- Headworks The door to the treatment process where contaminants larger than 3/4" in diameter are removed.
- Screenhouse Grit removal and screening devices are installed here.
- Clarifier A large, circular or rectangular tank that separates solids from the waste stream by settling or flotation.
- Flights Slats that move along the bottom or surface of a rectangular clarifier to transport settled or floating material to removal points.
- Skimmers A device that removes grease or scum from the surface of wastewater in a clarifier or tank.
- Aeration Tank A tank normally associated with secondary treatment where air is injected to provide oxygen for microorganisms and to bring them into contact with wastewater through the mixing action.
- Blowers Low pressure air compressors that inject air into the aeration tank.
- Anoxic Selector The section of an aeration tank where oxygen is available in a combined form rather than as dissolved O2 to select out undesirable types of bacteria.
- Anaerobic Digester A closed vessel where solids, or sludges, produced by other treatment processes are stabilized through a biological process which takes place in the absence of oxygen.
- Thickener Equipment or process that increases the concentration of solids in sludge after gravity sedimentation.
- Biosolids Treated wastewater sludges that meet stringent quality control standards.
- Suspended Solids Insoluble solids that either float on the surface of or are in suspension in wastewater or other liquids.
- Return Activated Sludge (RAS) Sludge that is recycled between secondary clarifiers and aeration tanks to maintain an active biomass for secondary treatment.
- Thickened Waste Activated Sludge (TWAS) Solids removed from the activated sludge process and passed through a thickening process or thickening device.
1120 SW 5th Avenue, Room 1000, Portland, OR 97204