Browsing by Author "Oncel S.S."
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Item Comparison of different photobioreactor configurations and empirical computational fluid dynamics simulation for fucoxanthin production(Elsevier B.V., 2019) Aslanbay Guler B.; Deniz I.; Demirel Z.; Oncel S.S.; Imamoglu E.Microalgae production in culture systems has been a topic of intense study for a long time. Optimization of cultivation conditions and design parameters of photobioreactors are essential for the development of economically and technically feasible algae technologies. The present study aimed to evaluate the effect of different photobioreactor (PBR) configurations on biomass and fucoxanthin production from Phaeodactylum tricornutum and to examine culture conditions by using Computational Fluid Dynamics (CFD) simulation for the photobioreactor having the maximum yield. The cells were first cultivated in three different PBRs (flat plate, airlift and stirred tank) and the maximum cell concentration of 5.94 ± 0.12 × 107 cells/ml was obtained in flat plate PBR. Also, highest fucoxanthin amount was found in the same PBR with the value of 2.43 ± 0.23 mg g−1. Flat plate PBR was simulated using CFD and the obtained results were used to evaluate mixing efficiency, flow dynamics and velocity fields. The extent of mixing was found sufficient to achieve homogenous culture medium and mean turbulent kinetic energy field suggested a homogeneous dissipation, also higher intensities of turbulence were observed around the nozzles and at the liquid-gas interphase. However, dead zones and vortex formations were observed in a small proportion of PBR. For further researches, assembling mixers or baffles into the PBR may be a feasible and effective method to improve the mixing efficiency and to prevent hydrodynamic problems. It was shown that the result of cultivation experiment had good agreement with that of CFD prediction. © 2018 Elsevier B.V.Item Transition from start-up to scale-up for fucoxanthin production in flat plate photobioreactor(Springer Netherlands, 2019) Aslanbay Guler B.; Deniz I.; Demirel Z.; Oncel S.S.; Imamoglu E.Fucoxanthin is one of the most important carotenoids and is found in diatoms such as Phaeodactylum tricornutum. The aim of this study was to evaluate the use of both the constant volumetric power consumption rate as scale-up strategy and the constant light energy per unit volume for transition from 1000-mL bottle to 2-L and 7-L flat plate photobioreactors for fucoxanthin production in P. tricornutum, considering whether an increase in the fucoxanthin yield could be achieved. The cell concentration and fucoxanthin content were enhanced with increasing the cultivation volume. It was found that the fucoxanthin yield increased 2.3 times in 2-L photobioreactor and 2.6 times in 7-L photobioreactor in comparison to the value of 1.05 mg g−1 dry weight in the cultivation bottle. Consequently, fucoxanthin production was successfully step-wise scaled-up from 1000-mL bottle to 7-L photobioreactor using both constant volumetric power consumption rate and the constant light energy per unit volume under laboratory conditions. © 2019, Springer Nature B.V.Item Computational fluid dynamics modelling of stirred tank photobioreactor for Haematococcus pluvialis production: Hydrodynamics and mixing conditions(Elsevier B.V., 2020) Aslanbay Guler B.; Deniz I.; Demirel Z.; Oncel S.S.; Imamoglu E.Agitated photobioreactors (PBR) have been widespread for the cultivation of microalgae because of their advantages in mixing and mass transfer conditions. However, it is difficult to investigate the behaviors of cultivation broth flow with experimental procedures in these PBRs. Computational Fluid Dynamics (CFD) is a common method that has been used to simulate the performance of fluid containing systems in order to investigate the fluid flow, reduce the design cost and improve the efficiency. The objective of this study was to evaluate hydrodynamics and mixing conditions of stirred tank PBR for Haematococcus pluvialis production experimentally and numerically. The cells were first cultivated in a stirred tank PBR containing Rushton turbine impeller and the cell growth was examined during 10 days. At the end of cultivation, the cell concentration was reached the value of 3.1 ± 0.1 × 105 cells mL−1 with the total carotenoid content of 2.47 ± 0.01 mg L−1. Then, the hydrodynamic analyses were conducted to evaluate the average velocity magnitude, turbulence properties and dead zone inside the PBR. The simulation results obtained from realizable k-ε turbulence model showed that the uniformity index of average velocity was found as 0.86. This result showed that the fluid flow showed similar behavior in the most parts of PBR except around the impellers. The velocity contours supported that the mixing conditions were supplied efficiently, however the vortex formation was observed around the impellers in spite of the baffles. In addition, the turbulence kinetic energy having a vital influence on mixing characteristics was found between the values of 1.0 × 10−2 and 3.0 × 10−2 m2 s−2 and the lowest values were observed between two impellers due to extent of mixing. Obtained results could be used to re-design PBR configurations considering the impeller type, the distance between impellers and cultivation conditions. © 2020 Elsevier B.V.Item Effect of Agitation and Aeration on Keratinase Production in Bioreactors Using Bioprocess Engineering Aspects(Springer, 2021) Deniz I.; Demir T.; Oncel S.S.; Hames E.E.; Vardar-Sukan F.Streptomyces sp. 2M21 was evaluated for keratinase production in bioreactors using chicken feathers. Firstly, optimization of bioengineering parameters (agitation and aeration rates) using Response Surface Methodology was carried out in 2 L bioreactors. Optimized conditions identified by the modified quadratic model were verified as 150 rpm and 1 vvm experimentally corresponding to 351 U/ml of keratinase activity. Moreover, scaling up sequentially to 20 L bioreactors was implemented using constant impeller tip speed and constant mass transfer coefficient as key scale-up parameters. The keratinase activity in 5, 10 and 20 L bioreactors showed similar results with the one of shake flasks (412 U/ml) and 2 L bioreactors (351 U/ml)with respect to the keratinase activity values of 336, 385 and 344 U/ml, respectively. The results suggest keratinase production by evaluating chicken feathers in commercial level. Furthermore, this study has potential to contribute industrial scale production of keratinase by Streptomyces sp. 2M21 using the proposed bioreactor conditions. © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.Item Photobioreactors as potential tools for environmentally friendly and sustainable buildings(Springer Science and Business Media Deutschland GmbH, 2022) Inam A.; Oncel S.S.Global warming is a critical risk for the balance of nature, and its effects are increasing due to gases like CO2. One approach for CO2 capture is bringing together microalgae and buildings in esthetic bio-façade systems for obtaining environmentally friendly benefits. The aim of this study is to investigate the microalgae photobioreactors (PBR) as a potential bio-façade unit. Bio-façade concept focused on the multiple uses of water and nutrients, as well as CO2 capture, to highlight the sustainability and practicality. Chlorella vulgaris is selected as a model microalga due to its low doubling time and high biomass productivity. Experiments covered the dilutions of microalga medium (10%, 20%, 40%, 80%), recycling the cell separated medium and addition of CO2-enriched air (5% and 10%) focusing on their effects on various key factors like biomass and photosynthetic activity. PBR integrated laboratory scale house unit has also been constructed lastly. According to the preliminary results, up to 80% dilution, up to three cycles of medium and 5% CO2-enriched environment provided the high level of activity for bio-façade system. Interior air quality, changing of temperature and amounts of CO2–O2 with increasing of the biomass were investigated in PBR integrated laboratory scale house unit which depended on the outcomes of preliminary experiments (20% dilution and 5% CO2-enriched air). The results of unit showed the positive effects of the microalga integration with regards to its capability as a biofilter and a biocurtain for the sustainability. Graphic abstract: [Figure not available: see fulltext.] © 2021, Islamic Azad University (IAU).Item Microalgae pigments as a sustainable approach to textile dyeing: A critical review(Elsevier B.V., 2023) Mutaf-Kılıc T.; Demir A.; Elibol M.; Oncel S.S.Microalgae derived pigments, such as phycobiliproteins, chlorophylls, and carotenoids, offer eco-friendly alternatives to synthetic dyes. These pigments are known for their vibrant colors, as well as their antimicrobial, antioxidative, and UV protective properties, making them commonly used in the food, pharmaceutical, and cosmetic industries. Recently, they have also gained attention in the textile dyeing industry. Compared to other natural dye sources like plants, bacteria, and fungi, microalgae pigments possess significant potential as natural textile dyes. They exhibit high pigment productivity, more sustainable production systems, current industrial-scale production, and a lack of seasonal dependency. This review aims to provide an overview of the current state, limitations, and future prospects regarding the utilization of microalgae pigments as textile dyes. The report emphasizes the commercial availability of microalgae pigments, highlights current studies exploring their dyeing potential on various textile materials, and discusses the development techniques aimed at enhancing dyeing performance. This emerging and promising research field has the potential to revolutionize the production of eco-friendly and sustainable textile products, while also contributing to a reduction in the use of synthetic dyes in the textile industry. © 2023 Elsevier B.V.Item Bubble column and airlift bioreactor systems for animal cell culture applications(John Wiley and Sons Ltd, 2023) Mutaf T.; Oncel S.S.Many biopharmaceutical industries have focused on the screening for novel cell lines and producers for manufacturing of advanced therapeutics. Commercial scale productions at reduced cost and improved productivity are only possible with the bioreactor systems. Animal cell culture bioreactors have all started to draw attention in view that 20th century and advanced significantly over the previous few a long time especially with the need for viral vaccine productions, monoclonal antibody productions and in vitro meat productions. To produce these high value-added products in large scales, bioreactor configurations are advanced to reduce investment and operational costs, control the process parameters, enhance productivity, and make easier scale-up. Although novel bioreactor systems have interested in recent years, conventional bubble column and airlift systems are still the most familiar and experienced bioreactors. Pneumatically agitated bioreactors have been studied for many years in animal cell culture. This current review intends to provide an overview of pneumatic bioreactor productions for animal cell culture applications in key items of cell culture and bioreactor technology, for example, design parameters, transport phenomena during cultivation, shear sensitivity of cells. Besides, the previous studies, investigated that the design parameters and process conditions for productivity and shear sensitivity, have been reviewed and summarized. © 2022 Curtin University and John Wiley & Sons Ltd.