NAMS 2002 Workshop - ICOM 2008

greatly elevated total suspended solids (TSS), turbidity and dissolved organic
carbon (DOC). The MF and UF filterability trends were statistically analyzed
including and excluding the data for this sample.
The turbidity, total algal count and TSS levels showed greater variation over
October 06-March 07 (ie., the warmer months) than for the April 07-December 07
period. Some correlation between these parameters and DOC was apparent.
There was a trend for lower turbidity over the April 07-August 07 period, and
similarly, although to a lesser extent, for total algal count.
TDS and conductivity levels were fairly consistent over the February-December
07 period, although slightly lower levels in July-August may be indicative of a
minor seasonal trend.
The MF filterability of HORS samples was generally higher for the March-
December 07 period and this was reasonably consistent with their relatively low
turbidity, TSS, algal contents and low DOC. TSS level was the major determinant
of MF flux, MF filterability decreased to varying extents with increasing levels of
these parameters in the order TSS > turbidity > total algal count > DOC whether
an algal bloom was present or not.
The UF filterability of HORS samples was also generally higher for the March-
December 07 period. UF filterability decreased to varying extents with increasing
levels of TSS, turbidity, algal count and DOC such that the effect of DOC > TSS
> turbidity > total algal count. When data pertaining to the presence of an algal
bloom was included this order changed so that the effect of TSS level was
greater than DOC concentration on UF flux.
Seasonal water quality changes had a greater impact on MF rather than UF
filterability, which implies that UF is a better choice than MF for pre-treatment for
RO in terms of consistent performance. Pre-treatment of the feed would improve
water quality and thus filterability, particularly during algal bloom events, enabling
more consistent membrane performance.