DD97184B1 - METHOD FOR THE CONTINUOUS CLEANING OF OXIDIZABLE SUBSTANCES - Google Patents

Description

Field of application of the invention

The invention relates to a process for the purification of wastewater contaminated with oxidizable substances, in particular from polyurethane and / or herbicidal production. These waste water are u.a. with glycols, highly functional alcohols, higher molecular weight polyether alcohols, phenols such as chlorinated phenols, phenoxycarboxylic acids and the like. Like. Loaded, which have toxic character and are not biodegradable or difficult to biodegrade.

Characteristic of the known technical solutions

Wastewater that is contaminated with organic, non-biologically and / or poorly degradable substances are by adsorptive treatment by means of surface-active substances, eg. As activated carbons, cleaned or eliminated by combustion at temperatures above 1100 ° C.

Many organic substances are well adsorbed by activated carbons. The regeneration of coal is often problematic or not possible. This makes this process very expensive.

Combustion of sewage contaminated with chemical substances above 1100 ° C is very expensive for energetic reasons.

The known biological purification processes have the disadvantage that they come to a standstill through biologically toxic substances or allow non-degradable substances to pass through. In addition, one finds in the literature information that z. B. biosurfactants and some spezieile wastewater, such as sulfite liquor, lignin solutions, formic acid, methanol-containing and formaldehyde-containing solutions are wet-oxidatively cleaned with residence times of about 20 to 30 minutes at temperatures of 250 to 372 ° C and a pressure of 15 to 20MPa.

In this case, especially z. B. in the sludge formation, at temperatures above 250 ° C, 70-80% of the substances oxidized. The disadvantages of the previously known wet air oxidation plants include u.a. in the high residence times (reduced space-time yield, high pressures (increasing plant and energy costs and the relatively low oxidation rates.) The known wet air oxidation processes are used to purify waste liquors from pulp mills or wastewaters loaded with low molecular weight substances such as acetic acid, methyl alcohol, etc. Owing to the difficulty of catalysis in the aqueous phase, oxidic noble contacts or all-metal catalysts are used (GBPS 694458) .These full contacts have a relatively small active surface and are only suitable for the degradation of substances which are biodegradable anyway There are also no wet-air oxidation processes for substances with high molecular weight, toxic and non-biodegradable or difficultly degradable substances in an aqueous medium, and attempts to purify such effluents by catalytic means have not led to a positive result on a large scale.

Object of the invention

The aim of the invention is to develop a process for the purification of toxic, non-biodegradable or difficult to decompose effluents from the polyurethane and / or herbicidal production, which works up with low residence time toxic or harmful components so that then a biological purification is possible.

Explanation of the essence of the invention

The invention has for its object to develop a process for the purification of toxic or harmful components containing wastewater, which achieves a good cleaning effect by means of catalyst at technically acceptable temperatures and pressures in the aqueous phase.

According to the invention the object is achieved in that the wastewater to be purified from the polyurethane and / or herbicides mixed with an oxygen-releasing and / or oxygen-containing medium brought to reaction temperatures between 100 to 300 ⁰ C and pressures of 3 to 10 MPa, one filled with catalyst Flowed through reactor from bottom to top. According to the invention, supported catalysts are used to increase the phase contact surface and thus to reduce the residence time, with known carrier materials having up to 50% copper oxide or mixtures of about 4% copper oxide _; 7% chromium, 5% zinc oxide or 6% copper, 5% Ch; om, 3% manganese oxide or 4% copper, 8% chromium oxide or precious metals, such as platinum and / or palladium with a concentration of about 0.1% to 1% as active

Components are used. .__ _ .. ._.

Biologically 'heavy or not degradable and / or toxic ingredients of the effluents are so inoxidized with low residence times that they are amenable to further biological wastewater treatment.

After the reaction, the reaction products are cooled and separated in the gas and liquid phases, the liquid being fed to a tilted biological purification stage.

In the case of effluents whose constituents have an acid reaction and / or are expected to occur after treatment, the stoichiometric amount of basic substances is previously added. The residence time due to the large surface area of the supported catalyst can be reduced to about 8 to 10 min., Compared to the literature data (20 to 30 min.), And from 90 to almost 100% degradation of the oxidizable substances.

The waste heat of the heating medium, which is due to the process incurred in the heating of the wastewater, for example, is available for a catalytic exhaust gas purification.

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/ orteilhaft here is that a good utilization of the heat energy is given, through which the inventive method hole is made more economical.

= in cleaning the wastewater from the polyurethane and / or herbicide by a biological process without prior inventive thermal-catalytic treatment leads to succumbing to biology, or leaving such pollutants without degradation, the biological treatment stage and get into the receiving water. By the method according to the invention is achieved in any case that the wastewater from the polyurethane and herbicide production are derived vorflutgerecht. The inventive method is compared to known methods for the destruction of such pollutants substantially cost and energy saving.

Exemplary embodiments

As a measure of wastewater pollution and / or pollution reduction, chemical oxygen consumption (CSV) and / or chemical analysis are chosen.

example 1

A 0.1% phenol solution, derived from the production of pesticides containing phenoxycarboxylic acids, is treated with a stoichiometric calculation corresponding 5-fold excess of air and at a load of 6m ³ wastewater per m ³ contact and hour and reactor temperatures of 275 ⁰ C and a pressure of 10 MPa over a catalyst consisting of a mixture of 4% copper, 7% chromium, 5% zinc oxide passed on y-alumina Oxidative degradation of the phenol was> 99%.

Example 2

A 0.1% aniline solution is added with a 5-fold excess of air and at a load of 6 m ³ wastewater per m ³ contact and hour and reactor temperatures of 275 ° C and a pressure of 8.5 MPa over a catalyst consisting of a mixture of 4% copper, 7% chromium, 5% zinc oxide passed on y-alumina. In the reaction mixture could no longer be detected after passing through the reactor aniline. The CSV degradation was 84%.

Example 3

A 0, S% glycol solution, consisting of different partially more functional alcohols and higher molecular weight polyether alcohols, originating from the production of polyether alcohols for polyurethane production, is treated with an excess of air and at a load of 7 m ³ wastewater per m ³ contact and Hour and reactor temperatures of 300 ° C and a pressure of 10 MPs over a catalyst consisting of 50% copper oxide passed on magnesium silicate. The CSV degradation was 95%.

Example 4

A 0.1% nitrobenzene solution is treated with an excess of air and at a load of 6m ³ wastewater per m ³ contact and hour and reactor temperatures of 275 ⁰ C and a pressure of 7.5 MPa over a catalyst consisting of 6% copper -, 5% chromium, 3% manganese passed on y-alumina. The oxidation of the nitrobenzene exceeded 90%, as well as the CSV degradation.

Example 5

An offset with 0.5% dimethylformamide aqueous solution is mixed with a 6-fold excess of air and a

Loading of 5 m ^{3 of} wastewater per m ^{3 of} contact and hour and reaction temperatures of 275 ° C and a pressure of 10 MPa over a catalyst consisting of 4% copper, 8% chromium oxide passed on y-alumina. The reduction of the CSV value was

The residence times in o.a. Examples were all between 8 to 10 min.

Claims (1)

-1- 133 313 Invention claim: Process for the continuous purification of wastewater from the polyurethane and / or herbicide production, mixed with an oxygen-releasing or oxygen-containing medium and brought to reaction temperatures between 100 and 300 ^° C., comprising an oxidation catalyst based on from copper oxide, chromium oxide, zinc oxide, manganese oxide or platinum or palladium-filled reactor flows from bottom to top, at a pressure between 3 and 10 MPa, wherein the degradation of toxic and / or poorly degradable wastewater pollution takes place so far that a work-up according to known can connect biological processes, characterized in that as catalysts up to 50% copper oxide on y-alumina and / or magnesium silicate or mixtures of about 4% copper, 7% chromium, 5% zinc oxide or 6% copper, 5% chromium -, 3% manganese oxide or 4% copper, 8% chromium oxide on y-clay or 0.1 to 1% Platinum and / or palladium can be used on γ-alumina.