Activated Sludge · Aeration and Dissolved Oxygen
How Is Dissolved Oxygen Measured in an Aeration Basin?
A DO probe measures dissolved oxygen at the sensor location. Representative measurement requires the right location, depth, response time, and maintenance. A reading near intense bubbling may not represent the rest of the basin.
Optical probes read oxygen through a light-sensing cap, while membrane probes use a thin membrane over the sensor. Operators should follow the manufacturer's procedures for calibration, verification, membrane or optical-cap care, cleaning, and storage. Fouling, trapped bubbles, damaged components, or poor calibration can create false confidence.
A DO profile is a planned set of readings from several basin locations or depths. Profiles can reveal low-oxygen zones, uneven air distribution, excessive aeration, or a demand pattern that one fixed sensor misses.
Compare portable readings with fixed instruments and process conditions. If values disagree, check both instruments and sampling conditions before making a large aeration change.
Key point: A DO reading near heavy bubbling may not represent the basin. A DO profile can find low-oxygen zones that one sensor misses.
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Activated Sludge Process Control for Wastewater Operators
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