Production of microalgae in photobioreactor and characterization of algal fatty acids for biodiesel feedstock

• Main Author: Anh, Hoang Hoang
• Format: text
• Language: English
• Published: Animo Repository 2010
• Subjects: Microalgae; Photobioreactors; Algal biofuels; Fatty acids; Chemical Engineering
• Online Access: https://animorepository.dlsu.edu.ph/etd_masteral/6136; https://animorepository.dlsu.edu.ph/context/etd_masteral/article/13167/viewcontent/CDTG004813_P.pdf
• Institution: De La Salle University

Biodiesel from microalgae is a good candidate to solve the problem of dwindling fossil fuel resources satisfying both alternative fuel requirement and the problem of the competition for food and biofuel production. In this study, growth patterns of three microalgae such as Navicula sp., Amphora sp. and Chlorella sorokiniana in photobioreactors were evaluated using COD measurement method. In order to prepare biodiesel samples from limited amounts of biomass derived from algal culture in flask photobioreactor, direct transesterification from wet biomass was applied. The GC-FID analysis showed that dominant fatty acid components of two marine species Amphora sp. and Navicula sp. were palmitic acid (C16:0), oleic acid (C18:1) and linoleic acid (C18:2). The predominant components of the freshwater species C. sorokiniana were linoleic acid (C18:2) and linolenic acid (C18:3). Estimated from the fatty acid profiles, the cetane numbers of biodiesel samples produced from Amphora sp., Navicula sp. and C. sorokiniana were 62.65, 63.61 and 47.02, respectively. Similarly, the iodine numbers were 90.808, 85.807 and 152.904. Taguchi orthogonal array of L934 was applied to determine the optimum combination of operating parameters that maximized oil yield (mg/L/day), oil to biomass COD ratio and biomass COD production rate of a combined flask-flat plate photobioreactors. This array has nine runs and four factors with three levels. The four factors considered were photoperiod, light intensity, CO2 flow rate and algal strain. The three levels that were chosen for each factor were as follows (8:16, 12:12 and 24:0) (hrs) for photoperiod, (309, 590 and 784) (lux) for light intensity, (0, 0.5 and 1.0) (L/ min) for CO2 flow rate and (Navicula sp., Amphora sp., and Chlorella sorokiniana) for algal strain. The result revealed that the optimum conditions were found to be 24 light hours of the photoperiod, 784 lux of light intensity, 0.5 L/min of CO2 flow rate and algal strain Navicula sp. Applying these conditions in the confirmation run, the maximum oil yield reached 13.9 (mg/L/day), the oil to biomass COD ratio reached 8.73 (mg oil/ 100 mg biomass COD) and the biomass COD production rate was 159.098 (mg/L/day). In terms of the oil yield, the maximum value for Amphora sp. was 5.016 (mg/L/day) and this value for C.sorokiniana was 4.77 (mg/L/day)