Dual media system for treating wastewater containing selenium

Patent metadata

Field	Value
Publication number	US-2016264440-A1
Application number	US-201514969796-A
Country	US
Kind code	A1
Filing date	Dec 15, 2015
Priority date	Mar 11, 2015
Publication date	Sep 15, 2016
Grant date	—

Abstract

A bioreactor has a biofilm supporting bed with at least two types of media. An upper media is relatively porous, preferably porous enough to admit particles of a lower media. In use, wastewater flows downwards through the bed. Soluble nitrogen is reduced in the upper media and converted into nitrogen gas. Nitrogen gas bubbles rise through the upper media and escape from the bed. Selenium is reduced in the lower media and converted into elemental selenium. The elemental selenium is released periodically by backwashing the bed, which may cause fluidization or other expansion of the lower media into the upper media.

First claim

We claim:

1 . A reactor for treating selenium-containing water, comprising:
an upstream medium and a downstream medium wherein the upstream medium is more porous than the downstream medium.

2 . The reactor of claim 1 comprising organisms capable of reducing nitrogen attached to the upstream medium and organisms capable of reducing selenium attached to the downstream medium.

3 . The reactor of claim 1 wherein the upstream medium is located above the downstream medium.

4 . The reactor of claim 1 wherein the upstream medium is sufficiently porous so as to admit particles of the downstream medium.

5 . The reactor of claim 1 further comprising a pipe in or downstream of the downstream medium connected to a supply of backwashing fluid.

6 . A process for treating water containing selenium comprising the steps of reducing nitrogen in an upstream medium and reducing selenium in a downstream medium.

7 . The process of claim 6 wherein the upstream medium is located above the downstream medium in a reactor.

8 . The process of claim 6 including a step of backwashing the downstream medium wherein a portion of the downstream medium enters the upstream media bed.

Assignees

• Gen Electric

Inventors

• Fonseca Nelson
• Cumin Jeffrey Ronald
• Citulski Joel Alexander

Classifications

• Y02W10/10

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

• C02F2101/106

  Selenium compounds · CPC title

• C02F2003/001

  using granular carriers or supports for the microorganisms · CPC title

• C02F3/00 Primary

  Biological treatment of water, waste water, or sewage {(C02F1/006 takes precedence)} · CPC title

• C02F3/101 Primary

  Arranged-type packing, e.g. stacks, arrays · CPC title