Cleaner waterways through ozonation and granular activated carbon

Smart combinations needed

Both the Netherlands and Flanders have conducted extensive research in recent years on the removal of organic micropollutants (OMPs), with ozonation emerging as one of the most effective technologies. One key consideration is the ozone dose applied. High ozone concentrations can lead to the formation of undesirable by-products such as bromate, while also wasting energy in the process. Furthermore, the Netherlands classifies bromate as a substance of very high concern. To achieve high removal efficiency while mitigating adverse effects, ozonation can be smartly combined with activated carbon filtration (adsorption).

Within the Clean Waterways through O3G project, we are investigating how ozonation and a Granular Activated Carbon (GAC) filter can be optimally integrated to achieve an efficient and cost-effective treatment of WWTP effluent. In addition to purification efficiency, we also assess the impact of this technology on ecotoxicity, as well as its implications for treatment costs and the energy and resource consumption of WWTPs.
 

New insights through laboratory, pilot, and full-scale research

This three-year project involves research at various scales. Ghent University has initiated laboratory-scale research while keeping full-scale applications in mind. The team is examining how a pre-treatment step (coarse filtration) can remove ozone scavengers such as nitrite, thereby improving ozone efficiency. Post-treatment of ozonated effluent with activated carbon, in turn, helps remove by-products and persistent micropollutants, providing a comprehensive treatment solution.

To achieve this, UGent is conducting in-depth research on the conditions under which the combination of ozone and activated carbon can be optimally deployed. The team is also developing advanced analytical methods for a wide range of organic micropollutants. Additionally, UGent is investigating whether online surrogate measurements such as UV-VIS absorbance and fluorescence can be used to monitor and control ozone-based treatment processes more efficiently, potentially reducing operational costs by 10 to 20%.

The University of Antwerp is primarily conducting laboratory research on microbial activity within granular activated carbon granules. Their team is exploring whether the lifespan of a filter can be extended by stimulating microbial activity. Typically, it takes time for microorganisms to proliferate to the extent that they contribute to micropollutant removal. Researchers at UAntwerp are studying both the role of bacteria in removing micropollutants and whether pre-treatment with ozone enhances the (biological) degradability of these pollutants. Lastly, UAntwerp is investigating the impact of the treatment train on ecotoxicity in relation to the receiving water.

Both UAntwerp and UGent are closely linking their research to pilot and full-scale installations. Currently, they are already testing with WWTP effluent and GAC filter granules from the WWTP in Aartselaar. One of the two pilot installations at Waterschap De Dommel in the WWTP in Tilburg is in the final stage of the tender process. In parallel, a second pilot installation will be set up using the Microforce++ technology from PureBlue. This latter pilot involves an innovative combination of ozonation, biofiltration, and activated carbon, which has performed well in feasibility studies in terms of CO₂ footprint, modular deployment, and nutrient removal integration. Once operational, these pilot installations will also undergo testing.

Assessing treatment technology via life cycle assessment (LCA)

The evaluation of technologies through Life Cycle Assessment (LCA) is becoming increasingly important. At HZ University of Applied Sciences, researchers are working alongside students to conduct LCAs of the tested technologies using the openLCA software and the Ecoinvent 3.10 database.

They have developed an approach comparable to existing literature in terms of methods (ReCiPe, IPCC, EF) and sources of information. Using the available data, this approach has been applied to assess the full-scale installation of Aquafin in Aartselaar. Given the scale of this installation, the results for CO₂ footprint can be directly compared with those published under the IPMV programme of STOWA, the knowledge centre for Dutch water boards.

As a next step, they will conduct sensitivity analyses for specific parameters based on experiences with the technologies at laboratory scale and possibly also at pilot scale.
 

Advanced modelling: the foundation for technological acceleration

Since 1 January 2025, the revised European Urban Wastewater Directive (EU-UWWD) has been in force. The EU-UWWD imposes stricter requirements on the treatment of urban wastewater. For example, all WWTPs with a load of 150,000 PE or more must be equipped with tertiary treatment (focused on nutrient removal) by 2039, and by 2045, they must also include quaternary treatment (focused on micropollutant removal). The knowledge gained from this Interreg project is therefore highly relevant.

Recognising the importance of knowledge valorisation, AM-Team, as a digital innovator, is focusing on advanced modelling and digitalisation of treatment and production facilities within the water industry. As part of this project, AM-Team will develop models for ozone treatment combined with activated carbon. Their existing AMOZONE model, which predicts micropollutant removal in oxidation processes, will be expanded to include an activated carbon model calibrated with real-world data from Waterschap De Dommel and Aquafin. This refined model will enable optimisation tests that would otherwise be unfeasible. AM-Team will make the enhanced model available worldwide to accelerate the development of these advanced treatment processes.

Project coordinator VITO Kennispunt Water will ensure the effective dissemination of knowledge generated by this project with the support of CAPTURE.

Read more about  Schone Waterlopen door O3G | Interreg Vlaanderen-Nederland