Person: ÇALLI, BARIŞ
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ÇALLI
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BARIŞ
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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 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 high free ammonia concentrations on the performances of anaerobic bioreactors(ELSEVIER SCI LTD, 2005) ÇALLI, BARIŞ; Calli, B; Mertoglu, B; Inanc, B; Yenigun, OUASB reactors inoculated with different seed sludges were operated for 450 days under high ammonia concentrations to investigate inhibition effects. Reactors were fed with synthetic wastewater providing an organic loading of about 1.2 kg COD m(3) /day and having total ammonia nitrogen (TAN) concentrations gradually increasing from 1000 to 6000 mg/l. As, corresponding free ammonia nitrogen (FAN) concentrations elevated up to 800 mg/l, COD removal efficiencies in the range of 78-96% were determined. High removal efficiencies revealed that seed sludges taken from anaerobic reactors treating considerably low ammonia containing wastewaters have adapted to elevated free ammonia concentrations successfully. However, propionate accumulation in some reactors and decrease in eubacterial signals detected by fluorescent in situ hybridization (FISH) indicated that propionate degrading acetogenic bacteria are more sensitive than methanogenic archaea to free ammonia. Differences in the efficiencies of reactors were correlated with the quantity of resistant and sensitive microorganisms dominated in the reactors. (C) 2004 Elsevier Ltd. All rights reserved.Publication Metadata only Anaerobic fermentation of organic solid wastes: volatile fatty acid production and separation(IWA PUBLISHING, 2014) TUĞTAŞ KARNABAT, ADİLE EVREN; Yesil, H.; Tugtas, A. E.; Bayrakdar, A.; Calli, B.Anaerobic fermentation of organic municipal solid waste was investigated using a leach-bed reactor (LBR) to assess the volatile fatty acid (VFA) production efficiency. The leachate recycle rate in the LBR affected the VFA composition of the leachate. A six-fold increase in the recycle rate resulted in an increase of the acetic acid fraction of leachate from 24.7 to 43.0%. The separation of VFAs via leachate replacement resulted in higher total VFA production. VFA separation from synthetic VFA mix and leachate of a fermented organic waste was assessed via a counter-current flow polytetrafluoroethylene (PTFE) membrane contactor. Acetic and propionic acid permeation fluxes of 13.12 and 14.21 g/m(2).h were obtained at low feed pH values when a synthetic VFA mix was used as a feed solution. The highest selectivity was obtained for caproic acid compared to that of other VFAs when synthetic VFA mix or leachate was used as a feed solution. High pH values and the presence of suspended solids in the leachate adversely affected the permeation rate.Publication Metadata only Ammonia and pH inhibition in anaerobic treatment of wastewaters, part I: Experimental(TAYLOR & FRANCIS INC, 2004) ÇALLI, BARIŞ; Eldem, NO; Ozturk, I; Soyer, E; Calli, B; Akgiray, OThe influences of pH and ammonia on methane production in the anaerobic treatment of in acetic-propionic-butyric acid mixture in batch reactors operated at 37degreesC were investigated. Two independent sets of experiments were carried out using seeds from two different full-scale industrial anaerobic treatment reactors. One of the seeds (Sludge A) was obtained from an upflow anaerobic sludge-blanket (UASB) reactor treating the waste from a potato chips production plant. The second sludge seed (Sludge B) was from an expanded granular sludge-blanket (EGSB) reactor treating a corn processing waste. Experiments were carried out 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). Three vials (triple runs) were used for each pH and TAN value. The sludge seeds used in the inhibition tests were not exposed to high levels of ammonia at any stage before the tests. For each vial, cumulative methane production was monitored for a period long enough for the termination of biogas production. Although neither sludge was acclimated to ammonia, the lag-phase times were less than 2 days for Sludge A and essentially zero for Sludge B for all TAN and pH values. At certain high pH and high TAN values, however, methanogenic activity ceased within about 1-3 months; and then activity restarted and methane formation rate reached its maximum values after this period. If the experiments had not been continued following this period, this reactivation phenomenon would not have been detected.Publication Metadata only Treatment of synthetic wastewater and cheese whey by the anaerobic dynamic membrane bioreactor(SPRINGER HEIDELBERG, 2019) ÇALLI, BARIŞ; Pacal, Muge; Semerci, Neslihan; Calli, BarisThe aim of this study was to develop a laboratory-scale anaerobic dynamic membrane bioreactor (AnDMBR) for the treatment of high-strength synthetic and real cheese whey wastewater. We determined the appropriate pore size for a convenient type of support material (nylon mesh) to optimize cake layer formation. The performance of the AnDMBRs was measured in terms of chemical oxygen demand (COD) and solids removal efficiencies. During high-strength synthetic wastewater treatment, the 70-mu m pore size AnDMBR achieved COD removal efficiencies of 78% and 96% with COD loading rates of 4.03 and 2.34 kg m(-3) day(-1), respectively, while the 10-mu m pore size AnDMBR achieved 66% and 92% COD removal efficiencies at COD loading rates of 5.02 and 3.16 kg m(-3) day(-1). The 10 mu m pore size AnDMBR was operated in two periods: first period and second period (before and after physical cleaning) during high-strength synthetic wastewater treatment. The 10-mu m pore size AnDMBR removed 83% and 88% of suspended solids during period 1 and period 2, respectively. Furthermore, using a pore size of 10 mu m retained 72% of solids (973 mg L-1) in the reactor outlet. The 10-mu m pore size AnDMBR performed better than the 70-mu m pore size AnDMBR in terms of cake layer formation. The 10-mu m pore size AnDMBR was used to treat real cheese whey wastewater, resulting in COD removal efficiencies ranging from 59% (4.32 kg m(-3) day(-1)) to 97% (5.22 kg m(-3) day(-1)). In addition, 85% of suspended solids were removed from real cheese whey wastewater after treatment. The results show that dynamic membrane technology using a pore size of 10 mu m can be used to treat real industrial wastewater.Publication Metadata only Methanogenic diversity in anaerobic bioreactors under extremely high ammonia levels(ELSEVIER SCIENCE INC, 2005) ÇALLI, BARIŞ; Calli, B; Mertoglu, B; Inanc, B; Yenigun, OTo evaluate the effects of high free ammonia nitrogen on methanogens, five laboratory scale UASB reactors seeded with different sludges were operated for 450 days. Throughout the experimental period, free ammonia concentration was gradually elevated up to 750 mg/l. Changes in methanogenic population were investigated by using 16S rDNA/rRNA based molecular methods such as denaturing gradient gel electrophoresis (DGGE), fluorescent in situ hybridization (FISH), cloning and DNA sequencing. Generally, in all of the reactors, moderately high COD removal was achieved in the range of 77-96%. However, in three of the reactors, propionate degradation and in one of them, acetate removal was influenced more severely. In no way, neither of the phases was inhibited in reactor 4 (R4), which was seeded with a biomass concentrated from a landfill leachate. On the other hand, as free ammonia level elevated, instead of a community shift, single coccus shaped Methanosarcina cells previously predominant at low free ammonia concentrations turned into stringent multicellular units, in all of the reactors. (c) 2005 Elsevier Inc. All rights reserved.