Person: KAZAN, DİLEK
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KAZAN
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DİLEK
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Publication Metadata only Techno-economic analysis of caffeine and catechins production from black tea waste(ELSEVIER, 2019) SARIYAR AKBULUT, BERNA; Sayar, Nihat Alpagu; Sam, Selcen Durmaz; Pinar, Orkun; Serper, Damla; Akbulut, Berna Sanyar; Kazan, Dilek; Sayar, Ahmet Alpy This work establishes a proof of concept level economic assessment of a novel commercial production scheme for caffeine and catechins from black tea waste collected in the north-eastern region of Turkey. A base case in which dichloromethane (DCM) is used as the product extracting agent and an alternative greener case where DCM is replaced with environmentally friendlier ethyl acetate (EA) were designed and modelled on Superpro Designer platform. Profitability analyses were conducted for both cases, each treating 30,000 MT/year of black tea waste. Under the base case scenario, the Net Present Value (NPV) was calculated as 16,249,000 USD whereas the alternative scenario gave an NPV of 4,379,000 USD with corresponding payback times of 5.64 and 6.79 years. A novel techno-economic evaluation method involving the metamodeling of Superpro Designer models via Kriging and subsequent multi-objective optimization is incorporated into the economic assessment and applied to the two cases in order to optimize selected dominant process variables. Optimal values for dominant operating process variables were found using 3-D graphs simulating the combined effects of these variables on NPV. Results showed that the base case has a greater potentiality to generate profit. However, the greener case could be implemented if it is supported on environmental and toxicity issues considering the potential health and pollution preventive benefits. The present work demonstrates how the integration of novel conceptual design, modelling, and optimization approaches can foster broader evaluation of bioprocesses utilizing negative-value agro-wastes for the production of value-added chemicals. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.Publication Metadata only Assessment of different carbon and salinity level on growth kinetics, lipid, and starch composition of Chlorella vulgaris SAG 211-12(TAYLOR & FRANCIS INC, 2020) SAYAR, AHMET ALP; Kaplan, Ecem; Sayar, Nihat Alpagu; Kazan, Dilek; Sayar, Ahmet AlpThe quality of microalgal biofuel depends on the fatty acid (FA) distribution. A high ratio of saturated fatty acids (SFAs) favors better biofuel characteristics. Palmitic acid (C16:0) and stearic acid (C18:0) are essential FAs for required biodiesel quality. In this study, combined effects of growth medium concentrations of NaCl, glucose and glycerol on cell composition and FA profile of the Chlorella vulgaris SAG 211-12 were investigated. A central composite design (CCD) based design of experiments (DoE) was used for experimental setup. According to experimental results, the maximum mass fraction for palmitic acid (C16:0), 40.67% of total fatty acids, was obtained in the medium supplemented with 0.9% (w/v) NaCl, 0.3% (w/v) glucose, and 0.3% (w/v) glycerol, whereas stearic acid (C18:0) percentage reached the highest value of 22.16% of total fatty acids in the presence of 2.5% NaCl, 0.6% glucose, and 0.6% glycerol. According to the same set of designed experiments, best starch content was found as 22.08% of dry cell weight in a medium containing 2.0% NaCl, 0.3% glucose, and 0.3% glycerol. C16:0 mass fraction as a function of three medium ingredient concentrations was modeled using a Kriging model. Optimum concentrations of NaCl, glucose and glycerol to reach maximum C16:0 fraction were predicted as 0.5, 1, and 1%, respectively.Publication Metadata only Bioethanol Production From Turkish Hazelnut Husk Process Design and Economic Evaluation(SPRINGER, 2019) SAYAR, AHMET ALP; Sayar, Nihat Alpagu; Pinar, Orkun; Kazan, Dilek; Sayar, Ahmet AlpThe main objective of the current study is to develop and assess the preliminary synthetic design steps of an innovative and unprecedented bioprocess plant converting Turkish hazelnut husk into lignocellulosic ethanol with an emphasis on economic evaluation. Valorization of this agricultural waste would provide a promising economic potential and long-term sustainability with acceptable environmental impact. Preliminary economic evaluations are performed on several scenarios where the effects of changing various process design and operational inputs such as designed plant capacity, evaporation unit operation efficiency, and biocatalyst and nitrogen source prices are simulated. The total capital investment for the base case scenario with an annual throughput of 180,000 metric tons (MT) hazelnut husk is just above USD 111million. The annual operational costs for this case amount to USD 61million. Assuming a sales price of USD 1.50 per kg of bioethanol (achieved via governmental subsidy and tax incentives) the return on investment of the project comes to 12.61% with a 8year payback period. An uncertainty analysis performed on the annual hazelnut husk availability and biocatalyst and nitrogen source price fluctuations establishes a basis for further design of the process taking into account the risk factors associated with the project. The case studies and the uncertainty analysis confirm the fact that production of second generation bioethanol from hazelnut husk in Turkey is a worthwhile endeavor with an economic potential especially with additional social and environmental advantages.Publication Metadata only A Maltooligosaccharides Producing alpha-Amylase from Bacillus subtilis SDP1 Isolated from Rhizosphere of Acacia cyanophylla Lindley(TAYLOR & FRANCIS INC, 2014) OGAN, AYŞE; Ozturk, Hasan Umit; Denizci, Aziz Akin; Ogan, Ayse; Kazan, DilekMaltooligosaccharides producing amylases are required in the food industry, especially in breadmaking. The Bacillus subtilis strain SDP1 amylase hydrolyses starch to produce maltotriose and maltotetraose along with maltose after prolonged reactions of 5 h. Bacillus subtilis strain SDP1 was isolated from the rhizosphere of Acacia cyanophylla Lindley from the cukurova region of Turkey. The highest enzyme production was achieved with soluble starch as the carbon and yeast extract as the nitrogen source and at pH 7.0 and 37 degrees C. Under optimized culture conditions, 68.49 U/mL activity was obtained. SDP1 alpha-amylase had molecular weight of 61 kD. The optimum pH of the enzyme was 7.0 and was highly active at pH ranging from 5.0 to 9.0. The optimum temperature of the crude enzyme was 60 degrees C, and it retained 83% and 74% of its initial activity after 1 h and 2 h incubation periods, respectively, at 50 degrees C. While, Mn+2 has a stimulatory effect on the activity, Ca+2, Mg+2, Na+ did not effect the enzyme activity. Fe+3, Ni+2, Cu+2 and Co+2 had an inhibitory effect on SDP1 amylase activity.