High-pressure (HP) membranes, reverse osmosis, and nanofiltration are used increasingly to treat brackish and organic laden surface waters as water purveyors are forced to utilize lower quality source waters to meet potable water demands. In addition, reverse osmosis has become an integral part of the advanced reclamation process for the indirect potable reuse of domestic wastewaters. In these applications, HP membranes are expected to serve as a positive barrier to pathogens. To date, integrity methods for full-scale HP membrane systems have been limited to conductivity and total organic carbon monitoring, approaches that can only assess pathogen removals to two logs (99%). The first objective of this research was to determine the integrity of RO and NF membrane systems with respect to viral passage using both particulate (MS2 viruses and fluorescent microspheres) and soluble (Rhodamine WT) surrogates. The second objective was to compare the capability of these surrogates for use in assessing integrity of intact and compromised RO and NF membranes when evaluated in a number of configurations. Originally published by AwwaRF for its subscribers in 2003
The results from this research affirmed the fact that inactivation of microorganisms by chemical disinfectants is influenced by disinfection, microbial, and water quality factors and the various interactions between these factors. The results showed that for all disinfectants, temperature is a key parameter that influences disinfection efficiency. The effect of turbidity was generally of less importance than pH and temperature. The safety factors (1.5 to 2.0) that are applied in the USEPA Ct tables should be satisfactory to account for these effects, not to mention the additional safety factors that are employed during Ct calculations (Cresidual and t10). Research Partner: USEPA Originally published by AwwaRF for its subscribers in 2003
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