Solid waste treatment with conversion to gas and anaerobic digestion

Patent metadata

Field	Value
Publication number	US-9868964-B2
Application number	US-201615015479-A
Country	US
Kind code	B2
Filing date	Feb 4, 2016
Priority date	Feb 6, 2015
Publication date	Jan 16, 2018
Grant date	Jan 16, 2018

Abstract

Waste solids are treated by pyrolysis at a temperature over 700 degrees C. to produce char and a gas. The gas is treated in an anaerobic digester. In one system, gas and digestate are brought into contact in a diffusion cone. In another option, headspace gas above the digestate is re-circulated through the digestate, for example by way of an eductor downstream of the diffusion cone.

First claim

We claim:

1. A process comprising steps of,
a) producing a gas containing hydrogen and carbon monoxide from pyrolysis of a feedstock at a temperature of over 750 degrees C.; and,
b) adding the gas to an anaerobic digester,
wherein the feedstock comprises plastic.

2. The process of claim 1 wherein the feedstock comprises a mixture of biogenic and non-biogenic material.

3. The process of claim 1 wherein the anaerobic digester is coupled with or part of a municipal wastewater treatment plant.

4. The process of claim 1 comprising producing a gas containing hydrogen and carbon monoxide from pyrolysis of a feedstock at a temperature of 800 degrees C. or more.

5. An apparatus for transferring syngas to digestate comprising a diffusion cone in a sidestream loop wherein the diffusion cone defines an outer surface of part of the sidestream loop with a downwardly increasing cross sectional area.

6. The apparatus of claim 5 having an eductor in the sidestream loop downstream of the diffusion cone and connected to a headspace of the digester.

7. A process for treating wastewater comprising,
a) treating the wastewater to generate a sludge;
b) feeding the sludge to an anaerobic digester to produce biogas and digestate;
c) dewatering the digestate to produce a cake;
d) thermally drying the cake to produce a dried cake;
e) pyrolysing the dried cake at a temperature of over 700 degrees C. or more to produce char and syngas;
f) feeding the syngas to the anaerobic digester;
g) monitoring one or more indicators of carbon monoxide inhibition in the anaerobic digester.

8. The process of claim 7 comprising pyrolysing the dried cake at a temperature of over 800 degrees C. or more.

Assignees

• Anaergia Inc

Inventors

• Josse Juan Carlos
• Scherson Yaniv D

Classifications

• C12P5/023 Primary

  Methane · CPC title

• C02F11/10

  by pyrolysis · CPC title

• Y02E50/343

  Cross-Sectional Technologies · mapped topic

• C02F2303/06

  Sludge reduction, e.g. by lysis · CPC title

• C02F9/00

  Multistage treatment of water, waste water or sewage · CPC title