Where it all goes

Have you ever wondered what happens when you flush your toilet in Cranbrook?

The City of Cranbrook has upgraded the mechanical aerators at its lagoons to a continuous-bubble diffuser system. The new system uses less energy and it gives microbes the air they need to break down biological material. There are no chemicals used in this process, said Joe McGowan, the City’s director of public works. — Photo courtesy City of Cranbrook

It may sound like a complicated process, but the City of Cranbrook’s wastewater treatment and redistribution system is actually quite simple.

When we flush our toilets, wash dishes or have a shower in town, the wastewater enters the main sewage system and flows by gravity to the lagoons at the east end of the city, where the solids are removed and the biological material left behind gets eaten by "bugs"—or microbes. A continuous-bubble diffuser system provides the microbes with lots of air, giving them a boost of energy, and this makes them grow and eat faster. Joe McGowan, the director of public works for the City of Cranbrook, likened this stage of the process to giving Ben Johnson steroids.

After going through three stages of aeration, the treated wastewater is pumped into ponds at the spray-irrigation site, where the microbes—as well as any bacteria and viruses that may be present—are wiped out by ultraviolet (UV) technology. Once the entire process is complete, the treated wastewater is then distributed onto the fields through low-pressure spray nozzles on pivots.

McGowan said the process is designed to mimic what happens naturally.

“Our treatment is basically nothing but air and UV,” he said, later adding, “What we do is a partnership with nature.” 

For other stories related to the City of Cranbrook's wastewater improvement project, see Cranbrook Wins on Wastewater Management and Hats Off to the Ranchers.