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Öğe DENITRIFICATION OF NITRATE BY COMBINED ULTRASOUND AND ZERO VALENT MAGNESIUM AT pH CONTROLLED CONDITIONS(Yildiz Technical Univ, 2015) Ileri, Burcu; Apaydin, Omer; Ayyildiz, OnderIn this study, ultrasound (US), zero-valent magnesium (Mg-0) and their simultaneous combination were tested at different Mg-0 doses (0.5, 1, 1.5, 2 ve 2.5 g/L), pH values (2, 4, 7 ve 9) and ultrasonic powers (30, 60 ve 90 W) for nitrate reduction. Ultrasound alone was found to be ineffective for nitrate removal at different pH values. Effect of ultrasonic power for pH controlled operation, nitrate reduction was increased with increasing dose of magnesium powder. Ultrasound induced profound effects on denitrification capacity of magnesium particles. For example, with controlling pH at 4, 95% of initial nitrate was reduced by 2.5 g/L of magnesium powder within 60 min, while keeping the applying combined US/Mg-0 for 30, 60, and 90 W ultrasonic powers at the same dose, required durations to achieve at the same nitrate removal efficiencies were determined to be approximately 30, 20 and 20 min, respectively. When pH was controlled at 7 and 9, up to 70% of nitrate was removed by 2.5 g Mg-0/L dose after 60 min, but in the same conditions with 90 W ultrasonic power a complete nitrate reduction was attained only within 30 min. Effect of ultrasonic on magnesium surface activation and nitrate removal was arised more clearly at alkaline conditions, when particle surface passivation was increased at increased pH. Nitrogen gas (N-2), nitrite (NO2-) and ammonium/ammonia (NH4+/NH3) were detected as the major denitrification by-products following US/Mg-0 treatment. As more ultrasonic power and magnesium dose were applied, the rate of conversion of nitrate to nitrogen gas increased significantly.Öğe Effect of ultrasonic pretreatment on chlorine dioxide disinfection efficiency(Elsevier, 2011) Ayyildiz, Onder; Sanik, Serdar; Ileri, BurcuUltrasound (US) and chlorine dioxide (ClO2) were combined sequentially in an aim to improve wastewater disinfection. Results demonstrated that the combined effect of US and ClO2 on Escherichio coli (E. coli) and total coliform (TC) inactivation in raw wastewater was synergistic involving high removal of bacteria from the solution. A sequential combination of US (150 or 300 W/L) and ClO2 (2 mg/L) provided about 3.2-3.5 log reduction in the number E. coli and TC in raw wastewater, while the sum of log reductions by the individual treatments were 1.4-1.9. However, the measured inactivation rate with the combination of ultrasound and ClO2 in synthetic wastewater or secondary effluent was the same as the sum of the log inactivations with individual treatments. The enhancement attained by combined US and ClO2 disinfection methods was attributed to the presence of high concentration of particles in raw wastewater and their break up under shock sound waves. (C) 2010 Elsevier B.V. All rights reserved.Öğe Heavy Metal Accumulation, Biomarker Responses and Sensitivity to Oxidative Stress in Isopoda Asellus aquaticus from Saricay Creek (Canakkale-Turkey)(Foundation Environmental Protection & Research-Fepr, 2014) Kaya, Hasan; Akbulut, Mehmet; Selvi, Kahraman; Ileri, Burcu; Duysak, MugeIn this study, the possible oxidative stress that water pollution may cause to Asellus aquaticus is evaluated using the physico-chemical parameters, the heavy metal concentration in the water, and organism and biochemical responses in the living organisms being combined together. For this purpose, the A. aquaticus samples are collected by choosing three stations along the Saricay Creek, some of whose regions are exposed to domestic and industrial pollution. Sampling stations are chosen from regions that are interpreted as polluted or clean according to the heavy metal content and physico-chemical parameters where the A. aquaticus individuals live. After the determination of species is performed, the heavy metal (Cu, Fe, Cd, Pb, and Zn) and biomarker (Na+/K+-ATPase, Glutathione, and TBARS) analyzes were made. According to the water quality analysis, S3 was the most polluted station, S2 was a moderately polluted station, and Si was determined as a clean station. A considerable increase in the amount of glutathione (GSH) was detected in the S2 and S3 stations in parallel with the increase of pollution. However, there were no statistical differences in the TBARS levels as an indicator of lipid peroxidation and Na+/K+-ATPase enzyme activity. The significant increase (three-fold) of the GSH levels in the polluted areas indicates that water pollution causes oxidative stress in the A. aquaticus species. These results show that ecological, physico-chemical, and biochemical parameters can be used together to identify and evaluate the water pollution in rivers that are exposed to pollution.Öğe Impacts of water organic load on chlorine dioxide disinfection efficacy(Elsevier, 2009) Ayyildiz, Onder; Ileri, Burcu; Sanik, SerdarThis study has examined the bactericidal effect of chlorine dioxide in untreated artificial and domestic wastewaters and secondary effluent of various organic loads. Results indicated that the inactivation of Escherichia coli in artificial wastewater was similar with that in real municipal wastewater. Among three waters, the bactericidal effect of chlorine dioxide was lowest in secondary effluent. The bacteria log inactivation increased by up to threefold when the COD concentration of raw wastewater was decreased by half. An unfavorable COD effect was also observed for the disinfection of secondary effluent. To explain the COD effect on bacteria inactivation, chlorine dioxide residuals were measured with time through each disinfection process. Results from statistical analyses have revealed that, in comparison to the correlations using CT values, the inactivation data can be better correlated with the ratio of COD to ClO2 concentrations. The results of this study would be a useful guide for many municipalities and communities in determining chlorine dioxide dosages for water and wastewater disinfection systems. (C) 2009 Elsevier B.V. All rights reserved.Öğe Metal removal from acid mine lake using ultrasound-assisted modified fly ash at different frequencies(Springer, 2020) Ileri, Burcu; Sanliyuksel Yucel, DenizAcid mine drainage/lakes (AMD/AMLs) have a low pH with high concentrations of metals and sulfate and have been a major environmental problem in the Can Coal Basin, in northwestern Turkey. In this study, metal removal from Hayirtepe AML by using fly ash (FA) and modified fly ash (MFA) was investigated in batch experiments. The effects of various parameters, such as ultrasonic frequency, dose, contact time, pH, and temperature, were examined to determine the optimum conditions for metal removal from AML. This study also focused on the application of ultrasound-assisted modification by using a 20-kHz ultrasonic probe and a 40-kHz ultrasonic bath to increase the FA surface and improve its adsorption capacity for metal removal. FA modification at 20 kHz showed better results than that at 40 kHz because it produced rapid bubble implosion with acoustic cavitation. The FA and MFAs selectivity for metal removal was 98%-99% for Fe, 96%-99% for Al, 94%-97% for Zn, 90%-95% for Co, 88%-94% for Ni, 77%-92% for Cu, and 74%-92% for Mn according to the determined optimum parameters. Scanning electron microscopy coupled with the energy-dispersive X-ray spectroscopy (SEM/EDX) and X-ray diffractometry of the solid residues (SRs) identified gypsum as a new mineral phase from sulfate removal from the AML. Inductively coupled plasma mass spectrometry and SEM/EDX analysis revealed that the metal content of the SRs increased. The adsorption process fitted the pseudo-second order kinetic model. Thermodynamic parameters showed that the process was exothermic and the randomness of the solid/solution interface increased during adsorption. Reuse experiments indicated that the MFAs were reused more effectively for metal removal from AML compared with the FA. This study showed that the use of MFAs with a high adsorption capacity and surface area is economic and efficient for metal removal from AML.Öğe Mitigation of Environmental Effects of Anthropogenic Metal Contamination Using Fly Ash(Tmmob Jeoloji Muhendisleri Odasi, 2020) Yucel, Deniz Sanliyuksel; Ileri, BurcuAcid mine drainage (AMD) generated by anthropogenic effects has low pH and contains high concentrations of metals, sulfate, dissolved and suspended solids. The Etili coal mine, located within the Can Coal Basin, northwestern Turkey, has been facing environmental problems caused by AMD since the 1980s. As a result of mining activities, fine grain size mine waste with high sulfur content is distributed over large areas around the coal mines and accelerates the AMD formation process. In this study, the aim was to determine the effect of using the fluidized bed thermal power plant waste of fly ash to neutralize AMD and reduce environmental effects caused by mine wastes at the laboratory scale. Based on the results of chemical analysis, paste pH and acid-base accounting tests, it was identified that mine wastes need to be mixed with at least 30% fly ash by weight in order to prevent AMD production. The leach tests prepared according to the determined optimum mixing ratio showed that as the pH value of leachate increased, the electrical conductivity, metal (Al, Fe, Mn, Ni, Pb and Zn) and sulfate concentrations decreased. At the end of 24 h, the metal concentrations of the leachate fell below the permissible limits in the Turkish Water Pollution Control Regulation and there was no increase in metal concentrations of the leachate during 720 h. At the end of 720 h, reductions of 72-97% were identified for the metal concentrations in leachate. In this research, it was determined that the environmental effects of AMD could be minimized by using fly ash.Öğe Sono-assisted adsorption of acid violet 7 and basic violet 10 dyes from aqueous solutions: Evaluation of isotherm and kinetic parameters(Korean Soc Environmental Engineers - Ksee, 2022) Ileri, BurcuIn this study, the removal of acid violet 7 (AV7) and basic violet 10 (BV10) synthetic dyes was investigated using fly ash alone, ultrasound (40 kHz) alone, and combined ultrasound/fly ash with various experimental parameters such as fly ash dose, contact time, and initial concentration of dye. The adsorption capacity of the ultrasound/fly ash process increased from 5.10 to 7.43 mg g(-1) for AV7, and increased from 5.16 to 7.51 mg g(-1) for BV10 compared with using fly ash alone. The sono-assisted adsorption process was successful in improving the dye uptake capacity with cavitation bubbles and acoustic waves, and thus AV7 and BV10 were removed with a shorter contact time and lower fly ash dose. Obtained regeneration and reuse experiment results showed that the fly ash could be reused for four consecutive cycles of the sono-assisted adsorption process, while fly ash could be reused for two consecutive cycles of the adsorption process. The adsorption kinetics for AV7 and BV10 onto fly ash fitted Lagergren's first-order adsorption kinetic model well. The Langmuir isotherm best described the adsorption with fly ash alone and ultrasound/fly ash process for AV7 and BV10.Öğe Sonocatalytic Reduction of Hexavalent Chromium by Metallic Magnesium Particles(Springer International Publishing Ag, 2016) Ayyildiz, Onder; Acar, Ekrem; Ileri, BurcuThe chemical reduction of hexavalent chromium (Cr(VI)) by combined zerovalent magnesium (ZVMg) and ultrasound (US) was studied under batch conditions. Results have demonstrated that the reduction of Cr(VI) mediated by ZVMg enhanced significantly with the ultrasonic effect. The percent reduction of Cr(VI) by ZVMg (5 g/L) was about 20 % after 60 min, but its complete reduction was attained within an hour when ultrasound was applied at a power of 100 W. The efficiency of Cr(VI) reduction increased with increasing ultrasonic power and magnesium dose. The synergy of the combined treatment has been attributed to the surface activation of ultrasonic treatment. Scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX), atomic absorption spectrophotometer (AAS), pH, and X-ray diffraction (XRD) analyses have revealed that magnesium and chromium hydroxides and hydroxide ion were three major by-products during the reduction of Cr(VI) by US/ZVMg under pH-uncontrolled conditions. The proposed method does not require acid and buffer addition and has an advantage of removing Cr(VI) and its by-product (Cr(III)) simultaneously.Öğe Ultrasound-assisted activation of zero-valent magnesium for nitrate denitrification: Identification of reaction by-products and pathways(Elsevier Science Bv, 2015) Ileri, Burcu; Ayyildiz, Onder; Apaydin, OmerZero-valent magnesium (Mg-0) was activated by ultrasound (US) in an aim to promote its potential use in water treatment without pH control. In this context, nitrate reduction was studied at batch conditions using various doses of magnesium powder and ultrasound power. While neither ultrasound nor zero-valent magnesium alone was effective for reducing nitrate in water, their combination removed up to 90% of 50 mg/L NO3-N within 60 min. The rate of nitrate reduction by US/Mg-0 enhanced with increasing ultrasonic power and magnesium dose. Nitrogen gas (N-2) and nitrite (NO2-) were detected as the major reduction by-products, while magnesium hydroxide Mg(OH)(2) and hydroxide ions (OH-) were identified as the main oxidation products. The results from SEM-EDS measurements revealed that the surface oxide level decreased significantly when the samples of Mg particles were exposed to ultrasonic treatment. The surface passivation of magnesium particles was successfully minimized by mechanical forces of ultrasound, which in turn paved the way to sustain the catalyst activity toward nitrate reduction. (C) 2015 Elsevier B.V. All rights reserved.
