2006 Volume 7 Issue 3 Pages 189-195
In our previous paper, ultrafiltration (UF) membrane modules were evaluated for clarification of rice washing and soaking drainage from packed rice cake manufacturing plant. And a hollow fiber membrane module of the molecular weight cut off of 150kDa, made by polyethersulfone, was found to be the most suitable. In this paper, suitable operating condition of above membrane module was studied. Drainage were obtained from a rice washing process, composed of five steps of washing and one step of soaking. The drainage from each step was filtrated by the OF membrane, and 80% of each drainage was recovered as permeate for recycling. From the view point of permeation flux and flux restoration rate by membrane washing, the various operating condition was evaluated. As the first and the second step drainage showed extremely low flux and low restoration rate, we concluded that the both drainage are not suitable for recycling after OF treatment and should be treated by active sludge processing as waste water. The third to the fifth step drainage showed higher flux and higher restoration rate than the first and the second steps, and the higher step drainage showed the higher flux and the higher restoration rate. Soaking drainage showed extremely higher flux and higher restoration rate than those of washing drainage. It was concluded the suitable OF operating condition for rice washing drainage treatment for clarification was 0.02 MPa pressure and 0.9m⋅s-1 flow velocity, and that for soaking drainage was 0.1 MPa pressure and 0.9m⋅s-1 flow velocity.
