Semi-continuous Cultivation of Scenedesmus quadricauda for High Biomass Production Utilizing the Byproduct Huangshui from Chinese Liquor Brewing.

Huangshui, a by-product of Chinese Liquor brewing, is rich in diverse organic compounds. In this study, the growth and biomass production of Scenedesmus quadricauda were investigated using Huangshui as culture substrate. The optimal cultivation conditions were identified as follows: pH 7.0, Huangshui concentration of 5%, cultivation duration of 6 days, and light intensity of 8000 lx. Under semi-continuous cultivation with a renewal rate of 30%, an initial cell density of 2.5 × 105 cells/mL and a renewal period of 2 days, S. quadricauda achieved a biomass concentration of 3.70 g/L and a productivity 550 mg/L-1d- 1. These values represented increases of 55.5% and 109.9%, respectively, compared to those obtained in batch culture. Notably, the protein content and protein productivity of S. quadricauda reached 49.152% and 272.78 mg/L-1d- 1, respectively, with a 38.9% increase in essential amino acid content relative to batch culture. This study appears to be the first report to cultivate microalgae in Huangshui. The Huangshui, derived from fermentation, showed considerable potential for use as a high-performance microalgae culture medium.