JPH06292900A - Waste water treating device using ultrafilter membrane - Google Patents

Abstract

PURPOSE:To decrease the frequency of membrane washing by providing the circulation circuit which returns the separated concentrated liq. with a ultrafilter membrane to a circulation tank, the return circuit which returns some of the concentrated liq. to a reaction tank and the culture circuit which returns some of the concentrated liq. to the reaction tank after introducing to the culture tank and reactivating the microorganisms in the concentrated liq. CONSTITUTION:This device is provided with the reaction tank 1 where the microorganismic treatment of waste water is executed, the circulation tank 2 which is formed integrally or in another body and the ultrafilter membrane 3 which separates the suspension after reaction into a membrane-permeated water and the concentrated liq. by using a pressure as a driving force. The circulation circuit 4 which returns the separated concentrated liq. with the ultrafilter membrane 3 to the circulation tank 2, the return circuit 5 which returns some of the concentrated liq. to the reaction tank 1 through or not through the circulation circuit 4 and the culture circuit 7 which returns some of the concentrated liq. separated with the ultrafilter membrane 3 to the reaction tank 1 after introducing to the culture tank 6 and reactivating the microorganisms in the concentrated liq. are also provided. In such a manner, the frequency of membrane washing is decreased and the lifetime of the membrane is prolonged.

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 using an ultrafiltration membrane, and more specifically, it can stabilize a microbial treatment reaction in a reaction tank and effectively exhibit solid-liquid separation performance by the membrane. The present invention relates to wastewater treatment equipment using an ultrafiltration membrane.

[0002]

BACKGROUND OF THE INVENTION Generally, when performing biological treatment of wastewater,
A gravity sedimentation type pond is used as a solid-liquid separation means. In biological treatment, the presence of cells that oxidize is essential, but these cells are treated under treatment conditions (such as concentration of wastewater, temperature,
There was a problem that it was sensitively affected by pH, etc., did not show a certain active state and settling property, sludge flowed out from the settling basin, and the cell concentration in the biological reaction tank could not be maintained.

For this reason, an ultrafiltration membrane using pressure as a driving force has been introduced in place of the gravity sedimentation type sedimentation basin (see, for example, JP-A-61-146397). In the conventional process of such membrane treatment, the waste water is received in a reaction tank, the suspension after the reaction is separated into a membrane permeated water and a concentrated liquid by an ultrafiltration membrane by using pressure as a driving force, and This is a process of returning a part of the separated concentrated liquid into the reaction tank.

However, the filtration performance of the membrane is affected by clogging of the filtration channel, clogging of the membrane filtration surface, and clogging of the membrane pores. Therefore, unlike simple filtration, the excellent performance cannot be obtained unless measures are taken from various aspects to prevent deterioration of the membrane treatment performance.

The cause of the clogging of the filtration channel can be solved by physically removing the residue in the drainage, but the cause of the clogging of the membrane filtration surface and the clogging of the membrane pores is appropriate. There is no solution and there are various problems.

That is, in a system in which a part of the concentrated liquid separated in the ultrafiltration membrane is returned to the reaction tank as in the conventional membrane treatment process, the solid sludge in the concentrated liquid is completely blocked by the membrane. , The blocked solid sludge is getting more and more concentrated. Considering only the concentration balance, it is sufficient to pull out the solid sludge in the reaction tank in fixed amounts, but the amount of pulling out is usually the multiplication sludge (the amount of organic matter converted to microbial sludge) and BOD (biological oxygen demand). ) And COD (chemical oxygen consumption) components in consideration of inorganic solid components.

However, the components of the waste water include BOD and COD components which are difficult to decompose by microorganisms. Such a hardly decomposable substance cannot be extracted as solid sludge in the reaction tank because it is not converted into microbial sludge, so that it is blocked by the membrane and remains in the membrane system.

Further, since the drainage does not always have a constant property, a drainage adjusting tank is usually provided to buffer the property variation, but in reality, the drainage adjusting tank is used in consideration of cost reduction. It may not be provided, or the capacity of the drainage adjustment tank may have to be reduced. In such a case, waste water whose properties have changed must be received in the reaction tank.

Due to such changes in drainage properties and accumulation of the above-mentioned hardly-decomposable substances, sludge in the reaction tank becomes a sol-gel state and the activity of microorganisms in the reaction tank is lost, resulting in clogging of the membrane filtration surface. There is a problem that the conventional membrane treatment process cannot deal with at all, such as the clogging of the membrane pores of the above and the cause of foaming outflow from the reaction tank.

As a result of conducting research to solve such a problem, the present inventor has found that there is a problem in the basic recognition of the conventional film processing process.

That is, the membrane conventionally used as a means for substituting the sedimentation tank is effective because it does not cause sludge to flow out from the sedimentation tank when used when the microbial activity or sedimentation property in the reaction tank is poor. Had the recognition of. In other words, he knew that if membranes were used, biological treatment would not have to be considered specially.

However, although the sludge did not flow out of the settling tank, a new problem of foaming outflow from the reaction tank occurred as described above.

Conventionally, the solution to the clogging of the membrane has been considered only from the viewpoint of how to clean the membrane or, when the cleaning effect is lost, to replace the membrane with a new one. It is a reality. More recently, there has been a controversy over whether cleaning frequency is high or low depending on the type of membrane (flat membrane, tubular membrane, spiral membrane, etc.).

The present inventor believes that the conventional recognition does not complete the membrane treatment process at all, and the idea is completely different from the conventional perception, that is, improvement of biological treatment does not make the membrane effectively function. As a result of further research, the reaction system in the reaction tank was always kept in a fixed direction by recovering the microbial activity in the reaction tank even if the drainage property changed or the above-mentioned persistent substances accumulated. This has led to the present invention by finding that as a result, the number of times the membrane is washed naturally decreases and the life of the membrane itself also increases as a result.

On the other hand, when treating sewage, human waste or the like by membrane treatment, the preceding step of the reaction tank, that is, the discharge source of the waste water, the raw water tank for storing the waste water, or the adjusting tank for buffering the change in the properties of the waste water There is a problem with the odor from the plant, and its solution is desired.

That is, the first object of the present invention is to constantly keep the reaction system in the reaction tank constant by recovering the microbial activity in the reaction tank even when the drainage property is changed or the hardly decomposable substance is accumulated. The purpose of the present invention is to provide a wastewater treatment apparatus using an ultrafiltration membrane in which the number of times of membrane cleaning naturally decreases and the life of the membrane itself increases as a result.

A second object of the present invention is to provide a wastewater treatment device using an ultrafiltration membrane which can solve the problem of odor from the previous step of the reaction tank when treating sewage, human waste and the like. Especially.

[0018]

That is, a wastewater treatment apparatus using an ultrafiltration membrane according to the present invention that achieves the above first object is a reaction tank for treating wastewater with a microorganism, integrated with the reaction tank or It has a circulation tank formed as a separate body and an ultrafiltration membrane for separating the suspension after the reaction into a membrane permeated water and a concentrated liquid by using a pressure as a driving force, and the concentration separated in the ultrafiltration membrane A circulation circuit for returning a liquid to the circulation tank, a return circuit for returning a part of the concentrated liquid into the reaction tank with or without the circulation circuit, and a concentrated liquid separated in the ultrafiltration membrane. And a culture circuit for guiding a part of the solution to reactivate the microorganisms in the concentrated solution substantially in the culture tank and then returning the microorganisms to the reaction tank.

Further, a wastewater treatment apparatus using an ultrafiltration membrane according to the present invention which achieves the above-mentioned first object, comprises a reaction tank for treating microorganisms in wastewater, and a circulation formed integrally with or separately from the reaction tank. It has a tank and an ultrafiltration membrane that separates the suspension after the reaction into membrane permeated water and a concentrated liquid by using a pressure as a driving force, and returns the concentrated liquid separated in the ultrafiltration membrane to the circulation tank. Circulation circuit, a return circuit for returning a part of the concentrated liquid separated in the ultrafiltration membrane to the reaction tank and the preceding step of the reaction tank with or without the circulation circuit, and the ultrafiltration. And a culture circuit for guiding a part of the concentrated liquid separated in the membrane to substantially reactivate the microorganism in the concentrated liquid and then returning the microorganism to the reaction tank.

Further, a wastewater treatment apparatus using an ultrafiltration membrane according to the present invention which achieves the above first and second objects is formed with a reaction tank for treating wastewater with a microorganism and an integrated or separate body from the reaction tank. And a ultrafiltration membrane that separates the suspension after the reaction into membrane permeated water and a concentrated liquid by using a pressure as a driving force, and the concentrated liquid separated in the ultrafiltration membrane is circulated as described above. A circulation circuit for returning to the tank, a return circuit for returning a part of the concentrated liquid separated in the ultrafiltration membrane into the reaction tank with or without the circulation circuit, and a separation in the ultrafiltration membrane A cake obtained by chemical-free dehydration of a portion of the concentrated solution obtained or a return circuit for returning the dried sludge obtained by low-temperature or sun drying the cake to the previous step of the reaction tank, and the concentrated solution A portion of the microorganisms in the concentrated liquid is substantially reactivated in the fermentor by guiding the part. And having a culture circuit for returning to the reaction vessel after.

[0021] As a preferred embodiment of the present invention, (1) in the above, the preceding step of the reaction tank for returning the concentrated liquid separated in the ultrafiltration membrane is at least a discharge source of waste water, and a raw water tank for storing the waste water. Or one of the adjusting tanks for buffering the change in the property of the wastewater, (2) a reactor tank is provided separately from the culture tank, and the humus and the activated state or unstable in the reactor tank In the reactor tank, the micro-organisms in the concentrated liquid introduced from the culture tank into the reactor tank are filled with a granular material made of a mixture containing at least an andesite or a substance having a rhyolitic composition. Having an auxiliary culture circuit for reactivating and then returning to the culture tank, (3) A reactor tank is provided in the culture tank, and the reactor tank is in an activated or unstable state with a humus. The granules composed of a mixture containing at least a substance having a mountain rock or rhyolite composition are filled, and the microorganisms in the concentrated liquid introduced from the culture tank to the reactor tank are reactivated in the reactor tank. (4) The culture tank is a reactor tank, and the humus and the andesite or rhyolite in an activated or unstable state are present in the reactor tank. Of the mixture containing at least a substance having the composition of 1., introducing a part of the concentrated liquid separated in the ultrafiltration membrane into the reactor tank, and introducing the microorganisms in the concentrated liquid into the reactor tank. (5) In the above, the reactor tank had an inlet for receiving the concentrate separated in the ultrafiltration membrane in the upper part and was reactivated in an intermediate position. A mixture comprising at least a main body having an outlet for taking out concentrated sludge containing bacterial groups, a humic substance in the main body, and a substance having an andesite or rhyolite composition in an activated or unstable state. That is, it has a filling part filled with the granular material, and an air diffuser below the filling part capable of supplying air to the filling part.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a wastewater treatment device using an ultrafiltration membrane according to the present invention will be described with reference to the drawings.

Embodiment 1 FIG. 1 is a block flow sheet showing an embodiment of the wastewater treatment equipment according to the present invention.

In FIG. 1, reference numeral 1 is a reaction tank for treating waste water with microorganisms. The reaction tank 1 is a tank in which an active microorganism is inhabited, and is preferably a soil facultative anaerobic bacterial group or a bacterial group in which a soil facultative anaerobic bacterium and a soil aerobic bacterium coexist (hereinafter, these Is referred to as "soil bacteria group".)
It is the tank that inhabited.

The soil-based bacterial group does not need to exist from the beginning of the treatment, and the soil-based bacterial group occupies the priority species because the reaction tank initially contains microorganisms other than the soil-based bacterial group. You can also get used to it. Moreover, you may be accustomed using the seed sludge of soil-borne bacteria group. The method for producing the seed sludge of the soil bacteria group can be performed using a lector described below.

The reaction tank is provided with an air diffuser capable of supplying air so that oxygen can be supplied to the microorganisms in the reaction tank. In addition, the air diffuser mixes and agitates the pollutants and microorganisms in the waste water in the reaction tank, and establishes an environment in which the microbial reaction is promoted well.

The reaction mechanism cannot be the same depending on the type of microorganism. In the case of treatment with active microorganisms mainly consisting of aerobic bacteria, the main reaction is oxidative decomposition due to the chemical reaction of soluble substances in wastewater.For example, in the case of fine sludge mainly composed of zooglare, if it can maintain its active state, The flocculating property is exhibited by the cohesive property of.

In the case of soil-borne bacteria, oxidative decomposition is not the main reaction, but binding, particle formation, aggregation, condensation, polymerization, etc. by a chemical reaction between metabolites of soil-borne bacteria and soluble substances in wastewater. Rapidly progresses to enlarging the fine sludge and promotes adsorption and absorption of soluble components by this sludge-like substance, that is, purification of wastewater by rapid progress of incorporation of soluble components and sludge formation. It is a reaction mechanism (see JP-A-59-166293).

According to the treatment using the metabolites of the soil-based bacteria group, it is possible to take in soluble hardly decomposable substances and to promote sludge formation, which may cause clogging of the membrane. Disappear.

In the present invention, the subject to be treated is not particularly limited, but examples thereof include sewage, human waste, pig house drainage, various factory drainage, domestic wastewater and the like.

Next, in FIG. 1, 2 is a circulation tank. The circulation tank 2 may be formed integrally with the reaction tank 1 or may be formed separately. The circulation tank 2 may also serve as the second reaction tank. Furthermore, in the present invention, it is essential to use an ultrafiltration membrane as the solid-liquid separation means after the reaction, but the circulation tank may have incomplete solid-liquid separation means. The incomplete solid-liquid separation means referred to here is, for example, a precipitation tank having a small capacity, and the ultrafiltration membrane, which will be described later, has a higher order (3
Next) It is not intended to function as a process. That is, when the sludge sent from the reaction tank to the circulation tank has a very good settling property, the sludge may be roughly removed before solid-liquid separation by the ultrafiltration membrane.

Reference numeral 3 is an ultrafiltration membrane for separating the suspension after the reaction into a membrane permeated water and a concentrated liquid by using a pressure as a driving force. The ultrafiltration membrane is used for solid-liquid separation depending on the molecular weight cutoff, and generally targets substances having a thickness of about 10 angstroms to 5 μm. Due to the difference in the membrane structure, etc., the membrane type is flat membrane,
It may be a tubular type, a hollow fiber or a spiral type, but a flat membrane is preferable from the viewpoint of convenience of handling the membrane, easiness of washing and the like.

A circulation circuit 4 serves to feed the suspension after the reaction from the circulation tank 2 to the ultrafiltration membrane 3 and to return the concentrated liquid after the membrane separation to the circulation tank 2.

Reference numeral 5 is a return circuit for returning the concentrated liquid after membrane separation to the reaction tank 1. The return amount in the return circuit 1 is preferably in the range of 100 to 200 vol% with respect to the drainage amount. A part of the circulating liquid in the circulation circuit 4 may be introduced into the return circuit 5.

6 is a culture tank for guiding a part of the concentrated liquid separated in the ultrafiltration membrane to reactivate microorganisms in the concentrated liquid, and 7 is after reactivating in the culture tank 6, It is a culture circuit for returning the reaction solution into the reaction tank 1. Reference numeral 8 is a reactor tank, and 9 is an auxiliary culture circuit that is reactivated in the reactor tank 8 and then returned to the culture tank 6.

In the present invention, "substantially reactivate in the culture tank" means that when the culture tank 6 also serves as the reactor tank 8, the reactor tank 8 may be reactivated, or the culture tank 6 may be reactivated. This means that the reactor tank 8 may be reactivated separately, or when the reactor tank 8 is provided in the culture tank 6.

When the reactor tank 8 is provided separately from the culture tank 6 or inside the culture tank 6, the culture tank 6 is further reactivated in the reactor tank 8 and then the culture effect is further enhanced (the activation is further enhanced). Play a role.

The culture tank 6 is preferably installed near the reaction tank 1 or the circulation tank 2. Further, the reactor tank 8 can be installed in the reaction tank 1 and / or the circulation tank 2 or the like.

The amount of liquid fed to the reaction tank of the culture circuit 7 is preferably in the range of 10 to 50 vol% with respect to the amount of waste water.

In this example, it is also preferable to feed the culture solution to each tank (eg, adjusting tank) in the preceding step of the reaction tank.

The reactor tank 8 may be filled with granules composed of a mixture containing at least humic substances and substances having an andesite or rhyolite composition in an activated or unstable state. preferable.

In the present specification, a humus is a mixture of humus and a humus precursor, and a humus precursor is a general term for an intermediate substance in the process of converting an organic matter into a humus.

When the culture solution containing the microorganisms or the metabolites of the microorganisms cultured in the culture tank filled with such a substance is sent to the reaction tank through the culture circuit 7, The microorganisms are activated, which makes it possible to perform regular treatment even if the properties of the wastewater change, and it is also possible to adsorb, occlude, or decompose difficult-to-decompose substances, and prevent sludge foaming in the reaction tank. . Furthermore, the culture circuit serves as a seed sludge supply source for soil bacteria.

As the reactor tank 8, for example, FIG.
The structure shown in FIG. FIG. 4 is a schematic sectional view showing an embodiment of the reactor used in the present invention.

In FIG. 4, reference numeral 81 denotes a reactor tank main body, which has an inflow port 82 for receiving the concentrated liquid separated in the ultrafiltration membrane 3 at the upper portion and has a concentrated reconstituted bacterial group at an intermediate position. It has an outlet 83 for taking out sludge. 83A is an outlet valve.

Reference numeral 84 is a filling portion filled with a granular filler (pellet) made of a mixture containing at least the aforementioned humus and a substance having an andesite or rhyolite composition in an activated or unstable state. Is.

Reference numeral 85 denotes an inner cylinder which is mounted in the main body 81, and perforated plates 85A and 85B are mounted on the upper and lower parts thereof.

The filling portion 84 is formed in the inner cylinder 85. In this embodiment, it is formed in multiple stages, but is not particularly limited. Reference numeral 86 is a gap formed between the main body 81 and the inner cylinder 85, and it is sufficient if the culture solution can be circulated in the main body.
87 is a fixing part for fixing the inner cylinder 84 to the main body 81.

Reference numeral 88 indicates the filling portion 84 below the filling portion 84.
An air diffuser capable of supplying air from a blower 89. The main purpose of supplying the air is to improve the contact between the concentrate and the filler.

Reference numeral 89 is a sludge extraction valve, and 90 is a liquid level sensor for detecting the maximum liquid level (HWL), the filler immersion level (ML), the minimum liquid level (LWL) and the like.

The main body 81 receives the concentrated liquid separated by the ultrafiltration membrane 3 from the inlet port 82 and the maximum liquid level (H
When it reaches WL), stop the liquid transfer. Next, air is supplied from the air diffuser 88 to the filling portion 84 to form a rising liquid flow in the inner cylinder 85, and the concentrated liquid and the filler are brought into contact with each other. The liquid in the upper portion of the inner cylinder 85 descends through the gap 86. In this way, the concentrated liquid circulates in the main body 81.

The concentrate is contacted with the filler and activated to activate the phenol metabolism function of the soil bacteria group contained in the concentrate to produce the compound.

The activation period is preferably in the range of 24 to 48 hours, and the activated culture solution is discharged from the outflow port 83. The sludge accumulated in the lower part of the main body is extracted from the sludge extraction valve 90.

Example 2 This example is an example of an apparatus for preventing the generation of odor in the previous step of the reaction tank, and the example shown in FIG. 2 can be given.

FIG. 2 is a block flow sheet showing another embodiment of the waste water treatment equipment according to the present invention. In FIG. 2, 10 is a drainage discharge source, 11 is a raw water tank (including a sand basin, etc.) for storing drainage, and 12 is an adjusting tank for buffering changes in the properties of drainage. Further, 13 is a circulation circuit 4 for a part of the concentrated liquid separated by the ultrafiltration membrane in the drainage source 10.
A return circuit for returning with or without passing through, 14 is the raw water tank 1
1 is a returning circuit for returning to 1, and 15 is a returning circuit for returning to the adjusting tank 12. The return circuits 13, 14, 15 are the reaction tank 1
It may be via the return circuit 5 to.

In this embodiment, the return circuits 13 and 1
It may be returned to any one of the drainage discharge source 10, the raw water tank 11, and the adjustment tank 12 by using any one of the return circuits 4 and 15, but is preferably returned to the drainage discharge source 10. , And more preferably to return all.

Wastewater discharge source 10, raw water tank 11, adjusting tank 1
The total amount returned to 2 is 10 to 200 vol with respect to the amount of wastewater.
% Is preferable.

By returning these, the drainage source 1
0, the odorous components generated from the raw water tank 11 and the adjusting tank 12 are adsorbed and absorbed by the sludge to prevent the generation of odors.

As a method of returning the waste water to the discharge source 10, in the case of public sewers, a return pipe can be installed in the upper space inside the buried sewer pipe and used to return. In the case of human waste, it can be returned to the toilet, collection tank, or lorry of each house. In the case of factory wastewater, it can be returned to the discharge source or discharge route of each factory.

Further, the return to the raw water tank 11 or the adjusting tank 12 can be returned to the sewage treatment or the excrement processing because the raw water tank and the adjusting tank are provided as structural standards.

In any of the above cases, it is more preferable to add a facility capable of supplying air. This is because it can play the role of a reaction tank.

In FIG. 2, the parts having the same signs as in FIG.
Since the configurations are the same, the description thereof will be omitted.

In this example, it is also preferable to return the culture solution to the raw water tank or the adjusting tank. This is because it can promote the activation of sludge in the reaction tank.

Embodiment 3 This embodiment is an example of an apparatus for preventing the generation of odor in the previous step of the reaction tank as in the case of Embodiment 2, but differs from Embodiment 2 in the means for preventing the generation of odor. The example shown in FIG.

FIG. 3 is a block flow sheet showing another embodiment of the waste water treatment equipment according to the present invention. In FIG. 3, reference numeral 20 is a thickener for withdrawing the concentrated liquid separated by the ultrafiltration membrane from the circulation tank 2 to further concentrate it. The reactor tank 8 may be added in order to further improve the thickening property of the thickener 20.

Reference numeral 21 is a dehydrator for chemical-free dehydration of the sludge concentrated by the thickener 20. After dehydration, low temperature drying or sun drying may be performed.

Reference numeral 22 is a return circuit for returning the non-chemically-injected dehydrated cake or the dried sludge obtained by drying the cake to the drainage source 10, 23 is a return circuit for returning to the raw water tank 11.
Is a return circuit for returning to the adjusting tank 12.

In the present embodiment, the return circuits 22, 2
It may be returned to any one of the drainage discharge source 10, the raw water tank 11, and the adjustment tank 12 using any one of the return circuits 3 and 24, but is preferably returned to the drainage discharge source 10. , And more preferably to return all.

By returning these, the drainage source 1
0, the odorous components generated from the raw water tank 11 and the adjusting tank 12 are adsorbed and absorbed by the sludge to prevent the generation of odors.

In FIG. 3, the parts having the same signs as in FIG.
Since the configurations are the same, the description thereof will be omitted.

According to this embodiment, since the solid sludge is returned, the amount of treated water in the system can be reduced and the amount of treated water in each system can be reduced as compared with the case where liquid sludge is returned as in the embodiment 2 shown in FIG. Since the capacity can be reduced, the cost of the entire device can be reduced and the site area can be reduced.

Further, in the present embodiment, compared with incinerating the dehydrated cake, not only the cost is saved but also the sludge can be effectively used.

Furthermore, in the present embodiment, the use of soil bacteria makes the sludge huge and agglomerates to improve the solid-liquid separation property, and therefore chemical free dehydration is possible.

Therefore, even if the dehydrated cake or the like is returned to the raw water tank or the like, since it is a non-chemical injection, various harmful effects (for example, microbial activity in the reaction tank is inhibited, and excess sludge in the system causes accumulation of sludge in the system). There is no increase). In the past, polymer flocculants and inorganic flocculants were always used in dehydration, but using polymer flocculants has the adverse effect of inhibiting microbial activity in the reaction tank, and using inorganic flocculants results in inorganic flocculants. There is an adverse effect that sludge in the system increases due to excessive accumulation of components.

Further, there is also an effect that sludge can be used as a fertilizer by allowing non-chemical injection dehydration. The effect of the present embodiment is remarkable as compared with the conventional case where sludge cannot be used as a fertilizer when a chemical is used for dehydration.

[0076]

[Experimental Example] The present invention will be described in more detail with reference to Experimental Examples of the present invention.

Experimental Example 1 (apparatus used in the experiment) The apparatus shown in FIG. 1 was modified and used in the experiment.

That is, in the preceding step of the reaction tank, the receiving sand settling tank (1
2.21m ^3), provided with raw water storage tank (80 m ^3).

The reaction tank 1 is the first reaction tank (55.5 m).
³ ), aeration tank (31.8 m ³ × 3 tank), second reaction tank (1
It was divided into 6 m ³ ). The circulation tank 2 was 14 m ³ .

As the ultrafiltration membrane, a flat membrane UFP type was used, and the total membrane area was 25.2 m ² .

(Operating conditions) The operating conditions were set as follows.

(1) Raw water: mixed human waste human waste 17 m ³ / D + septic tank sludge 3 m ³ /
D Mixed human waste BOD 12500 ppm Mixed human waste pH 7 to 8 (2) Membrane operation conditions Inlet pressure 2.6 to 3.0 kg / cm ² Outlet pressure 0.2 to 0.5 kg / cm ² Temperature 25 ° C. Circulating water volume 80 m ³ / Hr Operation period 36 months (3) Comparative operation and operation of the present invention At the point of 11 months after the comparison operation, the culture tank and the culture circuit of the present invention are provided to conduct a long-term experiment to confirm whether the effects of the present invention are confirmed. went.

The reason why such a long-term experiment was carried out is because it was judged in the short-term that it was not possible to confirm whether or not the present invention was completed until it was industrially applicable.

(4) Specifications of Culture Tank and Culture Circuit An above-ground reactor tank was used as the culture tank, and a 1 m ³ tank was used as the reactor tank.

The reactor tank shown in FIG. 4 was used, and the culture time of the concentrated solution was 500 liter / 24 hr.

Specifically, 500 liter / D of the culture solution was returned to the first reaction tank, and the uncultured concentrated solution was returned to the circulation tank by 500 times.
The culture solution and the uncultured solution were exchanged by 500 liters each by introducing liter / D for culturing.

(Results of Operation) BOD and pH of the membrane permeated water are treated water conditions (BOD 10 ppm or less, pH 5.8 to 8.
Although 6) was satisfied, the amount of water permeated through the membrane (flux) changed.

In the membrane treatment, this membrane permeated water amount (flux)
Since this is an index for evaluating the performance, the increase / decrease in this water amount was investigated.

Further, the membrane is regularly cleaned with a chemical solution, and
When the amount of water permeated through the membrane was significantly reduced, open frame cleaning was performed to disassemble and clean the membrane.

Since the open frame cleaning is complicated in terms of work, it is preferable that the number of flat membranes applied to an actual apparatus is small, and since it becomes an important index in performance evaluation, the amount of permeated water (flux) described above is used.
At the same time, the number of times the frame was washed was also examined.

The results are shown in FIG.

(Evaluation) As shown in FIG. 5, the membrane flux gradually increases from the time when the culture solution is returned from the culture circuit to the first reaction tank, and in particular, it tends to increase remarkably from the 8th month after the start of the culture solution return. It was found to be used.

It was also found that the number of times of open frame washing decreased immediately after the start of returning the culture solution, and the number of times of open frame washing became 0 20 months after the start of returning the culture solution, showing a surprising effect.

Further, it has been found that the film life is extended more than twice by the present invention.

Further, an experiment was also conducted in which the circulating sludge was returned to the receiving sand settling tank or the raw water storage tank. As a result, it was found that after returning the culture solution, the manure odor was significantly reduced.

Experimental Example 2 This experimental example is an example in which the present invention is applied to an apparatus for treating gray water by treating gray water in Hospital S.

(Apparatus used for experiment) In the apparatus shown in FIG. 1, a raw water tank (8.5 m ³ ) and a controlled aeration tank (50.9 m ³ ) were provided in the preceding step of the reaction tank 1.

[0098] volume of the reaction vessel is 10 m ^3, the capacity of the circulation tank was set to 6.9 m ^3.

A flat membrane UFP type was used as the ultrafiltration membrane, and the total membrane area was 37.8 m ² .

(Operating conditions) The operating conditions were set as follows.

[0102] (1) raw water: wastewater wastewater ^{85m 3 / D BOD 100ppm (2} ) film operating conditions inlet pressure 4.0 kg / cm ² outlet pressure 0.5 kg / cm ² Temperature At circulating water 75 m ³ / Hr operating period 10 months (3) Comparative operation and operation of the present invention After the lapse of 3 months from the comparative operation, the effect of the present invention was confirmed by providing the culture tank and culture circuit of the present invention. The purpose of the long-term experiment is the same as in Experimental Example 1.

(4) Specifications of culture tank and culture circuit The culture tank was 5 m ³ (the existing sludge storage tank was diverted), and the reactor shown in FIG. 4 was immersed therein.

The amount of the culture solution returned to the adjusted aeration tank was set to be about 30% (25 m ³ / D) with respect to the amount of waste water.

(Operation result) BOD of membrane permeated water is 1 ppm
Below, the pH was in the range of 7.2-7.4. The amount of water permeated through the membrane and the number of times of open frame cleaning are as shown in FIG.

(Evaluation) As shown in FIG. 6, in the comparative experiment before the culture circuit was provided, the average amount of water permeated through the membrane was a low value of 39 m ³ / D, and the open frame cleaning was required about once a month.

On the other hand, according to the present invention, the amount of water permeated through the membrane increased to an average of 47.6 m ³ / D. In addition, the number of times of open frame cleaning was also reduced to once every 2-3 months.

Further, it has been found that the film life is extended more than twice by the present invention.

Experimental Example 3 In Experimental Example 1, the concentrated sludge was extracted from the circulation tank, concentrated with a thickener, and then dehydrated without chemical injection.

When the dewatered cake was returned to the receiving sand basin and the raw water storage tank, the manure odor from the receiving sand basin and the raw water storage tank was significantly reduced.

The same effect was obtained even when the above dehydrated cake was dried in the sun and returned in the same manner.

[0111]

EFFECTS OF THE INVENTION According to the present invention, the reaction system in the reaction tank is always directed in a fixed direction by recovering the microbial activity in the reaction tank even if the drainage property changes or the hardly decomposable substance accumulates. In this way, it is possible to provide a wastewater treatment apparatus using an ultrafiltration membrane in which the number of times of membrane cleaning naturally decreases and the life of the membrane itself also increases as a result.

Further, according to the present invention, it is possible to provide a wastewater treatment apparatus using an ultrafiltration membrane which can solve the problem of odor from the previous step of the reaction tank when treating sewage, human waste and the like. .

The apparatus of the present invention can be applied not only to new construction but also to improvement of existing treatment facilities.

[Brief description of drawings]

FIG. 1 is a block flow sheet showing an embodiment of a wastewater treatment device according to the present invention.

FIG. 2 is a block flow sheet showing another embodiment of the waste water treatment apparatus according to the present invention.

FIG. 3 is a block flow sheet showing another embodiment of the waste water treatment apparatus according to the present invention.

FIG. 4 is a schematic cross-sectional view showing an embodiment of the reactor used in the present invention.

FIG. 5 is a graph showing the results of Experimental Example 1.

FIG. 6 is a graph showing the results of Experimental Example 2.

[Explanation of sign]

 1: Reaction tank 2: Circulation tank 3: Ultrafiltration membrane 4: Circulation circuit 5, 13, 14, 15: Return circuit 6: Culture tank 7: Culture circuit 8: Reactor tank 9: Auxiliary culture circuit 10: Emission source 11 : Raw water tank 12: Adjustment tank 20: Thickener 21: Dehydrator 22, 23, 24: Return circuit

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[Procedure amendment]

[Submission date] June 23, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0048

[Correction method] Change

[Correction content]

The filling portion 84 is formed in the inner cylinder 85. In this embodiment, it is formed in multiple stages, but is not particularly limited. Reference numeral 86 is a gap formed between the main body 81 and the inner cylinder 85, and it is sufficient if the culture solution can be circulated in the main body.
87 is a fixing part for fixing the inner cylinder 85 to the main body 81.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0049

[Correction method] Change

[Correction content]

Reference numeral 88 is an air diffuser provided below the filling section 84 and capable of supplying air from the blower 89 to the filling section 84. The main purpose of supplying the air is to improve the contact between the concentrate and the filler.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0050

[Correction method] Change

[Correction content]

Reference numeral 90 is a sludge extraction valve, and 91 is a liquid level sensor for detecting a maximum liquid level (HWL), a filler immersion level (ML), a minimum liquid level (LWL), and the like.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0092

[Correction method] Change

[Correction content]

(Evaluation) As shown in FIG. 5, the membrane flux gradually increases from the time when the culture solution is returned from the culture circuit to the first reaction tank, and in particular, it tends to increase remarkably from the 8th month after the start of the culture solution return. the shows Tei Rukoto was found.

[Procedure Amendment 5]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

[Figure 1]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akira Tokishita 5-6-4 Tsukiji, Chuo-ku, Tokyo Mitsui Engineering & Ships Engineering Co., Ltd.

Claims (8)

[Claims] 1. A reaction tank for treating wastewater with a microorganism, a circulation tank formed integrally with or separately from the reaction tank, and a suspension after the reaction is separated into a membrane permeated water and a concentrated liquid by using a pressure as a driving force. A circulation circuit having an ultrafiltration membrane that returns the concentrated solution separated in the ultrafiltration membrane to the circulation tank, and a part of the concentrated solution through the reaction with or without the circulation circuit. A return circuit for returning into the tank, and a part of the concentrated solution separated in the ultrafiltration membrane is introduced to substantially reactivate the microorganisms in the concentrated solution in the culture tank and then into the reaction tank. A wastewater treatment apparatus using an ultrafiltration membrane, which has a culture circuit for returning. 2. A reaction tank for treating wastewater with a microorganism, a circulation tank formed integrally with or separately from the reaction tank, and a suspension after the reaction is separated into a membrane permeated water and a concentrated liquid by using a pressure as a driving force. A circulation circuit for returning the concentrated liquid separated in the ultrafiltration membrane to the circulation tank, and a part of the concentrated liquid separated in the ultrafiltration membrane for the circulation circuit. And a return circuit for returning the reaction tank to the previous step of the reaction tank with or without intervening, to guide a part of the concentrated solution separated in the ultrafiltration membrane to substantially eliminate microorganisms in the concentrated solution. A wastewater treatment device using an ultrafiltration membrane, comprising a culture circuit which is reactivated in a culture tank and then returned to the reaction tank. 3. A reaction tank for treating waste water with a microorganism, a circulation tank formed integrally with or separately from the reaction tank, and a suspension after the reaction is separated into a membrane permeated water and a concentrated liquid by using a pressure as a driving force. A circulation circuit for returning the concentrated liquid separated in the ultrafiltration membrane to the circulation tank, and a part of the concentrated liquid separated in the ultrafiltration membrane for the circulation circuit. Return circuit for returning to the inside of the reaction tank with or without, and a cake obtained by chemical-free dehydration of a part of the concentrated solution separated in the ultrafiltration membrane or the cake is dried at low temperature or in the sun. A return circuit for returning the dried sludge obtained in the above step to the previous step of the reaction tank, and the reaction after the microorganism in the concentrate is substantially reactivated in the culture tank by guiding a part of the concentrate. Exclusion using an ultrafiltration membrane characterized by having a culture circuit for returning it to the tank Processing apparatus. 4. A pretreatment step of a reaction tank for returning the concentrated liquid separated in the ultrafiltration membrane is at least a discharge source of wastewater, a raw water tank for storing the wastewater, or an adjusting tank for buffering a change in the properties of the wastewater. It is any one, The wastewater treatment equipment using the ultrafiltration membrane of Claim 2 or 3 characterized by the above-mentioned. 5. A reactor tank is provided separately from the culture tank,
The reactor tank is filled with a granular material comprising a mixture containing at least a humic substance and a substance having an andesite or rhyolite composition in an activated or unstable state. 5. The ultrafiltration according to claim 1, further comprising an auxiliary culture circuit for reactivating the microorganisms in the concentrated liquid introduced from the culture tank in the reactor tank and then returning the microorganisms to the culture tank. Wastewater treatment equipment using a membrane. 6. A reactor tank is provided in a culture tank, and a mixture containing at least a humic substance and a substance having an andesite or rhyolite composition in an activated state or an unstable state is used in the reactor tank. The reactor tank is filled with the following granular material, and the auxiliary tank has a supplementary culture circuit for reactivating the microorganisms in the concentrated liquid introduced from the culture tank to the reactor tank and then returning to the culture tank. A wastewater treatment device using the ultrafiltration membrane according to claim 1, 2, 3, or 4. 7. A culture tank is a reactor tank, and the reactor tank is composed of a mixture containing at least humic substances and substances having an andesite or rhyolite composition in an activated or unstable state. Fill the granules,
2. A part of the concentrated liquid separated by the ultrafiltration membrane is introduced into the reactor tank to reactivate the microorganisms in the concentrated liquid in the reactor tank.
A wastewater treatment device using the ultrafiltration membrane described in 2, 3, or 4. 8. A main body of a reactor tank having an inlet for receiving a concentrated liquid separated by an ultrafiltration membrane in an upper portion and an outlet for taking out a concentrated sludge containing reactivated bacteria in an intermediate position. And a humic substance in the body, and a filling portion filled with a granular body made of a mixture containing at least a substance having an andesite or rhyolite composition in an activated state or an unstable state, and a filling portion of the filling portion. 8. A wastewater treatment apparatus using an ultrafiltration membrane according to claim 5, 6 or 7, characterized in that it has an air diffuser provided below it to supply air to the filling section.