Chronic Low Dissolved Oxygen
DO consistently reads below setpoint despite blowers running at or near capacity.
Symptoms: DO probes reading below 1.0–1.5 mg/L basin-wide, blowers running at high output with little improvement, filamentous organisms beginning to appear.
Probable Causes: organic overload exceeding aeration capacity, fouled or damaged diffusers reducing transfer efficiency, undersized or malfunctioning blowers, or a miscalibrated DO probe reading falsely low.
Troubleshooting Steps: 1) Verify probe calibration first — a fouled or aging probe is a common false alarm. 2) Check blower output and inlet filters for restriction. 3) Inspect diffusers for uneven bubble patterns indicating fouling or membrane damage. 4) If loading has genuinely increased, evaluate whether equalization or load balancing across basins is needed rather than just running blowers harder.
The industry's most useful newsletter, straight from the plant floor.
One email. No fluff. New lessons, equipment breakdowns, and process control notes, delivered when there's something worth reading.