Patent ID: 8157988

Claim:
A sludge recirculation system to be added to a sedimentation zone of a water treatment facility using at least one purification method selected from the group consisting of flocculation, sedimentation, coagulation and ballast flocculation, said sludge recirculation system for repeated cycling of sludge in a progressively water purging fashion, said system comprising: a downstream sludge recovering vessel, including a sludge recovering cavity located at a bottom portion of said vessel, said cavity defining a certain volume of a sedimentation zone wherein said sludge may accumulate therein under the influence of gravity; a recirculation apparatus, comprising: i. liquid and solid separation means that allows the purification of a liquid solution by separating said sludge including low density solids from high density solids; ii. recirculation means, comprising: 1. a recirculation line connected at an intake end thereof to said sludge recovering cavity and connected to said liquid and solid separation means at an outlet end thereof; 2. a reinsertion line operatively connected at an intake end thereof to said liquid and solid separation means and to said sludge recovering vessel at an outlet end thereof, said reinsertion line allowing said sludge including said low density solids to be reinserted into said vessel; and 3. an elimination line connected at an intake end thereof to said reinsertion line and rejecting said sludge including said low density solids outside of said water treatment facility at a downstream outlet end thereof; iii. means active during said repeated cycling of said sludge through the sludge recirculation system for progressively eliminating said sludge including said low density solids from said sludge recirculation system through said elimination line; and iv. means to drive said sludge into said recirculation apparatus during said repeated cycling.