무동력 역세척이 가능한 중력식 저압 막여과 공정

Abstract

Gravity-driven membrane filtration refers to a low-pressure membrane filtration method that operates using natural head as operating energy. Unlike the membrane filtration that uses a pump as the driving force, the existing gravity-driven membrane filtration is characterized in that only filtration is performed without backwashing. Therefore, as the operation progresses, the production water quantity decreases compared to the initial filtered water quantity due to contamination, and the operation is performed while maintaining the filtration flux in a low range. The present, we developed a gravity-driven membrane filtration process that enables backwashing of power-type membrane filtration using natural head like gravity-driven membrane filtration. In order to confirm that backwashing is possible only with natural head, an experiment was conducted to confirm that the filtration and backwash fluxes are the same regardless of the incoming direction of the hollow fiber membrane under the same head level conditions. The experiment was conducted by configuring the device up to 2 m, which is the maximum head level that can be secured on the lab scale experimental device, and it was confirmed that the filtration and backwash fluxes were the same at the same head level. A long-term non-powered backwash experiment was conducted under various conditions depending on the backwash head level, water quality, and arrangement of membrane modules. As a result of the experiment, assuming that the same amount of backwash water is used for backwashing, it was efficient to proceed with a high backwash flux in a short time and to arrange the membrane vertically. In the conventional gravity-driven membrane filtration method, the starting filtration flux of 25 LMH was reduced to about 6.1 LMH after 100 hours of operation, while the process of this study maintained 21.2 LMH compared to the same filtration flux and operating time. If this process is applied, the flux reduction can be delayed. Even if it is driven with the same mechanism as the powered membrane filtration, it is possible with little energy.