Person: MERTOĞLU, BÜLENT
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MERTOĞLU
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BÜLENT
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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 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.Publication Metadata only Landfill leachate management in Istanbul: applications and alternatives(PERGAMON-ELSEVIER SCIENCE LTD, 2005) ÇALLI, BARIŞ; Calli, B; Mertoglu, B; Inanc, BTreatment alternatives for Istanbul, Komurcuoda Landfill (KL) leachate that is currently transported to the nearest central wastewater treatment plant were comprehensively investigated with laboratory scale experiments. As flow rate of leachate increases parallel to increment in landfilled solid waste, an individual treatment will be needed to reduce the transportation cost and pollution load on central treatment. However, if the leachate is separately treated and discharged to a brook, in that case more stringent discharge standards will be valid and therefore advanced processes in addition to conventional ones should be included. In laboratory scale experiments, the young landfill leachate having BOD5/COD ratio above 0.6 was successfully treated with efficiencies above 90% in upflow anaerobic reactors if pH is kept below free ammonia inhibition level. Subsequently, nitrification of anaerobically treated leachate was performed with rates of about 8.5 mg NH4+-Ng(-1) VSS h(-1) and efficiencies above 99% were provided with automated pH regulation by using sodium bicarbonate. Furthermore, denitrification rates as high as 8.1 mg NOx-Ng(-1) VSS h(-1) was obtained when carbon source was externally supplied. In addition to nitrification and denitrification, air stripping and struvite precipitation were also applied to remove ammonia in leachate and in average 94% and 98% efficiencies were achieved, respectively. Finally, in average 85% of biologically inert COD was successfully removed by using either ozone or Fenton's oxidation. © 2004 Elsevier Ltd. All rights reserved.Publication Metadata only Evaluation of in situ ammonia removal in an aerated landfill bioreactor(ELSEVIER SCI LTD, 2006) ÇALLI, BARIŞ; Mertoglu, Bulent; Calli, Baris; Inanc, Bulent; Ozturk, IzzetThe composition of nitrifying bacteria in an aerated landfill bioreactor filled with municipal solid waste incineration bottom ashes and shredded incombustible wastes was monitored and analyzed as a function of time during 1 year operation using molecular techniques. Besides, the effects of differing operational conditions on the bioreactor performance and diversity of nitrifiers were evaluated thoroughly. The results confirmed the viability of rapid aerobic bio-stabilization in an aerated landfill bioreactor operated at various ORP levels (-400 to 150 mV). BOD5 decreased faster than TOC and dropped below 10 mg/l after day 120. Subsequently, it remained quite constant until the end of the operational period. This rapid BOD5 degradation in the aerated landfill bioreactor increased the possibility of nitrification by promoting nitrifying bacteria having high oxygen affinities. The nitrification activity in the bioreactor was approved by identification of intensive amounts of Nitrosomonas-like ammonia oxidizers and Nitrospira related nitrite oxidizers with 16S rDNA and amoA based molecular microbiology techniques. (c) 2006 Elsevier Ltd. All rights reserved.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 Molecular analysis of microbial communities in nitrification and denitrification reactors treating high ammonia leachate(2003) ÇALLI, BARIŞ; Calli, Baris; Tas, Neslihan; Mertoglu, Bulent; Inanc, Bulent; Ozturk, IzzetMolecular analysis of microbial populations in two bench-scale nitrification and denitrification reactors fed with high ammonia landfill leachate was conducted in this study by using DGGE, cloning, and FISH techniques in addition to classical efficiency control parameters. Nitrification tank was operated with a computer-controlled alkalinity dosing system to supply the alkalinity intermittently as consumed on the basis of on-line pH monitoring. By keeping the pH at 7.0 with this system, 99% nitrification efficiency and rates of about 0.14-0.18 mgNH4+-N/mgVSSday were obtained. Meanwhile, as ammonia oxidizing bacteria Nitrosomonas and Nitrosococcus mobilis-like cells and as nitrite oxidizing bacteria Nitrobacter-related cells were intensively indicated. Moreover, some aerobic denitrifiers as Thauera species were also identified. After the termination of pH adjustment in the preceding anaerobic reactors, nitrification tank was loaded with more biodegradable COD as a result of reduced COD removal in anaerobic reactors. Microbial diversity was immediately affected from this alteration and heterotrophic carbonaceous bacteria and aerobic denitrifiers have dominated. To provide the former high efficiencies, retention time has increased from 24 to 48 h and a second pump dosing HCl was included to the automatic control system. Subsequent to these precautions, numbers of ammonia (Nso190) and nitrite oxidizing bacteria (NIT3) were comparatively increased. In denitrification system, about 98% denitrification efficiencies were obtained at 2000 mg/L NOx-N concentrations if sodium acetate was supplied as carbon source. Meanwhile, with 20 gVSS/l biomass concentration, denitrification rates of about 1.34 mgNOx-N/mgVSSday were obtained. All sludge samples have represented similar DGGE patterns and Paraccoccus-related species were identified as dominant denitrifying bacteria.Publication Metadata only Comparative analysis of nitrifying bacteria in full-scale oxidation ditch and aerated nitrification biofilter by using fluorescent in situ hybridization (FISH) and denaturing gradient gel electrophoresis (DGGE)(2005) ÇALLI, BARIŞ; Mertoglu, Bulent; Calli, Baris; Girgin, Emine; Inanc, Bulent; Ozturk, IzzetIn this study, nitrification performances and composition of nitrifying populations in a full-scale oxidation ditch and a high-rate submerged media nitrification biofilter were comparatively analyzed. In addition to different reactor configurations, effects of differing operational conditions on the nitrification efficiency and bacterial diversity were also explored and evaluated thoroughly. In microbial analysis of sludge samples fluorescent in situ hybridization (FISH) and denaturing gradient gel electrophoresis (DGGE) techniques were used complementary to each other. The extended aeration oxidation ditch subjected to the study is operated as a nitrogen and phosphorus removal system consisting of anaerobic, anoxic, and aerobic zones. The high-rate submerged media aerated filter is operated as nitrification step following the conventional activated sludge unit and the nitrified wastewater is discharged to the sea without complete nitrogen removal. In situ hybridization results have indicated that Nitrosomonas-like ammonia oxidizing and Nitrospira-related nitrite oxidizing bacteria were intensively present in vigorous flocs in nitrification biofilter while carbonaceous bacteria belong to beta subclass of Proteobacteria were considerably dominant in oxidation ditch. Low quantities of nitrifiers in oxidation ditch were also confirmed by the dissimilarity in intensive bands between two systems obtained with DGGE analysis.Publication Metadata only Identification of prevalent microbial communities in a municipal solid waste landfill(I W A PUBLISHING, 2006) ÇALLI, BARIŞ; Calli, B; Durmaz, S; Mertoglu, BTo identify the microbial communities in Istanbul, Odayeri Municipal Solid Waste Landfill, leachate samples were collected from different sections at different stabilization phases. In identification of microbial communities in leachate samples, molecular techniques such as FISH, DGGE and cloning based on 16S rRNA and mcrA genes were used. As the chemical and microbiological compositions of the samples were compared, obvious correlations were found between the stability of the landfill section and abundance of active methanogens. On the other hand, there were considerable differences between acidogenic and mature leachate samples in DGGE profiles of archaeal and bacterial 16S rRNA genes. Moreover, in acidogenic leachate samples having BOD5/COD ratio of about 0.5 acetate utilizing Methanosarcina and Methanosaeta species were intensively detected in FISH. Although only very few H-2-utilizing methanogens were identified with FISH analysis, most of the clones isolated from mature leachate samples clustered within H-2-utilizing Methanobacteriales and Methanomicrobiales according to phylogenetic analysis of 16S rRNA and mcrA clones, respectively.Publication Metadata only Extremely halophilic Archaea from Tuz Lake, Turkey, and the adjacent Kaldirim and Kayacik salterns(SPRINGER, 2007) OGAN, AYŞE; Birbir, Meral; Calli, Baris; Mertoglu, Bulent; Bardavid, Rahel Elevi; Oren, Aharon; Ogmen, Mehmet Nuri; Ogan, AyseTuz Lake is a hypersaline lake located in Central Anatolia, Turkey. The lake and its salterns, Kaldirim and Kayacik, are the major sources of solar salt for industrial applications in Turkey, especially in the food and leather industries. Use of the crude solar salt often results in microbial deterioration of the products. We therefore initiated a thorough characterization of the microbial communities in Tuz Lake and its adjacent salterns, and we present here the results of investigations on diversity of extremely halophilic Archaea. Twenty-seven colonies of aerobic red or pink Archaea (family Halobacteriaceae) were selected according to colony shape, size, consistency and pigmentation, and characterized according to their phenotypic characteristics, polar lipid contents, and antibiotic sensitivities. Furthermore, 16S rRNA genes of the isolates were screened by DGGE analysis and partially sequenced. Phylogenetic analysis showed that most isolates belonged to the genera Haloarcula, Halorubrum and Halobacterium. Haloarcula was found to be dominant both in Tuz Lake and in the saltern samples. Halorubrum species were isolated from Tuz Lake and from the Kaldirim saltern, and Halobacterium species were recovered from Tuz Lake and from the Kayacik saltern. All strains showed various activities of hydrolytic enzymes (proteases, amylases, cellulases, and others), activities which are responsible for the detrimental effects of the crude salt in food and leather products.Publication Metadata only Comparison of long-term performances and final microbial compositions of anaerobic reactors treating landfill leachate(ELSEVIER SCI LTD, 2006) ÇALLI, BARIŞ; Calli, B; Mertoglu, B; Roest, K; Inanc, BLaboratory scale anaerobic upflow filter, sludge blanket and hybrid bed reactors were operated for 860 days in the treatment of high ammonia landfill leachate. Organic loading was gradually increased from 1.3 to 23.5 kg COD/m(3) day in the start-up period and then fluctuated according to the COD concentration of raw leachate. To prevent free ammonia inhibition, influent pH was reduced to 4.5 after Day 181 and consequently COD removal efficiencies above 80% were achieved in all reactors. However, the anaerobic filter and hybrid bed reactor were generally found slightly more efficient and stable than the UASB reactor. In addition to conventional anaerobic reactor control parameters, the complementary techniques of denaturing gradient gel electrophoresis (DGGE), cloning and fluorescent in situ hybridization (FISH) were used to identify and compare the microbial profiles in the reactors at Day 830. Molecular analyses revealed that acetoclastic Methanosaeta species were prevalent in all reactors and configuration did not have an impact on microbial diversity in the long-term. (c) 2005 Elsevier Ltd. All rights reserved.