The role and function of biofilm in biological activated carbon filters for removal of organic micropollutant wastewater

Research Project, 2025 – 2029

The increasing use of chemicals has led to higher levels of organic micropollutants (OMPs) in the water cycle, which negatively affect aquatic ecosystems and human and animal health. Wastewater treatment plants (WWTPs) are significant sources of OMPs, including active substances from pharmaceuticals and personal care ingredients, as well as PFAS. For their removal, adsorption to granular activated carbon (GAC) has emerged as a key process, capable of removing OMPs and transformation products that ozone treatment cannot. Because of the high price of activated carbon, this can be a substantial part of a WWTP budget. The removal occurs not only by adsorption but also by biodegradation in the biofilm that develops on the granule surfaces, which can enhance as well as impair the removal. Despite the incentives to optimise the combined effect, it is currently largely unknown how these two processes interact, but that is what this project focuses on. Laboratory-scale GAC filters will be used to assess how dissolved organic matter and biofilm microbial composition affect OMP removal. By determining the spatial localization of OMPs and their transformation products within the biofilm and GAC matrix, we aim to clarify the role of the biofilm in OMP removal. As a tool for improved understanding, optimized operation and design, a mathematical model that includes both the biodegradation in biofilm and adsorption will be developed and calibrated using data from a pilot-scale GAC filter.