Environmental Engineering / Çevre Mühendisliği
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Article Citation - WoS: 6Citation - Scopus: 6A Novel Land Surface Temperature Reconstruction Method and Its Application for Downscaling Surface Soil Moisture With Machine Learning(Elsevier, 2024) Güngör, Şahin; Gündüz, OrhanDownscaling of soil moisture data is important for high resolution hydrological modeling. Most downscaling studies in the literature have used spatially discontinuous land surface temperature (LST) maps as the main auxiliary parameter, which limits the creation of continuous soil moisture maps. The number of studies on soil moisture downscaling with machine learning that use gapless LST maps is limited. With this motivation, a hybrid reconstruction method has been proposed in this study to practically obtain continuous LST maps, which are then used to produce high resolution surface soil moisture (SSM) datasets. The proposed method is shown to have high mean performance with R2 and RMSE values of 0.94 and 1.84°K, respectively, for the period between 2019 and 2022. The developed reconstructed LST maps were then used to downscale original 9 km spatial resolution soil moisture datasets of SMAP L3 and SMAP L4 with Random Forest (RF) machine learning algorithm. The RF model were run with four different rainfall datasets, and the MSWEP rainfall dataset was found to produce the best results. The use of antecedent rainfall values as input variables in machine learning models has been shown to improve the performance of the models R2 0.76 to 0.93. The accuracy of the downscaled data was later evaluated for Western Anatolia Basins (WAB) in Türkiye with 31 in-situ stations. The downscaled SMAP L4 had good average statistical indicators R (0.815 ± 0.1), RMSE (0.09 ± 0.047 cm3/cm3), and ubRMSE (0.058 ± 0.025 cm3/cm3). Downscaled SMAP L3 was also validated with in-situ observations with satisfactory R (0.79 ± 0.074), RMSE (0.09 ± 0.043 cm3/cm3), and ubRMSE (0.06 ± 0.026 cm3/cm3) statistics. Furthermore, the performance of the downscaled SMAP L3 was also cross validated with SMAP + Sentinel 1 (L2) dataset between 2019 and 2022. The mean statistics of R (0.761 ± 0.11) and Root Mean Squared Difference (RMSD) (0.05 ± 0.014 cm3/cm3) between downscaled SMAP L3 and L2 data revealed that the new reconstruction method of LST used in the RF model for downscaling of soil moisture performed well to obtain high resolution soil moisture datasets. The proposed technique also overcame the difficulties associated with coastal regions where data was masked for quality considerations, by not only enhancing overall spatial resolution but also filling these data gaps and giving a complete SSM coverage. © 2024 Elsevier B.V.Article Citation - WoS: 3Citation - Scopus: 4Enhancing Biogas Production From Chicken Manure Through Vacuum Stripping of Digestate(Springer Heidelberg, 2023) Sengur, Ozlem; Akgul, Deniz; Bayrakdar, Alper; Calli, BarisThe vacuum stripping's combined ammonia removal and disintegration effect on chicken manure digestate was evaluated for the first time at different pH values (8.5, 9.5, and 10.5) and temperatures (30, 50, and 70 degrees C). In this way, the potential increase in biogas production by recirculating the vacuum-stripped digestate to the anaerobic digester was determined. Experimental results showed that increasing pH and temperature significantly increase TAN removal, but pH is more effective. A significant portion of the ammonia was removed in the first 30 min. Therefore, a second set of stripping tests was performed for 30 min and at 70 degrees C and pH 10.5. After 30-min tests, a biomethane potential (BMP) assay was performed using the vacuum-stripped digestate to determine how vacuum stripping affects biomethane production. Despite having the lowest disintegration efficiency, the highest biomethane potential (56.2 +/- 29.7 mL CH4/gVS) was obtained with the digestate, which was subjected to vacuum stripping at 70 celcius without pH adjustment, and 48.7% more methane was produced than the control set. The lower residual biomethane potential in vacuum-stripped digestate at pH 9.5 and 10.5 was attributed to Na+ inhibition resulting from high NaOH consumption for pH adjustment.Article Citation - WoS: 14Citation - Scopus: 17Cleaner Production of Biohydrogen Using Poplar Leaves: Experimental and Optimization Studies(Elsevier Sci Ltd, 2024) Goren, A. Yagmur; Kenez, Muratcan; Dincer, Ibrahim; Khalvati, AliBiohydrogen (bioH2) is recognized as a potential carbon-neutral energy vector, and developing novel methods has received increasing attention with a prime goal of producing H2 more efficient and cost effective manner. This study aimed to develop a unique reactor to investigate dark fermentative H2 production from poplar biomass using commercially available and inexpensive microorganism cultures. Therefore, six factors of the Box-Behnken design (BBD) were performed to evaluate the individual and combined effects of operational param-eters: acid concentration (2-10%), biomass concentration (2-10 g), initial pH (5-8), temperature (30-40 degrees C), mixing ratio (150-350 rpm), and microorganism concentration (2-6 g) on bioH2 production. Among the oper-ational parameters, the acid concentration was the most effective parameter on bioH2 production. The bioH2 production increased from 11.33 to 18.15 mg/g biomass with increasing acid concentration from 6 to 10%. Moreover, the optimum levels of operational variables were as follows: acid concentration of 9.9%, biomass amount of 2 g, pH of 6.56, temperature of 35 degrees C, mixing ratio of 345 rpm, and microorganism amount of 4.5 g for the highest bioH2 production of 20 mg/g-biomass according to the experimental design. Consequently, the bioH2 production performance of the dark fermentation process showed that bioH2 production from poplar biomass using commercially available microorganisms had a competitive advantage.Review Citation - WoS: 88Citation - Scopus: 102Comprehensive Review and Assessment of Carbon Capturing Methods and Technologies: an Environmental Research(Academic Press inc Elsevier Science, 2024) Goren, Aysegul Yagmur; Erdemir, Dogan; Dincer, IbrahimA majority of the primary contributors of carbon dioxide (CO2) emissions into the environment have really been out of human-made activities. The levels of CO2 in the atmosphere have increased substantially since the time of the industrial revolution. This has been linked to the use of fossil fuels for energy production, as well as the widespread production of some industrial components like cement and the encroaching destruction of forests. An extreme approach is now necessary to develop the right policies and address the local and global environmental issues in the right way. In this regard, CO2 capturing, utilization, and storage are reliable options that industrial facilities can initiate to overcome this problem. Therefore, we have evaluated the two leading technologies that are used for carbon capture: direct (pre-combustion, post-combustion, and oxy-combustion) and indirect carbon (reforestation, enhanced weathering, bioenergy with carbon capture, and agricultural practices) capturing to provide their current status and progresses. Among the considered processes, the post-combustion techniques are widely utilized on a commercial scale, especially in industrial applications. Technology readiness level (TRL) results have showed that amine solvents, pressure-vacuum swing adsorption, and gas separation membranes have the highest TRL value of 9. In addition, the environmental impact assessment methods have been ranked to evaluate their sustainability levels. The highest global warming potential of 219.53 kgCO(2) eq./MWh has been obtained for the post-combustion process. Overall, through this comprehensive review, we have identified some critical research gaps in the open literature in the field of CO2-capturing methods where there are strong needs for future research and technology development studies, for instance, developing stable and cost-effective liquid solvents and improving the adsorption capacity of commercialized sorbents. Furthermore, some research areas, like novel process design, environmental and economic impact assessment of capturing methods with different chemicals and modeling and simulation studies, will require further effort to demonstrate the developed technologies for pilot and commercial-scale applications.Conference Object 3d Modeling of a Historical Mine Waste Site Using Uav Images: Estimation of Stockpile Volumes(Springer, 2023) Önal, Okan; Gündüz, OrhanIn recent decades, the use of Unmanned Aerial Vehicles (UAV) for land surveying became very popular because of their simplicity and low cost. Aerial images of the site can be used for the reconstruction of the site’s 3D digital model. Once proper calibrations are made, these digital models can be used for several purposes including stockpile volume estimation, stability analyses, forensic engineering and archiving, etc. In this study, the 3D model of an abandoned historical mine waste disposal site located in Balıkesir-Turkey was reconstructed for the estimation of the waste stockpile volumes. The historical mine site is a facility that was abandoned more than 80 years ago. Mine wastes of different quality were disposed of in and around the site along the hydrologically intermittent creek that passes through the site. No engineered precautions were taken at the site to reduce the environmental impacts and all waste piles were exposed to the natural eroding effect of precipitation and wind. The total amount of the waste volume is not known accurately, which prevents researchers to quantify the potential impacts associated with different waste stockpiles. Thus, a 3D digital model of the site was created by using UAV data obtained from a quadcopter and later processed to obtain a digital topography of the site with an improved accuracy value of ± 2 cm. The stockpiles were later analyzed with geographic information systems to characterize the magnitude of mine wastes and to propose alternative engineering solutions for environmental mitigation. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd 2023.Review Citation - WoS: 60Citation - Scopus: 66A Comprehensive Review on Environmental and Economic Impacts of Hydrogen Production From Traditional and Cleaner Resources(Elsevier Sci Ltd, 2023) Goren, A. Yagmur; Dincer, Ibrahim; Khalvati, Ali; Gören, Ayşegül Yağmur; Dinçer, İbrahimThis review paper considered the potential hydrogen (H2) production methods using conventional fossil fuels and in a cleaner manner with biomass and water resources and evaluated them for economic sustainability, environmental impact, and energy efficiency. The study results revealed that the methods of biomass-based hydrogen production (e.g., photo-fermentation (PF), dark fermentation (DF), and microbial electrolysis cell (MEC)), by energy source, appear to more environmentally friendly than the other evaluated methods in terms of emissions since they offer the potential to significantly reduce CO2 releases when their substrates are derived from renewable resources or wastes. Among the biomass-based processes, the PF is the most environmentally friendly H2 production process, presenting a low global warming potential (GWP) value of 1.88 kgCO2 eq./kgH2 and acidification potential (AP) of 0.003 gSO2/kgH2, it is followed by DF and MEC processes. On the other hand, the highest GWP of 19.85 kgCO2 eq./kgH2 and AP 0.139 kgSO2/kg H2 were obtained for the fossil fuel-based gasification process related to coal mining and transportation operations. Although hydrogen production processes seem to consume high amounts of water sources, such as about 9 kg of water consumed for 1 kg of hydrogen produced during conventional electrolysis, the reality is that in the hydrogen ecosystem the water footprint of the process is reduced drastically where hydrogen is employed as fuel in fuel cell systems and converted back to water while generating electricity. So, the hydrogen ecosystem may diligently be recognized as the water conserving cycle. On the other hand, the study results showed that commercially available fossil fuel based (e.g., coal) gasification and steam-methane reforming processes are more advantageous over other lab scale technologies in terms of cost and process efficiency. Nevertheless, rising carbon costs may reduce the reasonable price of fossil-based H2 and promote the cost-competitiveness of biomass-based renewable H2. Overall ranking results also proved that biomass-based H2 production processes are primarily promising options for H2 production in an environmentally friendly and moderately cost-effective way.Review Citation - WoS: 22Citation - Scopus: 30Comparative Environmental Sustainability Assessment of Biohydrogen Production Methods(Elsevier, 2023) Goren, A. Yagmur; Dincer, Ibrahim; Khalvati, Ali; Gören, Ayşegül Yağmur; Dinçer, İbrahimAs energy crisis is recognized as an increasingly serious concern, the topic on biohydrogen (bioH(2)) production, which is renewable and eco-friendly, appears to be a highly-demanding subject. Although bioH(2) production technologies are still at the developmental stage, there are many reported works available on lab- and pilot-scale systems with a promising future. This paper presents various potential methods of bioH(2) production using biomass resources and comparatively assesses them for environmental impacts with a special emphasis on the specific biological processes. The environmental impact factors are then normalized with the feature scaling and normalization methods to evaluate the environmental sustainability dimensions of each bioH(2) production method. The results reveals that the photofermentation (PF) process is more environmentally sustainable than the other investigated biological and thermochemical processes, in terms of emissions, water-fossil-mineral uses, and health issues. The global warming potential (GWP) and acidification potential (AP) for the PF process are then found to be 1.88 kg-CO2 eq. and 3.61 g-SO2 eq., which become the lowest among all processes, including renewable energy-based H-2 production processes. However, the dark fermentation-microbial electrolysis cell (DF-MEC) hybrid process is considered the most environmentally harmful technique, with the highest GWP value of 14.6 kg-CO2 eq. due to their superior electricity and heat requirements. The water conception potential (WCP) of 84.5 m(3) and water scarcity footprint (WSF) of 3632.9 m(3) for the DF-MEC process is also the highest compared to all other processes due to the huge amount of wastewater formation potential of the system. Finally, the overall rankings confirm that biological processes are primarily promising candidates to produce bioH(2) from an environmentally friendly point of view.Article Citation - WoS: 6Citation - Scopus: 6Microbial Desalination Cell Treated Spent Geothermal Brine as a Nutrient Medium in Hydroponic Lettuce Cultivation: Health Risk Assessment(Elsevier, 2024) Goren, A. Y.; Eskisoy, D. N.; Genisoglu, S.; Okten, H. E.The scarcity and contamination of freshwater resources are extremely critical issues today, and the expansion of water reuse has been considered as an option to decrease its impact. Therefore, the reuse of microbial desalination (MDC)-treated spent geothermal brine for agricultural purposes arises as a good solution to prevent water contamination and provide sustainable water usage. In this study, the potential of treated spent geothermal water from MDC system as a nutrient solution for the hydroponic cultivation of lettuce was evaluated. The effects of different water samples (Hoagland solution (R1) as a control, MDC-treated water (R2), 1:1, v/v mixture of MDCtreated water and Hoagland solution (R3), 4:1, v/v mixture of MDC-treated water and Hoagland solution (R4), and tap water (R5)) on lettuce growth were considered. The application of R3 and R4 samples for hydroponic lettuce cultivation was promising since the lettuce plants uptake sufficient nutrients for their growth and productivity with low toxic metal concentrations. In addition, the chlorophyll-a, chlorophyll-b, and carotene contents of lettuce were in the range of 1.045-2.391 mg/g, 0.761-1.986 mg/g, and 0.296-0.423 mg/g in different water samples, respectively. The content of chlorophyll-a was highest in R1 (2.391 mg/g), followed by R3 (2.371 mg/g). Furthermore, the health risk assessment of heavy metal accumulations in the lettuce plants cultivated in the various water samples was determined. Results showed that heavy metal exposure via lettuce consumption is unlikely to suffer noticeable adverse health problems with values below the permissible limit value.Article Occurrence of Bromide and Bromate in Chlorinated Indoor Swimming Pools, And Associated Health Risks(Yildiz Technical University, 2023) Dumanoğlu, Y.; Genisoglu, M.; Sofuoglu, S.C.Swimming is a physical activity that is accessible to people of all ages in all seasons. However, continuous organic and inorganic precursor load and disinfectant dosing make pool water chemistry much more complex than other disinfected waters. Carcinogenic bromate compound is one of the hundreds of disinfection by-products in pool water. The occurrence of bromate in pool waters depends on the precursor content of filling water, the disinfection process, operating parameters, and the purity of disinfectants. While the average filling water bromide concentrations of University Campus indoor swimming pool in Gülbahçe –Urla (SP1) and Buca public indoor swimming pool (SP2) were determined to be 182 μg/L and 11.0 μg/L, respectively, the average bromate concentrations of SP1 and SP2 were 59.4 μg/L and 68.3 μg/L. Estimated chronic-toxic health risks of accidental ingestion of pool water during swimming (between 10-3 and 10-1) were lower than the threshold level (‘1’). Although the carcinogenic risks in central tendency scenario (<10-6) indicate negligible risks for swimmers, worst case scenario indicates carcinogenic risks (medians were ranged from 1.61×10-6 to 9.42×10-6) for highly exposed specific swimmer groups. Bromate accumulation in swimming pools needs attention for mitigating the health risks for swimmers. © 2021, Yıldız Technical University.Article Citation - WoS: 21Citation - Scopus: 21Remote Sensing-Based Monitoring and Evaluation of the Basin-Wise Dynamics of Terrestrial Water and Groundwater Storage Fluctuations(Springer, 2023) Khorrami, Behnam; Gündüz, OrhanThe recent dynamics of terrestrial water storage (TWS) and groundwater storage (GWS) fluctuations were investigated based on the Gravity Recovery And Climate Experiment (GRACE) observations over 25 basins of Türkiye. Coarse-resolution GRACE estimates were downscaled based on the Random Forest algorithm. The impacts of precipitation (P) and evapotranspiration (ET) on the variations of water storage were also assessed. The findings demonstrated good performance for the RF model in simulating finer resolution estimates of TWS. The results indicated a diminishing trend of TWS and its hydrologic components over all the basins from 2003 to 2020. The Doğu Akdeniz Basin with the annually decreasing TWS and GWS of 1.15cm/yr and 1.10cm/yr was the most critical basin of Türkiye. The least storage loss was observed in the Batı Karadeniz Basin with the annual TWS and GWS loss of 0.38cm/yr and 0.45cm/yr , respectively. Based on the results, Türkiye has lost, on average, an estimated 5.16km3/yr and 4.09km3/yr of its TWS and GWS, respectively, which are equivalent to the total storage loss of 92.88km3 and 73.62km3 of TWS and GWS during the last 18 years. The results also indicated that P and ET interact differently with the variations of TWS and GWS. The net water flux was revealed to be partially correlated with the total water storage fluctuations, suggesting the governing role of other deriving forces particularly the anthropogenic factors in the spatiotemporal variations of Türkiye’s water storage; therefore, a sector-specific analysis of the water storage variations is crucial for the country, particularly by concentrating more on the dynamics of GWS. Graphical Abstract: [Figure not available: see fulltext.]. © 2023, The Author(s), under exclusive licence to Springer Nature Switzerland AG.
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