Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 2Citation - Scopus: 1Dynamics of Co2 Consumption, and Biomass and Lipid Carbon Production During Photobioreactor Cultivation of the Diatom Cyclotella(TÜBİTAK - Türkiye Bilimsel ve Teknolojik Araştırma Kurumu, 2023) Ökten, HaticeUnderstanding of CO2 delivery and consumption dynamics in algal photobioreactors are critical to unravel microalgae’s full potential for bioproduct generation and carbon capture from flue gas streams. This study aims to expand our current understanding by cultivating the diatom Cyclotella under controlled process conditions of a bubble column photobioreactor and analyzing CO2 consumption dynamics in real time using results from an online CO2 sensor connected to the reactor exhaust. Two sets of experiments were conducted: they served to contrast the influence of silicon and nitrate (Si&N colimitation) and Si limitation, and the light availability, respectively. CO2 consumption was calculated based on the mass balance around the reactor inlet and outlet gas streams. Biomass samples and lipid extracts were analyzed for carbon (C) content to determine biomass-C and lipid-C concentrations. The outlet CO2 concentrations varied significantly with cultivation time and process conditions. More than 15% to 65% of the CO2 introduced left the reactor in the exhaust at any instance based on the set CO2 transfer rates. The highest average daily capturing efficiency was 60%. Nutrient limitation regimes imposed generated unique CO2 consumption profiles undiscernible by the biomass-C analysis, i.e. unlike Si limitation, N limitation had more immediate detrimental effects on C consumption. Final biomass-C concentration increased with increasing N and light availability, 275 mg/L vs. 336 mg/L, and 270 mg/L vs. 501 mg/L, respectively. Biomass-C based capturing efficiency approximations resulted in 20% to 40% underestimation. Under Si-limited conditions, the higher light intensity increased the final lipid-C to biomass-C ratio by two times (from 20% to 40%) and the final lipid-C concentration and peak productivity by four times (from 56 mg/L to 216 mg/L, from 7 to 30 mg/L-day, respectively). This study demonstrates online exhaust CO2 concentration-based analysis’s unique capabilities for assessing carbon availability and capture, organic-C production, and its diversion to biomass and lipid production.Article Citation - WoS: 2Citation - Scopus: 2Evaluating the Performance of Conventional Daf and Posidaf Processes for Cyanobacteria Separation at a Pilot Plant Scale(IWA Publishing, 2022) Yap, Russell K.L.; Rao, N. R.H.; Holmes, M.; Whittaker, Michael; Stuetz, Richard M.; Jefferson, Bruce; Bulmuş, Volga; Peirson, William Leslie; Henderson, R. K.In this work, a commercially available water treatment polymer poly(N,N-diallyl-N,N-dimethylammonium chloride) (PDADMAC) and a hydrophobically modified polymer (HMP) designed to adhere to bubble surfaces were applied for the first time in the novel Posi-dissolved air flotation process (PosiDAF) that uses polymer-modified bubbles, at pilot-scale for the treatment of waste stabilisation pond samples rich in algae. It was found that PDADMAC in PosiDAF gave comparable removal to that achieved using conventional DAF at .95% cell separation. Furthermore, the float layer was more uniform and thicker with up to 8% solid contents compared to conventional DAF, which comprised discrete floc clusters with an average solid concentration of ∼4.1%. In contrast to the use of PDADMAC, the application of the HMP did not achieve similarly good separation at pilot scale. It was hypothesised that this may be due to the micellisation of the HMP on the bubble surface, creating unstable bubbles that coalesced and prevented polymer-bubble-cell interactions, which are crucial for effective cell separation. On comparison of the costs of PosiDAF and conventional DAF, it was found that PosiDAF resulted in cost-savings of up to 74% due to low chemical consumption. In summary, PosiDAF reduced chemical cost and increased solid contents in the metal-free float.