Sewage is treated in municipal wastewater treatment plants using mechanical, biological and chemical processes. After treatment, however, many micropollutants such as pharmaceutical residues, hormones and pesticides are still present that cannot be completely removed. Micropollutant removal describes an additional process to eliminate these micropollutants and conserve natural bodies of water by preventing micropollutants from entering them.

Micropollutant removal is a process for cleansing sewage of micropollutants that cannot be removed by municipal wastewater treatment plants. Various technologies are used, such as ozone treatment or activated carbon filtration, or a combination of processes. Ozone treatment involves treating sewage with ozone to oxidise micropollutants and modify them to neutralise their harmful effects.

Activated carbon adsorbs micropollutants to remove them from sewage.

A distinction is made between powdered activated carbon (PAC), which can be added in a contact tank, and granular activated carbon (GAC), which flows through a fixed-bed reactor and adsorbs the pollutants. In the case of PAC, the fine activated carbon has to be removed from the system again later. Combined with membrane bioreactors, this is a very efficient method: The membrane filters completely retain the superfine PAC particles loaded with micropollutants, while the water is filtered through the membrane. This combination of processes also makes it possible to remove antibiotic-resistant bacteria and micro- and nanoplastics almost completely.

The goal of micropollutant removal is to remove harmful micropollutants from the water cycle to prevent them from contaminating the environment. After cleaning, the sewage has a very high quality, making it suitable for reuse in industry or agriculture, for example. Micropollutant removal is an important contributor to environmental protection and sustainable water usage.

A wide range of micropollutants – including pharmaceutical residues, hormones, pesticides, chemicals and other persistent organic compounds – can be removed at this stage of sewage treatment.

Sewage can contain micropollutants from a variety of sources, most of which are of human origin. Even at low concentrations, they can be harmful to the environment and human health. Micropollutants can accumulate not only in bodies of water and the soil, but also in organisms, which introduces them to the food chain, resulting in the potential for long-term harm. Certain micropollutants are harmful to both human and animal health, as they can affect an organism’s hormone balance or even have carcinogenic and toxic effects. Sewage and water treatment are therefore important measures to remove micropollutants from sewage and thus protect the environment and human and animal health. Micropollutant removal in the context of sewage treatment is an important contributor to the elimination of micropollutants and to sustainable water usage.