Comparing adsorption stage designs in membrane hybrid processes with powdered activated carbon dosing for advanced wastewater treatment and reuse

Membrane hybrid processes with powdered activated carbon adsorption potentially pose a synergistic option to combine micropollutant removal and advanced wastewater treatment for water reuse. While the individual treatments are known to be effective, literature lacks applied studies of the combined processes in the face of new European regulations. In a 336-day pilot operation, we show that a novel inline-dosing process design is equally capable of reaching these treatment goals as a modified Ulm process design, equipped with ultrafiltration membranes. Both processes, reliably and independently of feed quality, delivered an effluent water quality suitable for water reuse applications, as required by EU 2020/741, Annex I, Table 2, while creating excellent conditions for an energy-efficient downstream UV disinfection (UV-Transmittance improvement by 10–20% points). Both processes were able to remove organic micropollutants to a similar degree. While the inline-dosing process requires no separate contact volume, nor sedimentation volume, it does show slightly weaker effluent quality and filtration performance in the downstream membrane process, which remains in a competitive range around 300 L/(m2 h bar). Hence, both examined process designs pose suitable and reliable options for the intended use case.