Nutrient removal is an important process in meeting high quality effluent requirements. Excessive levels of nitrogen and phosphorous disrupt the natural environment and can affect the health of water systems. Furthermore, Prattville's wastewater system was projected to reach its capacity as the population of the surrounding area grew.
Evoqua's VertiCel® System was incorporated into Prattville's wastewater treatment system, which included tanks with fine bubble diffusers, to achieve additional capacity and meet nutrient removal requirements. The VertiCel system uses Evoqua's VLR® Vertical Loop Reactors operated in series that allow dissolved oxidation stratification at the front of the process combined with fine bubble tanks at the end of the process to maximize energy efficiency and process flexibility. The VLR reactor tankage is similar to oxidation ditch technology; however, the tanks are flipped on their side with an upper and lower compartment separated by a horizontal baffle.
Prattville's existing treatment plant consisted of three parallel single reactor aeration basins with a capacity of three million gallons per day (MGD) along with three circular clarifiers. The city selected Evoqua's VertiCel Biological Treatment System to expand capacity to 5.7 MGD, while providing the ability to achieve nitrogen and phosphorus removal limits. The VertiCel system was the optimal choice for this upgrade because it allowed the municipality to reuse the existing parallel aeration basins and add fine bubble diffusers.
Engineers of the South worked closely with Evoqua to provide the engineering and design with Brasfield & Gorrie as the general contractors. The project came to Evoqua through its partner Jim House & Associates. Commissioning of the plant took place on August 2019 with a ribbon-cutting ceremony and open house.