AWWA MTC69700

This powerpoint presentation begins by presenting the problem statement concerning nanofiltration:nanofiltration (NF) has an attractive capability of rejectingmultivalent ions at a much lower pressure than that used forreverse osmosis (RO);NF productivity is generally hampered by multicomponent foulingcaused by colloidal materials, dissolved organics, inorganicprecipitates, and microorganisms accumulating on the membranesurface; and,foulant-foulant interactions cause much more complex foulingbehaviors than those of individual fouling phenomena.The research goal was to develop an integrated model that has the ability to:describe combined fouling due to three different foulants;unify two-component fouling models such as cake-enhanced osmoticpressure and bi-dispersed colloidal fouling; and, include all the single-component fouling scenarios. The theory is presented and is broken down into singlet fouling, doublet fouling, triplet fouling, and equivalent flux. Presentation conclusions indicate the following: a novel theory was developed on the basis of the Happel's cell model toanalyze the combined fouling of colloids, macromolecules, and soluteions;resistance of the combined fouling is much greater than eachfouling of colloids-alone and macromolecules-alone cases; at the beginning of dead-end filtration, BSA gel layer undergoesremarkable structural compression with increasing volume fraction,while alginate and dextran do not;colloids and BSAs are not well mixed during the early stage of thefiltration, causing theoretical under-prediction of the permeate flux; and,theoretical flux of combined fouling and the equivalent flux of theweak form provide the lower and upper bounds of the experimentalflux of the triplet fouling; therefore, using measurement of individualfouling phenomena of colloids-alone and macromolecules-alone cases,the permeate flux of triplet fouling can be well estimated. Includes figures.

Product Details

Edition:

Vol. - No.

Published:

11/01/2009

Number of Pages:

24

File Size:

1 file , 13 MB