JPH11216343A - Waste liquid treating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a waste liquid treating device capable of preventing effectively clogging of a membrane module. SOLUTION: A power source 4 is connected to a case 3a and a membrane module 3 having a membrane 13 arranged in the case 3a. The membrane becomes electrically conductive, the electrically conductive membrane 13 becomes a cathode by a voltage from the power source 4, and the electrically conductive part in the case 4 becomes an anode. A solid or the like stuck to the membrane 13 is charged with a negative electric charge, and separated from the membrane 13 by making the membrane cathodic to prevent clogging of the membrane 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wastewater treatment apparatus having a cross-flow type membrane module, and more particularly to a wastewater treatment apparatus capable of effectively removing deposits attached to a membrane of a membrane module.

[0002]

2. Description of the Related Art When membrane separation is applied to drainage treatment, the biggest problem is clogging of membrane (fouling).
It is. The rate of decrease in the membrane permeation flow rate can be suppressed,
A cross-flow type membrane module that can periodically clean the membrane such as reverse washing and remove solids deposited on the membrane surface at the flow rate of the water to be treated is used to prevent membrane clogging.

[0003]

However, clay particles such as kaolin, which is a main cause of membrane fouling,
Algae, humic substances and the like cannot be completely removed by a washing method such as back washing even in a cross-flow type membrane module, resulting in blockage of the membrane and reduction of the membrane permeation flow rate.

[0004] The present invention has been made in view of such a point, and it is an object of the present invention to provide a drainage treatment apparatus capable of effectively preventing membrane blockage of a cross-flow type membrane module.

[0005]

SUMMARY OF THE INVENTION The present invention comprises a case having an electrically conductive portion inside and connected to an inflow line, a return line, and an outflow line, and an electrically conductive film disposed in the case. A cross-flow type membrane module and a power supply for applying a voltage to the electrically conductive portion and the electrically conductive film such that the electrically conductive portion of the case is an anode and the electrically conductive film is a cathode, A drainage treatment apparatus characterized in that inflowing water to be treated is filtered by an electric conductive film, and a negatively charged substance attached to the electric conductive film is removed from the electric conductive film.

According to the present invention, a voltage is applied from a power supply, with the electrically conductive portion of the case as an anode and the electrically conductive film as a cathode. This makes it possible to effectively remove the negatively-charged deposit attached to the electrically conductive film from the electrically conductive film.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are views showing an embodiment of a drainage treatment apparatus according to the present invention.

[0008] As shown in FIG.
a, a cross-flow type membrane module 3 having a membrane 13 disposed in a case 3a, a power supply 4 for applying a voltage to the membrane module 3, and a control device 20 for controlling the power supply 4. I have.

Among them, the cross-flow type membrane module 3
Case 3a has an inflow line 2 having a circulation pump 2
The circulating tank 1 is connected to the circulating tank 1 via a line 1, and a return line 22 is connected between the case 3a and the circulating tank 1.

Further, the inflow line 21a and the circulation tank 1 are connected via a bypass line 23 having a bypass valve 7a, and drainage flows into the circulation tank 1 from an upstream side via a drainage line 8. It has become.

A backwash tank 5 is connected to the case 3a through an outflow line 24 having an outflow valve 7b, and a backwash pump 6 having a backwash pump 6 is provided between the backwash tank 5 and the outflow line 24. It is connected via line 25.

As shown in FIG. 1, a pressure gauge 11 is mounted on an inflow line 21 and flow meters 9 and 10 are mounted on a return line 22 and an outflow line 24, respectively.

Further, a pressure gauge 11, flow meters 9, 10,
The circulation pump 2, the backwash pump 6, the bypass valve 7a, the outflow valve 7b, and the backwash valve 7c are each connected to the control device 20.

Next, the internal structure of the membrane module 3 will be described in detail with reference to FIG. As shown in FIG. 3, a membrane 13 supported by a support 14 is provided in a case 3a of the membrane module 3.
And an electrically conductive portion 15. Among these, the film 13 is electrically conductive, and a voltage is applied to the electrically conductive film 13 and the electrically conductive portion 15 from the power supply 4 so that the electrically conductive film 13 becomes a cathode and the electrically conductive portion 15 becomes an anode. Applied. In addition, the electrically conductive film 13 and the electrically conductive portion 15 are both made of a material that is less eluted by an electrode reaction.

Next, the operation of the embodiment having the above-described configuration will be described.

First, as shown in FIG. 1, drainage (water to be treated) flows into the circulation tank 1 through a drainage line 8, and the circulation tank 1
The effluent in the inflow line 21
Flows into the case 3a of the cross-flow type membrane module 3 from. Part of the drainage in the case 3 a of the membrane module 3 is filtered through the membrane 13, flows into the backwash tank 5 through the outflow line 24, and then flows out of the treated water line 28 as treated water. On the other hand, the remaining drainage returns to the circulation tank 1 via the return line 22. Then, as the drainage passes, the membrane 1
Solids, suspensions and the like adhere to 3.

During this time, the flow meters 9 and 10 and the pressure gauge 11
Is input to the control device 20 and the inflow line 21
Pressure, return line 22 flow rate and outlet line 24
The circulation pump 2, the bypass valve 7a, and the outflow valve 7b are adjusted by the control device 20 so that the flow rate of the circulating fluid takes a predetermined value. At this time, the backwash pump 6 is stopped, and the backwash valve 7c is closed.

At the same time, the power supply 4 is driven and controlled by the control device 20, and the power supply 4 uses the electrically conductive film 13 as a cathode and the electrically conductive portion 15 as an anode with respect to the electrically conductive film 13 and the electrically conductive portion 15. A DC voltage is applied.

Generally, the electrically conductive film 13 of the membrane module 3
Since deposits such as solids and suspensions that adhere to the surface have a negative charge, by using the conductive film 13 as a cathode, these deposits are separated from the conductive film 13 and returned to the return line. It is returned to the circulation tank 1 via 22. The solids, suspended solids, and the like in the circulation tank 1 are then discharged outward from the discharge line 27 by opening the discharge valve 27a.

Next, when the membrane 13 is backwashed (backwashed), the circulating pump 2 is stopped by the control device 20 and the backwash pump 6 is driven, so that the treated water in the backwash tank 5 is treated by the membrane module. 3 in case 3a. Then, the electroconductive film 13 is backwashed with the treated water, and the backwash water after the backwash is discharged from the backwash discharge line 26 by opening the backwash valve 7c.

At the same time, the backwash pump 6 is controlled by the control device 20.
, The voltage of the power supply 4 rises above the normal voltage. Due to the rise in the voltage of the power supply 4, the backwash water in the case 3a is electrolyzed, and bubbles such as hydrogen gas are generated near the electrically conductive film 13. Due to the bubbles, the deposits attached to the surface and the inside of the electrically conductive film 13 can be effectively peeled off, and the backwashing effect of the film 13 can be enhanced.

Next, another embodiment of the present invention will be described with reference to FIG. In the embodiment shown in FIG. 3, the conductivity meter 12 for measuring the conductivity of the drainage is attached to the return line 22, and the conductivity from the conductivity meter 12 is sent to the control device 20. The rest is substantially the same as the embodiment shown in FIGS. 1 and 2.

In FIG. 3, the same parts as those of the embodiment shown in FIGS. 1 and 2 are denoted by the same reference numerals, and detailed description is omitted.

In FIG. 3, the conductivity of the water to be treated is measured by the conductivity meter 12, and based on this conductivity, the voltage applied to the power supply 4,
Controls the DC current flowing through the inside. Thereby, electrolysis of the drainage can be prevented, and deterioration of the electrically conductive film 13 due to an electrode reaction can be suppressed.

That is, when the conductivity of the drainage liquid is high,
When a high voltage is applied to the membrane module 3 from the power supply 4, an electrode reaction between the electroconductive film (cathode) 13 and the electroconductive portion (anode) 15 causes the electroconductive film 13 and the electroconductive portion 15 to be decomposed. Alternatively, the rate of elution increases. Further, when the conductivity of the drainage liquid is high, the pores of the membrane 13 are closed by the bubbles due to bubbles generated by electrolysis of the drainage liquid, that is, hydrogen gas generated from the surface of the electrically conductive film 13 which is a cathode. In some cases, the membrane permeation flow rate may decrease.

On the other hand, according to the present embodiment, when the conductivity of the drainage is high, the voltage applied from the power source 4 is reduced to prevent the drainage from being electrolyzed and to reduce the electric conductivity. The deterioration of the conductive film 13 due to the electrode reaction can be suppressed.

[0027]

As described above, according to the present invention, it is possible to effectively remove, from the electroconductive film, the load adhering to the electroconductive film of the membrane module. Therefore, clogging of the film can be prevented, and a decrease in the transmittance of the film can be prevented.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an embodiment of a drainage treatment apparatus according to the present invention.

FIG. 2 is a detailed view showing a membrane module of the drainage treatment device.

FIG. 3 is a schematic diagram showing another embodiment of the drainage treatment device.

[Explanation of symbols]

 3 Membrane Module 3a Case 4 Power Supply 12 Conductivity Meter 13 Electrically Conductive Membrane 15 Electrically Conductive Part 20 Controller 21 Inflow Line 22 Return Line 23 Bypass Line 24 Outflow Line 25 Backwash Line

Claims (3)

[Claims] 1. A cross-flow type membrane module comprising: a case having an electrically conductive portion inside and connected to an inflow line, a return line, and an outflow line; and an electrically conductive membrane disposed in the case. A power supply for applying a voltage to the electrically conductive portion and the electrically conductive film so that the electrically conductive portion of the case serves as an anode and the electrical conductive film as a cathode, and the water to be treated flowing into the case is electrically conducted. A wastewater treatment device, wherein the wastewater is filtered through a conductive membrane, and the negatively charged substances attached to the conductive membrane are removed from the conductive membrane. 2. A backwashing device is connected to the case, and a power supply is connected to a control device for controlling a power supply so that a higher voltage is applied when the backwashing device is activated than during normal filtration. The drainage treatment device according to claim 1. 3. The inflow line is connected to a conductivity meter for measuring the conductivity of the water to be treated, and the power supply is connected to a control device for controlling the power supply based on the measured value from the conductivity meter. The drainage treatment device according to claim 1, wherein: