Çevre Mühendisliği

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http://hdl.handle.net/11527/19644

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  • Öge
    Marmara Denizi'nde Deniz Salyası Sorunu ile İlgili Görüş ve Öneriler
    (İstanbul Teknik Üniversitesi, 2021-06-18) Öztürk, İzzet ; Yanalak, Mustafa ; Arslan, Özcan ; Koyuncu, İsmail ; Dilekgürgen, Ebru ; Erşahin, Mustafa Evren ; Türken, Türker ; https://orcid.org/0000-0002-8274-5326 ; Çevre Mühendisliği
    Müsilaj doğrudan bir kirlilik olmayıp, birçok farklı alanda zincirleme olarak olumsuzlukların tetiklenmesine neden olmaktadır (Şekil 1 ve Şekil 2). Bu olumsuzluklar arasında deniz canlılarının yok olması, balıkçılığın olumsuz etkilenmesi, deniz ve kıyı turizminin zarar görmesi, gemi ve deniz araçlarının zarar görmesi, atmosfere zararlı gazların salınması sayılabilir. Müsilaj oluştuktan sonra, çeşitli deniz vasıtaları ve sistemleri ile sınırlı şekilde denizden toplanmasından başka çözüm olmadığından, müsilajın oluşumuna neden olan faktörleri yok etmek en uygun çözüm olacaktır.
  • Öge
    Nadir Toprak Elementleri ve Atıklardan Geri Kazanımı Çalıştayı Bildiri Kitabı, İstanbul, 2021
    (İstanbul Teknik Üniversitesi, 2021-12-01) Çevre Mühendisliği ; Koyuncu, İsmail ; Köse Mutlu, Börte ; Yüksekdağ, Ayşe ; Tuncay, Gizem ; Akça, Tuğçe
    Nadir Toprak Elementleri bilgisayar, cep telefonu, floresan lambalar, bataryalar gibi elektrikli ve elektronik ürünlerden, rüzgâr türbinleri, güneş panelleri gibi yenilenebilir enerji ürünlerine kadar birçok sektörde kullanılan bir element grubudur. Nadir toprak elementlerine yönelik talep gün geçtikçe artmaktadır. Nadir toprak elementlerinin mevcut rezervlerden elde edilmesinin yanı sıra ekonomik modelin lineerden döngüsele geçmesiyle beraber nadir toprak elementlerinin sürdürülebilirlik kavramı çerçevesinde ülkemizde ve dünyada geri kazanımı için çalışmalar yapılmaktadır. İTÜ Çevre Mühendisliği Bölümü ve MEM-TEK Ulusal Membran Teknolojileri Araştırma Merkezi bünyesinde, bu elementlerin döngüsel ekonomi çerçevesinde çeşitli atık, atıksu ve ikincil kaynaklardan geri kazanımına dair yürütülen 11Y357 no’lu TÜBİTAK 1001 projesi kapsamında “Nadir Toprak Elementleri ve Atıklardan Geri Kazanımı Çalıştayı” organize edilmiştir.
  • Öge
    Assessment of Microbial Diversity during Thermophilic Anaerobic Co-Digestion for an Effective Valorization of Food Waste and Wheat Straw
    ( 2022-12-21) Yangın Gömeç, Çiğdem ; Agnihotri, Swarnima ; Ylitervo, Päivi ; Sárvári Horváth, Ilona ; 0000-0003-3519-4821 ; Environmental Engineering
    In this study, predominant bacterial and archaeal populations and their roles during anaerobic mono-digestion of food waste (FW) and co-digestion of FW with straw pellets (SP) at thermophilic temperature (53 ± 1 °C) were assessed by Next Generation Sequencing (NGS) analysis at organic loading rates (OLRs) of 3.0 and 7.0 gVS/L/d. Depending on the seed; results revealed that Firmicutes, Bacteroidetes, and Proteobacteria were, respectively the most prevalent bacterial phyla at both OLRs investigated. On the other hand, Euryarchaeota was dominated by methanogens playing crucial role in biogas production and correlated mainly with the activities of Methanobacteria and Methanomicrobia at class level. Acetoclastic Methanosaetae was the predominant genus at OLR = 3.0 gVS/L/d; however, shared the same predominance with hydrogenotrophic methanogens Methanospirillium at the highest OLR. Although no clear effect in response to straw addition at OLR of 3.0 gVS/L/d could be seen in terms of methanogenic archaea at genus level, hydrogenotrophic methanogens revealed some shift from Methanobacterium to Methanospirillium at higher OLR. Nevertheless, no prominent microbial shift in the presence of wheat straw at increased OLR was likely due to adapted inoculation at start-up which was also demonstrated by relatively stable biogas yields during co-digestion.
  • Öge
    Analysis of particle size distribution of organic carbon for landfill leachate : implications for sustainable treatment
    (Wiley, 2023) Doğruel, Serdar ; Kaya, Beste ; Soylu, Dilşad ; Çokgör, Emine ; Baran, Aydın ; Sözen, Seval ; Orhon, Derin ; orcid.org/0000-0003-4214-8436 ; orcid.org/0000-0001-6158-4132 ; orcid.org/0000-0002-5417-0318 ; orcid.org/0000-0002-4904-6056 ; orcid.org/0000-0003-2027-604X ; orcid.org/0000-0002-6823-3498 ; Çevre Mühendisliği
    BACKGROUND Landfill leachate has a complex composition requiring experimental support to formulate a sustainable treatment strategy. This study utilized the particle size distribution (PSD) of the chemical oxygen demand (COD) content to assess the profile of biodegradable and inert COD fractions; it also emphasized the functions and benefits of ultrafiltration and nanofiltration modules coupled to an activated sludge process. The evaluation profited from the field data of a landfill site in Istanbul, where the leachate was actually treated in a membrane bioreactor (MBR) plant. RESULTS COD and total nitrogen levels fluctuated between 10 100–31 200 mg L−1 and 1150–2800 mg L−1, respectively. PSD analysis for COD, conducted at two extremes, displayed similar results, where the majority of the COD was observed to accumulate at the low extremity of the particle size, 70–72% below 2 nm. Therefore, direct membrane filtration of leachate yielded low COD removals that were limited to 9% with ultrafiltration and to 31–35% with nanofiltration. COD fractionation indicated a ratio of 5% for the inert COD in leachate. The permeate COD of ultrafiltration in the existing plant was 2000 mg L−1, much higher than the inert fraction ratio, which was further reduced to 266 mg L−1 by nanofiltration. CONCLUSION PSD analysis was an integral complement of respirometry for establishing the size-biodegradation relationships of different COD fractions. It located the majority of soluble COD fractions below 0.55 nm, thus implying the necessity of a biological process. PSD also identified the generation of soluble residual metabolic products, indicating that residual COD escaping treatment would be equally significant to the removal potential of the biodegradable substrate.
  • Öge
    Specific ammonium oxidation and denitrification rates in an MBR treating real textile wastewater for simultaneous carbon and nitrogen removal
    (Wiley, 2023) Yılmaz, Tülay ; Demir, Emir Kasım ; Teksoy Başaran, Senem ; Ubay Çokgör, Emine ; Sahinkaya, Erkan ; orcid.org/0000-0003-2416-9890 ; orcid.org/0000-0002-4904-6056 ; Çevre Mühendisliği
    BACKGROUND Dissolved oxygen (DO) and aeration on/off time are the determining parameters for simultaneous carbon and nitrogen removal in biological treatment processes. The most effective way to decide the optimum operational conditions, e.g. aeration on/off time or DO concentration during the aeration period, is to determine specific nitrification/denitrification rates. For this purpose, the effects of DO (6 and 3 mg L−1) and aeration on/off time (from 2/2 to 90/360 min) on the specific ammonium oxidation and denitritation/denitrification rates in a membrane bioreactor (MBR) treating real textile wastewater were deeply investigated. RESULTS The highest specific ammonium oxidation, denitritation and denitrification rates were obtained as 5.4, 3.8, and 5.3 mg N g−1 volatile suspended solids h−1, respectively, at an aeration on/off time of 90/360 min, which corresponded to the increase in specific ammonium oxidation rates by 1.8 and 2.1 times compared to continuous aeration conditions where DO was 6 and 3 mg L−1, respectively. CONCLUSION Higher specific ammonium oxidation and denitrification rates can be achieved with the intermittent aeration compared to continuous aeration. Hence existing treatment plants can be retrofitted for higher performance with reduced energy requirements. © 2023 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI).
  • Öge
    Energy Production from Biomass Valorization
    ( 2023-05-24) Yangın Gömeç, Çiğdem ; Sárvári Horváth, Ilona ; Martin, Carlos ; 0000-0003-3519-4821 ; Environmental Engineering
  • Öge
    Water exchange in the Dardanelles : variations on synoptic to interannual time scales
    (Springer, 2024) Saçu, Şehriban ; Şen, Olgay ; Erdik, Tarkan ; Öztürk, İzzet ; Stanev, Emil V. ; 0000-0001-9404-8424 ; 0000-0003-2545-3746 ; 0000-0002-4003-5510 ; 0000-0002-8274-5326 ; 0000-0002-1110-8645 ; Çevre Mühendisliği
    The bidirectional mass exchange between the Marmara Sea and the Aegean Sea provides one part of the critical hydrodynamic links between the Black Sea and the Mediterranean Sea. In this study, we examined exchange in the Dardanelles based on a 3-D numerical model simulation covering an 11-year period under realistic atmospheric forcing. The model includes the Black Sea, the Marmara Sea, and a part of the Aegean Sea to include the remote effects of basin dynamics. The main features as one-, two-, and three-layered flow structures are successfully reproduced by the model in comparison to earlier observations. It is found that the strait is subject to submaximal exchange by only one control near the Nara Pass. According to long-term modeling results, most variability occurs on synoptic time scales, and wind stress has a dominant role in those variations. The seasonal and interannual variability of exchange flow is relatively low and displays a close relationship with freshwater input to the Black Sea.
  • Öge
    Impact of food waste addition in energy efficient municipal wastewater treatment by aerobic granular sludge process
    (Springer, 2024) Çiçekalan, Büşra ; Berenji, Nastaran Rahimzadeh ; Aras, Muhammed Furkan ; Güven, Hüseyin ; Koyuncu, İsmail ; Erşahin, Mustafa Evren ; Özgün, Hale ; 0000-0002-1806-9917 ; 0000-0001-6431-383X ; 0000-0002-0811-9001 ; 0000-0001-6754-0106 ; 0000-0001-8354-1889 ; 0000-0003-1607-0524 ; 0000-0001-8784-8351 ; Çevre Mühendisliği
    Recently, one of the main purposes of wastewater treatment plants is to achieve a neutral or positive energy balance while meeting the discharge criteria. Aerobic granular sludge (AGS) technology is a promising technology that has low energy and footprint requirements as well as high treatment performance. The effect of co-treatment of municipal wastewater and food waste (FW) on the treatment performance, granule morphology, and settling behavior of the granules was investigated in the study. A biochemical methane potential (BMP) test was also performed to assess the methane potential of mono- and co-digestion of the excess sludge from the AGS process. The addition of FW into wastewater enhanced the nutrient treatment efficiency in the AGS process. BMP of the excess sludge from the AGS process fed with the mixture of wastewater and FW (195 ± 17 mL CH4/g VS) was slightly higher than BMP of excess sludge from the AGS process fed with solely wastewater (173 ± 16 mL CH4/g VS). The highest methane yield was observed for co-digestion of excess sludge from the AGS process and FW, which was 312 ± 8 mL CH4/g VS. Integration of FW as a co-substrate in the AGS process would potentially enhance energy recovery and the quality of effluent in municipal wastewater treatment.
  • Öge
    Effect of photocatalytic pretreatment on the membrane performance in nanofiltration of textile wastewater
    (Springer, 2024) Korkut, Sevde ; Ormancı-Acar, Türkan ; Keskin, Başak ; Ağtaş, Meltem ; Karahan, Özlem ; Demir, Tuğba U. ; Ünal, Serkan ; Menceloğlu, Yusuf Z. ; Koyuncu, İsmail ; Çevre Mühendisliği
    Traditional methods like biological treatment, flocculation-coagulation, adsorption, and advanced oxidation are commonly employed for textile wastewater treatment, but their sustainability is hindered by issues such as the adverse impact of textile wastewater on microorganisms and the requirement for substantial chemical usage. In response to increasingly stringent legal discharge standards, membrane technologies are emerging as prominent alternatives for effective textile wastewater treatment. The application of photocatalysis as a pretreatment to improve effluent quality and treatment performance has shown effective results in the treatment of textile wastewater by nanofiltration (NF). However, innovative solutions are needed to improve the efficiency of UV photocatalytic reactors. Here, the TiO2/halloysite nanotube (HNT) photocatalyst was shown to completely remove dyes under UV illumination. Two wastewater samples from photocatalytic (PC) pretreatment were treated using innovative NF membranes with different contents. The study examined the impact of PC pretreatment on the flux of wastewater from a textile factory heat recovery tank, which increased from 18.32 to 27.63 L/m2.h. The membranes achieved > 98% removal in COD, while bare membrane achieved 95% removal in conductivity. The addition of s-DADPS as monomer and HNT as nanoparticles to the membranes with different compositions affected the cross-linking in the TFC layer. During the tests conducted on the water extracted from the dyeing tank, the color was completely eliminated without any loss of flux. Additionally, improvements in COD removal were observed.
  • Öge
    Enhanced energy recovery in municipal wastewater treatment plants through co-digestion by anaerobic membrane bioreactors : current status and future perspectives
    (Springer, 2024) Cengiz, Ali İzzet ; Güven, Hüseyin ; Özgün, Hale ; Erşahin, Mustafa Evren ; 0000-0002-4715-9567 ; 0000-0001-6754-0106 ; 0000-0001-8784-8351 ; 0000-0003-1607-0524 ; Çevre Mühendisliği
    Today, the transition to renewable energy from conventional energy practices is more important than ever to establish energy security and mitigate climate change. The wastewater treatment plants (WWTP) consume a remarkable amount of energy and cause significant greenhouse gas emissions. The energy balance of WWTP can be improved by implementing energy-efficient applications such as anaerobic digestion. However, most of the existing WWTPs utilize only sewage sludge in conventional anaerobic digesters (CAD) which results in low biogas generation. Generally, co-digestion is indicated as an effective solution for the low biogas generation faced in mono-digestion. Moreover, recently, anaerobic membrane bioreactors (AnMBR) have been promoted as a prominent alternative to CADs. This paper overviews the current situation of co-digestion applications by AnMBRs for municipal WWTPs. Furthermore, the environmental and economic aspects of these applications were reviewed. Lastly, challenges and future perspectives related to the co-digestion applications by AnMBR were thoroughly discussed.
  • Öge
    Improving light availability and creating high-frequency light–dark cycles in raceway ponds through vortex-induced vibrations for microalgae cultivation: a fluid dynamic study
    (Springer, 2024) Akça, Mehmet Sadık ; Kınacı, Ömer Kemal ; İnanç, Bülent ; 0000-0002-2119-5279 ; 0000-0002-2956-9562 ; 0000-0002-5995-8657 ; Çevre Mühendisliği
    Limited light availability due to insufficient vertical mixing strongly reduces the applicability of raceway ponds (RWPs). To overcome this and create light–dark (L/D) cycles for enhanced biomass production through improved vertical mixing, vortex-induced vibration (VIV) system was implemented by the authors in a previous study to an existing pilot-scale RWP. In this study, experimental characterization of fluid dynamics for VIV-implemented RWP is carried out. Particle image velocimetry (PIV) technique is applied to visualize the flow. The extents of the vertical mixing due to VIV and the characteristics of L/D cycles were examined by tracking selected particles. Pond depth was hypothetically divided into three zones, namely dark, light Iimited and light saturated for detailed analysis of cell trajectories. It has been observed that VIV cylinder oscillation can efficiently facilitate the transfer of cells from light-limited to light-saturated zones. Among the cells that were tracked, 44% initially at dark zone entered the light-limited zone and 100% of initially at light-limited zone entered the light-saturated zone. 33% of all tracked cells experienced high-frequency L/D cycles with an average frequency of 35.69 s−1 and 0.49 light fraction. The impact of VIV was not discernible in the deeper sections of the pond, due to constrained oscillation amplitudes. Our findings suggest that the approximately 20% increase in biomass production reported in our previous study can be attributed to the synergistic effects of enhanced L/D cycle frequencies and improved light availability resulting from the transfer of cells from dark to light-limited zones. To further enhance the effectiveness of VIV, design improvements were developed. It was concluded that light availability could be significantly improved with the presented method for more effective use of RWPs.
  • Öge
    Combination of ozonation with GAC, AIX and biochar post-treatment for removal of pharmaceuticals and transformation products from municipal WWTP effluent
    (Royal Society of Chemistry, 2024) Fakioglu, Malhun ; Golovko, Oksana ; Baresel, Christian ; Ahrens, Lutz ; Öztürk, İzzet ; https://orcid.org/0000-0003-1475-2249 ; https://orcid.org/0000-0002-8274-5326 ; Çevre Mühendisliği
    Pharmaceuticals have been detected in water and wastewater, resulting in increasing research attention towards the elimination of these substances from aqueous environments. Due to the limitations of conventional processes in wastewater treatment plants (WWTPs) to fully eliminate these compounds, more research is needed on complementary advanced treatment technologies. This study aims to examine the removal efficiency for 24 selected pharmaceuticals and the fate of their 7 main metabolites including several oxidation transformation products by various technique combinations applied on the effluent from a full-scale WWTP. Investigated treatment options include ozonation (O3) combined with either granular activated carbon (GAC), two different types of biochar, and anion exchange (AIX) in a continuously operated laboratory-scale system. The average removal of analyzed pharmaceuticals ranged between 8.8–97% with an O3 dose of 0.28 g O3/g DOC (dissolved organic carbon), whereas it ranged from 86–99% for higher O3 dosages (0.96 and 2.17 g O3/g DOC). Overall, the investigated metabolites of pharmaceuticals exhibited lower removal efficiency (between −33 and 99%) with ozone compared to the parent compounds at all O3-dosages. Concentrations of oxidation transformation products such as citalopram N-oxide were increased after ozone treatment, whereas it was decreased after the columns at different rates. The bromate concentrations during all three O3-dosages (0.28, 0.96 and 2.17 g O3/g DOC) were below 5 μg L−1. GAC was the best performing sorbent among all materials, where even after two weeks of continuous operation, nearly all compounds were removed below quantification levels. Although biochar 1 showed better performance (30–89%, mean = 68%) than biochar 2 (8.5–82%, mean = 38%), both sorption materials showed reduced sorption capacity over the time period of two weeks for most of the target compounds. On the other hand, AIX had lower removal rates ranging between 2–55% (mean = 20%). Regarding the combination of O3 with the individual sorbent materials, GAC was the most successful combination with O3 for the removal of pharmaceuticals (>99%) and oxidation transformation products (>60%). The combination of O3 with biochar 1 was more successful (mean = 91%) than the combination with biochar 2 (mean = 79%), where the combination of O3 with AIX showed the lowest removal rates (mean = 58%).
  • Öge
    Membran Teknolojilerinde Biyotıkanma Çalıştayı, 9 Ocak 2025, İstanbul-Türkiye : bildiriler kitabı
    (İTÜ Yayınevi, 2025) Çevre Mühendisliği ; Koyuncu, İsmail ; Yavuztürk Gül, Bahar ; Pekgenç, Enise ; Yaşar, Sümeyye