AWWA MTC64501

Membrane fouling of ultrafiltration membranes by natural organic matter (NOM) hasbecome an important concern in advanced water treatment applications. Surface water,after pre-filtration with a 0.45µm filter, was separated into colloidal and non-colloidalNOM through dialysis with two types of dialysate (deionized water and a syntheticsurface water solution). Filtration experiments were conducted at constant flux (138.5L/m².hr) running 10 filtration cycles of 30 min, followed by immediate backwashingwith permeate water. Results of dialysis showed that circa 33-40% of the total dissolved organic carbon (DOC)(~17mg/L) of pre-filtered surface water was colloidal NOM, in the size range 1.3nm-0.45µm; and ca. 60-67% was non-colloidal NOM (<1.3nm). Colloidal NOM wascomposed mainly of polysaccharides and humics. However, the inorganic colloidalconcentration was assumed to be below 0.5mg/L (total silica content measured by ICP).The non-colloidal NOM comprised humics, building blocks, neutral amphiphilics andlow molecular weight acids. Results of ultrafiltration (UF) filtration tests of pre-filtered 0.45µm andcolloidal NOM revealed that colloidal NOM was responsible for the major increase intransmembrane pressure (TMP) during ultrafiltration. LC-OCD analyses identifiedpolysaccharides as foulants that were backwashable. UF filtration test of non-colloidalNOM with a DOC concentration of 5mg/L, also resulted in an increase in TMP overtime. Simulations of surface water fouling were made using the normalized noncolloidalNOM (~11mg/L) and colloidal NOM (~6mg/L) fouling results, and thesimulated increase in TMP matched the surface water quite well. Includes 22 references, tables, figures.

Product Details

Edition:

Vol. - No.

Published:

03/01/2007

Number of Pages:

10

File Size:

1 file , 380 KB