Harvesting of Scenedesmus obliquus using dynamic filtration with a perforated disk

Abstract

Dynamic filtration adopting the rotation of a perforated disk was applied to harvest Scenedesmus obliquus. The highest rotation speed of the disk was found to give rise to 464 and 454 L/m2/h of plateau permeate flux for microfiltration (MF) membrane and ultrafiltration (UF) membrane, respectively, which were approximately 9 and 11 times higher than those with no rotation. This marked performance improvement for both filtration methods, with the UF exhibiting lower irreversible fouling, was attributed to the reduction of not only cake fouling (up to 97%) but also adsorption fouling (up to 71%) by way of high shear stress on the membrane surface. At the high rotation speed in which fouling was effectively suppressed, flux was linearly increased by trans-membrane pressure; at low speeds where fouling formation remained less disrupted, on the other hand, it reached a certain limit. Besides, fouling built and worsened particularly by high amounts of extracellular polymeric substance (EPS), which was as in the case of the seawater-supplemented culture, was effectively alleviated by fast rotation. The dynamic UF based on the rotation of the perforated disk was indeed a promising and suited means of harvesting S. obliquus, especially cells grown under economical yet EPS-inducing cultivation conditions.