PRO CE S S PAG E Greetings from the FWEA Wastewater Process Committee! This month’s column will highlight the Polk County Northeast Regional Wastewater Treatment Facility, which won the 2021 Earle B. Phelps Award in the advanced secondary category for facilities with a design capacity from 5 million gallons per day (mgd) to less than 10 mgd.
Award-Winning Polk County Northeast Regional Wastewater Treatment Facility: Advanced Treatment Through Operational Efficiency Bartt C. Booz The Northeast Regional Wastewater Treatment Facility (NERWWTF) is the newest, mostsophisticated, and largest of three regional plants currently in Polk County (county). The facility was recognized by the Florida Water Environment Association (FWEA) in 2021 as the Earle B. Phelps Award winner in the advanced secondary category for outstanding nutrient removal, secondary clarification, filtration, and high-level disinfection. The Earle B. Phelps Award is presented annually to wastewater treatment plants that demonstrate exceptional advanced secondary treatment throughout the year and maintain the highest removal of major pollution-causing constituents, such as total nitrogen (TN) and total phosphorous (TP). This award demonstrates the county’s dedication and commitment to protecting the environment and serving the community.
Past Expansion
The original NERWWTF was built in 2001
with a capacity of 3 mgd. Due to the growth in the area and increasing waste loadings, the county identified in 2006 that the NERWWTF needed a significant expansion to 6 mgd due to rapid growth along the Highway 27 corridor. In 2012, construction was completed to expand the facility to 6 mgd, with a build-out capacity of 9 mgd. The expansion included a state-of-the-art biological nutrient removal (BNR)/oxidation ditch treatment facility. Other facility improvements of the 2012 upgrade included automated sequencing for digestion, biosolids dewatering, a supervisory control and data acquisition (SCADA) system operable throughout the plant from tablets, and aquifer recharge.
Current Expansion In 2019, a capacity evaluation of the NERWWTF identified the need to add secondary clarification capacity to the facility to accommodate current and future flows and loading, and address Class 1 reliability requirements. In 2020, the county began construction of two new 100-foot-diameter
Figure 1. View of the Northeast Regional Wastewater Treatment Facility during construction of two new 100-foot-diameter secondary clarifiers (June 2021).
6 December 2021 • Florida Water Resources Journal
secondary clarifiers (Figure 1) to expand the facility’s secondary clarification process from a capacity of 6 to 9 mgd. The project also includes a new return activated sludge/waste activated sludge pumping station, new screenings wash presses (Figure 2) for the existing screening structure, hydraulic improvements, and site stormwater/ drainage improvements. Construction of the project is expected to be complete by June 2022.
Process Overview Influent wastewater is screened with perforated plate mechanical screens at the screening structure before flowing to the BNR basin with flow equalization capability. The existing BNR contains selectable anoxic and aerobic zones, where aeration is accomplished with fine bubble diffusers prior to flowing to one of the two oxidation ditches, also with anoxic and aerobic zones. Following secondary biological treatment, the mixed liquor flows to three secondary clarifiers for settling, return sludge, and waste sludge. Continued on page 6
Figure 2. New screenings wash presses at the screening structure (September 2021).
