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Media processes in wastewater treatment are predominantly aerobic, but can be anaerobic. They are fixed film in terms of their biological process configuration, the media providing support for the biofilm.
Examples of aerobic media processes include BAFs, MABRs, MBBRs, RBCs, SAFs, and IFAS, where the IFAS is a combined a fixed film and suspended growth process.
Media processes are those which use a material which provides a significant surface area for biofilm growth. The media can either be fixed or agitated, and air provided from ambient air or from bubbling air through the reactor using a blower and aerators.
Tricking filters (TFs) and rotating biological contactors (RBCs) are examples of fixed film processes. They employ passive aeration: oxygen from air absorbs into the water without the use of pumping.
Both processes, and TFs in particular, are established biological treatment processes in the treatment of municipal wastewaters.
Submerged aerated filters (SAFs) and biological aerated filters (BAFs) are both 'fixed-film' media-based biological treatment processes using packed media beds which support a biofilm.
They are similar in design, the key difference being in the method of removal of the biomass.
The integrated fixed-film activated sludge (IFAS) process and the moving bed bioreactor (MBBR) are both examples of technologies using media agitated with air bubbles. They are similar in configuration, the difference being the recirculation of sludge for the IFAS.
An MABR is an example of a ‘fixed film’ process where the membrane is used both as an aerator and a base for the biofilm. This contrasts with a purely suspended growth process, i.e. one based on activated sludge, like an MBR which also uses a membrane but for solids separation rather than aeration.
The upflow anaerobic sludge blanket reactor (UASB) is an example of an anaerobic wastewater treament process. It relies on the formation of highly settleable granular aggregates through which the water flows, providing filtration and biological treatment.
