Nanomembranes - Nanotechnologies for Water Environment Applications - page 384

The raw water DOC ranged between 4 and 7 mg/L while the permeate DOC was
constant at 0.15 mg/L. Of the permeate DOC, 60% was composed of amino acids, 18%
of sugars, 15% of fatty-aromatic acids, and 7% of aldehydes. The BDOC (concentration
not stated) composition was 63% amino acids, 22% sugars, 10% fatty-aromatic acids,
and 5% aldehydes. In the study, it was concluded that amino acids passed through the
NF membranes, and they are usually readily available to bacteria (AOC-forming
compounds). Thus, different researchers observed that, even though membrane filtration
considerably reduces the DOC in the feed solution, it might let through a significant
portion of the raw water AOC and BDOC. The Méry-sur-Oise plant has been using NF
membranes (NF200) to produce safe drinking water since 1999 with various pre-
treatments including conventional surface water treatment followed by ozonation, acid
addition to pH 6.9, antiscalant addition, and MF (6 m). Being the largest NF plant with
a maximum productivity of 340,000 m 3 /d, total 90,000 modules were employed
(Ventresque et al., 2000). A more recent study on water quality was conducted by Peltier
et al. (2003) just north of Paris in the service area of the Méry-sur-Oise water treatment
plant. The final water is a mixture of 20% from the conventional train and 80% from the
NF train (Figure 12.9). In total, 20 sampling campaigns were performed at 15 locations,
focusing on turbidity, trihalomethanes (THM), free chlorine, total organic carbon (TOC),
dissolved organic carbon (DOC) and biodegradable dissolved organic carbon (BDOC).
The BDOC content of the water entering the drinking water network was equal to or
lower than the detection limit for the method used (0.1 mg C/L).

)HHG +/ 1) ;/(

V\QWKHWLFZDWHU /DNH*UHLIHQVHH
ZDWHU

/DNH*UHLIHQVHH
ZDWHUVSLNHG

/DNH=XULFKZDWHU /DNH=XULFKZDWHU
VSLNHG

Figure 12.8 AOC concentration measured before (feed) and after NF (HL, NF270) or
RO (XLE) membrane filtration from 5 different samples.