Treatment of waste products with anaerobic digestion

Patent metadata

Field	Value
Publication number	US-9809481-B2
Application number	US-201615005469-A
Country	US
Kind code	B2
Filing date	Jan 25, 2016
Priority date	Jan 27, 2015
Publication date	Nov 7, 2017
Grant date	Nov 7, 2017

Abstract

A waste stream is treated by anaerobic digestion. A process is described involves a step of separating solids from digestate, and returning separated solids to a digester. Optionally, there may be a step of solids separation in which larger solids are removed from the digester. A process and apparatus are described for treating waste sludge from a wastewater treatment plant in an anaerobic digester. Feed sludge is thickened or solids are separated from digestate and returned to the digester. Additional co-digestion waste may be added to the digester. The process and apparatus may be used in a retrofit of an existing wastewater treatment plant.

First claim

I claim:

1. A process for treating WWTP sludge comprising the steps of,
feeding the WWTP sludge at 12-20% TS to an anaerobic digester;
operating the anaerobic digester at 6-12% TS without recuperative thickening; and,
dewatering digestate in two stages.

2. The process of claim 1 further comprising adding nutrients to the digester in an amount effective to alleviate ammonia toxicity.

3. The process of claim 1 further comprising mixing the digester with a hydraulic or electric motor mixer.

4. The process of claim 1 comprising feeding the WWTP sludge at 15-20% TS to the anaerobic digester.

5. The process of claim 1 wherein the digestate is dewatered without a polymeric dewatering aid in a first stage and dewatered with a polymeric dewatering aid in a second stage.

6. The process of claim 1 wherein a portion of the WWTP sludge is dewatered before being fed to the anaerobic digester.

7. A process for treating WWTP sludge comprising the steps of, feeding the WWTP sludge at 1-5% TS to an anaerobic digester;
operating the anaerobic digester at 4-6% TS; and,
providing recuperative thickening for the digester by way of a side stream thickener; and,
adding a polymeric thickening aid in the side stream,
wherein the polymeric thickening aid is added at 3 kg/MT-TSS or less.

8. The process of claim 7 wherein waste digestate is dewatered separately from the side stream.

9. The process of claim 8 wherein a polymeric thickening aid is added at 7 kg/MT-TSS or less for dewatering.

10. The process of any claim 7 further comprising mixing the digester with a hydraulic or electric motor mixer.

Assignees

• Anaergia Inc

Inventors

• Josse Juan Carlos

Classifications

• C02F2103/32

  from the food or foodstuff industry, e.g. brewery waste waters · CPC title

• C02F2305/06

  Nutrients for stimulating the growth of microorganisms · CPC title

• C02F11/126

  using drum filters · CPC title

• C02F2209/10

  Solids, e.g. total solids [TS], total suspended solids [TSS] or volatile solids [VS] · CPC title

• C02F11/125

  using screw filters · CPC title