JP2584392B2 - Undiluted advanced treatment method for night soil and septic tank sludge - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a novel method of purifying organic wastewater such as night soil and septic tank sludge at a remarkably high speed by a unique process, and always obtaining a stable and good advanced treated water. is there.

[0002]

2. Description of the Related Art The most advanced conventional method for treating organic wastewater has a system configuration shown in FIG.
Hereinafter, the urine processing will be described as an example. In this system, human waste sewage 42 is treated and decomposed with ammonia nitrogen components in a nitrification denitrification treatment tank 43, and the nitrification denitrification treatment water is separated into SS in a solid-liquid separation tank 44 provided with a UF membrane (1), and filtered water Was adjusted to pH 4 with NaOH, and an inorganic flocculant (Fe
Cl ₃ solution) is added to coagulate and precipitate the COD component. The precipitate is separated from the SS in a solid-liquid separation tank 45 provided with a UF membrane (2), and the COD component in the filtered water is completely removed by the activated carbon adsorption tower 46. Remove by adsorption. Excess sludge 47 from each step (a part of which is returned to the tank 43 and used for nitrification denitrification treatment) and coagulated sludge 48 are discharged outside the system for treatment. In these treatments, an ultrafiltration membrane (UF membrane) is used as a membrane, and is called a UF membrane separation activated sludge system. But,
As a result of technical evaluation of the latest UF membrane separation method, the following defects were found.

[0003] That is, the required staying days in the undiluted biological nitrification denitrification step require a long time of about 10 to 12 days, so that the construction cost and installation area of the treatment tank are large. The air supply for aeration in this biological denitrification process is large and the aeration power cost is high. The foaming in the biological nitrification and denitrification process is severe, necessitating the addition of an antifoaming agent. A UF membrane is required for each of the two steps of separation of activated sludge and separation of coagulated sludge of advanced treatment, so that the equipment cost of the membrane and the pump power for membrane separation are large. As described above, the UF membrane separation activated sludge treatment known as the latest method in the prior art has many serious drawbacks, and the treatment method is not at all an ideal treatment method for the user. .

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a new system which can completely solve the disadvantages of the conventional system by a new concept. Specifically, 1. Establish a new method that requires only two days in the biological nitrification and denitrification process, and significantly reduce construction costs and installation space. 2. Aeration power for biological treatment is reduced by half
Reduce to １ ／. 3. Bubbling of the biological treatment tank is hardly caused. 4. It is only necessary to apply the UF film in one step. And the cost of membrane construction and the cost of membrane separation power are reduced. The above is an issue.

[0005]

Means for Solving the Problems The teeth of the above objects the present invention
Achieved by an undiluted advanced treatment method for urine and septic tank sludge . That is, the coagulation separation agent is added to night soil and septic tank sludge.
After coagulation and separation, without separating the separated water, at least the fixed bed of the three-dimensional mesh-like granular material in which the denitrifying bacteria are immobilized and the three-dimensional mesh-like granular material in which the nitrifying bacteria are immobilized Water is passed through the aerobic immersion fixed bed in this order.
After adding coagulant or inorganic coagulant and powdered activated carbon, the membrane
Undiluted amount of human waste and septic tank sludge characterized by separation
Achieved by the processing method .

[0006] The present invention is a three-dimensional mesh-like granular material in which SS in organic wastewater such as human wastewater is solid-liquid separated in advance, and the separated water is used as raw separation water to fix nitrifying bacteria and denitrifying bacteria at a high concentration. It has been completed by finding that nitrification and denitrification can be performed at a very high speed by supplying the material to the fixed bed with immersion, the aeration power is small, and there is almost no foaming. Heretofore, there has been no idea of purifying concentrated organic sewage such as night soil undiluted using a immersion biological filter bed of a granular filter medium without dilution. Various means such as coagulation separation, membrane separation and centrifugation can be used as the means for solid-liquid separation.

[0007] As the three-dimensional mesh-like granular material, the porosity of the filter medium is preferably 90% or more. Filter media with large porosity
In addition to being able to carry microorganisms at a high concentration, it has an excellent ability to filter and remove SS components in raw water even when microorganisms are present at a high concentration. Examples of the three-dimensional network granular filter media preferably used in the present invention include, for example, polyurethane foam square granular materials. A polyurethane foam filter medium is produced by foaming a urethane resin by a foaming method for producing open cells, and is cut into a square shape for use. The size of the filter is 10-30m
m, preferably 15 to 20 mm, and the material preferably has a specific gravity of 0.9 to 1.2 and a hole diameter of 2 to 4 mm. The number of holes per 1 cm length is 5-20
Are preferred.

In the present invention, the processing is performed as described above.
Urine and septic tank sludge are separated into solid and liquid in advance, and the separated water is biologically treated in a treatment tank. Hereinafter, three main configuration examples of the processing tank for performing the biological treatment will be described. The fixed bed of the three-dimensional mesh-like granular material on which the denitrifying bacteria are immobilized is referred to as a fixed bed A, and the aerobic immersion fixed bed of the three-dimensional mesh-like granular material on which the nitrifying bacteria are immobilized is referred to as a fixed bed C.

The simplest and functional configuration example is a processing tank having the configuration shown in FIG. 2 and its configuration will be described with reference to FIG. FIG.
In the treatment tank X composed of one tank, a filter medium of three-dimensional mesh-like granular material having microorganisms immobilized on the surface and inside thereof is filled to constitute a fixed bed. An air supply unit 20 is provided at an intermediate portion of the fixed bed. The separated water W from which the organic wastewater SS has been removed (referred to as raw separated water W)
Is supplied from an intermediate portion of the fixed bed, and is caused to flow down in the packed bed in a downward flow. The fixed bed A below the middle part in the fixed bed is filled with denitrifying bacteria immobilized on a filter medium made of three-dimensional mesh-like granular material, and the fixed bed C above the middle part is filled with NH _3.
Nitrifying bacteria for nitrifying -N are immobilized and filled in a filter medium composed of three-dimensional mesh-like granular materials, and both are present at a high concentration.

The gas bubbles containing oxygen, such as air, from the supply unit 20 pass through the fixed bed C to supply oxygen to the nitrifying bacteria. There is almost no dissolved oxygen in the fixed bed A. The denitrified water to be treated is supplied from the bottom of the fixed bed A to the upper part of the treatment tank X via a pipe as outflow water 21. A treated water tank 22 is provided in the middle of the pipe, and the effluent 21 from the bottom of the fixed bed A is temporarily stored in the treated water tank 22 together with the raw separated water W, and a part thereof is circulated as fixed water 23. The upper part of C is supplied by a pump 24. Treated water tank 2
The effluent (final treated water) from the treated water outflow pipe 25 of No. 2 is a mixed water of the circulating water 23 and the raw separation water W added at the intermediate portion of the fixed bed. In the meantime, the final treated water becomes sufficiently clear water. The treated water outflow pipe 25 is an outflow pipe for taking out the final treated water out of the system.

Next, the organic wastewater of the present invention is obtained by vertically dividing a single-tank tank with a partition L (or obtaining the same effect as a two-tank treatment tank installed in close proximity). The configuration of the processing tank Y used for the processing will be described. Here, the configuration of the treatment tank Y will be described with reference to FIG. 3 as a preferable configuration in which the removal of BOD contained in the raw separation water W is enhanced.

The structure for enhancing the removal of BOD is such that a fixed bed B (remaining BOD removal section) is provided between the fixed bed A and the fixed bed C of the treatment tank Y (or a lower part of the fixed bed C). is there. If there is no fixed bed B, a large amount of BOD will flow into the fixed bed C (nitrification section) when the denitrification reaction is deteriorated. This is because it is easy to cause a trouble of changing.

In FIG. 3, a treatment tank Y of the present invention is provided with a fixed bed A and a fixed bed C separated by a partition wall L in the tank, and a grating D in the middle of the fixed bed C to provide a fixed bed. C
The area below the grating D is defined as the fixed floor B. The fixed bed A is filled with a filter medium made of three-dimensional mesh-like granular material and immobilized with denitrifying bacteria, and constitutes an area for performing biological denitrification and filtration of the raw water SS. The fixed bed C is filled with a filter medium made of three-dimensional mesh-like granular material and immobilized with nitrifying bacteria, and constitutes a region where biological nitrification and advanced filtration of SS are performed. Further, the fixed bed B is filled with a filter medium made of three-dimensional mesh-like granular material and immobilized with BOD-utilizing bacteria, and constitutes an area for removing residual BOD and performing advanced filtration of SS.

The raw separated water W flows into the fixed bed A of the treatment tank Y via the raw separated water supply pipe 26, passes through the fixed bed A as a downward flow, and flows from the denitrified water outflow portion 27 thereunder to the fixed bed B. Then, water flows through the fixed bed B as an upward flow, enters the fixed bed C, passes through the fixed bed C, and flows into the fixed bed A again from the circulating nitrification water inflow section 28. A part of the circulating water passing through the fixed bed C as an upward flow flows out of the treated water outflow pipe 29 as treated water 30.

On the upper part of the processing tank Y, there is provided a grating (grid) 31 for covering the upper part of the fixed bed A to prevent the flowing out of the filter medium of the fixed bed A, and for covering the upper part of the fixed bed C. Gratings (lattices) 32 for preventing the outflow of the B-filled filter medium are stretched. Processing tank Y
The lower part of the fixed bed A is provided with an air diffuser 33 for washing the fixed bed A at the lower part, and the lower part of the fixed bed C is used for supplying oxygen to the microorganisms held on the fixed bed C. Are provided. The oxygen-containing gas sent to the air diffuser 34 is sent from the blower 35 via a gas supply pipe 36, and the air diffuser 33 is blown through an air supply pipe 37 to the blower 38.
Supply air from

Further, fixed bed A, fixed bed B and fixed bed C
When cleaning is performed, the cleaning water is supplied from a cleaning water supply pipe 39 above the processing tank Y, and the drainage of the cleaning water is performed from a cleaning drain pipe 40 provided with a valve 41 above the processing tank Y.

According to the configuration of the treatment tank Y, if the denitrification reaction in the denitrification section of the fixed bed A becomes insufficient, and the BOD removal is deteriorated, the remaining BOD removal section E quickly and aerobically. Since the BOD is removed, the BOD does not flow into the nitrification portion (the upper part of the grating D of the fixed bed B), and a great effect that the nitrification reaction is not hindered is produced.

Further, the processing tank Z having one tank is divided into
The configuration of the treatment tank Z used for the treatment of the organic wastewater of the present invention, which is vertically divided by N and N (or the same effect can be obtained as a treatment tank having a three-tank arrangement provided in close proximity), will be described. The configuration of the treatment tank Z is a configuration in which the BOD contained in the raw separation water W is completely removed. Hereinafter, the configuration of the processing tank Z will be described with reference to FIG.

In FIG. 1, a treatment tank Z of the present invention is provided with a fixed bed A, a fixed bed B and a fixed bed C in a tank with a partition wall M and a partition wall N interposed therebetween. The fixed bed A is filled with a filter medium made of three-dimensional mesh-like granular material and immobilized with denitrifying bacteria, and constitutes an area for performing biological denitrification and filtration of the raw water SS. The fixed bed B is filled with a filter medium made of three-dimensional mesh-like granular material and immobilized with BOD-utilizing bacteria, and constitutes an area for removing residual BOD and performing advanced filtration of SS. The fixed bed C is filled with a filter medium made of three-dimensional mesh-like granular material and immobilized with nitrifying bacteria, and constitutes a region where biological nitrification and advanced filtration of SS are performed.

Air diffusion tubes 16, 17 and 18 are provided below fixed beds A, B and C, respectively.
The oxygen-containing gas 7 is constantly supplied from the blower 19 to the air diffusers 17 and 18. At the time of cleaning, the valve V is also opened to increase the amount of the oxygen-containing gas 7 and to diffuse a large amount of gas from the air diffusers 16, 17 and 18 through the fixed beds A, B and C, respectively.
Insufflate and flush.

The raw separated water W flows into the fixed bed A of the treatment tank Z, and flows through the fixed bed A in a downward flow together with the circulating nitrified water 6 also flowing from above the fixed bed A to anaerobically denitrify. After the reaction, the fixed bed B enters the fixed bed B from the denitrified water outflow portion 4 below the fixed bed A, and the fixed bed B is passed as an upward flow to aerobically remove the BOD component in the denitrified water. The fixed bed C enters the fixed bed C as the outflow water 8 from the upper part and flows through the fixed bed C as a downward flow, and the nitrification reaction is performed aerobically in the fixed bed C to nitrify the ammonia nitrogen component. A part of the effluent 9 from the lower part of the fixed bed C flows into the fixed bed A again as the circulating nitrified water 6, where the ammonia nitrogen component becomes nitrogen gas and is discharged out of the system. A part of the circulating water that has passed through the fixed bed C as an upward flow is treated with a coagulant in the next step, and flows out as a treated water 14 from a treated water outlet pipe through a membrane separation step 13.

According to the present invention, as a filter medium to be filled in a fixed bed, a filter medium made of a three-dimensional mesh-like granular material is specified and used. 5 times)
It is important to fix the BOD and to provide a residual BOD removal part between the denitrification area and the nitrification area. (Operation) An embodiment of the present invention will be described with reference to FIG. However, the present invention is not limited by the following description. After adding a cationic or amphoteric polymer flocculant 3 to the organic sewage 1 to form a coarse floc, the solid-liquid separation was performed using a wedge wire screen provided in the solid-liquid separation section 2 to obtain an SS content of 100 mg. / Liter or less of clear separation water W is obtained. Although the centrifugal separation method may be used as the solid-liquid separation means, the power required is small and the SS removal rate is higher in the coagulation separation method. Separated sludge 5 is discharged from the solid-liquid separation unit and dewatered by a dehydrator (not shown) such as a screw press.

Separated water W from the solid-liquid separation section 2 first flows into the upper part of a fixed bed A, which is a submerged biological filter bed filled with a three-dimensional mesh-like granular filter medium immobilized with denitrifying bacteria, which will be described later. It flows down in the fixed bed A in a downward flow together with the circulating nitrified water 6 from the fixed bed C, and is denitrified at high speed in the process.

The effluent from the fixed bed A is aerobic because residual SS is removed, BOD and NO _x -N are reduced, and the water quality is high including NH ₃ -N. BOD-utilizing bacteria are supplied to the fixed bed B immobilized on the surface and inside of the three-dimensional mesh-shaped granular filter medium for removal, and the treated water is contacted while aerated with an oxygen-containing gas. As a result, the effluent 8 from the fixed bed B has a BOD of 10 mg / liter or less.

Next, the effluent water 8 is supplied to a fixed bed C filled with a three-dimensional mesh-like granular filter medium in which nitrifying bacteria are immobilized at a high concentration.
/ Liter · hour), the NH ₃ -N is nitrified into NO _x -N. (Some nitrification may progress on fixed bed B.)

Thus, a fixed bed C on which nitrifying bacteria are immobilized
A part of the effluent 9 from the wastewater is refluxed to the fixed bed A as the circulating nitrification water 6, and the remaining effluent is added with an inorganic condensing agent 11 such as FeCl ₃ or the like and powdered activated carbon 12, and the UF or MF membrane is used. When separated, SS, BOD, COD,
The treated water 14 from which all of chromaticity, phosphorus, and total nitrogen are highly removed is obtained. The coagulated and separated sludge 15 separated from the membrane separation step 13 is discharged and solid-liquid separated together with the organic wastewater 1.

When removal of COD and color is not required, the addition of the inorganic condensing agent 11 and the powdered activated carbon 12 and the membrane separation step 13 can be omitted, and the treated water 9 from the fixed bed C can be discharged water. . In such a case, the BOD, SS, and TN (total nitrogen) of human waste are removed and discharged into a sewer pipe. Also, the membrane separation step 13
Any of a tubular type and a hollow fiber type membrane module may be applied.

In the present invention, it is particularly noted that
Foaming is hardly observed on the water surface of the biological treatment tank Z (the tank including the whole of the fixed beds A, B, and C). As a result of examining the cause, nitrifying bacteria, denitrifying bacteria, and BOD assimilating bacteria were found. The microorganisms which are fixed on the three-dimensional mesh-like granular filter medium and are suspended in the water are 1/100 of those of the conventional activated sludge method.
It was found that the foam stabilization effect was small and the bubbles were easily removed. In addition, the type of the nitrification reaction of the present invention is usually NO ₂ -N type, and as a result, aeration power can be reduced, which is preferable.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Human waste 1 according to the flow of the present invention shown in FIG.
Processing was performed on a kiloliter / day scale. Hereinafter, embodiments of the process of the present invention will be described with reference to this mode of the process, but this description does not limit the present invention.

(Example 1) Configuration of Apparatus The coagulation separation screen used in the solid-liquid separation section 2 is an inclined wedge wire screen having an aperture of 1 mm. Circulation ratio of circulating nitrified water 6 refluxing from fixed bed C to fixed bed A: 15 times Filter media to be filled in fixed bed: 10 × 25 × 25 mm square polyurethane foam Membrane separation device: MF hollow fiber membrane module with pore diameter of 0.1 μm Operating conditions of equipment Number of days of raw water staying days Number of days staying in denitrification section (fixed bed A) 0.7 days Number of days staying in residual BOD removal section (fixed bed B) 0.3 days Staying in nitrification section (fixed bed C) Number of days 1.0 days Total staying days 2.0 days Injection amount of inorganic coagulant for advanced treatment FeCl ₃ 2500 mg / L NaOH (addition required to adjust to pH 4) Amount) Injected amount of powdered activated carbon 500 mg / liter A continuous operation for 6 months was performed under the apparatus configuration and operating conditions of at least, and as a result, highly treated water having the water quality shown in Table 1 was obtained.

[0031]

[Table 1]

The fixed beds A, B, and C can be easily washed by increasing the amount of air in the air diffusers 16, 17, and 18 and performing vigorous air washing. The SS discharged by the washing is subjected to membrane separation. Separated in step 13. It was confirmed that urine containing high concentration of pollutants as shown in Table 1 could be converted into highly purified treated water in a few days of stay.

[0033]

According to the present invention, the following extremely excellent effects can be obtained, and the drawbacks of the UF membrane separation activated sludge treatment known as the latest method in the prior art can be completely overcome. 1) The required area of the processing device is about 1/5 to 1
/ 6, making it possible to significantly reduce the construction ratio and save space. 2) The power required for aeration of biological treatment (nitrification section and BOD removal section) can be reduced to 1/3 of conventional power. In the conventional method, it is necessary to aerate about 900 Nm ³ of air per kiloliter of human waste, but in the method of the present invention, it is sufficient to supply about 300 Nm ³ of air per kiloliter of human waste. This is considered to be because the time for air bubbles to pass between the filter media of the filter bed filled with the polyurethane foam filter media is long, and the oxygen absorption rate is improved. 3) The surprising effect of almost no foaming of the water to be treated in the biological treatment tank is obtained (one of the biggest problems of the conventional method is the vigorous foaming of the water to be treated in the biological treatment tank). 4) Since only one stage of the membrane treatment process is required (the membrane only needs to be installed in the advanced treatment part), the equipment cost and the running cost of the membrane treatment are reduced to half. 5) No granular activated carbon adsorption tower is required.

[Brief description of the drawings]

FIG. 1 is a flowchart of an organic sewage treatment using a treatment tank including a fixed bed holding BOD-utilizing bacteria of the present invention.

FIG. 2 is a flow chart of an organic wastewater treatment using a treatment tank having the simplest fixed-bed configuration of the present invention.

FIG. 3 is a flowchart of an organic sewage treatment using another treatment tank having a configuration including a fixed bed holding BOD-utilizing bacteria of the present invention.

FIG. 4 is a flow chart of human wastewater treatment using the latest conventional UF membrane separation activated sludge method.

[Explanation of symbols]

Reference Signs List 1 human wastewater 27 denitrified water outflow section 2 solid-liquid separation section 28 circulating nitrification water inflow section 3 polymer flocculant 29 treated water outflow pipe 4 outflow water (1) 30 treated water 5 separated sludge 31 grating 6 circulating nitrified water 32 Grating 7 Oxygen-containing gas 33 Empty washing diffuser tube 8 Outflow water (2) 34 Aerator tube 9 Outflow water (3) 35 Blower 11 Inorganic coagulant 36 Gas supply tube 12 Powdered activated carbon 37 Air supply tube 13 Membrane separation process 38 Blower 14 Treatment Water 39 Cleaning water supply pipe 15 Coagulated and separated sludge 40 Cleaning drainage pipe 16 Diffusion pipe 41 Valve 17 Diffusion pipe 42 Night soil 18 Diffusion pipe 43 Nitrification denitrification tank 19 Blower 44 Solid-liquid separation tank 20 Air supply unit 45 Solid-liquid separation tank Reference Signs List 21 effluent 46 activated carbon adsorption tower 22 treatment tank 47 excess sludge 23 circulating water 48 coagulated sludge 24 circulation pump 49 return sludge 2 Treated water outlet pipe A fixed bed 26 separating water supply pipe B fixed bed C fixed bed D grating in the partition M in L partition N in dividers V valve W original separated water X treatment tank Y processing tank Z biological treatment tank

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical indication location C02F 11/00 C02F 11/00 B 11/02 11/02 (56) References JP-A-2-2 43998 (JP, A) JP-A-3-123698 (JP, A) JP-A-3-90696 (JP, U)

Claims (1)

(57) [Claims] 1. An aggregating and separating agent is added to night soil and septic tank sludge.
After coagulation and separation, without separating the separated water, at least the fixed bed of the three-dimensional mesh-like granular material in which the denitrifying bacteria are immobilized and the three-dimensional mesh-like granular material in which the nitrifying bacteria are immobilized Water is passed through the aerobic immersion fixed bed in this order.
After adding coagulant or inorganic coagulant and powdered activated carbon, the membrane
Undiluted amount of human waste and septic tank sludge characterized by separation
Degree processing method .