Constant rate permeat experiments using polyethylene hollow fiber membranes were conducted in order to treat dam water for potable purposes. The experiments consisted of two series. One series consisted of six bench scale apparatuses, each having a $0.4m^2$ nominal permeat area, which were applied in determining the optimum operating conditions. The other series was comprised of two pilot scale plant, each having a $40m^2$ nominal permeat area. Both series were operated for six months. Coagulant was not used in any of the experiments. To suppress an increase in differential pressure between the inlet and outlet of the membrane, a hydrophilic membrane was found to be better than a hydrophobic membrane. Also, permeat flux should not be more than 0.03m/h, and air bubbling-washing for 1 minute should be conducted at 180 minutes intervals or less.

• 조봉연(동경대학 공학부 도시공학과) | Cho Bong Yeon