Abstract: A method of purifying waste water biologically, in which at least one biological reaction is performed in at least one biological reactor containing microorganisms in activated sludge, and the waste water is separated from the activated sludge in a clarification basin, with at least a fraction of the activated sludge from said biological reactor being recirculated, wherein, prior to admitting the waste water to be treated into said biological reactor, at least a fraction of the polluting particles in suspension therein are separated out therefrom, the separated polluting particles are sent to a sludge activation reactor that is separate and disposed in parallel, the separating polluting particles are used as the main substrate for the development of microorganisms in strict aerobiosis, and the superactivated sludge obtained in this way is injected into the biological reactor(s).

Abstract: Apparatus for the separation of the liquid phase of a solid-liquid suspension, in which the suspension previously thickened is disposed between two endless filtration bands and is subjected to pressure by a presser module to which is imparted a reciprocating motion, includes at least two tight enclosures, juxtaposed and disposed parallel with respect to each other. Each enclosure is provided with an inflatable membrane providing filtration pressure.