SWWTP Digestion Process Expansion Project

The digestion process at the Southerly Wastewater Treatment Plant (SWWTP) currently consists of three acid phase digesters (APD) and six methane phase digesters. This digestion process treats all of the thickened primary sludge (TPS) and a percentage of the thickened waste activated sludge (TWAS) and produces a Class B sludge and digester biogas.

Due to the new Chemically Enhanced Primary Treatment (CEPT) train, being installed on the north end of the plant, the digestion plant will need to be expanded in in order to digest all of the TPS during peak flows. The Digestion Process Expansion projects will provide an additional mesophilic digester (Digester 7), new electrical building, and will retrofit the three acid phase digesters into additional pre-digestion storage and mixing tanks.

The rest of the digestion plant will be upgraded to operationally match the new Digester 7. The five of the existing digesters will have modifications including a standpipe for surface withdraw and recoating of the floating covers. Digester 6 will have the steel cover replaced with a concrete cover and will have a stand pipe installed as well.

Construction is scheduled to begin in early 2022 and will last approximately three years. The construction will be sequenced to maintain as many digesters in service as possible to maximize the beneficial reuse of biosolids.

Financing for this contract is being provided through a below market-rate loan through the OEPA’s Water Pollution Control Loan Fund (WPCLF) Program.

The Ohio EPA has completed a Limited Environmental Review (LER) for this project. View the LER and the letter(PDF, 680KB) of "Notice of Issuance of a Limited Environmental Review and Final Finding of No Significant Impact” to all interested citizens, organizations and government agencies." 

For questions specific to this project please contact Project Manager, Tyler Schweinfurth, P.E. at (614) 645-7758 or gtschweinfurth@columbus.gov