JPH11114552A - Method for recovering valuable materials from organic waste liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively separate and recover valuable materials from an org. waste liq. by adding an alkali to the waste liq., gasifying ammonia by aeration, adding an org. solvent to the liq. freed from ammonia to extract inorg. salts and heating the liq. from which the inorg. salts are removed to volatilize off and separate the org. solvent. SOLUTION: The org. waste liq. is admixed with an alkali in a mixing tank 1 and brought into countercurrent contact with air in a stripping tower 2, and the ammonia ion in the org. waste liq. is separated as gaseous ammonia. The gaseous ammonia obtained is reacted with an aq. inorg. acid soln. in an absorption tower 3 and recovered in a storage tank 4 as an aq. soln. of inorg. acid ammonium. Meanwhile, to the effluent of the stripping tower 2 an org. solvent is added in a salting-out tank 5, the inorg. salt is separated and removed by the salting-out effect, and the inorg. salt is dehydrated by a centrifugal separator 6 and then charged into a storage tank 7. The supernatant water of the salting- out tank 5 is preheated by a heat exchanger 8 and then heated by a vaporizer 9, the org. solvent is volatilized off, and the concd. org. matter soln. is stored in a storage tank 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recovering valuable resources from organic waste liquids such as food fermentation waste liquids, and more particularly, to treating organic waste liquids containing ammonia ions, inorganic acid ions and organic substances. The present invention relates to a method for efficiently separating and recovering ammonia, inorganic salts, and organic substances in water.

[0002]

2. Description of the Related Art Conventionally, organic waste liquid is generally treated by diluting the waste liquid and using a so-called water treatment technique such as methane fermentation or activated sludge treatment, or by burning a concentrated waste liquid as it is. Have been.

In such a method of treating an organic waste liquid, only heat is utilized by combustion, and it has not been possible to separate and recover components in the waste liquid for effective use.

Japanese Patent Publication No. 5-25276 proposes a method of treating organic sludge by decomposing sludge at high temperature and pressure and recovering fuel with an organic solvent.
Only the flammable liquid was recovered, and other components could not be separated and recovered.

[0005]

In recent years, reduction in volume of waste and effective reuse of resources have been required in all industrial fields, and even when treating organic waste liquids, valuable resources contained therein are separated and recovered. It is strongly desired to do so.

The present invention has been made in view of the above-mentioned conventional circumstances, and provides a method for efficiently separating and recovering valuable resources from an organic waste liquid containing ammonia ions, inorganic acid ions, and organic substances. With the goal.

[0007]

According to the present invention, there is provided a method for recovering valuable resources from an organic waste liquid, the method comprising recovering valuable resources from an organic waste liquid containing ammonia ions, inorganic acid ions and organic substances. After adding the alkali, an ammonia stripping step of gasifying ammonia by aeration, an ammonia absorbing step of contacting the gasified ammonia with an inorganic acid aqueous solution to absorb ammonia, and an effluent of the ammonia stripping step An inorganic salt is precipitated by contacting with an organic solvent, and an inorganic salt separating and recovering step of separating and recovering the precipitate, and the separated solution in the inorganic salt separating and recovering step is heated to vaporize and separate the organic solvent and collect the organic matter solution. An organic matter recovery step to be performed, and a step of liquefying the organic solvent vaporized in the organic matter recovery step and sending the liquefied organic solvent to the inorganic salt separation and recovery step. And no liquefaction, characterized in that it comprises a said inorganic salt separation and recovery sent to step Kyusuru process.

An inorganic solvent can be efficiently separated by adding an organic solvent to the solution from which ammonia has been removed to lower the solubility of the inorganic salt and performing salting out. The organic substance can be recovered at a high concentration by vaporizing and separating the organic solvent from the liquid from which the inorganic salt has been removed.

In the present invention, the recovered inorganic salt is electrolyzed to generate an inorganic acid and an alkali, and the generated inorganic acid is sent to an ammonia absorbing step and the alkali is sent to an ammonia stripping step. Is preferred.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a system diagram showing an embodiment of the method for recovering valuable resources from organic waste liquid according to the present invention.

FIG. 1 shows a case where an organic waste liquid containing sulfate ions (SO ₄ ²⁻ ) as inorganic acid ions is treated with sodium hydroxide (NaOH) as alkali. The method is not limited to this method, and the type of inorganic acid ions in the organic waste liquid is not particularly limited.

First, the organic waste liquid is alkali (N) in a mixing tank 1.
aOH) to adjust the pH to about 10-12,
By bringing the stripping tower 2 into countercurrent contact with air, ammonia ions in the organic waste liquid are separated as ammonia gas.

In the method of FIG. 1, NaOH obtained by electrolyzing an inorganic salt (Na ₂ SO ₄ ) obtained in the subsequent salting-out tank 5 with an electrolyzer 11 is used as the alkali. An external alkali may be used.

The ammonia gas obtained in the stripping tower 2 is reacted with an aqueous solution of an inorganic acid (H ₂ SO ₄ ) in the absorption tower 3 and is recovered in the storage tank 4 as an aqueous solution of an ammonium ammonium ((NH ₄ ) ₂ SO ₄ ). . The amount of the inorganic acid aqueous solution may be about the theoretical amount of inorganic acid ammonium.

In the method shown in FIG. 1, this inorganic acid aqueous solution is used as the inorganic salt (Na ₂ SO ₄ ) obtained in the subsequent salting-out tank 5.
H ₂ SO ₄ obtained by electrolyzing the compound in the electrolyzer 11 is used, but an inorganic acid aqueous solution from outside the system may be used.

On the other hand, the effluent of the stripping tower 2 is added with an organic solvent in the salting-out tank 5, and the inorganic acid ions (SO ₄ ²⁻ ) in the organic waste liquid and the alkali (N ² ) added in the mixing tank 1 are added.
NaOH) and the resulting inorganic salt by reaction (Na ₂ SO ₄₎ is separated off by salting out.

The amount of the organic solvent to be added depends on the concentration of the inorganic salt, the type of the inorganic salt, the type of the organic solvent, the treatment temperature, etc.
It is preferred to be about 0 to 120% by volume.

In the present invention, as the organic solvent, the organic solvent separated in the latter vaporizer 9 is circulated and used. As the organic solvent, methanol, ethanol, diethylene glycol monomethyl ether and the like can be used.

The inorganic salt (Na ₂ SO) separated in the salting-out tank 5
₄ ) After the sludge is dehydrated by the centrifugal separator 6, it is put into the storage tank 7 to become an inorganic salt (Na ₂ SO ₄ ) aqueous solution.

This aqueous solution of an inorganic salt (Na ₂ SO ₄ ) is introduced into an electrolyzer 11 and electrolyzed into an acid (H ₂ SO ₄ ) and an alkali (NaOH). Water (H ₂ O) generated by the electrolysis is returned to the storage tank 11.

The supernatant water from the salting-out tank 5 is introduced into a heat exchanger 8 and is preheated by heat exchange with an organic solvent vaporized in a next vaporizer 9 and then heated in the vaporizer 9 to vaporize the organic solvent. Separated. Usually, this heating temperature is about 90 to 95 ° C. The organic solvent vaporized in the vaporizer 9 is cooled in the heat exchanger 8 and then sent to the salting-out tank 5.

The organic substance solution in which the organic substance is concentrated by vaporization and separation of the organic solvent is stored in a storage tank 10. This organic substance solution is a solution mainly composed of organic substances obtained by removing ammonia ions and inorganic acid ions from the organic waste liquid and further concentrating the organic substances, and can be reused as a fertilizer, a raw material for feed, and the like.

In the method for recovering valuable resources from the organic waste liquid of the present invention, the method for recovering 10,000 mg of ammonia ions
/ L or more, especially 30,000-60,000 mg / L
About 25,000 inorganic acid ions such as SO ₄ ²⁻ and Cl ^{2 −.}
0 mg / L or more, especially 75,000 to 150,000 m
g / L, and 20,000 mg / TOC of organic matter as TOC.
L or more, especially about 60,000 to 120,000 mg / L, which is extremely effective in separating and recovering and reusing valuable resources from food production waste liquids such as food fermentation waste liquids, food production waste liquids such as seasonings, pharmaceutical production waste liquids, and the like. It is.

[0025]

The present invention will be described more specifically with reference to the following examples.

Example 1 The following organic wastewater having the following water quality (fermentation wastewater from the amino acid production process) was treated by the method shown in FIG.

The organic waste water _{TOC: 110,000mg / L SO 4:} 138,000mg / L NH 4 -N: 56,000mg / L is first introduced to the mixing tank 1 the organic wastewater at a flow rate of 35L / min 20% by weight from the subsequent electrolyzer 11
NaOH aqueous solution is added at a rate of 20 L / min to adjust pH.
Was set to 11, and 55 L / min was added to the stripping tower 2.
And ammonia was gasified at an air ventilation rate of 160 m ³ / min. The ammonia gas is fed to the absorption tower 3 and is absorbed by a 25% by weight aqueous H ₂ SO ₄ solution 25 L / min from the subsequent electrolyzer 11 to obtain a 26% by weight (N
An aqueous solution of H ₄ ) ₂ SO ₄ was obtained.

The effluent of the absorption tower 3 is supplied to the salting-out tank 5 at 35 L / m.
in, the organic solvent (ethanol) from the heat exchanger 8 at the subsequent stage was added at 35 L / min, and Na ₂ S was added at 20 ° C.
O ₄ sludge of 14 kg / min was obtained. The precipitate was concentrated in a centrifuge 6 and then introduced into a storage tank 7. In the storage tank 7, ₆ L / min of H ₂ O is circulated from the electrolysis device 11, and the concentration of Na ₂ SO ₄ in the tank is adjusted to 35% by weight.

The 35% by weight aqueous solution of Na ₂ SO ₄ contains 13
L / min to the electrolyzer 11 and Na ₂ SO
₄ is electrolyzed into H ₂ SO ₄ and NaOH and sent to the absorption tower 3 and the mixing tank 1, respectively. The electrolyzer is supplied with 30 L / min of H ₂ O.

The effluent 63 L / min of the salting-out tank 5 is preheated to 80 ° C. in the heat exchanger 8 and then 95 ° C. in the vaporizer 9.
And the organic solvent contained therein is removed and concentrated. The organic substance solution 30 L / min concentrated in the vaporizer 9 is stored in the storage tank 10. On the other hand, the organic solvent is cooled by heat exchange in the heat exchanger 8 and then returned to the salting-out tank 5.

By this treatment, the following organic substance solution having the following water quality was obtained at a ratio of 0.86 t / t to the organic waste liquid of the raw water.

Organic matter solution water quality TOC: 180,000 mg / L SO ₄ : 8,000 mg / L NH ₄ —N: 300 mg / L The amount of recovered Na ₂ SO ₄ is 0.17 t with respect to the organic waste liquid of raw water. The recovery was 90% in / t.

[0033]

As described in detail above, according to the method for recovering valuable resources from organic waste liquid of the present invention, ammonia ions,
Valuables can be efficiently separated and recovered from the organic waste liquid containing inorganic acid ions and organic substances, and their effective use can be achieved.

In particular, according to the method of the second aspect, an efficient treatment can be performed using the inorganic salt recovered in the system.

[Brief description of the drawings]

FIG. 1 is a system diagram showing an embodiment of a method for recovering valuable resources from organic waste liquid of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mixing tank 2 Stripping tower 3 Absorption tower 4,7,10 Storage tank 5 Salting-out tank 6 Centrifuge 8 Heat exchanger 9 Vaporizer 11 Electrolyzer

Claims (2)

[Claims] 1. A method for recovering valuable resources from an organic waste liquid containing ammonia ions, inorganic acid ions and organic substances, comprising: adding an alkali to the waste liquid, and gasifying ammonia by aeration, followed by an ammonia stripping step; An ammonia absorption step of bringing gasified ammonia into contact with an aqueous solution of an inorganic acid to absorb ammonia; and contacting the effluent of the ammonia stripping step with an organic solvent to precipitate an inorganic salt, and separating and collecting the precipitate. An inorganic salt separation and recovery step, an organic material recovery step of heating the separated liquid of the inorganic salt separation and recovery step, vaporizing and separating the organic solvent and recovering an organic substance solution, and liquefying the organic solvent vaporized in the organic substance recovery step, Feeding the waste to the inorganic salt separation and recovery step. 2. The method according to claim 1, wherein the inorganic salt recovered in the inorganic salt separation and recovery step is electrolyzed to generate an inorganic acid and an alkali, and the inorganic acid is supplied to the ammonia absorption step. And recovering valuable resources from the organic waste liquid by feeding alkali to the ammonia stripping step.