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Öğe High-rate anaerobic treatment of digestate using fixed film reactors(Elsevier Sci Ltd, 2019) Ülgüdür, Nilüfer; Ergüder, Tuba H.; Demirer, Sibel Uludağ; Demirer, Göksel N.The effluent stream of the anaerobic digestion processes, the digestate, accommodates high residual organic content that needs to be further treated before discharge. Anaerobic treatment of digestate would not only reduce the residual organic compounds in digestate but also has a potential to capture the associated biogas. High-rate anaerobic reactor configurations can treat the waste streams using lower hydraulic retention times which requires less footprint opposed to the conventional completely stirred tank reactors. This study investigated the high-rate anaerobic treatment performance and the associated biogas capture from the digestate of a manure mixture composed of 90% laying hen and 10% cattle manures in fixed-film reactors. The results indicated that it was possible to reduce total chemical oxygen demand content of the digestate by 57-62% in 1.3-1.4 days of hydraulic retention time. The corresponding biogas yields obtained were in the range of 0.395-0.430 L-biogas/gVS(added) which were found to be comparable to many raw feedstocks. Moreover, significant total phosphorus reduction (36-47%) and greenhouse gas capture (over 14.5-18.1 tCO(2)e/d per m(3) digestate) were also recorded in the anaerobic fixed-film reactors. (C) 2019 Elsevier Ltd. All rights reserved.Öğe Heavy metal pollution and health risk assessment of road dust on selected highways in Duzce, Turkey(Taylor & Francis Ltd, 2018) Taşpınar, Fatih; Bozkurt, ZehraIn this study, road dust samples from state roads D-100 and D-655 passing through the city of Duzce, Turkey were analyzed using ICP-MS to ascertain heavy metal pollution, and also to evaluate possible risks to human health. Some pollution indices such as enrichment factors (EFs), geo-accumulation index (I-geo) and integrated pollution index (IPI) were calculated to determine the pollution levels of metals. According to the mean EF values, Zn, Mo, and Pb exhibited significant enrichment, while enrichment of As, Cd, Sn, and Sb was very high. The I-geo values for Pb, Ba, Mo, Zn, Cu, Mn, and Cr indicated an extremely polluted environment whereas those for Sc, V, Fe, As, Cd, Sn, and Sb indicated moderate to strong pollution of the environment. The IPI values of Pb and Mo were also at extreme levels due to vehicle traffic related contamination along the roads. Analysis of the road dust matrix indicated the mixed effect of the fossil fuel combustion for residential heating and industrial activities within the studied area as well as traffic originated pollution. Cluster analysis revealed that sampling area has been influenced by mainly three pollution sources: (i) traffic and industrial activities, (ii) polluted soil due to accumulation, and (iii) fossil fuel combustion. According to human health risk assessment studies, a level lower than 1.0 has been determined to be a non-cancer health risk. However, a total hazard index level of 1.4 poses a significant non-cancer health risk for children. Fortunately, a total lifetime cancer risk value of 8.8x10(-8) was found, and this is considered safe.Öğe HEAVY METAL CONTAMINATION AND ECOLOGICAL RISK ASSESSMENT IN THE SEDIMENTS OF MELEN RIVER, DUZCE, TURKEY(Parlar Scientific Publications (P S P), 2017) Keskin, ŞerefSediment samples were collected from along the Melen River. Those sediments have been affected municipal and industrial discharges that generated in around Duzce City, Turkey. In this study, the Melen River sediment pollution parameters were investigated. All locations are moderately enriched for Cr, Zn, and Pb and significantly enriched for Cd, Ni, and As. Ecological risk for Cd above 80 (97.21) and As was 76.99, indicating that this heavy metals pose moderate, moderate/high risk to the local ecosystem. All of the samples fall in the polluted areas (PLI>) and the highest pollution load index (PLI) (11.36) value was observed at the DM14 site. According to PCA analysis, the pollution levels of heavy metals in DM1, DM2, and DM3 locations were relatively lower than other sample locations. Cu, Cr, As, and Ni contents falls between the TEL and PEL values, moreover Ni concentration exceed to both of the PEL and ERM values. Especially, according to high values of Eri, PCA, and SQG in between DM9 to DM15 locations, studied sediments have under the moderate toxicity risk for Ni, Cd, As, and Cu.Öğe Forecasting of daily natural gas consumption on regional basis in Turkey using various computational methods(Elsevier Science Sa, 2013) Taşpınar, Fatih; Celebi, Numan; Tutkun, NedimIt is widely accepted that natural gas is a clean energy source that can be used to meet energy demand for heating and industrial purpose among the fossil fuels and its usage remarkably increases in order to maintain a clean environment in many countries in the world. It is fact that this makes energy investment planning in a country or region highly important for suitable economic development as well as environmental aspect. Therefore, energy demand for various sectors should be estimated in the frame of short-term energy policy. For accurate estimation of short-term energy demand a limited number of computational methods are employed by using the 4 yearly measured natural gas consumption values. Among these methods, the ANN and time series are widely used for short-term estimation of natural gas consumption in Turkey's certain regions. In this study, multilayer perceptron the ANNs with time series approach is proposed to forecast short-term natural gas consumption. Meteorological data (moisture, atmospheric pressure, wind speed and ambient temperature) obtained from the regional gas distribution company and the local meteorology office in last 4 years to construct well-tuned algorithm. Although the number of data was small, the proposed algorithm works well to forecast the short-term natural gas consumption and produces encouraging and meaningful outcomes for future energy investment policy. (C) 2012 Elsevier B.V. All rights reserved.Öğe Electrochemical Reduction of X-ray Contrast Iohexol at Mixed Metal Oxide Electrodes: Process Optimization and By-product Identification(Springer International Publishing Ag, 2018) Türkay, Özge; Barışçı, Sibel; Ulusoy, Ebru; Dimoglo, AnatoliThe reduction of commonly used X-ray contrast iohexol (IOX) by the electrooxidation process is presented in this study. To begin with, the effect of anode material was examined, and different mixed metal oxide electrodes (MMOs) such as Ti/RuO2, Ti/Pt, Ti/IrO2-RuO2, Ti/IrO2-Ta2O5, Ti/Ta2O5-SnO2-IrO2, and Pt/SnO2 were used. To assess experimental conditions at Ti/RuO2 anode, provided the highest removal efficiency, the response surface method was applied and the key influencing parameter was the process time. The determined optimal conditions were triplicated with real wastewater samples, and the average degradation efficiency of IOX was found to be 99%. By-products of the IOX degradation on the Ti/RuO2 anode have been identified using density functional theory and LC/MS-MS analysis. The results showed that IOX degradation opened with OH group detachment and resulted in the formation of a by-product with a molecular mass of 804 g mol(-1). Further degradation mechanism took place due to the breakup of C-4-C-10 and C-5-I-7 bonds with a by-product formed as 603 g mol(-1). Iodide atom replacement by OH groups caused the formation of a molecular fragment with 375 g mol(-1) molecular weight. The further disintegration of C-2-C-11 and C-6-N-16 sigma- bonds led to the formation of molecular masses of 133, 126, and 119 g mol(-1), respectively.Öğe Electrocoagulation/electroflotation as a combined process for the laundry wastewater purification and reuse(Elsevier, 2019) Dimoglo, Anatoli; Elibol, P. Sevim; Dinç, Özge; Gökmen, K.; Erdoğan, H.( )The purpose of this work is to purify wastewater from industrial laundries and return them to the washing process. By means of the methods of electrocoagulation and electroflotation, laboratory and pilot studies on the wastewater treatment were carried out using aluminium electrodes. The process of wastewater treatment has been studied in dependence on treatment time, temperature, pH and current density. The effectiveness of the cleaning process under different values of operating parameters of the reactor was estimated as the percentage of color, turbidity and surfactant removal from the wastewater. As a result of laboratory studies, the optimum values of the operating parameters of the reactor at 90% removal of contamination were the following: current density value as 5.26 mA/cm(2), pH as 5.5 and 5 min processing time. The consumption of electrical energy in this case amounted to 1.25 kWh/ m(3). The quality control of the purified water was carried out according to such additional parameters as total suspended solids, chemical oxygen demand, total organic carbon, and the content of metal ions and phosphate and nitrate anions in the water. The study of the wastewater treatment in a pilot plant with laboratory values of operating parameters showed the reproducibility of the purification results for the controlled parameters of water quality and suitability of the water for reuse. The washing performed with purified water was estimated by the whiteness index for bed linen and was not inferior to the traditional washing with water from a source of water supply.Öğe Effect of disinfection processes and anthropogenic pollutants on comparative formation of trihalomethanes and N-nitrosodimethylamine(Springer, 2019) Orak, Nur Hanife; Özşentürk, Tuğba; Topuz, Emel; Aydın, Egemen; Gürel, Melike; Genceli, Naciye Esra; Mantaş, Elif PehlivanoğluChloramination and chlorination contribute to the formation of N-nitrosodimethylamine and trihalomethanes, respectively, both of which are defined as disinfection by-products. To be able to select the most appropriate water treatment scheme, it is important to comparatively evaluate the formation of both of these disinfection by-products during the application of different disinfection methods. In this study, chlorination, chloramination and stepwise chloramination methods have been applied to surface water samples that have been spiked with known N-nitrosodimethylamine precursors. Experimental results showed that ranitidine can be an effective N-nitrosodimethylamine precursor in distilled water, when chloraminated with high concentrations (140mg/L) for a long time (10days), resulting in approximately 450ng/L of N-nitrosodimethylamine. However, neither dimethylamine nor ranitidine leads to significant trihalomethanes or N-nitrosodimethylamine formation in lake water when chloramination is conducted with low concentration (2mg/L) for 2h. These results suggest that N-nitrosodimethylamine concentration measured in the effluent of the drinking water treatment plant may underestimate the N-nitrosodimethylamine concentration that will reach the consumers since chloramination reactions will continue in the distribution system. On the other hand, when only N-nitrosodimethylamine formation potential is used, it will overestimate the N-nitrosodimethylamine that might form in the distribution system due to high disinfectant concentration, high contact time and adjusted pH values used in the N-nitrosodimethylamine formation potential test.Öğe Determination of the personal, indoor and outdoor exposure levels of inorganic gaseous pollutants in different microenvironments in an industrial city(Springer, 2015) Bozkurt, Zehra; Doğan, Güray; Arslanbaş, Demet; Pekey, Beyhan; Pekey, Hakan; Dumanoğlu, Yetkin; Tuncel, GürdalWe measured SO2, NO2 and O-3 concentrations during the summer and winter in Kocaeli, Turkey. The sampling was carried out indoors and outdoors at homes, schools and offices. Personal samplers were also used to determine personal exposures to these pollutants. High NO2 and SO2 concentrations were observed in outdoor samples collected close to locations characterized by heavy urban traffic. Concentrations of O-3, on the other hand, were higher in rural areas around the city due to ozone distillation. For both sampling periods, the concentrations of outdoor SO2 and O-3 were higher than for indoor and personal samples; however, the NO2 concentrations were higher in indoor and personal samples, indicating that outdoor sources significantly contribute to indoor SO2 and O-3 levels and that indoor NO2 concentrations are primarily modulated by sources within buildings. Seasonal variations in pollutant concentrations showed statistically significant differences. Indoor and outdoor concentrations of NO2 and SO2 measured in the winter were higher than the levels measured in the summer; O-3 concentrations, on the other hand, exhibited the opposite trend. Active-to-passive concentration ratios for NO2, SO2 and O-3 were 0.99, 1.08 and 1.16, respectively; the corresponding outdoor ratios were 0.95, 0.99 and 1.00.Öğe Determination of airborne trace elements in an urban area using lichens as biomonitor(Springer, 2017) Bozkurt, ZehraThe amounts of elements emitted from industrial, domestic, and vehicle sources in Duce through the analyses of lichens, which are bioindicators of air pollution, were determined in this research. Concentrations of Al, Fe, Cr, Mn, Co, Ni, Cu, Zn, As, V, Cd, Hg, and Pb in the lichens that were collected from 40 different points were analyzed using an inductively coupled plasma (ICP-MS) device. The highest concentration values were detected for Fe and Al, while the lowest concentration values were detected for Cd and Hg. Distribution maps of elements were created using geographic information systems. The distribution maps showed how the concentrations of elements for Duzce have changed across the city. According to our results, the elements sourced from traffic and combustion, such as Cr, Co, Ni, Cu, As, and V, have the highest concentrations in the city center near the traffic.Öğe Depositional environment characteristics of UlukA +/- AYla Evaporites, Central Anatolia, Turkey(Springer, 2017) Keskin, Şeref; Şener, Mehmet; Şener, Mehmet Furkan; Öztürk, Muhammed ZeynelThis paper examines evaporated deposits of gypsum known as the UlukA +/- AYla Evaporites located in the UlukA +/- AYla Basin, central Anatolia, Turkey. The Late Eocene compression between the Eurasian and Afro-Arabian plates formed numerous shallow epicontinental basins in SE central Anatolia. During this period, the UlukA +/- AYla Basin was a shallow marine environment. The composition of the UlukA +/- AYla Basin indicates that gypsum and stromatolite were deposited due to an arid climate and sea level oscillation between 37.25 and 38.52 Ma. Oxygen, sulfur, and strontium isotopes and the geochemistry of the evaporated rocks were measured to understand the paleoenvironment of this formation. Trace element analyses of Fe, K, Mg, Na, Mn, Sr, Ni, and Cu from the gypsum samples showed very high variability. The average K/Na, Sr/Ca, and Mg/Na were measured to be 0.4, 2.35, and 2.9 %, respectively, which indicates that the UlukA +/- AYla gypsum lies in a formerly hypersaline environment. Sr-87/Sr-86, O-18, and S-34 isotope ratios indicate that the gypsum was deposited in marine water then mixed with fresh continental water.Öğe Time Series Models for Air Pollution Modelling Considering the Shift to Natural Gas in a Turkish City(Wiley, 2015) Taşpınar, FatihFossil fuel utilization for residential heating is still a major source of fine particulate matter (PM10) and sulphur dioxide (SO2), despite the increasing consumption of natural gas in some cities in Turkey. In the present study, PM10 and SO2 air pollution and residential natural gas consumption (RNGC) were modelled by various multi-parameter time series modelling methods (TSMs). To estimate short-term pollution levels considering the future estimates of RNGC and meteorological factors, a time series dataset was designed for the years 2007-2013. Factor analysis was also performed to aid in the selection of variables for constructing TSMs. The error measures and coefficient of determination (R-2) were used to evaluate forecasting accuracy of the models constructed. In the short-term estimation of RNGC, PM10, and SO2 for 2014-2015, temperature dependent ARIMAX(1,1,2) (R-2 = 0.944) and RNGC and meteorological factors dependent SARIMAX(0,1,1)(1,1,0) 12 (R-2 = 0.761) and ARIMAX(1,1,0) (R-2 = 0.698) models, respectively, yielded the best fitting scores and accuracy measures. The models performed well in reflecting the time series data and thus, could be utilized in energy planning for sustainable development concerning environmental decision making and short-term air quality forecasting for public health.Öğe Source Identification of Volatile Organic Compounds and Particulate Matters in an Urban and Industrial Areas of Turkey(Foundation Environmental Protection & Research-Fepr, 2015) Pekey, Hakan; Pekey, Beyhan; Arslanbaş, Demet; Bozkurt, Zehra; Doğan, Güray; Tuncel, GürdalElevated levels of volatile organic compounds (VOCs) and particulate matters have been observed in recent years in Kocaeli, Turkey, despite improvements in pollution prevention technology that have led to a reduction in gas and particulate emissions. Local authorities should devise alternative strategies to reduce the possible health effects of a variety of pollutants that affect air quality. The objective of this study was to identify potential sources of VOCs, fine particulate matter (PM2.5) and coarse particulate matter (PM10) concentrations in atmospheric aerosols that were collected in the highly industrialised area of Kocaeli, Turkey, during the winter and summer months by using wind directions. Samples were collected from May 2006 to January 2007, and concentrations of eight elements (As, Cr, Cu, Mn, Ni, Pb, V and Zn) were measured using energy dispersive X-ray fluorescence (EDXRF) and wavelength dispersive X-ray fluorescence (WDXRF) spectrometer. Samples were analysed for thirteen VOCs, including benzene, toluene, m/p-xylene, o-xylene, ethylbenzene, styrene, cyclohexane, 1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene, hexane, nonane and dodecane using thermal desorption (TD) and a gas chromatography/flame ionisation detector (GC/FID). The results show that vehicular emissions, oil and coal combustions, petroleum refinery and hazardous and medical waste incinerator are the significant sources of VOCs, PM2.5 and PM10 concentrations in Kocaeli.Öğe Simultaneous dissolution and uptake of nutrients in microalgal treatment of the secondarily treated digestate(Elsevier, 2019) Ülgüdür, Nilüfer; Ergüder, Tuba H.; Demirer, Göksel N.Anaerobic digestion processes result in large volumes of digestates which still require the development of elaborate and viable management options to improve the sustainability of these processes. Coupling of secondary anaerobic treatment with a microalgal nutrient removal process may serve benefits such as residual biogas and associated greenhouse gas capture from the digestate content, microalgal biomass build-up and its further valorization. This study investigated the applicability a microalgal nutrient removal process in a secondarily treated digestate (the digestate of a digestate) as a complementary unit. The results indicated that up to 100% dissolved reactive phosphorus (DRP), 97.8% total dissolved phosphorus (TDP) and 93.7% ammonium nitrogen (NH4+-N) removal could be attained in the treatment of the digestate of a digestate using microalgal cultures. Folding phosphorus concentrations via dissolution was found to compensate for dilution related phosphorus deficiency for microalgal growth. Microalgal biomass obtained by the end of operation could be concentrated from 6.4-15.5 mg/L to 164.2-502.6 mg/L (2100-7900%) by simple gravity settling which was correlated with the prevalence of agglomerated particles in the size range of 10-100 mu m. The results demonstrated not only the applicability of the microalgal process after secondary anaerobic treatment of the digestate, but also brought about the dissolution concept for nutrients during microalgal growth.Öğe Seasonal variation of water-soluble inorganic ions in PM10 in a city of northwestern Turkey(Taylor & Francis Ltd, 2018) Bozkurt, ZehraThe objective of this study was to determine the concentrations of inorganic ions present in particulate matter smaller than 10 mm (PM10), released into the environment by industrial, domestic and mobile sources in Duzce. To assess spatial variations, samples were collected from two sampling sites that had urban and suburban characteristics. Further, the process was carried out in two seasons to understand the seasonal variations. An ion chromatography device was used for analyzing the inorganic ion content in the collected samples. The highest levels of inorganic ion concentrations were measured at the urban sampling site during the winter campaign. Furthermore, the highest ion concentrations were measured for SO42- ion at both sampling sites and during both seasons, while the lowest concentrations were measured for Br-. Moreover, there were significant relationships between meteorological parameters and ion concentrations. A comparison of the cation and anion equivalence values using seasonal CE/AE (cation equivalence/anion equivalence) ratios showed that the aerosol matter had alkaline characteristics during both seasons. The mean value for the CE/AE ratios was 1.58 in winter and 2.06 in summer at the urban sampling site and 1.36 in winter and 1.52 in summer at the suburban sampling site. The interrelationships among the ions were determined by Pearson correlation analysis. Based on the correlation analyses, the ions emitted from common sources and those exposed to similar atmospheric conditions displayed strong correlations with each other.Öğe QUALITY ASSESSMENT AND CHEMICAL COMPOSITION OF SURFACE WATER IN THE AKCADAG BASIN (MALATYA), TURKEY: A CASE STUDY FOR IRRIGATION AND DRINKING PURPOSES(Parlar Scientific Publications (P S P), 2019) Şahin, Serap Koşal; Sivri, Nüket; Şahin, Ülkü Alver; Sönmez, Vildan Zülal; Şeker, Dursun ZaferThe quality of irrigation water has a considerable impact on what plants can be successfully grown, the productivity of these plants, and water infiltration and other soil physical conditions. Irrigated agriculture is dependent on an adequate water supply of usable quality. To avoid problems when using poor quality water supplies, there must be sound planning to ensure that the quality of water available is put to the best use. The usage of irrigation water by Polat and Silrgti Streams is one of the most important factors in respect to the intensification of agricultural activities in the Akcadag Basin. Responsible and accurate use of these factors by means of GIS is of vital importance. This study aims to visualize waters defined to be qualified to be used for irrigation or drinking purposes with the aid of GIS and to ensure the sustainable use of surface waters in the Akcadag Basin. The most common measure to assess irrigation in water is called the Sodium Adsorption Ratio (SAR). The SAR defines sodicity in terms of the relative concentration of sodium (Na) compared to the sum of calcium (Ca) and magnesium (Mg) ions in a sample. The SAR assesses the potential for infiltration problems due to a sodium imbalance in irrigation water. The highest value was found in SAR station 2 (0.473) while the lowest value (0.027) was calculated in the station 7. The selected stations should be monitored in wet and dry seasons in order to provide a more accurate interpretation of the area and to ensure proper use. It is possible to aim to protect water resources and make people reach these resources in a healthy way, to create a sustainable water management policy by means of different monitoring tools to be used for the monitoring of the area.Öğe Partial purification and characterization of the novel halotolerant and alkalophilic laccase produced by a new isolate of Bacillus subtilis LP2(Taylor & Francis Ltd, 2019) Yaşar, Gülhan; Guven, Ünzile Gülhan; Güdük, Elif; Aktaş, FatihLaccases (benzenediol: oxygen oxidoreductases, [EC1.10.3.2] are mostly known as members of the blue multicopper oxidase family that are used in very different industrial applications: textile, pulp and paper, food, cosmetics industries, bioremediation process, biosensor, biofuel and organic synthesis. Stability against the extreme conditions is an important property and it makes laccase suitable for several industrial processes. Laccase should have salt resistance to be used in textile dye degradation because the textile wastewaters include dyes with high concentrations of salts, especially NaCl. Bacterial laccases are preferable to be used for bioremediation process due to their high stability to extremely salt contaminated and alkalophilic environment. Bacillus subtilis LP2 was identified as a source of alkali-tolerant, salt resistant laccase. Laccase showed activity over a wide pH (4-10) and temperature (30-80 degrees C) range. Maximum laccase activity was observed as 140.4U/mg (umol/min*mg) at pH 8 and 50 degrees C with the substrate guaiacol. Stability of laccase was determined as 60% and 20% after incubation of the enzyme for different time intervals of 20 and 40min at 50 degrees C and pH 8. SDS (10mM) and EDTA (5mM) decreased laccase activity from 100% to 0% and 56%, respectively. Despite the other inhibitors, NaCI increased the activity of laccase to 167% at 500mM concentration. Laccase from Bacillus subtilis LP2 barely showed the activity on the substrates vanillin and L-tyrosine. These results clearly show that laccase from Bacillus subtilis LP2 has high potential to be used for several applications in textile industry.Öğe In vitro biocompatibility study approaches to evaluate the safety profile of electrolyzed water for skin and eye(Sage Publications Ltd, 2019) Sipahi, Hande; Reis, Rengin; Dinç, Özge; Kavaz, T.; Dimoglo, Anatoli; Aydın, AhmetElectrolyzed water (EW) is a widely used disinfectant agent with high oxidation-reduction potential (ORP). Although EW has been used in many areas, such as food hygiene, agriculture, and animal husbandry, the studies presented in the literature are not enough to clarify the toxic effects of EW. The aim of this study is, therefore, to produce EWs at different pH, ORP, and chlorine concentrations and to assess their safety in terms of toxicology. At the beginning of the study, the antimicrobial activity of the EW types with respect to bacteria and fungus was investigated. EWs below pH 7 were all effective in inactivating Enterococcus hirae, Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans completely. In vitro studies of cell cultures revealed that different concentrations of EWs were not cytotoxic for the L929 cells under 10- to 80-fold dilutions. In addition, it has been determined that produced EWs did not have irritation potential, according to the in vitro EpiDerm((TM)), reconstituted skin irritation test in the frames of biocompatibility tests. For the mucous membrane irritation test, the hen's egg test-chorioallantoic membrane experiment was performed, and EWs were found to have no eye irritation. In conclusion, it has been shown that produced EWs with antimicrobial efficacy were found to be safe for skin and eye according to in vitro biocompatibility study studies. Thus, the establishment of a technological infrastructure for the EW production and the use of produced EW as an effective disinfectant in the food, medical, and agricultural areas should be encouraged.Öğe Improving artificial neural network model predictions of daily average PM10 concentrations by applying principle component analysis and implementing seasonal models(Taylor & Francis Inc, 2015) Taşpınar, FatihThis study introduces a seasonal modeling approach in the prediction of daily average PM10 (particulate matter with an aerodynamic diameter <10 m) levels 1 day ahead based on multilayer perceptron artificial neural network (MLP-ANN) forecasters. The data set covered all daily based meteorological parameters and PM10 concentrations in the period of 2007-2014. Seasonal ANN models for winter and summer periods were separately developed and trained by using a lagged time series data set. The most significant lagged terms of the variables within a 1-week period were determined by principal component analysis (PCA) and assigned as input vectors of ANN models. Cascading training with error back-propagation method was applied in model building. The use of seasonal ANN models with PCA-based inputs showed an increased prediction performance compared with nonseasonal models. For seasonal ANN models, the overall model agreement in training between modeled and observed values varied in the range of 0.78-0.83 and R-2 values ranged in 0.681-0.727, which outperformed nonseasonal models. The best testing R-2 values of seasonal models for winter and summer periods ranged in 0.709-0.727 with lower testing error, and the models did not show a tendency towards overpredicting or underpredicting the PM10 levels. The approach demonstrated in the study appeared to be promising for predicting short-term levels of pollutants through the data sets with high irregularities and could have significant applicability in the case of large number of considered inputs.Implications: This study provides an alternative approach to predict PM10 levels 1 day ahead by building seasonal ANN models. Applying PCA on a lagged data set resulted in selection of the most significant lags of variables reducing model complexity. Cascading training with error back-propagation method appropriately determined hidden layer neurons. Separately building ANN models for winter and summer periods over years, even though it required much more effort compared with building regular nonseasonal models, yielded better model agreements and smaller testing errors. This approach can be applied on the data sets with irregularities and a large number of considered inputs.Öğe Comparative evaluation of disinfection mechanism of sodium hypochlorite, chlorine dioxide and electroactivated water on Enterococcus faecalis(Elsevier Science Bv, 2019) Ersoy, Zeynep Girgin; Dinç, Özge; Çınar, Buse; Gedik, Sedef Tunca; Dimoglo, AnatoliThe aim of this study is to compare the efficiency of chlorine-based disinfectants, namely, sodium hypochlorite (NaOCl), chlorine dioxide (ClO2), and electroactivated water (EAW), and to investigate their inactivation mechanisms on a Gram positive, opportunistic pathogen Enterococcus faecalis. Cell viability, damages on membrane integrity and cellular components were examined to reveal underlying mechanisms of the disinfection process. Among three disinfectants, EAW was the most effective one to inactivate E. faecalis in less time with more damage. According to flow cytometry results, EAW destroyed 95.4% of bacteria within 1 min whereas NaOCl and ClO2 provided 73.9% and 72.6% bacterial inactivation after 20 min of treatment. The rapid increment at conductivity and lipid peroxidation within 30 s of treatment indicates that EAW causes membrane damage much more expeditiously compared to other disinfectants. DNA and protein leakage increased gradually during the treatment with EAW and reached 44.9 and 5.8 mu g/ml, respectively. All disinfectants were found as inactivating the bacteria by disrupting cell membrane integrity, unbalancing the ion concentration and damaging the cellular components such as DNA, protein, lipid molecules. It is considered that EAW is more effective due to its superior content including chlorine dioxide, free radicals and ozone besides hypochlorous acid.Öğe Characterization and source estimates of primary and secondary carbonaceous aerosols at urban and suburban atmospheres of Duzce, Turkey(Springer Heidelberg, 2019) Kılavuz, Seda Aslan; Bozkurt, Zehra; Öztürk, FatmaDuzce is one of the cities located in the western Black Sea region of Turkey with a population of 377,610 in 2017 (TUIK, 2017). There is no satisfying scientific information available to address the contribution of primary and secondary sources of carbonaceous aerosols to the observed PM10 levels in the city. The main objective of the study is to determine the levels and sources of carbonaceous aerosols in PM10. For this purpose, PM10 samples were collected at urban and suburban locations in Duzce during winter and summer season in 2015. Average summer OC and EC concentrations in the urban area were 9.5 and 1.3gm(-3), respectively, while the corresponding concentrations were observed as 28.5 and 2.3gm(-3), respectively for winter season. Summer mean OC and EC levels at the suburban site were 5.46 and 0.37gm(-3), respectively, while those for winter were found as 6.68 and 0.61gm(-3).The contributions of OC and EC to measured PM10 levels were found in the range of 10% to 60% and 1% to 7%, respectively, at the urban station while the associated contributions were in the range of 10% to 50% and 0.6% to 6%, respectively, at the suburban station. The concentrations measured during winter months in both areas were found to be higher than those measured during summer months. The EC tracer method was used in order to estimate the SOC contribution. The contribution of SOC concentrations to the total PM10 mass was found to be higher during winter in the urban area and during summer in the suburban area.
