How McGill University is winning using sustainable technology to reduce its Legionella risk

The Challenge

The McIntyre pavilion houses the prestigious medical faculty in a 15 story building with 1,600 square feet per floor. To ensure HVAC cooling needs, the pavilion relies on two 850 ton cooling towers with 15,000 liters (4,000 gallons) of water. Despite maintaining a chemical treatment program, the towers were often affected by a high bacterial count (>10⁵ UFC/mL) and several cases of Legionella bacteria. The HVAC department was seeking a better and proven alternative to reduce its chemical footprint while minimizing the bacteria counts and eliminate the Legionella outbreaks. The province of Quebec requires that cooling tower owners test Legionella monthly using an accredited laboratory.

The Solution

After having been contacted in 2018, EM03 addressed the problem by installing the Insitu-03^TM water treatment solution. Integrating EM03’s high capacity Taurus^TM ozone cell. Among McGill’s needs was a hands-free system. Thus, the system came equipped with PLC plus sensors and a water pump to ensure continuous water treatment. One property of ozone that is without equal is its oxidizing capability to disinfect water. Using ambient air, ozone is produced on site, a sterling example of green technology using ambient air.

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The Insitu-O3^TM incorporates a closed loop, continuous cycle water treatment thus avoiding sequential biocidal injection cocktails. The Insitu-O3^TM is independent of the thermal load of the chillers, thus providing a continuous water treatment. In addition, several sensors provide optimal control, alarm reporting and logging capability for the operators

Since 2019, McGill has achieved bacteria counts less than 10³UFC/mL and has had no Legionella counts in the tower. Furthermore, McGill has eliminated the recurring need for biocide as well as the handling and managing of dangerous chemical products.

The Results

Solutions often can be considered “pain relievers”or “gain creators”. In the case of McGill University,the solution was both and manifested in two ways: (1) mitigating Legionella risk through a sustainable water treatment. While at the same time, (2) allowing the university to see significant savings in recurring chemical costs. According to Sean Dolphin, HVAC Supervisor, “We have been impressed by the performance of the Taurus^TM series ozone cells on the cooling tower and its water treatment. Its ease of use and hands-off approach has provided peace of mind for members of the mechanical staff.” Since installing it in 2019, results have been exemplary with some of those benefits listed below:

Complete elimination of biocides representing a savings of $12,000 per year.
Elimination of storing and handling of dangerous products resulting in an improvement in occupational safety.
Elimination of disinfection procedures for Legionella detection representing an annual maintenance cost reduction of $2,000.
Water savings in reduced blowdown by improving cycles of concentration resulting in a reduction of water consumption of 54,000 liters per year.
Legionella: The client is required to sample on a monthly basis all serogroups of Legionella. Since the installation in 2019, there has been zero Legionella detection.

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