Integrated fixed film activated sludge (IFAS) is a relatively new technology that describes any suspended growth system that incorporates an attached growth media within the suspended growth reactor. Biofilm carriers are generally divided in ‘dispersed media’ or ‘fixed media’. This technique, used in highly developed wastewater treatment plants, can be used as an upgrade for existing facilities or can be constructed newly. The design needs expert knowledge and the system must be operated by skilled labourers.