Microbial Removal and Integrity Monitoring of High-Pressure Membranes Used For Water TreatmentEPA Grant Number: U915208
Title: Microbial Removal and Integrity Monitoring of High-Pressure Membranes Used For Water Treatment
Investigators: Colvin, Christian K.
Institution: University of Illinois at Urbana-Champaign
EPA Project Officer: Lee, Sonja
Project Period: January 1, 1997 through January 1, 1999
Project Amount: $68,000
RFA: STAR Graduate Fellowships (1997) RFA Text | Recipients Lists
Research Category: Academic Fellowships , Engineering and Environmental Chemistry , Fellowship - Civil/Environmental Engineering
The objective of this research project is to investigate the mechanism that allows for microbial contaminants to pass through reverse osmosis and nanofiltration membranes, contaminating the effluent drinking water. A surrogate indicator is being developed to assess possible transport mechanisms. Criteria for surrogate indicator selection include analytical simplicity and transport similarity with microbial contaminants. Experimental sets are designed to assess the permeation of both microbial contaminants and surrogate indicators with particular emphasis on the role of concentration polarization and membrane imperfections.
To develop a surrogate indicator to model the passage of microbial contaminants, tests will be conducted on a closed-loop system containing four flat-leaf membrane cells connected in series. The surrogate indicators that will be considered include fluorescent-dyed polystyrene microspheres and Rhodamine WT. Microsphere sizes will be chosen to correspond to the sizes of the microbial contaminants to be modeled, such as Cryptosporidium parvum and MS2 phage virus. The size of microspheres that best models the microbial contaminants being studied will be compared to the other surrogate indicator, Rhodamine WT. Only one of the surrogate indicators, microspheres or Rhodamine, will be chosen, depending on which best models the actual rejection characteristics of the microbial contaminants. The chosen surrogate indicator will subsequently be used to investigate the role of concentration polarization on the passage of microbial contaminants. Different sizes of microbial contaminants will result in different concentration polarization levels and, therefore, affect the overall rejection. In addition, three different temperatures ranging from 5 to 25°C as well as four different fluxes ranging from 8 to 20 gfd will be tested. The last set of tests will investigate the effect of imperfections on membrane performance. Manufacturer’s recommendations will be considered when choosing the imperfections tested. Possible imperfections include air ripping, chlorine oxidation, and any other imperfections that do not result in gross leakage of solute.