Method for treating wastewater sludge
AssigneeN-Viro Energy Systems Ltd.
InventorsJohn P. Nicholson, Jeffrey C. Burnham
Life of this patent
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Abstract
A method of decontaminating wastewater sludge to a level that meets or exceeds USEPA Process to Further Reduce Pathogens standards, wherein lime or kiln dust and/or other alkaline materials are mixed with wastewater sludge in sufficient quantity to raise the pH of the mixture to 12 and above for a predetermined time and drying the resulting mixture.
Claims8
A method of treating wastewater sludge to provide a fertilizer for agricultural lands which can be applied directly to the lands which consists essentially of the following steps:
- mixing said sludge with at least one alkaline material;
- wherein the amount of added material mixed with said sludge being sufficient to raise the pH of said mixture to at least 12 and to hold the pH of greater than 12 for at least 7 days,
- and drying said mixture for at least 30 days and until a minimum solids concentration of 65% solids is reached,
- the amount of added material being also sufficient to maintain the pH above 12 until the sludge solids achieve at least 60% solids by weight,
- the amount of added material mixed with said sludge and the length of time of drying being sufficient to reduce significantly offensive odor of the sludge to a level that is tolerable;
- to reduce animal viruses therein to less than one plaque forming unit per 100 ml of said sludge;
- to reduce pathogenic bacteria therein to less than three colony forming units per 100 ml of said sludge;
- to reduce parasites therein to less than one viable egg per 100 ml of said sludge;
- to reduce vector attraction to said sludge;
- and to prevent significant regrowth of the pathogenic microorganisms.
A method of treating wastewater sludge to provide a fertilizer for agricultural lands which can be applied directly to the lands which consists essentially of the following steps:
- mixing said sludge with at least one alkaline material;
- wherein the amount of added material mixed with said sludge being sufficient to raise the pH of said mixture to at least 12 for at least 72 hours,
- concurrently with the high pH heating the mixture to at least 50.degree. C., but not at a temperature sufficient to cause sterilization, the amount of heat being sufficient that the sludge stored in a static condition will be maintained at a temperature of at least 50.degree. C. for at least 12 hours,
- the amount of added material mixed with said sludge and the length of time of drying being sufficient to reduce significantly offensive odor of the sludge to a level that is tolerable;
- to reduce animal viruses therein to less than one plaque forming unit per 100 ml of said sludge;
- to reduce pathogenic bacteria therein to less than three colony forming units per 100 ml of said sludge;
- to reduce parasites therein to less than one viable egg per 100 ml of said sludge;
- to reduce vector attraction to said sludge;
- and to prevent significant regrowth of the pathogenic microorganisms.
Dependencies are inferred from the claim text.