PRO CE S S PAG E Greetings from the FWEA Wastewater Process Committee! This month’s column will highlight the Polk County Utilities Sun Ray Wastewater Treatment Facility, which won the 2021 Earle B. Phelps Award in the secondary category for facilities with a design capacity of less than 3 mgd.
A Visit to the Polk County Utilities Sun Ray Wastewater Treatment Facility: Challenging Influent, Excellent Results
T
Bartt C. Booz
he Sun Ray Wastewater Treatment Facility (WWTF) was recognized in 2021 by the Florida Water Environment Federation (FWEA) as the winner of the Earle B. Phelps Award in the secondary treatment category for its impressive effluent quality and consistency. The award is presented annually to wastewater treatment plants that demonstrate exceptional secondary treatment throughout the year and maintain the highest removal of major pollutioncausing constituents, including total nitrogen. The WWTF has been the recipient of the award in 2019, 2020, and again in 2021. The consistency of the plant’s performance, and the awards it has received, are a testament to Polk County (county) and its dedication and commitment to protecting water resources and the environment.
Facility Overview The WWTF is a 1-miliion-gallon-per-day
(mgd), annual average daily flow (AADF), Type I, two-stage, packaged, extended aeration domestic facility, consisting of three parallel treatment trains that were originally constructed in 1997 and upgraded in 2012. The county identified the need for the 2012 plant expansion due to the growth and waste loadings from the county’s South County Jail, which provides the majority of the flow to the WWTF. Influent wastewater, which currently averages approximately 0.385 mgd, enters the plant through a master influent pump station. This pumps up to an elevated headworks, where an automatic bar screen removes influent screenings. Flow is split between three trains: Trains 1 and 2 consist of two anoxic tanks, two aeration tanks, three secondary clarifiers, four chlorine contact chambers, and two aerobic digesters; and Train 3 consists of a pre-anoxic basin, anoxic/aeration basin, clarifier, digester/holding tank, and chlorine contact basin (one each). Multistage centrifugal blowers provide aeration to the activated sludge process. Sodium hypochlorite is used to provide basic disinfection through an effluent flow-paced control system. Waste sludge is thickened in the digesters to 1.5 to 2 percent through aeration and decanting. The facility also includes a concrete pad for a mobile centrifuge dewatering unit and piping
Multistage centrifugal blowers for aeration, March 2022.
4 May 2022 • Florida Water Resources Journal
to convey centrate to the main influent pump station. Sludge is dewatered to 18 to 20 percent solids before being hauled to the county’s north central landfill for disposal. Following disinfection, effluent from the chlorine contact basins flows to an effluent splitter box and an effluent pump station wet well, where flow is distributed to one of three rapid infiltration basins (RIBs); one RIB is onsite at the plant, and the other two are remote. The onsite RIB is a four-cell, 4.02-acre parcel with a capacity of 0.098 mgd. The offsite RIBs include the Prine RIB, with a 0.650-mgd capacity, and the Hopson Road RIB, with a capacity of 0.350 mgd. Table 1 summarizes the typical plant loadings and effluent quality from January to December 2021. Polk County Utilities (PCU) uses a computerized maintenance management system (CMMS), called Hach JobCal, to automatically generate preventive maintenance work orders and document corrective work that has been completed. This program is used by the operations team, trades helpers, mechanics, and electricians. The storage of information allows for easy access by all stakeholders. Preventive maintenance is Continued on page 6
Master influent pump station, March 2022.
