Wastewater Treatment
Collection Sewers• Collect wastewater and bring it to the
wastewater treatment plant– Combined sewer overflows: Take untreated
sewage and storm water to rivers, lakes and Puget sound during heavy rain events
Preliminary Treatment
– Bar Screen: located at the beginning of the wastewater treatment plant to remove large debris
– Influent pumps: transport incoming waste to the treatment plant
Primary Treatment
– Sedimentation Tank: Remove solids that are heavy and sink to the bottom as well as oil and grease that floats to the surface. • Primary sludge goes through solids treatment process
and liquids do through a different process
Secondary Wastewater Treatment– Aeration tank: Wastewater from the settling tanks flows
into the aeration tank, where microorganisms such as bacteria and protozoa eat material and nutrients, turning organic materials into solids
– Clarifying tank: Solid matter settle and are pumped to solids treatment process or recycled back to aeration tank.
Final Treatment
– Chlorination and contact tank: kill bateria and viruses
– Dechlorination: Remove toxic chlorine from effluent
Water Released to Puget Sound
– Effluent Pump: Transports effluent out to the environment