Characterization of Microalgae for the Purpose of Biofuel Production

Abstract. It is now widely accepted that microalgae are promising candidate feedstocks for biofuel production, especially for biodiesel. Microalgae consist of a vast number of species that contain complex chemical constituents and physical structures. The purpose of this study is to understand the physical and chemical properties of selected microalgae, which is critical to the design of appropriate processes for commercial biofuel production. ASTM standard methods were implemented to examine the microalgae properties, including proximate and ultimate analyses. Among the microalgae studied, green microalgae have more volatile matter than brown microalgae, while the latter contain much higher ash content (as high as 43.4%wt ±0.20%wt dry basis). The lowest ash content was found in the samples of green microalgae (14.3%wt ±0.10%wt dry basis). Ultimate analysis showed that brown microalgae have less carbon content (approx. 25%wt dry basis) as compared to green microalgae (49%wt to 58%wt dry basis). All samples of microalgae were high in sulfur content (0.4%wt to 1.0%wt dry basis). Mineral contents of all microalgal samples were similar to those commonly present in other biomass. Brown microalgae contain significantly higher amounts of carbohydrates (72.9%wt to 75.5%wt dry basis) than green microalgae. On the other hand, green microalgae contain more crude fat (17.1%wt to 27.8%wt dry basis) than brown microalgae. The fatty acid profiles show that the primary fatty acids in microalgal lipids are similar to those of vegetable oils such as soybean oil. However, there are also many odd-numbered fatty acids, such as C15:0, C17:0, and C19:0, which are not typically seen in other seed oils.