Endüstri Mühendisliği Bölümü Yayın Koleksiyonu

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End date: 2009Publisher: search.filters.publisher.Elsevier Sci Ltd

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  • Article
    Citation - WoS: 205
    Citation - Scopus: 231
    Ammonia Removal From Anaerobically Digested Dairy Manure by Struvite Precipitation
    (Elsevier Sci Ltd, 2005) Uludag-Demirer, S; Demirer, GN; Chen, S
    Ammonia is one of the most important contaminants impairing the quality of water resources. When this is considered along with the fact that the global demand for nitrogenous fertilizers is in constant rise, the need for recovery as well as removal of nitrogen is well justified. Crystallization of N and P in the form of struvite (MgNH4PO4 center dot 6H(2)O), which is a slow releasing and valuable fertilizer, is one possible technique for this purpose. This study investigated the removal of NR4+ through struvite precipitation from the effluents of one- (R1) and two-phase (R2) anaerobic reactors digesting dairy manure. To force the formation of struvite in the anaerobic reactor effluents, Ma(2+) ion was added by using both Mg(OH)(2) and MgCl2 center dot 6H(2)O. To prevent the effect of different total phosphorus (TP) concentration in the effluents of RI and R2, as well as to not limit the formation of struvite, an excess amount Of PO43- (0.14 M) was added in the form of NaHPO4. Different stoichiometric Mg2+:NH4+:PO43- ratios were tested to determine the required Mg2+ concentrations for maximum NH4+ removal by keeping NH4+:PO43- ratio constant for the effluents of reactors RI and R2. The results revealed that very high NH4+ removal efficiencies (above 95%) were possible by adding Mg 21 ions higher than 0.06 M concentration in the effluents from reactors RI and R2. It was also observed that the initial pH adjustment to 8.50 using NaOH did not result in any significant increase in the removal of NH4+ and the removal of NH4+ in the reactors treated with MgCl2 center dot 6H(2)O was higher than those treated with Mg(OH)(2) for the same Mg2+ concentration. (c) 2005 Published by Elsevier Ltd.
  • Article
    Citation - WoS: 66
    Citation - Scopus: 85
    Removal of Ammonium and Phosphate From the Supernatant of Anaerobically Digested Waste Activated Sludge by Chemical Precipitation
    (Elsevier Sci Ltd, 2009) Uludag-Demirer, Sibel; Othman, Maazuza
    The removal of ammonium (NH4+) and phosphate (PO43-) from supernatant of anaerobic digestion by magnesium ammonium phosphate (MAP) formation was Studied. To be able to find out the loss of NH4+ by its transformation to NH3, rates of NH4+ removal by aeration and by MAP formation combined with aeration were compared. NH4+ removal by aeration was found to be insignificant. The kinetics of MAP formation was fast. The removal rate of NH4+ and Mg2+ was the smallest and the largest, respectively based on rate constants calculated. The removal of NH4+ showed sensitivity to Mg2+ and PO43- concentrations and controlled the purity of MAP precipitate. The removal of PO43- was found to be Sensitive to mainly Mg2+ ion. These results also indicated that as the supernatant Solution became more saturated in terms of MAP forming ions, the effect of pH increase became insignificant in the removal of ions from the solution. (C) 2009 Elsevier Ltd. All rights reserved.
  • Article
    Citation - WoS: 2
    Citation - Scopus: 3
    Effects of Privatization: a Case Study From Cayirhan Coal District, Turkey
    (Elsevier Sci Ltd, 2006) Eyyuboglu, E. Mustafa
    Privatization of lignite coal-fired power plants in Turkey began in the middle of 1990 and is still an ongoing process. Among the 10 power plants offered to bidders in 1996, only Cayirhan power plant bundled with the coal mine was privatized. Considerable improvements have been obtained following the privatization of both the power plant and the coal mine. In view of its success, it is considered that Cayirhan experience could serve as a model for further privatization in energy sector, planned to be completed by the end of 2006 according to the agenda issued by government. This paper deals with the overall improvements following the privatization of both the power plant and the coal mine. In particular, mechanized roadway drivage performances before and after privatization are compared in order to highlight the specific effects of privatization in this area. It is found that competition, organizational and operational changes are the main causes of improvements attained in the post-privatization period. (c) 2005 Elsevier Ltd. All rights reserved.