Carbon Dioxide Capture By The Cultivation of Microalgae Species In Different Culture Mediums Under High Co2 and Simulated Flue Gas Aeration In The Photobioreactor
Özet
Over the last century, human activities like burning fossil fuels for generating energy have changed the natural greenhouse gas balance in the atmosphere. Among greenhouse gases, the high level of carbon dioxide in the atmosphere has the most significant effect on climate change. In recent years, the biological mitigation of carbon dioxide has drawn the interest of many researchers, which would be cost-effective and environmentally friendly.The aim of this study is the assessment of carbon dioxide bioremediation rate, growth kinetics, and protein content of selected microalgae species such as Tetradesmus obliquus , Monoraphidium contortum , Psammothidium sp, and Chlorella vulgaris which are supplied with 0.04% and 10% carbon dioxide concentration in the different types of photobioreactors (PBR) (Glass bottle and tubular vertical column). This experiment showed the growth parameters for all the microalgae species significantly. increased when fed 10% carbon dioxide compared to those fed 0.04% carbon dioxide in either type of PBR. Maximum growth kinetics were observed in Chlorella vulgaris when it was grown in 10% CO2 in the tubular vertical column PBR with 2.12 g L−1 (Maximum biomass dry weight, Xmax), 0.61 g L−1 d−1 (Maximum biomass productivity, Pmax), 11.07 g d−1 (Maximum CO2 fixation rate, RC), 51.59 % (Maximum carbon content in biomass, wt. %), and 42.75 % (Overall rate of CO2 recovery in biomass, CR%). In addition, we observed a maximum protein content at Chlorella vulgaris (72.12 %) by cultivation in glass bottle PBR with 10% CO2. Among microalgae species Chlorella vulgaris sp. has been selected for the second part of the study, which has shown significant efficiency in carbon dioxide remediation in the first part. The second part of the research has been carried out in four parts: First, the use of Nano-fertilizer in the different batch culture mediums (A (Bold basal medium, BBM), B (BBM+ Nano-fertilizer), C (Nano-fertilizer+ microelements) and D (Nano-fertilizer) without aeration. Each group was divided into 5 sub-groups with the different concentration of Nano-fertilizer (for example, B1 (BBM+ 0.05 g L−1 Nano-fertilizer), B2 (BBM+ 0.06 g L−1 Nano-fertilizer), B3 (BBM+ 0.076 g L−1 Nano-fertilizer), B4 (BBM+ 0.1 g L−1 Nano-fertilizer), B5 (BBM+ 0.2 g L−1 Nano-fertilizer) which as a result, the subgroup D5 (0.2 g L−1 Nano-fertilizer) culture medium was reached to the maximum growth parameters in a shorter time (2nd day). Second, the evaluation of Chlorella vulgaris CO2 removal efficiency in the culture medium contained Nano-fertilizer by feeding with 10% CO2 in vertical column PBRs. Third, cultivation of Chlorella vulgaris in BBM+Nano-fertilizer contained culture medium under 10% CO2 aeration in the photobioreactor with different connection types. Fourth, the assessment of Chlorella vulgaris CO2 bioremediation in BBM+Nano-fertilizer contained culture medium by feeding with simulated flue gas. According to the results, the combination use of 3 g L−1 Nano-fertilizer+BBM as a culture medium has caused to reach maximum growth parameters in a short time (4th day) in comparison to the BBM (11th day). Also, the serial-connected type photobioreactors have demonstrated high efficiency in CO2 fixation rate (0.4 g L−1 d−1). Finally, by supplying the Chlorella vulgaris with simulated flue gas in 3g/l Nano-fetilizer+BBM based culture medium, the maximum CO2 bio fixation rate and overall recovery percent have been found 0.173 g L−1 d−1 and 11.80%, respectively.
