Endüstri Mühendisliği Bölümü

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Citation - WoS: 203
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.
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.
Citation - WoS: 49
Citation - Scopus: 54
A Profit-Oriented Mathematical Model for Hazardous Waste Locating-Routing Problem
(Elsevier Sci Ltd, 2018) Aydemir-Karadag, Ayyuce
Hazardous waste management (HWM) deals with the safe, efficient and cost effective collection, transportation, treatment and disposal of wastes. This paper presents a profit-oriented mixed integer mathematical model for the hazardous waste location-routing problem, which incorporates the energy recovery from waste and the application of the polluter pays principle. The suggested model decides on the locations and numbers of recycling, incineration, sterilization, interim storage and disposal centers and on how to transfer various types of hazardous waste and waste residues among these centers from the perspective of environmental protection. The proposed model was implemented in a real life case study and tested on various hypothetical problem instances. In addition, an extended formulation was developed on a rolling horizon basis through the objective function of Net Present Value (NPV) to analyze the overall profitability of the entire HWM system for long-term planning and a sensitivity study was conducted on different interest rates. The results show that the model is applicable to real-life waste management systems and it can provide effective solutions for large-scale HWM problems. (C) 2018 Elsevier Ltd. All rights reserved.
Citation - WoS: 64
Citation - Scopus: 84
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.
Citation - WoS: 32
Citation - Scopus: 53
A Technology Readiness Levels (Trls) Calculator Software for Systems Engineering and Technology Management Tool
(Elsevier Sci Ltd, 2010) Cakmak, Tanyel; Altunok, Taner
Turkish defense industry and policy makers seek effective and successful system development programs by implementing a validation mechanism to verify the maturity of new technologies being developed in national laboratories and industry. Technology Readiness Levels (TRLs) developed by NASA as a general metric of technology advancement and it has been widely accepted as a systems engineering and technology management metric tool. In order to explore the sufficiency of this tool, first of all, academic and applicable studies of army and civil organizations have been searched out and the lessons learned have been analyzed in this study. Thereafter, questionnaires of awareness of TRLs and TRL Calculator have been applied to defense firms in Ankara, and interviews held with the technology developers, firms' speakers and defense authorities. Finally, the applicable algorithm of TRL calculator has been recommended for Turkish defense industry. (C) 2009 Elsevier Ltd. All rights reserved.

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