Browsing by Author "Keskin, Tugba"

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Application of Various Microalgal Species for Lipid Production: Biotechnological and Engineering Aspects
(Springer Heidelberg, 2026) Habashy, Mahmoud M.; Li, Lu; Angulo-Mosquera, Lina S.; Bayar, Busra; Abubackar, Haris Nalakath; Keskin, Tugba; Rene, Eldon R.
Lipids derived from algal biomass are important constituents of biofuels, nutraceuticals, cosmeceuticals, and animal feed, inter alia. This necessitates the identification and large-scale production of microalgal species that can serve as the biomass based raw material for the above-mentioned categories of bio-products. In this vein, this review sifts through the literature and describes the most promising microalgal species that synthesize lipids and, when subjected to specific conditions, show enhanced lipid production. Currently, Chlorella sp., Cyclotella sp., Neochloris oleoabundans, and Isochrysis galbana are the species with the highest lipid contents. The review mentions and discusses various bioreactor configurations that can be used for large-scale culturing of these microalgae in a comparative aspect. Various configurations of photobioreactors are suitable for high biomass and lipid productivity. Further, prominent strategies of lipid extraction from microalgae have been elaborated, from conventional techniques to the latest ones, comparing and contrasting their advantages and disadvantages. While solvent-based extractions may have their advantages, it would be prudent to explore more eco-friendly techniques for scale-up. Lastly, the review gives a comprehensive account of the biorefinery approach to culturing microalgae, emphasising the assessment of their economic performance using different software and models, such as the techno-economic assessment model. The application of tools such as multi-criteria decision analysis that assess energy technology could enable better optimization. Microalgae have the potential to be used as a renewable source of fuel and feed; therefore, it is incumbent on the scientific community to significantly reduce production costs while ensuring sustainability.
Citation - WoS: 2
Citation - Scopus: 3
Bioethanol Production From C1 Gases Using Alternative Media by Syngas Fermentation
(Inderscience Enterprises Ltd, 2022) Gungormusler, Mine; Azbar, Nuri; Keskin, Tugba
The main aim of the present study was to evaluate the effects of the presence or absence of trace elements and yeast extract on growth and ethanol production by Clostridium ragsdalei grown on C1 gas dominated syngas (60% CO, 10% CO2, 10% CH4, 10% H-2, 10% N-2). Comparison of whey powder and glucose syrup as low-cost substitutes helped develop a more cost-effective medium formulation to produce ethanol from syngas with significantly higher yields, achieving up to a 3.8-fold improvement with co-utilisation of syngas and glucose syrup. In addition, the results provided further insights into medium manipulation and possible modifications to decrease total costs for increased ethanol production by solventogenic acetogens via syngas fermentation by achieving a 15.6% reduction in the cost of fermentation medium.
Bioethanol Production from C1 Gases Using Alternative Media by Syngas Fermentation
(Inderscience Publishers, 2022) Keskin, Tugba; Azbar, Nuri; Gungormusler, Mine
Citation - WoS: 19
Citation - Scopus: 22
Bioprocesses for Resource Recovery From Waste Gases: Current Trends and Industrial Applications
(Pergamon-Elsevier Science Ltd, 2022) Khanongnuch, Ramita; Abubackar, Harris Nalakath; Keskin, Tugba; Gungormusler, Mine; Duman, Gozde; Aggarwal, Ayushi; Behera, Shisir Kumar; Rene, Eldon R.
Air pollution is a topic of important global concern because it has contributed significantly to an increase in the earth's global warming potential and contributed to severe health and environmental impacts. In this review, the different bioreactor configurations commonly used for waste gas treatment, namely the biofilters, the bio-trickling filters and the bioscrubbers, and their industrial applications were compared in terms of the type of inoculum, the packing material/media, removal efficiency and elimination capacity. Typically, biofilters are operated under the following range of operating conditions: gas residence time = 15-60 s; gas flow rate = 50-300,000 m(3) h(-1); temperature = 15-30 ?degrees C; pH = 6.0-7.5; filter area = 100-3000 m(2); relative humidity > 95.0%; and removal efficiencies > 75.0% depending on the waste gas composition and concentration. The biotechnological approaches for resource recovery, i.e., the conversion of C1 gaseous compounds (CO, CO2 and CH4) to liquified value-added products or biofuels have been discussed. From this review, it was evident that the performances of different aerobic, anoxic and/or anaerobic lab, pilot and full-scale bioreactors for waste gas treatment and resource recovery depend on the composition, the individual concentration of pollutants present in the waste gas and the gas flow rate. Although most of the research on product recovery from waste gas is rather limited to lab/pilot-scale studies, there are some key commercialized technologies that have proven to be economical at the full-scale. Thus, this review, comprehensively presents a complete overview of the current trends and limitations of conventional waste gas treatment systems, the benefits of novel bioreactor configura-tions and their potential to be applied for resource recovery from waste gases.