FOEN Project "Strategy MicroPoll"

Micropollutants in aquatic systems can be denoted as "new" pollutants. On the one hand there are new substances on the market which only recently enter the environment. On the other hand the modern chemical analytics allow for the determination of "old" compounds in very low concentrations, in the range of micro- to nanograms per liter. Since micropollutants were also detected in drinking water and can have negative effects on aquatic organisms already in lowest concentrations, they are not only in the focus of research but also in the public awareness. Examples of feminization of male fish give rise to concern. Conventional procedures in wastewater treatment plants eliminate parts of micropollutants already today, although they were originally not designed for this. Within the interdisciplinary FOEN-project "Strategy MicroPoll" fundamentals for taking decisions with regard to the following questions shall be acquired:

• Do micropollutants from urban drainage pose a problem for water quality?

• Is the current wastewater treatment sufficient? Are additional treatment steps required?

• Where do measures at the source make sense compared to the short to medium term "end-of-pipe" solutions at wastewater treatment plants?

The environmental engineering department supports the project with the compilation of a national material flux model. The actual state of micropollutant loads from urban drainage in surface waters serves for identifying critical river sections. A further important contribution for the success of the project is being made with the planning and optimization of an additional treatment step in full scale.

Image: Recent calculations identify over 150 discharge points where the dilution factor is smaller than 10 - assumptions: the average dry weather wastewater discharge is 400 liters per inhabitant and day and the discharges in the rivers are interpolated Q₃₄₇-values (data und interpolation method BWG, 2002). The corresponding wastewater treatment plants are of variable size (from 200 to 200'000 natural inhabitants) and treat the wastewater of about 20% of the whole population.