Environmental Engineering / Çevre Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/4321
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Article Citation - WoS: 20Citation - Scopus: 24Lime-Activated One-Part Geopolymer Mortars From Construction, Demolition and Industrial Wastes(Elsevier, 2024) Kogbara, Reginald B.; Al-Zubi, Abdelrahman; Mortada, Youssef; Hammoud, Ahmad; Masad, Eyad A.; Khraisheh, Marwan K.This work focused on the production of one-part geopolymer mortars from construction and demolition wastes (CDW) blended with steel slag. Previous related studies on geopolymer production from CDW utilized conventional two-part geopolymers comprised of highly alkaline activator solutions and CDW materials. Thus, the study's significance consists in producing high-strength (≥35 MPa) ambient-cured mortars from CDW with predominantly concrete waste by replacing conventional highly alkaline activator solutions with an environmentally-friendly alkaline activator, Ca(OH)2 powder. Four mortar mixtures were produced with CDW contents ranging from 50 to 65 % dry weight, varying the brick waste content from 3 to 18 %. The effect of elevated temperature (40 °C) curing was also considered. The results showed that 55 % CDW content had optimum performance across all parameters studied such as compressive and flexural strengths, setting time, as well as changes in nuclear magnetic resonance (NMR)-determined pore structure (porosity and mean pore size) and x-ray diffraction (XRD)-determined degree of crystallinity over time. It had 28-day compressive and flexural strengths of 42 and 5.8 MPa, respectively, and initial and final setting times of 25 and 50 min. The importance of sufficient brick waste content in the geopolymer mixtures for effective mechanical performance is highlighted. The inclusion of concrete waste in powder form reduced compressive strength under ambient curing but improved performance at 40 °C curing. It is concluded that sustainable structural mortars can be produced by ‘just adding water’ to an optimized CDW mixture with predominantly concrete waste blended with brick waste and slag and activated by powdered Ca(OH)2. © 2023 The AuthorsArticle Citation - WoS: 5Citation - Scopus: 5Screening Diatom Strains Belonging To Cyclotella Genus for Chitin Nanofiber Production Under Photobioreactor Conditions: Chitin Productivity and Characterization of Physicochemical Properties(Elsevier, 2023) Özkan, AltanDiatom species belonging to Cyclotella and Thalassiosira genera have the unique and industrially relevant ability to biosynthesize and extrude pure chitin nanofibers. The current understanding of diatom-based chitin production is narrowed by the complete reliance on the performance of a single strain. This study aims to facilitate the development of a wider understanding for enhanced industrial utility. For this purpose, six Cyclotella strains were cultivated under standardized process conditions of a bubble column photobioreactor, and the resulting productions were characterized in terms of rate and physicochemical properties. A two-stage cultivation protocol was followed where the cells were cultivated under silicon replete and then following its complete consumption under silicon deplete conditions. All the strains produced chitin fibers of β-form with relatively constant average diameters, ranging from 48 to 58 nm. Chitin production rates and final concentrations as well as fiber number densities and length distributions were highly strain-dependent. Dissolved silicon availability controlled chitin biosynthesis: following its depletion, the productivity of all the strains increased drastically. Two strains of marine origin, C. cryptica CCMP 332 and C. cryptica CCMP 333, generated the most favorable outcomes for commercial-scale production and had final concentrations of 272 ± 9 mg/L and 316 ± 12 mg/L, and maximum production rates of 48 ± 2 mg/L-day and 51 ± 2 mg/L-day, respectively. The superior performance of these strains was due to (i) the extrusion of more fibers per fiber port, in the case of C. cryptica CCMP 333 as many as 20.7 ± 1.0. indicating free fiber accumulation in suspension, and (ii) the biosynthesis of longer fibers, mean fiber lengths varied from 15 to 20 μm during cultivation. This study demonstrates the importance of species selection and silicon availability for diatom-based chitin production in terms of rate, final concentration, and nanofiber fiber length distributions.Article Citation - WoS: 31Citation - Scopus: 34Insights Into Engineered Graphitic Carbon Nitride Quantum Dots for Hazardous Contaminants Degradation in Wastewater(Elsevier, 2023) Gören, Ayşegül Yağmur; Recepoğlu, Yaşar Kemal; Vatanpour, Vahid; Yoon, Yeojoon; Khataee, AlirezaIncreased environmental pollution is a critical issue that must be addressed. Photocatalytic, adsorption, and membrane filtration methods are suitable in environmental governance because of their high selectivity, low cost, environment-friendly nature, and excellent treatment efficiency. Graphitic carbon nitride (g-C3N4) quantum dots (QDs) have been considered as photocatalysts, adsorbents, and membrane materials for wastewater treatments, owing to their stability, adsorption capacity, photochemical properties, and low toxicity and cost. This review summarizes g-C3N4 QD synthesis techniques, operating parameters affecting the removal performance in the treatment process, modification effects with other semiconductors, and benefits and drawbacks of g-C3N4 QD-based materials. Furthermore, this review discusses the practical applications of g-C3N4 QDs as adsorbents, photocatalysts, and membrane materials for organic and inorganic contaminant treatments and their value-added product formation potential. Modified g-C3N4 QD-based material adsorbents, photocatalysts, and membranes present potentially applicable effects, such as removal of most waterborne contaminants. Excellent results were obtained for the reduction of methyl orange, bisphenol A, tetracycline, ciprofloxacin, phenol, rhodamine B, E. coli, and Hg. Overall, this paper provides comprehensive background on g-C3N4 QD-based materials and their diverse applications in wastewater treatment, and it presents a foundation for the enhancement of similar unique materials in the future.Article Citation - WoS: 11Citation - Scopus: 12Investigation of the Best Possible Methods for Wind Turbine Blade Waste Management by Using Gis and Fahp: Turkey Case(Springer, 2022) Öztürk, Samet; Karipoğlu, FatihThe aim of this study is to present the status and projections of wind turbine blade retirement in Turkey; to investigate the number of retiring WT blades in the regional, manufacturer, and material aspects; and to discuss the management methods for retired WT blades. To determine the best possible wind turbine blade waste management methods for Turkey, a combined application of Geographical Information Systems (GIS) and the Fuzzy Analytical Hierarchy Process (FAHP) is used in this study. It is found that around nine thousand WT blades will become waste between 2020 and 2039 in Turkey, corresponding to around 80,500 tons of waste. On average, 52,325 tons of glass/carbon and 28,175 tons of polymers will be accumulated between 2020 and 2039 from wind turbine blades. More than half of the WT blade waste will come from two WT manufacturers, namely, Enercon and Nordex. Aegean and Marmara regions will provide 74% of the blade waste, where 33% of them will be 2 MW and 2.5 MW sizes of WT blades. Furthermore, a case study is applied to Izmir city to demonstrate the results of FAHP for finding the best available method to dispose of WT blades. The results show that using blade waste as filling material is the best alternative, while waste-to-energy is the last favorable option for blade waste management. Finally, sensitivity analyses are applied to demonstrate the robustness of the results for the inclusion of new alternatives and the bias of experts’ judgments.Article Citation - WoS: 10Citation - Scopus: 14Indoor Environmental Quality in Naturally Ventilated Schools of a Dusty Region: Excess Health Risks and Effect of Heating and Desert Dust Transport(Wiley, 2022) Şahin, Çağrı; Rastgeldi Doğan, Tuba; Yıldız, Melek; Sofuoğlu, Sait CemilIndoor air quality (IAQ) is impacted by polluted outdoor air in naturally ventilated schools, especially in places where both anthropogenic and natural sources of ambient air pollution exist. CO2, PM2.5, PM10, temperature, relative humidity (RH), and noise were measured in five naturally ventilated primary schools in City of Sanliurfa, in a dusty region of Turkey, Southeast Anatolia. Excess risk levels were estimated for particulate matter. Investigation was conducted through an educational year including two seasons in terms of anthropogenic effect, that is, heating/non-heating, and natural effect, that is, desert dust transport/non-dust transport. The median CO2 concentration was measured to be >1000 ppm in all seasons/schools. Temperature and RH fell out of the comfort zone in October-December, during which pollutant concentrations were considerably increased, specifically in November, that heating and dust transport periods coincide. The overall mean indoor PM10 and PM2.5 levels were 58 and 31.8 mu g/m(3), respectively. Risk assessment indicate that both short (incidence of asthma symptoms in asthmatic children) and long-term (prevalence of bronchitis) effects are considerable with 10.9 (2.4-19.6)% and 19.5 (2.2-38.8)%, respectively. The findings suggest that mechanical ventilation retrofitting with particle filtration is needed to mitigate potential negative health consequences on children.Article Citation - WoS: 11Citation - Scopus: 13A Systematic Assessment of Flooding Potential in a Semi-Arid Watershed Using Grace Gravity Estimates and Large-Scale Hydrological Modeling(Taylor & Francis, 2022) Khorrami, Behnam; Fıstıkoğlu, Okan; Gündüz, OrhanThe emergence of the Gravity Recovery And Climate Experiment (GRACE) paved the way for remote tracking of hydrological water cycle components at large scales. With the main motivation of evaluating the feasibility of the coarse resolution GRACE data for small-scale analysis, the GRACE data and large-scale hydrological models were utilized in an integrated manner to monitor the variations of the flood potential index (FPI) over the Western Anatolian Basin (WAB). The results show an ascending trend for monthly and annual FPI over the WAB. The results also suggest that the monthly FPI in 2015, 2003, 2009, and 2016 was the highest, from which the highest potentiality of flood appertains to 2015/07 with an FPI of 0.92. The lowest and highest annual FPI is 0.26 (in 2007) and 0.76 (in 2015), respectively. The validation of the results indicates that variations of FPI coincide with that of the flood incidents, stream discharge, Standardized Precipitation Index (SPI), and the simulated flood risk. The findings accentuate the high feasibility of the GRACE JPL Mascons for better surveillance of floods over local scale areas. Highlights The coarse resolution GRACE JPL mascon functions very well in tracing the spatio-temporal characteristics of flood incidents over local scales. There is an ascending trend in the variations of flood potential over the Western Anatolia Basin (WAB). The WAB has experienced its lowest and highest possibility of flooding in 2007 and 2015 with an average FPI of 0.26 and 0.76, respectively. The variations of the flood potential index (FPI) coincides with that of the reported flood incidents, stream discharge, Standardized Precipitation Index (SPI), and the simulated flood risk.Article Citation - WoS: 36Citation - Scopus: 38Detection and Analysis of Drought Over Turkey With Remote Sensing and Model-Based Drought Indices(Taylor & Francis, 2022) Khorrami, Behnam; Gündüz, OrhanUnder the severe impacts of climate change, drought has become one of the most undesirable and complex natural phenomena with critical consequences for the environment, economy and society. The orthodox drought monitoring approaches use observations of meteorological stations, which are typically restricted in time and space. Remote sensing, conversely, provides continuous global coverage of a variety of hydro-meteorological variables that are influential in drought, and data extracted from remote sensing and modeling missions are now considered more practical and alluring for researchers. In this study, we applied a combination of field data, remotely sensed data and modeled data to detect and quantitatively analyze drought phenomena. To achieve this objective, we utilized Terrestrial Water Storage Anomalies (TWSA) estimations from GRACE mission, Normalized Difference Vegetation Index (NDVI) from MODIS mission, Surface Runoff (R) and Evapotranspiration from ERA5 reanalysis datasets and Soil Moisture (SM) from GLDAS data model to evaluate their feasibility in detecting recent droughts over Turkey. We validated the accuracy of several remote sensing-based indices (GRACE Drought Severity Index, Water Storage Deficit Index [WSDI], Soil Moisture Index, Standardized Runoff Index and NDVI) with the traditional indices (SPI and SPEI) calculated from in situ observations of precipitation. The results revealed that the GRACE-based WSDI gave the best performance with high correlations with the SPI index both temporally and spatially over Turkey. We also found that monthly and annual time series of WSDI agreed well with the SPI index with correlations of 0.69 and 0.73, respectively. The results of drought analysis also indicated that WSDI could be used as a proxy to standard meteorological drought indices over Turkey as it performed well to detect and characterize the recent droughts of Turkey based on its comparisons to SPI results.Article Citation - WoS: 4Citation - Scopus: 5Radiological Modeling of the Impacts of the Chernobyl Nuclear Power Plant Accident on Turkey and Southwest Asia(Elsevier, 2022) Bilgiç, Efem; Gündüz, OrhanMany studies investigated the impacts of the Chernobyl Nuclear Power Plant accident on Europe. However, majority of these have spatially excluded the highly populated southeast region of Chernobyl, including countries such as Turkey, Armenia, Georgia and Iran. In this study, a comprehensive environmental and radiological analysis were conducted particularly for this region. For this purpose, atmospheric dispersion and ground deposition of radionuclides were estimated using a Lagrangian particle dispersion model, FLEXPART. Totally, six simulations were conducted and model results were validated with measurements from Europe and Turkey. Furthermore, total effective dose equivalent (TEDE) values were estimated for adults and infants using the most current dose conversion factors of ICRP. Highest deposition of 137Cs were found in around Eastern Black Sea areas (10–40 kBq/m2). Similar values were found in some locations of Armenia and Azerbaijan under some scenarios, but country averages of 137Cs deposition were lower than 10 kBq/m2 for both countries. No significant depositions were found in southwest Iran, but relatively higher depositions (2–10 kBq/m2) of 137Cs were estimated along the Turkish border. Although there were slightly higher values in northern areas of Syria, Iraq, Lebanon and Cyprus, 137Cs depositions were mostly less than 2 kBq/m2. The 1-year TEDE value was calculated less than 1 mSv throughout the model domain except for some regions of eastern Black Sea. Highest values in lifetime dose values were calculated along the Black Sea coasts of Turkey and Georgia. Overall, infants were affected more from ionizing radiation compared to adults in this region.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: 32Citation - Scopus: 36A Review of Boron Removal From Aqueous Solution Using Carbon-Based Materials: an Assessment of Health Risks(Elsevier, 2022) Gören, Ayşegül Yağmur; Recepoğlu, Yaşar Kemal; Karagündüz, Ahmet; Khataee, Alireza; Yoon, YeojoonCarbon-based compounds have gained attention of researchers for use in boron removal due to their properties, which make them a viable and low cost adsorbent with a high availability, as well as environmental friendliness and high removal efficiency. The removal of boron utilizing carbon-based materials, including activated carbon (AC), graphene oxide (GO), and carbon nanotubes (CNTs), is extensively reviewed in this paper. The effects of the operating conditions, kinetics, isotherm models, and removal methods are also elaborated. The impact of the modification of the lifetime of carbon-based materials has also been explored. Compared to unmodified carbon based materials, modified materials have a significantly higher boron adsorption capability. It has been observed that adding various elements to carbon-based materials improves their surface area, functional groups, and pore volume. Tartaric acid, one of these doped elements, has been employed to successfully improve the boron removal and adsorption capabilities of materials. An assessment of the health risk posed to humans by boron in treated water utilizing carbon-based materials was performed to better understand the performance of materials in real-world applications. Furthermore, the boron removal effectiveness of carbon-based materials was evalu ated, as well as any shortcomings, future perspectives, and gaps in the literature.