The main limitation of membrane application is fouling, which causes a decrease of
membrane performance and an increase of operating and maintenance costs. Biofouling is
often the deposit component most resistant to chemical cleanings. Consequently,
membrane pretreatment has to be optimized to minimize the biofouling potential of the feed
water. This study focused on
the effect of UV irradiation on NF membrane biofouling at pilot scale in Neuillysur-
Marne Water Treatment Plant (WTP), operated by Veolia Water on behalf of the Syndicat des Eaux d'Ile-de-
France. At this WTP, the conventional process was composed of clarification, sand filtration,
ozonation, granular activated carbon (GAC) adsorption and chlorination. Two identical one-stage NF membrane pilots
and a low pressure UV reactor were implemented and operated during two different tests.
During Test 1, Pilot 1 was fed sand-filtered water (SFW) and Pilot 2 sand-filtered and UV irradiated
water (SF+UVW). During Test 2, Pilot 1 was fed GAC-filtered water (GACW) and
Pilot 2 GAC-filtered and UV-irradiated water (GAC+UVW). The UV dose was fixed at 400
J/m<sup>2</sup> by adjusting the feed flux of the UV reactor. Both NF pilots included a pretreatment step
made of pH neutralization, 20 and 6 µm cartridge filtration, and antiscalant injection.
At the end of both tests, NF spiral-wound modules were autopsied and analyzed. The fouling
deposit was characterized by ATR-FTIR spectroscopy and by epifluorescence microscopy with
different stainings (DAPI for total bacteria counts, SYTO9-propidium iodide for live/dead
distinction, FTIC and TRITC-conjugated lectins for exopolysaccharides visualization). The
deposit dry weight, wettability, ATP and proteins contents were also determined.
Both membrane performances monitoring and foulant analysis indicated that UV irradiation was a
favorable NF pretreatment. The longitudinal pressure drop increase was strongly limited by
UV irradiation. The permeate flux decline was also slowed down by UV, at least after a 10
week filtration time. The deposit is quantitatively reduced and the membrane wettability is
less affected when UV pretreatment is used. All the biofilm parameters (activity, cell counts,
matrix exopolymers) were also decreased. Includes 21 references, tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 1.1 MB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 16 |
| Published : | 11/01/2008 |
