Lowering viscosity of biosolids

1. Procedure for lowering the viscosity of a biosolids material, including:

providing a mixing vessel, the biosolids material being present in the mixing vessel;

the biosolids material in the mixing vessel has a viscosity of V1 centipoise;

providing an amount-A of urea or urea ammonium nitrate (UAN);

at least gently admixing the amount-A of urea or UAN in with the biosolids material, in the vessel, thereby creating a product-P;

the product-P, thus created, has a viscosity of V2 centipoise;

wherein the amount-A, and the manner of the mixing, are such that the viscosity V2 of the product-P is both:

(a) about forty percent of V1 or lower; and

(b) about 100,000 centipoise or lower.

2. As in claim 1 , wherein:

the biosolids material is substantially non-homogeneous;

the material includes clumps, of substantial size, of a more viscous form in a matrix of a less viscous form;

the viscosity V1 is the viscosity of the biosolids material as measured using a viscometer that employs a rotational measuring procedure.

3. As in claim 1 , wherein:

the biosolids material in the vessel includes sewage sludge;

the sewage sludge has already been dewatered to a dry-solids-content of about six percent or more.

4. As in claim 3 , wherein the sludge:

has been dewatered to a solids content of about ten percent or more;

has been violently sheared, and has thereby been transformed into an homogeneous liquid; and

the liquid has a viscosity V1 of about 30,000 centipoise or lower.

5. As in claim 3 , wherein the sludge is, or includes, residue from a municipal sewage treatment plant, being a plant that treats wastewater predominantly from a human population.

6. As in claim 3 , wherein:

the sludge is already-dewatered sludge that has been violently sheared, to the extent that the viscosity of the sludge placed in the mixing vessel is below 100,000 centiPoise; and

the viscosity V1 is the viscosity of the sludge prior to its being violently sheared.

7. As in claim 3 , wherein the sludge has undergone substantial anaerobic digestion reactions and processes.

8. As in claim 1 , wherein the mass of the amount-A of urea or UAN added to and mixed with the biosolids material to create the product-P of viscosity V2 centipoise, is substantially smaller than the mass of an amount-W of water that, if added to the sludge, would have lowered the viscosity thereof to V2.

9. As in claim 1 , including:

subjecting the mixture in the vessel to violent shearing while the urea or UAN is being added to the biosolids material, or after the urea or UAN has been added;

the shearing being done in such manner as to:

(a) render the product-P highly homogeneous; and

(b) lower the viscosity V2 of the product-P to about twenty percent of V1, or lower.

10. As in claim 1 , including:

measuring, with a viscometer:—

the viscosity V1 of the biosolids material; and

the viscosity V2 of the product-P;

and, responsively to V2 being greater than about forty percent of V1;

or to V2 being greater than about 100,000 centiPoise;

increasing the amount-A of urea or UAN being admixed to the biosolids material.

11. As in claim 1 , including:

collecting the product-P from the vessel;

packaging the product-P for commercial use as an agricultural fertilizer.

12. As in claim 1 , including locating the mixing-vessel in, or close to, a municipal sewage treatment station.

13. As in claim 1 , including:

violently shearing the mixture in the vessel in such manner as to:

(a) create the product-P as a homogeneous liquid; and

(b) lower the viscosity V2 of the product-P to about twenty percent of V1, or lower.

14. As in claim 1 , wherein:

the biosolids material is homogeneous, to the extent that, if viscosity measurements were taken throughout the material, all the measurements would be substantially the same; and

the product-P is homogeneous, to the extent that, if viscosity measurements were taken throughout the product-P, all the measurements would be substantially the same.

15. As in claim 1 , including only gently stirring or mixing the amount-A of urea or UAN in with the biosolids material, in the vessel, without violent shearing.