KR100244971B1 - A waste water treating method using sodium chloride separation process - Google Patents

Abstract

The present invention relates to a method for treating waste liquid using separation of salt. More specifically, the waste liquid from the hydroxylpropyl methylcellulose manufacturing process is evaporated at low temperature in a distillation preheating tank in a multi-stage condensing system, and the low-boiling organic matter condensed is incinerator. The condensate from the concentrations of the first and second concentration tanks is treated by biological method, and the resulting salt is treated as solid waste through a centrifuge. By incineration, it relates to a waste liquid treatment process that can minimize the incineration material to reduce the treatment cost of waste liquid.

Description

Wastewater Treatment Process Using Salt Separation Process

The present invention relates to a method for treating waste liquid using separation of salt. More specifically, the waste liquid from the hydroxylpropyl methylcellulose manufacturing process is evaporated at low temperature in a distillation preheating tank in a multi-stage condensing system, and the low-boiling organic matter condensed is incinerator. The condensate from the concentrations of the first and second concentration tanks is treated by biological method, and the resulting salt is treated as solid waste through a centrifuge. By incineration, it relates to a waste liquid treatment process that can minimize the incineration material to reduce the treatment cost of waste liquid.

The waste liquid generated in the hydroxylpropyl methyl cellulose manufacturing process is a malignant waste liquid containing a large amount of water-soluble organic substances and salts having -OH functional groups such as hemicellulose and propylene glycol.

Conventionally, the entire waste solution was incinerated to treat the waste solution, but the amount of the waste solution is increased as well as the content of the inorganic salt is about 10% by weight, which may cause secondary environmental problems such as dust generation. Therefore, there is a problem in that a method such as additional installation of a dust collector for reducing the amount of incineration or removing dust is required.

Such waste liquid generating process is shown in Figure 1 of the accompanying drawings, the process will be described in detail as follows.

The pulp, which is the main raw material of cellulose, is pulverized in the pulp mill (1), sent to the pulp silo (3) through the pulp filter (2), and then introduced into the reactor (4). In the reactor, pulverized pulp and raw materials such as caustic soda are mixed to produce hydroxylpropylmethylcellulose.

The filtrate is generated as waste liquor 11 through the press filter 5 and the remainder is made into the product via the blender 6, the granulator 7 and the dryer 8. At this time, the waste liquid generated from the press filter 5 is directly sent to an incinerator for incineration.

Thus, incineration of the waste liquid generated in the related art can cause secondary environmental problems such as excessive expenditure of waste treatment costs and the inclusion of dust in the exhaust gas after incineration. Therefore, there is an urgent need to secure a technology for minimizing incineration materials to reduce waste disposal costs and to reduce secondary environmental pollution.

Therefore, in the present invention, by distilling and concentrating the waste liquid generated in the hydroxylpropyl methyl cellulose manufacturing process to improve the above problems, by reducing the amount of incineration, by removing inorganic salts such as salt from the incineration target material The purpose is to minimize the occurrence of dust and the like.

1 is a schematic diagram of a hydroxylpropyl methyl cellulose production process before the introduction of the salt separation process.

2 is a schematic diagram of a hydroxylpropyl methyl cellulose production process after the introduction of a salt separation process.

* Explanation of symbols for main parts of the drawings

1: pulp mill 2: pulp filter

3: pulp silo 4: reactor

5: press filter 6: blender

7: granular 8: dry

9: raw material 10: product

11: waste liquid 12: distillation preheating tank

13a: first distillation tank 13b: second distillation tank

14 condensing tank 15 organic matter removing tank

16: filter 17: salt

18: Filtrate 19: Hopper

20: low boiling point organic matter discharge line 21: incinerator

22: biological treatment plant wastewater 23: recycling

Therefore, in the present invention, in treating the waste liquid generated during the hydroxylpropyl methyl cellulose manufacturing process, the low-boiling organic matter in the waste liquid is removed from the distillation preheating tank 12, and the waste liquid from which the low-boiling organic matter is removed is removed from the first distillation concentration tank 13a. After concentration in the second distillation tank (13b) and distilled low-boiling organic matter is removed in the organic material removal tank 15, the concentrated waste liquid is filtered through a filter (16) at this time the precipitated salt is recovered to the hopper (19) It relates to a waste liquid treatment process generated in the hydroxylpropyl methyl cellulose production process characterized by incineration of the filtered waste liquid in the incinerator (21).

In this case, the distillation preheating tank 12 is characterized in that the low boiling point organic material is selectively separated and removed under 45 to 65 ° C. temperature and 300 to 500 mmHg pressure, and then used as the fuel of the incinerator. The low-boiling point organic matter contained in the condensed water evaporated and condensed in the 13a and the second distillation tank 13b is passed through the organic matter treatment tank 15 for biological treatment.

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

When explaining the configuration of the present invention, distillation preheating tank 12 for removing the low-boiling point organic matter of the waste liquid generated during the hydroxylpropyl methyl cellulose manufacturing process; A first distillation tank (13a) and a second distillation tank (13b) for firstly concentrating the waste liquid from which the low boiling point organic matter has been removed; An organic material removing tank 15 for removing high-boiling organic matter distilled from the first and second distillation concentration tanks 13a and 13b; A filter (16) for filtering the concentrated concentrate; A hopper 19 through which filtered residue is sent; And it consists of a configuration including an incinerator 21 for incineration of the filtered waste liquid is configured to separate the salt from the waste liquid (11).

It is characterized by having a distillation preheating tank, a multi-stage distillation tank, a filter, etc., between the waste liquid 11 and the incinerator 21 coming out of the press filter 5.

Referring to the waste liquid treatment process using the separation of salt of the present invention as described in detail based on Figure 2 as follows.

The waste liquid from the press filter 5 is sent to the distillation preheating tank 12 through the waste liquid injecting line, and some low boiling organic matters having a boiling point of 60 ° C. or lower from the distillation preheating tank 12 are passed through the low boiling point organic matter discharge line 20. After distillation, the waste liquid 11 is concentrated in the first distillation tank 13a. The waste liquid concentrated in the first distillation tank 13a is re-concentrated in the second distillation tank 13b after entering the second distillation tank 13b through a moving line between the distillation tanks for better incineration treatment. At this time, in order to facilitate the distillation concentration and increase the efficiency, a pressure reduction distillation method is used. In addition, it is recommended to use an antifoaming agent at this time because the contained material may be foamed when the temperature is increased or reduced pressure. The water distilled in the first distillation tank 13a and the second distillation tank 13b is sent to the organic matter removal tank 15 because it contains a small amount of low boiling point organic matter. Here, the organic matter is sent to the low boiling point organic matter discharge line 20 in a gaseous state in the same process as the method of removing the organic matter distilled from the first distillation tank, and most of the remaining condensate water is sent to the biological treatment plant 22.

On the other hand, the concentrated waste liquid remaining without distillation from the second distillation concentration tank 13a to the organic matter removal tank 15 is sent to the filter 16 and filtered. The filtrate injected into the filter is a state of precipitation of salt. Pressure filtration, or pressure filtration or centrifugation, is used for smooth filtration. Since the filtered salt 17 is a soluble substance that can be easily dissolved in water, it is sent to the hopper 19 to be landfilled with solid waste. However, the filtrate passing through the filter 16 is fed back into the second distillation tank 13b via the recycle line 23 and then concentrated again. The waste liquid introduced into the second distillation tank 13b through the recirculation line 23 is concentrated, and the precipitated salt and the concentrated waste liquid are sent to the filter 16 again. After the concentrated waste liquid is filtered again in the filter 16, the salt after filtering is landfilled as solid waste in the hopper 19, and the filtrate in the filter 16 is sent to the incinerator 21.

In the present invention, since the incineration amount is reduced by using a multi-step concentration process and a salt separation process, the waste liquid generated in the hydroxylpropylmethylcellulose manufacturing process has an effect of reducing secondary environmental pollution generated during incineration.

In the treatment of the wastewater of the hydroxylpropyl methyl cellulose manufacturing process, an important process for effectively reducing the amount of incineration is a process in which water and a small amount of organic matter, which occupy 80% by weight of the waste, are removed by distillation, and salts are separated and separated. Is in. When concentrated and separated well, the incineration amount is reduced to about 10% by weight. When most of the water is distilled off, the amount of incineration is reduced in the incineration method, and if the salt is separated and removed, it is possible to prevent secondary environmental pollution such as dust generation.

Hereinafter, the present invention will be described in detail with reference to Examples. The present invention is not limited by the examples.

Example

The composition of the waste liquid from the hydroxylpropyl methyl cellulose manufacturing process is shown in Table 1 below. When the waste liquid has a composition as shown in Table 2 below, the waste liquid is added to the distillation preheating tank 12 shown in FIG. Here, the material having a boiling point of 60 ° C. or less is distilled under conditions of 60 ° C. and 450 mm Hg, and then low-boiling organics flying in a gaseous state are sent to the incinerator through the low-boiling organics discharge line 20, and the waste liquid removed from the low-boiling organics is first distilled. It is sent to the concentration tank 13a. In the first distillation tank (13a) is concentrated to about 30% under the conditions of 70 ℃, 300mmHg. At this time, the distilled water is sent to the biological treatment plant 22, and the concentrated liquid is passed to the second distillation concentration tank 13b. The concentrated waste liquid is concentrated again in the second distillation tank at the condition of 65 ° C. and 250 mm Hg to precipitate salt. The water distilled by the same process as in the first distillation concentration tank 13a goes to the biological treatment plant 22, and the concentrated liquid in which the salt is precipitated is sent to the filter 16. The salt is separated using centrifugation in the filter. At this time, the filtrate containing the supersaturated salt is sent back to the second distillation tank (13b) through the recycle line (23). The salt is almost completely removed and the separated filtrate 18 is sent to an incinerator 21 for incineration.

[Table 1] Composition of General Waste Liquid

[Table 2] Composition of Waste Liquid in the Example

Wastewater, which was completely incinerated in the present invention, was used to reduce the amount of incineration by using a continuous evaporation and salt separation process, thereby solving the secondary environmental pollution problem. By using the evaporation concentration process and the salt separation process, the incineration amount is reduced to about 10% of the original waste liquid, and the secondary environmental pollution due to incineration, including the biological treatment of the waste liquid by reducing the environmental load and effect It can be seen that there is an effect of reducing the waste disposal cost.

Claims (1)

The low-boiling organic matter in the waste liquid is selectively separated under a 45-65 ° C. temperature of 300-500 mmHg pressure to remove it from the distillation preheating tank 12, and the waste liquid from which the low-boiling organic matter is removed is removed from the first distillation concentration tank 13a and the second distillation concentration tank ( The low-boiling organic matter contained in the condensate after evaporation and condensation in 13b) is passed through the organic matter treatment tank 15 for biological treatment, and then the concentrated waste liquid is filtered through the filter 16, and the precipitated salt is recovered to the hopper 19. And injecting the filtered waste liquid in the incinerator (21).

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