JPH01315355A - Treatment of septic tank sludge - Google Patents

Abstract

PURPOSE:To make it possible to effectively separate suspended matter, slime and sediment in septic tank sludge by cutting and crushing the suspended matter in the sludge with a high pressure jet of water. CONSTITUTION:Raw sludge 30 thrown on a conveyor 20 is exposed to a high pressure jet 23 of water from a nozzle 21 to cut and crush suspended matter such as fibers in the sludge 30. The pressure and speed of the jet 23 are selected so as to cut and crush the suspended matter without cutting or crushing sediment such as cans in the sludge 30. The sludge 30 is then put in a washing and separating vessel 10 contg. washing water and this water is circulated by agitation with air from nozzles 13 to wash the sludge 30. The suspended matter, slime and sediment in the sludge are effectively separated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for washing and separating sludge collected in urban sewers, rivers, etc.

[Prior art] Sludge contains plastics, paper, wood chips, and miscellaneous materials, and is collected at pumping stations and settling ponds for urban sewage, and contains the above-mentioned sludge. In addition to food, there are large amounts of human excrement, cans, bottles, hardware, etc. Furthermore, it had a large amount of sludge attached to it, giving off a foul odor and rotting, making it impossible to dispose of it by landfilling or incinerating it. Therefore, these residues are washed with water to remove floating materials (plastics, paper, wood chips, cloth, etc.) and sediments (
Cans, bottles, hardware, etc.) and sludge are separated from the sludge, the floating material is collected again, dehydrated, and then landfilled or incinerated.Sediment is collected, and the sludge is returned to, for example, a settling pond along with the washing water. was taken.

However, in recent years, there has been a demand for higher performance and labor savings in sewage treatment plants and the like, and various attempts have been made to treat sludge as part of this.

The factor that prevents high performance and labor-saving in conventional sludge processing is that, as mentioned above, sludge is contaminated with miscellaneous substances, and these must be washed and separated together. 1) Fibrous strings, cloth, and plastics get tangled with equipment during cleaning, and must be removed frequently6. 2) The above-mentioned items also get tangled with each other during cleaning and become lump-like. This will eventually impair the cleaning effect.

3) Solid substances such as human excrement are carried by the water flow during washing and simply float on the water surface, hardly being dissolved in the washing water, and are eventually collected together with the scum. As a result, the original purpose of separation is not achieved.

7 Therefore, as a measure to improve the performance and save labor in processing these residues, a method has been proposed in which the residue is crushed in a crusher and then washed and separated. The crusher used a rotary or guillotine-type cutter to shear and crush the residue.7 By crushing and washing and separating the residue, it is possible to prevent the residue from getting entangled with equipment, and it is also effective in cleaning. Furthermore, solid matter such as human excrement is crushed and easily suspended in the washing water, and can be easily separated from floating matter.

In addition, as another means for crushing dust similar to scum, Japanese Patent Laid-Open No. 60-82151 discloses a method using high-pressure water jets. In order to do this, it is said that anything in the garbage will be finely pulverized.

[Problems to be Solved by the Invention] However, the following problems occur in the method of crushing the ground residue using a mechanical crusher as described above and then washing and separating it.

b) Since miscellaneous things are mixed in the liquid as mentioned above, wear and tear on the cutter cannot be avoided.
It must be maintained and inspected frequently.

A) Hardware, cans, and bottles are crushed into small pieces, which makes them difficult to settle, especially in flowing water, and they are collected together with suspended matter, defeating the purpose of cleaning and separation. I can't reach it.

c) In particular, when cans and hardware are crushed, sharp edges and cracks are formed due to shearing, and these trap floating substances during crushing and cleaning, resulting in poor cleaning and separation effects.

That's what it was.

Also disclosed in Japanese Patent Application Laid-Open No. 60-82151,
The purpose and effect of shredding dust using high-pressure jet water is to finely shred any substances contained in the dust, so this method can be applied to washing and separating residue. However, the above-mentioned problems in item (a) and c) still remain unsolved.

[Means for Solving the Problems] The present invention provides a method for treating persimmon residue, in which the persimmon residue is cut and crushed by a high-pressure water jet, and at this time, the relative running speed of the residue is set to 30 CIl/min or more, and the high-pressure The pressure of the water jet was set to 3000 kg/cm2 or less to cut and crush floating materials such as fibers, plastics, and paper, and to avoid cutting and crushing settled metal objects, cans, and bottles, and then rinsed them with water. The liquid is poured into a washing tank and washed using water flow caused by mechanical or air agitation to separate suspended matter, sludge, and sediment in the liquid.

[Function] By cutting and crushing the residue with a high-pressure water jet, it is possible to prevent wear and tear on the cutter that is required in conventional mechanical crushers, and it is also possible to wash the sediments, such as metal objects, cans, and bottles, without cutting and crushing them. Therefore, they easily settle and do not entangle floating substances, making it possible to further enhance the cleaning and separation effects. Furthermore, if the residue is loosened with a pressure water jet after or at the same time as cutting and crushing with a high-pressure water jet, the subsequent cleaning effect can be further enhanced. This has the advantage that part of the sludge is washed away and the load on the cleaning tank can be reduced.

If a step of rolling the residue to a predetermined thickness is added before the above-mentioned cutting and crushing using the high-pressure water jet, the sediment will be crushed and will settle more easily, and the suspended matter will be compressed into a flat plate. This makes the thickness relatively uniform, and since it is cut and crushed, the pressure of the high-pressure water jet can be set low, and control becomes easy.

[Example] Embodiments of the present invention will be described in detail based on the drawings.

FIG. 1 is an explanatory diagram showing the steps of the method for treating scum of the present invention. First, the residue collected by a screen in a sand settling area is temporarily stored, then quantitatively discharged, and as described later, is cut and crushed using a high-pressure water jet while being conveyed by conveyor means such as a conveyor. The cut and crushed residue is put into a washing tank as described below, and the floating matter, sediment, and sludge in the solution are liberated by stirring and flowing washing water, and then suspended by specific gravity. The solids and sediment are separated, and the sludge is suspended in the wash water and discharged together with the wash water. FIG. 2 is an explanatory diagram showing the entire structure of the eliminator treatment device, and FIG. 7 is a view taken along the line A--A in FIG. 2. In the figure, 1 is a washing and separating device, and 2 is a cutting and crushing device. The washing and separation apparatus 1 has a chain 11 with flights rotatably suspended in a washing and separation tank 10, and is driven by sprocket wheels 121 to 128.

Further, the cleaning separation tank 10 is provided with air nozzles 13, 14, a settling plate 15, a partition plate 16, a floating matter scraping plate 17, and a cleaning water outlet 18, respectively. The cutting and crushing device 2 includes a conveyor 20, a high pressure water jet nozzle 21 and a high pressure water pump 22 disposed above the conveyor 20.

The positional relationship between the conveyor 20 and the high-pressure water jet nozzle 21 is as shown in FIG. That is.

The conveyor 20 has a plurality of chains 201 arranged in parallel, a pan 202 made of steel plate is attached to this, and a high-pressure water jet nozzle 21 is arranged directly above the gap 203 of each pan 202.
High pressure water jet 23 is allowed to pass through gap 203. In this embodiment, the high-pressure water jet nozzles 21 were arranged in a line perpendicular to the traveling direction of the conveyor 20, and the arrangement pitch was 200 m. However, the smaller the arrangement pitch, the smaller the cut and crushed residue becomes, and the greater the cleaning effect in the cleaning process or the effect of preventing it from getting tangled with equipment. Since the power of the high-pressure water pump increases, it is necessary to select the arrangement pitch by taking into account both the required cutting and crushing size of the residue and the power.

The high-pressure water jet nozzle 21 and the high-pressure water pump 22 are connected by a high-pressure pipe 27. Plunger pumps are usually used as high-pressure water pumps.

If an ultra-high pressure water jet of 3000 kg/crn2 or higher is required, a hydraulic cylinder type booster may be added.

Next, the effect will be explained.

First, the residue collected by a screen (not shown) in a settling basin is stored in a storage tank (not shown).

This is dispensed quantitatively as appropriate, and conveyed to conveyor 2.
Drop onto 0. Raw residue 3 dropped onto the conveyor 20
0 is cut and crushed by a high-pressure water jet 23 sprayed from a high-pressure water jet nozzle 21 while being transported.

What is important at this time is that the fibers, plastics, paper, etc. floating in the stock solution are cut and crushed by a high-pressure water jet.
The purpose is to prevent metal objects, cans, bottles, etc. that are sediment from being cut and crushed. Therefore, the inventor proposed that by adjusting the pressure of the high-pressure water jet and the relative traveling speed of the slag and the high-pressure water jet (in this embodiment, this is the traveling speed of the conveyor 20), the suspended matter is cut and crushed, and the sediment is removed. We conducted experiments to explore the range in which the material would not be cut or crushed. The results are shown in Table 1. In this experiment, a high-pressure water jet nozzle was used, the tooth gap to the residue was 40 mm, and the pressure was measured between the high-pressure water pump and the high-pressure water jet nozzle. In addition, cans and hardware are exposed to the top surface of floating objects, and if cans and hardware are hidden in floating objects, they may be partially or almost completely cut and crushed. From Table 1, it can be easily inferred that the range swings toward the higher pressure side and the lower speed side.

As shown in Table 1, the pressure of the high pressure water jet is 300
0 kg/cm" and the relative traveling speed was 10 cmZ, two cans were partially cut and crushed, and the floating matter was cut and crushed without any problems.Furthermore, the pressure of the high-pressure water jet was reduced, and the relative traveling speed was reduced. When the value was increased, floating objects could be completely cut and crushed, but cans were not cut or crushed at all.

Therefore, when cutting and crushing the residue according to the present invention,
When the relative speed is 30 cwI/min or more, the pressure is 3000/
It is preferable to carry out the process under conditions of C112 or lower.

Next, in order to confirm the effect of cutting and crushing the residue according to the present invention, an experiment was conducted on the material balance due to crushing.

Table 1 ○: Completely cut and crushedΔ: Partially cut and crushed Spread it out, crush it with a high-pressure water jet, and collect as much as possible of the residue remaining on the net conveyor (hereinafter referred to as crushed residue) and the residue, sludge, etc. that passed through the net conveyor (hereinafter referred to as crushing effluent), and The weight of each of the residue, crushed residue, and crushed effluent was measured. Furthermore, the weight of the high-pressure water introduced was subtracted from the weight of the crushing effluent to determine the weight of the fine residue in the crushing effluent to obtain Table 2. Fine residue includes not only fine residue but also human excrement, sludge, etc. that have been crushed into a slurry form.

From the same table, the total weight of the raw residue at the time of collection is approximately 80% of that at the time of input, and the total weight of the raw residue is about 2.
It was separated into crushed residue of 7-41% and fine residue of 40-54%. As a result, even if all the unrecovered components were crushed and added to the residue, the proportion of crushed residue would be 46 to 60%, which means that even if we estimate it on the high side, the weight is reduced to about 60% compared to the original residue. This is what is sent to the washing process, which is a subsequent process. In other words, a considerable amount of the sludge and the like that should be washed away in the washing process is washed away by the high-pressure water jet in the process of crushing the original residue. As will be described later, this naturally reduces the load on the cleaning process. It is clear that such a reduction in the amount of residue cannot be achieved with a mechanical crusher. In addition, the crushing effluent is in the form of a slurry and will not cause any problems even if it is sent to a post-treatment process.

Table 2 shows an example when factors other than pressure are fixed.1 For example, if the crushing speed, that is, the relative movement speed between the high-pressure water jet and the raw material, and the interval between the high-pressure water jets are changed,
It is possible to change the weight loss rate by as much as 40%.

Next, the droplet group 30 cut and crushed by a high-pressure water jet is dropped into the cleaning separation tank 10, and air is injected from the air nozzle 13 to stir and flow the cleaning water, thereby cleaning the residue. Floating matter, sludge, and settled matter in the liquid are separated, and the floating matter is scraped up on the washing water surface by the flighted chain 11 to the right in FIG. 2 and lifted up on the floating matter scraping plate 17. The sludge is suspended in the wash water and discharged from the wash water outlet 18 together with the wash water.The sediment settles and slides down on the settling plate 15 to the wash separation tank. 10
This is also discharged by the flighted chain 11 as shown by the arrow.

An experiment was also conducted to confirm the effectiveness of this cleaning.

In other words, the crushed residue remaining on the net conveyor after injection of high-pressure water jet is 5 times, 12.5 times, and 25 times
Rinse with twice the amount of washing water, measure the COD after washing, and compare the COD of the raw material residue and the COD when the raw material residue is washed with 5 times, 12.5 times, and 25 times the amount of washing water. were also measured and compared, Figure 8 was obtained. COD is JIS
K-0102 Accordingly, the amount of oxygen consumed by potassium permanganate at 100°C was measured and calculated by converting it into dry unit weight. The COD in Figure 8 shows the COD still attached to each residue after washing, and the smaller this value is, the better. It shows the ratio of COD removed from each scum during washing to COD, and naturally the larger the value, the better.

From FIG. 8, it can be seen that when the raw material residue is crushed and then washed according to the present invention, the COD is reduced and the COD removal rate is improved than when the raw material residue is washed as it is7. The magnification of the washing water when washing after crushing, 5 times, 12.5 times, and 25 times, is the magnification of the crushed residue, and the crushed residue has a weight ratio relative to the original residue as described above. Although the amount of washing water has been reduced to 60%, if the magnification of the washing water is shown relative to the original residue, it will be 3 times, 7.5 times, and 15 times, respectively. The dotted line shows the equivalent conversion to the value for COD and COD removal rate of the residue crushed by high-pressure water jet,
The relationship with the simple washing water amount magnification is on the dotted line and its extension. As is clear from the same dotted line, when crushing and cleaning according to the present invention, in addition to the improved cleaning effect, the weight reduction due to crushing is synergistic, and the cleaning load is reduced. The present invention has a high cleaning effect, but at the same time, metal objects, cans, and bottles that are sediments in the solution are not cut and crushed.
Since it remains as it is, it can settle quickly, and cans and bottles in particular settle when water is poured into them while they are being stirred, get entangled with floating substances, and are discharged together with the floating substances. There was no such thing.

FIG. 3 is an explanatory diagram showing the steps of another embodiment of the present invention. To explain only the different parts from the method explained in Figure 1,
Before transferring the residue to the conveying means, it is rolled into a flat plate using a rolling means such as a rotary press as described later, and then cut and crushed using a high-pressure water jet. FIG. 4 is an explanatory diagram of the configuration of an apparatus according to an embodiment of the present invention. Description of parts that overlap with FIG. 2 will be omitted. In FIG. 4, 24 is a rotary press. Before cutting and crushing the droplets using a high-pressure water jet, the press 24 rolls them to a predetermined thickness and crushes the cans and bottles contained therein to make them easier to settle. Since the group is made into a flat plate shape, the cutting and crushing effect of the high-pressure water jet is increased.6 FIG. 5 is an explanatory diagram showing the steps of another embodiment of the present invention. To explain only the different parts from the method explained in Figure 1,
The residue that has been cut and crushed with a high-pressure water jet is further loosened with a high-pressure water jet, and then washed. FIG. 6 is an explanatory diagram of the configuration of an apparatus according to another embodiment of the present invention.

Description of parts that overlap with FIG. 2 will be omitted. In FIG. 6, 25 is a pressure water jet nozzle, and 26 is a pressure water jet. By rotating this pressure water jet 26 with a known horizontal rotation means and slowly loosening the entire surface of the droplets that have been cut and crushed by the high-pressure water jet, the subsequent cleaning effect can be further enhanced6. The water jet also has the effect of washing away some of the sludge adhering to the droplet group, which can reduce the subsequent load on the cleaning tank. Note that the wastewater containing sludge from the pressure water jet may be returned to the settling basin.

Furthermore, in the above-described embodiment, a plurality of high-pressure water jet nozzles 21 are arranged in a line in a direction perpendicular to the traveling direction of the conveyor 20, but when cutting and crushing a thicker layer of droplets, a plurality of Furthermore, in the above-described embodiment, the high-pressure water jet nozzles 21 are fixed and the droplets on the conveyor 20 are moved.
The droplets are cut and crushed into strips, some of which may be relatively large pieces. If provided, it is also possible to cut and crush droplet groups into basic grid shapes.

Furthermore, instead of the washing and separation apparatus described in the above-mentioned embodiments, a washing and separation apparatus equipped with stirring blades and a screen may be used. You can expect similar effects.

・Suspended matter, sludge, and sediment in the liquid can be effectively separated by crushing.

- As a result, the amount of residue to be cleaned can be reduced to 60% by weight.

- Since the residue is cut and crushed for cleaning, the cleaning effect is enhanced, and since the residue that is the target of the cleaning is reduced in volume, the cleaning effect of the entire device is further increased.

・Maintenance and inspection are easy because it prevents entanglement with equipment, reduces wear and tear, and reduces failure.7

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the steps in the embodiment of the present invention, FIG. 2 is an explanatory diagram of the configuration of the apparatus in the embodiment of the present invention, and FIG.
The figure is an explanatory diagram showing the steps in another embodiment of the present invention, FIG. 4 is an explanatory diagram of the configuration of the apparatus in another embodiment of the present invention,
FIG. 5 is an explanatory diagram of the process in another embodiment, FIG. 6 is an explanatory diagram of the apparatus in another embodiment, and FIG.
6 and 8 are explanatory diagrams showing the cleaning effect.

Claims (1)

[Scope of Claims] 1) The residue is cut and crushed by a high-pressure water jet whose pressure and running speed are selected so as not to cut and crush suspended matter such as fibers therein, and to avoid cutting and crushing sediments such as cans. , followed by washing to separate floating matter, sludge, and sediment. 2) Roll the residue to a predetermined thickness, cut and crush floating substances such as fibers, and cut and crush sediments such as cans with a high-pressure water jet whose pressure and running speed are selected so as not to cut and crush the residue. ,
A method for treating sludge, which comprises washing and separating floating matter, sludge, and sediment. 3) The residue is cut and crushed by a high-pressure water jet whose pressure and running speed are selected so as not to cut and crush the floating matter such as fibers, and to avoid cutting and crushing the settled matter such as cans. A method for treating sludge, which comprises loosening the sludge, followed by washing to separate floating matter, sludge, and sediment. 4) Roll the residue to a predetermined thickness, cut and crush floating substances such as fibers, and cut and crush sediments such as cans with a high-pressure water jet whose pressure and running speed are selected so as not to cut and crush the residue. ,
Loosen it with a jet of pressure water, then wash it,
A method for treating sludge, characterized by separating floating matter, sludge, and sediment. 5) The residue is cut and crushed using a high-pressure water jet with a relative running speed of 30 cm/min or more and a pressure of 3000 kg/cm^2 or less, and then washed to separate floating matter, sludge, and sediment. Characteristic method of processing residue.