Environmental Engineering / Çevre Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/4321
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Article Citation - WoS: 13Citation - Scopus: 14Boron Removal From Geothermal Brine Using Hybrid Reverse Osmosis/Microbial Desalination Cell System(Elsevier, 2023) Jarma, Yakubu A.; Kabay, Nalan; Baba, Alper; Ökten, Hatice Eser; Gören, Ayşegül YağmurAgriculture sector leads worldwide as the most water consuming sector with water demand. Since natural water resources cannot keep up with the demand, a shift from conventional water resources to unconventional ones is needed. While geothermal water was gaining importance for its energy content, small-scale (<10 L/s) energy plants were not required to reinject their spent geothermal brine. As geothermal resources align with agricultural areas in Western Anatolia, discharge of untreated brine might have severe adverse effects on crop yields and soil quality. In this study, we investigated use of spent geothermal brine for irrigation after treatment with Reverse Osmosis/Microbial Desalination Cell (RO/MDC) hybrid process. Treatment efficiencies for B, COD, As, Li, Fe, Cr concentrations and energy production values were determined. Treated water was initially evaluated for irrigation considering three quality categories (I, II, and III) comprised of parameters such as electrical conductivity (EC), total dissolved solids (TDS), and sodium adsorption ratio (SAR), along with sodium, chloride and boron concentrations. Additionally, magnesium adsorption ratio (MAR) and permeability index (PI) were used to evaluate for irrigation suitability. Although B concentrations in MDC-treated permeate (3.29 mg/L) and concentrate (2.99 mg/L) streams were not low enough to meet Quality I criterion (<0.7 mg/L), they can be still utilized in irrigation of moderate-to-high tolerant plants. Furthermore, PI and MAR parameters pointed to suitability for irrigational use. © 2022Article Citation - WoS: 10Citation - Scopus: 12Novel Hybrid Adsorption-Electrodialysis (aded) System for Removal of Boron From Geothermal Brine(American Chemical Society, 2022) Altınbaş, Bekir Fırat; Orak, Ceren; Ökten, Hatice Eser; Yüksel, AslıA novel hybrid adsorption-electrodialysis (AdED) system to remove environmentally harmful boron from geothermal brine was designed and effective operating parameters such as pH, voltage, and flow rate were studied. A cellulose-based adsorbent was synthesized from glycidyl methacrylate (GMA) grafted cellulose and modified with a boron selective n-methyl-d-glucamine (NMDG) group and characterized with SEM-EDX, FT-IR, and TGA analyses. Batch adsorption studies revealed that cellulose-based adsorbent showed a remarkable boron removal capacity (19.29 mg/g), a wide stable operating pH range (2-10), and an adsorption process that followed the Freundlich isotherm (R2= 0.95) and pseudo-second-order kinetics (R2= 0.99). In the hybrid AdED system, the optimum operating parameters for boron removal were found to be a pH of 10, a voltage of 10 V, a flow rate of 100 mL/min, and an adsorbent dosage of 4 g/L. The presence of the adsorbent in the hybrid system increased boron removal from real geothermal brine (containing 199 ppm boron) from 7.2% to 73.3%. The results indicate that the designed AdED system performs better than bare electrodialysis for boron removal from ion-rich real geothermal brine while utilizing environmentally friendly cellulose-based adsorbent.Article Citation - WoS: 31Citation - Scopus: 35Electrochemical Degradation of Methylene Blue by a Flexible Graphite Electrode: Techno-Economic Evaluation(American Chemical Society, 2022) Gören, Ayşegül Yağmur; Recepoğlu, Yaşar Kemal; Edebali, Özge; Şahin, Çağrı; Genişoğlu, Mesut; Ökten, Hatice EserIn this study, electrochemical removal of methylene blue (MB) from water using commercially available and low-cost flexible graphite was investigated. The operating conditions such as initial dye concentration, initial solution pH, electrolyte dose, electrical potential, and operating time were investigated. The Box-Behnken experimental design (BBD) was used to optimize the system's performance with the minimum number of tests possible, as well as to examine the independent variables' impact on the removal efficiency, energy consumption, operating cost, and effluent MB concentration. The electrical potential and electrolyte dosage both improved the MB removal efficiency, since increased electrical potential facilitated production of oxidizing agents and increase in electrolyte dosage translated into an increase in electrical current transfer. As expected, MB removal efficiency increased with longer operational periods. The combined effects of operating time-electrical potential and electrical potential-electrolyte concentration improved the MB removal efficiency. The maximum removal efficiency (99.9%) and lowest operating cost (0.012 $/m3) were obtained for initial pH 4, initial MB concentration 26.5 mg/L, electrolyte concentration 0.6 g/L, electrical potential 3 V, and operating time 30 min. The reaction kinetics was maximum for pH 5, and as the pH increased the reaction rates decreased. Consequent techno-economic assessment showed that electrochemical removal of MB using low-cost and versatile flexible graphite had a competitive advantage.Article Citation - WoS: 40Citation - Scopus: 47Boron in Geothermal Energy: Sources, Environmental Impacts, and Management in Geothermal Fluid(Elsevier, 2022) Mott, A.; Baba, Alper; Hadi Mosleh, Mojgan; Ökten, Hatice Eser; Babaei, Masoud; Gören, Ayşegül Yağmur; Feng, C.; Recepoğlu, Yaşar Kemal; Uzelli, Taygun; Uytun, Hüseyin; Morata, Diego; Yüksel Özşen, AslıThe problem of hazardous chemicals in geothermal fluid is a critical environmental concern in geothermal energy developments. Boron is among the hazardous contaminants reported to be present at high concentrations in geothermal fluids in various countries. Poor management and inadequate treatment of geothermal fluids can release excessive boron to the environment that has toxic effects on plants, humans, and animals. Despite the importance of boron management in geothermal fluid, limited and fragmented resources exist that provide a comprehensive understanding of its sources, transport and fate, and the treatment strategies in geothermal energy context. This paper presents the first critical review from a systematic and comprehensive review on different aspects of boron in geothermal fluid including its generation, sources, toxicity, ranges and the management approaches and treatment technologies. Our research highlights the origin of boron in geothermal water to be mainly from historical water-rock interactions and magmatic intrusion. Excessive concentrations of boron in geothermal fluids have been reported (over 500 mg/L in some case studies). Our review indicated that possible boron contamination in geothermal sites are mostly due to flawed construction of production/re-injection wells and uncontrolled discharge of geothermal water to surface water. The dominancy of non-ionic H3BO3 species makes the selection of the suitable treatment method for geothermal waters limited. Combining boron selective resins and membrane technologies, hybrid systems have provided effluents suitable for irrigation. However, their high energy consumption and course structure of boron selective resins encourage further research to develop cost-effective and environmentally friendly alternatives.Article Citation - WoS: 13Citation - Scopus: 14Desalination and Detoxification of Textile Wastewater by Novel Photocatalytic Electrolysis Membrane Reactor for Ecosafe Hydroponic Farming(MDPI, 2022) Aydın, Muhammed Iberia; Özaktaç, Damla; Yüzer, Burak; Doğu, Mustafa; İnan, Hatice; Ökten, Hatice Eser; Coşkun, Serdar; Selçuk, HüseyinIn this study, a novel photoelectrocatalytic membrane (PECM) reactor was tested as an option for the desalination, disinfection, and detoxification of biologically treated textile wastewater (BTTWW), with the aim to reuse it in hydroponic farming. The anionic ion exchange (IEX) process was used before PECM treatment to remove toxic residual dyes. The toxicity evaluation for every effluent was carried out using the Vibrio fischeri, Microtox® test protocol. The disinfection effect of the PECM reactor was studied against E. coli. After PECM treatment, the 78.7% toxicity level of the BTTWW was reduced to 14.6%. However, photocatalytic desalination during treatment was found to be slow (2.5 mg L-1 min-1 at 1 V potential). The reactor demonstrated approximately 52% COD and 63% TOC removal efficiency. The effects of wastewater reuse on hydroponic production were comparatively investigated by following the growth of the lettuce plant. A detrimental effect was observed on the lettuce plant by the reuse of BTTWW, while no negative impact was reported using the PECM treated textile wastewater. In addition, all macro/micronutrient elements in the PECM treated textile wastewater were recovered by hydroponic farming, and the PECM treatment may be an eco-safe wastewater reuse method for crop irrigation.Article Citation - WoS: 7Citation - Scopus: 93d Electrode Use in Mdc for Enhanced Removal of Boron From Geothermal Water(Elsevier, 2022) Gören, Ayşegül Yağmur; Ökten, Hatice EserMicrobial desalination cell (MDC) is a significantly promising technology due to its simultaneous features of electricity production, wastewater treatment and desalination. In this paper, the three-dimensional (3D) sponge with activated carbon-chitosan (AC-CS) was synthesized to enhance the efficiency of the MDC system. Effects of operating parameters (boron concentration, electrode surface area, catholyte solution, and activated sludge volume) on MDC performance were also investigated. The MDC with 3D AC-CS anode provided a higher power density of 970 mW/m2, boron removal efficiency of 75.9%, and COD removal efficiency of >90% under optimized conditions. The maximum boron and COD removal efficiencies were 65.6 and 81.4% with the power density of 866.9 mW/m2 for geothermal brine. Moreover, BET analysis showed that the 3D AC-CS anode presented high surface area (230 m2/g) and pore volume (0.202 cm3/g). As an overall result, not only the production of 3D sponge anode electrodes with AC-CS composite was achieved but also desalination and power generation results that were comparable with the literature were presented.Article Citation - WoS: 33Citation - Scopus: 37Energy Production From Treatment of Industrial Wastewater and Boron Removal in Aqueous Solutions Using Microbial Desalination Cell(Elsevier, 2021) Gören, Ayşegül Yağmur; Ökten, Hatice EserAs a result of a much needed paradigm shift worldwide, treated saline water is being considered as a viable option for replacing freshwater resources in agricultural irrigation. Vastly produced geothermal brine in Turkey may pose a significant environmental risk due to its high ionic strength, specifically due to boron. Boron species, which are generally found uncharged in natural waters, are costly to remove using high-throughput membrane technologies such as reverse osmosis. Recent advances in bioelectrochemical systems (BES) has facilitated development of energetically self-sufficient wastewater treatment and desalination. In this study, removal of boron from synthetic solutions and real geothermal waters, along with simultaneous energy production, using the microbial desalination cell (MDC) were investigated. Optimization studies were conducted by varying boron concentrations (5, 10, and 20 mg L-1), air flow rates (0, 1, and 2 L min(-1)), electrode areas (18, 24, 36, and 72 cm(2)), catholyte solutions, and operating modes. Even though the highest concentration decrease was observed for 20 mg-B L-1, 5 mg-B L-1 concentration experiment gave the closest result to the 2.4 mg-B L-1 limit value asserted by WHO. Effect of electrode surface area was proven to be significant on boron removal efficiency. Employing the optimum conditions acquired with synthetic solutions, boron and COD removal efficiencies from real geothermal brine were 44.3% and 90.6%, respectively. MDC, being in its early levels of technology readiness, produced promising desalination and energy production results in removal of boron from geothermal brine.Article Citation - WoS: 23Citation - Scopus: 30Biosorption of Methylene Blue From Water by Live Lemna Minor(Elsevier, 2021) Can Terzi, Begüm; Gören, Ayşegül Yağmur; Ökten, Hatice Eser; Sofuoğlu, Sait CemilA number of green treatment technologies have been used for textile wastewater treatment, among which phytoremediation is a low cost, effective, and promising alternative - to conventional treatment techniques. The aim of this study was to investigate performance of Lemna minor (L. minor) for phytoremediation of Methylene Blue (MB). A Box-Behnken experimental design (BBD) was applied to study individual and combined effect of operating parameters on MB dye removal efficiency: MB dye concentration (x(1): 5 - 25 mgL(-1)), amount of L. minor (x(2): 1 - 5 g), and pH of the solution (x(3): 4.5 - 9.0). Response surface analysis and response model were utilized to reveal the relationship between operating parameters and MB removal efficiency. Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM) analyses of L. minor samples were used to infer on the removal mechanism. The predicted optimum values were x(1) = 15 mgL(-1), x(2) = 4.9 g, and x(3) = 6.8, for the highest removal efficiency (98%) within 24 h. FTIR and SEM analyses indicated that the dye removal mechanism was mainly biosorption. Desorption experiments revealed that L. minor released only a small fraction of the sorbed dye. Consequently, in addition to being environmental friendly and cost effective, results of this study show that L. minor can be effectively used for MB dye removal from wastewaters while adding to the pertinent but limited literature by presenting its applicability in wider operating parameter ranges, maximization of removal efficiency through experimental design, and evidence that biosorption is a plausible mechanism. (C) 2021 Elsevier B.V. All rights reserved.Article Citation - WoS: 15Citation - Scopus: 18Simultaneous Energy Production, Boron and Cod Removal Using a Novel Microbial Desalination Cell(Elsevier, 2021) Gören, Ayşegül Yağmur; Ökten, Hatice EserThis paper investigates simultaneous boron removal from aqueous solutions, organic matter removal from industrial wastewater and energy production using a Microbial Desalination Cell (MDC). Anode chamber of the conventional MDC cell was modified to include 3D cubic electrodes as a novel design. Effects of operating parameters, including electrode type (3D-electrode and 2D-electrode), anolyte solution temperature (20 °C, 40 °C, and 60 °C), and activated sludge:wastewater volumetric ratio (S:WW = 1:1, 1:2, and 1:5), on MDC performance were studied. Furthermore, real geothermal water treatment was investigated under optimum operating conditions. Boron and organic matter removal efficiencies and the produced power density results were promising for 3D-electrodes under optimum operating conditions. The maximum boron removal efficiency, COD removal efficiency, and power density were 55.5%, 91.5%, and 9.04 mW/m3 treating real geothermal water at optimum operating conditions. The analyses of Scanning Electron Microscope with Energy Dispersive X-ray spectrometer (SEM-EDX) demonstrated biofilm formation and salt deposition on membrane surfaces, which most probably reduced the performance of MDC. Consequently, our results showed that use of 3D-electrodes was a promising improvement to the conventional configurations with 2-D electrodes since removal efficiencies and energy production were comparable for a more compact electrode structure.Article Citation - Scopus: 5Effect of Covid-19 Pandemic on Ambient Air Quality and Excess Risk of Particulate Matter in Turkey(2021) Gören, Ayşegül Yağmur; Genişoğlu, Mesut; Ökten, Hatice Eser; Sofuoğlu, Sait CemilThe COVID-19 pandemic, which has reached 4 million global cases as of March 10, 2020, has become a worldwide problem. Turkey is one of the most affected (9th in the world) country with 139 771 cases. An intermittent curfew policy that differ for three age groups, and an intercity travel ban varying within the country have been implemented. The effects of changes in social life and industrial activity in terms of environmental pollution are not yet known. The short-term effects on PM2.5, PM10, SO2, NO2, NO, NOx, O3 and CO concentrations measured at 51 air quality measurement stations (AQMS) in 11 cities in March – April period of 2020 were statistically compared with that of the previous year. While PM2.5 (9/14 AQMS) and PM10 (29/35 AQMS) concentrations were not significantly affected, NO (12/24 AQMS), NO2 (20/29 AQMS), NOX (17/25 AQMS) concentrations were decreased, SO2 concentrations at half of the AQMSs (11/25) did not show a significant change. There were stations at which higher pollutant concentrations were measured in the study period in 2020 compared to that of 2019. Excess risks associated with PM2.5 and PM10 were estimated to be variable, albeit with a small difference. In conclusion, the heterogeneous actions taken in response to the COVID-19 pandemic resulted in mixed effects on ambient air quality.