Patent ID: 8366931

Claim:
A filtering unit comprising: membranes; positioning rings alternately arranged with the membranes, wherein each of the positioning rings includes: an annular body; arched cutouts defined in an internal edge of the annular body; first engaging members formed on the annular body, wherein each of the first engaging members is located near an end of a corresponding one of the arched cutouts; second engaging members formed on the annular body, wherein each of the second engaging members is located near another end of a corresponding one of the arched cutouts, wherein the second engaging members can be engaged with the first engaging members of another positioning ring extending through the arched cutouts; and at least one slot defined in the annular body; and seals, each including: two sealing portions extending on two opposite faces of the annular body; and at least one connecting portion extending to one of the sealing portions from the other sealing portion through the slot.