JPS61287496A - Treatment of liquid containing organic matter - Google Patents

Abstract

PURPOSE:To advantageously utilize the residual pressure which has been discharged heretofore and to increase the reaction rate as much as possible by returning a pressurized concd. liq. on the concd. liq. side of a membrane separator to a pressurized aerobic vessel and carrying out the reaction in the aerobic vessel under pressure. CONSTITUTION:An normal-pressure aerobic vessel 1 and a membrane separator 3 are arranged in the order described, a liq. contg. org. matter is introduced into the vessel 1 and allowed to react and the treated liq. discharged form the vessel 1 is introduced into the separator 3 wherein low-molecular valuable materials are separated by the membrane into the permeated liq. side. In the method, a pressurized aerobic vessel 15 is provided on the upstream side of the vessel 1 and bacteria are retained at high concn. in the vessel 15. The pressurized concd. liq. on the concd. liq. side of the separator 3 is returned to the vessel 15 and the reaction in the vessel 15 is carried out under pressure. Namely, the residual pressure which has been discharged heretofore without being reutilized can be advantageously utilized, the reaction rate for the treatment can be increased as much as possible and the raw material can be converted into valuable materials with high precision.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for treating a liquid containing organic substances, and in particular, the present invention relates to a method for treating a liquid containing organic substances, and more specifically, for treating a liquid containing other valuable substances, such as a liquid containing glucose after saccharifying pulp waste liquid. The present invention relates to a method for treating liquids containing convertible organic substrates.

[Prior Art 1] FIG. 2 is a flow explanatory diagram showing a typical conventional processing system A. In said system A, the raw material to be treated is conducted via line 5 into reaction bed l. An example of the raw material is a glucose-containing liquid obtained by saccharifying cellulose contained in pulp waste liquid, and the case where the glucose-containing liquid is used as a raw material will be explained below. Since air is supplied to the reaction tank l via the pipe 12 and the condition is aerobic, the raw material introduced into the reaction layer l is
Aerobic fermentation is carried out by bacterial cells such as yeast supported on a carrier (not shown) inside, and ethanol and the like are produced. The ethanol-containing liquid (containing unreacted glucose, etc.) from the reaction layer 1 is introduced into the water tank 2 through the pipe 6. The water tank 2 contains I
Af, water whose flow rate is adjusted by the adjustment valve 7 is supplied and mixed with the ethanol-containing liquid. Therefore, the ethanol-containing liquid is diluted with water in the water tank 2, and the membrane separator 3
In this process, valuable substances such as ethanol are easily separated by membrane. A pressurized ethanol-containing liquid is drawn out from the water tank 2 by a high-pressure pump 8 and introduced into the concentrate side of the membrane separator 3 via a pipe 9. In the membrane separation device 3, low molecular weight substances such as ethanol are membrane-separated as a permeated liquid, and the permeated liquid is stored in a storage tank 4 via a pipe line 10.

Further, in the membrane separation device 3, the pressurized concentrate on the concentrate side is taken out under atmospheric pressure via the discharge pipe 11, and is disposed of or subjected to other appropriate disposal with the residual pressure released.

[Problem to be Solved by the Invention 1] In the membrane separation technology described in Part 2, the liquid to be treated in the water tank 2 is introduced into the membrane separation device 3 in a pressurized state by the high-pressure pump 8. Currently, concentrated liquids with residual pressure are discarded without utilizing the residual pressure.

Membrane separation technology has conventionally been classified into reverse osmosis membrane method, ultrafiltration method, etc. for convenience, but reverse osmosis membrane method in particular aims to separate low-molecular solutes from high-molecular substances, salts, etc. , requiring significantly high pressure. The supply pressure by the high-pressure pump 8 to the membrane separation device 3 varies depending on the quality of the supplied water, the properties of the membrane, the size of the device, etc.;
It is in the range of ~50 kg/cm2, and the residual pressure on the concentrate side is about 10-20 kg/cm2, which is considered to be energy with high utility value.

On the other hand, regarding reaction tank 1, floating methods and fixed bed methods have long been known as methods for retaining bacterial cells in reaction tank 1, but the purpose is to further increase the frequency of contact with bacterial cells. A fluidized bed method, an expansion method, etc. have been developed, and the fluidized bed method, expansion method, etc. are recommended in order for the reaction to proceed quickly in the reaction tank. It is a well-known fact that in an aerobic reaction, the higher the bacterial cell concentration, the more oxygen must be supplied in proportion to the bacterial cell concentration. As a means of increasing the oxygen supply capacity into the reaction tank by -IZ, there is a method of keeping the inside of the reaction tank under pressure and increasing the saturated dissolved oxygen concentration.
This makes it possible to increase the amount of dissolved oxygen. Therefore, the present inventors conducted research to provide a means for effectively realizing such a means, and completed the present invention.

That is, the present invention effectively utilizes residual pressure, which was conventionally discarded without being utilized, as the above-mentioned pressurizing means to produce an organic substance-containing liquid that increases the reaction rate for treatment as much as possible. Its purpose is to provide a method for processing.

[Means for Solving the Problems] In the present invention, a normal pressure aerobic tank and a membrane separation device are arranged in the above-mentioned order, and a liquid containing an organic substance is guided to the normal pressure aerobic tank and reacted. In the method for membrane-separating low-molecular valuables to the permeate side by introducing the reaction treated liquid taken out from the reaction tank under pressure to the membrane separation device described in -1- the normal pressure aerobic tank. A pressurized aerobic tank is provided on the upstream side of the pressurized aerobic tank to maintain a high concentration of bacterial cells in the pressurized aerobic tank. The gist is that the reaction in the pressurized aerobic tank is carried out under pressure by returning the gas to the aerobic tank.

[Function] - As mentioned above, as a means to increase the oxygen supply capacity into the reaction tank, a configuration is adopted in which the amount of dissolved oxygen is increased by keeping the inside of the reaction layer under pressure and increasing the saturated dissolved oxygen concentration. are doing. That is, as shown in equation (1) below, the oxygen transfer rate δC/δt depends on the saturated dissolved oxygen concentration C8, and when the inside of the reaction tank is pressurized, the saturated dissolved oxygen concentration C
By increasing s, the oxygen transfer rate δC/δt, and therefore the amount of dissolved oxygen, can be increased.

δC/δt=K ・(S/V)(Cs-G)-r
-(1) where K is the mass transfer coefficient, S is the gas-liquid interfacial area,
(2) represents the liquid volume, C represents the dissolved oxygen concentration, and r represents the oxygen consumption rate of the bacterial cells.

In realizing the second guideline, the present inventors have completed the present invention based on the viewpoint of effectively utilizing the residual pressure on the concentrated liquid side, which has not been utilized in the past.

According to the present invention, by adopting the configuration as described, effective utilization of residual pressure is achieved, and it becomes possible to increase the reaction rate in the pressurized aerobic tank as much as possible. Ta.

Hereinafter, the present invention will be explained in more detail with reference to FIG.

[Example] FIG. 1 is a flow explanatory diagram showing one embodiment of the method of the present invention. The basic configuration of the system B of the present invention is the same as that of the conventional system A shown in FIG. 2, and corresponding parts are given the same reference numerals to avoid redundant explanation. In the system B of the present invention, a pressurized aerobic tank 15 is provided upstream of the reaction tank 1. A return path 16 is connected to the pressurized aerobic tank 15 for returning the pressurized liquid from the concentrated liquid side of the membrane separation device 3 . The pressurized concentrate on the concentrate side of the membrane separation device 3 is returned to the pressurized aerobic tank 15 via the return path 16 . Since the return line 16 is connected to a pipe line 20 for feeding compressed air from the compressor 17 under pressure, the compressed air is supplied into the pressurized aerobic tank 15 together with the pressurized concentrate on the concentrate side. A main valve 18 and an auxiliary valve 19 are interposed in the pipe line 20, and the flow rate and pressure of compressed air supplied from the compressor 17 to the pressurized aerobic tank 15 are adjusted by the main valve 18 and the auxiliary valve 19. .

The pressure of the pressurized liquid supplied from the concentrate side of the membrane separator 3 to the return path 16 is, for example, 10 to 20 kg7cm2.

By supplying the pressurized liquid having such high pressure to the pressurized aerobic tank 15 together with compressed air from the compressor 17, the inside of the pressurized aerobic tank 15 is brought into an aerobic and pressurized state.

A pipe line 24 is provided at the top of the pressurized aerobic tank 15,
The pipe line 24 is connected to the bottom of the reaction tank I. Conduit 2
A control valve 25 is interposed in 4, and the pressure inside the pressurized aerobic tank 15 is adjusted by controlling the opening degree of the control valve 25. The pressure inside the pressurized aerobic tank 15 is, for example, 5 to 20
It is maintained at a high pressure of kg/cm2. Pressurized aerobic tank 15
A pressure gauge 30 is provided, and the pressure inside the pressurized aerobic tank 15 can be visually checked using this pressure gauge 30. By pressurizing the inside of the pressurized aerobic tank 15 in this way, the saturated dissolved oxygen concentration inside the pressurized aerobic tank 15 can be increased, and the configuration of the pressurized aerobic tank 15 can be enlarged. It becomes possible to increase the concentration of bacterial cells without causing any problems.

The raw material to be treated according to the present system B is a glucose-containing liquid obtained by, for example, saccharifying cellulose in pulp waste liquid (acid hydrolysis, etc.) as described in -1-. The raw material is stored in a raw material tank 22, and is pumped through the pipe line 2 by a pump 31.
3 into the reaction tank 1. There is an exhaust pipe 3 in the reaction tank 1.
2 is provided, and the inside of the reaction tank 1 is maintained at approximately normal pressure. A liquid to be treated containing oxygen is supplied from the pressurized aerobic tank 15 to the reaction tank 1 via the pipe line 24, and the inside of the reaction tank 1 is made into an aerobic atmosphere. Furthermore, in order to further promote the reaction in the reaction tank 1, it is also effective to supply oxygen from the compressor 17. Therefore, the pipe line 20 may be branched to provide a pipe line as shown by an imaginary line 33, and the air from the compressor 17 may be supplied into the reaction tank 1 while adjusting the flow rate with the flow rate regulating valve 34.

Glucose is converted to ethanol by the action of bacterial cells in the reaction tank 1, and the glucose-containing liquid becomes an ethanol-containing liquid. However, since the inside of the reaction tank 1 is at normal pressure, the reaction does not always proceed quickly and a considerable amount of unreacted glucose remains. This residual glucose is removed from the membrane separator 3
The concentrate is supplied into the pressurized aerobic tank 15 via the return path 16. In the pressurized aerobic tank 15, bacterial cells are maintained at a high concentration and are in a pressurized state, so that unreacted glucose is efficiently converted to ethanol. The liquid to be treated in the pressurized aerobic tank 15 is returned to the reaction tank 1 again. In this way, the raw material is supplied to the reaction tank 1, and the liquid containing unreacted glucose in the reaction tank 1 is circulated to the pressurized aerobic tank 15, thereby increasing the reaction rate and converting the raw material into valuable materials with high precision. It is possible to convert it into objects.

In the above embodiment, a case was described in which a glucose-containing liquid after saccharifying a pulp waste liquid is converted into an ethanol-containing liquid, but according to the spirit of the present invention, it is not limited to the case where industrial wastewater such as pulp waste liquid is treated. It can also be suitably carried out when treating urban wastewater such as human waste.

- Also, in order to use the pressurized liquid on the concentrate side of the membrane separation device 3 for multiple purposes, a bypass pipe 26 is provided that branches from the return path 16, and the pressurized concentrate on the concentrate side is supplied to the water tank 2. You can do it like this. A flow rate regulating valve 27 is provided in the bypass pipe 26.
is interposed, and the flow rate of the pressurized liquid returned to the water tank 2 is adjusted by the flow rate adjustment valve 27. The bypass pipe 26 is
This is provided for the purpose of increasing the linear velocity on the membrane surface of the membrane separator 3 to prevent solid content from adhering to the membrane surface during the summer, and adjusts the hydric acid supplied from the water tank 2 to the membrane separator 3. By doing so, you will achieve the purpose listed in item 1-.

[Effect of the Invention 1] As described above, according to the present invention, it is possible to advantageously utilize the residual pressure that was conventionally discarded without being utilized, and to increase the reaction rate for treatment as much as possible. This has made it possible to convert raw materials into valuables with high precision.

[Brief explanation of the drawing]

FIG. 1 is a flow explanatory diagram showing an example of an embodiment of the present invention,
FIG. 2 is a flow explanatory diagram showing a conventional typical processing system A.

Claims (1)

[Claims] A normal pressure aerobic tank and a membrane separation device are arranged in the above described order, the liquid containing organic substances is led to the above normal pressure aerobic tank and reacted, and the reaction treated liquid taken out from the reaction tank is subjected to the above membrane separation. In a method of membrane-separating low-molecular-weight valuables to the permeate side by introducing them into a device under pressure, a pressurized aerobic tank is provided upstream of the normal-pressure aerobic tank, and in the pressurized aerobic tank, The bacterial cells are maintained at a high concentration, and the pressurized concentrate on the concentrate side of the membrane separation device is returned to the pressurized aerobic tank to carry out the reaction in the pressurized aerobic tank under pressure. A method for treating a liquid containing an organic substance, characterized by: