| | 1. Scope of Application:
(1) Activated sludge treatment for municipal sewage and various industrial wastewater.
(2) When the efficiency of an existing aeration tank is low, switching to this aerator can enhance treatment capacity and effectiveness.
(3) Can be used as a pre-aerator in sewage regulation tanks to prevent sedimentation of large particles and remove some organic substances.
(4) Suitable for aeration in heavily polluted natural ponds and rivers for water purification.
2. Aerator Specifications and Design Parameters: | Aerator Type | Specification
(mm) | Material | Applicable Water Depth
(m) | Service Area per Aerator (m2) | Air Requirement per Aerator
(m3/min) | Oxygen Transfer Efficiency
(%) | Power Efficiency
(kg O2/kWh) | Resistance
(mm
Water Column) | Single Helix Aerator | ф300×1830
ф300L=300 | Fiberglass | 3.0～8.0 | 3～5 | 0.5～1.0 | 7.4～10 | 2.0～2.4 | ∠250 | Double Helix Aerator | ф315×1200
Two Helical Holes ф150 | Fiberglass | 3.0～8.0 | 3～6 | 0.5～1.0 | 9～10.5 | 2.0～2.5 | ∠250 | Double Helix Aerator | ф420×1740
Two Helical Holes ф200 | Fiberglass | 3.5～8.0 | 4～8 | 0.5～1.3 | 9.5～11.0 | 2.0～2.5 | ∠250 | Triple Helix Aerator | ф420×1740
Three Helical Holes ф185 | Fiberglass | 3.5～8.0 | 4～8 | 0.5～1.3 | 10～12 | 2.0～2.6 | ∠250 |
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| 3. Key Design Points:
(1) Fixed spiral aerators are widely used in activated sludge processes in China, suitable for plug-flow and completely mixed aeration tanks, with generally better performance in plug-flow operation. They can also be used for pre-aeration in regulation tanks to prevent sedimentation of large particles.
(2) To improve oxygen transfer efficiency, the actual water depth of the aeration tank should preferably be above 4.0 meters. To save land and reduce power costs, a draft tube can be added at the bottom of the aerator to enhance sludge recirculation and lifting. The draft tube height can be 0.5～1.0 meters; if experimental data is available, it can be extended further. The suction port of the draft tube should be as close as possible to the tank bottom, typically 250～300 mm. For shallower regulation and aeration tanks (2.5～3.0 meters), the ф315 or ф420 two-section double helix aerators can be selected.
(3) Service area per aerator: Single helix: 3-5 m2; ф315 double helix: 3-6 m2; ф420 double helix and triple helix: 4-8 m2 (typically 6-8 m2 for municipal sewage, 4-6 m2 for industrial wastewater). Distance from tank wall: 1-1.5 meters.
Number of aerators: Determined based on factors such as aeration tank depth, effective volume, and air volume.
(4) Air requirement per aerator: 0.5-1.3 m3/min, calculated based on BOD5 content in the influent. Typically, municipal sewage requires 0.5-1.0 m3/min per aerator, while industrial wastewater requires 0.7-1.3 m3/min per aerator. Aerator resistance varies with air volume but should not exceed 250 mm water column. Blower pressure can be selected based on the reference table.
(5) Air pipe design should form a loop network, with each branch pipe preferably having two valves for air volume adjustment. Design velocities: main pipe 10-15 m/s, branch pipe 5 m/s.
(6) To prevent activated sludge deposition and pipe clogging in air distribution pipes, a 90° elbow can be added at the end of the distribution pipe, with a small hole (diameter ф10 mm) drilled at the top facing the tank bottom to discharge sediments. | | Reference Table for Water Depth and Blower Pressure: | Water Depth (m) | Blower Pressure (mm Water Column) | Remarks | Without Draft Tube | With 0.5m Draft Tube | With 1.0m Draft Tube | 2.5～3.0 | 3000 | 3500 | 3000 | Can select ф315 or ф420
two-section double helix aerator | 4.0 | 4500 | 4000 | 3500 | | 4.5 | 5000 | 4500 | 4000 | | 5.0 | 5500 | 5000 | 4500 | | 6.0 | 6500 | 6000 | 5500 | | 7.0 | 7500 | 7000 | 6500 | | 8.0 | 8500 | 8000 | 7500 |
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