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Öğe Effect of nitrogen loading on denitrification, denitritation and filtration performances of membrane bioreactors fed with biogenic and chemical elemental sulfur(Elsevier B.V., 2021) Uçar, DenizAutotrophic denitrification with elemental sulfur (S0) as an electron donor is a clean and cost-effective solution for nitrogen removal from contaminated waters poor in organics and has gained increasing interest in the last decades. In contrast, less attention has been driven towards autotrophic denitritation and the effect of nitrogen oxide (N-NOx−) loading and feeding strategy on the process. This study investigates the denitrification and denitritation performances of two membrane bioreactors fed with chemically synthesized S0 (S0chem) and biogenic S0 (S0bio) under different N-NOx− loading rates (50 and 100 mg N-NOx− L−1 d−1) and feeding strategies (nitrate or nitrite only and both nitrate and nitrite) and their influence on the specific nitrogen uptake rate (SNUR) of S0-oxidizing denitrifiers. N-NOx− removal was faster with S0bio compared to S0chem at all tested N-NOx− loading rates and feeding strategies, confirming S0bio as an advantageous electron donor for autotrophic NO3− and NO2− reductions. Influent NO2− levels as high as 100 mg N-NO2− L−1 did not inhibit autotrophic denitrification and denitritation. On the contrary, batch activity tests showed that NO2− feeding resulted in higher SNUR values compared to feeding with both NO3− and NO2− and with NO3− only, confirming NO2− as a more thermodynamically favorable electron acceptor than NO3−. The impact of different operational conditions on membrane filtration performance was also evaluated, showing that S0bio was the main responsible for pressure increase and membrane fouling during bioreactor operation.Öğe Kükürt bazlı ototrofik ve metanol bazlı heterotrofik denitrifikasyon süreçlerinin çevresel etkileri(Pamukkale Üniversitesi, 2022) Yakamercan, Elif; Uçar, DenizDenitrifikasyonda inorganik elektron vericilerinin kullanılması, organik elektron vericilerine göre düşük maliyetli ve daha az atık organik kirlenme riski gibi avantajları nedeniyle popülerlik kazanmaktadır. Kükürt, ototrofik denitrifikasyonda yaygın olarak kullanılmaktadır, ancak asit ve sülfat üretimi, ana dezavantajlarıdır. Gerekli alkaliniteyi sağlamak için kireçtaşı veya çözünmüş alkalinite kaynakları kullanılır. Bu çalışmada, çevresel etkilerini (abiyotik tükenme, küresel ısınma potansiyeli, ozon tabakasının incelmesi, insan toksisitesi, tatlı su sucul ekotoksisitesi, deniz suyu ekotoksisitesi, karasal ekotoksisite, fotokimyasal oksidasyon (POCP), asitleşme ve ötrofikasyon) belirlemek için üç denitrifikasyon işleminin (kireçtaşı destekli S0 bazlı, bikarbonat bazlı S0 bazlı ve metanol bazlı denitrifikasyon) yaşam döngüsü değerlendirmesi (YDD) yapılmıştır. Bu çalışmada YDD için, SimaPro 9.1.1 yazılımının CML 1A baseline, su ayak izi için ise AWARE V1.03 metodu kullanılmıştır. Her üç grupta da başarıyla 25 mg NO3 - -N/L giderimi sağlanmış, ancak S0 bazlı denitrifikasyonda alkalinite kaynağı olarak NaHCO3'ün kullanılması durumunda çevresel etkinin diğer proseslere göre daha yüksek olduğu belirlenmiştir. YDD ‘ye göre çevresel etkinin en düşük olduğu durum kükürtün elektron kaynağı olarak ve kireçtaşının alkalinite kaynağı olarak kullanılmasında gerçekleşmiştir. En yüksek çevresel etki elektrik kullanımı kaynaklı olup, bikarbonat beslemeli grupta toplam 75.38 kg CO2 eşdeğerindeki küresel ısınma potansiyelinin 65 kg’lık kısmı elektrik kullanımından kaynaklanmaktadır. Hetetrofik denitrifikasyonda 1 kg NO3 - -N/m3 fonksiyonel birim için su ayak izi 24.3 m3 iken kireçtaşı ve bikarbonat bazlı ototorofiklerde sırasıyla 30.7 m3 ve 45.1 m3 tir. Çalışma, ototrofik denitrifikasyonun maliyet ve su kalitesi açısından heterotrofik denitrifikasyona göre avantajları olmasına rağmen, alkalinite kaynağı olarak NaHCO3 kullanımından kaçınılması gerektiğini göstermektedir.Öğe Novel gas measurement based on pressure triggered release cycles for biochemical methane potential tests(De Gruyter Open Ltd, 2021) Bekmezci, Ozan K.; Sapci-Ayas, Zehra; Uçar, DenizThis study aims to present a novel gas counter and to demonstrate its suitability for biochemical methane potential tests. In this system, the gas to be measured is collected in a chamber enclosed with two one-way solenoid valves and the absolute pressure is continuously monitored. After a trigger pressure is reached, a portion of the gas is released and the amount of the released gas is calculated according to ideal gas law and recorded. Three iterations of the supervisory control and data acquisition unit were constructed and tested for BMP measurement. Although it can be further improved and variations are possible, the presented final version works with eight reactors simultaneously and the recommended maximum gas flow is 1.24 mL/min. For those reactors, the measured/ theoretical BMP ratio was 65.3% with 4.2% standard uncertainty, which is subjectively acceptable. Therefore, it can be concluded that the concept is valid and applicable to BMP tests.Öğe Reduction of nitrate by biogenic sulfide in denitrifying membrane-sulfidogenic up flow column reactor system(2025) Yücel, Amine; Yılmaz, Tülay; Uçar, DenizSulfur- or thiosulfate- based autotrophic denitrification presents an effective and economical solution for nitrate removal from wastewater or groundwater with low concentrations of organic matter. However, the substantial production of sulfate can limit its wider application, particularly in groundwater that already exhibits high sulfate concentrations. This study evaluated the performance of a sequential system engineered for the effective removal of both nitrate and sulfate from groundwater. The system integrates autotrophic denitrification, which occurs within a membrane bioreactor (MBR), with ethanol-based sulfate reduction. A key design feature of this system is the utilization of sulfide, generated in a sulfidogenic column bioreactor, as the primary electron source for the denitrification process. The system was operated using synthetic groundwater containing nitrate at concentrations of 25 and 100 mg N/L in successive phases. While the system achieved near-complete nitrate removal across both influent nitrate concentrations, it demonstrated poor sulfate reduction performance. The original design intended for the sulfide produced from sulfate reduction in the column bioreactor to be used solely as an electron source for nitrate removal in the MBR. However, the observed low sulfate removal efficiency resulted in the carryover of organic matter from the sulfidogenic column bioreactor to the MBR, thereby fostering mixotrophic denitrification conditions. The study underscores that optimizing sulfur-based combined systems is crucial for achieving the simultaneous and efficient removal of both nitrate and sulfate.Öğe Removal of detergents in car wash wastewater by sub-surface flow constructed wetland(Bitlis Eren Üniversitesi, 2022) Nacar, Tuğba; Uçar, Deniz; Ayas, Zehra SapciSuspended substances in car washes can often be easily removed by physicochemical processes. The main problem is to remove dissolved substances such as detergents from the water. In this study, a biodegradable substance Sodium Lauryl Sulfate (SLS) was removed from the car wash wastewater by the use of Phragmites australis in the subsurface constructed wetland. For this study, 4 plexiglass reactors having an effective volume of 10.8 L with the dimensions of 15cm×45cm×20 cm were used. The experiments were conducted with vegetation which was called SCW and without vegetation which was named control group (CG), as two groups. A serial connection of two reactors was performed for each group. Up to 90% detergent removal was observed with the vegetation in the SCW with a loading rate of 75 L/(m2.d) The effluents quality showed that the treated water can be reused carwash or irrigation for landscaping.Öğe Sequential sulfur-based denitrification/denitritation and nanofiltration processes for drinking water treatment(Academic Press, 2021) Asik, Gulfem; Yilmaz, Tulay; Di Capua, Francesco; Uçar, Deniz; Esposito, Giovanni; Sahinkaya, ErkanEfficient and cost-effective solutions for nitrogen removal are necessary to ensure the availability of safe drinking water. This study proposes a combined treatment for nitrogen-contaminated groundwater by sequential autotrophic nitrogen removal in a sulfur-packed bed reactor (SPBR) and excess sulfate rejection via nanofiltration (NF). Autotrophic nitrogen removal in the SPBR was investigated under both denitrification and denitritation conditions under different NO3− and NO2− loading rates (LRs) and feeding strategies (NO3− only, NO2− only, or both NO3− and NO2− in the feed). Batch activity tests were carried out during SPBR operation to evaluate the effect of different feeding conditions on nitrogen removal activity by the SPBR biofilm. Bacteria responsible for nitrogen removal in the bioreactor were identified via Illumina sequencing. Dead-end filtration tests were performed with NF membranes to investigate the elimination of excess sulfate from the SPBR effluent. This study demonstrates that the combined process results in effective groundwater treatment and evidences that an adequately high nitrogen LR should be maintained to avoid the generation of excess sulfide.Öğe Tekstil Endüstrisi Atıksularının Dinamik ve Mikrofiltrasyon Membranları ile Arıtımında Filtrasyon Performans Kıyaslanması ve Kirletici Karakterizasyonu(Erciyes Üniversitesi, 2021) Yurtsever, Adem; Başaran, Erkan; Uçar, DenizMembran filtrasyonu, tekstil endüstrisi atıksularının arıtımı için kullanılan en umut verici teknolojilerden biridir. Literatürde kirlenme kontrolü üzerine oldukça fazla sayıda çalışma yapılmasına rağmen, membran kirlenmesi son derece önemli bir sorun olmaya devam etmektedir. Bu çalışma kapsamında, işletilen bir tekstil endüstrisi atıksuyu arıtımı için işletilen anaerobik dinamik membran biyoreaktör (AnDMBR)’de meydana gelen membran kirlenmesinin karakterizasyonu yapılmıştır. Ayrıca eş zamanlı olarak işletilen mikrofiltrasyon (MF) membranı ile kıyaslanması yapılmıştır. Bu amaçla çalışmada, jel permeasyon kromatografisi (GPC), taramalı elektron mikroskopisi (TEM), Fourier Dönüşümlü Kızıl Ötesi Spektrofotometre (FTIR) ve kirlenme hızı (FR) analizleri gerçekleştirilmiştir. Kek tabakası oluşumunun ardından dinamik membran ile mikrofiltrasyon membranı benzer filtrasyon verimleri göstermiştir. Karakterizasyon analizleri ise dinamik tabakada 1 kDa’dan 9000 kDa’ya kadar geniş bir aralıkta moleküler büyüklüğe sahip partiküllerin büyük oranda mikrobiyal ürünlerce oluşmuş kek tabakası sayesinde filtrelendiğine işaret etmektedir. Yapılan TEM görüntülemesinde, MF membranında dinamik membrana kıyasla daha pürüzsüz ve gözeneksiz bir yapı gözlenmiştir. Dinamik membrandaki kirlenme hızı da MF membranınkinden daha düşük olarak elde edilmiştir.Öğe The effect of reduced graphene oxide addition on methane production from municipal organic solid waste(John Wiley and Sons Ltd, 2021) Gökçek, Öznur B.; Muratçobanoğlu, Fatma; Muratçobanoğlu, Hamdi; Uçar, Deniz; Mert, Ruhullah A.BACKGROUND: Conductive materials have become the focus of recent studies to accelerate and stabilize the conversion of organic wastes to methane in anaerobic digestion processes. In this study, the effect of the addition of reduced graphene oxide (rGO) on biogas/biomethane production from municipal organic solid wastes in anaerobic batch reactors was investigated. In this context, the effect of loading ratios (0, 0.5, 1 and 2 gVS inoculum (gVS nutrient)−1) and rGO addition at different concentrations (0, 10, 20 and 30 mg L−1) was examined during a 45-day study period. RESULTS: The highest biogas production reached a level of 816 ± 14 mL (gVS)−1 when substrate/inoculum ratio was 1 and 20 mg L−1 rGO was added (50% more than the group without rGO added). Addition of 30 mg L−1 rGO resulted in 667 ± 12 mL (gVS)−1 corresponding to 23% higher biogas production compared to the control reactor without rGO. The highest cumulative biomethane production was observed to be 525 ± 20 mL (gVS)−1 in the reactor with 20 mg L−1 rGO added in which substrate/inoculum ratio was 1. In the reactors with 10 and 30 mg L−1 and without rGO addition biomethane productions were 448 ± 21, 401 ± 13 and 323 ± 23 mL (gVS)−1, respectively. CONCLUSIONS: Results revealed that the addition of rGO increased biomethane production from municipal organic solid wastes. It is concluded that rGO addition has the potential to be applied for real-scale facilities within the scope of renewable energy production and circular economy. © 2021 Society of Chemical Industry.Öğe Utilization of excess microorganisms as carbon and electron sources in the sulfate reduction process(John Wiley and Sons Ltd, 2024) Yilmaz, Tülay; Uçar, DenizBACKGROUND: The cost of the substrate plays a crucial role in sulfate-containing wastewater treatment. Utilizing a natural or low-cost substrate is essential for effective sulfate reduction. This study investigates and compares the sulfate reduction performance of excess yeast and excess activated sludge as substrates to that of ethanol, one of the most commonly used substrates. RESULTS: Both waste sludge groups underwent initial anaerobic digestion and were subsequently fed into an anaerobic up-flow bed reactor. The reactor operated through five periods using synthetic water containing 2000 mg SO42? L?1. To assess electron donor performance during transitions between carbon sources, famine periods (without substrate addition) were implemented. Maximum sulfate reduction efficiencies for ethanol, excess yeast and excess activated sludge, and yeast were 89%, 54% and 70%, respectively, with corresponding chemical oxygen demand oxidation rates of 86%, 81% and 92%. The ethanol-fed period exhibited the highest sulfide (720 mg L?1 on day 116) and alkalinity (2035 mg CaCO3 L?1 on day 109) production. It is evident that waste activated sludge, primarily composed of prokaryotic bacteria, was more susceptible to biodegradation than eukaryotic waste yeast. CONCLUSIONS: While ethanol is a favorable source of electrons, this study suggests that the waste products of biological processes can serve as an alternative to ethanol for sulfate reduction. This approach has the potential to reduce operating costs in treatment systems by using biological waste as a carbon source. © 2023 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI). © 2023 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI).
