Enhancement of microalgal consortium cultivation efficiency using carbon dioxide for biomass and lipid production

การเพิ่มประสิทธิภาพการเพาะเลี้ยงกลุ่มสาหร่ายขนาดเล็กโดยการใช้ก๊าซคาร์บอนไดออกไซด์เพื่อผลิตชีวมวลและลิพิด

Name: Sunisa Boonma

ThaSH: Microalgae -- Biotechnology

Classification :.DDC: 579.8

ThaSH: Microalgae

ThaSH: Cultures (Biology)

ThaSH: Carbon dioxide

ThaSH: Biomass

Abstract: Carbon dioxide (CO2) is one of the main greenhouse gases that traps heat in the atmosphere and contributes to global warming. Among the various methods being proposed to reduce CO2 emissions, the biological CO2 sequestration using phototropic microalgae has received widespread attention in recent years. Through biological CO2 sequestration, CO2 can be fixed and converted into biomass and lipids. These algal lipids could then be used as feedstock for biodiesel production. In this study, the cultivation of a microalgal consortium (MC) using CO2 were done on the laboratory scale and in the outdoor open system. In the laboratory experiment, the MC was cultivated with different aerations: non-aeration (control), normal air (0.03% CO2) and 10% CO2 at flow rate of 0.2 vvm. It was found that the growth of microalgae under 10% CO2 aeration was higher than those of the other conditions. Next, the effects of CO2 concentrations (0.03%-30% v/v CO2) on algal biomass, lipid production, and CO2 fixation were investigated. It was found that the MC could grow well under 10% and 30% CO2 supplementation. The biomass concentration and lipid content of the culture supplemented with 30% CO2 was the highest among all the specimens with 0.31+0.17 g L-1 and 27.6+0.68% of dry weight, respectively. The CO2 fixation rate that was recorded at under 30% CO2 supplementation was increased 6-fold when compared with ambient air (0.03% CO2). The common algal species found in this supplement were green microalgae, specifically Acutodesmus obliguus (Turpin) Kützing, Chlamydomonas crassa H.R. Christen, Dictyosphaerium granulatum Hindák and Chlorella vulgaris Beyerinck [Beijerinck]. Next, the effects of the CO2 aeration rate on the CO2 fixation efficiency of MC were studied. The results found that an increase of the CO2 aeration rate between 0.2-1.0 vvm could lead to increased biomass concentration and the lipid content of the microalgae. The MC under 1.0 vvm CO2 aeration rate had the highest biomass concentration and the lipid content with 0.92+0.1 g L-1 and 24.45+1.03% of dry weight, respectively. The potential of CO2 fixation under 1.0 vvm CO2 aeration rate was increased 2.7-fold when compared with the 0.2 vvm CO2 aeration rate. The dominant microalgal species were C. vulgaris Beyerinck [Beijerinck], Acutodesmus dimorphus (Turpin) Tsarenko, Carteria sp. and Monoraphidium contortum (Thuret) Komárková-Legnerová. In order to study the possibility of CO2 reduction from the industrial exhaust gas and biooil production from microalgae, MC was cultivated with the exhaust gas (19% CO2) that was derived from a power generator supplied by biogas from chicken manure in an outdoor open system. It was found that the biomass concentration and lipid content of the microalgae supplemented with the exhaust gas was higher than that of the ambient air. The biomass concentration and lipid content of MC under exhaust gas condition were 0.25+0.04 g L-1 and 16.96+2.29% of dry weight, respectively. The major microalgal species found in the exhaust gas condition was Acutodesmus spp. The CO2 fixation level under exhaust gas supplementation was increased 1.3-fold when compared with the ambient air. In addition, the effects of the season and CO2 supplementation on microalgae cultivation were studied for the feasibility of large-scale biofuel production and CO2 mitigation. The MC was cultivated with pure CO2 (100% CO2) at aeration rate of 0.0002 vvm in the semi-continuous outdoor open system at Boonsom Farm during two seasons: the wet and the cold dry season. The results found that the wet and cold dry seasons showed the same trend. The recorded levels of dry weight, lipid content, carbon content and CO2 fixation rate of MC with CO2 supplement were all higher than of those without CO2 supplementation. When compare between two seasons, it found that the season had no significant effect on growth, lipid and CO2 fixation ability of microalgae. In wet season, the means of biomass concentration, lipid content and CO2 fixation rate of the MC with CO2 supplementation were 0.41+0.04 g L-1 , 17.3+0.77% of dry weight and 0.0502+0.01 g CO2 L-1 d-1 , respectively. While in the cold dry season, the means of biomass concentration, lipid content and CO2 fixation rate of the MC with CO2 supplementation were 0.43+0.04 g L-1 , 17.02+0.44% of dry weight and 0.0504+0.01 g CO2 L-1 d-1 , respectively. The dominant microalgal species observed under the CO2 supplementation condition in both two seasons were A. dimorphus (Turpin) Tsarenko, C. vulgaris Beyerinck [Beijerinck] and Nitzschia palea (Kützing) W. Smith. The major compounds of the lipids from the MC with CO2 supplementation in the wet season were palmitic acid and oleic acid. The MC showed a high potential for CO2 mitigation and should be suitable for use as a raw material in biodiesel production.

Chiang Mai University Library

Address: CHIANG MAI

Email: cmulibref@cmu.ac.th

Name: Niwooti Whangchai

Role: Chairman

Name: Yuwadee Peerapornpisal

Role: Member

Name: Suparin Chaiklangmuang

Role: Member

Name: Suraphon Chaiwongsar

Role: Member

Name: Jeeraporn Pekkoh

Role: Member

Name: Chayakorn Pumas

Role: Member

Created: 2015

Modified: 2017-09-21

Issued: 2017-09-21

วิทยานิพนธ์/Thesis

application/pdf

CallNumber: Th 579.8 S958E

eng

DegreeName: Doctor of Philosophy

Level: ปริญญาเอก

Descipline: Applied Microbiology

Grantor: มหาวิทยาลัยเชียงใหม่

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