English to Italian Law/Patents Engineering (general) wastewater treatment

Cari colleghi, un suggerimento su come rendere "media" quando compare da solo?

the media is periodically drained of water in order to prevent accumulation of biomass therein and consequent plugging of openings and voids therein.

the method for treatment of nitrified wastewater also includes treating the wastewater in a media based biological water treatment system prior to supplying it to the tank having a layer of biomass supporting media

the system for treatment of nitrified wastewater also includes a media based biological water treatment system operative to treat the wastewater upstream of the tank having a layer of biomass supporting media