In what is said to be the largest municipal wastewater application using peracetic acid (PAA) disinfectant to date, the Metro Wastewater Reclamation District in Denver, Colo. recently began disinfecting wastewater effluent with a PAA formulation from Enviro Tech Chemical Services, Inc. (Modesto, Calif.; www.envirotech.com) known as Peragreen WW.
PAA is a disinfectant alternative to sodium hypochlorite that allows users to avoid permitting and regulatory issues associated with toxic halogenated byproducts from chlorine-containing disinfectants. While it is more expensive than sodium hypochlorite, PAA is a more potent oxidizer, so it can reduce overall chemical use. Peragreen WW is an equilibrium 15% PAA solution that is stabilized in a proprietary formulation.
The application of PAA is accomplished by metering skids engineered by Stantec Engineering (Edmonton, Alta.; www.stantec.com). The skids contain peristaltic pumps with specially designed tubing made from Teflon and silicone. Enviro Tech installed plastic storage tanks for the PAA system that feature a proprietary medium-density polyethylene liner with high chemical resistance.
The new bulk delivery and dosing system at the Denver wastewater plant has a capacity of more than 30,000 gal of PAA solution. The wastewater treatment system is capable of handling 220 million gal/d with a daily average flow of 146 million gal/d, Enviro Tech says. The company has been supplying the food industry with PAA and other disinfection products since 1991.