BS EN 12255-7:2026

This document of the EN 12255 series specifies design principles and performance requirements for secondary and tertiary treatment of wastewater in biological fixed-film reactors at wastewater treatment plants for more than 50 PT. Its primary application is for wastewater treatment plants for the treatment of domestic and municipal wastewater. It can also be applied for biodegradable industrial wastewater. Biological fixed film reactors include rotating biological contactors (RBC), biological trickling reactors (BTR), moving bed biological reactors (MBBR), submerged medium reactors (SMR) and submerged media filters (SMF). Membrane bioreactors (MBR) and anaerobic processes are not within the scope. Some of the systems using fixed film bacteria are enhanced activated sludge systems (hybrid systems). For such systems, EN 12255-6 also applies. This document specifies fundamental information about typical systems and does not provide information about all available fixed film systems.