Removal of suspended particles from extract of tuna spleen by microfiltration: Experimental evaluation of a low fouling condition

A batch concentration microfiltration with a hollow fiber membrane (pore size of 0.10 μm) was successfully employed as a pretreatment process to remove suspended particles from extract of yellowfin tuna spleen before recovery of proteases by ultafiltration. It was found that all visible suspended particles and more than half amount of soluble proteins were rejected. The transmission was about 0.8 and 0.6 for trypsin and chymotrypsin, respectively. A clear permeate with slightly yellow colour was obtained. Based on critical ratio of permeate flux (J) to wall shear stress (τ_w), the condition for sustainable operation with low fouling was experimentally evaluated. An empirical model of relation between critical J/τ_w and volume concentration factor (VCF) was found as J/τ_w = 3.29(VCF)^-0.74 at a given transmembrane pressure of 0.15 bar. The equation indicated a condition, below which there is no marked fouling and above which sharp increase of fouling could occur. The present study revealed a simple method to predict low fouling condition in batch concentration operation during membrane separation process.