Nobuhiko Kanekuni

Cross-flow filtration of methane fermentation broth by ceramic membranes

Abstract With a view to concentrating the microorganisms in a thermophilic methane fermentation broth, we studied the characteristics of cross-flow filtration, using tubular ceramic membranes in liquid single-phase, gas-liquid two-phase and gas-liquid-solid three-phase flow systems. The following results were obtained: (i) an asymmetric membrane with smaller pore diameter and lower permeate resistance gave higher permeate flux, (ii) by the promotion of turbulence in the gas-liquid mixture in a two-phase flow system, the permeate flux was increased with an increase in the feed-gas flow rate, and it was of a satisfactorily high value, (iii) a cake layer was irreversibly formed on the membrane surface, behaving as a self-rejective dynamic membrane. In excessive cross-flow and/or abrasive conditions, plugging was found likely to occur because of destruction of the dynamic membrane, and the flux was lowered as a consequence, and (iv) the critical flux existed under a low transmembrane pressure of about 50 kPa.

Applications of the Ceramic Membranes to Soy Sauce

We developed two types of cross-flow filtration modules with ceramic membranes. Each module was applied to recover soy sauce from sediment. It was confirmed that the permeation flux of the proposed modules were higher than that of the conventional modules, and soy sauce could be recovered from sediment at the yield of more than 90%. It seemed that the proposed modules could work more effectively than the conventional type.