Removal of organic micropollutants in wastewater

At present, the main task of municipal wastewater treatment systems is to collect and treat wastewater to prevent the spread of infection and eutrophication. More and more studies show that organic micropollutants, such as pharmaceutical residues, hygiene products, hormones, industrial chemicals, pesticides and other substances, can give rise to undesirable biological effects in aquatic environments.

Several of these substances end up in watercourses, lakes and the sea via water from wastewater treatment plants. Only a few substances are partially degraded at today’s wastewater treatment plants. In order to remove a significant part of these substances, other technical solutions need to be installed than those available at the plants today.

Technical solutions

Technical solutions such as ozonation and dosing of or filtration through activated carbon, for decomposition or adsorption of the micropollutants, have been installed at a few wastewater treatment plants around the world. We need to know more about the technology’s efficiency with regard to the reduction of micropollutants, energy use and resource consumption at our owner companies’ treatment plants, as well as which substances should be prioritized and why.

There are currently no requirements for Swedish treatment plants to introduce treatment from organic micropollutants, but this may occur within a 10-15 year period. A few wastewater treatment plants in Sweden have introduced treatment and the expansion is promoted by investment grants from the Swedish Environmental Protection Agency to reduce society’s emissions of pharmaceutical residues to the aquatic environment.

Purpose

The purpose of this focus area is to find, describe and develop suitable solutions for treatment from organic micropollutants in wastewater at the owner companies’ current or future wastewater treatment plants.

What does SWR do connected to this focus area?

The overall goals for the focus area are to

Study the reduction of various micropollutants with the help of ozonation and activated carbon.
Develop dimensioning criteria and control strategies for efficient use and reduced quantity requirements for ozone and activated carbon.
Develop finishing steps for ozonation.
Study granular activated carbon bed volumes with different pre-treatments.
Study the reducing capacity of different biological purification processes.
Study how the effect of by-products and transformation products affects the choice of treatment method.

To achieve the purpose and the overall goals, we do, among other things

Implementation of a knowledge compilation of separation methods that are applied in full scale.
Carry out pilot tests at various wastewater treatment plants.
Perform lab tests.
Collaboration with laboratories with good experience of analysis of micropollutants.
Utilizes scintillation as an analysis method for the decomposition of micropollutants.
Make preliminary cost estimates.
Close collaborations with technology suppliers.

What knowledge has SWR contributed to?

We have concluded that it is possible to add powdered activated carbon to a nitrifying biofilm on moving support material (MBBR) without affecting the nitrification.

Objectives of the focus area

By 2025, we should know:

whether a specific wastewater treatment plant should choose ozonation, activated carbon or a combination of these as a treatment process
and how the controlling of an ozonation plant should look like

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