Disposal method and use of sewage sludge
AssigneeIU Conversion Systems, Inc.
InventorsWilliam C. Webster, Robert G. Hilton, Ronald F. Cotts
Life of this patent
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Abstract
Digested sewage sludge resulting from sewage plant treatment of municipal sewage is disposed of and used in an ecologically acceptable manner by the incorporation of such sludge in hardenable compositions further including, for example, lime, fly ash and, in some cases, alkaline earth metal sulfates and/or soil or other inert or complimentary additives. These hardenable compositions may be emplaced in an area open to the atmosphere and permitted to cure over a period of time to act as land fill or as road base materials.
Claims32
A water-solids mixture hardenable under atmospheric conditions the dry solids of which comprise (based on weight % of dry solids):
- 1-15% lime
- 1-50% digested sewage sludge solids
- 20-90% fly ash, and the water of which provides a moisture content (based also on weight % dry solids) of 5- 50%.
Method of treating a sludge from a municipal sewage plant comprising admixing said sludge with lime and fly ash such that the final composition of said admixture has a moisture content of 5- 50% and the dry solids therein comprise:
- 1-15% lime
- 1-50% digested sewage sludge solids
- 20-90% fly ash, and
- permitting said admixture to harden under atmospheric conditions.
Method of making a load bearing material from a municipal sewage plant sludge, said method comprising admixing said sludge with lime and fly ash such that the final composition has a moisture content of 5-50%, and further comprises 1-15% lime, 1-50% digested sewage sludge solids, and 20-90% fly ash (all percentages based on weight % of solids) and permitting said admixture to harden under atmospheric conditions.
A water-solid mixture hardenable under atmospheric conditions, the dry solids of which comprise (based on weight % of dry solids):
- 1-15% lime or a molar equivalent amount of hydratable alkaline earth oxide or alkaline earth metal hydroxide in a lime substitute selected from the group consisting of BOF dust, lime kiln dust or cement kiln dust,
- 1-50% digested sewage sludge solids,
- 20-90% fly ash, or an equivalent amount of a fly ash substitute selected from the group consisting of siliceous incineration residue, "alum" water treatment plant waste, or "red mud" by-product of a bauxite reduction process, and
- waer sufficient to provide a moisture content (based on weight % of dry solids) of 5- 50%, the combination of said materials being cementitiously hardenable under atmospheric conditions.
A water-solids mixture hardenable under atmospheric conditions, the dry solids of which comprise (based on weight % of dry solids):
- 1-15% lime or a lime substitute providing a molar equivalent amount of hydratable alkaline earth oxide or alkaline earth metal hydroxide, said lime substitute comprising BOF dust, cement kiln dust, lime kiln dust, alkaline earth metal oxide or alkaline earth metal hydroxide,
- 1-15% digested sewage sludge solids,
- 1-10% calcium sulfate anhydrite or other alkaline earth metal sulfates in an amount equal to 1-10% calcium sulfate anhydrite on a molar basis,
- 20-90% fly ash or an equivalent amount of another waste material having pozzolanic activity selected from the group consisting of siliceous incineration residue, "alum" water treatment plant waste, or "red mud" by-product of a bauxite reduction process, and
- water sufficient to provide a moisture content (based on weight % of dry solids) of 5-50%, the combination of said materials being cementitiously hardenable under atmospheric conditions.
Method of treating a sludge from a municipal sewage treatment plant comprising admixing said sludge with lime or a lime substitute material selected from the group consisting of BOF dust, lime kiln dust, cement kiln dust, hydratable alkaline earth metal oxide and alkaline earth metal hydroxide, and a pozzolanic reactant selected from the group consisting of fly ash, siliceous incineration residue, "alum" water treatment plant waste, and "red mud" by-product of a bauxite reduction process such that the final composition of said admixture has a moisture content of 5-50% (based on weight % of solids) and a dry solids content (based on weight % solids) comprising:
- 1-15% lime or a lime substitute providing a molar equivalent amount of alkaline earth metal hydroxide, or hydratable alkaline earth oxide,
- 1-50% digested sewage sludge solids,
- 20-90% fly ash or "fly ash equivalent amounts" of said pozzolanic reactant and permitting said admixture to harden under atmospheric conditions.
Method, as recited in cliam 22, wherein said mixture further includes alkaline earth metal sulfate in an amount which is the molar equivalent of 1- 10% calcium sulfate anhydrite.
Dependencies are inferred from the claim text.