Evaluating Microbial Removal by Low-Pressure Membranes at a Water Reclamation Facility

The primary goal of this WRF funded research was to quantify the microbial removal by MF and UF membranes with various feed water qualities and operating conditions. Seeding challenges were conducted with the continuous microfiltration (CMF) and submerged-continuous microfiltration (CMF-S) pilot units at the Scottsdale Water Campus, AZ (SWC, water reclamation facility using secondary clarified effluent). Results obtained with the pilot units under clean water conditions have shown that Pseudomonas diminuta was completely removed (∼ 5.0 log-units). PRD1 phage removal varied between 0.3-1.8 log and removal of MS2 phage varied between 0-1.1 log. Short- and long-term fouling experiments with secondary effluent showed that deposition (cake) and hydropneumatically-irreversible fouling can induce additional phage removal to a variable extent depending upon the size of the microorganism, the feed water quality and the decline in specific flux. Microbial rejection results using waters of varying quality and membrane types are compared and presented.