Serving over 200,000 ratepayers, the City of Tacoma operates two award-winning wastewater treatment plants. The Central Wastewater Treatment Plant and the North End Wastewater Treatment Plant are considered state-of-the-art but operate differently. Central uses an aerobic process - high purity oxygen and bacteria - to remove organics from wastewater. North End, a physical chemical plant, uses chemicals to remove the organics and a bacteria filter to treat the wastewater before it enters Puget Sound. Together, the plants treat 100 million gallons per day (MGD) with a combined capacity of 150 MGD during weather events. As the plants have grown over the years, the City of Tacoma continues to add Polyblend® units as the preferred polymer feed preparation system and currently has eight in service between the two facilities.

The Central Wastewater Treatment Plant has many innovative features, including a dual digestion process that produces Class A biosolids and a peak flow treatment facility that can ramp-up treatment during heavy storms to reduce the risk of sewage overflows. The biosolids material processed at the plant is recycled and turned into gardening products - mix and potting soil. There are six Polyblend® DP dry polymer preparation systems currently in service at Tacoma’s Central facility. Five are used to add dry polymer for dewatering and dissolved air flotation applications, including two that were installed in 1985. A sixth Polyblend® DP system was purchased in 2008 as part of an upgrade that expanded the plant’s treatment capacity from 100 MGD to 150 MGD during major storm events.