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SEMERCİ, NESLİHAN

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SEMERCİ

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NESLİHAN

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Now showing 1 - 2 of 2
  • Publication
    Phosphorus recovery from sewage sludge ash with bioleaching and electrodialysis
    (ELSEVIER SCI LTD, 2019) ÇALLI, BARIŞ; Semerci, Neslihan; Kunt, Busra; Calli, Baris
    Phosphorus is an essential element for all living organisms and for plants. However, phosphate rock, which is the main source of phosphorus, is limited and thus it must be recovered from secondary sources like sewage sludge ash (SSA). SSA is one of the most promising secondary sources because it contains considerable amounts of phosphorus. The drawback of SSA as a secondary source is the presence of heavy metals along with phosphorus. In this study, a bioleaching process was applied to solubilize the phosphorus more economically, thus bioleaching bacteria was used to obtain acidic conditions for phosphorus leaching. For this purpose, batch bioleaching experiments were carried out with Sulfur oxidizing bacteria (SOB) to optimize the process in terms of phosphorus dissolution. Experiments were conducted with different amounts of ash, inoculum volumes, and sulfur concentrations. Because the application of the bioleaching process leads to solubilization of heavy metals beside phosphorus, an electrodialysis process was used to separate phosphorus from heavy metals. Electrodialysis experiments were performed in a 3 compartment electrodialysis reactor with gold coated copper electrodes. The maximum phosphorus bioleaching was obtained with 2 g of ash, 40% inoculum, and 10 g.l(-1) elemental sulfur. Electrodialysis studies with gold coated copper electrodes lasted for 14 days and 24.6% of the phosphorus was transported to the anode.
  • Publication
    Fate of carbon, nitrogen and phosphorus removal in a post-anoxic system treating low strength wastewater
    (ELSEVIER SCI LTD, 2016) SEMERCİ, NESLİHAN; Semerci, Neslihan; Hasilci, Nevin Bakici
    A lab-scale anaerobic-aerobic-anoxic sequencing batch reactor was operated for 135 days with using acetate as sole carbon source to explore the contribution of denitrifying phosphate accumulating organisms to nitrogen and phosphorus removal in a post-anoxic system. The system was operated at an aerobic sludge age of 2.5 days and DO level greater than 2 mg l(-1)under variable carbon to nitrogen (C/N) and carbon to phosphorus (C/P) ratios. More than 80% of influent nitrogen and phosphorus were removed simultaneously under aerobic conditions. When aerobic denitrification became limited due to the increase of average dissolved oxygen, overall nitrogen removal continued with the same efficiency, but with a larger contribution from anoxic denitrification. On the other hand, enhanced biological phosphorus removal activity decreased significantly as a result of free nitrous acid (FNA) inhibition. Fluorescence in situ hybridization analysis showed that the relative abundance of Actinobacter spp. was decreased by FNA inhibition while the relative abundance of Accumulibacter spp. remained unchanged. Conversely, the relative abundance of glycogen accumulating organisms (GAOs) increased from 7.1% to 23% as a result. (C) 2015 Elsevier Ltd. All rights reserved.