Method and apparatus for solids processing

1. A closed anaerobic digester for digesting high-solids waste material, the anaerobic digester comprising:

a first section configured to receive the waste material from a source outside of the closed anaerobic digester and to preheat the waste material;

a second section configured to receive the preheated waste material from the first section and to anaerobically digest the preheated waste material, the second section having a first passage and a second passage separated from the first passage by a center wall , wherein the waste material flows in a first direction in the first passage and flows in an opposite direction in the second passage; and

a heating device positioned along and near the center wall configured to induce convection of the waste material flowing through the first passage and the second passage and to heat the waste material with a gas, wherein the heating device includes a conduit having at least one gas outlet positioned to promote upward movement of the heated waste material.

2. The anaerobic digester of claim 1 , further comprising an outer wall, and the outer wall is cooler than the center wall.

3. The anaerobic digester of claim 1 , wherein the heating device is positioned in the first passage and in the second passage.

4. The anaerobic digester of claim 1 , wherein the gas outlet dispenses heated gas to upwardly move the waste material and facilitate a corkscrew-like flow path.

5. An anaerobic digester for digesting high-solids waste material, the anaerobic digester comprising:

a closed container having an inlet and an outlet;

a flow path between the inlet and the outlet within the closed container;

a center wall defining a shape of the flow path, the center wall having a first side and a second side, the flow path flowing in a first direction on the first side of the center wall and flowing in a second direction opposite the first direction on the second side of the center wall; and

a heating device comprising a conduit with at least one gas outlet dispensing heated gas to upwardly move the waste material, the heating device positioned along and near the center wall and in the flow path and configured to induce corkscrew-like flow of the waste material.

6. The anaerobic digester of claim 5 , wherein at least a portion of the flow path is generally U-shaped.

7. The anaerobic digester of claim 5 wherein the closed container comprises an outer wall that is cooler than the center wall.

8. The anaerobic digester of claim 7 wherein the heated waste material falls along the cooler outer wall.

9. The anaerobic digester of claim 5 wherein the waste material is a high-solids waste material having greater than 5 wt % solids content.

10. The anaerobic digester of claim 5 wherein the heating device is positioned along the first side and the second side of the center wall.

11. The anaerobic digester of claim 5 wherein the length of each passage is greater than the respective passage width.

12. An organic waste material processing system for the anaerobic digestion of high-solids waste, the waste material processing system comprising:

a closed container with an outer wall for holding high solids waste material, the closed container including:

a first passage in which the waste material flows in a first direction, the first passage having first and second ends, the first end including an inlet for waste material,

a second passage in which the waste material flows in a direction opposite the first direction, the second passage having first and second ends, the second end including an outlet, the first passage being separated from the second passage by a center wall defining a U-shaped passage between the first passage and the second passage, the second end of the first passage being adjacent the first end of the second passage, and the first end of the first passage being adjacent the second end of the second passage, and

a heating device positioned along and near the center wall in the first passage and in the second passage resulting in the outer wall being cooler than the center wall, the heating device heating the waste material with a gas and to induce the waste material to move in a corkscrew-like fashion through at least one of the first passage and the second passage, wherein the heating device includes a conduit having at least one gas outlet positioned to promote upward movement of the heated waste material.

13. An organic waste material processing system for the anaerobic digestion of high-solids waste, the waste material processing system comprising:

a closed container for holding high solids waste material, the closed container including:

a first passage in which the high-solids waste material flows in a first direction, the first passage having first and second ends, the first end including an inlet for waste material,

a second passage in which the waste material flows in a direction opposite the first direction, the second passage having first and second ends, the second end including an outlet, the first passage being separated from the second passage by a center wall, the second end of the first passage being adjacent the first end of the second passage, and the first end of the first passage being adjacent the second end of the second passage, and

a heating device positioned along and near the center wall in the first passage and in the second passage to heat the waste material with a gas and to induce the waste material to move in a corkscrew-like fashion through at least one of the first passage and the second passage, wherein the heating device includes a conduit having at least one gas outlet positioned to promote upward movement of the heated waste material; and

a mixing chamber adjacent the inlet, the mixing chamber including a means for preheating the waste material before the waste material passes through the inlet to the closed container.

14. The system of claim 13 , further comprising a clarifier adjacent the outlet, the clarifier receiving waste material from the second passage and the clarifier providing a settling tank for separation of solids from liquid.

15. A method for the anaerobic digestion of high solids waste material, the method comprising:

directing high solids waste material along divided first and second passages of a closed container such that the material flows in a first direction in the first passage and a second direction that is substantially opposite the first direction while in the second passage;

expelling a heated gas via a conduit which extends along and near a center wall positioned between the first passage and the second passage to heat the high-solids waste material within the container and to promote upward movement of the heated waste material along the center wall;

inducing the waste material to move in a corkscrew-like fashion through the first passage in one direction and through the second passage in an opposite direction, using the gas.

16. The method of claim 15 wherein the gas is a recycled biogas.