Method and apparatus for thickening

Claim 1

THE METHOD OF THICKENING LIGHT SLUDGES SUCH AS A SEWAGE PLANT SLUDGE WHICH METHOD COMPRISES FIRST DILUTING AND THOROUGHLY MIXING THE SLUDGE WITH RELATIVELY CLEAR EWATER HAVING FINELY DIVIDED AIR BUBBLES OF UP TO ABOUT 100 MICRONS IN DIAMETER ENTRAINED IN SAID WATER AND IN THE RATIO OF AT LEAST ONE PART OF CLEAR WATER TO ONE PART OF SLUDGE SO THAT THE SLUDGE PARTICLES ARE FULLY SEPARATED TO ALLOW THE AIR BUBBLES TO SURROUND THE PARTICLES AND ADHERE THERETO WITHOUT AGGLOMERATING, INTRODUCING SAID DILUTION INTO THE LOWER PORTION OF A TANK TO FLOW BENEATH A QUIESCENT ZONE OF TWO FEET OR MORE IN DEPTH COMPRISING THE UPPER PART OF THE TANK AND AT A RATE THROUGH SAID LOWER PORTION ALLOWING THE AIR-SUPPORTED PARTICLES AND EXCESS BUBBLES TO RISE UNHINDERED BY REASON OF SAID DILUTION INTO THE QUIESCENT ZONE AND TO DISTRIBUTE THEMSELVES OVER THE LOWER AREA THEREOF, AND TO THEREBY DEVELOP A BUOYANT SCUM BLANKET HAVING A UNIFROMLY INCREASING CONCENTRATION GRADIENT APPROACHING THE UPPER LAYER THEREOF AND HAVING A MAXIMUM DEPTH OF ONE FOOT BELOW THE WATER LEVEL OF THE TANK, AND MAINTAINING SAID CONDITIONS TO DEVELOP AND THEREAFTER PROVIDE A CONTINUOUSLY REMOVABLE SCUM LAYER ABOVE SAID WATER LEVEL HAVING A SOLIDS CONCENTRATION IN THE ORDER OF FOUR PERCENT AND OVER AND AT A RATE FOR SUCH REMOVAL OF TEN OR MORE POUNDS OF DRY SOLIDS PER SQUARE FOOT PER DAY, AND REGULARLY REMOVING SAID REMOVABLE SCUM LAYER SO THAT SAID CONCENTRATION GRADIENT IS CONTINUOUSLY MAINTAINED.

Claim 2

THE METHOD OF THICKENING LIGHT SLUDGES SUCH AS A SEWAGE PLANT SLUDGE WHICH METHOD COMPRISES FIRST DILUTING AND THOROUGHLY MIXING THE SLUDGE WITH RELATIVELY CLEAR EWATER HAVING FINELY DIVIDED AIR BUBBLES OF UP TO ABOUT 100 MICRONS IN DIAMETER ENTRAINED IN SAID WATER AND IN THE RATIO OF AT LEAST ONE PART OF CLEAR WATER TO ONE PART OF SLUDGE SO THAT THE SLUDGE PARTICLES ARE FULLY SEPARATED TO ALLOW THE AIR BUBBLES TO SURROUND THE PARTICLES AND ADHERE THERETO WITHOUT AGGLOMERATING, INTRODUCING SAID DILUTION INTO THE LOWER PORTION OF A TANK TO FLOW BENEATH A QUIESCENT ZONE OF TWO FEET OR MORE IN DEPTH COMPRISING THE UPPER PART OF THE TANK AND AT A RATE THROUGH SAID LOWER PORTION ALLOWING THE AIR-SUPPORTED PARTICLES AND EXCESS BUBBLES TO RISE UNHINDERED BY REASON OF SAID DILUTION INTO THE QUIESCENT ZONE AND TO DISTRIBUTE THEMSELVES OVER THE LOWER AREA THEREOF, AND TO THEREBY DEVELOP A BUOYANT SCUM BLANKET HAVING A UNIFROMLY INCREASING CONCENTRATION GRADIENT APPROACHING THE UPPER LAYER THEREOF AND HAVING A MAXIMUM DEPTH OF ONE FOOT BELOW THE WATER LEVEL OF THE TANK, AND MAINTAINING SAID CONDITIONS TO DEVELOP AND THEREAFTER PROVIDE A CONTINUOUSLY REMOVABLE SCUM LAYER ABOVE SAID WATER LEVEL HAVING A SOLIDS CONCENTRATION IN THE ORDER OF FOUR PERCENT AND OVER AND AT A RATE FOR SUCH REMOVAL OF TEN OR MORE POUNDS OF DRY SOLIDS PER SQUARE FOOT PER DAY, AND REGULARLY REMOVING SAID REMOVABLE SCUM LAYER SO THAT SAID CONCENTRATION GRADIENT IS CONTINUOUSLY MAINTAINED.