Improved removal of micropollutants and pathogens from municipal wastewater using a pilot-scale hybrid system combining powdered activated carbon and ultrafiltration

Organic micropollutants (OMPs) such as pharmaceuticals, pesticides and industrial chemicals are not sufficiently removed in conventional wastewater treatment plants, resulting in a constant discharge into surface waters and causing risks to the aquatic environment. To contribute to improving OMP removal from municipal wastewater, we tested a hybrid technical system integrating powdered activated carbon (PAC) with downstream ultrafiltration (UF). The focus hereby lies on investigating the OMP removal performance of PAC-UF systems under stable plant operation and the retention efficiency of pathogens, antibiotic-resistant bacteria, genes and viruses. We conducted laboratory experiments and semi-industrial pilot tests to evaluate the performance of the system and determine its suitability for practical implementation. Our results indicate a high level of consistency between laboratory and semi-industrial pilot outcomes, with ultrafine PAC demonstrating significantly enhanced OMP removal efficiency (≥80–95 % removal for selected micropollutants) compared to conventional PAC (60–80 %). Process stability was achieved with both PAC types without significant operational drawbacks, which indicates that optimization of PAC properties, rather than major process redesign, can yield substantial performance gains. The hybrid PAC-UF system provided a robust barrier against pathogens, achieving substantial bacterial log reductions (>3 log removal for E. coli) and effectively retaining antibiotic-resistant bacteria, antibiotic-resistance genes, and viruses. E. coli concentrations met EU regulatory class A water quality standards for agricultural irrigation (<10 CFU/100 mL). Our findings demonstrate the technical feasibility and operational robustness of the PAC-UF system at different scales, indicating its suitability for large-scale municipal wastewater treatment.