Mehmet Salim Öncel
Gebze Institute of Technology
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Featured researches published by Mehmet Salim Öncel.
Desalination and Water Treatment | 2013
M. Kobya; E. Demirbas; U. Gebologlu; Mehmet Salim Öncel; Yilmaz Yildirim
AbstractIn this investigation, arsenic removal from drinking water using electrocoagulation (EC) in a batch mode was studied by response surface methodology (RSM). The RSM was applied to optimize the operating variables viz. current density (CD, A/m2), operating time (tEC, min) and arsenic concentration (Co, μg/L) on arsenic removal in the EC process using iron electrodes. The combined effects of these variables were analyzed by the RSM using quadratic model for predicting the highest removal efficiency of arsenic from drinking water. The proposed model fitted very well with the experimental data. R2 adjusted correlation coefficients (AdjR2: 0.93) for arsenic removal efficiency showed a high significance of the model. The model predicted for a maximum removal of arsenic at the optimum operating conditions (112.3 μg/L, 5.64 A/m2 and 5 min) after the EC process was 93.86% which corresponded to effluent arsenic concentration of 6.9 μg/L. The minimum operating cost (OC) of the EC process was 0.0664 €/m3. This...
Chemosphere | 2018
Philip Isaac Omwene; Mehmet Salim Öncel; Meltem Çelen; M. Kobya
Mining activities in addition to the geology of Mustafakemalpaşa catchment have for long been linked to its deteriorating water and sediment quality. This study assessed contamination levels of heavy metals and other major elements (Pb, As, B, Cd, Zn, Cr, Mo, Co, Ni, Cu, and Ag) in surface sediments of the area, and identified possible pollution sources. Sediment quality indicators, such as contamination factor (CF), enrichment factor (EF), geo-accumulation index (Igeo) and sediment quality guidelines were used, in addition to multivariate statistical technics; Pearson Correlation Matrix (PCM), Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA). The highest contamination (annual average > 110 mg kg-1) was revealed by B, Cr, Ni, Zn and As. Moreover, As, Cd and Ni levels exceeded their respective probable effect concentrations (PEC), posing a potential negative impact to biota. The highest Igeo values were recorded for Cr, B, Ni, As and Zn, and occurred near urban settlements and mining sites, particularly of coal and chromium. The present study also suggests use of site rank index (SRI) as an alternative to pollution load index (PLI), since the former is derived from the data of interest and eliminates arbitrary classifications. The sources of heavy metals in the sediments were attributed to fly ashes of coal-powered plants, urban waste leachate and weathering of sulfide ore minerals for Pb, Zn and Cu; urban-industrial wastes and mining wastes for Ni. Although Cr, As, Cd and B were ascribed to natural occurrence, their presences in river sediment is accelerated by mining.
The Open Waste Management Journal | 2018
Senem Bayar; Nihal Bektaş; Mehmet Salim Öncel; Guleda Onkal Engin; Yasemin Ç; Emin Ender Çelebi
RESEARCH ARTICLE Hazardous Wastes and Waste Generation Factors Originating from Battery and Accumulator Manufacturing Sector in Turkey Senem Bayar, Nihal Bektaş, Mehmet S. Öncel, Güleda O. Engin, Yasemin Ç and Emin E. Çelebi Department of Environmental Engineering, Gebze Tecnical University, 41400, Gebze, Kocaeli, Turkey Department of Environmental Engineering, Yildiz Tecnical University, Esenler, Istanbul, Turkey
Water Science and Technology | 2017
Emin Ender Çelebi; Mehmet Salim Öncel; M. Kobya
Weathering of sulfide minerals is a principal source of acid generation. To determine acid-forming potentials of sulfide-bearing materials, two basic approaches named static and kinetic tests are available. Static tests are short-term, and easily undertaken within a few days and in a laboratory. In contrast, kinetic tests are long-term procedures and mostly carried out on site. In this study, experiments were conducted over a medium-term period of 2 months, not as short as static tests and also not as long as kinetic tests. As a result, pH and electrical conductivity oscillations as a function of time, acid-forming potentials and elemental contents of synthetically prepared rainwater leachates of massive sulfides and sulfide-bearing lead-zinc tailings from abandoned and currently used deposition areas have been determined. Although the lowest final pH of 2.70 was obtained in massive pyrite leachate, massive chalcopyrite leachate showed the highest titrable acidity of 1.764 g H2SO4/L. On the other hand, a composite of currently deposited mine tailings showed no acidic characteristic with a final pH of 7.77. The composite abandoned mine tailing leachate had a final pH of 6.70, close to the final pH of massive galena and sphalerite leachates, and produced a slight titrable acidity of 0.130 g H2SO4/L.
Turkish Journal of Biology | 2016
Tuğrul Doruk; Zeynep Girgin Ersoy; Mehmet Salim Öncel; Sedef Tunca Gedik
Inorganic phosphate is stored as a polyphosphate (polyP) polymer inside every living cell. This polymer is synthesized by the polyP kinase (PPK) enzyme using the terminal phosphate of ATP as substrate and it performs important functions in the cell. In this study, effects of high levels of PPK on Bacillus thuringiensis subsp. israelensis were analyzed. Recombinant Bti ppk, a PPK overproducer, was found to uptake more phosphate into the cell and produce a consistently higher amount of endotoxin than the wild type under culture conditions including a range of temperatures (25 °C, 30 °C, and 37 °C), pH values (pH 5, 6, 8, and 9), and carbon sources (maltose, mannitol, sucrose, and starch). Moreover, this strain was found to overexpress sigB, which might cause a significant increase in the acid tolerance of this microorganism. Spores of Bti ppk were found to be smaller compared to wild-type spores; however, bioassay experiments with third-instar wild Culex pipiens larvae proved that high toxicity is not the result of small spore size. This hypertoxic recombinant Bti strain is very useful for industrial applications, not only because it produces more endotoxin than the wild type under different culture conditions, but also because it is more acid-tolerant under the conditions tested.
International Journal of Green Energy | 2016
Guleda Onkal Engin; Nilufer Ömürlü; Mehmet Salim Öncel
ABSTRACT Increase in waste sludge disposal is always seen as a problem from the point of production industry. However, it is clear that the reuse and recycle of sewage sludge could be a serious economic input. The most important action should be to determine the sludge characterizations and direct the producers towards appropriate reuse and recycling opportunities. In this study, reuse method was examined to produce coal briquette, which will constitute an example for waste sludge. In order to make use of the waste sludge, five different coal briquette samples were produced by mixing powdered coal and bitumen together with waste sludge, at different ratios. The overall results indicated that the sample named CB3 having 70% powdered coal, 20% waste sludge, and 10% bitumen was found to be the optimum coal briquette among the other samples produced. The proximate analysis of the optimum briquette sample was carried out according to the Turkish standards and regulations and it was found out that the produced briquette coal can have commercial value with a gross calorific value of 30.03 MJ/kg and 7.30% ash content.
Separation and Purification Technology | 2011
M. Kobya; Feride Ulu; Ugur Gebologlu; E. Demirbas; Mehmet Salim Öncel
Journal of environmental chemical engineering | 2013
Mehmet Salim Öncel; A. Muhcu; E. Demirbas; M. Kobya
Environmental Progress | 2014
M. Kobya; Abdurrahman Akyol; E. Demirbas; Mehmet Salim Öncel
Journal of environmental chemical engineering | 2015
M. Kobya; F. Ozyonar; E. Demirbas; E. Sık; Mehmet Salim Öncel