JPS6051595A - Excessive sludge decomposition treatment method and apparatus combined with soil covering type sewage treating apparatus - Google Patents

Abstract

PURPOSE:To perfectly treat excessive sludge, by a relatively simple and small sewage treating apparatus wherein excessive sludge adhered to the pebble layer on a perforated plate is released by forcibly feeding air from an air diffusion pipe provided to the bottom part of a sewage treating tank and decomposed in an aqueous system filter material layer provided the upper part of the tank wall. CONSTITUTION:Sewage is supplied into a sewage treating tank 1 so as to bring the variable surface of sewage to the highest level with respect to excessive sludge adhered to pebbles 3 and, at the same time, air is sent to an air diffusion pipe 6 in an amount of several times as compared with a usual amount to generate a water stream in the tank 1 and the excessive sludge adhered to the pebbles 3 is forcibly released. As a result, a liquid mixture of released sludge and sewage filling the tank 1 is sent into an aqueous system filter material 9 under pressure by a pump P2 through a conduit T and a ceramic pipe 9 provided to the upper part of the tank 1. In this case, moisture is recirculated into the tank 1 from the recessed part of a mountain shaped net 4 and sludge holding a proper amount of moisture remaining in the filter material 9 is subjected to biological decomposition (soil animals, soil microorganisms and plant roots).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for decomposing excess sludge generated from a sewage treatment apparatus.

Conventionally, surplus sludge generated from biological wastewater treatment equipment is subjected to solid-liquid separation, dewatering, drying, and incineration, or is carried out of the system of the wastewater treatment equipment for treatment or disposal.

The smaller the sewage treatment equipment, the more difficult it is to process and dispose of sludge within the treatment plant, so the sludge is transported outside the system.However, in biological treatment, the amount of sludge transported is extremely large due to the high water content. In some cases, sludge treatment was more difficult to maintain and manage. As a countermeasure for this, the amount of surplus sludge generated by the sewage treatment equipment itself is reduced and self-decomposed."
Two methods have been developed by the inventor of the present application (Japanese Patent Publication No. 55
-26929゜5G-23672, 57-4691
9) These methods require separate equipment to treat excess sludge, increasing the site area and construction costs, and in treatment equipment with a small amount of sewage supply, sludge remains attached to the gravel. There were drawbacks.

The present invention has been made to solve the above-mentioned drawbacks.
The purpose is to provide a method and device that can completely treat surplus sludge or use it as liquid fertilizer by simply combining it with sewage treatment maintenance and management work using a relatively simple and small-scale sewage treatment device. It is in.

That is, the present invention introduces sewage into a sewage treatment tank, provides gravel on a perforated plate placed at the bottom of the treatment tank, and interposes sand between the gravel layer and the covering permeable soil. In a sewage treatment method in which the sewage surface is moved downward in a water level variable layer constructed by a water level change layer, and a part of the sewage is infiltrated and discharged from the permeable soil to the outside into the two rings, an aeration pipe is provided at the bottom of the tank, A soil-covered sewage treatment device characterized in that excess sludge adhering to gravel is separated by forced air from an aeration pipe, and the separated sludge is decomposed in a wood-based filter layer provided on the upper part of the tank wall. This is a combined method for decomposing and treating excess sludge.

In addition, a perforated plate is placed at the bottom of the concave sewage treatment tank to form a sewage flow tank at the bottom of the treatment tank, a gravel layer is provided on the perforated plate, and a layer of sand is placed on the top of the gravel layer. In a sewage treatment device constructed by covering permeable soil through a tank, an aeration pipe is provided at the bottom of the tank, and a permeable pipe body is installed at the top of the tank wall,
A wood-based filter medium is installed around the pipe body in a continuous manner with the permeable soil, and excess sludge adhering to the gravel is peeled off by forcing air into the aeration pipe, and the mixed water of this excess sludge and sewage is This is a surplus sludge decomposition device combined with a soil-covered sewage treatment device, characterized in that the surplus sludge is supplied into a pipe.

There are usually two types of surplus sludge generated in biological treatment equipment, but the surplus sludge in the primary treatment equipment (initial settling tank) contains toilet paper and sand and has a slightly lower moisture content, around 97%. Although the surplus sludge in the secondary treatment equipment has a slightly different black rock formation rate between the activated sludge method and the contact bacterium method, the moisture content is still 99%. These two types of surplus sludge differ depending on the size of the equipment, but the former requires maintenance work for several years.
The latter is scheduled to occur between 4 and 48 times a year. The present invention does not require special labor or technology to process surplus sludge, and can be used as liquid fertilizer by simply operating the sewage pump or sludge pump manually or automatically for each of the above-mentioned maintenance operations. be able to.

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a plan view of a device in which an excess sludge decomposition device is combined in permeable soil directly above a soil-covered contact circulation bagging tank, and FIG. 12 is a partial sectional view of this device.

In FIG. 1, sewage is supplied to a sewage treatment tank 1 from a sewage inlet pipe via a sewage mass B. In FIG. 2 is a perforated plate or rosdol having holes for sewage to pass through the soil; 3 is gravel 1; contact wave phase such as synthetic resin or an empty can; 4 is a mountain-shaped mesh. The water level of the wastewater level 5 is varied by changing the electricity supplied to the wastewater. Reference numeral 6 denotes an aeration pipe provided at the bottom of the processing tank 1, to which the air bomb 1 is connected. 7 is covered soil, which usually has a continuous structure of 30 to 50 cm inside and outside the tank.

The above is the structure of a conventional sewage treatment device, but the present invention is designed so that the permeable soil layer 7 is 50 to 80 cm thick, and ceramic tubes 8 are provided with gaps on both sides of the upper side wall of the treatment tank. An appropriate amount of wood filter material 9 is filled around the filter material 9, and the surrounding area of the wood material corrugated layer 9 is covered with net 4' to prevent surrounding soil from being mixed into the filter material 9. The diffuser pipe 6 is one that can forcefully supply air upward. Woody wave phase 9 is a chip.

Crushed wood waste, sawdust, branches, rice husk, peat.

Since the C/N ratio of sludge is low with a mixture of these, it also has the purpose of increasing the C/N ratio to maintain biological activity in the soil. To achieve the same purpose, wheat straw was added to the aerated soil 7.
Contains crushed products such as rice straw, water hyacinth, and fir. The standard C/N ratio in the soil is always in the range of 10 to 15, and if there is a shortage of carbon sources, replenish from the ground surface once every few years.

Next, the operation of the present invention will be explained. Excess sludge generated within the device by supplying sewage into the treatment tank lands on the gravel 3. When the water level of the sewage surface is changed in the sewage treatment tank, the gravel layer is moist, so it does not dry out or form a scum, so sludge does not remain attached to the gravel. However, in small-scale treatment equipment, the amount of sewage supplied may not be large enough to keep moisture in the gravel layer at all times, and sludge may adhere to the gravel and dry out. Therefore, sewage is supplied to the treatment 4 "jlI so that the sewage fluctuation surface is at the highest level, and several times the normal amount of air is supplied to the aeration pipe 6, thereby generating a water flow in the treatment tank and discharging the gravel 3 (= The remaining excess sludge is forcibly peeled off. As a result, a mixed solution of the peeled sludge and sewage fills the treatment tank.

This mixed liquid is supplied into the wood-based filter medium through the conduit T through the ceramic tube 9 in the upper part of the treatment tank by the operation of the sludge transport pump P2. In this case, water flows back into the tank from the concave part of the mountain-shaped ridge 4, and only sludge with an appropriate amount of moisture remains in the woody wave 9 and is biodegraded (soil animals, soil microorganisms, plant roots).
You receive it.

Furthermore, if the end of the ceramic tube 8 is initially returned to the settling tank, it will also be useful for denitrification. In addition, although a 1i-empty ceramic pipe was used in this example, it is not limited to this. For example, it is preferable to connect a ceramic pipe with a large number of permeable holes. Any structure that allows water to pass through is sufficient.

The difference between the present invention and the normal drench method is that the sludge decomposition equipment is used intermittently, once every 15 days or every few months, and because forced aeration is carried out from the lower layer in the permeable soil using an aeration pipe 6. This method creates a soil layer with extremely high biological activity, which promotes the decomposition of sludge.

FIG. 3 shows an embodiment of the pond of the present invention, and is a cross-sectional view of a device in which an excess sludge decomposition device is combined in soil that is continuous with permeable soil outside the soil-covered device. This device is initially used for treating excess sludge in a settling tank, but if it is necessary to simplify the device, use the following methods: The wood wave phase 9 may be omitted. A water-impermeable tank 10 made of a synthetic resin or the like is extended along the side wall of the treatment tank 1. Regarding the specific design, the height of the impermeable tank 10 may be determined by the amount of surplus sludge injected at one time. Coarse sand 11 is spread over the impermeable tank 10.

This coarse sand 11 is heated to 10c so that excess sludge and some water pumped up are filtered out and returned to the treatment 4qlJ.
It is sufficient to install about IIl. 12 is a filter medium similar to 5], and is installed above the coarse sand 11 and around the ceramic tube 13. The ceramic tube 13 is made of 11Y so as to have water permeability.
Sewage is supplied by a sludge transport pump. Half-cut perforated PVC pipes may be used instead of ceramic pipes. The upper part of the filter medium 12 communicates with the permeable soil 15 via the mountain-shaped mesh 14. The overall permeability of the permeable soil 15 is around 60 cm, and the structure in which the permeable soil 15 is continuous with the external soil is a general rule, but it is also possible to implement the structure in which the permeable soil 15 is not continuous. It should be noted that if the end of the ceramic tube 13 is constructed to initially flow back to the inlet of the settling tank, it will also be useful for denitrification, as in the embodiment shown in FIG. In addition, although the sludge decomposition equipment is supplied several times a year, it is preferable to supply an appropriate amount without waiting for the natural generation of earthworms.

FIG. 4 shows another embodiment of the present invention, in which the sludge decomposition device is not brought into contact with the treatment tank in order to utilize the sludge as liquid fertilizer. This case differs from embodiment 97 of FIG. 2 in that coarse sand is not required. The depth of the entire device is about 60 em. Impermeable 4a
16 is typically 20-30 am high, [1''50
It is preferable that it is around coo.

As described above, the present invention is configured so that the sludge decomposition device is used intermittently, once every few months, rather than constantly, so excess sludge can be sufficiently decomposed in Inukimata without a complicated device. , the processing capacity of the sewage treatment tank will be improved. Also, depending on the type of use of agricultural and green space, efficiency may be improved by combining a method in which surplus gas for aeration is injected into the filter medium.

[Brief explanation of the drawing]

FIG. 1 is a plan view of an embodiment of the present invention, FIG. 2 is a partial sectional view of the device shown in FIG. FIG. 1... Treatment tank, 2... Perforated plate, 3... Gravel, 4...
・Ami, 6...Aeration pipe, 7...Aerated soil, Graves...
Ceramic pipe, 9...wood filter material, P2...sludge transport pump. Patent Applicant Niimi Seiji and two other Patent Attorneys Masaru Suzuki Part 4 Figure 1 Toka Hajime

Claims (2)

[Claims] (1) Sewage is introduced into a sewage treatment tank, a gravel layer is provided on a perforated plate placed at the bottom of the treatment tank, and a layer is interposed between the gravel layer and the permeable soil covering it. In the sewage treatment method, a part of the sewage is infiltrated and discharged from the permeable soil into the external soil by moving the sewage surface up and down in a water level fluctuation layer. A decomposition treatment of surplus sludge combined with a soil-covered sewage treatment device characterized by exfoliating sludge by forced air supply from an aeration pipe and decomposing the exfoliated sludge in a wood-based filter layer provided on the upper part of a tank wall. Method. (2) A perforated plate is placed at the bottom of the concave sewage treatment tank to form a sewage flow tank between it and the bottom of the treatment tank, a gravel layer is provided on the perforated plate, and a gravel layer is placed above the gravel layer. In a sewage treatment device constructed by covering permeable soil through a tank, an aeration pipe is provided at the bottom of the tank, and a permeable pipe body is installed at the top of the tank wall,
A wood-based filter medium was installed around the pipe body in continuous contact with the permeable soil, and air was forced to flow through the aeration pipe to cause it to adhere to the gravel. A surplus sludge decomposition device combined with a soil-covered sewage treatment device, characterized in that the surplus sludge is peeled off and a mixed water of the surplus sludge and sewage is supplied into a pipe body.