JP2748435B2 - Amine-containing wastewater treatment method - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an improved activated carbon treatment method for significantly reducing the wastewater load of amine-containing wastewater.

[Prior art] Generally, in the treatment of wastewater discharged from factories, the target of treatment depends on the type and concentration of pollutants in the wastewater, the type and amount of coexisting substances such as inorganic substances contained in the wastewater, and the wastewater state. The processing method applied and the optimum processing conditions also differ depending on the setting of the density. Amine-containing wastewater is usually subjected to coagulation treatment using an anionic polymer coagulant due to its properties. This method requires an expensive polymer flocculant, and not only cannot recover useful amines in wastewater, but also has a problem in that new treatment of generated sludge is required. When high concentrations of inorganic salts coexist in the wastewater, the coagulation precipitation method cannot be said to be an appropriate treatment method.

Various adsorbent treatment methods have been attempted for amine-containing wastewater. As described in The Chemical Society of Japan 1985 (4) 802, activated carbon has poor adsorption capacity for nitrogen-containing compounds such as ammonia and amines. Silica-titania and silica-titania-magnesia gel have been proposed as highly active adsorbents to overcome the drawbacks of activated carbon. For example, for wastewater containing 100 ppm of amine, these adsorbents have a maximum removal rate of 58%.
%, Which is not sufficiently satisfactory in terms of the removal rate. Further, a composite oxide adsorbent such as silica-titania has an acid property and is easily eluted into a liquid phase by a basic substance such as an amine, and thus has a problem in durability. Japanese Patent Application Laid-Open No. Sho 62-49990 proposes a silica gel adsorbent for overcoming the drawback of poor adsorption performance of activated carbon and activated clay. 20,0
When wastewater containing amine at a high concentration of 00 ppm is treated with silica gel, the removal rate is 57%, and the COD load of the wastewater is inevitably large, which cannot be said to be a sufficiently satisfactory treatment technology.

[Problems to be Solved by the Invention] The present invention uses activated carbon which is industrially available at a low cost, performs an adsorption treatment at a high removal rate, and provides an industrial advanced treatment technology capable of satisfying the following points. It is.

1) A treatment technology that is not affected by the type (chemical structure, molecular weight) and concentration of amine contained in wastewater, that is, can sufficiently cope with fluctuations in wastewater.

2) Achieving a more advantageous removal rate than adsorbent treatment of known titanium oxide, activated clay, silica gel, composite oxide gel, etc.

[Means for Solving the Problem] As a method for reducing the COD load of an amine-containing wastewater, the present inventors have proposed to use an alkali metal hydroxide and / or an alkaline earth metal hydroxide in the wastewater or these metal waters. The present inventors have found a novel fact that the removal rate of amine compounds in wastewater can be remarkably improved by treating with activated carbon in a state where oxides and inorganic salts coexist, and have completed the present invention.

That is, in the present invention, when treating wastewater containing an amine compound with activated carbon, the concentration of alkali metal hydroxide and / or alkaline earth metal hydroxide in the wastewater is 5 × 10 5
^-4 mol / or more in the presence of the above metal hydroxide,
Or contacting with activated carbon in the presence of an inorganic salt and the metal hydroxide so that the concentration of the inorganic salt in the wastewater is 10 g / or more and the concentration of the metal hydroxide is 5 × 10 ⁻⁴ mol / or more. It is a wastewater treatment method.

 Hereinafter, the present invention will be described in more detail.

The amine compound to be treated in the present invention is not particularly limited as long as it is a compound having an amino group in a molecule, and is a wastewater containing an aliphatic amine, an aromatic amine, or the like. For example, alkylamines such as methylamine, dimethylamine, trimethylamine, propylamine, butylamine, and dibutylamine, ethylenediamine, piperazine, triethylenediamine, diethylenetriamine, N-aminoethylpiperazine, triethylenetetramine, and tetraethylenepentane are exemplified as aliphatic amines. Ethyleneamines such as amine and pentaethylenehexamine; polyalkylenepolyamines such as propanediamine, dipropylenetriamine, dimethylaminopropylamine, butanediamine, hesamethylenediamine, and tetramethylhexamethylenediamine; and N-alkylated polyalkylenepolyamines And oxygen-containing aliphatic amines such as morpholine, ethanolamine and aminoethylethanolamine. Examples of aromatic amines and heterocyclic compounds include aniline, aminotoluene, phenylenediamine, pyridine, picoline, pyrazine, and alkylparazine. The amine compound in the wastewater may exist as a single compound, or may exist in a mixed state of various amine compounds, or may be in a state where other alkanes, alkenes, and aromatics coexist with the amine. Even this is a processing target of the present invention.

The amine concentration in the wastewater to which the present invention can be applied is not particularly limited, but usually 10 to 100,000 ppm of amine-containing wastewater is treated. Even with high concentration amine-containing wastewater of 100,000 ppm or more, it can be treated at a high removal rate by the method of the present invention, but considering the load at the time of recovery of adsorbed amine, it is not necessarily economically advantageous wastewater treatment. It is not a law.

As the alkali metal hydroxide and alkaline earth metal hydroxide used in the present invention, lithium hydroxide, sodium hydroxide, potassium hydroxide, cesium hydroxide and calcium hydroxide are useful. The metal hydroxide concentration is preferably 2 × 10 ^-4 mol / or more in the wastewater, preferably 2 × 10 ^-4 mol / mol.
After adding the metal hydroxide so as to have a concentration of 10 ⁻³ mol / or more, it is important to treat with activated carbon. If the concentration of the metal hydroxide in the wastewater is 5 × 10 ⁻⁴ mol / or less, the amine removal rate is lowered, and it is difficult to achieve the intended advanced wastewater treatment. The optimum concentration of the metal hydroxide in the wastewater varies depending on the properties of the wastewater, and may be appropriately adjusted.

By keeping the concentration of the metal hydroxide in the wastewater at a certain level or higher and simultaneously coexisting with an inorganic salt, it is possible to synergistically improve the amine removal rate in the wastewater. The type of the inorganic salt is not particularly limited. Alkali metal, alkaline earth metal ions, etc. are selected as the cation portion of the inorganic salt, and halogen ions, sulfate ions, carbonate ions, etc. are selected as the anion portion, and secondary pollution is caused according to the waste water condition. Inorganic salts that do not are added. For example, sodium chloride, calcium chloride, sodium sulfate,
Examples include sodium carbonate, sodium bromide, calcium bromide, and cesium chloride. The concentration of these inorganic salts is adjusted to 10 g / or more, preferably 50 g / or more, in the waste water, and then treated with activated carbon. I want it. When the concentration of the inorganic salt in the wastewater is 10 g / or less, the effect of improving the amine removal rate is extremely small. In the dichloroethane ethyleneamine production process, hydrochloric acid generated from the reaction step is neutralized by an alkali metal hydroxide or an alkaline earth metal oxide to form an alkali metal chloride or an alkaline earth metal salt. In discharging the aqueous solution containing by-product salt, the concentration of alkali metal hydroxide and / or alkaline earth metal hydroxide in the aqueous solution of amine-containing by-product salt is 5 × 10 ⁻⁴ mol / or more. If the activated carbon treatment is performed in such a state that these metal hydroxides coexist, a high amine removal rate can be achieved. The metal salt hydroxide may be added in an excess amount relative to the neutralization equivalent in the neutralization step of the production process, or may be added before the activated carbon treatment.

As the activated carbon used in the present invention, any of charcoal, coal and coconut shell charcoal, which are used as general adsorbents and water treatment agents, can be effectively used. Among them, in the treatment method of the present invention, coconut shell charcoal is extremely useful industrially. The form may be granular or powdery.

The wastewater treatment method using activated carbon can be applied to the present invention in any of a batch method and a continuous fixed bed method. An industrially advantageous method is selected depending on the amount of wastewater to be treated, the scale of the treatment facility, and the like. The contact temperature between the wastewater and the activated carbon is carried out below the boiling point of water, but the wastewater having low viscosity is usually treated at 70 ° C or less. The treatment time in the batch method varies depending on the properties of the wastewater and the amount of activated carbon, but the contact equilibrium is reached by contacting for 15 minutes to 24 hours. The liquid passing rate in the fixed bed flow system largely depends on properties such as the amount of amine contained in the wastewater and the molecular weight of amine. Usually 0.1 to 20m / h
The liquid is passed at a linear velocity of r. Although processing can be performed even at a linear velocity of 20 m / hr or more, the concentration of amine leaking into the processing solution is undesirably increased.

[Effects of the present invention] By applying the method of the present invention to the activated carbon treatment of amine-containing wastewater, the amine concentration in the treated liquid is significantly reduced, and the amine removal rate can be maintained at an extremely high level, enabling advanced wastewater treatment. It became. In addition, since the amine adsorption capacity of the activated carbon is increased, the regeneration cycle of the activated carbon is reduced and the operation of the plant becomes easier. Generally, it is known that properties of wastewater change. For example, in an ethyleneamine production plant, the amine concentration in wastewater discharged from the plant and the composition of the type of amine (ethylenediamine, diethylenetriamine, triethylenetetramine, etc.) change depending on the plant operating conditions. The method of the present invention is characterized in that it can stably maintain a high level of wastewater treatment while allowing fluctuations in the state of wastewater. Industrial plants that produce useful amine compounds by reacting halogenated organics with ammonia or amines are versatile. These plants usually emit inorganic salts along with the amine. Applying the method of the present invention to such wastewater treatment results in a synergistic increase in the amine adsorption capacity on activated carbon, and is a very effective wastewater treatment technique.

For wastewater having the properties targeted by the present invention, among activated carbons, those of coconut shell charcoal have a large adsorption capacity,
This is extremely advantageous for the operation management of the processing plant.

EXAMPLES Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples.

Examples 1 to 12 and Comparative Examples 1 to 3
Of activated carbon 1 shown in FIG. Liquids obtained by adding various alkali metal hydroxides or alkaline earth metal hydroxides to wastewater having different properties (types and amounts of amine compounds) shown in Table 1 so as to have a predetermined concentration were added to a column packed with activated carbon at 1.5 /
The liquid was passed at the hr supply rate. The adsorption operation was performed at 40 ° C. The distillate was sampled at regular intervals, and the concentration of organic substances in the liquid was measured in all organic carbon systems. Table 1 shows the concentration of organic substances contained in the processing solution at the time when the solution flowed out by a predetermined amount.

In Comparative Examples 1 to 3, the liquid was passed through the activated carbon packed column in the same manner as in Example 1 without adding any alkali metal hydroxide or alkaline earth metal hydroxide to the wastewater.

Examples 13-26, Comparative Examples 4-14 100 ml of amine-containing wastewater shown in Table 2 in a 300 ml Erlenmeyer flask
And if necessary, alkali gold Addition and adjustment of the metal hydroxide or the alkaline earth metal hydroxide to a predetermined concentration. Next, 1 g of activated carbon (powder) or acidic oxide (granular 2 to 4 mm) shown in Table 2 was added, and the mixture was shaken on a 30 ° C. water bath for 2 hours (24 hours for an acidic oxide).
Thereafter, the activated carbon was separated and removed, and the amine concentration in the solution was measured in the total organic carbon system. The results are shown in Table 2 as the amine concentration after treatment and the amine adsorption amount.

Claims (5)

(57) [Claims] 1. The method of claim 1, wherein the amine-containing wastewater is used in an amount of 5 × 10 ⁻⁴ to 4 × 10 ⁻² mo
A wastewater treatment method characterized by contacting with activated carbon in the presence of l / l alkali metal hydroxide and / or alkaline earth metal hydroxide. 2. The method according to claim 1, wherein the amine-containing wastewater is treated with an inorganic salt of 10 g / l or more,
And a wastewater treatment method characterized by contacting with activated carbon in the presence of 5 × 10 ⁻⁴ to 4 × 10 ⁻² mol / l alkali metal hydroxide and / or alkaline earth metal hydroxide. 3. The method according to claim 1, wherein the amine is ethyleneamine. 4. The amine-containing wastewater according to claim 2, wherein ethyleneamine produced by a dichloroethane process for producing ethyleneamines by reacting dichloroethane with ammonia is mixed with ethyleneamine and salt. The method described in the section. 5. The method according to claim 1, wherein the activated carbon is coconut shell activated carbon.