The City of Madisonville's original UV system was placed into service in 1996 when the WWTP was originally constructed. The UV system was designed to treat a peak instantaneous flow of 15.0 MGD. However, heavy rain events produce flows near 20 MGD which is greater than what the UV system was designed to disinfect. At these times, the WWTP could not meet the Division of Water's Fecal Coliform regulation and had been issued a Notice of Violation at least four times since February 2009.
With the inability to consistently meet the Fecal Coliform regulation, it was worthwhile to explore the pros and cons of replacing the UV Disinfection System with a new system. Benefits of the new Trojan UV 3000Plus include:
- Ability to meet current disinfection regulations with a new 24.0 MGD UV system.
- Less lamps (640 now versus approximately 200) to treat a greater flow (24.0 MGD versus 15.0 MGD).
- Lower energy costs even at full intensity.
- The ability to vary intensity based on flow/demand yielding more energy savings.
- Automatic self-cleaning lamps. Operators will not have to shut down a bank or channel to remove lamps manually.
- A complete monitoring system allowing operators to view system history, etc.
Most of the advantages listed above have monetary values that were used to calculate a life-cycle-cost comparison between continuing to operate the current system and replacing the system. The City will save about $12,000 per year on power alone and will be able to meet its disinfection regulation for years to come with the new UV system.