 % of the total number of sequences. The most dominant OTUs (>10%), were Alexandrium and Syndiniales Group II. other dominant OTUs (>2%) were Viscosia sp., Lankesteria, Arcocellulus, Thalassiosira and Nannochloris. This study has clarified the situation of planktonic communities during a mucilage event in the Çanakkale Strait (Dardanelles), Turkey. As a result, the most dominant genus was Alexandrium, which has been known to produce mucilage. Some Alexandrium species can produce toxins, cause severe impacts on human health, and lead to bivalve, shrimp, and fish mortality. Therefore, a more detailed study is needed to determine the Alexandrium toxins in the mucilage structure. In addition, the heavy metal content of the obtained mucilage was investigated, and the concentrations of the As and Cr are above the disposal limits in the landfill sites. Therefore, collected mucilage from the sea surface should be checked before sending it to landfill sites in terms of the heavy metal content.