The Pickaway Correctional Institution’s (PCI) wastewater treatment plant has seen an increase in flow due the regionalization of the plant to serve the prison. The expansion accommodated an increase in daily wastewater flow from 1.4 to 2.4 MGD.
In the course of preliminary planning, the Ohio EPA reviewed TMDLs (Total Maximum Daily Loads) on the receiving steam, the Big Darby Creek. The expectations were lower ammonia, suspended solids and CBOD limits and potentially total nitrogen and phosphorus limits. This prompted a design change to provide tertiary treatment as well as increased capacity.
The PCI WWTP is an extended aeration secondary treatment facility using oxidation ditches. The proposed expansion included the following improvements: Hydraulic expansion to accommodate peak wet weather events to 6.3 mgd; influent headworks improvements to provide fine screening, grit removal grease removal and grit, grease and screenings washing and compacting; retrofitting existing final clarifiers as denitrification tanks ahead of the oxidation ditches; mixed liquor/return activated sludge recycle system; new final clarification; tertiary disc filters; ultraviolet disinfection; post aeration; plant metering and instrumentation; jet aeration system upgrade for the aerobic digesters; two meter belt filter press dewatering with cake conveyor and dry/liquid polymer feed system; a 120 day dry cake storage building.