How does the AO process control the dissolved oxygen DO level in Tank A
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The dissolved oxygen level in pool O is around 5 mg/L. Since a portion of the water from pool O is recycled to pool A, the dissolved oxygen level in pool A is 2.5 mg/L; clearly, denitrification does not take place there. How can we reduce the dissolved oxygen in Pool A now? Thank you
The dissolved oxygen level in tank A is 2.5 mg/L; denitrification is no longer occurring. It is necessary to reduce the flow rate of the mixed return stream as soon as possible in order to lower the dissolved oxygen level in tank A.
The dissolved oxygen level in Pool A is too high, which in turn affects the increase in dissolved oxygen in Pool O. When the dissolved oxygen level in Pool O is high, that of Pool A also rises, creating a vicious cycle; it is necessary to reduce the aeration volume in Pool O as soon as possible to lower the dissolved oxygen level.
Why is the DO concentration in Pool O so high? Is it excessive airflow, or is the sludge concentration too low or inactive? The air volume is too high; adjust the air volume ； The issue lies with the sludge itself; first, resolve that problem. However, the air flow rate also needs to be adjusted, and it should be restored to its normal level once the sludge concentration or activity returns to normal.
Both problems of excessive air volume and too low sludge concentration exist, right? Prepare the device to mitigate sludge accumulation.
1. Strictly control the DO in Tank O. 2. Adjust the sludge return ratio
As an emergency measure, aeration can be avoided; aeration should only be resumed once the dissolved oxygen level drops below 1. When aeration is used, the amount of air supplied must be controlled so that the dissolved oxygen level does not exceed 2.
Reduce the reflux ratio while lowering the dissolved oxygen concentration in tank O. A gradual increase in intensity can be adopted to keep the dissolved oxygen at the end point at only 2 mg/L.
Gradual aeration is achieved by adjusting the opening degree of the aeration branch pipe valves to reduce the aeration intensity.