AWWA WQTC62469

The objectives of this study were to determine the effects of solution chemistry on chemicalcleaning of nanofiltration (NF) membranes fouled by natural organic matter (NOM) and to evaluate theefficiencies of common chemical cleaning agents.Membrane filtration experiments were conducted under various solution conditions usingSuwannee River humic acid (SRHA) and Suwannee River natural organic matter (SRNOM) as the modelNOM foulants. To study NOM fouling and chemical cleaning in the presence ofcolloidal foulants, silica colloids of different particle sizes were used in someexperiments. Two types of NF membranes with different surface properties, NF 270 andNF 90, were tested. Ionic strengths ranged from 10 to 100 mM and Ca²⁺ and Mg²⁺ wereused to study the effect of divalent cations. Four model chemical cleaning agents:deionized water, basic solution (NaOH), a metal chelating agent(ethylenediaminetetraacetic acid, EDTA), and an anionic surfactant (sodium dodecylsulfate) were evaluated.Fouling/chemical cleaning experiments were conducted in a bench-scale continuous-flowdead-end filtration system. The effectiveness of chemical cleaning was assessed based onthe permeate flux recovery following the chemical cleaning. For feed stream containingonly NOM foulants, the presence of Ca²⁺ tremendously enhanced the fouling process, butthe membrane flux behavior in the presence of Mg²⁺ was similar to that when onlymonovalent cations, i.e., Na²⁺ was present. Includes figures.

Product Details

Edition:

Vol. - No.

Published:

11/01/2005

Number of Pages:

3

File Size:

1 file , 150 KB