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ÇALLI, BARIŞ

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Author: MERTOĞLU, BÜLENT × Subject: DIGESTION ×

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    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, O
    UASB 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.
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    Methanogenic diversity in anaerobic bioreactors under extremely high ammonia levels
    (ELSEVIER SCIENCE INC, 2005) ÇALLI, BARIŞ; Calli, B; Mertoglu, B; Inanc, B; Yenigun, O
    To 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.