Person: KALKAN AKTAN, ÇİĞDEM
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KALKAN AKTAN
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ÇİĞDEM
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Publication Metadata only Speciation of nickel and zinc, its short-term inhibitory effect on anammox, and the associated microbial community composition(ELSEVIER SCI LTD, 2018) KALKAN AKTAN, ÇİĞDEM; Aktan, Cigdem Kalkan; Uzunhasanoglu, Ayse Ekin; Yapsakli, KozetThis study provides insight into the short-term effects of nickel and zinc on anammox. The impacts of these heavy metals are evaluated based on their potentially bioavailable fractions, including the intracellular, surface-bound, soluble, free-ion, and weak (labile) complexes of heavy metals, in the presence of certain inorganic/ organic species. Results showed that the IC50 values for soluble, intracellular, cell-associated, surface-bound, and free-ion Ni concentrations are 5.99, 0.250, 0.930, 0.680, and 1.36 mg/L, respectively. The inhibitory effect of Zn is found to be lower with respect to Ni, with 1050 values of 6.76, 11.9, 15.1, and 2.71 mg/L for the soluble, intracellular, cell-associated, and free-ion Zn concentrations, respectively. This is the first detailed evaluation of anammox inhibition based on the fractionation of heavy metals. Metagenomic analysis reveals that Candidates Kuenenia constitute approximately 89% of the entire Planctomycetes population, whereas Candidates Brocadia are detected in relatively low fractions (3%).Publication Metadata only Evaluation of Biological Activated Carbon (BAC) process in wastewater treatment secondary effluent for reclamation purposes(ELSEVIER SCIENCE BV, 2011) MERTOĞLU, BÜLENT; Kalkan, Cigdem; Yapsakli, Kozet; Mertoglu, Bulent; Tufan, Deniz; Saatci, AhmetThe effects of two different granular activated carbon (GAC) types (steam activated, PK1-3 and chemically activated, CAgran) on dissolved organic carbon (DOC) removal. nitrification and denitrification were evaluated in BAC columns for wastewater reclamation/reuse purposes. Continuous-flow laboratory-scale BAC columns were operated for 320 days using the secondary effluent water of Pasakoy Advanced Wastewater Treatment Plant. During the first 83 days of column operation, when adsorption was the dominant mechanism, the average DOC removal efficiency was 81% for PK1-3 and 64.5% for CAgran. Later on, the efficiencies dropped to 45.9% for PK 1-3 and 37.8% for CAgran. which shows the operational time period when breakthrough is reached and DOC removal is dominantly due to biodegradation. BAC columns were also capable of removing total nitrogen; removal efficiencies were observed to be 54.0% for the biofilter packed with PK1-3 and 51.5% for the one packed with CAgran. The results also showed that DOC and ammonia nitrogen concentrations immediately decrease due to dilution and biodegradation at the top of the BAC columns. This study establishes that a carefully operated BAC system, which was used for tertiary treatment of a secondary effluent, can remove organic carbon and total nitrogen to a significant extent. (C) 2010 Elsevier B.V. All rights reserved.Publication Metadata only Treatment of landfill leachate using UASB-MBR-SHARON-Anammox configuration(SPRINGER, 2013) MERTOĞLU, BÜLENT; Akgul, Deniz; Aktan, Cigdem Kalkan; Yapsakli, Kozet; Mertoglu, BulentLeachate treatment is a challenging issue due to its high pollutant loads. There are several studies on feasible treatment methods of leachate. In the scope of this study, high organic content of young leachate was eliminated using an upflow anaerobic sludge blanket (UASB) and a membrane bioreactor (MBR) in sequence and effluent of the system was given to single reactor for high activity ammonia removal over nitrite (SHARON) and anaerobic ammonia oxidation (Anammox) reactors to remove nitrogen content. All reactors were set up at lab scale in order to evaluate the usage of these processes in sequencing order for leachate treatment. COD and TKN removal efficiencies were over 90 % in the combined processes which were operated during the study. The biodegradable portion of organic matter was removed with an efficiency of 99 %. BOD5 concentration decreased to 50 mg/L by UASB and MBR in sequence even the influent BOD5 concentration was over 8,000 mg/L. Although high nitrogen concentrations were observed in raw leachate, successful removal of nitrogen was accomplished by consecutive operations of SHARON and Anammox reactors. The results of this study demonstrated that with an efficient pretreatment of leachate, the combination of SHARON-Anammox processes is an effective method for the treatment of high nitrogen content in leachate.Publication Metadata only Short- and long-term effects of copper on anammox under gradually increased copper concentrations(SPRINGER, 2021) MERTOĞLU, BÜLENT; Aktan, Cigdem Kalkan; Yapsakli, Kozet; Mertoglu, BulentThis study aims to determine both short- and long-term response of enriched anammox culture to Cu. Assessment of short-term inhibition is based both on total applied Cu concentration and potential bioavailable fractions like intracellular, surface-bound, soluble and free Cu ion. The half maximal inhibitory concentration (IC50) values for total applied, soluble, intracellular and cell-associated concentrations were determined as 4.57 mg/L, 1.97 mg/L, 0.71 mg/L, 1.11 mg/L, respectively. Correlation between the surface-bound fraction of Cu and inhibition response was weak, suggesting that Cu sorbed to biomass was not directly responsible for the effects on anammox activity. There was a disparity between the results of short- and long-term experiments in terms of inhibition threshold concentration (i.e. short-term IC50 = 4.57 mg/L vs long-term IC50 = 6.74 mg/L). Candidatus Kuenenia (59.8%) and Candidatus Brocadia (40.2%) were the two main anammox genera within the initial biomass sample. One of the most interesting finding of the study is the demonstration that a complete wash-out of C. Brocadia genus at an applied Cu concentration of 6.5 mg/L. This strongly indicates that C. Brocadia were not able to tolerate high copper concentrations and all nitrogen conversion was carried out by C. Kuenenia during the Cu exposure period.Publication Metadata only Anammox-zeolite system acting as buffer to achieve stable effluent nitrogen values(SPRINGER, 2017) MERTOĞLU, BÜLENT; Yapsakli, Kozet; Aktan, Cigdem Kalkan; Mertoglu, BulentFor a successful nitrogen removal, Anammox process needs to be established in line with a stable partial nitritation pretreatment unit since wastewater influent is mostly unsuitable for direct treatment by Anammox. Partial nitritation is, however, a critical bottleneck for the nitrogen removal since it is often difficult to maintain the right proportions of NO2-N and NH4-N during long periods of time for Anammox process. This study investigated the potential of Anammox-zeolite biofilter to buffer inequalities in nitrite and ammonium nitrogen in the influent feed. Anammox-zeolite biofilter combines the ion-exchange property of zeolite with the biological removal by Anammox process. Continuous-flow biofilter was operated for 570 days to test the response of Anammox-zeolite system for irregular ammonium and nitrite nitrogen entries. The reactor demonstrated stable and high nitrogen removal efficiencies (approximately 95 %) even when the influent NO2-N to NH4-N ratios were far from the stoichiometric ratio for Anammox reaction (i.e. NO2-N to NH4-N ranging from 0 to infinity). This is achieved by the sorption of surplus NH4-N by zeolite particles in case ammonium rich influent came in excess with respect to Anammox stoichiometry. Similarly, when ammonium-poor influent is fed to the reactor, ammonium desorption took place due to shifts in ion-exchange equilibrium and deficient amount were supplied by previously sorbed NH4-N. Here, zeolite acted as a preserving reservoir of ammonium where both sorption and desorption took place when needed and this caused the Anammox-zeolite system to act as a buffer system to generate a stable effluent.Publication Metadata only Inhibitory effects of free ammonia on Anammox bacteria(SPRINGER, 2012) MERTOĞLU, BÜLENT; Aktan, Cigdem Kalkan; Yapsakli, Kozet; Mertoglu, BulentAnammox bacteria can effectively treat high ammonia and nitrite concentrations under anoxic environments. However, the presence of high ammonia and nitrite concentrations may cause free ammonia and nitrous acid inhibition at high pH and temperature environments. In this study, the inhibitory effect of free ammonia on Anammox bacteria was investigated in a lab-scale upflow fixed-bed reactor with Kaldnes biofilm carriers. Results of continuous operation showed that inhibition was not observed in the Anammox reactor when the free ammonia concentration gradually increased up to 150 mg/L. However, Anammox activity suddenly dropped to 10 % when the free ammonia concentration reached to 190 mg/L. Nevertheless, high influent ammonia and nitrite concentrations up to 1,500 and 500 mg/L, respectively, did not noticeably inhibit the Anammox activity. Gradually decreasing Anammox activity was also supported by fluorescent in situ hybridization (FISH) analysis. FISH and 16S rRNA gene analysis results revealed that main Anammox organisms were phylogenetically related to Candidatus Kuenenia stuttgartiensis, Candidatus Jettenia asiatica and Candidatus Brocadia anammoxidans.