Strategies for enhanced biomass and lipid production by Chlorella pyrenoidosa culture in starch processing wastewater

Abstract

Starch wastewater contains various nutrients, as a potential medium for cultivating microalgae. In this study, strategies including wastewater treatments and mixing were investigated to enhance biomass and lipid production. The microalgae C hlorella pyrenoidosa performed normal growth in anaerobic digested and secondary treated starch wastewater. However, their lipid yields were very low (6.7–22.9 mg L −1 ·d −1 ) due to the low biomass production or lipid content. Therefore, the strategy for mixing different treatment stages of starch wastewater was tested to improve algal growth and lipid accumulation. In comparison to blank culture, adding 50% acidified starch wastewater into anaerobic and secondary treated starch wastewater significantly increased biomass concentration by 78.1% (to 3.3 g L −1 ) and 105.2% (to 1.2 g L −1 ), while achieving higher lipid content to 18.7–28.0%. Moreover, the mixed culture improved the degree of saturated fatty acids (typically in palmitic and stearic acid). This provides a promising approach to improve algal lipid yield and quality using starch wastewater. • Microalgae culture using different treatment stages of starch wastewater. • Mixing different starch wastewater significantly enhanced biomass production. • Wastewater mixing improved the cellular lipid content and saturation degree.