EN12255-15 - SITUATION

Wastewater Treatment is a central topic in Europe. State of Technology are 2-3 stage treatment plants, where the actual cleaning of sewage is done by biological degradation processes.

Of necessity for an effective biological degradation of organic substance is the presence of oxygen. The degradation of organic substances in an aerobic environment (Presence of oxygen in the sewage) ca. 10-20 times more efficient as in an anaerobic environment (absence of oxygen in sewage). An effective aeration of the biological step of the sewage treatment is thus a basic requirement for a trouble-free and efficient operation of a wastewater treatment plant.

Differing Standards
The situation in Europe was for a long time characterized by differing national measurement standards for the determination of oxygen input into sewage. A negative consequence of these national measurement standards were the lacking comparability of measurement values of products and solutions throughout Europe. For example, an aeration installation in Italy would have been able to achieve an oxygen input efficiency of 1,3 kgO2/kWh according to Italian national standard. However, the same installation measured according to German national standard would result in just 1,1 kgO2/kWh.

The comparability of European products and solutions as well as the possibility to calculate internationally standardized measurements by plant installers and planners needed to be facilitated. As a result, a European measurement standard was introduced and transferred into national law by the European member states (e.g. the DIN 12255-15 in Germany).

One Binding Standard
The European standard EN12255-15 is therefore the only binding measurement standards for the determination of oxygen input in aeration basins of municipal and industrial wastewater treatment plants.

Manufacturers of aeration equipment as well as engineers are not yet fully aware of the new EN 12255. Oxygen inputs calculated according to the outdated standards may be significantly higher than the values according to the EN12255. In the worst case, this may lead to under-dimensioned plants and costly rectifications on behalf of the plant installer.

Now the comparability of different products and manufacturers is given if the measurement and calculation of the oxygen transfer is done consistently done according to EN12255-15. Catalogue values should therefore always be critically scrutinized.