- Organic micro-pollutants in wastewater like pharmaceutical residues can harm aquatic life and may contaminate drinking water resources. Common treatment methods like activated sludge are not fully effective at removing these substances. - Additional treatment methods studied include activated carbon, chemical oxidation with ozone or chlorine dioxide, and these can more effectively remove substances like ibuprofen, diclofenac, and ethinylestradiol. - However, widespread implementation of additional treatment across sewage plants in Switzerland is estimated to cost over 1.2 billion Swiss francs initially and 130 million francs annually, so costs may be prohibitive for full-scale application.