TULSA NORTHSIDE WWTP CLASS “A” BIOSOLIDS AND DIGESTION ENHANCEMENTS

The City of Tulsa Northside Wastewater Treatment Plant (WWTP) is an advanced secondary plant permitted for a flow of 42.6 million gallons per day (MGD), while currently treating approximately 31 MGD. Treatment facilities include primary clarifiers, activated sludge units (aeration and final clarifiers), and chlorination. Primary solids are thickened in the primary clarifiers, and waste activated sludge (WAS) is thickened in dissolved air flotation thickeners prior to digestion. Thickened solids are anaerobically digested to produce Class B biosolids. Biosolids are stored in unaerated lagoons that are periodically dredged, and biosolids are land applied onto local agricultural land. There are four existing digesters at the plant and a gas storage sphere. Two digesters are in operation and two have been out of service for an extended time period.The City of Tulsa is currently upgrading solids handling and treatment facilities. Goals of the upgrade include cost effectively (1) providing capacity to handle solids when the plant is treating the permitted flow, (2) initially implementing improvements that either produce Class A biosolids or could be later upgraded to produce a Class A biosolids, (3) restoring use of digester gas for digester heating and power generation, (4) providing a system in which odors would not be a chronic problem, and (5) providing a system with limited operational challenges.This project focused on the digesters and how to increase the capacity of the existing anaerobic digestion system. There are two pairs (four total) of anaerobic digesters at the Northside WWTP. Two 80-foot diameter digesters were constructed in 1969, and two additional 90-foot diameter digesters were constructed in 1982. The two older digesters had wooden covers, which have both collapsed, and the digesters are not currently operational.