O₂ Guarantee and Operating Requirements

The O₂ input and yield values to be specified by the bidder in the bill of quantities are bindingly guaranteed and will be measured and evaluated in accordance with the current ATV guideline M 209 “Measurement of Oxygen Transfer by Aeration Devices in Activated Sludge Plants in Clean Water and Activated Sludge.” The clean water test procedure shall be used, which may involve service or wastewater (α = 0.99).

To ensure efficient and homogeneous mixing, flow resistances in the form of floor crosses or similar structures shall be installed on the tank bottom and/or sidewalls if necessary. A permanently deposit-free operation must be ensured.

Due to the risk of thin sludge and fine aerosol formation, aerator speeds above 90 rpm and peripheral velocities above 6 m/s are not permitted. Direct-drive high-speed units are not allowed. The average circulation velocity of the tank contents must be at least 0.3 m/s.

Aerator Operation and Measures

The bidder guarantees smooth aerator operation without excessive wave formation.
Since “standing” waves may occur due to interference within the given tank geometry, the bidder shall implement appropriate countermeasures, which are to be described below.