Methods and systems for removing nitrates in zero liquid discharge applications

Patent metadata

Field	Value
Publication number	US-2020299166-A1
Application number	US-201816766892-A
Country	US
Kind code	A1
Filing date	Nov 27, 2018
Priority date	Nov 27, 2017
Publication date	Sep 24, 2020
Grant date	—

Abstract

Disclosed herein are a method for treating a water stream in a zero liquid discharge (ZLD) system and a ZLD system. The method includes contacting the water stream with a metal agent that reduces a nitrate contained therein to a nitrite, and introducing an amide into the water stream that reduces the nitrite to nitrogen to provide a treated water stream having a reduced nitrate concentration. The ZLD system includes a mix tank, an amide tank including an amide, and a crystallizer. The mix tank includes an inlet for receiving a water stream within the mix tank, and a container including a metal agent. The container is designed to allow the water stream to contact the metal agent. The amide tank is designed to direct the amide into the water stream, and the crystallizer is designed to receive the water stream from the mix tank.

First claim

What is claimed is:

1 . A method for treating a water stream a zero liquid discharge system, comprising:
contacting the water stream with a metal agent that reduces a nitrate contained therein to a nitrite; and introducing an amide into the water stream that reduces the nitrite to nitrogen, wherein the contacting and introducing steps are effective to provide a treated water stream having a reduced nitrate concentration.

2 . The method according to claim 1 , wherein the zero liquid discharge system comprises a brine concentrator, a crystallizer, and dewatering unit.

3 . The method according to claim 1 , further comprising subjecting the treated water stream to a crystallization treatment.

4 . The method according to claim 1 , wherein the water stream is a filtrate obtained by dewatering a slurry.

5 . The method according to claim 1 , wherein the metal agent is at least one selected from the group consisting of zinc, iron, copper, cadmium, chromium, lead, tin, aluminum, nickel, manganese, magnesium, and alloys and mixtures thereof.

6 . The method according to claim 1 , wherein the amide is at least one selected from the group consisting of sulfamic acid, urea, ammonia, formamide, acetamide, sulfamide, carboxamide, phosphoramide, a secondary amide derived from a primary amine (R′NH 2 ), and a tertiary amide derived from a secondary amine (R′R″NH).

7 . The method according to claim 1 , wherein the metal agent is in the form of a powder, rods, shots, fines, pebbles, impregnated membrane, resin media, or liquid.

8 . The method according to claim 1 , wherein the amide is introduced into the water stream in the form of a liquid.

9 . The method according to claim 1 , wherein the amide is introduced into the water stream before the water stream is contacted with the metal agent.

10 . A zero liquid discharge (ZLD) system comprising:
a mix tank comprising
an inlet for receiving a water stream within the mix tank; and
a container comprising a metal agent that is configured to allow the water stream to contact the metal agent;
an amide tank comprising an amide that configured to direct the amide into the water stream; and a crystallizer configured to receive the water stream from the mix tank.

11 . The ZLD system according to claim 10 , wherein the mix tank further comprises a mixing unit configured to mix the water stream in the mixing tank.

12 . The ZLD system according to claim 10 , wherein the crystallizer is configured to crystallize the water stream.

13 . The ZLD system according to 12 , further comprising a dewatering unit configured to dewater the crystallized water stream to separate solid material from the water stream.

14 . The ZLD system according to claim 13 , wherein the mix tank is configured to receive the water stream from the dewatering unit.

15 . The ZLD system according to claim 13 , wherein the amide tank is configured to direct the amide into the water stream in a line between the dewatering unit and the mix tank.

Assignees

• Chemtreat Inc

Inventors

• Boudreaux Kevin
• Mcilwaine Douglas
• Kalakodimi Rajendra Prasad

Classifications

• B01D53/565

  by treating the gases with solids · CPC title

• B01D9/0059

  General arrangements of crystallisation plant, e.g. flow sheets · CPC title

• C02F1/70 Primary

  by reduction {(C02F1/4676 takes precedence)} · CPC title

• C02F9/00 Primary

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

• C02F11/122

  using filter presses (C02F11/123 takes precedence) · CPC title