KWR rapport - KWR 2022.090

Fate of Organic Micropollutants in Activated Sludge Systems - Work package 1 report TKI Belissima


Nowadays organic micropollutants (OMP) concentrations have been reported in all environmental components namely water, soil an air. Existing wastewater treatment plants WWTPs were not designed to remove OMPs, nevertheless they do achieve a partial removal. As a point source of contamination, as opposed to a diffuse source, WWTPs offer an unique opportunity to retain these contaminants before reaching the aquatic environment. Overall, the removal of OMPs in WWTPs is not fully understood. It known that it is time, substance and location dependent. A fraction of the OMPs is already being removed in existing WWTPs and removal can be enhanced by installing advanced treatment, also designated in this context as post-treatment. However, the design and operation of the advanced treatment is relying on the effluent being produced by the previous WWTP treatment levels. The operation and performance of existing WWTP treatment levels has an effect on the OMP removal, which is often overlooked.
In this TKI project we focus on 11 OMPs indicators proposed by the Ministerie van Infrastructuur en Waterstaat (I&W), namely 4-5 methylbenzotriazole, benzotriazole, carbamazepine, clarithromycin, diclofenac, hydrochlorothiazide, metoprolol, propranolol, sotalol, sulfamethoxazole and trimethoprim. Currently, in the Netherlands, the municipal wastewater discharge limits do not include OMP discharge restrictions. However, there is the ambition to obtain a minimal removal of 70% of the I&W indicators, from influent to effluent.
In the TKI project Belissima we aim to improve the OMP removal in conventional activated sludge systems (CAS) and advanced treatment, by model development and experimental validation. The project will perform lab tests, WWTP monitoring and post-treatment pilot tests, to support the modelling exercise. The obtained combined model enables optimization studies, aiming for improvement of the effluent quality and savings on operational costs. In this report, we focus on the OMP removal taking place at the conventional activated sludge (CAS) system. The research questions addressed in this report are the following: which OMPs are being removed/transformed in CAS systems and to which degree?; what are the relevant removal mechanisms for OMP removal in CAS?; what are relevant parameters in CAS systems to improve OMP removal?. Furthermore, the report deals with the WWTP selection for this TKI project, which be object of research and modeling exercises. Additionally, the models to apply in the CAS are also addressed. The report is a literature review of consolidated knowledge, with data provided by the water authorities taking part in this TKI project. A second review of TKI Belissima deals with removal of OMPs in
post-treatment technologies.

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