AWWA MTC69667

The feasibility of an ED (electrodialysis) application to a drinking water softening process has been assessedusing a mathematical model. A one-dimensional analytical model was built to describe the steady stateionic transport in an ED system by solving the Nernst-Planck equations with the electroneutralityassumption. The model simulates three ions (one anion and two cations with different charges) through adiluate boundary layer, cation exchange membrane, and concentration boundary layer. The model studyfound that the relatively low ionic concentration required for the effluent of the softening process causesthe ED system to operate near the limiting current density. Near the limiting current density, the ionictransport is rate-limited at the diluate boundary layer, and it has been shown that the relative calcium fluxcan be accelerated by shrinking the diluate boundary layer. The preference of the cation exchangemembrane to divalent ions is proven not to affect the relative calcium flux when the ED softening isoperated near the limiting current density. Includes 7 references, tables, figures.

Product Details

Edition:

Vol. - No.

Published:

11/01/2009

Number of Pages:

9

File Size:

1 file , 1000 KB