On-Site Evaluation of Electropositive Filtration for Fouling Control: Case Study in a Water Reuse Desalination System

Cartridge filters are used as a prefilter to reverse osmosis (RO) membranes to reduce membrane fouling during operation. However, cartridge filters typically serve as a physical barrier for foulant removal. This study reports a side-by-side comparison of an electropositive filtration (EPF) cartridge (NanoCeram) with a conventional string-wound filtration (SWF) under full-scale operating conditions at the Scottsdale Water Reclamation Facility (Scottsdale Water Campus). A customized two-stage RO test bed operating at 500 gal per day and 25%-40% recovery was used to evaluate the performance of EPF over an 8-week period. Performance metrics included RO permeate flux stability, membrane fouling analysis, and specific energy consumption of water production. The EPF filter was found to reduce membrane fouling, resulting in a ~20% increase in RO permeate flux and 13%-18% decrease in energy consumption in the unit operating with the EPF compared to the one using the conventional SWF. In addition, the presence of a carbon filter prior to the EPF filter was found not to be needed for its good operation. This study is the first report of an on-site trial of EPF cartridge filters for RO fouling mitigation in a wastewater reuse setting.