JP2753852B2 - Sewage treatment method and apparatus using hollow fiber membrane - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a sewage treatment apparatus using a hollow fiber membrane, and more particularly, to a bioreactor (biological reaction treatment tank) and a solid-liquid using a hollow fiber membrane. The present invention relates to a sewage treatment method and apparatus combined with a separation tank.

[Prior Art] Conventionally, solid-liquid separation in this type of sewage treatment uses a flat membrane or a tubular membrane.

However, in the above-mentioned conventional solid-liquid separation, it is necessary to apply a turbulent flow to the mixed solution in order to prevent the occurrence of concentration polarization on the membrane surface and the adhesion of the mud gel layer, and therefore, the required power becomes large. There was a problem.

There are also problems such as the necessity of ball washing to remove and remove the gel layer attached to the film surface, and the difficulty in controlling the permeation flow rate.

[Problems to be Solved by the Invention] The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to effectively prevent clogging of a film due to a generated gel layer. To provide a method and an apparatus for treating sewage with a hollow fiber membrane, which can easily control the permeation flow rate of the membrane to give flexibility to the treatment capacity, and furthermore, can make the apparatus compact. It is.

[Means for Solving the Problems] The method for treating sewage using a hollow fiber membrane of the present invention is a method for freely filling a bundle of hollow fiber membranes into a mixed solution containing biological flocks subjected to a biological reaction by a bioreactor having a variable water level. And
In the method of intermittently sucking the inside of the hollow fiber membrane having a closed lower end to separate the mixed solution into a permeate and a concentrate and returning the concentrate to the bioreactor, the water level fluctuation of the bioreactor The suction / pause time of the intermittent suction is changed to control the permeation flow rate. Further, a sewage treatment apparatus using a hollow fiber membrane of the present invention includes a bioreactor for performing a biological reaction treatment on organic sewage whose water level fluctuates, a solid-liquid separation tank for introducing a mixed solution containing biological floc from the bioreactor, Means for intermittently sucking a bundle of a large number of hollow fiber membranes suspended freely and suspended at the lower end in a state of being freely suspended in a solid-liquid separation tank, and a permeated liquid inside each hollow fiber membrane A timer for setting the suction time of the intermittent suction means, and means for returning the concentrated liquid in the solid-liquid separation tank to the bioreactor. Furthermore, a bioreactor for performing a biological reaction treatment on the organic wastewater whose water level fluctuates, a bundle of a large number of hollow fiber membranes suspended freely and freely hanging in the bioreactor, and an inside of the hollow fiber membrane And a timer for setting a suction time of the intermittent suction means.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a sand removing device, and reference numeral 2 denotes a screen, which removes solid matter such as earth and sand mixed in a stock solution.

3 is a variable capacity type bioreactor (biological reaction processing tank)
The stock solution flows through the inflow pipe 4. In this embodiment, the water is supplied by natural flow, but it may be supplied by a pump (not shown) as appropriate.

The influx amount of the undiluted solution changes with time, so that the mixed liquid containing the biological flocs in the bioreactor 3, that is, the activated sludge mixed liquid 5 fluctuates up and down (HWL, LWL). I have.

An air diffuser 6 is provided at the bottom of the bioreactor 3 so that air supplied from an aeration blower 7 is diffused into the mixture 5.

Reference numeral 8 denotes an outflow pipe, which discharges the mixed liquid from the bottom of the bioreactor 3 by a pump 9.

The mixed liquid discharged from the outflow pipe 8 is sent to a solid-liquid separation tank 12 on the way, from which solids are removed by a screen 10 and a sand removing device 11.

A large number of hollow fiber membranes 13 are suspended in the solid-liquid separation tank 12 in a state of freely hanging in a bundle. Therefore, the hollow fiber membrane 13 can freely float in the solid-liquid separation tank 12 while freely spreading in the tank 12 by the water flow flowing down in the solid-liquid separation tank 12.

The hollow fiber membrane 13 is, for example, made of a synthetic resin such as polyethylene having a myriad of fine holes of about 0.1 μm and having a diameter of 0.1 mm.
It is a thread-like hollow tube of about 8 mm. The hollow fiber membrane 13 is not limited to this, and any hollow fiber membrane that has been used or developed so far may be used.

The upper end of the bundle of the hollow fiber membranes 13 is fixed to the suction chamber 14 in an open state. On the other hand, the lower end of the hollow fiber membrane 13 is closed. Incidentally, the hollow fiber membrane 13 may be hung in a loop shape, and both ends thereof may be fixed in the suction chamber 14. Further, the hollow fiber membrane 13 may be oriented in any direction such as horizontal or oblique.

A return pipe 15 returns the concentrated liquid in the solid-liquid separation tank 12 to the bioreactor 3.

Reference numeral 16 denotes a suction device, which sucks the inside of the suction chamber 14, that is, the hollow fiber membrane 13 to a low pressure state, thereby removing solids, microorganisms, viruses, and the like from the mixed liquid in the solid-liquid separation tank 12. Only the removed liquid is allowed to permeate into the hollow fiber membrane 13 to separate solid and liquid.

Reference numeral 17 denotes an intermittent timer which changes the suction time and the pause time by appropriately setting the operation time of the suction device 16.

 Next, a processing method using the above-described embodiment apparatus will be described.

First, a solid such as sand is separated from the undiluted solution of the organic sewage by the sand removing device 1 and the screen 2 and introduced into the bioreactor 3 from the inflow pipe 4. When the undiluted solution contains oil, such as kitchen wastewater, the oil is separated before the bioreactor 3
To be introduced.

The organic sewage introduced into the bioreactor 3 becomes an activated sludge mixture 5. The water level fluctuates up and down in the bioreactor 3 according to a change in the inflow from the inflow pipe 4 and the outflow from the outflow pipe 8.

An air diffuser 6 is disposed at the bottom of the bioreactor 3 and air is supplied from an aeration blower 7, so that organic matter in the sewage flowing into the bioreactor 3 is adsorbed by the aerobic microbial floc and further oxidized. Decomposed and purified.

The treated water containing the activated sludge is sent from a discharge pipe 8 to a solid-liquid separation tank 12 by a pump 9.

The sewage flowing into the solid-liquid separation tank 12 is sucked into the suction chamber 14 through the fine holes of the hollow fiber membrane 13, and the permeated liquid is sent to the water pipe
Extracted from 18 as treated water.

The concentrate not sucked by the hollow fiber membrane 13 is returned to the bioreactor 3 through the return pipe 15.

The suction device 16 is operated intermittently by an intermittent timer 17 to control the permeation flow rate. still,
The intermittent timer 17 may be controlled by a computer.

FIG. 2 shows another embodiment of the present invention.
13 is filled in the bioreactor 3 to make the whole apparatus compact.

In each of the above embodiments, the processing in the aerobic bioreactor has been described, but the present invention is not limited to this, and may be an anaerobic bioreactor. In this case, the bioreactor needs to be capped, trapped and heated.

[Effect of the Invention] 1. By repeatedly sucking and stopping the inside of the hollow fiber membrane, the gel layer is prevented from adhering to the surface of the hollow fiber membrane and becoming compacted. Is peeled off,
The operation can be efficiently continued for a long time.
Since the hollow fiber membrane moves freely while freely expanding, the state of contact with the liquid is constantly changed even in the absence of the stirring flow, so that the filtration efficiency is good.

2. The flow rate can be controlled by appropriately changing the suction time and pause time in relation to fluctuations in the water level of the biological reaction processing tank, so that it is possible to flexibly cope with changes in the facility scale and throughput. , Energy saving.

3. The present invention can be applied to sewage treatment facilities, industrial wastewater treatment facilities, wastewater reuse facilities, and modifications of existing treatment facilities.

[Brief description of the drawings]

FIG. 1 is a flowchart of a sewage treatment system showing one embodiment of the present invention, and FIG. 2 is a flowchart showing another embodiment. DESCRIPTION OF SYMBOLS 1 ... Sand removal apparatus, 2 ... Screen, 3 ... Bioreactor, 4 ... Inflow pipe, 5 ... Activated sludge mixture, 6 ... Aeration pipe, 7 ... Aeration blower, 8 ... Outflow pipe, 9 ... pump, 10 ... screen, 11 ... sand removal device, 12 ... solid-liquid separation tank, 13 ... hollow fiber membrane, 14 ... suction chamber, 15 ... return pipe,
16 ... suction device, 17 ... intermittent timer, 18 ... water pipe.

Claims (3)

(57) [Claims] 1. A bundle of hollow fiber membranes is freely filled with a mixture containing biological flocks subjected to a biological reaction treatment by a bioreactor having a varying water level, and the inside of the hollow fiber membranes whose lower ends are closed is intermittently filled. In which the mixture is separated into a permeate and a concentrate, and the concentrate is returned to the bioreactor. In the method, the suction / pause time of the intermittent suction is changed in relation to the water level fluctuation of the bioreactor. And controlling the permeation flow rate by using a hollow fiber membrane. 2. A bioreactor for performing a biological reaction treatment on an organic wastewater having a fluctuating water level, a solid-liquid separation tank for introducing a mixed liquid containing biological floc from the bioreactor, and a free-falling solid liquid in the solid-liquid separation tank. Bundle of a large number of hollow fiber membranes suspended freely and suspended at the lower end, means for intermittently sucking the permeated liquid inside each hollow fiber membrane, and suction by the intermittent suction means A sewage treatment apparatus using a hollow fiber membrane, comprising: a timer for setting a time; and means for returning the concentrated liquid in the solid-liquid separation tank to the bioreactor. 3. A bioreactor for biologically treating an organic sewage having a fluctuating water level, a bundle of a large number of hollow fiber membranes suspended freely in the bioreactor while freely floating, and the hollow fiber A sewage treatment apparatus using a hollow fiber membrane, comprising: means for intermittently sucking a permeated liquid inside the membrane; and a timer for setting a suction time of the intermittent suction means.