Environmental Engineering / Çevre Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/4321
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Editorial Special Issue on the 4th International Conference on Recycling and Reuse 24–26 October 2018, Istanbul, Turkey: Preface(Elsevier B.V., 2019) Okten, H.E.; Ökten, Hatice Eser; Balkaya, N.; Aydin, S.; Elmaslar, E.; Ongen, A.; Selcuk, H.[No abstract available]Article Citation - WoS: 10Citation - Scopus: 12Removal of Arsenate by Electrocoagulation Reactor Using Aluminum Ball Anode Electrodes(IWA Publishing, 2018) Gören, Ayşegül Yağmur; Öncel, Mehmet Salim; Demirbaş, Erhan; Şık, Emrah; Kobya, MehmetThe aim of this research was to remove arsenate (As(V)) from groundwater using an air-injected electrocoagulation (EC) reactor with aluminum (Al) ball anodes. The effects of seven operating variables - initial pH, applied current (i), operating time (t(EC)), initial As(V) concentration (C-o), Al ball anode diameter (d(p)), reactor column height (h), and airflow rate (Q(air)) were investigated with a Box-Behnken statistical experimental design. ANOVA results from the quadratic model equations indicated that the model fitted very well with the experimental data for the responses, which were removal efficiency, operating cost (OC), As(V) adsorption capacity, and effluent concentration (R-2 >= 0.87). The most effective parameters were applied current, operating time, and anode height for As(V) removal efficiency in the EC reactor, while initial pH, Al anode diameter, and air flow rate had limited effect on removal. The model predicted a residual As(V) concentration below 10 mu g/L under the optimum operating conditions (pH 7.03, 0.29 A, 10.5 min, d(p) 7.5 mm, 613.4 mu g/L, h 5.1 cm, and Q(air) 6.4 L/min). The maximum As(V) removal efficiency and minimum OC in the EC process were almost 99% and 0.442 $/m(3), respectively.Article Citation - WoS: 26Citation - Scopus: 26Multi-Route - Multi-Pathway Exposure To Trihalomethanes and Associated Cumulative Health Risks With Response and Dose Addition(Academic Press Inc., 2019) Genişoğlu, Mesut; Ergi Kaytmaz, Ceyda; Sofuoğlu, Sait CemilCumulative health risk estimation for exposure to mixtures is a current issue, which would present a useful tool for environmental and public health management. Cumulative risks were estimated with response and dose addition methods for individual multi-route - multi-pathway exposure to trihalomethanes and associated carcinogenic toxic risks in Izmir, Turkey. Exposure levels were estimated for ingestion, dermal, and inhalation routes using measured tap water and bottled water THM concentrations. Drinking, showering, hand and dish washing were the considered pathways. THM concentrations in air during the showering were modeled with two-resistance theory using tap water concentration data. The estimated carcinogenic risk levels for ingestion route were in the range of safe (< 10(-6)) to low priority (< 10(-4)), for dermal route all were in the safe zone (< 10(-6)), and for inhalation route were in the range of safe to high priority (> 10(-4)) zones, indicating ingestion and inhalation routes were of similar significance ahead of dermal exposure. Cumulative carcinogenic risks of THM compounds were estimated using simple (response) addition and dose addition using cumulative relative potency factor (CRPF) methods. CRPF method estimated the risks at lower levels compared to the simple addition, which originated from the use two different risk factor values for the index chemical in the method. Cumulative chronic-toxic risks were also assessed, rendering below the threshold risk levels for all routes. This study showed that multi-route - multi-pathway exposure assessment and cumulative risk assessment should together be considered for better environmental and public health management.Article Citation - WoS: 26Citation - Scopus: 34Arsenite Removal From Groundwater in a Batch Electrocoagulation Process: Optimization Through Response Surface Methodology(Taylor & Francis, 2019) Şık, Emrah; Gören, Ayşegül Yağmur; Demirbaş, Erhan; Kobya, Mehmet; Öncel, Mehmet SalimIn this study, influences of seven process variables such as initial pH (pH(i)), applied current (i), operating time (t(EC)), initial As(III) concentration (C-o), diameter of Fe ball anode (d(p)), column height in the electrocoagulation (EC) reactor (h) and airflow rate (Q(air)) for removal of As(III) from groundwater by a new air-fed fixed-bed EC reactor were evaluated with a response surface methodology (RSM). The proposed quadratic model fitted very well with the experimental data for the responses. The removal efficiencies and operating costs were determined to be 99% and 0.01 $/m(3) at the optimum operating conditions (a pH(i) of 8.5, 0.05 A, 4.94 min, d(p) of 9.24 mm, h of 7.49 cm, Q(air) of 9.98 L/min for 50 mu g/L). This study clearly showed that the RSM in the EC process was a very suitable method to optimize the operating conditions at the target value of effluent As(III) concentration (10 mu g/L) while keeping the operating cost to minimal and maximize the removal efficiency.Article Citation - WoS: 15Citation - Scopus: 19Brominated Flame Retardants in a Computer Technical Service: Indoor Air Gas Phase, Submicron (pm1) and Coarse (pm10) Particles, Associated Inhalation Exposure, and Settled Dust(Elsevier Ltd., 2019) Genişoğlu, Mesut; Sofuoğlu, Aysun; Kurt Karakuş, Perihan Binnur; Birgül, Aşkın; Sofuoğlu, Sait CemilBrominated flame retardants (BFRs) are found in multi-media indoors, therefore, may pose serious risks to human health. This study investigated the occurrence of BFRs in particulate matter (PM1 and PM10) and gas phase by active and passive sampling, and settled dust to estimate potential exposure in a computer technical service. Polybrominated diphenyl ethers (PBDEs) and their alternatives (novel BFRs, NBFRs) were studied. PM and gas phase were collected on glass fiber filters and polyurethane foam plugs, respectively, and analyzed with a GC/MS after extraction, clean-up, and concentration. Inhalation exposure of the staff was estimated based on the measured concentrations using Monte Carlo simulation. BDE-209 was the dominating PBDE congener in all media while bis(2-ethylhexyl)-3,4,5,6-tetrabromophthalate and 1,2-bis(2,4,6-tribromophenoxy)ethane were those of NBFRs. Submicron particulate matter (PM1) BFR levels constituted about one half of the PM10-associated concentrations, while average PM10 mass concentration (69.9 μg m−3) was nine times that of PM1 (7.73 μg m−3). Calculated log10 dust-gas and PM-gas partitioning coefficients ranged from −5.03 to −2.10, −2.21 to −0.55, and −2.26 to −1.04 for settled dust, PM10, and PM1, respectively. The indoor/outdoor concentration ratios were >1 for all compounds indicating the strength of indoor sources in the service. The estimated potential inhalation exposures, for future chronic-toxic and carcinogenic risk assessments, indicated that the levels of gas-phase and PM1-associated exposures were similar at approximately one half of PM10-associated levels. Results of this study indicate that the occurrence of BFRs in all studied media should be taken into consideration for occupational health mitigation efforts.Article Citation - WoS: 2Citation - Scopus: 2A Deterministic and Stochastic Assessment for Exposure and Risk of Arsenic Via Ingestion of Edible Crops(Springer Verlag, 2019) Can Terzi, Begüm; Gündüz, Orhan; Sofuoğlu, Sait CemilNatural arsenic contamination is a critical problem for various places around the world. Simav Plain (Kutahya, Turkey) is one such area that was shown to have natural arsenic contamination in its waters and soils. Arsenic exposure through ingestion of edible crops cultivated in Simav Plain and associated health risks were assessed in this study. To achieve this objective, arsenic levels in 18 crop species were estimated based on measured soil arsenic concentrations. Individual and aggregate non-carcinogenic and carcinogenic risks associated with ingestion of arsenic-contaminated crops were then assessed with scenario-based deterministic point estimates and stochastic population estimates. Monte Carlo simulation was used for the estimation of population health risks. Accordingly, wheat was found as the highest-ranked crop specie for the both types of health risks, followed by tomato and potato, which are three of the most consumed crops in the region. The risk levels estimated in this study were relatively high, indicating consumption of crops grown in the plain may be posing significant health risks even at lower-bound estimates. Consuming wheat, tomato, potato, and their products from uncontaminated sources was found to reduce the aggregate risks up to 88% implicating the importance of proposing suitable management measures for similar risk-prone areas.Article Citation - WoS: 27Citation - Scopus: 28Fast Formation of Nitro-Pahs in the Marine Atmosphere Constrained in a Regional-Scale Lagrangian Field Experiment(American Chemical Society, 2019) Mulder, Marie D.; Dumanoğlu, Yetkin; Efstathiou, Christos; Kukucka, Petr; Matejovicova, Jana; Maurer, Christian; Pribylova, Petra; Prokes, Roman; Sofuoğlu, Aysun; Sofuoğlu, Sait Cemil; Wilson, Jake; Zetzsch, Cornelius; Wotawa, Gerhard; Lammel, GerhardPolycyclic aromatic hydrocarbons (PAHs) and some of their nitrated derivatives, NPAHs, are seemingly ubiquitous in the atmospheric environment. Atmospheric lifetimes may nevertheless vary within a wide range, and be as short as a few hours. The sources and sinks of NPAH in the atmosphere are not well understood. With a Lagrangian field experiment and modeling, we studied the conversion of the semivolatile PAHs fluoranthene and pyrene into the 2-nitro derivatives 2-nitrofluoranthene and 2-nitropyrene in a cloud-free marine atmosphere on the time scale of hours to 1 day between a coastal and an island site. Chemistry and transport during several episodes was simulated by a Lagrangian box model i.e., a box model coupled to a Lagrangian particle dispersion model, FLEXPART-WRF. It is found that the chemical kinetic data do capture photochemical degradation of the 4-ring PAHs under ambient conditions on the time scale of hours to 1 day, while the production of the corresponding NPAH, which sustained 2-nitrofluoranthene/fluoranthene and 2-nitropyrene/pyrene yields of (3.7 ± 0.2) and (1.5 ± 0.1)%, respectively, is by far underestimated. Predicted levels of NPAH come close to observed ones, when kinetic data describing the reactivity of the OH-adduct were explored by means of theoretically based estimates. Predictions are also underestimated by 1-2 orders of magnitude, when NPAH/PAH yields reported from laboratory experiments conducted under high NOx conditions are adopted for the simulations. It is concluded that NPAH sources effective under low NOx conditions, are largely underestimated.Article Citation - WoS: 8Citation - Scopus: 12A Box–behnken Design (bbd) Optimization of the Photocatalytic Degradation of 2,4-Dichlorophenoxyacetic Acid (2,4-D) Using Tio2/H2o2(Desalination Publications, 2018) Doğdu Okçu, Gamze; Baldan Pakdil, Nazlı; Ökten, Hatice Eser; Yalçuk, Arda2,4-Dichlorophenoxyacetic acid (2,4-D), a chlorinated phenoxy-alkanoic herbicide, is used extensively in agriculture. This work investigates TiO2/H2O2 mediated UV photocatalytic degradation of 2,4-D in a laboratory-scale photoreactor. Three levels of Box–Behnken design technique, combined with response surface methodology (RSM), were used to design the experiments. Two kinds of multivariate experimental design (pH, TiO2, and 2,4-D concentration) and (pH, TiO2, and H2O2 concentrations) were employed to establish two quadratic models (Model 1 and Model 2), showing the functional relationship between degradation rate of 2,4-D and three independent experimental parameters. Model 1 predicted optimum values for pH, TiO2, and 2,4-D concentrations to be 5.7, 1.20 g L−1, and 32 mg L−1, respectively. Model 2 predicted optimum values for pH, TiO2, and initial H2O2 concentrations to be 4.94, 1.34 g L−1, and 161 mg L−1. Degradation rate of 2,4-D approached 78.10% for Model 1 and 83.63% for Model 2. For both models, similar results were obtained through optimizing variables by RSM and using single factorial batch reactor operation. Regression analysis showed good agreement between experimental results and predictive values for Models 1 and 2, with R2 values of 0.9958 and 0.9976, respectively.Article Citation - WoS: 4Citation - Scopus: 7Heterogeneous Photocatalytic Degradation and Mineralization of 2,4-Dichlorophenoxy Acetic Acid (2,4-D): Its Performance, Kinetics, and Economic Analysis(Desalination Publications, 2019) Doğdu Okçu, Gamze; Ökten, Hatice Eser; Yalçuk, ArdaThe photocatalytic degradation and mineralization of commercial solution of 2,4-dichlorophenoxy-acetic acid (2,4-D) was carried out by UVA/P25 TiO 2 and UVA/P25 TiO 2 /H 2 O 2 oxidation processes under batch-mode conditions. In UVA + TiO 2 photocatalysis (TiO 2 1.5 gL −1 , pH 5, initial 2,4-D 25 mg L −1 ), 97.47% ± 0.27% degradation, 39.89% ± 3.42% mineralization, and 65.52% ± 4.88% oxidation were achieved in 180 min, and in UVA +TiO 2 + H 2 O 2 photocatalysis (TiO 2 1.5 g L −1 , pH 5, initial 2,4-D 25 mg L −1 , H 2 O 2 150 mg L −1 ), 99.74% ± 0.08% degradation, 55.99% ± 2.67% mineralization, and 82.49% ± 1.90% oxidation were obtained in 180 min. The pseudo-first-order kinetic model fitted the experimental data well, and the photocatalytic degradation process was explained by the modified L–H model; k c and K LH were 1.293 mg L −1 min −1 and 0.232 L mg −1 , respectively. Fourier transform infrared (FTIR) spectroscopy spectra and scanning electron microscopy (SEM) analysis indicated degradation of organic bonds of the herbicide and adsorption of 2,4-D particles onto the TiO 2 catalyst during 24-h experiments. Moreover, the dependence of k app on the half-life time was determined by calculating the electrical energy per order (E EO ). UVA/TiO 2 /H 2 O 2 photocatalysis may be applied as a pretreatment to 2,4-D herbicide wastewater at a pH of 5 for biological treatment.Article Citation - WoS: 3Citation - Scopus: 4Use of Nano Zero-Valent Iron Coated Coffee Grounds for Removal of Zn(ii) and Ni(ii) From Aqueous Solutions(Desalination Publications, 2019) Gören, Ayşegül Yağmur; Genişoğlu, Mesut; Ökten, Hatice EserThis research investigates the adsorption capacity of a novel composite material, namely nano zero-valent iron coated coffee grounds (nZVI-CG), for removal of zinc (Zn) and nickel (Ni). nZVI particles were synthesized and immobilized to the surface of waste coffee grounds (CG) using the ultrasonic-assisted liquid phase method. Characterization of synthesized nZVI-CG composite and bare CG showed that nZVI coating has increased the surface area significantly. Batch tests were conducted to examine the effects of pH, reaction time and initial metal concentrations on Zn2+ and Ni2+ removal. At an initial metal concentration of 10 mg-Ni/L and 10 mg-Zn/L, nZVI-CG removal rates for Zn2+ and Ni2+ were observed as 98.89% and 97.29%, respectively; while removal rates of bare CG have remained at 51% (Zn2+) and 48.1% (Ni2+). Moreover, acidic conditions were observed to deteriorate Ni2+ and Zn2+ adsorption since most functional groups of the metals were protonated. Increasing initial nickel and zinc concentrations decreased removal rates. While the model fittings improved with increasing pH, in the case of nZVI-CG, Langmuir isotherm gave the best fits for Ni2+ and Zn2+ at pH 5 and 7. Also, our experimental results followed the pseudo-second-order kinetic model, regardless of the used adsorbent. Consequently, our results showed that nZVI-CG composite material is a promising alternative adsorbent for pilot scale metal removal/recovery applications.
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