Dewatering of wastewater treatment wastes
First Claim
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1. A process for dewatering wastewater treatment wastes such as skimmings or sludges, comprising:
- supplying wastewater treatment wastes of water and buoyant or precipitated impurities that had been previously coagulated during a primary treatment of the wastewater;
entering said wastewater treatment wastes into a lower portion of a vertical column, said entering step being downwardly through a vertical zone;
spreading said wastes at the lowermost portion of said vertical zone;
passing a dense supply of small gas bubbles from a source lower than said lowermost portion of the vertical zone upwardly through said spread wastes;
upwardly feeding a polymer flocculant at a location lower than said lowermost portion of the vertical zone and above the source of bubbles;
permitting said spread wastes to contact said gas bubbles and floc to thereby form buoyant composites with the previously coagulated impurities within said wastes, confining said composites within said column, said confining step enhancing vertical movement of water and composites while limiting their horizontal movement;
dewatering said wastes by permitting said dense supply of small gas bubbles to continue to rise within the vertical column and thereby downwardly displace all but a residual amount of water from said wastes to form an upper stratum of buoyant composites in wastes that have an impurities content significantly greater than that of said supplied wastes and a lower stratum of substantially clarified water; and
separating said upper stratum and said lower stratum.
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Abstract
Wastewater treatment wastes, such as skimmings or sludges, are processed so as to reduce the water content by approximately two thirds and increase the impurities content thereof. The wastes are passed over a dense supply of very fine bubbles. These fine bubbles assist in floating impurities within the wastes to result in the formation of an upper stratum of gas, residual water and a concentrated impurities content and of a lower stratum that is primarily water, after which the upper and lower strata are separated.
37 Citations
20 Claims
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1. A process for dewatering wastewater treatment wastes such as skimmings or sludges, comprising:
- supplying wastewater treatment wastes of water and buoyant or precipitated impurities that had been previously coagulated during a primary treatment of the wastewater;
entering said wastewater treatment wastes into a lower portion of a vertical column, said entering step being downwardly through a vertical zone;
spreading said wastes at the lowermost portion of said vertical zone;
passing a dense supply of small gas bubbles from a source lower than said lowermost portion of the vertical zone upwardly through said spread wastes;
upwardly feeding a polymer flocculant at a location lower than said lowermost portion of the vertical zone and above the source of bubbles;
permitting said spread wastes to contact said gas bubbles and floc to thereby form buoyant composites with the previously coagulated impurities within said wastes, confining said composites within said column, said confining step enhancing vertical movement of water and composites while limiting their horizontal movement;
dewatering said wastes by permitting said dense supply of small gas bubbles to continue to rise within the vertical column and thereby downwardly displace all but a residual amount of water from said wastes to form an upper stratum of buoyant composites in wastes that have an impurities content significantly greater than that of said supplied wastes and a lower stratum of substantially clarified water; and
separating said upper stratum and said lower stratum. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
- supplying wastewater treatment wastes of water and buoyant or precipitated impurities that had been previously coagulated during a primary treatment of the wastewater;
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14. An apparatus for dewatering primary wastewater treatment wastes such as skimmings or sludges, comprising:
- a vertical chimney;
a vertical inlet means opening into said chimney for introducing primary wastewater treatment wastes into the lower portion of the chimney;
bubble supply means within said chimney and below said vertical inlet means;
an injector located below said vertical inlet means and above said bubble supply means;
a deflecting means communicating with said vertical inlet means for spreading said wastes into extensive contacting relationship with bubbles from said bubble supply means and with polymer flocculant supplied through said injector;
an efflux means that is in communication with a vertical side of said chimney at a location below said bubble supply means, the horizontal distance between said vertical inlet means and said efflux means being less than the height of the vertical chimney; and
said efflux means has a maximum height at least as high as the height of the wastes in the chimney. - View Dependent Claims (15, 16, 17, 18, 19, 20)
- a vertical chimney;
Specification