Water Resources Research Act Program

Details for Project ID 2011NC160B

Identification of membrane foulants and optimum cleaning strategies for nanofiltration and reverse osmosis membranes treating groundwaters from the Castle Hayne and Peedee aquifers

Institute: North Carolina
Year Established: 2011 Start Date: 2011-06-15 End Date: 2012-06-14
Total Federal Funds: $25,666 Total Non-Federal Funds: $44,681

Principal Investigators: Orlando Coronell

Project Summary: The North Carolina Cape Fear Pubic Utility Authority (CFPUA) uses ground water from the Castle Hayne and Peedee aquifers as feed for their 6-MGD nanofiltration (NF)treatment plant. CFPUA reported difficulties identifying the foulants responsible for decreased membrane performance and identifying optimum membrane cleaning strategies that would prevent pre-mature membrane damage. Such problems have regional relevance because: (i) half of North Carolina population relies on groundwater; and (ii) NF and reverse osmosis (RO) have become increasingly attractive groundwater treatment technologies due to salt intrusion into fresh aquifers and regulations requiring the removal of a broad range of water contaminants. Accordingly, in this study we will identify both (i) the main foulants and (ii) the optimum cleaning strategies for NF and RO membranes filtering groundwaters from the Castle Hayne and Peedee aquifers in North Carolina. Outcomes will also include recommendations of pretreatment strategies that would mitigate fouling in NF and RO membranes filtering the studied waters. Characterization methods using Rutherford backscattering spectrometry (RBS), recently introduced to the membrane field by the PI and collaborators, will be used for the first time to characterize foulant layers and fouled membranes. The characterization work will generate original knowledge concerning (i) foulant deposition within the ultrathin (~100 nm) rejecting barriers of NF/RO membranes, and (ii) foulant distribution throughout fouling layers. Experimental methods will include analysis of inorganic and organic matter in the waters tested, membrane fouling tests to assess flux decline due to fouling, membrane autopsy tests to identify membrane foulants, and testing of membrane cleaning strategies.