Patent ID: 7901576

Claim:
A water treatment vessel comprising: a thermoplastic liner having an inner volume; a reinforcing layer covering the thermoplastic liner, the reinforcing layer comprising a plurality of glass filaments wrapped helically and circumferentially around the thermoplastic liner; and a first distributor plate comprising a first thermoplastic polymeric disk having a top side, a bottom side, a central opening and a perimeter edge that is joined to an inner side of the thermoplastic liner to divide the inner volume of the thermoplastic liner into at least a first compartment and a second compartment; wherein a plurality of slits are formed in the first disk to define fluid flow passages through the first disk between the central opening and the perimeter edge, wherein the fluid flow passages through the first disk are narrower at the top side of the first disk than at the bottom side of the first disk, wherein the fluid flow passages through the first disk are each bounded by a first longitudinal sidewall that is substantially planar and a second longitudinal sidewall that includes a concave portion that faces the first longitudinal sidewall, and wherein the fluid flow passages through the first disk are adapted to swirl liquid flowing through the first disk from the bottom side to the top side around the central opening.