An apparatus for purifying unclarified water of the type including a cylindrically shaped tank having an upwardly directed outer wall and a generally flat bottom,
- an inlet pipe extending vertically through the center portion of said tank,
- a cylindrically shaped compartment positioned about said inlet pipe in the center portion of said tank and having an upwardly directed outer wall,
- a carriage supported between the upper portion of said tank wall and the upper portion of said compartment wall,
- means for circular movement of said carriage around the vertical axis of the tank supported by said carriage, and means on said carriage supporting a fluid distributor in fluid communication with said inlet pipe to discharge inlet water into said tank, and a spiral scoop sludge collector,
- the improvement comprising means defining a flocculation chamber having a closed front end, an open back end, and a closed bottom carried by said carriage,
- said fluid distributor positioned ahead of the closed end of said flocculation chamber,
- an upwardly directed circular wall defining a sludge storage space within said compartment around said inlet pipe to receive sludge collected by said scoop,
- sludge discharge means for said sludge storage space,
- said upwardly directed circular wall defining with the wall of said compartment a clarified water storage space positioned outwardly of said sludge storage space,
- clarified water discharge means for said clarified water storage space,
- filter means extending substantially over the bottom of said tank outwardly of said cylindrically shaped compartment,
- means radially dividing said filter means into horizontally positioned sections,
- horizontally extending filter partitions extending across said horizontally positioned sections defining filter receiving space on the top thereof,
- said horizontally extending filter partitions defining clarified water receiving spaces positioned thereunder,
- clarified water inlet means leading from said clarified water receiving space to said clarified water storage space,
- filter back washing means for at least one of said filter sections carried by the carriage at the leading end thereof and operable while the remainder of said filter sections are filtering water into said clarified water storage space,
- dissolved air in water injection means carried by the carriage at the lower back end of the flocculation chamber above the floor thereof and providing air bubble action engaging flocs in the water and producing a generally upward current flow of water and flocs in said tank in the vicinity of said bubble action,
- said filter means permitting the outward flow of clarified water from the lower portion of said tank thereby producing a downward current flow of water and flocs in said tank at a lesser rate than the rate of upward current flow produced by said air bubble and said water in which said air was dissolved in the vicinity thereof so that the majority of flocs in the water are floated to be removed by said spiral scoop and the remainder of the flocs are deposited on said filter means to be subsequently removed by the action of said backwashing means.