A method and apparatus for manufacturing a combined polymeric structure are disclosed. The apparatus includes an extruder body (110), a die (120) configured to receive flowing polymeric material from the extruder body (110) and a motion unit. The die includes a hollow inner die (122), a protecting sleeve (124) located within the inner die (122) and an outer die (125) located at an exit (128) end of the hollow inner die (122). The motion unit is configured to cause bidirectional translational motion of the hollow inner die (122) relative to the outer die (125).

A compressible biomass carrier for use in fluid treatment systems is disclosed. The biomass carrier includes an extruded circumferential mesh-like structure and elongated elements positioned in a space confined by the circumferential mesh-like structure and at least some of the elongated elements are joined to an inner portion of the mesh-like structure.

A tubular casing centered on an axis and a coaxial core mounted rotatably about the axis. An upstream part of the core extends into the casing so that a material flow channel is defined therebetween, which is annular in cross-section and centered on the axis. A downstream part of the core extends outside the casing and is coupled to a motor-drive for driving in rotation is fixedly secured to the casing and coaxially received in the casing so that a passage is delimited therebetween, connecting a central inlet of the casing and an upstream end of the channel. The passage is shaped so that the material advances through the passage forming a flow that diverges from the axis toward the downstream and is distributed around the axis. The male divergent part abuts axially against the upstream part of the core, supporting same and guiding same in rotation.

A nozzle includes a tubular, temperature-controlled outer casing, centered on an axis. For a more compact and efficient design, the nozzle also includes an inner member coaxially arranged inside the outer casing and mounted rotatably about the axis relative to the outer casing, such that a downstream portion of the inner member extends outside the outer casing and engages with a drive motor to rotate about the axis, and such that a channel having an annular cross section and centered on the axis is defined between the outer casing and the inner member. The channel has an upstream end and a downstream end between which the material flows into the channel when it is pushed through the nozzle such that, when the material is pushed through the nozzle, the material moves through the channel from the upstream end to the downstream end whereby the material axially exits the channel.

A nozzle includes a tubular, temperature-controlled outer casing, centered on an axis. For a more compact and efficient design, the nozzle also includes an inner member coaxially arranged inside the outer casing and mounted rotatably about the axis relative to the outer casing, such that a downstream portion of the inner member extends outside the outer casing and engages with a drive motor to rotate about the axis, and such that a channel having an annular cross section and centered on the axis is defined between the outer casing and the inner member. The channel has an upstream end and a downstream end between which the material flows into the channel when it is pushed through the nozzle such that, when the material is pushed through the nozzle, the material moves through the channel from the upstream end to the downstream end whereby the material axially exits the channel.