Extra-cellular polysaccharides (EPS), soluble microbiological products (SMP), dispersed bacterial cells, and a well-characterized natural organic matter (NOM) isolate were observed to determine their influence on the flux decline of model nanofiltration membrane systems. Biofouling tests were conducted using bench-scale, flat-sheet membrane modules, fed with particle-free (laboratory) waters and natural waters, some of which were augmented with readily biodegradable organic carbon. The modules were operated 6.7 x 10(5) Pa, and 21+/- 2 degrees C. Membrane flux-decline was associated with increases in surface EPS mass: between 30 and 80% of normalized flux decline occurred when membrane-associated EPS content increased from 5to 50 microg/ cm2. As judged by standard culturing, heterotrophic cell densities recovered from membrane biofilm samples showed no significant correlations with the different carbon sources present in the feedwaters, or flux decline rates. Results suggested that, in the absence of microbiological activity, SMP and NOM have intrinsic membrane fouling properties at levels that are operationally significant to commercial-scale membrane treatment practices. Results also suggested that SMP may have a biofouling potential significantly greater than some types of NOM. Trends obtained relating these compounds with flux decline were successfully described by expanding existing resistance-in-series models.

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A study was performed for the GVRD to select the ozone dose that results in a higher UVT (UV Transmittance) and reduced DBP formation potential, at the most economical life cycle costs of ozone and UV treatment. The GVRD treats its Coquitlam source with ozone, to meet Giardia and virus inactivation requirements. Currently, the Coquitlam Facility does not meet Cryptosporidium inactivation requirements (3-log). Because the ozone dosage required for Cryptosporidium inactivation is cost prohibitive, UV treatment was selected to provide for adequate log inactivation. Based on pilot and full-scale test results, a model was developed to predict the ozone treated water UVT, which was applied to historical water quality data to evaluate life cycle costs of ozone and UV treatment. In addition, the dosage necessary for control of DBPs, the change in ozone decay rate with increases in pH, and the impact of three quenching chemicals on treated water UVT were evaluated.