Use of ATP to identify poor- performing filters Al Parrella Western Lake Superior Sanitary District Duluth, MN

Add bleach here Final effluent

Problem statement: Bacteria increases across effluent filters – Seems to be a seasonal phenomenon (worse towards end of season)

Fecal coliform, before and after filters Monthly geometric mean

Problem Limit

Troubleshooting Use of ATP pen Test ATP at various location including the effluent of each filter Results reported as difference between total and free

Results Clearly there was a problem with number 11 filter Found several mechanical issues related to backwash system

Conclusion Its hard to clean 100+ tons of media

Steps Start meter Obtain sample Submerge pen Break ampule Mix Obtain reading – Units are in relative light units

Thanks to… …Roger Sandstrom, Treatment Plant Operator Kathy Hamel, PE, Operations and Maintenance Supervisor, Clean Water Production