JPH11226560A - Waste liquid or wastewater treatment method and apparatus - Google Patents

Abstract

(57) [Summary] [Problem] To remove alcohol distillation residue waste liquid in alcohol brewing, alcohol remains, and wastes of fermentation raw materials such as wheat and potato are contained as solids, and also other organic substances are contained. This waste liquid treatment is an issue. Therefore, the main purpose is to remove alcohol by using a general operation called rectification to remove organic substances in waste liquid. Biological oxygen demand, which is an indicator of residual organic matter, can be reduced, and alcohol can be recovered as useful, although containing impurities.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and method for treating waste liquid (including waste water) containing volatile organic substances such as brewery waste liquid.

[0002]

2. Description of the Related Art As a conventional technique for treating a waste liquid having a high biological oxygen demand (hereinafter referred to as BOD), there is a method of reducing BOD by anaerobic fermentation (methane fermentation) using methane bacteria. There is also a method of lowering the BOD by aerobic treatment using a special bacterium.

[0003] For example, the waste liquid after alcohol distillation in alcohol brewing is mostly water, but has a high BOD because it contains a small amount of residual alcohol and other by-products in addition to solids called lees. Is shown. The vapor condensate obtained by evaporating the waste liquid also contains a volatile component such as alcohol, and thus exhibits a high BOD. As an example of such a waste liquid treatment method, there is a method shown in FIG.

In the method shown in FIG. 7, the waste liquid is separated into a cake part mainly composed of solids and a filtrate part by a centrifuge 51, and the filtrate part obtained by this separation is evaporated by a concentrator 53.
The thermal energy of the exhaust gas obtained when the cake part is incinerated is used as the thermal energy for evaporating the filtrate. The concentrated liquid is incinerated together with the cake portion in the incinerator 55. The evaporative vapor condensate is reduced in BOD by the anaerobic water treatment device 57 using methane bacteria, and then the final water is discharged in the aerobic water treatment device 59 by the activated sludge method. Processing is in progress. Thus, the evaporative vapor condensate contains alcohol and other volatile by-products and has a high BOD of 10,000 to 30,000 ppm, requiring special microbial treatment.

[0005]

The treatment method using these microorganisms requires a long initial cultivation time of the microorganisms until the treatment can be carried out. Even after the treatment is started, a nutrient source which is insufficient for the growth of the microorganisms may be added or treated. There are problems such as a change in the BOD in the medium or difficulty in controlling the microorganisms when not treating.

It is an object of the present invention to provide a waste liquid treatment method and apparatus capable of reducing BOD without depending on treatment of waste liquid having a high BOD by microorganisms.

[0007]

According to the present invention, separation by rectification is performed as a basic configuration. A waste liquid having a high BOD is rectified by a rectification column, and an organic substance having a lower boiling point than water is extracted as a distillate from the column as a distillate while containing water, and a bottom liquid having a low BOD can be obtained from the column bottom.

[0008] The operation called rectification is a general method used for fractionating low-boiling substances and high-boiling substances. A low-boiling substance is taken from the top of the rectifying column and a high-boiling substance is taken from the bottom of the rectifying column. It is an operation to separate. It is used for extracting pure substances and refining petroleum, but it has never been used to reduce BOD in wastewater or wastewater with high BOD.

The present invention relates to B containing an organic substance having a boiling point lower than that of water.
Rather than rectifying the waste liquid having a high OD by the rectification tower to organic substances having a boiling point lower than that of water in a pure state, by separating it from the top of the rectification tower as a distillate containing water, Reduce the organic matter content in the bottoms, and
The aim is to lower the OD.

When an organic substance having a boiling point lower than that of water is contained in a waste liquid having a high BOD, the organic substance having a boiling point lower than that of water is collected preferentially at the top of the column if it is rectified in a rectification column. However, if water is included, other organic substances are also included due to the equilibrium relationship of the vapor pressure. Any organic substance that forms an azeotrope with an organic substance having a boiling point lower than that of water is also included in the distillate. As a result, those organic substances are reduced in the bottom product in the bottom, and the BOD is reduced.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of a waste liquid treatment apparatus suitable for treating waste liquid after alcohol distillation in alcohol brewing.

In the method shown in FIG. 1, the waste liquid is separated into a cake part mainly composed of solids and a filtrate part by a centrifugal separator 51, and the filtrate part is evaporated by a concentrator 53. The thermal energy of the exhaust gas from the incineration of the cake is used as the thermal energy for evaporating the filtrate. The concentrated liquid is incinerated in the incinerator 55 together with the cake part.
The configuration up to this point is the same as the conventional method described above with reference to FIG. In the present invention, the evaporated vapor condensate is collected by the rectification column 61.
By taking out a distillate containing ethyl alcohol and also containing water and other organic substances from the top of the column, a bottom product having a reduced BOD containing almost no ethyl alcohol is obtained from the bottom of the column. The distillate contains water and other organic substances, but contains a large amount of ethyl alcohol. Therefore, the distillate is recovered as a crude alcohol, and the bottoms are finally treated with an aerobic water treatment apparatus 59 using an activated sludge method as in the conventional method to further reduce the BOD. Perform water treatment.

The method shown in FIG. 2 is the same as the example of FIG. 1 except that the vapor evaporated from the concentrator 53 is supplied directly to the rectification column without being condensed.

FIG. 3 shows a specific example of FIG. 1 as a specific example of FIG.

In the alcohol brewing, the waste liquid containing the solid content of the distilled cake after alcohol distillation is separated by a centrifugal separator 1 into a filtrate tank 2 and a cake part mainly composed of solids into a cake tank 3. Is supplied to the centrifugal thin-film dryer 5 by the cake pump 4 to dry and solidify the distillation residue solids. The cake powder is taken out from the bottom of the centrifugal thin film dryer 5. The vapor evaporated by the centrifugal thin film dryer 5 is led to the heater 6 to heat the filtrate part sent by the filtrate pump 7.
The heated filtrate is introduced into the depressurized flash tank 8 and a part thereof is evaporated. The non-evaporated filtrate is repeatedly sent to the heater 6 by the circulation pump 9 and repeatedly evaporated in the flash tank 8 to be concentrated. The concentrate is returned to the cake tank 3 by the concentrate pump 10, mixed with the cake part, and sent to the centrifugal thin film dryer 5 by the cake pump 4. The vapor evaporated in the flash tank 8 is condensed in the condenser 11, and any non-condensed gas is exhausted by the vacuum pump 12. The condensate is received by the condensate tank 13, extracted from the vacuum by the first condensate pump 14, and supplied to an intermediate portion of the rectification column 16. On the other hand, the vapor condensate used for heating in the heater 6 is also supplied to the intermediate part of the rectification column 16 by the second condensate pump 15. In the rectification column 16, the steam blown into the bottom moves the low-boiling alcohol to the column top side in a manner to be expelled from the column bottom side. , Condensed in the top condenser 17, passed through the distilling tank 18,
Refluxed to the top of column 6. As the alcohol-rich liquid is refluxed, the concentration of alcohol at the top of the column becomes higher and higher. A part of the distillate that has reached the target alcohol concentration is withdrawn and recovered as crude alcohol. On the other hand, the bottoms discharged from the bottom of the rectification column 16 have almost no organic matter having a lower boiling point than water, and the BOD is greatly reduced. However, since the organic matter having a high boiling point is contained, the BOD is further removed by an aerobic water treatment apparatus. Process to lower.

The condensate of the steam obtained by evaporating the waste liquid containing the solid content of the distilled lees after the distillation of wheat shochu by the centrifugal thin film dryer 5 is BOD
Was 21,000 ppm, and the ethyl alcohol concentration was 0.7% by weight, but the BOD of the bottom bottom liquid was reduced to 3,500 ppm by the rectification column 16. By the way, 1500 cc of the condensate at the inlet of the rectification tower 16 was treated to obtain 28 cc of a distillate of 37.4% by weight of ethyl alcohol,
The distillate contained many other organic substances.

Embodiment 2 FIG. 4 shows a specific example of FIG. 2 and will be described in detail below.

The waste liquid containing the solid content of the distilled cake after alcohol distillation in alcohol brewing is separated by a centrifugal separator 1 into a filtrate tank 2 and a cake part mainly composed of solids into a cake tank 3. Is incinerated by the cake pump 4 by the incinerator 19. The flue gas from the incinerator 19 is heated by the heat exchanger 20 to heat the filtrate sent by the filtrate pump 7 and discharged. The heated filtrate part is the evaporation tank 2
It is introduced into 1 and a part evaporates. The non-evaporated filtrate is repeatedly sent to the heat exchanger 20 by the circulation pump 9 and concentrated by repeating evaporation in the evaporation tank 21. Concentrate is concentrate pump 1
Due to 0, it is returned to the cake tank 3 and mixed with the cake part and sent to the incinerator 19 by the cake pump 4. The vapor evaporated in the evaporation tank 21 is supplied to an intermediate portion of the rectification tower 22. As the vapor goes to the top of the rectification tower 22, the alcohol concentration of the low-boiling substances increases, and alcohol and the like exit from the top of the rectification tower 22 as steam together with moisture, and are condensed in the top condenser 17 and the distillation tank The mixture is returned to the top of the rectification column 22 via 18. As the alcohol-rich liquid is refluxed, the concentration of alcohol at the top of the column becomes higher and higher. A part of the distillate that has reached the target alcohol concentration is withdrawn and recovered as crude alcohol. On the other hand, the liquid side is
With the steam blown into the bottom of the tower as it goes to the bottom of the tower, it moves to the bottom of the tower in such a way that low-boiling substances are expelled,
The bottoms discharged from the bottom of the rectification tower 22 have almost no organic matter having a lower boiling point than water, and the BOD is greatly reduced. However, since an organic substance having a high boiling point is contained, it is treated by an aerobic water treatment apparatus to further reduce the BOD.

Embodiment 3 FIG. 5 shows an example in which the centrifugal separation shown in FIG. 4 is not required.

The waste liquid after alcohol distillation in alcohol brewing is sent directly to the heat exchanger 20 where it is exchanged with the combustion exhaust gas of the incinerator 19 and heated. The heated waste liquid is introduced into the evaporation tank 21 and a part thereof is evaporated. The non-evaporated filtrate is repeatedly sent to the heat exchanger 20 by the circulation pump 9 and concentrated by repeating evaporation in the evaporation tank 21. The concentrate is sent to the incinerator 19 by the concentrate pump 10 and incinerated. The combustion exhaust gas from the incinerator 19 exchanges heat with the waste liquid and the circulating liquid in the heat exchanger 20 and is discharged. After the evaporating tank 21, rectification is performed in the same manner as in FIG.

Embodiment 4 FIG. 6 shows a simplest embodiment of FIG.

The waste liquid containing the distilled solids after alcohol distillation in the alcohol brewing is supplied to the centrifugal thin film dryer 5 to dry the solids of the dried solids into powder. The cake powder is taken out from the bottom of the centrifugal thin film dryer 5. The vapor evaporated from the centrifugal thin film dryer 5 is supplied to an intermediate portion of the rectification tower 22. Thereafter, it is rectified in the same manner as in FIG. 4 of Example 2 to obtain a bottom liquid having a low BOD.

[0023]

According to the present invention, since the BOD is physically reduced instead of being treated by a microorganism, troublesome management of the microorganism is not required, and a stable BOD reduction can be immediately performed at any time. There is a volatile component among the components causing the BOD, and in particular, the waste liquid after alcohol distillation in alcohol brewing contains a little but less than 0.8% by weight of ethyl alcohol and the like. By evaporating and separating this ethyl alcohol together with water, other volatile organic substances are also evaporated by an amount corresponding to the vapor pressure, and as a result, the BOD is reduced by more than the ethyl alcohol. Ethyl alcohol containing water and other organic matter obtained from the top can be recovered.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of a waste liquid treatment apparatus according to the present invention.

FIG. 2 is a configuration diagram showing another embodiment of the waste liquid treatment apparatus according to the present invention.

FIG. 3 is a configuration diagram showing another embodiment of the waste liquid treatment apparatus according to the present invention.

FIG. 4 is a configuration diagram showing another embodiment of the waste liquid treatment apparatus according to the present invention.

FIG. 5 is a configuration diagram showing another embodiment of the waste liquid treatment apparatus according to the present invention.

FIG. 6 is a configuration diagram showing another embodiment of the waste liquid treatment apparatus according to the present invention.

FIG. 7 is a configuration diagram illustrating an example of a conventional waste liquid treatment apparatus.

[Explanation of symbols]

1 ... centrifuge, 2 ... filtrate tank, 3 ... cake tank,
4: Cake pump, 5: Centrifugal thin film dryer, 6: Heater,
7: Filtrate pump, 8: Flash tank, 9: Circulation pump, 10: Concentrate return pump, 11: Condenser, 1
2 vacuum pump, 13 condensate tank, 14 condensate pump, 15 second condensate pump, 16, 22 rectification tower,
17 ... Tower condenser, 18 ... Distillate tank, 19 ...
Incinerator, 20: heat exchanger, 21: evaporation tank.

Continuing on the front page (72) Inventor Kentaro Yoneyama 794, Higashi-Toyoi, Kazamatsu, Kudamatsu, Yamaguchi Prefecture Inside the Hitachi Kasado Engineering Co., Ltd. Inside the factory

Claims (5)

[Claims] 1. A waste liquid containing an organic substance having a boiling point lower than that of water is rectified by a rectification column, and an organic substance having a boiling point lower than that of water is extracted as a distillate from the top of the column as a distillate while containing water. A waste liquid treatment method comprising obtaining a bottom liquid having a low oxygen demand. 2. A method according to claim 1, wherein the vapor generated by concentrating or drying the waste liquid containing an organic substance having a boiling point lower than that of water is supplied directly to a rectification tower to rectify the organic substance, and the organic substance having a boiling point lower than that of water is distilled out. A waste liquid treatment method comprising extracting a liquid from the top of the tower as a liquid and obtaining a bottom liquid having a low biological oxygen demand from the bottom of the tower. 3. A treatment method involving the generation of steam, such as evaporation or drying of either the filtrate or the solids side after solids separation, such as filtration or centrifugation, directly or by filtration or centrifugation. Steam is supplied directly or as a condensate to the rectification tower, and organic substances having a lower boiling point than water are extracted as distillate from the top of the tower while containing water. A method for treating an alcohol distillation residue waste liquid, comprising obtaining a liquid. 4. A rectification column for rectifying a waste liquid containing an organic substance having a boiling point lower than that of water, and a withdrawal for extracting an organic substance having a boiling point lower than that of water as a distillate from the top of the rectification tower while containing water. A waste liquid treatment apparatus comprising: a discharge means; and a liquid collecting means for obtaining a bottom liquid having a low biological oxygen demand from the bottom of the tower. 5. A steam generating means for generating evaporated vapor by concentrating or drying a waste liquid containing an organic substance having a boiling point lower than that of water, a rectifying tower to which the generated steam is directly supplied, and a rectifying tower. Extracting means for rectifying the directly supplied steam and extracting an organic substance having a boiling point lower than that of water from the top of the column as a distillate in a state containing water, and a biological oxygen demand from the bottom of the rectification column. A waste liquid treatment apparatus comprising a liquid collecting means for obtaining a small amount of bottom liquid.