Filter unit for filtering microparticles and a filter cage for use in a filter unit

1 . A filter cage for use in a filter unit for filtering microparticles from a feed liquid containing microparticles, wherein the filter cage extends along an axis and is configured to be rotatable within the filter unit about the axis and removable from the filter unit;

the filter cage comprising:

at least one filter cage sidewall extending parallel to the axis, the at least one filter cage sidewall comprising a first end and an opposing second end, the filter cage sidewall together with the first and second end defining an interior and exterior of the filter cage, wherein the filter cage sidewall is or comprises one or more than one filter media for filtering microparticles from a feed liquid, the filter media defining a filtration surface on the interior of the filter cage where filtered microparticles accumulate during filtering;

a moveable member in the interior the filter cage comprising a filtration surface cleaning portion which is proximal to the filtration surface;

a user operable portion, at the second end, adapted to be operated by hand on the exterior of the filter cage;

wherein the first end of the filter cage is or comprises an opening for extraction of filtered microparticles from the filter cage when the filter cage is removed from the filter unit and for supply of feed liquid into the filter cage when the filter cage is inside the filter unit;

and wherein the moveable member is connected to the user operable portion so that movement of the user operable portion causes movement of the filtration surface cleaning portion relative to the filter cage to detach filtered microparticles from the filtration surface to pass out of the opening at the first end of the filter cage.

2 . A filter cage according to claim 1 , wherein the user operable portion is configured to be moved by rotating around the axis.

3 . A filter cage according to claim 1 , wherein the moveable member is removable from the interior of the filter cage.

4 . A filter cage according to claim 3 , wherein the movable member comprises a secondary filtration surface cleaning portion which is proximal to the filtration surface and is configured to remove filtered microparticles from the filtration surface when the movable member is removed from the filter cage.

5 . A filter cage according to claim 1 , wherein the moveable member is connected to the user operable portion by being integrally formed, by additional mechanical components or by magnetic connection.

6 . A filter cage according to claim 1 , wherein the moveable member comprises one or more blades which extend along the length of the filter cage sidewall, optionally wherein the one or more blades are linear and extend parallel to the axis.

7 . A filter cage according to claim 6 , wherein the filter cage is configured so that the one more blades rotate with the filter cage when the filter cage is rotating, but rotate relative to the filter cage when rotated by the user operable portion; and optionally, wherein the one or more blades are configured to function as an impellor when the filter cage is rotating.

8 . A filter cage according to claim 7 , wherein the user operable portion is configurable between a first configuration where the user operable portion cannot rotate relative to the filter cage, and a second configuration where the user operable portion can rotate relative to the filter cage.

9 . A filter cage according to claim 8 , wherein one of the user operable portion and the filter cage comprise one or more latches to engage with one or two or more than two engagement members on the other of the user operable portion and the filter cage.

10 . A filter unit according to claim 1 , wherein the first end of the filter cage comprises an opening where an edge of the opening is coincident with the filter cage sidewall.

11 . A filter cage according to claim 1 wherein filtered microparticles can be removed from the filter cage without opening the second end of the filter cage.

12 . A filter unit comprising:

a filter chamber extending along the axis, and comprising opposing first end and second end walls and at least one sidewall extending between the first end and second end walls, wherein both first end and second end walls are coincident with the axis, and wherein the second end wall is or comprises an opening therein and a cap removable from the opening;

a filter cage according to claim 1 , contained within the filter chamber and configured to rotate about the axis, wherein the filter cage is removable from the filter chamber through the opening in the second end wall; and

wherein the filter chamber further comprises an inlet configured to pass feed liquid into the filter chamber to supply feed liquid into the filter cage via the opening at the first end of the filter cage when the filter is in the filter chamber; and an outlet for passage of filtered liquid out of the filter chamber.

13 . A filter unit according to claim 12 wherein the filter unit further comprises:

a connection member comprising a first seal surface and a first connection surface; and

a drive shaft configured to drive rotation of the filter cage;

wherein the first seal surface is configured to cooperate with a second seal surface to provide a rotary seal permitting relative rotation therebetween and the first connection surface is configured to cooperate with the second connection surface to provide a detachable connection therebetween;

wherein the second seal surface is on the filter chamber and the second connection surface is on the filter cage or wherein the second seal surface is on the filter cage and the second connection surface is on the filter chamber.