APPLICATION OF GAS-LIQUID 2-PHASE CROSS-FLOW FILTRATION TO PILOT-SCALE METHANE FERMENTATION

As part of a national project, ''Aqua-Renaissance '90,'' by the MITI, a pilot-scale evaluation of membrane-enhanced anaerobic fermentation, has progressed for the wastewater from a pulp and paper mill. A novel membrane filtration system was newly proposed with the aim of saving e nergy. That is, a gas-liquid two-phase cross-flow filtration which was generated with liquid circulation by an air-lift pump effect, was com bined in the anaerobic bioreactor. It was confirmed that the membrane filtration not only offered very stable and large permeate flux, but e nhanced the processing efficiency by retaining the microorganisms in t he bioreactor. Furthermore, the power consumption per unit permeate vo lume in the membrane system of 1.78 kWh/m3 was achieved, which was a v ery high-performance result from the viewpoint of saving energy, as co mpared with 3 - 5 kWh/m3 of conventional liquid single-phase cross-flo w filtration.