The keys to unlocking many of the causes of membrane fouling can come directly from close
evaluation of the membrane surface itself. Deposits, which accumulate on the surface of the
membrane, can be used in their own identification. The location and concentration of these
deposits can lead to an understanding of the hydrodynamics through the spiral-wound element
and the feed water spacer.
As part of a quantitative research study, twelve DL4040C (4. diameter x 40. length) spiral
wound membrane elements manufactured by Osmonics DESAL were dissected and examined to
determine what surface patterns may be characteristic of natural organic matter (NOM) and
particle fouling. Experiments were conducted with waters that had
been spiked with concentrated NOM and particles. Four NOM concentrations (i.e., 0, 5, 15, and
25 mg/L as total organic carbon or TOC) and three particle size ranges (i.e., no added ancillary
particles, 0.5-1.0 um particles, and >1.0 um particles) were tested resulting in a total of 12
experiments. Each experiment was conducted with a new spiral wound element, which was
dissected immediately following testing.
Two types of membrane surface evaluations were performed: visual and microscopic. Visual
evaluations were performed by scanning cut sections of membrane leafs (8.5 x 11 inches)
directly into the computer using a flatbed scanner. Images were enhanced and magnified using
Adobe PhotoShop. Microscopic evaluations were performed on specimens cut from membrane
leafs and viewed under a scanning electron microscope (SEM). In conjunction with the SEM,
energy dispersive spectrometry was used to generate spectra to confirm NOM deposits as well as
identify mineral deposits. For clarity, SEM micrographs were inserted into each respective
spectrum as a point of reference. Includes 2 references, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 4.5 MB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 11 |
| Published : | 06/16/2002 |
