After a water main is installed or rehabilitated, it must be disinfected to protect against microbial contamination of the public water supply system and waterborne disease outbreaks. The industry standard of using a chlorine-based disinfectant is time consuming, expensive, and potentially harmful to the environment.
Denver Water, in search of a green alternative to the traditional chlorine method, partnered with CDM on a 3-year study. The ground-breaking research revealed that ozone, when combined with an innovative high-pressure spray wash pre-cleaning system, effectively disinfects water mains with no risk to the environment or to workers. Denver Water has successfully incorporated the new method into their standard distribution system disinfection processes. In addition, interest from several water utilities and federal regulatory agencies predicts a new industry trend and best practice.
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Ozone presents no risk to the environment - it typically converts into oxygen within 1 hour in a closed pipeline. Chlorinated water must be dechlorinated before it can be safely discharged into the environment.
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A trailer-mounted ozone generation system pumps ozone directly into the targeted pipe, a simple and relatively safe procedure. In contrast, the chemicals that make up chlorine solutions must be transported, stored, and prepared onsite.
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Ozonation and high-pressure pre-cleaning achieves disinfection in 20 to 30 minutes, significantly faster than the two-step process of chlorination and dechlorination. Chlorination requires a 24-hour holding time in the pipes, and dechlorination can require up to another 24 hours.
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Ozone is approximately 100 times more powerful as a disinfectant than chlorine.
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By reducing labor requirements by 50 percent, ozone disinfection saves Denver Water around $1,000 per pipeline disinfection event.