Orifice-based membrane fouling inhibition employing in-situ turbulence for efficient microalgae harvesting

Abstract

In this study, a simple way of generating turbulence via the use of an orifice was developed for the purpose to mitigating membrane fouling in microalgae harvesting. When an orifice with given number of holes was installed at the inlet of a membrane module, vigorous turbulence was observed on the surface of the membrane, which caused to detach the cake layer and limit further formation of it. Experiments on Chlorella sp. HS-2 showed that the filtration efficiency increased up to 299% compared to the conventional cross-flow operation. Through computational fluid dynamics, it was proven that the orifice increased the shear stress over the membrane surface area from 0.7 Pa to maximum average shear stress of 52.3 Pa. With regards to the operation time, microalgae harvesting could be finished nearly 3 times faster with the orifice. Faster harvesting time implies more quantity at a given time, not to mention prevention of quality degradation associated with cell decay. Low power consumption with enhanced filtration performance supported that membrane filtration equipped with an orifice can offer a promising means for microalgae harvesting, in terms of surpassing effectiveness and simplicity.