JP4506574B2 - Human wastewater treatment equipment - Google Patents

Description

  The present invention relates to a septic tank compatible human waste treatment apparatus, and more particularly to a human wastewater treatment apparatus capable of significantly reducing the amount of excess sludge to be dewatered.

  Conventionally, human waste processing facilities have been aimed at processing high-concentration human waste pollutants at a high level, but in recent years, flushing of household toilets has progressed rapidly, and as a result, the amount of urine to be pumped has decreased. . Instead, the amount of combined septic tank sludge, represented by agricultural settlement wastewater treatment facilities, has increased rapidly, and along with this, the septic tank sludge compatible type that can treat septic tank sludge together with human waste. Facilities are required. In response to such social demands, many septic tank-compatible human waste treatment facilities have been proposed.

  However, since a large amount of excess sludge is generated from such a human waste treatment facility, the disposal of this sludge is currently the biggest problem. These surplus sludge is dehydrated with a dehydrator after adding a dehydrating aid, and then disposed of by landfill or incineration.

  However, when landfilling dewatered sludge, the increase in processing costs becomes a problem due to a decrease in disposal sites. In addition, from the viewpoint of preventing environmental pollution in recent years, guidance has been given to prohibit the incineration of sludge from human waste treatment plants. For this reason, the problem of sludge disposal is becoming more serious.

  Under such circumstances, for example, in Patent Document 1, pre-reaction means for oxidizing the mixed liquid of raw urine and septic tank sludge is provided in the previous stage of the nitrification denitrification treatment process in the conventional human waste treatment facility to stabilize the sludge. In order to reduce the amount of excess sludge generated by improving the solid-liquid separation property, a system has been proposed.

However, with this system,
1) The amount of microorganisms in the pre-reaction tank cannot be properly controlled, and the process may become unstable.
2) The effect of reducing excess sludge generation is insufficient.
There was a problem.
JP 11-33591 A

  An object of the present invention is to provide a human wastewater treatment apparatus that is stable in the pre-reaction means and is excellent in the effect of reducing excess sludge.

  The human wastewater treatment apparatus of the present invention includes at least a reaction means for adding a flocculant to an urine wastewater and oxidizing it, including at least raw urine and septic tank sludge, and a supernatant and sludge for the human wastewater treated by the prereaction means. A first solid-liquid separation means for solid-liquid separation, a dehydration means for dewatering sludge separated by the first solid-liquid separation means, and a supernatant liquid separated by the first solid-liquid separation means. Reaction means for nitrification denitrification treatment, second solid-liquid separation means for solid-liquid separation of the suspension introduced from the reaction means into sludge and treatment liquid, and sludge generated in the reaction means for the pre-reaction A first return means for returning to the previous step of the means or the pre-reaction means, and at least a part of the sludge separated by the first solid-liquid separation means from the upstream of the dehydration means. A second return means for returning to the previous step of the reaction means; And Bei, wherein the second return means, wherein said first solid-liquid separation means separated sludge solubilization processing means for solubilizing at least part of the sludge is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the process by a pre-reaction means is stable, and it can provide the reduction effect of a surplus sludge, and can provide the wastewater treatment apparatus.

  The present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram for explaining a human wastewater treatment apparatus according to an embodiment of the present invention.

  This human wastewater treatment apparatus can receive both raw urine and septic tank sludge, and a pre-reaction tank 3 having a first pre-treatment means 1, a second pre-treatment means 2, and a pre-reaction means. A biological reaction tank 6 comprising a first solid-liquid separation means 5, a reaction means for nitrification denitrification treatment, a second solid-liquid separation means 7, an activated carbon treatment means 8, and a dehydrator 9 comprising a dehydration means. And a sludge solubilization device comprising a sludge solubilization treatment means.

  The first pretreatment means 1 into which live urine is introduced and the second pretreatment means 2 into which the septic tank sludge is introduced communicate with the prereaction tank 3 respectively. The pre-reaction tank 3 is provided with an adding means 4 for adding the flocculant into the pre-reaction tank 3. The pre-reaction tank 3 communicates with the first solid-liquid separation means 5, and the first solid-liquid separation means 5 communicates with the biological reaction tank 6. The solid-liquid separation means 5 communicates with the dehydrator 9 via the dehydration line L100, and the pre-reaction tank 3 via the sludge return line (second return means) L200 branched from the dehydration line L100. Also communicate with. The sludge solubilizer is provided in the sludge return line L200.

  The dehydrator 9 communicates with the biological reaction tank 6. The biological reaction tank 6 and the pre-reaction tank 3 communicate with each other via a sludge return line (first return means) L300. The biological reaction tank 6 communicates with the second solid-liquid separation means 7, and a sludge return line L 400 is provided between the biological reaction tank 6 and the solid-liquid separation means 7. The second solid-liquid separation means 7 communicates with the activated carbon treatment means 8, and the activated carbon treatment means 8 has treated water discharge means (not shown) for discharging treated water that has passed through the activated carbon treatment means 8. Is provided.

  The first pretreatment means 1 introduces raw urine to remove impurities, and the second pretreatment means 2 introduces septic tank sludge to remove impurities. Although FIG. 1 shows an example in which the preprocessing units 1 and 2 are separately provided, the preprocessing units 1 and 2 may be combined into a single unit.

  In the pre-reaction tank 3, the urine waste water containing the raw urine and the septic tank sludge treated by the pre-treatment means 1 and 2 is oxidized prior to the biological reaction (nitrification denitrification treatment) in the biological reaction tank 6 in the subsequent stage. To do. Specifically, the solid matter separation is improved by oxidatively degrading organic matter contained in human waste wastewater to reduce liquid viscosity, and the generation of malodor is suppressed by oxidatively degrading high molecular organic matter, Stabilize sludge properties. The purpose of the present invention is to oxidize and decompose the solubilized sludge introduced from the sludge solubilizer described in detail later in the pre-reaction tank 3.

  Examples of the flocculant used in the pre-reaction tank 3 include inorganic flocculants such as polyaluminum chloride, ferric chloride, and polyiron, and polymer flocculants.

At this time, as shown in FIG. 1, the flocculant can be directly added to the pre-reaction tank 3 from the adding means 4. However, the method for adding the flocculant is not limited to this, and the human wastewater treatment apparatus can be separately provided with a flocculant tank for adding the flocculant. Examples of this are shown in FIGS.
The human wastewater treatment apparatus shown in FIG. 2 is provided with a coagulation tank 13 at the rear stage of the pre-reaction tank 3, and this coagulation tank 13 is provided with a coagulant adding means 4. The wastewater from the pretreatment means 1 and 2 is temporarily stored in the pre-reaction tank 3 and then introduced into the coagulation tank 13 where the coagulant is added from the addition means 4.
The human wastewater treatment apparatus shown in FIG. 3 is provided with a coagulation tank 13 in the previous stage of the pre-reaction tank 3, and the coagulation tank 13 is provided with a coagulant adding means 4. The waste water from the pretreatment means 1 and 2 is first introduced into the coagulation tank 13, where the coagulant is added from the addition means 4 and then introduced into the prereaction tank 3. 2 and 3, when a separate flocculation tank is provided, a plurality of flocculation tanks and corresponding addition means are provided for further improvement of the flocculation effect, and different flocculants are sequentially added in each step. A method can also be taken.

  In the first solid-liquid separation means 5, the urine wastewater oxidized in the pre-reaction tank 3 is solid-liquid separated into supernatant liquid and sludge. The separation method in the first solid-liquid separation means 5 can be, for example, a normal gravity sedimentation type. When the separation is insufficient, or when it is necessary to obtain a higher concentration of sludge in order to increase the efficiency of the sludge solubilizer at the subsequent stage, an appropriate solid-liquid separation means may be used.

  The biological reaction tank 6 following the first solid-liquid separation means 5 is mainly constituted by a nitrification / denitrification treatment tank, and performs a nitrification / denitrification treatment on the supernatant liquid separated by the solid-liquid separation means 5. The configuration of the nitrification / denitrification treatment tank is not particularly limited. The treatment liquid in the biological reaction tank 6 is introduced into the second solid-liquid separation means 7 as a suspension. The biological reaction tank 6 is provided with a return line L300 for returning the sludge generated here to the previous reaction tank 3. The return means is not limited to this, and sludge is added to the pre-process of the pre-reaction tank 3, for example, the second pre-process means 2 or a line for connecting the pre-process means 2 and the pre-reaction tank 3. A return line may be provided so as to be returned.

  The second solid-liquid separation means 7 separates the supernatant liquid (suspension) processed in the biological reaction tank 6 into sludge and processing liquid. As a separation method in the second solid-liquid separation means 7, for example, a gravity sedimentation method, membrane separation, or the like can be used, and may be appropriately selected according to properties required for the treatment liquid. As shown in FIG. 1, the solid-liquid separation means 7 is provided with a return line L400 for returning the separated sludge to the biological reaction tank 6. However, the return means is not limited to this, and the solid-liquid separation means 7 may be provided with a return means for returning the sludge separated here to the pre-reaction tank 3 or its pre-process. Further, the solid-liquid separation means 7 may be provided with a feeding means for feeding the solid-liquid separated sludge to a sludge solubilizer or a dehydrator 9 described later. Furthermore, a separate dehydrator can be provided in the solid-liquid separation means 7, and the separated sludge can be dehydrated and discharged as dehydrated sludge.

  The treatment liquid separated by the second solid-liquid separation means 7 is further subjected to advanced treatment as necessary and discharged as treated water. In FIG. 1, the activated carbon treatment means 8 is shown as an example of the advanced treatment means, but the present invention is not limited to this method.

  The sludge separated by the first solid-liquid separation means 5 is introduced into the dehydrator 9 through the dehydration line L100 provided in the solid-liquid separation means 5. The sludge return line L200 is bypassed in the dewatering line L100, and a part of the sludge passing through the dewatering line L100 is introduced into the sludge solubilizer via the sludge return line L200. The sludge dehydrated by the dehydrator 9 is discharged as dehydrated sludge. In the dehydration treatment, a dehydration aid can be added to the sludge. The water discharged from the sludge by dehydration is introduced into the biological reaction tank 6 and is used for the nitrification denitrification treatment and the post-treatment together with the supernatant liquid from the first solid-liquid separation means 5.

Next, the sludge solubilizer will be described.
This sludge solubilizer includes an alkali treatment tank 10 having an alkali treatment means and a biological solubilization tank 12 having a biological solubilization means.

  Sludge bypassed from the dehydration line L100 is introduced into the alkali treatment tank 10. The alkali treatment tank 10 is provided with an alkali agent adding means 11 for adding an alkali agent to the sludge.

  In the alkali treatment tank 10, the sludge is subjected to alkali treatment by adding a small amount of an alkali agent to the sludge and allowing it to stay for a predetermined time. By this treatment, the cell constituent components of various microorganisms constituting the sludge can be modified into a form that is susceptible to biological degradation (hereinafter referred to as an alkali-solubilizing component).

  Examples of the alkali agent for the alkali treatment include, but are not limited to, sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, sodium carbonate, sodium bicarbonate, and the like.

  The addition amount of the alkaline agent can be appropriately determined according to the type, concentration, introduction amount and state of sludge. In the present invention, since the sludge after alkali treatment is biologically solubilized at a later stage, it is possible to suppress the alkaline agent to a small amount as compared with the case where the sludge is solubilized only by the alkali treatment.

  The alkali treatment may be performed while heating, but it is more preferable to perform the treatment at room temperature. In the present invention, since the latter biological solubilization means is used in combination, a sufficient effect can be obtained even if the alkali treatment is carried out at room temperature, thereby suppressing the heating cost. The alkali treatment tank 10 can be a complete mixing type or an extrusion flow type. In particular, the extrusion flow type is preferable because more efficient processing such as further cost reduction by reducing the alkaline agent and size reduction of the tank by shortening the residence time can be expected.

  The alkali treatment tank 10 communicates with a biological solubilization tank 12 in which the sludge after the alkali treatment is anaerobic, oxygen-free, or fine under normal temperature and normal pressure. It is further solubilized by the action of sludge solubilizing bacteria under aerobic conditions. In addition, when the sludge after alkali treatment is exposed to aerobic conditions, there exists a possibility that the re-sludge of an alkali-solubilized component may arise. In order to avoid this, it is desirable to introduce the sludge after the alkali treatment into the biological solubilization tank 12 immediately without touching the air.

  The microorganisms (sludge solubilizing bacteria) involved in the solubilization of sludge in the biological solubilization tank 12 are mainly composed of sludge under anaerobic, oxygen-free or microaerobic conditions at normal temperature and pressure. Microorganisms that secrete proteases, amylases, and the like that degrade protein and carbohydrate as components and can use sludge components as nutrients are suitable, but are not particularly limited.

  In this sludge solubilizer, the sludge bypassed from the dewatering line L100 is introduced into the alkali treatment tank 10 via the sludge return line L200, and after being subjected to alkali treatment, subsequently introduced into the biological solubilization tank 12. And solubilized. The solubilized sludge (solubilized sludge) is returned to the pre-reaction tank 3 via the sludge return line L200, and again used for the oxidation treatment step and the subsequent step. As shown in FIG. 3, when the coagulation tank 13 is provided in the previous stage of the pre-reaction tank 3, the solubilized sludge may be returned to the coagulation tank 13 or may be returned to the pre-reaction tank 3. . This can be appropriately determined depending on the properties of the sludge and the treatment state of the solubilized sludge.

  FIG. 1 shows an example in which a sludge solubilizer is provided in the sludge return line L200 for returning sludge (solubilized sludge) to the pre-reaction tank 3, but this is not a limitation. A sludge return line for returning to the previous step of the reaction tank 3 may be provided, and a sludge solubilizer may be provided there.

  FIG. 1 shows an example in which the sludge return line L200 is bypassed from the dewatering line L100, but the return means is not limited to this, and the sludge is separated from the solid-liquid separator without going through the dewatering line L100. It is also possible to provide a sludge return line so as to be introduced directly from 5 into the alkali treatment tank 10.

  As described above, the solubilization rate in the biological solubilization tank 12 can be drastically improved by using the alkali treatment means and the sludge solubilization treatment means in combination. This is because sludge in a state in which the bacterial cells in the sludge are destroyed and the intracellular fluid is eluted can be introduced into the biological solubilization tank 2 by pretreatment with an alkaline agent in advance. Accordingly, the residence time of the sludge in the solubilization tank 12 can be shortened, and the tank volume of the biological solubilization tank 12 can be reduced.

  Since the sludge solubilization in the biological solubilization tank 12 is performed under anaerobic, oxygen-free or microaerobic conditions, aeration is not required. Therefore, the biological solubilization tank 12 does not require a special additional facility for aeration, but a simple stirrer may be installed to increase the reactivity. Even when a stirrer is installed, the cost can be kept much lower than the aeration cost. Furthermore, in this invention, since sufficient effect is acquired even at normal temperature, heating is not required, and heating costs can be suppressed. For this reason, excess sludge can be reduced by a very simple and low running cost process.

  By the way, the alkaline treatment liquid flowing from the alkaline treatment tank 10 into the biological solubilization tank 12 is neutralized to some extent by performing treatment in the solubilization tank 12 under anaerobic, oxygen-free or microaerobic conditions. The Therefore, in the present invention, the acid for neutralizing the treatment liquid can be suppressed to a very small amount, or may not be necessary in some cases, so that the chemical cost for neutralization can be reduced or unnecessary. it can.

  Since the solubilized sludge treated in the sludge solubilizer is oxidized again in the pre-reaction tank 3, the organic matter in the solubilized sludge can be completely decomposed and removed oxidatively, and as a result, discharged. The amount of sludge can be significantly reduced. Further, the sludge treated in the sludge solubilizer (including sludge that is returned without being sufficiently solubilized) contains a large amount of microorganisms grown in the pre-reaction tank 3. Therefore, by returning this group of microorganisms to the pre-reaction tank 3, it is possible to suppress fluctuations in the amount of microorganisms in the pre-reaction tank 3 depending on the amount and state of human waste water, and to control the microorganisms to an appropriate amount. As a result, stable oxidation treatment can be realized.

  As described above, in the present invention, the amount of sludge introduced into the sludge solubilization treatment means (sludge solubilization treatment amount) can be changed to control the reduction amount of excess sludge and the pre-reaction means. The amount of microorganisms in can be controlled to stabilize the oxidation reaction. Moreover, control of the amount of microorganisms in a pre-reaction tank and control of the sludge solubilization processing amount can also be performed independently. An example of this is shown in FIG.

  The human wastewater treatment apparatus shown in FIG. 4 introduces sludge into the sludge solubilizer in such a manner that the sludge return line L200 bypasses the sludge from the dewatering line L100 and is introduced into the pre-reactor 3, and is branched from the sludge return line L200. And a branch line L201. The sludge bypassed from the dehydration line L100 is introduced into the pre-reaction tank 3 via the sludge return line L200, whereby the amount of microorganisms in the pre-reaction tank 3 can be stabilized. On the other hand, a part of the sludge passing through the sludge return line L200 is introduced into the sludge solubilizer via the branch line L201, subjected to biological solubilization treatment, and then pre-reacted via the sludge return line L200. Returned to tank 3. The amount of sludge returned or solubilized can be controlled by, for example, a valve or a pump. Thus, according to the human waste water treatment apparatus shown in FIG. 4, the amount of microorganisms in the pre-reaction tank and the amount of sludge solubilization can be controlled independently.

[Example]
EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to this.

(Example)
A urine wastewater treatment experiment was conducted using a human wastewater treatment apparatus having the same configuration as the apparatus shown in FIG. In this apparatus, the return sludge returned from the biological reaction tank was mixed with the urine wastewater composed of the septic tank sludge and raw urine pretreated in this apparatus and introduced into the pre-reaction tank. At this time, the mixing ratio of raw urine, septic tank sludge and return sludge was volume ratio, and raw urine: septic tank sludge: returned sludge = 3: 6: 1. The properties of the mixed solution in the pre-reaction tank were as follows.

pH: 7.6
BOD: 4790mg / L
COD: 3740 mg / L
SS: 6580 mg / L
TN: 1350mg / L
TP: 180 mg / L
Here, BOD indicates the biochemical oxygen demand, COD indicates the chemical oxygen demand, SS indicates the amount of suspended solids, TN indicates total nitrogen, and TP indicates total phosphorus.

  As the flocculant added to the pre-reaction tank, an iron-based flocculant was used as an inorganic flocculant, and the amount added was 0.1 vol% with respect to the mixed solution. The residence time in the previous reaction tank was 2 days.

  In addition, the alkali treatment tank and the biological solubilization tank constituting the sludge solubilizer were sealed, and only mechanical stirring was performed without aeration. Caustic soda (sodium hydroxide; NaOH) was used as the alkaline agent. Table 1 shows sludge solubilization treatment conditions. In Table 1, the amount of alkali agent added indicates the amount added per kg of dry sludge contained in the mixed solution.

(Comparative example)
Moreover, except that the sludge return line and the sludge solubilization device are not installed, the treatment of urine wastewater is carried out in the same manner as in Example 1 except that a human wastewater treatment device having the same configuration as in the example is used. The experiment was conducted.

  Table 2 shows the results of initial costs and running costs obtained in the examples and comparative examples. Table 2 also shows the results of the amount of excess sludge generated that had to be dehydrated and disposed of in the examples and comparative examples. In addition, the numerical value in Table 2 shows the result of an Example and a comparative example relatively, setting the result obtained by the comparative example to 1.

  As shown in Table 2, according to the human waste water treatment apparatus of the present invention, the amount of excess sludge to be disposed of by dehydration is significantly reduced compared with the comparative example without significantly increasing the initial cost. did it. As a result, surplus sludge disposal costs could be greatly reduced, which enabled operation at a lower running cost than the comparative apparatus.

  Next, in the apparatuses of Examples and Comparative Examples, the supernatant liquid separated by the first solid-liquid separation means was analyzed. The analysis results are shown in Table 3.

  As shown in Table 3, even if the solubilized sludge from the solubilization treatment apparatus is returned to the pre-reaction tank, no serious deterioration is observed in the properties of the treatment liquid (supernatant liquid). It was confirmed that the process was performed stably. In addition, destabilization of the nitrification / denitrification process in the biological reaction tank downstream of the first solid-liquid separation means and deterioration of solid-liquid separation in the first and second solid-liquid separation means were not detected. It was.

  As described above in detail, according to the present invention, the reaction in the pre-reaction tank can be stabilized and the amount of excess sludge generated can be significantly reduced in the human waste treatment plant having the pre-reaction tank. This is extremely effective for the maintenance of the human waste treatment plant, and its industrial value is great.

The block diagram for demonstrating the wastewater wastewater treatment apparatus which concerns on one Embodiment of this invention. The block diagram for demonstrating an example of the wastewater wastewater treatment apparatus which comprises a coagulation tank. The block diagram for demonstrating the other example of the manure wastewater treatment apparatus which comprises a coagulation tank. The block diagram for demonstrating the sludge solubilization apparatus provided in the branch line of a sludge return line, and a urine wastewater treatment apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... First pretreatment means, 2 ... Second pretreatment means, 3 ... Prereaction tank, 4 ... Addition means, 5 ... First solid-liquid separation means, 6 ... Biological reaction tank, 7 ... Second Solid-liquid separation means, 8 ... activated carbon treatment means, 9 ... dehydrator, 10 ... alkali treatment tank, 11 ... alkaline agent addition means, 12 ... biological solubilization tank, 13 ... coagulation tank, L100 ... dehydration line, L200, L300, L400 ... sludge return line, L201 ... branch line.

Claims (3)

A pre-reaction means for adding a flocculant to urine wastewater containing at least raw urine and septic tank sludge and oxidizing it;
First solid-liquid separation means for solid-liquid separation of human waste wastewater treated by the pre-reaction means into supernatant liquid and sludge;
Dehydration means for dewatering the sludge separated by the first solid-liquid separation means;
Reaction means for nitrifying and denitrifying the supernatant liquid separated by the first solid-liquid separation means;
Second solid-liquid separation means for solid-liquid separation of the suspension introduced from the reaction means into sludge and treatment liquid;
A first return means for returning the sludge generated by the reaction means to the pre-reaction means or a pre-process of the pre-reaction means;
A second return means for returning at least a part of the sludge separated by the first solid-liquid separation means from the upstream of the dehydration means to the pre-reaction means or a pre-process of the pre-reaction means,
The urine wastewater treatment apparatus, wherein the second return means is provided with sludge solubilization treatment means for solubilizing at least a part of the sludge separated by the first solid-liquid separation means.   In the sludge solubilization treatment means, an alkali treatment means for adding an alkali agent to the sludge separated by the first solid-liquid separation means for alkali treatment, and sludge treated by the alkali treatment means, anaerobically, The apparatus for treating wastewater from human waste according to claim 1, further comprising biological solubilizing means for biologically solubilizing and decomposing under anaerobic or microaerobic conditions.   The human wastewater treatment apparatus according to claim 1 or 2, wherein an addition means for adding the flocculant to the urine wastewater is provided in the front stage or the rear stage of the pre-reaction means.

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