Filtration vessel, in particular an ultrafiltration vessel, for at least partially removing a contaminant from a fluid, the filtration vessel comprising: a vessel body which comprises a tubular section extending along an axial direction of the vessel body, wherein, in use, the axial direction is vertical, wherein the vessel body comprises a first axial end and a second axial end, wherein the second axial end is located opposite with respect to the first axial end along the axial direction and in an upper section of the vessel, a first end cap which is mounted to the first axial end, a supporting plate which is arranged at the second axial end, wherein the supporting plate comprises at least one first through hole, an inlet pipe which is mounted to the first end cap and to the supporting plate, wherein the inlet pipe comprises at least one slot through which the fluid is injectable into an inner volume (Vi) of the vessel body, at least one membrane rod comprising an axial rod end, wherein the membrane rod comprises a plurality of membrane straws, wherein the axial rod end is mounted to the first through hole of the supporting plate such that the membrane rod extends from the supporting plate into the inner volume (Vi), and wherein the membrane rod is formed such that the fluid is injectable from the inner volume (Vi) through a peripheral surface of the membrane rod and through a peripheral surface of the membrane straws into the membrane straws and is further exhaustible through the axial rod end and through the first through hole of the supporting plate, a second end cap which is mounted to the second axial end such that a storage volume (Vs) between the supporting plate and the second end cap is generated, and a ring element which is mounted to the second axial end, wherein the ring element surrounds the supporting plate and forms an edge around the supporting plate such that a liquid is storable inside a volume (Vv) formed by the edge and the supporting plate, the ring element and supporting plate being formed integrally. a vessel body which comprises a tubular section extending along an axial direction of the vessel body, wherein, in use, the axial direction is vertical, wherein the vessel body comprises a first axial end and a second axial end, wherein the second axial end is located opposite with respect to the first axial end along the axial direction and in an upper section of the vessel, a first end cap which is mounted to the first axial end, a supporting plate which is arranged at the second axial end, wherein the supporting plate comprises at least one first through hole, an inlet pipe which is mounted to the first end cap and to the supporting plate, wherein the inlet pipe comprises at least one slot through which the fluid is injectable into an inner volume (Vi) of the vessel body, at least one membrane rod comprising an axial rod end, wherein the membrane rod comprises a plurality of membrane straws, wherein the axial rod end is mounted to the first through hole of the supporting plate such that the membrane rod extends from the supporting plate into the inner volume (Vi), and wherein the membrane rod is formed such that the fluid is injectable from the inner volume (Vi) through a peripheral surface of the membrane rod and through a peripheral surface of the membrane straws into the membrane straws and is further exhaustible through the axial rod end and through the first through hole of the supporting plate, a second end cap which is mounted to the second axial end such that a storage volume (Vs) between the supporting plate and the second end cap is generated, and a ring element which is mounted to the second axial end, wherein the ring element surrounds the supporting plate and forms an edge around the supporting plate such that a liquid is storable inside a volume (Vv) formed by the edge and the supporting plate, the ring element and supporting plate being formed integrally.