JPH0647119B2 - Combined treatment method of human waste and septic tank sludge - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for treating human waste and septic tank sludge in combination.

[Prior Art] Among the conventional combined treatment methods of human waste and septic tank sludge, the one evaluated as the newest advanced process is:
This is a process called the high load denitrification membrane separation method. This is an ultrafiltration (UF) process after nitrifying and denitrifying a liquid mixture of human waste and septic tank sludge with a high volume load.
This is a process to obtain SS-zero biologically treated water by completely separating SS with a membrane.

[Problems to be Solved by the Invention]

However, although the conventional latest process is rational as a process for purifying sewage, the sludge treatment process is still old and has the following major drawbacks.

That is, since the sludge generation amount is extremely large at 10 to 15 kg SS / k and is difficult to dehydrate, the running cost and initial cost of the sludge dehydration / incineration process and the membrane separation process are large.

This point is a serious drawback when evaluated as a total process, and it cannot be said to be ideal unless the process solves this drawback.

It is an object of the present invention to provide a novel treatment process which can largely solve the drawbacks of the conventional state-of-the-art processes. Specifically, the present invention provides a treatment process that can significantly reduce the running cost and initial cost of the sludge dewatering / incineration process by significantly reducing the sludge generation amount.

Another object of the present invention is to establish a method for reducing the running cost and initial cost of the membrane separation step, which are problems of the conventional process.

[Means for Solving the Problems]

The present invention, by adding a polymer flocculant to human waste to aggregate and separate,
Both of the coagulation separation sludge and the concentrated sludge obtained by concentrating and separating the septic tank sludge are subjected to anaerobic digestion, and then membrane separation is performed, and the membrane permeate and the coagulation separator of the human waste are subjected to biological nitrification denitrification treatment. Further, the combined treatment method of human waste and septic tank sludge is characterized in that the treated water subjected to the biological nitrification denitrification treatment and the concentrated separation liquid of the septic tank sludge are further subjected to biological nitrification denitrification treatment. .

[Action]

The operation of the present invention will be described below with reference to FIG. 1 showing one embodiment.

Coagulant 2 for macromolecules is added to the human waste 1 from which coarse solid substances such as hair, rubber, plastics, and paper have been removed (referred to as decontamination urine).
(Cation type, amphoteric polymer, or combination of cation type and anion type polymer is suitable) is added and mixed,
The flocs produced are separated by a solid-liquid separation device 3 such as a screen, a sedimentation device, a centrifugal separation device, etc. and separated into a coagulation separation liquid 4 and a coagulation separation sludge 5. The coagulated separation sludge 5 is a fine particle in the removed urine 1.
It is an aggregate that integrates SS, colloid, and fiber (cellulose).

On the other hand, the septic tank sludge 6 from which coarse foreign matter has been removed in advance,
The liquid is concentrated by a solid-liquid separation device 7 such as a screen, a precipitation, a centrifugal separation, and separated into a concentrated separation liquid 8 and a concentrated sludge 9.

After that, both the coagulated separation sludge 5 of the removed urine 1 and the concentrated sludge 9 of the septic tank sludge 6 are supplied to the anaerobic digestion tank 10 and, after anaerobic digestion, membrane separation is performed by a membrane separation device 11 such as a UF membrane. Then, the membrane permeate 12 and the membrane-separated digested sludge 13 are separated.

The above operation is one of the new concepts of the present invention, and anaerobically both coagulated sludge obtained by coagulating separation of human waste and sludge obtained by solid-liquid separation of septic tank sludge separately from human waste. Sexually digested,
The concept of membrane separation is unique. Conventionally, a mixture of decontaminated urine 1 and septic tank sludge 6 is anaerobically digested as it is. Therefore, NH ₃ -N, H ₂ S in human urine significantly inhibits the anaerobic digestion reaction, and a large amount. Needed a digester tank of capacity.

Then, the sludge 5 that has been decontaminated and the coagulation separation sludge 5 and the septic tank sludge 6
The concentrated sludge 9 is anaerobically digested by maintaining the solids retention time (STR) in the anaerobic digestion tank 10 for a long time, and the organic matter is decomposed into gas mainly containing CH ₄ and CO ₂ and H ₂ O. To do.

Hydraulic retention time (HRT) in anaerobic digester 10 is 1
The digestion may be carried out for 5 days or more, and the digestion may be carried out by high temperature digestion, but medium temperature digestion at room temperature or 35 ° C to 37 ° C is preferable.
The RT is ideally set to infinity, preferably 100 days or more. By setting such conditions, 90% or more of the organic substances in the coagulation-separation sludge 5 and the concentrated sludge 9 are decomposed, and even 60% or more of the fiber components are decomposed. This is a surprising new finding.

For the purpose of maintaining the SRT of the anaerobic digestion tank 10, the subsequent membrane separation of digested sludge plays a very important role. The solid-liquid separation by the membrane is complete, the digestion sludge to the membrane permeate 12 and the outflow of the anaerobic digestion tank are zero, and the SRT in the anaerobic digestion tank 10 is recycled by recycling the membrane separation digestion sludge 13.
Because it can be maintained for a very long time. Reference numeral 14 is a drawing tube for an extremely small amount of undigested residue.

By the above operation, the organic matter in the coagulated separation sludge 5 of the removed urine 1 and the concentrated sludge 9 of the septic tank sludge 6 achieves a high degree of anaerobic digestion with a decomposition rate of 90% or more. The reason why organic matter is highly decomposed in this way is NH ₃ − which is a toxic substance.
In addition to the fact that N is reduced and the SRT can be made extremely long, hydrolyzing enzymes and solubilizing bacteria of various organic substances are blocked by the membrane and do not flow out of the system. It is presumed that this is because the persistent organic substances such as sludge cell walls are decomposed. In the conventional method of anaerobic digestion → precipitation separation of the mixture of human waste and septic tank sludge as it is, the cellulosic fibers are hardly decomposed and remain as undigested sludge.

Next, both the aggregated separation liquid 4 of the decontaminated urine 1 and the membrane permeation liquid 12 after anaerobic digestion are supplied to the undiluted biological nitrification and denitrification step 15, and BOD and TN are biologically analyzed. To remove it.
Then, solid-liquid separation (precipitation, centrifugation, membrane separation), preferably membrane separation with a membrane separation device 16 such as a UF membrane, separates into a membrane permeate 17 and a membrane separation activated sludge 18, and the membrane separation activated sludge is obtained. 18 is recycled to the biological nitrification and denitrification step 15.

Thus, according to the present invention, colloids, fine SS, and fiber components in human waste are highly aggregated and separated by the polymer flocculant 2, and further biological nitrification and denitrification is performed with the membrane permeate 12 after anaerobic digestion with zero SS. As a result of the process being configured for nitrogen treatment, the biological nitrification denitrification step 15 is supplied with little inert SS. Therefore, in the activated sludge MLSS of the biological nitrification and denitrification step 15, inactive S that does not cause any biological reaction
Almost no S content is contained, and as a result, the activated sludge SRT in the biological nitrification and denitrification step 15 can be maintained for a long time. This can significantly reduce the amount of excess sludge generated.

Reference numeral 19 is a drawing pipe for a very small amount of excess sludge, and the extracted excess sludge may be directly supplied to the anaerobic digestion tank 10 or may be removed and mixed with the urine 1 for coagulation separation. Also, septic tank sludge 6
The concentrated separated liquid 8 of can be supplied to the biological nitrification and denitrification step 15 and biologically treated.

Furthermore, as a preferred embodiment of the present invention, a purification treatment system for the coagulated separation liquid 4 of the decontaminated urine 1 and the membrane permeate 12 after anaerobic digestion and a purification treatment system for the concentrated separation liquid 8 of the septic tank sludge 6 are separated. It is to be.

That is, the coagulated separation liquid 4 and the coagulated separation sludge 5 of the removed urine 1 are
Soluble BOD, TN, etc. are present in the amount of several thousand mg /, whereas the concentrated separation liquid 8 of the septic tank sludge 6 is soluble BO.
Paying attention to the fact that D, TN, etc. are only a few 1000 mg /, both of the concentrated separation liquid 4 which is a high concentration organic wastewater and the membrane permeation liquid 12 after anaerobic digestion are subjected to a biological nitrification and denitrification process. After being supplied to 15 for biological treatment, the membrane is separated by a membrane separation device 16. On the other hand, since the concentrated separation liquid 8 of the septic tank sludge 6 has a low degree of pollution, it is mixed with the membrane permeation liquid 17 of the membrane separation device 16 and the second biological nitrification denitrification step 20.
And biological treatment.

The function of the second biological nitrification and denitrification step 20 is that the membrane permeate 1
7 and biologically highly removing a small amount of BOD and TN contained in the concentrated separated liquid 8 of the septic tank sludge 6, and the coagulant 21 in the second biological nitrification and denitrification step 20. It is possible to effectively remove COD, chromaticity, and PO ^- _3-4 by adding powdered activated carbon 22 and the like. The biologically treated water of the second biological nitrification denitrification step 20 is
Further, it is subjected to solid-liquid separation in any solid-liquid separation device 23, preferably a membrane separation device, and flows out as highly treated water 24.

It is also possible to mix the wastewater 25 in the site with the inflow liquid to the second biological nitrification denitrification step 20 and simultaneously perform biological treatment.

Thus, by using the second biological nitrification / denitrification step 20, the undiluted biological nitrification / denitrification step 15
However, since it is not diluted by the inflow of the septic tank sludge 6, it is possible to maintain a high temperature rise due to the heat of biological oxidation and reduce the load of water amount, so that it is possible to perform an efficient nitrification denitrification process with a small-capacity facility. Further, the load of water amount of the activated sludge on the membrane separation device 16 is reduced, and a large advantage is obtained that the required area of the membrane and the power cost are reduced.

〔Example〕

 Examples of the present invention will be shown below.

After removing impurities and fibers in human waste with a fine mesh screen, a cationic polymer (Ebagrose C104G,
250 mg / brand name) was added and the result of stirring for 30 seconds
A strong and large flock was formed, and the slanted wedge wire screen with an opening of 1 mm could easily separate the flock. The solid content of the separated sludge (coagulated separation sludge) was as high as 4.3%.

On the other hand, the solid concentration of the sludge obtained by concentrating and separating the septic tank sludge by the centrifugal concentrator was 4.2%.

Next, the mixed sludge (weight ratio 1: 1) of the above-mentioned coagulation separation sludge of night soil and concentrated sludge of septic tank sludge was supplied to an anaerobic digestion tank at a temperature of 35 ° C (the stirring inside the tank was mechanically performed). , HRT
Was set for 15 days, and sludge acid fermentation, solubilization, and methane fermentation were allowed to proceed.

The digested sludge flowing out from the anaerobic digester was completely separated by UF membrane, and the membrane-separated digested sludge was recycled to the anaerobic digester. Further, this membrane-permeated liquid was mixed with the aggregated separated liquid of night soil separated by the inclined wedge wire screen and supplied to the biological nitrification and denitrification step.

Since the anaerobic digestion sludge is completely separated by the UF membrane and recycled, and does not flow out of the system at all, the SRT of the anaerobic digestion tank can be set to 200 days or more. About 90% is decomposed and the undigested residue is 1.
It was an extremely small amount of 2 kg / k.

The water quality of the mixed liquid of the anaerobic digestive membrane separation liquid and the urine aggregation separation liquid supplied to the biological nitrification and denitrification step was as shown in Table 1.

Table 2 shows the operating conditions for the biological nitrification and denitrification process.

The water quality of the UF membrane permeate in the biological nitrification and denitrification step in Table 2 was as shown in Table 3.

Further, the concentrated separation liquid of the septic tank sludge is, together with the UF membrane permeation liquid, a sulfuric acid band of 1500 mg /, a powdered activated carbon of 600 mg /
Was added and treated in the second biological nitrification and denitrification step and the membrane separation step (hollow fiber membrane). The treated water quality is shown in the table −
4 shows.

It should be noted that during the 6-month continuous experiment of the biological nitrification and denitrification process, it was not necessary to withdraw excess sludge. The reason for this is that the inactive SS content of the influent is very small and MLS of activated sludge is
It is considered that since S also has a high concentration, the amount of excess sludge generated is very small.

〔The invention's effect〕

As described above, the present invention has the following outstanding effects.

Compared with the conventional process, the amount of sludge generated is significantly reduced, and the sludge treatment processes such as membrane separation, dehydration and incineration are greatly streamlined.

Almost no excess activated sludge is generated from the biological nitrification and denitrification process.

Instead of directly anaerobically digesting human waste and septic tank sludge,
As a result of anaerobic digestion → membrane separation of a mixture of coagulated separation sludge of human waste and concentrated sludge of septic tank sludge, an anaerobic digestion inhibitor (NH ₃ -N, H) present at a high concentration on the liquid side of human waste.
₂ S) does not flow into the anaerobic digester. Therefore, an extremely effective anaerobic digestion reaction proceeds, and organic matter in sludge is thoroughly decomposed.

[Brief description of drawings]

FIG. 1 is a system diagram showing an embodiment of the present invention. 1 ... human waste, 2 ... polymer flocculant, 3,7,23 ... solid-liquid separation device, 4 ... coagulation separation liquid, 5 ... coagulation separation sludge,
6 ... septic tank sludge, 8 ... concentrated separation liquid, 9 ... concentrated sludge, 10 ... anaerobic digestion tank, 11, 16 ... membrane separation device, 12, 17 ... membrane permeate, 13 ... membrane separation Digested sludge, 15 …… Biological nitrification and denitrification process, 18 …… Membrane separation activated sludge, 20 …… Second biological nitrification and denitrification process, 21
…… Coagulant, 22 …… Powdered activated carbon, 24 …… Highly treated water.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display location C02F 3/28 ZAB Z 3/34 ZAB 101 A 11/04 ZAB Z 7824-4D 11/12 ZAB E 7824-4D

Claims (2)

[Claims] 1. A high molecular coagulant is added to human waste to coagulate and separate, and both the coagulated and separated sludge and the concentrated sludge obtained by concentrating and separating the septic tank sludge are subjected to anaerobic digestion and then membrane separated, and the membrane permeate and the above A combined treatment method of human waste and septic tank sludge, which comprises subjecting the aggregated separated liquid of human waste to biological nitrification and denitrification. 2. The combined use of human waste and septic tank sludge according to claim 1, wherein the treated water subjected to the biological nitrification denitrification treatment and the concentrated separation liquid of the septic tank sludge are further subjected to biological nitrification denitrification treatment. Processing method.