AWWA WQTC69419

The State of California Department of Public Health (CDPH), Title 22 Code of Regulations, Subsection 60301.230 requires that a utility demonstrate at least a 5 log (99.999%) reduction in bacteriophage from tertiary treated wastewater after treatment with methods other than chlorine disinfection. In order to meet these requirements, The City of Fresno, CA (the City) Wastewater Management Division employs a post-secondary pond and substrata infiltration system as part of their treatment. The City has used the concentration of male-specific (MS) phage in their pre-pond secondary effluent compared to the MS phage concentration in monitoring wells. U.S. Environmental Protection Agency (USEPA) Method 1601 has been validated for use to demonstrate presence/absence of phage in 1L samples of groundwater. Using USEPA Method 1601, the pre-pond secondary effluent typically does not have MS phage concentrations large enough to demonstrate the required 5-log reduction at the monitoring well by this method. The purpose of this study was to adapt and validate the presence/absence format of Method 1601 to a most probable number (MPN) format in large volumes (> 10 L) so that a 5-log reduction of phage could be documented. There were two MPN formats studied. One consisted of three 10L, three 1L and three 100 mL volumes; the other was three, 100 L filter concentrated volumes. The validation procedure used was that described in USEPA Method 1601 for Tier 1 of USEPA's performance-based measurement system (PBMS) (modification at a single laboratory). Based upon the PBMS, CDPH requested that this study include 10 replicates of spiked reagent water, 10 replicates of spiked matrix water and associated method blanks. In addition, based upon the original national validation study of Method 1601, CA DHS requested a phage concentration at 1-2 pfu/spike of target volume test water. The 33.3 L MPN format was validated in both reagent grades water and groundwater matrix. Includes 3 references, table.