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Scoop: wastewater treatment plant removes micropollutants

The well-being of ecosystems and humans directly depends on the quality of our surface water. Clean waterways are indispensable for drinking water, recreation, and biodiversity. Given the increasing concerns about micropollutants – think of residues from medicines, pesticides, and other harmful substances – improving our water treatment systems is crucial.

At Aquafin’s wastewater treatment plant (WWTP) in Aartselaar, the first full-scale tertiary facility in Flanders has been installed. It removes micropollutants from the effluent (purified wastewater) of a classic biological water treatment plant. Micropollutants are indeed difficult to break down and can accumulate. Currently, the disc filters have been put into operation, and the full start-up of the facility is planned for later.

Sweco was responsible for the feasibility study, preliminary design, permit application, preparation of tender documents, and execution supervision, and managed the disciplines of process design, electromechanics, civil engineering, electricity, automation, and infrastructure.

Innovative pilot project in Flanders

Through the Interreg project ‘Schone Waterlopen door O3G’, Ozonation (O3) in combination with Granular Activated Carbon (GAC) is being used at WWTPs. This innovative, efficient, and cost-effective post-treatment technique aims to improve the surface water quality in Flanders and the Netherlands. With ozone, a part of the micropollutants is broken down, and activated carbon adsorbs the remaining micropollutants. In this way, the water is made as pure as possible.

The WWTP in Aartselaar serves as a pilot project for Flanders. The installation or post-treatment consists of disc filters to remove the remaining suspended solids, an ozonation reactor to oxidize and break down the micropollutants, and then a final treatment with activated carbon filters. On February 8, 2024, ‘Schone Waterlopen door O3G’, in the presence of Sweco, presented the project in Aartselaar to all involved partners. The program included a tour of the post-treatment where the disc filters were already operational.

Clean water for a greener Europe

The European and Flemish approaches to surface water quality were also discussed, as well as the revision of the European Urban Wastewater Treatment Directive (UWWTD). This directive imposes stricter standards for the removal of nitrogen and phosphorus, introduces new emission standards for micropollutants, and emphasizes a risk-based approach. These measures are intended to reduce environmental impact and promote sustainable water management, which is beneficial for public health.

According to the renewed European water framework directives, which will soon be put to vote, large wastewater treatment facilities (WWTPs, treating the wastewater equivalent of more than 150,000 people) must be equipped with micropollutant treatment by 2045. In Flanders, five more WWTPs qualify. This concretely means that one additional facility must be realized by 2033, another two by 2039, and the last two by 2045. For smaller WWTPs, a risk analysis will be performed to evaluate the necessity of additional post-treatment.