O3-STEP®: successfully scaled-up pilot using innovative technology
The O3-STEP® filter is an innovative technology that allows water authorities to remove nutrients, micro-contaminants and suspended solids in a cost-effective and sustainable manner in order to comply with the Water Framework Directive (WFD) and future EU Directives for urban wastewater. O3-STEP® was successfully tested at WWTP Horstermeer during a pilot study in 2022. Following the pilot, the filter concept has now been implemented on a full scale at Horstermeer and it is being designed for the Amstelveen WWTP.
Witteveen+Bos used its expertise in the pilot to translate the client’s requirements and wishes into a tailor-made approach. Micro-contaminants are highly location dependent, so technical specifications can vary from treatment plant to treatment plant. Therefore, we consider which configuration is most appropriate for each treatment plant.
New configuration
The O3-STEP® filter adds additional ozone treatment to the 1-STEP® filter, a proven method to remove nitrogen, phosphorus and suspended solids. Although the latter filter was initially also effective in removing micro-contaminants, its efficiency decreased over time. By adding a low dose of ozone prior to the 1-STEP® filter, this removal efficiency is maintained for a much longer time. This results in lower operating costs and reduced carbon emissions.
Complement
Both steps in the treatment process complement each other perfectly: ozone oxidises certain micro-contaminants while activated carbon removes other (micro-)contaminants through adsorption and biodegradation. In addition, any oxidative by-products due to ozonation, such as bromate and oxidative stress, are successfully broken down in the downstream 1-STEP® filter. As a result, a long-term (at least three years) removal efficiency of more than 80% is achieved without the discharge of harmful by-products.
Approach to micro-contaminants
The presence of micro-contaminants in the aquatic environment is receiving increasing attention worldwide. Micro-contaminants are substances (such as pesticides, pharmaceutical residues, cosmetics and industrial chemicals), of which low concentrations in the surface water can be harmful to the environment and human health. The pilot study was part of the Innovation Programme Micro-contaminants from Wastewater (IPMW) of the Foundation for Applied Water Research (STOWA). This is a programme of the Ministry of Infrastructure and Water Management (I&W) to encourage water managers, among others, to remove micro-contaminants and support them in conducting research in this field.
The pilot study O3-STEP® was conducted on behalf of the Amstel, Gooi and Vecht (AGV) Water Authority, in collaboration with Waternet, Nijhuis Saur Industries, Delft University of Technology, Norit Activated Carbon and Witteveen+Bos.
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