From the Littleton Independent (Tom Munds):
Littleton’s city council hired consultant CH2M HILL to do an independent evaluation of the immediate need for a UV system. The CH2M HILL report to the joint city council meeting stated the plant will eventually have to install a UV system but it doesn’t have to be done right now because the current process meets all federal and state treatment standards. The plant on South Platte River Drive provides wastewater treatment for 300,000 regional customers. It is jointly owned by the two cities so the ultimate decision to proceed with any capital project rests with the two city councils…
Paul Swaim, CH2M HILL vice president of global technology for water treatment, said future regulations probably will mandate installation of a UV process. However, he said based on evaluation of plant data from January 2009 until March 2011, the current system provides wastewater treatment that meets the 2014 standards for ammonia removal and treatment for E.coli. However, even though the current process is very complex, there appears to be a low risk of compliance failure. CH2M Hill representative Larry Schimmoller, global technology leader, water reuse, said ammonia removal is particularly complex because, at a later treatment stage, a small amount of ammonia must be mixed with chlorine to provide disinfection. Then another chemical must be added to remove the chlorine before the treated water is returned to the river. He said while the current system meets ammonia removal limits and requirement for treatment for E.coli, installation of UV disinfection would create provide a less complex treatment system and eliminates the need for chlorine use. Both men said the UV system is effective and they reported 13 of the 15 wastewater treatment plants in Colorado surveyed used UV disinfection.
More wastewater coverage here.