The use of powdered activated carbon (PAC) for organic micropollutant (OMP) removal from municipal wastewater has been state of the art for more than 15 years. With the new Urban Wastewater Treatment Directive in the European Union, OMP removal will become mandatory across the entire region in the upcoming years. In addition to OMP, per- and polyfluoroalkyl substances (PFAS) are also becoming a focus in the water treatment sector. Given the growing importance of CO₂, space, and resource efficiency, more efficient processes are needed. With respect to adsorbent-based technologies, reducing the particle diameter leads to a further increase in adsorbent efficiency. Faster kinetics and a more efficient utilization of the adsorbent allow for a reduction of contact time and dosage, thereby contributing to a reduced CO₂, space and resource footprint. This study evaluates two advanced filtration systems using carbon-based micro-adsorbents (d₅₀ ~ 1 – 2 µm), each designed for distinct treatment scenarios.

The first system sets micro-adsorbents with Pile Cloth Media Filtration (PCMF) for high-flow applications with low OMP or PFAS contaminant concentrations (see Figure 1 (a), such as municipal wastewater (Kirchen et al., 2025) or stormwater. In pilot tests, the micro-adsorbents were dosed together with iron-based coagulant to enhance floc formation. The mixture passed through a flocculation reactor with hydraulic retention times between 0.5 and 10 minutes, followed by separation in the PCMF unit. Samples were collected before and after PCMF, and analyzed for total suspended solids, turbidity, UV absorbance at 254 nm, dissolved organic carbon, OMP, PFAS, phosphorus fractions, and residual carbon-based micro-adsorbents.

Results showed that proportional dosing of ferric ions relative to micro-adsorbents and thorough mixing into the process stream were crucial for [...].

Suboptimal Fe(III)-to-adsorbent ratios or inadequate mixing led to micro-adsorbent residuals in the effluent. Homogeneous mixing ensured [...] and minimal residuals in all tested matrices. By dosing less than [...] mg/L of micro-adsorbents, more than 80 % of OMPs were removed, while residual micro-adsorbents in the effluent remained below [...] mg/L, corresponding to over 98 % removal...