Minneapolis Flexes its Mussels for Source Water Monitoring Solution

Often called “the liver of the river” because they reduce turbidity and filter out harmful algae, mussels naturally open and close during changes in water quality. The filter feeders eat almost anything they contact in open waters but close their shells if they encounter a contaminant that doesn’t suit their palette, making them the perfect partner for a utility hoping to learn more about their plants’ influent river water quality.

A Biomonitoring System for Drinking Water Treatment

At Minneapolis Water Treatment and Distribution Services, 15 mussels live in a tank where water is continuously cycled in from the Mississippi River. Small magnets and sensors attached to the top and bottom of the mussel shells continuously monitor each mussel’s shell gape (degree of openness) in real time. Badger Meter collaborated with consulting firm Neptune and Company to integrate a myriad of statistical calculations to identify mussel behavior that may indicate the presence of aquatic toxins. If enough mussels exhibit this response within a user-defined timeframe, the system triggers an alert to the utility’s water quality monitoring software, flagging a potential contamination event requiring further investigation.

A spectro::lyser measures source water quality at Minneapolis Water Treatment and Distribution Services.

Above, in that same tank, a spectro::lyser V3 spectrometer probe measures river water quality for benzene, toluene and xylene (BTX), temperature, nitrate, total organic carbon (TOC), dissolved organic carbon (DOC) and UV254. These measurements are communicated back to the utility’s central computer system to provide comprehensive river water quality data and to validate mussel response.

Early Warning, Rapid Response and Utility Benefits

Rapid changes in water quality may also disrupt and/or damage plant treatment processes. The biomonitoring system and spectro::lyser data are used to alert operators to conditions that require responsive action, so that they can avoid costly shutdowns and repairs.

The biomonitoring system in Minneapolis includes a spectro::lyser v3, con::cube v3 IoT terminal and ruck::sack, plus 15 mussels.

While the mussels have been in use in Minneapolis since 2007, a submersible autocleaning brush or ruck::sack was recently added to the spectro::lyser. This addition helps reduce maintenance costs and the time required to manage the water quality monitoring equipment.

“For the City of Minneapolis, a robust water quality monitoring solution protects our 500,000 customers; ensuring that they have safe drinking water,” George Kraynick, Manager, Water Quality and Laboratory Services said. “The benefit of the biomonitoring system is that it provides 24/7, real-time monitoring of the river, which allows us to take action immediately if the water quality parameters change significantly, indicating a contamination event.”