Anti-fouling tight ultrafiltration membrane for gastrodin purification

The issues of flux decline and irreversible membrane fouling must be considered in membrane separation. In this paper, the culture medium, bacterial cells, and proteins were removed using a one-step tight ultrafiltration (UF) membrane separation process. Although the membrane resistance of the tight UF membranes increased owing to their smaller pore size, the stable flux of the 6 nm membrane during fermentation broth filtration of gastrodin was 28.0% higher than that of loose UF membranes, and the flux recovery ratio reached 97.3%. During purification, a higher filtration flux was obtained by retaining the operating pressure within the range of 2–3 bar and the operating temperature range of 50–60 °C. The average flux of a 6 nm 19-channel membrane reached 56 L·m⁻²·h⁻¹, and the total yield of gastrodin reached 96.2%. This study provides a basis for the large-scale application of tight UF membrane in food industry.