Removal of organic micropollutants in granular activated carbon filters – review of long-term and full-scale experiences from municipal wastewater treatment

ABSTRACT The abstract shows a number of papers with the top one having a headline indicating that this is a review of large-scale granular activated carbon filtration. There is a looking glass zooming in on a text saying that this focusing on the breakthrough of indicators. To the right of the papers, there is a picture of a document, the revised Urban Wastewater Treatment Directive. Finally, another step to the right, there are a few breakthrough curves displayed. Granular activated carbon (GAC) filtration is increasingly used for quaternary treatment of municipal wastewater to remove organic micropollutants, in line with the revised EU Urban Wastewater Treatment Directive (Directive (EU) 2024/3019). This review compiles and synthesises available, peer-reviewed, and long-term pilot- and full-scale studies and, in contrast to previous reviews, particularly addresses breakthrough of Urban Wastewater Treatment Directive (UWWTD) relevant indicator compounds in relation to operational lifespan and regulatory compliance. Most studies were conducted at pilot scale, with considerable variation in empty bed contact time, filtration rate, and GAC type. Breakthrough of indicator compounds varied widely, but citalopram, metoprolol, benzotriazole, and methylbenzotriazole generally showed relatively late breakthrough, indicating potential for longer filter lifespan, whereas candesartan and irbesartan more often showed early breakthrough. The available data further indicate that the selection of indicator compounds strongly affects the operational lifespan over which compliance with the UWWTD may be maintained. However, the limited number of long-term full-scale studies and the large variability in pre-treatment, filter design, carbon type, and operating conditions prevent robust quantitative assessment of these relationships. The findings highlight the need for more large-scale, long-term studies using a systematic evaluation framework to support the effective implementation of GAC filtration for UWWTD compliance.