Optimization of aeration for biodiesel production by Scenedesmus obliquus grown in municipal wastewater

Abstract

Despite the significant breakthroughs in research on microalgae as a feedstock for biodiesel, its production cost is still much higher than that of fossil diesel. One possible solution to overcome this problem is to optimize algal growth and lipid production in wastewater. The present study examines the optimization of pretreatment of municipal wastewater and aeration conditions in order to enhance the lipid productivity of Scenedesmus obliquus. Results showed that no significant differences were recorded in lipid productivity of S. obliquus grown in primary settled or sterilized municipal wastewater; however, ultrasound pretreatment of wastewater significantly decreased the lipid production. Whereas, aeration rates of 0.2 vvm significantly increased lipid content by 51 %, with respect to the non-aerated culture, which resulted in maximum lipid productivity (32.5 mg L(-1) day(-1)). Furthermore, aeration enrichment by 2 % CO2 resulted in increase of lipid productivity by 46 % over the CO2 non-enriched aerated culture. Fatty acid profile showed that optimized aeration significantly enhanced monounsaturated fatty acid production, composed mainly of C18:1, by 1.8 times over the non-aerated S. obliquus culture with insignificant changes in polyunsaturated fatty acid proportion; suggesting better biodiesel characteristics for the optimized culture.

Biodiesel production potential of wastewater treatment high rate algal pond biomass

“…1. In a good agreement with the literature (Han et al, 2016), all experiments showed that 60 ± 15 wt% of total lipids (equal to 14.8 ± 4.0 wt% of ash-free biomass) was convertible to the FAMEs (raw biodiesel, i.e. mixture of desired and undesired FAMEs).…”

“…Palmitic (C16:0), palmitoleic (C16:1), stearic (C18:0), oleic (C18:1) and linolenic (C18:3) acids were predominant fatty acids in all cultures in the both CO 2 addition experiments. Despite the considerable impacts of CO 2 addition on pure culture algal lipid profile which have been reported in the literature (Han et al, 2016;Nascimento et al, 2015), slight changes in the biomass lipid profile of the WWT HRAP/HRAM biomass, illustrated ineffectiveness of CO 2 addition for improving the mixed cul- Table 5 WWT HRAM biomass fatty acid methyl esters composition (wt% of total FAMEs) over the last week of summer and winter CO 2 addition experiments. The values are mean (standard deviations) of two replications during the sampling period.…”

Recommended turbulent energy dissipation rate for biomass and lipid production of Scenedesmus obliquus in an aerated photosynthetic culture system

“…Biodiesel production is considered an alternative way to address the global energy crisis (Han et al 2016;Mu et al 2015;Yu et al 2018;Mousavi et al 2018). Microalgae are currently known to have the highest lipid production per unit area than any other plants (Qu et al 2019) and are therefore considered to be the best source of raw material for biodiesel production (Maheshwari et al 2019).…”

“…Microalgae are currently known to have the highest lipid production per unit area than any other plants (Qu et al 2019) and are therefore considered to be the best source of raw material for biodiesel production (Maheshwari et al 2019). However, the current cost of biodiesel produced using microalgae is still high (Han et al 2016), and biomass cultivation accounts for 20-30% of the total cost (Grima et al 2003). Continuous optimization of microalgae culture conditions to reduce the cultivation cost is, therefore, still an important aspect of microalgae biodiesel research.…”

Enhancement of Lipid Production of Chlorella pyrenoidosa Cultivated in Municipal Wastewater by Magnetic Treatment

“…And Han et al found that there was no significant differences in lipid productivity of S. obliquus grown in primary settled or sterilized municipal wastewater. Considering the high cost of sterilization and unfeasibility of large-scale application, pretreatment of municipal wastewater by sedimentation is a superior choice [17].…”