Person: ÇALLI, BARIŞ
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ÇALLI
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BARIŞ
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Publication Metadata only Prediction of future disposal of end-of-life refrigerators containing CFC-11(PERGAMON-ELSEVIER SCIENCE LTD, 2014) ÇALLI, BARIŞ; Yazici, Burcu; Can, Zehra S.; Calli, BansThe objective of this study was to predict the number of refrigerators containing CFC-11 blown isolation foam and the amount of CFC-11 banked in these refrigerators. By using a Weibull-based survival function, the number of CFC-11 containing and still-functioning refrigerators was estimated to be approximately 1.6 million in 2013 in Turkey. In order to determine the amount of CFC-11 in the isolation foam of these refrigerators, polyurethane (PU) foam samples were taken from a refrigerator manufactured in 1993 and the quantity of CFC-11 was analyzed by a GC-MS. It was determined that 113-195 mg CFC-11/g PU remains in the PU foam depending on the location such as door, sides, top and bottom. Knowing that a mid-sized refrigerator contains 4 kg PU on average, the total amount of PU foam to be disposed of is 6344 tons when the CFC-11 containing refrigerators in Turkey become obsolete in the near future. Furthermore, 717-1237 tons of CFC-11 are expected to be banked in the PU foam of these refrigerators which will exert an equivalent amount of ozone depleting potential (ODP). In addition, the global warming potential will vary between 3.4 and 5.9 million tons of CO2. (C) 2013 Elsevier Ltd. All rights reserved.Publication Metadata only Influence of trace element supplementation on anaerobic digestion of chicken manure: Linking process stability to methanogenic population dynamics(ELSEVIER SCI LTD, 2018) ÇALLI, BARIŞ; Molaey, Rahim; Bayrakdar, Alper; Surmeli, Recep Onder; Calli, BarisThe effect of trace elements supplementation in anaerobic digestion of chicken manure (CM) and their influence on methanogenic population dynamics were assessed at total ammonia nitrogen (TAN) concentrations as high as 5000?mg/L for 332 days. With addition of selenium (Se), the CH4 yield increased 50% and reached to 0.27?+/-?0.01?L/g of volatile solids (VS) added. The results of metagenomic analysis showed that Se supplementation improved the digestion stability and CH4 production by increasing the activity and number of hydrogenotrophic Methanoculleus bourgensis. Due to the deficiency of trace elements other than Se, in course of time the CH4 yield decreased and dropped to 0.13?L/g of VS added. After starting to add a trace element mix containing cobalt (Co), nickel (Ni), molybdenum (Mo), tungsten (W) and Se, another hydrogenotrophic methanogen, Methanobrevibacter became dominant in the digester. Accordingly, along with the conversion of propionate to acetate and consumption of acetate via syntrophic acetate oxidation, the CH4 yield increased and reached to steady state at 0.32 +/- 0.01 L/g of VS added. (C) 2018 Elsevier Ltd. All rights reserved.Publication Metadata only Monitoring of population shifts in an enriched nitrifying system under gradually increased cadmium loading(ELSEVIER SCIENCE BV, 2008) ÇALLI, BARIŞ; Mertoglu, Bulent; Semerci, Neslihan; Guler, Nuray; Calli, Baris; Cecen, Ferhan; Saatc, Ahmet MeteThe changes in nitrifying bacterial population under cadmium loading were monitored and evaluated in a laboratory scale continuous-flow enriched nitrification system. For this purpose, the following molecular microbiological methods were used: slot-blot hybridization, denaturing gradient gel electrophoresis (DGGE), real-time PCR followed by melting curve analysis, cloning and sequence analysis. The initial cadmium concentration was incrementally increased from 1 to 10mg/l which led to a drop in ammonia removal efficiency from 99 to 10%. inhibition was recovered when cadmium loading was stopped. During the second application of cadmium. nitrifying population became more tolerant. Even at 15 mg/l Cd, only a minor inhibition was observed. To investigate the variations in ammonia and nitrite oxidizing bacteria populations in a period of 483 days, ammonia monooxygenase (amoA) and 16S rRNA genes-based molecular techniques were used. An obvious shift was experienced in the diversity of ammonia oxidizers after the first application of 10mg/l Cd. Metal-tolerant ammonia oxidizing species became dominant and the microbial diversity sharply shifted from Nitrosomonas and Nitrosococcus sp. to Nitrosospira sp. which were observed to tolerate higher cadmium loadings. This result indicated that the extent of nitrification inhibition was not only related to the metal concentration and quantity of microorganisms but also depended on the type of species. (C) 2008 Elsevier B.V. All rights reserved.Publication Metadata only Biogas desulfurization using autotrophic denitrification process(SPRINGER, 2016) ÇALLI, BARIŞ; Bayrakdar, Alper; Tilahun, Ebrahim; Calli, BarisThe aim of this study was to evaluate the performance of an autotrophic denitrification process for desulfurization of biogas produced from a chicken manure digester. A laboratory scale upflow fixed bed reactor (UFBR) was operated for 105 days and fed with sodium sulfide or H2S scrubbed from the biogas and nitrate as electron donor and acceptor, respectively. The S/N ratio (2.5 mol/mol) of the feed solution was kept constant throughout the study. When the UFBR was fed with sodium sulfide solution with an influent pH of 7.7, about 95 % sulfide and 90 % nitrate removal efficiencies were achieved. However, the inlet of the UFBR was clogged several times due to the accumulation of biologically produced elemental sulfur particles and the clogging resulted in operational problems. When the UFBR was fed with the H2S absorbed from the biogas and operated with an influent pH of 8-9, around 98 % sulfide and 97 % nitrate removal efficiencies were obtained. In this way, above 95 % of the H2S in the biogas was removed as elemental sulfur and the reactor effluent was reused as scrubbing liquid without any clogging problem.Publication Metadata only Anaerobic digestion of chicken manure by a leach-bed process coupled with side-stream membrane ammonia separation(ELSEVIER SCI LTD, 2018) ÇALLI, BARIŞ; Bayrakdar, Alper; Surmeli, Recep Onder; Calli, BarisThis study pioneered the use of a single-stage methanogenic leach bed reactor (LBR) for high-solids (total solid content: 14%-16%) anaerobic mono-digestion of chicken manure. Chicken manure was loaded into the LBR in cloth sachets without adding any bulking agents. Ammonia was separated and recovered by placing a hydrophobic gas diffusion membrane in a leachate collection chamber. Methane production in the membrane-integrated LBR was 0.272 m(3)/kgVS and 2.3 times higher than that in the control LBR. The results revealed that using membrane-integrated LBR for anaerobic digestion is a simple and cost-efficient technology for the monodigestion of chicken manure and ammonia removal.Publication Metadata only Dark fermentative H-2 production from xylose and lactose - Effects of on-line pH control(PERGAMON-ELSEVIER SCIENCE LTD, 2008) ÇALLI, BARIŞ; Calli, Baris; Schoenmaekers, Kim; Vanbroekhoven, Karolien; Diels, LudoAlthough xylose and lactose, two major carbohydrates existing in lignocellulosic and dairy wastes, are produced in huge amounts every year, their potentials in dark fermentative H-2 production were not investigated sufficiently and the optimum fermentation pH is still unclear particularly at thermophilic temperatures. Therefore, in this study, the influence of pH on fermentative H-2 production from xylose and lactose was investigated using a mixed culture compost inoculum. Completely mixed thermophilic (55 degrees C) bioreactors were operated in sequential batch mode at constant pH levels between 4.7 and 6.5. The highest H-2 yield in fermentation of xylose was achieved as 1.70 mol/mol at pH 5.0. The H-2 yield was strongly affected by the level of pH and butyrate fermentation. The unsatisfactory yields were associated with lactate fermentation at pH 4.7 and without pH control and with ethanol formation at pH 6.0. The optimal pH for stable H-2 yield from lactose was suggested to be 5.3 considering the molar yields increased to a maximum of 3.45 mol H-2/mol hexose sugar. Another indication of efficient H-2 production at pH 5.3 was the metabolic shift from ethanol to butyrate fermentation. Acetate fermentation yielding H-2 below stoichiometric ratios especially in low H-2 yielding runs revealed that some portion of the H-2 was consumed by acetogenic bacteria. (C) 2007 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.Publication Metadata only Simultaneous nitrate and sulfide removal using a bio-electrochemical system(ELSEVIER SCIENCE SA, 2019) ÇALLI, BARIŞ; Bayrakdar, Alper; Tilahun, Ebrahim; Calli, BarisThis study addresses the applicability of simultaneous nitrate and sulfide removal using two-chamber bioelectrochemical systems (BES). The anode and cathode chambers of a BES were fed with the effluent of a sulfate reducing reactor and a nitrate-rich groundwater as an electron donor and acceptor sources, respectively. BES has been found to be effective for simultaneous removal of sulfide and nitrate coming from different sources and without mixing them. As a result, 10 gS/m(3)/d of sulfide oxidation and 7.26 gN/m(3)/d of nitrate reduction rates were achieved. The number of electrons used for denitrification was more than that of delivered from the anode, especially when the anode chamber was fed with the SRR effluent and operated at pH 7-7.5. It was supposed that H2S was used for denitrification in the cathode by passing through the membrane. Another reason for this might be the electrons released from the corroding steel mesh current collector. (C) 2019 Elsevier B.V. All rights reserved.Publication Metadata only Effect of Operating Conditions on Separation of H2S from Biogas Using a Chemical Assisted PDMS Membrane Process(SPRINGER, 2018) ÇALLI, BARIŞ; Tilahun, Ebrahim; Sahinkaya, Erkan; Calli, BarisHydrogen sulfide (H2S) is an undesirable impurity that has to be removed from biogas to avoid the corrosion of co-generation units. In the present study, we evaluated the potential of a gas-liquid membrane contactor process for selective removal of H2S from biogas. The effects of biogas retention time (GRT), membrane thickness and liquid absorbent pH were investigated. A dilute sodium hydroxide solution was used as absorbent. The results revealed that H2S removal efficiency (RE) improved with increasing GRT and absorbent pH, and decreased with increasing membrane thickness. When GRT reduced from 19 to 3.4min, the RE of H2S and CO2 decreased by over 2.5 and 5.2 times, respectively. In contrast, a higher desulfurization selectivity was observed with lower GRT and thicker membranes. The CH4 content of the treated biogas increased along with increasing GRT and was enriched from 60% to a maximum of 87% with only 4.68% loss. The SEM-EDS analysis confirmed the deposition of inorganics such as Ca, Mg, S and Si on the membrane surface. However, any membrane clogging and fouling problem was not observed. In summary, the novel gas-liquid polydimethylsiloxane membrane contactor tested in this study has performed well in selective removal of H2S from biogas and is expected to be a promising alternative to conventional desulfurization processes.Publication Metadata only Ammonia and pH inhibition in anaerobic treatment of wastewaters, part II: Model development(TAYLOR & FRANCIS INC, 2004) ÇALLI, BARIŞ; Eldem, NO; Akgiray, O; Ozturk, I; Soyer, E; Calli, BA new model to account for the influences of pH and ammonia on methane production in the anaerobic treatment of wastewaters is presented. The model is developed and evaluated by using two different sets of experimental data obtained using seeds from two different full-scale industrial anaerobic reactors. One of the seeds was obtained from an expanded granular sludge-blanket (EGSB) reactor treating a corn processing waste. The other seed was obtained from an upflow anaerobic sludge-blanket reactor (UASB) treating waste from a potato chips production plant. Model development is based on the data collected at four different pH values (6.8, 7.4, 7.8, 8.4) and with six different TAN (Total Ammonia Nitrogen) values (262mg/L (control), 1000, 1500, 2000, 2500, 3000). The proposed model has a considerably more convenient form compared to other models that have been used in the literature for similar purposes. For example, the model facilitates the calculation of quantities such as the optimal pH as a function of TAN concentration, or the TAN concentration leading to 50% inhibition (TAN(50)) as a function of pH. High levels of correlations were achieved by the application of the proposed model to the experimental data obtained during our studies.Publication Metadata only Effects of insufficient air injection on methanogenic Archaea in landfill bioreactor(ELSEVIER, 2007) ÇALLI, BARIŞ; Mertoglu, Bulent; Calli, Baris; Guler, Nuray; Inanc, Bulent; Inoue, YuzoIn this study, methanogenic Archaea diversity in an aerated landfill bioreactor filled with co-disposed incineration bottom ashes and shredded incombustible wastes was monitored and analyzed as a function of time using molecular techniques. Besides, the effects of insufficient air injection on the bioreactor performance and methanogenic diversity were evaluated thoroughly. Results indicated that rapid bio-stabilization of solid waste are possible with aerated landfill bioreactor at various oxygen and oxidation reduction potential levels. Slot-blot hybridization results of leachate samples collected from aerated landfill bioreactor showed that archaeal and bacterial activities increased as stabilization accelerated and bacterial populations constituted almost 95% of all microorganisms. The results of slot-blot hybridization and phylogenetic analysis based on 16S rRNA gene revealed that Methanobacteriales and Methanomicrobiales were dominant species at the beginning while substituted by Methanosarcina-related methanogens close to the end of the operation of bioreactor. (c) 2006 Elsevier B.V. All rights reserved.