JPS58159899A - Treatment of night soil sludge - Google Patents

Abstract

PURPOSE:To subject the sludge in a night soil purifying tank to concn. and volume reduction in a pretreatment to save energy in a final treatment by combining the respective stages of the 1st flocculation and solid-liquid sepn., dehydration, biological treatment, the 2nd flocculation and solid-liquid sepn., flocculation, membrane sepn. and incineration. CONSTITUTION:A flocculating agent is added to the purifying tank sludge collected in a storage tank 1 in the 1st flocculation stage 2 so as to form flocculate. The sludge is separated to the flocculate and sewage with a tilting screen device in the 1st solid- liquid sepn. stage 3; the former is dehydrated with a dehydrator in a dehydration stage 4 and the sewage is fed together with the sewage from the stage 3 to a biological treatment stage 5. The sewage treated bioligically in said stage is treated in the same way as in the stage 2 in the 2nd flocculation stage 6 to form flocculate. The flocculate is settled in the 2nd solid-liquid sepn. stage 7 and is returned to the tank 1, and the supernatant is fed to a flocculation and filtration stage 9. A flocculating agent is mixed with the sewage and the sewage is filtered in said stage; the filtrate is subjeted to a reverse osmosis treatment in a membrane sepn. stage 11 and is separaed to permeated water and concd. water. The latter is treated together with the dehydrated cake from the stage 4 in an incineration stage 12, etc.

Description

[Detailed description of the invention] The present invention relates to a blade and method for treating human waste sludge.

More specifically, the present invention relates to a method for treating human waste sludge containing a large amount of water generated in a human waste septic tank.

Conventionally, human waste sludge generated in human waste septic tanks (hereinafter referred to as human waste septic tank sludge) is generally mixed with human waste and treated by various methods such as aerobic digestion, anaerobic digestion, wet oxidation, and direct incineration. .

Some of it is left alone (1) or mixed with raw human waste and dumped into the ocean.

However, as the amount of human waste septic tank sludge generated has increased in recent years, various problems have arisen in these conventional methods for treating or disposing of sludge.

In other words, when mixing raw human waste and treating it using methods such as incineration, anaerobic digestion, and wet oxidation, it is necessary to mix a larger amount of human waste septic tank sludge, which has a lower concentration than raw human waste. Processing in an even more diluted state has been forced, leading to problems such as a decrease in processing efficiency and an increase in the energy required for processing.

Furthermore, when disposing of waste into the ocean, a problem has arisen in which the amount of waste is increasing.

The present invention was invented in view of the shortcomings of the conventional methods, and its purpose is to pre-treat human waste septic tank sludge to concentrate and reduce its volume.

The object of the present invention is to obtain a method for treating human waste sludge that can save energy in the post-treatment process.

The method for treating human waste sludge according to the present invention that achieves this objective includes a first coagulation step in which a flocculant is added to human waste septic tank sludge to completely form flocs, and a screen made of wire rods with a wedge-shaped cross section is tilted. a first solid-liquid separation step of separating the flocs using a screen device provided;
A dehydration step for completely dewatering the separated flocs from the solid-liquid separation step to obtain a dehydrated cake, a step for biologically treating the wastewater from this dehydration step and the first solid-liquid separation step, and a step for biologically treating the wastewater from this biological treatment step. A second flocculation step in which a flocculant is added to form flocs, and a second solid-liquid separation step in which the flocs formed in the second flocculation step are separated by a screen separation method, a precipitation method, or a pressure flotation method.

A coagulation r-filtration step in which a flocculant is added to the wastewater from this second solid-liquid separation step and the wastewater is filtered, and the rho-filtered water from this coagulation and filtration step is completely treated with a reverse osmosis membrane to obtain concentrated water and permeated water. a membrane separation step, incineration of the concentrated water and the dehydrated cake, anaerobic digestion,
Wet oxidation.

It is equipped with a process of processing or disposing of the waste into one of composting and dumping.
;Hereafter, the first
The present invention will be described in detail based on the flow sheet shown in the figure. Septic tank sludge collected from various septic tanks is stored in a storage tank (1), and the sludge is sent to a first coagulation step (2). In this step (2), a flocculant (2a) is added and mixed, thereby forming flocs in the human waste sludge, making it easy to separate solid and liquid in the subsequent step. In this case, various flocculants, both inorganic and organic, can be used, but a strong thionic polymer flocculant is preferred, and the amount added is preferably 3% by weight or less based on the dry sludge. .

Furthermore, various types of devices such as a stirring tank type, an in-tube mixing type, or an electrolytic flocculation type can be used as the device used for floc formation.

The septic tank sludge in which flocs have been formed in this way is then sent to the first solid-liquid separation step (3), where it is separated into solid and liquid by a screen device provided there.

FIG. 2 shows a schematic configuration of the screen device. Septic tank sludge from the first aggregation step (2) is introduced into a feed box (3a), flows down a screen (3b) provided at an angle, and Here, solid and liquid are separated. The screen (3b) is formed into a flat plate by arranging linear members having a wedge-shaped cross section at equal intervals and in parallel, and the slit width is set to be less than α5M'II. Also, its inclination angle (φ) is 40° to 80° with respect to the horizontal plane.
In addition to the above-mentioned shape, the tail screen (3b) provided in good.

The separated flocs are further concentrated and aggregated on the screen (3b) to form coarse flocs CF), which are sent to the dehydration step (4) and subjected to dehydration treatment. This dehydration process (4
), various conventionally known dewatering devices such as decanters and filter presses can be used.

On the other hand, the wastewater stored in the screen can (3C) of the screen device is sent from there to the biological treatment process (5). At this time, the waste water from the dehydration step (4) is also sent together.

In the biological treatment step (5), treatment is carried out using a contact oxidation treatment tank (5b) which is filled with a net-like contact base material and can be aerated with an aeration pipe (5a). Note that instead of such a catalytic oxidation method, a water sprinkling method, a rotating disk method, an activated sludge method, or the like may be used.

The wastewater biologically treated in this way is then sent to the second coagulation step (6). In this second flocculation step (6), a flocculant (6a) is added and mixed in the same way as in the first flocculation step (2), thereby forming flocs in the wastewater.

Next, the wastewater is sent to a second solid-liquid separation step (7), where flocs in the wastewater are separated by a precipitation method. In other words, % (7a) in the figure shows the settling tank, (7b) shows the supernatant water tank, and the wastewater sent from the second flocculation step (6) to the settling tank (7a) is separated into solid and liquid here, and its wastewater components are separated. is sent to the supernatant water tank (7b), and the sludge components are sent to the storage tank (7b).
1) will be returned to. Note that the solid-liquid separation here may be performed not only by the precipitation method but also by a pressure flotation method, a screen separation method, or the like.

In the case of the screen separation method, as shown in FIG. 3, the second solid-liquid separation step (7) is combined with the first solid-liquid separation step (
It is preferable to arrange a NuClean device similar to the screen device in 3), and to further dispose the entire second dehydration step (8) in series with this.

The wastewater stored in the supernatant water tank (7b) is then sent to the coagulation process (9). At this time, a flocculant (9a) is added, mixed in a mixer (9b), and transferred to an offshore filter (9c).
It is passed offshore. In addition, mixer (9b), offshore filter (9c) f
d Although various conventionally known devices can be used, it is preferable to use a gold film backwash mechanism for the offshore filter (9c). In the figure, (9d) indicates a backwash water supply line, and the washed wastewater discharged from the offshore filter (9c) is sent to the storage tank (1). On the other hand, the Oki persui is sent to the membrane separation process 0υ through the safety filter OG and subjected to reverse osmosis treatment. A reverse osmosis membrane device (lla) is highly pressurized with a pressure pump (not shown).
), the permeate water with extremely low soluble components (llb
) and concentrated water (llc) containing a large amount of soluble components
and Toto are separated. And the concentrated water (l) separated in this way
lc) is further sent to the next incineration step 0shi for treatment.

Further, the dehydrated r-ki (4a) from the dehydration step (4) is also sent to the incineration step (2) for treatment. In the figure.

(12a) shows an incinerator, (12b) shows an ash box, and the incinerator (12a) is provided with a burner (12c).

The exhaust gas generated in this incineration process @ is sent to the deodorizing process (c) via multi-cyclone α3 and cotton tvQ→, where it is treated, and then released into the atmosphere from the chimney αψ. Burner (15b) of deodorizing furnace (15a) and incinerator (12a)
I) Bar + (12c) is supplied with fuel via the heavy oil tank α power and the oil unit (to).

As described above, in the present invention, the raw sludge from the storage tank is first subjected to a flocculation treatment, and then subjected to solid-liquid separation treatment using a screen device, and then the separated flocs obtained thereby are subjected to a dewatering treatment, and then the dewatering treatment and the aforementioned After the wastewater generated in solid-liquid separation treatment is subjected to biological treatment, it is further subjected to coagulation treatment and treated by a total screen separation method, pressure flotation method, or sedimentation method, and the wastewater is coagulated and passed through a reverse osmosis membrane. Since the concentrated water and dehydrated cake are processed and sent to the incineration process, the thermal energy required in the incineration process can be further reduced. In addition, since each of these processing steps is organically combined in a closed channel configuration from the first coagulation step to the deodorizing step, it is possible to prevent the occurrence of pollution and increase the throughput per unit time. .

Furthermore, since multi-stage coagulation treatment and solid-liquid separation treatment are performed as pre-treatments, and further biological treatment and coagulation and overflow treatment are also performed, fouling of the reverse osmosis membrane can be prevented for a longer period of time. In particular, the prevention of contamination caused by soluble organic matter can be greatly improved by biological treatment, and the effect is remarkable. Therefore, the life of the membrane can be further extended.

The treatment is performed using the flow sheet shown in FIG. 1 except for the biological treatment step (5), that is, the wastewater from the first solid-liquid separation step (3) and the wastewater from the dewatering step (4) are directly transferred to the second Table 1 shows the water quality at each deposition when sent to the flocculation step (6) and the amount of permeated water in the membrane separation step αD, and the water quality at each point when treated according to the flow sheet shown in Figure 1. Water quality and membrane separation process αυ
Table 2 shows the amount of water permeated in the test.

Table 1 Table 2 As is clear from this, in the case of treatment excluding biological treatment step (5), the water volume rate of permeated water after 30 days of operation was 40 cm, whereas in the biological treatment step (5)
When all the water is added and treated, the water amount rate is 90 inches, and the rate of decrease is extremely small.

Based on this, if the membrane is to be completely replaced when the water flow rate decreases by 50 to 70 inches, it is expected that treatment will maintain the entire membrane life more than 10 times longer than without biological treatment. be done.

As a result, reverse osmosis can be used economically to treat old septic tank sludge, and after this treatment, only the concentrated liquid and dehydrated cake, whose liquid volume has been reduced to a fraction, need to be completely processed, resulting in energy savings. Aim for it.

Historically, it has been possible to perform all of the dehydration more effectively in the solid-liquid separation process itself, yielding highly concentrated flocs, and reducing the dehydration load in the dehydration process. A□＝
7 pieces IJ -y"A#tD" Form 5K flock from foot box (3a) to screen (3b)
When the raw sludge is fed, most of the water component is removed in the upper region of the screen (3b) and the flocs are separated on the screen surface. The flocs separated in this way are prevented from moving downward by the frictional resistance of the surface in the middle region of the screen (3b), but they aggregate to some extent and become coarser and grow into flocs large enough to overcome the resistance. Then it moves. As the aggregated and coarsened flocs move, the moisture adhering to the floc surfaces is also removed by the screen (3b).

Since the concentrated coarse flocs have a large frictional resistance, they will not move downward unless other flocs gather and become even coarser. By repeating this phenomenon, the flocs gradually grow into higher concentration and coarser aggregates.

In addition, in the lower region of the screen (3b), most of the water adhering to the surface of the aggregated and coarsened flocs is removed, so the sliding frictional resistance of the flocs themselves increases, and therefore the movement speed decreases. , the aggregate of the flocs becomes coarser and coarser, and finally the aggregate of the flocs (F) becomes coarser and has a shape close to a spherical shape.

In this way, in the end, the main phenomenon is rolling down on the screen (3b), and in the process of this rolling phenomenon, the flocs (F) are gradually dehydrated, becoming highly concentrated and dense flocs. It is possible to reduce the dehydration load in the dehydration process.

In addition, in the present invention, the membrane separation step may be provided in a plurality of steps, and the permeated water sent to the outside of the treatment system may be effectively utilized.

If concentration suitable for incineration cannot be achieved with a single membrane separation step, an evaporation concentration step 09 may be provided as shown in FIG.

In the figure, (19a) shows the concentrator, the wire shows all the waste heat boilers,
The evaporation residue (19b) and dehydrated cake (4a) are sent to incineration step 0 for treatment, while the evaporation gas (19c)'! r
Send to deodorizing tank α9 for treatment and waste heat boiler (1)
The steam from the condenser (19a) can be supplied to the concentrator (19a).

In addition, although the embodiment described above is in which the dehydrated cake and concentrated water are incinerated, in the present invention, the dehydrated cake and concentrated water may be mixed and treated by anaerobic digestion, and in addition, wet oxidation or composting may be used. May be processed. Alternatively, it may be disposed of by dumping into the ocean, etc.

As described above, according to the present invention, it is possible to concentrate and reduce the volume of human waste septic tank sludge in the pre-treatment, thereby providing a method for treating human waste sludge that can save energy in the post-treatment.

Furthermore, since biological treatment is performed in the pretreatment, the life of the reverse osmosis membrane can be further extended while treating the human waste sludge.

[Brief explanation of the drawing]

FIGS. 1, 3, and 4 are flow sheets for treating human waste septic tank sludge according to embodiments of the present invention, and FIG. 2 is a schematic diagram of a screen device used in the solid-liquid separation process. (1): Storage tank (2): First agglomeration step (3)
: First solid-liquid separation step (4): Dehydration step (5
): Biological treatment process (6): Second coagulation process (7): Second solid-liquid separation process (9): Coagulation process 0υ: Pus separation process Q2: Incineration process Patent applicant Toshi Engineering Co., Ltd.

Claims (1)

[Claims] (1) A first coagulation step in which a flocculant is added to the septic tank sludge to form flocs, and a first flocculation step in which the flocs are separated by a screen device equipped with an inclined screen made of wire rods with a wedge-shaped cross section. a solid-liquid separation step, a dehydration step of dehydrating the separated flocs from this first solid-liquid separation step to obtain a dehydrated cake, this dehydration step and the first
A step of biologically treating the wastewater from the solid-liquid separation step, a second coagulation step of adding a coagulant to the wastewater from the biological treatment step to form flocs, and screen separation of the flocs formed in the second coagulation step. a second solid-liquid separation step in which separation is performed by a method, a precipitation method, or a pressure flotation method;
A flocculation process in which a flocculant is added to the wastewater from the solid-liquid separation process and the wastewater is filtered, and a membrane separation process in which the wastewater from the coagulation process is treated with a reverse immersion membrane to obtain concentrated water and permeated water. and incineration of the concentrated water and the dehydrated cake, anaerobic digestion, wet oxidation,
A method for treating human waste sludge, comprising a step of treating or disposing of it into one of composting and dumping.