Common Fault Handling Methods for Manganese Sand Filter Aeration Systems
Faults can be categorized and addressed as follows, combining specific operational steps and maintenance points:
I. Inadequate Aeration Performance (Core Fault)
Phenomenon: Excessive iron and manganese in effluent (Fe > 0.3 mg/L, Mn > 0.1 mg/L), dissolved oxygen < 5 mg/L.
Handling Methods:
1.Aeration Device Maintenance
•Clean or replace aerators/injectors (soak in 5% dilute hydrochloric acid for 10 minutes to remove iron/manganese oxide blockages).
•Check blower belt tension (sag ≤ 1–2 cm), clean intake filters, and ensure air flow meets standards (aeration intensity: 2–3 m³/(m²·h)).
2.Water Quality Optimization
•Adjust influent pH to 7.5–8.5 (add lime milk or sodium hydroxide). Extend aeration time to 60 minutes if water temperature < 10°C.
•If organic content in raw water is high, add pre-oxidation (dose sodium hypochlorite at 0.5–1 mg/L).
3.Filter Media Regeneration or Replacement
•For clogged media, perform air washing (12–14 L/(m²·s), 5 minutes) followed by water washing (15 L/(m²·s), 15 minutes). If needed, soak in 1%–2% dilute hydrochloric acid for 15 minutes.
•Replace media if used for >3–5 years or if MnO₂ content < 30% (retain 10% old media to accelerate biofilm formation).
II. Backwash System Faults (Key Link Affecting Aeration)
1.Insufficient Backwash Intensity
•Phenomenon: Media expansion rate < 30%, effluent turbidity > 1 NTU.
•Handling:
•Increase backwash pump head to ≥15 m, ensure valves fully open (opening ≥ 70%), and pipe diameter ≥ DN100 mm.
•For insufficient air wash intensity, replace blower belts or clean impeller dust, and repair air leakage points in aeration pipes (pressure ≥ 0.05 MPa).
2.Uneven Water/Air Distribution
•Phenomenon: Localized media not expanding, effluent containing iron rust particles.
•Handling:
•Shut down and clean water/air distributors (flush blocked holes with high-pressure water; soak in dilute hydrochloric acid if necessary).
•Adjust filter media layer height (deviation ≤ 50 mm) to ensure uniform air/water distribution.
3.Media Loss
•Phenomenon: Backwash effluent carries significant manganese sand; media layer height decreases > 5 cm.
•Handling:
•Reduce backwash intensity (water intensity ≤ 15 L/(m²·s), air intensity ≤ 12 L/(m²·s)).
•Replace damaged water distribution caps (gap ≤ 0.3 mm) and replenish media to design height.
III. Equipment Component Failures (Hardware Issues)
1.Pump/Blower Abnormalities
•Phenomenon: Pump vibration > 0.1 mm or blower abnormal noise.
•Handling:
•Pump: Replenish lithium-based grease (replace quarterly), clean inlet filters (aperture ≤ 2 mm), repair cavitation-damaged impellers.
•Blower: Drain condensate from air tanks, replace worn belts (tension sag: 1–2 cm).
2.Valve Failures
•Phenomenon: Valve jamming or leakage > 10% of rated flow.
•Handling:
•Replace sealing gaskets (EPDM material), clean rust from valve cores.
•For electric valves, calibrate actuator gears to ensure accurate opening feedback.
IV. Seasonal Faults (Environmental Factors)
1.Winter Freezing and Cracking
•Handling: Drain residual water from pipes after backwash; add insulation or electric heating (maintain temperature ≥ 5°C).
2.Summer Algae Clogging
•Handling:
•During backwash, add 0.1% sodium hypochlorite solution (contact for 30 minutes), then rinse twice with clean water.
•Regularly clean aerators (soak monthly in 10% dilute hydrochloric acid) to prevent algae adhesion.
Special Recommendations for Chongqing Dazu Region
If local groundwater iron/manganese content > 5 mg/L:
•Prioritize air compressor aeration (stable air flow) to avoid injector failure due to insufficient water pressure.
•Shorten backwash cycle to once every 5–7 days to prevent media clogging.
•Regularly test raw water pH (add lime milk if pH < 7.5) to ensure manganese oxidation efficiency.
By following the above methods, aeration system faults can be effectively addressed, ensuring stable operation of manganese sand filters.
