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Öğe A dual approach using response surface methodology and machine learning for optimization and enhancement of microalgae-based municipal wastewater treatment(Wiley, 2025) Kayan, İremsu; Ayman Öz, NilgünBACKGROUND Municipal wastewater comprises both organic and inorganic contaminants. Especially in rural areas, conventional municipal treatment plants primarily focus on carbon removal; therefore, nutrient removal should be prioritized for preventing environmental pollution. Mixotrophic microalgae such as Nannochloropsis sp. have significant potential for both carbon and nutrient removal. However, microalgae-based wastewater systems can be affected by many parameters and, using response surface methodology and decision tree, a machine learning model can help to determine the optimal conditions for the systems to operate more efficiently. RESULTS The optimal removal conditions were determined by response surface methodology to be a light period of 21 h at an intensity of 8000 lx and a temperature value of 30 °C. Under these optimal conditions, the respective removal efficiency for chemical oxygen demand, total organic carbon, total Kjeldahl nitrogen, and orthophosphate was 53%, 34%, 87%, and 70%, respectively. Chlorophyll-a concentration increased by as much as 49%. Real municipal wastewater was used instead of synthetic wastewater, yielding closer approximations to real situations. CONCLUSION The present study has underscored innovative, data-driven approaches as core in ensuring sustainable wastewater management and sets a useful framework for future research, which could be done with the aim of refining the methods to enhance efficiency in treatment. © 2025 The Author(s). Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI).Öğe Comparison of treatability of four different chlorophenol-containing wastewater by pyrite-Fenton process combined with aerobic biodegradation: Role of sludge acclimation(Academic Press, 2021) Kayan, İremsu; Ayman Öz, Nilgün; Kantar, ÇetinAerobic biodegradation combined with pyrite-Fenton process was used for the treatment of wastewater containing different chlorophenols (4-CP, 2,3-DCP, 2,4-DCP, 2,4,6-TCP). Fenton degradation using pyrite as the low cost iron catalyst was used as a pre-treatment step to lower the toxicity of CPs prior to aerobic biodegradation. Synthetic wastewater spiked directly with either 100 mg/L CPs or pyrite-Fenton pre-treated CPs was fed to the batch bioreactors inoculated with unacclimated or acclimated activated sludge using glucose as the C-source. The results show that the CP biodegradation under aerobic conditions was highly dependent on the type of CP treated. Except for 2,4-DCP, all other CPs investigated caused severe sludge toxicity, and thus significantly hindered glucose degradation by unacclimated sludge. The CP toxicity decreased in the order of: 2,4,6-TCP > 2,3-DCP > 4-CP > 2,4-DCP. The toxic effect was explained through an interaction of CPs with the lipid fraction of cell membrane. While the pyrite-Fenton pre-treatment improved the COD removal efficiency using unacclimated sludge, the sCOD removal efficiency was still less than the control reactor operated with no CP addition. With sludge acclimation, however, the sCOD removal efficiencies increased, and approached 74% for 2,4-DCP, 61% for 4-CP, 56% for 2,4,6-TCP and 46% for 2,3-DCP, suggesting an enhanced biomass tolerance to CP toxicity. On the other hand, the sludge acclimation combined with pyrite Fenton pre-treatment provided the best bioreactor performance for all CPs with the sCOD removal efficiencies reaching 81% for 2,4,6-TCP, 78% for 2,4-DCP, 73% for 4-CP and 62% for 2,3-DCP. This suggests that the dechlorination of CPs with Fenton process, in conjunction with sludge acclimation, not only reduced the sludge toxicity, but also enhanced the bioavailability of CP-containing wastewater for microorganisms, especially for highly chlorinated toxic CPs such as 2,4,6-TCP. Overall, the findings highlight the need for sludge acclimation for effective treatment of chlorophenol-containing wastewater by a combined pyrite-Fenton and aerobic biodegradation system.Öğe Integrated biorefinery approach for wastewater treatment and resource recovery using mixotrophic microalgae(Çanakkale Onsekiz Mart Üniversitesi, 2025) Kayan, İremsu; Ayman Öz, NilgünTezde, miksotrofik bir deniz mikroalgi olan Nannochloropsis sp.'in hem evsel nitelikli atıksu hem de bir gıda endüstrisi atıksuyu olan peynir altı atıksuyunu (PAS) arıtma potansiyeli test edilmiştir. Ayrıca arıtım deneylerine ek olarak PAS ile kültive edilmiş mikroalg reaktörlerinden elde edilen biyokütlenin enerji ve sağlık uygulamalarında kullanım potansiyeli değerlendirilmiştir. Evsel atıksu ile kurulan kesikli reaktörlerde optimum koşullarda kimyasal oksijen ihtiyacı (KOİ) giderim verimi %53, toplam kjeldahl azotu (TKA) giderim verimi %87 ve ortofosfor giderim verimi %70 olarak elde edilmiştir. Seyreltilmiş PAS için ise optimum koşullar altında çalışan reaktörde yaklaşık %90 KOİ, %67 TKA ve %65 ortofosfor giderimi sağlanmıştır. Arıtma çalışmalarında deneysel koşulların ve mikroalg atıksu oranlarının belirlenmesinde Yanıt Yüzey Yöntemi, sonuçların doğruluğunun test edilmesinde ise karar ağacı kullanılmıştır. Anaerobik kesikli reaktörlerde sığır gübresine ek substrat olarak belirli oranlarda PAS ile kültive edilmiş mikroalg biyokütlesinin biyogaz oluşumuna etkisi incelenmiştir. %20 oranında mikroalg (PAS ile kültive edilen) içeren anaerobik reaktörde en yüksek biyogaz üretimi elde edilmiştir. Bu reaktöre paralel aynı oranda sadece PAS ve sadece mikroalg reaktörleri kontrol reaktörleri olarak işletilmiştir. Ayrıca tezde PAS ile kültive edilmiş mikroalg biyokütlesinin, saf mikroalg biyokütlesinin ve bu iki farklı biyokütle ile sentezlenen gümüş nanopartiküllerin antimikrobiyal, antioksidan ve DNA kırma potansiyelleri incelenmiştir. Sürdürülebilir Kalkınma Amaçları doğrultusunda döngüsel ekonomi prensiplerine uygun olarak mikroalg-bazlı atıksuların arıtımı ve oluşan biyokütlenin çeşitli uygulamalarda kullanılabilme potansiyeli ortaya konmuştur.Öğe Integrating response surface methodology and decision tree algorithms for valorization of cheese whey wastewater(Elsevier Science Inc, 2025) Kayan, İremsu; Ayman Öz, NilgünRecently, the potential of microalgae in wastewater treatment has attracted attention. The goal of this study is to find optimum conditions for microalgae growth and the concentration of cheese whey wastewater (CWW) to get the best treatment efficiency by using response surface methodology (RSM) and the decision tree algorithm for different pollutant parameters. The study used reactors with different amounts of CWW and Nannochloropsis sp. to find the best concentrations for each parameter. The best concentration of CWW was found to be 8000 mgCOD/L, and the best concentration of Nannochloropsis sp. microalgae was found to be 2200 mgVS/L. It was found that Chemical Oxygen Demand (COD), Total Organic Carbon (TOC), Total Kjeldahl Nitrogen (TKN), and Orthophosphorus (Ortho-P) could be removed at different ranges, 77-96 %, 95-98 %, 51-97 %, and 60-99 % of CWW, respectively, depending on the different combinations of microalgae and CWW concentrations. The desirability values in RSM for COD, TOC, TKN, and Ortho-P parameters to be 0.99, 0.94, 0.78, and 0.63, respectively. The study suggests the marine microalgae (Nannochloropsis sp.) could be an alternative way to treat saline CWW, to create a circular economy. The machine learning (ML) method validates that RSM predictions are consistent and accurate. The results show that it is possible to combine traditional optimization methods with more advanced ML methods to facilitate the design and the operation of the treatment plants.Öğe The Role of Microalgae in Enhancing Anaerobic Digestion: A Bibliometric Review(Istanbul Univ Press, Fac Aquatic Sciences, 2025) Kayan, İremsu; Ayman Öz, NilgünAnaerobic digestion (AD) is a well-established and extensively explored technology for waste management. However, the literature review related to the effect of microalgae on biogas production in the anaerobic co-digestion with different substrates is limited. Using scientometric tools can offer valuable insights into research gaps and emerging trends, facilitate the updating of scientific datasets, and expand knowledge in this field. Therefore, this bibliometric review will focus on the investigation of the advancements, trends, and recent updates in the co-digestion of microalgae with different substrates. The Web of Science database was used for document selection, and the bibliometric analysis was conducted using the VOSviewer version 1.6.19 software. The findings of this study reveal that, up until 2024, the major focus areas in the field are environmental studies related to biogas production, emphasizing microbiological and engineering aspects. Key opportunities and trends identified include the integration of feedstock pretreatment before AD to enhance biogas yield and quality. Adding microalgae as a co-substrate in anaerobic reactors has emerged as a promising strategy to boost AD process efficiency. Microalgae contribute additional organic matter and nutrients for AD and provide environmental benefits such as carbon sequestration and wastewater treatment, aligning with Sustainable Development Goals (SDGs). Gaining a deeper understanding of the role of microalgae in the systems is essential to establishing AD as a profitable and sustainable waste management solution, offering substantial economic and environmental advantages.
