KR800000607B1 - Process for eliminating reactive chlorinated organic compounds from aqueous solutions - Google Patents

Abstract

Waste warer contg. org. C1 compds., e. g., chloroacetal-dehyde, ∝-chlorocrotonaldehyde, and chloroacetic acid, are treated with NH3, NH4+salt or amines which spilt off Nh3 at the reaction temp. NH3 or NH3-forming reagent is added to the effluent, which usally contains 0.5-15 % C1 compds. the soln. is heated to 70-300≰C, preferably 100-160≰C, at <=10 atms in reactors or reaction pipes batchwise or continuously for 5-60 min. The suspended solids which are formed are nontacky and can be easily removed by conventional sepn. method.

Description

How to remove reactive organochlorine compounds from aqueous solution

The present invention relates to a process for removing reactive organochlorine compounds from aqueous solutions, especially wastewater. In general, industrial wastewater cannot be discharged directly into canals, rivers, lakes or the sea, nor can it be discharged underground without contaminating the above water sources and without contaminating drinking water or plants.

Among such pre-treatment methods of industrial wastewater, which have been frequently practiced in the past, there is a biological decomposition method of organic components by bacteria,

This can be done by an activated sludge treatment plant, i.e., by a spraying method, a disc contactor, an aeration tank or other known method.

In rare cases fungi or yeasts are used in biological degradation methods.

Therefore, undesired industrial wastewater substances which cannot be removed by biological decomposition methods and contain toxic components are pretreated by the appropriate physicochemical methods, ie oxidation, decomposition, precipitation, filtration or evaporation, to the whole or the wastewater. It is completely removed or altered to the extent that some biodegradation is possible.

In such cases, it is desirable to ensure that the wastewater discharged does not exceed the amount of hazardous constituents prescribed by law. The material to be removed is usually expressed in terms of chemical oxygen demand (COD) or biological oxygen demand (BOD), and if a biological treatment plant is needed to obtain a specified value, appropriate pretreatment is required, followed by waste water treatment to remove the load. desirable.

This wastewater contains organic chlorine compounds even though it contains substances that can be decomposed directly by biological treatment.

Such waste waters eventually become aldehydes by the oxidation of ethylene by the “wacker” process. The olefin is oxidized with oxygen to form an aldehyde or ketone in the presence of a platinum compound and water, such as a co-catalyst such as iron or copper salt (see West German Patent No. 1049845, 1080944). .

In addition, this wastewater is mainly deposited in a purified distillation column for producing pure products, and practically contains aldehyde chloride, chloroacetic acid and acetic acid.

The wastewater contains a large amount of untreated compounds in biological treatment plants in addition to some of the substances to be decomposed.

One way to make this wastewater biodegradable is to make it identical to the biological treatment plant by diluting the wastewater 1:20 to 1: 100. However, the above method is only desirable when large biological waste treatment plants are used, where the undecomposed wastewater can be mixed with other wastewaters which are diluted appropriately.

Another method is to chemically pretreat the waste water to make it suitable for the biological treatment plant of the waste. However, to date, there has been no useful way to achieve this goal.

In addition, another object of the present invention is to provide a method for treating wastewater containing an aqueous solution, in particular an organic chlorine compound, by a simple method in order to greatly reduce the chlorine content in the organic chlorine compound and to mainly remove the organic compound. .

According to the present invention, the wastewater is treated mechanically with ammonia or ammonia decomposing compounds at 70-300 ° C., preferably at 100-160 ° C., or with a first amine or a first ammonium decomposing compound or a mixture of these compounds to be mechanically separated from the waste water. The object of the present invention is achieved by obtaining a poorly soluble reaction product.

As a result of the present invention, surprisingly, it was found that the content of chlorine bound to the organic material was almost removed, and the content of the organic material was significantly reduced.

By removing chlorine that is bound to organic matter, wastewater is extremely easy to treat in a biological treatment plant of waste, and by reducing the amount of organic matter, the load on the waste treatment plant is further reduced and the difficult-to-decompose substances are released into the stream. none.

There is also the advantage that the nitrogen needed for the waste treatment plant is present in almost or part of the waste water. The insoluble compound formed in the reaction does not adhere to the surface and does not block the passage of a pipe, a cooler, a measuring instrument, etc., and has a property that can be sufficiently separated.

In addition, since the action with ammonia or amine components can be controlled, only a fixed pH is required.

When only the reactive organic chlorine compound is contained in this aqueous solution, it is also possible to remove almost all organic substances as well as chlorine bound to the organic compound. In the industrial wastewater obtained by the conventional method, i.e., obtained by the above-mentioned waxer method of oxidizing ethylene into acetaldehyde, other organic compounds exist in addition to the organic compounds, and these compounds cannot be removed by the treatment method of the present invention. .

In such industrial wastewater, the COD and BOD values may be reduced by about 20-70% by weight, depending on the reaction conditions and the constituents of the wastewater.

The chemical reaction mechanism is extremely complicated and cannot be explained, but one can be presumed that the amino decomposition action is caused by the action of ammonia or amine, followed by the oligo or poly condensation reaction. Any compound containing an organochlorine compound which acts with ammonia or amine under certain conditions may be used in the aqueous solution which can be treated.

Mixtures of organochlorine compounds, ie mono, di or trichloracetaldehyde, chlorinated aldehydes such as α-chlorcroton aldehyde, chlorocarboxylic acids, ie mono, di or trichloroacetic acid, chlorbutyl acid, and chloramine and chlorinated hydrocarbons It is desirable to.

The content of organochlorine combined with organic compounds in this wastewater is typically 0.5-15 wt%, calculated as wastewater, and the COD value is generally in the range of 5-100 g / l.

In addition, such industrial wastewater may contain other organic compounds, but in general, this wastewater is not disturbed by treatment by the treatment method of the present invention.

On the other hand, such compounds are generally not reduced by the treatment method of the present invention.

As mentioned above, particularly well decomposable wastewater is obtained by a Wacker treatment method in which olefins are oxidized to aldehydes and ketones.

It has already been mentioned that the reagents used for organochlorine compounds are ammonia and ammonia degrading compounds and primary and secondary amine decomposing compounds.

Ammonium salts, such as ammonia decomposing compounds, ie compounds of carbonate chloride, sulphate and phosphate, are technically of note. Most of these compounds or ammonia are added to the wastewater in aqueous solution, but ammonia can also be introduced as a gas. Most of the first amines are aliphatic amines and have a chain length of 1-18 carbon atoms. As examples, methyl, ethyl, propyl, butyl and hexylamine can be listed.

Moreover, di and braamine can be used similarly.

The compound that decomposes the amine is especially hydrochloride, and the amine component can be added to the same aqueous solution or dissolved in another solvent (higher amines) or substance.

In some cases, it is advantageous to react with waste water containing ammonia or amine, and it is preferable to use 0.3-5 moles of ammonia or ammonia decomposition compound, first amine or first amine decomposition compound per mole of organic chlorine.

The reaction is carried out in a conventional reactor, auto clave, vessel, reaction tube or coil at a temperature of 70-300 ° C., preferably at a temperature of 100-160 ° C. and generally at an excess pressure of 0-100 atm, preferably at an excess pressure. It can be done at 0-10atm and can be done continuously or discontinuously.

In general, the continuous reaction is preferably a continuous mechanical removal of the solid material obtained as a result of the reaction, and if it is not heated, the waste water may be preheated to introduce heat required for the reaction into the reactor, and the jacket and The wastewater can be heated by the same indirect or direct heating, such as the introduction of steam, and stirring is smoothly achieved by the latter method.

Ammonia or amines can be added to the reactor or effectively mixed in the reservoir without heating, and the reaction can be carried out by heating in the reactor.

At this time, sufficient mixing is necessary.

In most cases, the agitator is intended to be placed in the reactor. Another method is to install a mixer in the reactor to sufficiently mix the reactive components. The time required for the reaction depends on various variables such as pressure, temperature, concentration of ammonia or amine, component content of waste water,

In general, the reaction time is in the range of 30 seconds to 5 hours, but preferably in the range of 5 minutes to 60 minutes.

After a short time, the wastewater turns brown, and the suspension of solid material is composed of non-adhesive particles, so that the movement proceeds smoothly to the separator. Examples of the separation method include filtration, precipitation, and centrifugation. The pH of the suspension after the reaction is usually 3-10, mostly 5-8, and can be adjusted by addition of ammonia or amine.

In some cases it is advantageous to add coagulants, i.e. aluminum and iron salts (1-1000 ppm / l) and agglomeration media (i.e. polyelectrolytes (0.1-100 ppm / l)) to the suspension produced by the reaction. The reaction allows for better separation of the reaction product. The method of the present invention is specifically described above according to the following examples, but is not limited thereto.

Example 1

Waste water from distillation column of acetaldehyde, pure product produced by ethylene oxidation by Wacker II process, mono, di and trichlor acetaldehyde, α-chlorcroton aldehyde, acetic acid [about 15 wt% of organic substance, about chloric acid 45 g / l (organic chlorine 19.5 g / l, COD35.3 g / l) were contained and the aqueous solution was treated with 25% aqueous ammonia at a molar ratio of chlorine: ammonia = 1: 2.5 while stirring the wastewater at 100 ° C.

시간 반응시킨후, 생성된 갈색의 현탁액을 여과시켰다. (pH=7)

After reacting for a time, the resulting brown suspension was filtered. (pH = 7)

The filtrate thus treated had a value of COD19.6 g / l, which corresponds to a 44% reduction, and no organic chlorine bound to organic matter was detected.

The filtrate diluted to 1:10 was introduced into the activated sludge treatment plant without further pretreatment and without any loss.

Example 2

As in Example 1, the wastewater obtained from the distillation column of pure acetaldehyde has a content of COD35.1g / l and organic chlorine 19.6g / l, and this wastewater is continuously connected to the reactor (iron tube) by a piston-type measuring pump. Passed through.

25% ammonia was added through the second pump so that the molar ratio of organic chlorine: ammonia was 1: 2. Water vapor was directly blown into the reaction chamber, the temperature was maintained at 130 ° C., the pressure was adjusted to an excess pressure of 1.9 atm, and reacted in the reactor for 1 hour.

The continuous discharge on the cooler was pH 6 and after filtering the dendritic material the COD was 21.5 g / l, corresponding to a 39% reduction, with only 1.5 g / l of organic chlorine present in the solution.

Example 3

Distillation to purify the acetaldehyde stock obtained by the Wacker II step treatment yielded a concentrated side stream with 85.2 g / l organochlorine and 145.6 g / l COD, which was then stirred in a stirred flask. It was reacted with ammonia in a molar ratio of organochlorine: NH ₃ = 1: 2 at 100 ° C. for 1 min.

After removing the brown material produced in the reaction, the solution was pH 8 and COD 51.2g / l, which is equivalent to a reduction of 65%. The organic chlorine was present in an amount of 3.7g / l, which was reduced to 95.5%. It was. In practice, the reaction for 2 hours did not change COD any more, while organochlorine was not detected by titration.

Example 4

A dilution of the waste water vapor of Example 3 containing 17.0 g / l of COD29.1 g / l organochlorine was added to diammonium phosphate [(NH ₄ ) ₂ HPO ₄ ] (molar ratio Cl ₂ : NH ₃ ) in a stirred flask at a temperature of 100 ° C. = 1: 2). The molar ratio was controlled by the appropriate amount of diammonium phosphate added.

After reacting for 3 hours, the solution was cooled and the precipitate was filtered off.

No residual organic chlorine was detected in the residual solution and the reduction of COD was 54%.

Example 5

Wastewater of Example 3 containing COD 145.6 g / l and organochlorine 85.2 g / l was treated in a stirred flask with ethylamine at 100 ° C. for 3 hours.

At this time, the molar ratio of ethylamine: organochlorine was 3: 1. The organic chlorine was not contained in the solution obtained by separating the gelled reaction product by the gradient method. The combined 895.g / l COD145.6g / l of the wastewater and 750g / l of the added ethylamine (l calculated as wastewater) was reduced to 166.5g / l or 19% of the total COD.

Example 6

Part of the chlorinated aldehyde was recovered from the wastewater obtained from the distillation column of pure acetaldehyde by the Waxer II stage treatment method to the side stream during distillation, and continuously in the reactor (iron tube) at 100 ° C by a piston-type measuring pump. 25% of ammonia was added in an amount such that the molar ratio of organic chlorine: NH3 = 1: 1.75 was introduced by the second pump.

Here, steam was blown in, and the reactor temperature was maintained at 150 ° C. and the pressure was maintained at an excess pressure of 3.4 atm.

The treated wastewater with the original COD 18 g / l and the organic chlorine 13.7 g / l was subsequently recovered from the reactor on the cooler and filtered.

The COD of the filtrate was 10.9 g / l, corresponding to a 40% reduction and no more organic chlorine.

Claims (1)

A method for removing an organic chlorine compound reacting at a specific temperature from wastewater containing 0.5-15 wt% of organic chlorine, comprising ammonia, a first amine, a compound capable of decomposing the ammonia, and a compound capable of decomposing the first amine. A compound selected from the composed group is reacted with wastewater containing 0.5-15 wt% of organic chlorine at 70 ° C.-300 ° C., preferably 100 ° C.-160 ° C., wherein the molar ratio of organic chlorine and the selected compound is 1: In the aqueous solution characterized in that the insoluble reaction product produced by the reaction is separated by any one of filtration, precipitation and centrifugation by adjusting the pH value of the solution to 3-10, preferably 5-8 after the reaction. Method of removing reactive organochlorine compounds.