Ph.D. Theses
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Browsing Ph.D. Theses by Author "Copty, Nadim."
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Item An integrated land use-hydrological model for the Bartın spring watershed(Thesis (Ph.D.)-Bogazici University. Institute of Environmental Sciences, 2009., 2009.) Öztürk, Melih.; Copty, Nadim.; Saysel, Ali Kerem.The Bartın spring watershed located in northwestern Turkey supplies the water needs of the Bartın, Amasra and nkumu city centers. Although the water is presently adequate for the spring, autumn and winter seasons, the city centers suffer water scarcity in summer seasons. It is widely recognized that land use changes have a significant impact on the water budget of a watershed. The purpose of this study is to model the land use and hydrological processes within the Bartın spring watershed and simulate the water yield under different future land use scenarios. For this purpose, a coupled land use-hydrodynamics model was developed. The land use dynamic simulation model was built using STELLA dynamic simulation platform while the MIKE SHE computer program was used to simulate the hydrodynamics of the watershed. The link between the two models is through the Leaf Area Index (LAI) and Root Depth (RD) parameters which are generated in the land use model and supplied to the hydrodynamics model. The dynamic land use model represents several forest stand groups and land use categories with their respective acreages and their conversions. The model was structurally validated and analyzed through a series of sensitivity tests. It was calibrated with respect to the historical geographical data and the calibration results are quite satisfactory. The calibration target for the hydrodynamics model was the river discharge at the downstream end of the watershed, while the calibration parameters were the saturated hydraulic conductivity of the deeper soil, the threshold melting temperature values and the RD value. The optimal simulation produced correlation coefficients, R=0.72 and R2=0.52 with a mean error of 0.01 m3/s. Sensitivity analyses of the hydrodynamics model indicate that it is quite sensitive to the land use type; complete agricultural cover would yield 25- 33% higher discharge compared to a completely forested watershed. The hydrodynamics model is also sensitive to the LAI up to a value of 3 and becomes insensitive for higher values. The model however, is not strongly sensitive to hydraulic conductivity of the saturated zone.Item Evaluation advanced oxidation technologies and nanoscale particles for water and groundwater remediation(Thesis (Ph.D)-Bogazici University. Institute of Environmental Sciences, 2008., 2008.) Aksoy, Dila.; İnce, Nilsun.; Copty, Nadim.Advanced Oxidation Processes (AOP) that are based on the in-situ generation of hydroxyl radicals in solution are extremely powerful tools for the destruction of recalcitrant compounds in water and groundwater. Recent research has shown that subsurface injection of nanoparticles may also be a viable technology for the in-situ remediation of contaminated groundwater resources. The purpose of this study was to assess the degradability of typical groundwater contaminants, namely phenol and 2-chlorophenol by advanced oxidation processes, nanoparticles and combinations thereof. Advanced oxidation processes investigated were ozonation, UV irradiation, sonolysis, and sono-Fenton process. In the second part of the research, flow-through reactors were used to test the mobility of the selected nanoparticle solutions in porous media under different flow configurations. Continuous flow experiments mainly focused on the assessment of the mobility of nanoparticle solutions in porous media under different flow configurations. Comparison of the nanoparticle breakthrough curves to that of the conservative tracers showed that the transport of nanoparticles is influenced by their concentration, which strongly controls the particle size and hence, their mobility. Overall, this study has demonstrated that phenolic compounds in contaminated water and groundwaters may be effectively destroyed by use of optimized hybrid processes involving Advanced Oxidation Processes and nanoparticles.|Keywords: advanced oxidation, ultrasound, nanoparticle, groundwater remediation, phenolic compoundsItem Remediation of DNAPLs in saturated porous media: Cosolvent flushing and sherwood correlation(Thesis (Ph.D.) - Bogazici University. Institute of Environmental Sciences, 2018., 2018.) Aydın, Derya.; Copty, Nadim.The contamination of the subsurface by the accidental release of organic contaminants in the form of non-aqueous phase liquids (NAPLs) is a widespread and challenging environmental problem. However, there is lack of cost effective technologies for the remediation of groundwater systems contaminated with NAPLs. A key process influencing the effectiveness of NAPL remediation is the interphase mass transfer which is the transfer of components across the interface separating the aqueous and NAPL phases. This study evaluates the use of cosolvent flushing for the removal of NAPLs from saturated porous media. Intermediate-scale laboratory experiments were conducted to investigate the impact of cosolvent content, flow velocity, and pumping pattern on cosolvent enhanced NAPL dissolution. Results demonstrated the importance of the flushing solution content and the flow characteristics on NAPL removal. The experimental results were also modeled using multiphase flow simulator. The model results highlighted the significance of the interphase mass transfer in NAPL remediation and the need to model this process as a non-equilibrium kinetic process. To further elucidate the factors influencing the interphase mass transfer mechanism, a series of controlled dissolution experiments from pooled NAPL were also conducted. The interpretation of the experiments was performed using a 2D pore network model in addition to a simplified 1D analytical solution. Results showed that the analytical solution which ignores lateral transport, under-estimates the interphase mass transfer coefficient. Based on the estimated mass transfer coefficients, improved non-lumped Sherwood correlations were developed. These correlations can be used in future modeling studies involved pooled NAPL configurations.