Mass and flow balances for reverse osmosis virus removal crediting with tracers.

Constituents in the feed of reverse osmosis (RO) processes pass into the product by two mechanisms: diffusion through the membrane and advection through defects in the system. While minerals and tracers pass via both mechanisms, pathogens pass only via advection. Using mass and flow balances, a rigorous model is developed to characterize the response of both viruses and tracers in RO systems. The model is used to assess several tracers being considered today. Early virus testing and the commercial requirements of desalination are reviewed, leading to the conclusion that some degree of advection can be expected to be present in RO systems but that commercial incentives can be expected to maintain pathogen removal due to defects somewhat greater than 4.0 log. Model results suggest that the best tracers currently in use can detect defects near this log reduction value but that there is still room for improvement. [ABSTRACT FROM AUTHOR]