G. Eremektar

Istanbul Technical University, İstanbul, Istanbul, Turkey

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Publications (16)21.62 Total impact

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    ABSTRACT: The acute toxicity of two biocides frequently used in textile finishing as broad-spectrum antibacterial/antifungal agents was studied using the marine algae Phaeodactylum tricornutum and a standard activated sludge inhibition test (ISO 8192). The influence of ozonation on several environmental sum parameters was also assessed. Both biocides exhibited significant toxicity toward the test organisms studied. Ozonation at elevated pH (11.5) and high doses (3.0-3.4 mg O3/mg COD0) was necessary for an acceptable reduction in the examined collective environmental parameters. The activated sludge inhibition tests revealed that 30 min of ozonation corresponding to a dose of 1.7-1.9 mg O3/mg COD0 accounted for practically complete detoxification of the aqueous biocides, while for the marine algae test, complete toxicity reduction could not be achieved after 30 min of ozonation.
    Aatcc Review 05/2006; 6(5):43-48. · 0.25 Impact Factor
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    ABSTRACT: The textile industry is confronted with serious environmental problems associated with its immense wastewater discharge, substantial pollution load, extremely high salinity, and alkaline, heavily coloured effluent. Particular sources of recalcitrance and toxicity in dyehouse effluent are two frequently used textile auxiliaries; i.e. dye carriers and biocidal finishing agents. The present experimental work reports the observation of scientific and practical significance related with the effect of two commercially important textile dye carriers and two biocidal finishing agents on biological activated sludge treatment at a textile preparation, dyeing and finishing plant in Istanbul. Respirometric measurements of the dyehouse effluent spiked with the selected textile chemicals were carried out for the assessment of the "readily biodegradable COD fraction" of the wastewater. The respirometric data obtained to visualize the effect of the selected textile auxiliaries on biomass activity was evaluated by an adopted activated sludge model. Results have indicated that the tested biocides did not exert any significant inhibitory effect on the treatment performance of the activated sludge reactor at the concentrations usually encountered in the final, total dyehouse effluent. The situation with the dye carriers was inherently different; one dye carrier appeared to be highly toxic and caused serious inhibition of the microbial respirometric activity, whereas the other dye carrier, also known as the more ecological alternative, i.e. the "Eco-Carrier", appeared to be biodegradable. Finally, the respirometric profile obtained for the Eco-Carrier was described by a simplified respirometric model.
    Chemosphere 04/2006; 62(9):1549-57. DOI:10.1016/j.chemosphere.2005.06.010 · 3.34 Impact Factor
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    ABSTRACT: In the present study, the decomposition of two biocides used in the textile finishing process with Advanced Oxidation Processes (AOPs) has been studied. Different AOPs, i.e O3/OH-, TiO2/UV-A and Fe2+/H2O2 have been used representing mutually combined components of the chemically and photochemically driven advanced oxidation systems. The course of reaction was examined by changes in chemical oxygen demand (COD), total organic carbon (TOC) and acute toxicity towards the water flea Daphnia magna (assessed in terms of the effective dilution ratio LD50). Particular attention has been paid to determine the inhibitory effect of raw and ozonated biocides on biological activated sludge consortium at concentrations typically encountered in textile finishing effluents. Significant oxidation and mineralization of both biocides could be achieved employing ozonation at pH = 11.5 and heterogeneous photocatalysis (TiO2/UV-A) at pH = 5.0, whereas Fenton's reagent appeared to be less effective in COD and acute toxicity abatement.
    Water Science & Technology 02/2005; 52(10-11):309-16. · 1.11 Impact Factor
  • G. Kutluay · F. Germirli Babuna · G. Eremektar · D. Orhon ·
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    ABSTRACT: In this study the wastewaters generated from a water-based paint industry have been investigated with respect to their chemical treatability. As the industry under consideration currently houses sludge drying beds and a chemical treatment facility that consists of an equalization basin, a rapid mixing tank, a slow mixing tank and a sedimentation unit, the main objective of the study was to find out the optimum sodium bentonite dosage applicable to meet the effluent discharge standards by using the existing treatment plant. A wastewater volume of 0.23 m3 per ton of water-based paint is produced by the process. The achieved pollutant removal efficiencies, sludge characteristics and calculated running costs covering sludge disposal and expenses of chemicals used show the introduction of a bentonite dosage of 500 mg/l at the original pH of the effluent as the optimum treatment alternative. The last part of the study is dedicated to evaluate the effect of optimum bentonite application on COD values of different molecular weight cut-off fractions. The results obtained indicate approximately 62 % of the COD originated from the fraction over 1.2 μm, where highest COD removal efficiency is achieved with sodium bentonite.
    Fresenius Environmental Bulletin 01/2004; 13(10):1057-1060. · 0.38 Impact Factor
  • Derin Orhon · Kutluay.G · Germirli Babuna.F · Eremektar.G ·

    Fresenius Environmental Bulletin 01/2004; 13(10):1057-1060. · 0.38 Impact Factor
  • Süreyya Meriç · Gülen Eremektar · Fehiman Ciner · Olcay Tünay ·
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    ABSTRACT: This study uses the oxygen uptake rate (OUR) measurement to measure toxicity effects of 2,4-dichlorophenoxyacetic acid (2,4-D) on activated sludges fed with the wastewater from a small domestic wastewater treatment plant and peptone-based synthetic wastewater. Two 2l lab-scale batch reactors were run in parallel with the same F/M ratios (0.4 mg COD per mg VSS per day) to assess the inhibition effects of 2,4-D concentrations between 25 and 75 mg l(-1) considering at least a 100% dilution rate, as compared with a pesticide industry effluent containing 20,000-40,000 mg l(-1) COD, reaches a central treatment plant. It was noted that the OUR was decreased to 15 and 30%, respectively, when adding 75 mg l(-1) of 2,4-D to the domestic and synthetic reactors. Meanwhile, the addition of 25 plus 50 mg l(-1) of 2,4-D in sequence to the domestic wastewater reactor did not significantly affect the OUR profile. The OUR-based inhibition definition has been used in this research since the OUR methods have been frequently used and cited in the literature to study toxicity effects. However, the origin of the sludge used in the testing is also important. Synthetic wastewater may simulate the toxicity studies but with a higher response than actual systems, since the microorganisms are considerably becoming substrate-selective.
    Journal of Hazardous Materials 08/2003; 101(2):147-55. DOI:10.1016/S0304-3894(03)00147-X · 4.53 Impact Factor
  • H Dulkadiroglu · G Eremektar · S Dogruel · H Uner · F Germirli-Babuna · D Orhon ·
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    ABSTRACT: Water minimization and exploration of the potential for wastewater recovery and reuse are priority issues of industrial wastewater management. They are extremely significant for the textile industry commonly characterized with a high water demand. The study presents a detailed in-plant control survey for a wool finishing plant. A comprehensive process profile and wastewater characterization indicate that process water consumption can be reduced by 34%, and 23% of the wastewater volume can be recovered for reuse. Treatability of reusable wastewater fraction and the effect of in-plant control applications on effluent treatability were also investigated.
    Water Science & Technology 02/2002; 45(12):287-95. · 1.11 Impact Factor
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    G Eremektar · O Karahan-Gul · F Germirli-Babuna · S Ovez · H Uner · D Orhon ·
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    ABSTRACT: Corn wet mill effluents are studied in terms of their characteristics relevant for biological treatment. They have a high COD of mainly soluble and biodegradable nature, with practically no soluble inert components. They generate a relatively high level of soluble residual metabolic products, which affects the choice of the appropriate biological treatment and favors aerobic activated sludge process. Experimental assessment of process kinetics yields typical values. Hydrolysis of the slowly biodegradable COD, the rate limiting step for the utilization of substrate, is characterized by an overall rate coefficient, which is within the range commonly associated for the hydrolysis of starch.
    Water Science & Technology 02/2002; 45(12):339-46. · 1.11 Impact Factor
  • G. Eremektar · F. Germirli Babuna · O. Ince ·
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    ABSTRACT: In this study, the effluent of an alcohol distillery after passing through a chemical treatment is characterized in terms of its inert COD Suctions and the changes likely to be induced by two‐stage biological treatment on the magnitude of these fractions are observed. The experimentally obtained results indicated that the anaerobic treatment gives lower soluble inert COD fractions than a corresponding aerobic treatment for the investigated wastewater. Therefore, the preference of anaerobic treatment instead of an aerobic one as the first stage is ascertained. The anaerobic first stage has a COD removal efficiency of 96 %, whereas with a subsequent aerobic treatment 79 % removal can be achieved on the basis of the stoichiometry of the inert COD. The anaerobic full‐scale plant performance of 80 % can be improved up to 96 %.
    Journal of Environmental Science and Health Part A 06/1999; A34(6-6):1329-1340. DOI:10.1080/10934529909376899 · 1.16 Impact Factor
  • F. Germirli Babuna · B. Soyhan · G. Eremektar · D. Orhon ·
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    ABSTRACT: The study emphasizes wastewater characteristics of two different textile plants as they apply to biological treatment. Although conventional characterization reveals no major differences, the effluents from the acrylic fiber and yarn dyeing plant exhibit all the properties of a non-biodegradable wastewater. Appropriate pretreatment consisting of partial chemical oxidation with H2O2 reduces its COD content to 700 mg I−1, almost entirely biodegradable whereas COD fractionation indicates that the effluents of the cotton knit dyeing plant contain 9% residual fractions. Experimental investigation shows that most kinetic and stoichiometric properties of both wastewaters are compatible with that of domestic sewage with the exception of a much slower hydrolysis rate.
    Water Science & Technology 01/1999; 40(1):145–152. · 1.11 Impact Factor
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    ABSTRACT: Poultry processing generates strong wastewaters with characteristics that may be tailored by appropriate adjustment of the operation. The organic content has a residual fraction in the order of 200–400 mgl−1, depending on the strength of the wastewater. The values of kinetic and stoichiometric constants related to biological treatability are observed to be quite comparable with domestic sewage. The hydrolysis of slowly biodegradable organics is best described by dual-hydrolysis kinetics with appreciably different rate constants for soluble and particulate components. The experimental results of the study may be used to evaluate the achievable compliance with existing effluent limitations and to define the optimum in-plant operation and wastewater treatment and disposal strategy.
    Water Science & Technology 01/1999; 40(1):323-329. DOI:10.1016/S0273-1223(99)00401-1 · 1.11 Impact Factor
  • F. Germirli Babuna · E. Çekyay · G. Eremektar · D. Orhon ·
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    ABSTRACT: Modern laying chicken plants generate strong wastewaters of limited flow rate, with COD concentrations up around to 10 g I−1, with a soluble portion of 50% and high nitrogen and phosphorus contents. The unit wastewater flow is as low as 0.003–0.005 I chicken−1 day+ and the unit organic load is assessed as 0.03 g COD chicken−1 day−1. COD fractionation reveals that the soluble residual portion accounts for 350 mg I−1 in the chicks step and 980 mg I−1 in the laying step for aerobic treatment. When anaerobic treatment is applied this residual fraction is likely to exhibit an increase of around 60 to 80%. These observations underline the significance and the need of setting effluent limitations attainable by biological treatment, if evidence is presented that they do not pose appreciable environmental problems such as toxicity, colour, etc. This is especially true for laying chicken plant effluents, due to their intermittent mode of generation and their limited volume.
    Water Science & Technology 01/1999; 40(1):207–213. · 1.11 Impact Factor
  • Gülen Eremektar · Fatos Germirli Babuna · Derin Orhon ·
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    ABSTRACT: Two-stage biological treatment schemes are often prescribed for pulp and paper mill effluents with high COD concentrations, in order to meet effluent standards. Recent conceptual developments in biological treatment of wastewaters indicate that the stoichiometry of the inert organic components is the key issue in performance predictions and the kinetics of degradable organic fraction play a relatively less important role in the compliance of effluent limitations. Besides, the differentiation between initially inert COD and inert metabolic products is very important in two-stage systems, as what is biodegradable for one phase may become non-biodegradable for the next phase in which a different microbial community is sustained. In this study a pulp and paper mill effluent is characterized in terms of its inert COD fractions and the changes induced by two-stage biological treatment to these fractions are observed. © 1998 SCI
    Journal of Chemical Technology & Biotechnology 05/1998; 72(1):7 - 14. DOI:10.1002/(SICI)1097-4660(199805)72:1<7::AID-JCTB862>3.0.CO;2-8 · 2.35 Impact Factor
  • O. Tünay · K. Alp · I. Kabdaşh · Ş. Çeviker · G. Eremektar ·
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    ABSTRACT: Increasing demand for the toxic metal control has led to search of more effective methods for heavy metal treatment. Chemical reduction is among the methods recently developed. In this study applicability of chemical reduction is experimentally evaluated using NaBH4 as reducer and nickel solution to assess the performance of the chemical reduction for wastewaters of complexed metal category. EDTA and acetic acid are used as organic ligands. Results indicated that reduction of Ni2+ to elemental nickel (Ni0) state can be carried out above pH 12 without being affected from the existence of organic ligands. Lower pH experiments is shown that Ni2B is not precipitated at lower pH. Effect of reducing agent on regular hydroxide precipitation is also experimentally evaluated and no significant effect has been observed.
    Fresenius Environmental Bulletin 01/1997; 6(5):278-283. · 0.38 Impact Factor
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    ABSTRACT: The requirement of color removal has promoted the research in this field. However, there is still a lack of understanding of colour problems. In this paper a literature review is made to assess the information on color removal and need for systematic evaluation of the results is emphasized. Experimental studies are conducted on the textile dyeing wastewaters applying chemical precipitation, chemical oxidation, adsorption and their combination. Results of the study are evaluated and discussed within the context of a systematic approach.
    Water Science & Technology 01/1996; 34(11):9-16. DOI:10.1016/S0273-1223(96)00815-3 · 1.11 Impact Factor
  • G. Eremektar · O. Tünay · D. Orhon · E. Gönenç ·
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    ABSTRACT: Fermentation of molasses and refining the produced alcohol by distillation is a common agroindustrial activity. The wastewaters originating from the process, especially the spent mash, are highly concentrated and contain TDS of over 50,000 mg/1 as well as organic matter. Character of wastewaters varies with production application which affects the treatability characteristics. In this study four alcohol distillery plants treating beet sugar molasses are investigated to assess production applications and wastewater characteristics. Process profiles for three major modes of operation are prepared. Use of open steam and recycle of spent mash was calculated to affect the wastewater volume up to 25%. COD load is found to be practically unchanged with recycle while TDS increased significantly. Nature of COD and treatability characteristics are also expected to vary with recycle.
    Water Science & Technology 01/1995; 32(12):181–188. · 1.11 Impact Factor