# US 9,039,904 B2 · Method for treating wastewaters

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- Number: US 9,039,904 B2
- Document ID: US9039904B2
- Status: Granted
- Kind: B2
- Application number: 13/147,627
- Filed: 2010-01-27
- Published: 2011-12-22
- Granted: 2015-05-26
- Earliest claimed: 2009-02-06
- Assignees: Bayer MaterialScience AG
- Applicants: Andreas Karl Rausch; Christoph Blöcher
- Inventors: Andreas Karl Rausch; Christoph Blöcher
- Web page: https://patentgrep.com/patent/US9039904B2

## CPC

- C02F 1/727: {using pure oxygen or oxygen rich gas}
- C02F 1/286: {using natural organic sorbents or derivatives thereof}
- C02F 1/70: by reduction {(C02F1/4676 takes precedence)}
- C02F 9/00: Multistage treatment of water, waste water or sewage
- C02F 11/08: Wet air oxidation
- C02F 1/283: {using coal, charred products, or inorganic mixtures containing them}
- C02F 1/66: by neutralisation; pH adjustment (for degassing C02F1/20; using ion-exchange C02F1/42; for flocculation or precipitation of suspended impurities C02F1/52; for removing dissolved compounds C02F1/58)
- C02F 2101/003: {Explosive compounds, e.g. TNT}
- C02F 2101/38: containing nitrogen
- C02F: TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE (separation in general B01D; special arrangements on waterborne vessels of installations for treating water, waste water or sewage, e.g. for producing fresh water, B63J; adding materials to water to prevent corrosion C23F; treating radioactively-contaminated liquids G21F9/04; regeneration of reactants for recirculation into processes, see the relevant places for the processes)

## Abstract

The invention relates to a method for treating wastewater containing nitroaromatics and nitrohydroxyaromatics, as for example arises in the production of nitroaromatics or in the production of nitrohydroxyaromatics, by a two-stage method consisting of pre-reduction and wet oxidation.

## Claims

### Claim 1

A method for treating alkaline wastewater containing nitroarornatics and/or nitrohydroxyaromatics, comprising, in a first stage combining the alkaline wastewater with an organic reducing agent which is non-salt-forming in the wastewater, said organic reducing agent being selected from the group consisting of lignite and hard coal and treating the alkaline wastewater under reducing conditions, wherein the alkaline wastewater is heated to a temperature range of from 80 to 200° C. and maintained in said temperature range for a residence time of from 5 minutes to 5 hours to produce a reduced wastewater and, in a second stage, acidifying and oxidising the reduced wastewater obtained from the first stage with an oxidising agent.

### Claim 2 (depends on 1)

A method according to claim 1, characterised in that oxygen is used as the oxidising agent.

### Claim 3 (depends on 1)

A method according to claim 1, characterised in that the second stage is performed in a reactor, into which acid is directly introduced and in which the oxidation is performed

### Claim 4 (depends on 1)

A method according to claim 1, characterised in that the wastewater containing nitroaromatics and/or nitrohydroxyaromatics originates from the production of nitrobenzene or dinitrotoluene

### Claim 5 (depends on 1)

The method of claim 1, wherein the alkaline wastewater is heated to a temperature range of from 120 to 200° C.

### Claim 6 (depends on 1)

The method of claim 1, wherein the alkaline wastewater is heated to a temperature range of from 180 to 200° C.