The common misconceptions in adjusting the air volume of aeration equipment are listed as follows:
I. Cognitive Misconceptions
Fixed parameters without adjustment
The system operates continuously with the initially set aeration air volume, without dynamic adjustment according to changes in influent load, water temperature and mixed liquor suspended solids (MLSS), which easily leads to dissolved oxygen (DO) imbalance.
Blind pursuit of high dissolved oxygen
It is mistakenly believed that higher DO brings better treatment performance. Maintaining DO above 4 mg/L for a long time will cause sludge aging and push up energy consumption by more than 30%.
Single-point data representing overall conditions
The aeration volume of the entire tank is adjusted merely based on readings from a single DO probe, ignoring load differences in different zones of the aeration tank and resulting in local oxygen deficiency.
II. Operational Misconceptions
Reliance on valve throttling for flow regulation
Airflow is controlled by partially closing branch aeration valves instead of prioritizing blower VFD adjustment. This causes waste of pipeline pressure and drastically reduces blower operating efficiency.
Full operation of all aeration equipment
All aerators remain fully open during low-load periods without switching off partial aeration units to regulate air volume, leading to an excessively high proportion of ineffective aeration.
Neglect of equipment clogging impacts
Regular inspection for scaling and clogging of aeration membranes is omitted. Adjustments are still carried out according to original parameters, while the actual effective aeration capacity is far below the set value, resulting in substandard treatment effect.
III. Operation & Maintenance Misconceptions
Long-term lack of sensor calibration
DO sensors accumulate sludge and suffer signal drift. Aeration adjustment becomes completely inaccurate if calibration is not performed when data deviation exceeds 1 mg/L.
Improper emergency handling under extreme working conditions
When the influent load rises sharply, operators only temporarily increase aeration volume without synchronous adjustment of return sludge ratio, failing to rapidly restore system stability.
No parameter adjustment in low winter temperatures
When air temperature drops below 0 °C, the water level inside the tank is not maintained at 1.5–2 m as specified, and aeration is operated under normal-temperature parameters, which may cause frost damage and failure of aeration equipment.