NR 811.45(3)(a)(a) Pressure aeration may be used for oxidation purposes. Pressure aeration will not be approved for removal of dissolved gases. NR 811.45(3)(b)(b) Filters following pressure aeration shall be provided with adequate exhaust devices for release of air. NR 811.45(3)(c)(c) Pressure aeration devices shall be designed to cause a thorough mixing of compressed air with the water being treated. NR 811.45(3)(d)(d) Pressure aeration devices shall provide screened and filtered air that is free of obnoxious fumes, dust, dirt, and other contaminants. NR 811.45(3)(e)(e) Air compressors supplying pressure aerators shall be oil-less. NR 811.45(3m)(3m) Packed tower aeration. Packed tower aeration systems shall meet all of the following requirements: NR 811.45(3m)(a)(a) Materials of construction shall meet all of the following requirements: NR 811.45(3m)(a)1.1. The packing material shall be certified by ANSI/NSF standard 61 dated March 15, 2022, which is incorporated by reference. NR 811.45 NoteNote: A copy of ANSI/NSF standard 61 dated March 15, 2022 is available for inspection at the Legislative Reference Bureau and may be obtained for personal use from NSF International, https://www.nsf.org. NR 811.45(3m)(a)2.2. The tower shall be constructed of stainless steel, concrete, or aluminum. NR 811.45(3m)(b)(b) Process design shall meet all of the following requirements: NR 811.45(3m)(b)1.1. Water loading rates shall be in the range from 15 to 30 gallons per minute per square foot. Water loading rates outside of this range may be used if justified to the department by pilot testing under s. NR 811.44. NR 811.45(3m)(b)2.2. The ratio of the packing height to column diameter shall be at least 7:1 for the pilot unit and at least 10:1 for the full-scale tower. The type and size of the packing used in the full-scale unit shall be the same as that used in the pilot study. NR 811.45(3m)(b)3.3. The minimum volumetric air to water ratio at peak water flow shall be 25:1 and the maximum shall be 80:1. Air to water ratios outside of these ranges may be justified to the department by pilot testing under s. NR 811.44. NR 811.45(3m)(c)(c) The water flow system shall meet all of the following requirements: NR 811.45(3m)(c)1.1. Water shall be distributed uniformly at the top of the tower using spray nozzles or orifice-type distributer trays that prevent short circuiting. NR 811.45(3m)(c)2.2. A mist eliminator shall be provided above the water distributor system. NR 811.45(3m)(c)3.3. A side wiper redistribution ring shall be provided at least every 10 feet in order to prevent water channeling along the tower wall and short circuiting. NR 811.45(3m)(c)4.4. Smooth-end sample faucets shall be provided on the influent and effluent piping. NR 811.45(3m)(c)5.5. The effluent sump shall have easy access for inspection and cleaning. NR 811.45(3m)(c)6.6. A pump to waste line shall be provided in the effluent piping to allow for discharge of water and chemicals used to clean the tower. NR 811.45(3m)(c)7.7. The design shall prevent freezing of the influent riser and effluent piping when the unit is not operating. If piping is buried, it shall be maintained under positive pressure higher than the ground surface. NR 811.45(3m)(c)9.9. Include an overflow line that discharges 12 to 24 inches above a splash pad or drainage inlet. Proper drainage shall be provided to prevent flooding of the area. NR 811.45(3m)(c)10.10. Butterfly valves may be used in the water effluent line for better flow control and to minimize air entrainment. NR 811.45(3m)(c)12.12. The water influent pipe shall be supported separately from the tower’s main structural support. NR 811.45(3m)(d)(d) The air flow system shall meet all of the following requirements: NR 811.45(3m)(d)1.1. The air intake and outlet vent shall be protected with a 24-mesh corrosion resistant screen and cover and be accessible for maintenance and inspection.