AWWA ACE59833

The effects of fiber length and aeration rate on permeate flux decline in tests of a single,submerged hollow fiber at constant pressure are presented. Without aeration, the initial rateof flux decline was greater for a longer fiber length (1 vs. 0.7 vs. 0.3 m) at a relatively lowfeed concentration of bentonite particles (100 mg/L). However, the same pseudo-steadystate in permeate flux was observed for all three fiber lengths as fouling progressed. Thefouling rate was greatly reduced by aeration for all three fiber lengths. However, the effectwas larger as fiber length became shorter. It was concluded that aeration was not aseffective for removal of the fouling layer formed near the fiber outlet where the local flux ishighest for the longest fiber length. Permeate flux decline (without aeration) was overpredicted by using the specific cake resistance from a small-scale, flat sheet test in ahollow-fiber model. The explanation may involve the effect of axial gradient of pressuredrop on local specific cake resistance for compressible cakes. Small-scale tests cannotaccount for this axial dependency. Includes 8 references, figures.

Product Details

Edition:

Vol. - No.

Published:

06/17/2004

Number of Pages:

14

File Size:

1 file , 580 KB