Department Process Engineering

Strategy Micropoll

The Swiss Federal Office for the Environment (FOEN) currently conducts the project Strategy Micropoll in order to develop a strategy to reduce the input of organic micropollutants from domestic wastewater into Swiss surface waters. The project started in 2006 and was finished by the end of 2010. Results from this project led into the development of the VSA-Plattform Verfahrenstechnik Mikroverunreinigungen.

The most important questions are the following:

  • Do micropollutants originating from urban catchments have a negative impact on Swiss surface and groundwater? Which are the most critical substances and which water courses are affected?
  • Is the current technology used for wastewater treatment sufficiently efficient in reducing the input of micropollutants or do we need to upgrade the wastewater treatment plants with additional, advanced treatment steps?
  • How can we measure and assess the impact of micropollutants in surface waters with a minimal effort?

The project is divided in three work packages:

  • Need for action: Assessment of the current situation of Swiss surface waters with respect to selected micropollutants, based on measurements and mass-flux-studies.
  • Exposure assessment: Development of a measurement concept and selection of relevant substances in order to assess the quality of surface waters. Selection of indicator substances, which can be used to assess the efficiency of measures taken to reduce the input of micropollutants.
  • Technical measures: Evaluation of various upgrading technologies for wastewater treatment plants. Evaluation of two full-scale pilot-studies with ozonation of the treated wastewater and various small-scale experiments with addition of powdered activated carbon.

Eawag is strongly integrated in the project „Strategy Micropoll“ and has a leading role in all work packages.

What are micropollutants?

The term “micropollutants” or “trace contaminants” refers to (mostly anthropogenic) substances that are measured in the range of ng/L to µg/L range (1 µg/L corresponds to the amount of 1 kg of sugar in Lake Biel). It summarizes a broad variety of chemicals that are used for various purposes, such as plant and material protection (pesticides, biocides), additives found in consumer products like sun creams or detergents (e.g. UV-filters, corrosion inhibitors), pharmaceuticals (e.g. antibiotics, analgesics, X-ray contrast media) or natural and synthetic hormones (e.g. contraceptives). Some of these substances are highly effective even in very low concentrations and may have adverse effects on aquatic organisms. The most prominent example for such effects is probably the feminization of male fish by endocrine disruptors.

Input pathways and fate in wastewater treatment

There are several input pathways for micropollutants into watercourses. Probably the most important one for pharmaceuticals and hormones is by treated wastewater. Today’s wastewater treatment plants are designed for the removal of organic material and nutrients (nitrogen, phosphorus). However, their removal capacity with respect to the micropollutants was intensely investigated in recent years by various research groups (also by Eawag within the EU-project Poseidon). As the removal capacity of WWTP is not sufficient, upgrading technologies are necessary in order to reduce the input of micropollutants into watercourses from domestic wastewater.

Advanced technologies for micropollutants removal

Several processes have been developed for the removal of micropollutants from drinking water, e.g. activated carbon treatment, nanofiltration, ozonation, advanced oxidation processes, some of which were also investigated at Eawag. Within the project “Strategy Micropoll” various pilot studies are conducted in order to investigate their application in wastewater treatment. The focus of the project lies on technologies that are capable of eliminating a broad range of micropollutants at reasonable costs; namely ozonation and powdered activated carbon (PAC) treatment.

Ozonation is tested in two full-scale experiments at WWTP Regensdorf and WWTP Lausanne (STEP Vidy). The pilot study in Regensdorf was successfully completed in October 2008 while the study in Lausanne started in May 2009. Besides these full-scale experiments three smaller pilot studies with PAC are conducted at Eawag, WWTP Lausanne and WWTP Kloten-Opfikon (supported by laboratory experiments at Eawag).