prEN 12255-15 rev

Wastewater treatment plants - Part 15: Measurement of the oxygen transfer in clean water in aeration tanks of activated sludge plants

Scope

This document specifies the non-steady state measurement of the oxygen transfer rate and the oxygen
transfer efficiency of aeration systems in activated sludge aeration tanks (see EN 12255-6) when filled
with clean water.
NOTE 1 This is known as the clean water test.
NOTE 2 The test method is based on and valid for completely mixed tanks and tanks with evenly distributed aerators or diffusers. In tapered aeration systems and loop reactors, certain conditions shall be fulfilled for the test method to apply, while the uncertainty of the test result is increased. Methods for assessing the validity of the test method and indicating insufficient mixing are given in Section 5. A measurement method for loop reactors not fulfilling the validity conditions is given in Annex A (informative).
NOTE 3 The standard does not cover membrane bioreactors (MBR), moving bed bioreactors (MBBR) or fixed-film bioreactors, though the test methods described herein might be modified to provide meaningful results in such reactors.
NOTE 4 Testing is required as part of conformance evaluation at peak capacity and to establish operating costs at average capacity, unless the Operator determines that the test is not required.