https://phys.org/news/2018-10-large-amounts-antimicrobial-substances-swedish.html

Marcus Östman shows in the dissertation that many antimicrobial substances are very common in sewage treatment plants and also at high levels. Highest concentrations are found in the sludge, especially of substances known as quaternary ammonium compounds. Treated wastewater effluents contains generally lower levels, but large amounts are still released in total.

At present, there is no legislation to regulate the emissions of these substances from sewage treatment plants. However, new technology is evaluated to address the problem, and in the thesis, Sweden's first full scale ozone treatment plant in Knivsta, as well as an activated carbon test plant, are evaluated.