From the Englewood Herald (Tom Munds):
Dennis Stowe, plant manager, said the current chlorine system does a pretty good job of killing bacteria but new technological data reports the ultraviolet system provides better disinfection action on some bacteria than chlorine. Also, the chlorine used is similar to bleach. But while the chlorine is a good disinfectant, federal and state requirements mandate that an additional chemical must be added during the process to remove the bleach-like material before the water is allowed to flow into the river because it is bad for the aquatic life, Stowe said. “The system we are testing disinfects with the portion of the ultraviolet rays that cause sunburn,” he said. “Those rays eliminate the bacteria by making them infertile so they die out. It also means there are no chemicals to remove before the water is put into the river.”
The plant has already tested one company’s system and currently is putting another company’s system through its paces. For about the next two months, plant crews will have the pilot-project system up and running so the technicians can collect performance data on the disinfection performance of the ultraviolet system. “We’ll evaluate the data to determine if we definitely are going to move forward with an ultraviolet disinfection system,” Stowe said. “Once all the data is collected, it’ll take a couple months to complete the evaluation. Then, if we decide ultraviolet is a better disinfecting system, we’ll begin the process necessary to move ahead with eventual installation.”[…]
Provided the state approves the plan, the plant will design the project and begin installation. Stowe said the target date for switch over to ultraviolet is 2014 and the project will cost $8 million to $10 million. He said the cost of operation for the chlorine and ultraviolet system will be about the same because while chemical costs will be less, the ultraviolet system uses more electricity.
More wastewater treatment coverage here.