Cross-Flow Filtration of Soy Sauce Sediment with Rotating Disk Membrane Module and Agitated Disk Membrane Module

Abstract

The cross-flow micro-filtration performances of two kind of ceramic membrane modules, the rotating disk membrane module (RD module) and the agitated disk membrane module (AD module), were compared in this paper in the recovery process of soy sauce from soy sauce sediment, i.e. soy sauce sediment concentration process. Pseudo-plastic fluid characteristics of the concentrated soy sauce sediment cause a problem when the rotating is stopped suddenly by electricity failure, and so on. The RD module and AD module had lower pressure drop of the membrane modules than the conventional multi-tubular membrane module (MT module), so they could be operated at higher shear velocity under lower pressure deference across the membrane. Also, AD module had superior permeate flux to that of RD module at the same rotation rate of the rotor by the effect of both its impeller shape and the clearance between membrane and the impeller. That of RD module, however, hardly depended upon the baffle shape and the clearance between the membrane and the baffle. The permeate of AD module had good quality as soy sauce because of shorter processing time depending upon higher flux without qualitative change. The yield of soy sauce from raw soy sauce was estimated to be 99.7% by application of AD module instead of 80% of traditional process. It was concluded that AD module was the best membrane module to condense suspension from lower viscosity to higher one among the modules and other polymer membrane modules in terms of soy sauce quality, higher permeate flux, and lower pressure drop.