JPH0663585A - Waste water treatment device - Google Patents

Abstract

PURPOSE:To satisfy the water quality standard of waste water and to decrease the amt. of the sludge to be generated. CONSTITUTION:This waste water treatment device is constituted by providing a first settling tank 9 and a second settling tank 14, providing a filter medium washing type filter device 11 next to this first settling tank 9 and returning the sewage contg. the sludge after washing of filter sand discharged from this filter medium washing type filter device 11 into a raw water tank 2 via a piping 13. Then, the supernatant water of the treated water subjected to the sedimentation and sepn. of the sludge in the first settling tank 9 is sufficiently filtered by the filter medium washing type filter device 11. The sewage contg. the sludge discharged from the filter medium washing type filter device 11 is supplied again from the raw water tank 21 to an anaeration tank 4 and an aeration tank 7 where the sewage is subjected to anaeration treatment and aeration treatment and is decomposed to gaseous methane, carbon dioxide, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waste water treatment apparatus suitable for purifying industrial waste water containing organic substances.

[0002]

2. Description of the Related Art Generally, a wastewater treatment device for purifying factory wastewater containing organic substances emitted from food factories is a raw water tank for storing the factory wastewater as raw water and a contaminant removal screen for removing contaminants in the raw water. And an anaerobic tank for decomposing organic matter in the raw water flowing from the raw water tank into methane gas, carbon dioxide gas and sludge using anaerobic bacteria, and a treatment provided at the next stage of the anaerobic tank and flowing in from the anaerobic tank Aeration tank that decomposes residual organic matter in water into sludge and carbon dioxide while supplying air to activated sludge, and separates sludge in treated water that has been decomposed by the anaerobic tank and the aeration tank. It is widely known that a sedimentation tank that discharges the supernatant water and a dehydration treatment apparatus that dehydrates sludge that has settled in the sedimentation tank are roughly constituted.

Next, the operation of the waste water treatment equipment constructed as described above will be explained.

First, when factory wastewater containing organic substances is discharged, this wastewater (raw water) flows into a raw water tank through a pipe and is temporarily stored in the raw water tank. At this time, it is relatively large. The contaminants are removed by a contaminant removal screen. Next, the raw water is pumped up through a pipe or the like and flows into the anaerobic tank, where the organic substances are decomposed by anaerobic bacteria into methane gas, carbon dioxide gas and sludge. Here, the methane gas generated in the anaerobic tank is recovered by a methane gas recovery device and used as a fuel for keeping the anaerobic tank in a predetermined temperature range to activate anaerobic bacteria.

Then, the treated water decomposed in the anaerobic tank flows into the aeration tank through a pipe, and the remaining organic substances which have not been decomposed by the anaerobic treatment in the aeration tank are activated. Sludge is decomposed into sludge and carbon dioxide. Next, the treated water re-decomposed by aerobic treatment is supplied to a settling tank, and the sludge is naturally settled and separated in the settling tank. Then, when the sludge settling in the settling tank is completed, only the supernatant water of the purified treated water is discharged through a discharge valve or the like, and the sludge settling in the settling tank is dehydrated by a dewatering device. After that, it is disposed of as industrial waste.

[0006]

By the way, in the wastewater treatment equipment according to the above-mentioned prior art, the anaerobic treatment in the sedimentation tank,
Although only the supernatant water of the treated water is released by precipitating the organic matter sludged by aerobic treatment, it is difficult to completely settle the sludge in the settling tank, and the operating conditions of the factory If the amount of wastewater discharged from factories increases sharply due to factors such as anaerobic treatment and aerobic treatment, organic matter in raw water cannot be decomposed sufficiently, and sludge or anaerobic treatment is required in the discharged water (supernatant water). However, there is a problem that organic substances, etc. that could not be completely decomposed by aerobic treatment may be mixed in and the water quality standard of wastewater cannot be satisfied.

Further, in the wastewater treatment equipment, all sludge settled in the settling tank is dehydrated by the dehydration treatment equipment and disposed of, so that the amount of sludge to be disposed of increases, and the disposal treatment fee and There is a problem that the labor cost related to the disposal work increases and the cost greatly increases.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to provide a wastewater treatment apparatus which satisfies the water quality standard of wastewater and can reduce the amount of sludge to be discarded. To do.

[0009]

In order to solve the above-mentioned problems, the present invention employs a raw water tank for storing raw water to be purified, and an organic substance in the raw water flowing from the raw water tank for anaerobic bacteria. An anaerobic tank for decomposing into methane gas, carbon dioxide gas and the like, and an aeration tank provided in the next stage of the anaerobic tank for decomposing while aeration of residual organic matter not treated in the anaerobic tank using activated sludge. A first sedimentation tank for precipitating and separating sludge in the treated water treated by the aeration tank, and the treated water separated in the first sedimentation tank are caused to flow in and filtered by using a filter medium. A filter material cleaning type filtering device that separates the waste water after cleaning the filter material into the waste water after cleaning the filter material, and returns the waste water to the raw water tank side, and the filter material cleaning type filter device provided in the next stage of the filter material cleaning type filter device. Inflow of clean wastewater that has been purified by a filtration device From the second settling tank, which separates and precipitates the remaining sludge in the clean wastewater and discharges the supernatant water, and a dehydration treatment device that dehydrates the sludge settled in the second settling tank. .

Further, the first settling tank is set so that its water surface level is higher than that of the filter material washing type filtration device, and the treated water from the first settling tank is set to the filter material washing type filtration device. It is preferable to make it flow into the inside from the lower end side.

[0011]

With the above structure, the raw water to be purified is stored in the raw water tank, flows from the raw water tank into the anaerobic tank, and the organic matter is decomposed into methane gas, carbon dioxide gas, etc. by the anaerobic bacteria in the anaerobic tank. To be done. Next, in the treated water, in the aeration tank provided in the next stage of the anaerobic tank, the residual organic matter not treated in the anaerobic tank is decomposed into sludge and the like by activated sludge, and the treated water is removed by the first settling tank. Sludge in the treated water that has been aerobically treated in the aeration tank is precipitated and separated. And the first
The supernatant water of the treated water separated in the settling tank is filtered by the filter material in the filter material washing type filtration device to be separated into clean wastewater and waste water after cleaning the filter material, and the waste water is returned to the raw water tank side. The clean waste water flows into the second settling tank. next,
The clean wastewater that has flowed into the second settling tank is discharged after the residual sludge is precipitated and separated, and the supernatant water is discharged. The precipitated sludge is dehydrated by the dehydration processing device and discarded.

Further, the first settling tank is set so that its water surface level is higher than that of the filter material washing type filtration device,
If the treated water from the first settling tank is caused to flow into the filter material washing type filtration device from the lower end side thereof, the treated water in the first settling tank is always kept at a constant pressure of a water surface level difference. It flows statically into the filter media washing filter.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A wastewater treatment apparatus according to an embodiment of the present invention will be described below with reference to FIGS.

In FIG. 1, reference numeral 1 denotes a wastewater treatment apparatus for cleaning factory wastewater containing organic substances emitted from a food factory or the like. The wastewater treatment apparatus 1 includes a raw water tank 2, an anaerobic tank 4 and an aeration tank, which will be described later. The tank 7 is mainly composed of a tank 7, a first settling tank 9, a filter material washing type filtration device 11, a second settling tank 14, a dehydration treatment device 17, and the like.

First, reference numeral 2 denotes a raw water tank for storing factory wastewater flowing in through a pipe 3 as raw water. Inside the raw water tank 2, a contaminant removal screen (not shown) for removing contaminants in the raw water is shown. No) is provided. The raw water tank 2 may include an adjusting tank, an acid producing tank, and the like.

Reference numeral 4 denotes an anaerobic tank connected to the raw water tank 2 via a pipe 5, and anaerobic bacteria are cultivated in the anaerobic tank 4. Further, a gas pipe 6 is provided on the upper end side of the anaerobic tank 4, one end side of the gas pipe 6 is connected to a methane gas recovery device (not shown) provided in the anaerobic tank 4, and the other end side is connected. It is connected to a boiler (not shown) for heating the anaerobic tank 4.

When the raw water in the raw water tank 2 flows in through the pipe 5, the anaerobic tank 4 decomposes the organic matter in the raw water into methane gas, a small amount of carbon dioxide gas and sludge. Further, the methane gas generated at this time is recovered by the methane gas recovery device and supplied as fuel to the boiler via the gas pipe 6, and the anaerobic tank 4 is heated by this boiler to keep the anaerobic bacteria at an appropriate temperature and activate the anaerobic bacteria. It has become.

Reference numeral 7 denotes an aeration tank provided next to the anaerobic tank 4,
One end of 8 is connected to the anaerobic tank 4, and the other end is connected to the aeration tank 7.
Showing the pipes connected to the upper end side of the aeration tank 7
The activated sludge is cultivated therein, and an air pipe 7A is provided through the upper end side thereof. The air pipe 7A is an air supply mechanism provided in the aeration tank 7 for activating the activated sludge. (Not shown). Further, the other end side of the pipe 8 is connected so as to extend downward so that the treated water from the anaerobic tank 4 flows downward toward the aeration tank 7.

The aeration tank 7 supplies air to the air supply mechanism through the air pipe 7A to aerate the inside of the aeration tank 7 and into the treated water flowing from the anaerobic tank 4 through the pipe 8. This organic sludge is decomposed into sludge and carbon dioxide by this activated sludge. At this time, the pipe 8 causes the treated water warmed in the anaerobic tank 4 to flow into the lower side of the aeration tank 7 to suppress heat radiation from the water surface to keep the treated water at an appropriate temperature and to further remove the activated sludge. It is designed to be activated.

Reference numeral 9 denotes a first settling tank (hereinafter referred to as the first settling tank 9) connected to the aeration tank 7 via a pipe 10.
The first settling tank 9 is for allowing the sludge in the treated water that has flowed in from the aeration tank 7 through the pipe 10 to naturally settle and settle and separate. The water level of the first settling tank 9 is set to be higher than the water level of the filter material washing filter 11, so that the first settling tank 9 does not need to use a pump or the like and is supplied via a pipe 12 described later. Treated water is always supplied to the filter material washing type filtration device 11 at a constant pressure.

Further, the first settling tank 9 is connected to the aeration tank 7 by a pipe (not shown) different from the pipe 10, and the sludge settled in the first settling tank 9 is periodically passed through this pipe. It is made to flow into the aeration tank 7 and repeatedly subjected to aerobic treatment to surely decompose organic substances.

Reference numeral 11 denotes a filter medium washing type filtration device (hereinafter referred to as filtration device 11) connected to the first settling tank 9 through a pipe 12. The filtration device 11 has a lower end side as shown in FIG. A conical filter tank 11A having a downwardly reduced diameter, and a riser pipe 11C positioned in the filter tank 11A and coaxially extending, and having a lower end side serving as a gas-liquid mixing section 11B. The sand cleaning section 11E is formed in a stepped cylindrical shape surrounding the upper end side of the rising pipe 11C, and the lower end side of the sand cleaning section 11E has a cleaning passage 11D, and the sand cleaning section 11E is provided near the outer periphery of the sand cleaning section 11E. An overflow weir 11F for keeping the inside at a predetermined water surface level, and the sand cleaning section 11
An outlet 11G is provided on the outer peripheral side of E for discharging the cleaning wastewater flowing out from the overflow weir 11F, and is provided on the outer peripheral side of the upper end of the filtration tank 11A.
An overflow weir 11H that keeps the water level on the outer peripheral side of 1E higher than the water level in the sand cleaning section 11E, and a discharge port that is provided on the upper end side of the filtration tank 11A and discharges the clean wastewater flowing out from the overflow weir 11H. 11
J, an air pipe 11K for supplying compressed air to the gas-liquid mixing section 11B to form an ascending flow in the ascending pipe 11C, and a filter sand S as a filter medium filled in the filter tank 11A. It is constructed and disclosed in JP-A-61-2910.
Although it has substantially the same structure as the downflow type biofilm purification device disclosed in 99, the lower end side of the filtration device 11 is
The upper end side penetrates into the filtration tank 11A, and the lower end side is the pipe 1
A plurality of injection pipes 11L and 11L (only two pipes are shown) connected to 2 are provided.

Next, the filtering device 11 thus constructed
The operation of will be described.

First, the supernatant water in the first settling tank 9 does not use a pump like the other pipes 5, 8 and 10 due to the difference in water level between the first settling tank 9 and the filtering device 11. It is constantly supplied at a constant pressure through the pipe 12, and the filtration tank 1 is statically supplied from each injection pipe 11L without making a splash.
The sludge or the like flows into the inside of 1A, is filtered by the filtering sand S, rises, flows out from the overflow weir 11H, and is discharged as clean waste water from the discharge port 11J.

At this time, the filtering sand S, which is obtained by filtering the supernatant water and adhering sludge or the like, gradually moves to the lower side of the filtering tank 11A by its own weight, and the rising flow in the rising pipe 11C causes the rising pipe 11C to rise. It is sucked into the inside and washed while rising with compressed air and supernatant water. Also, the rising pipe 11C
The filtered sand S discharged from the upper end side of the same moves downward in the washing passage 11D and is washed again by the clear water flowing upward in the washing passage 11D due to the water surface level difference (pressure difference) to remove sludge and the like. It is deposited on each injection pipe 11L in a state of being sufficiently removed. Then, the supernatant water obtained by washing the filter sand S in the rising pipe 11C and the washing passage 11D and mixed with sludge or the like flows out from the overflow weir 11F as the sewage after washing, and is discharged from the discharge port 11G. It is returned to the inside of the raw water tank 2 through the pipe 13 connected to the.

Reference numeral 14 denotes a second settling tank (hereinafter referred to as a second settling tank 14) connected to the outlet 11J of the filtering apparatus 11 via a pipe 15, and the second settling tank 14 is the filtering apparatus. The residual sludge, which cannot be completely removed by the filtration device 11 in the clean waste water flowing from 11 through the pipe 15, is precipitated and separated. A discharge pipe 16 is attached to the upper end of the second settling tank 14, and the discharge pipe discharges the supernatant water in the second settling tank 14.

Reference numeral 17 denotes a dehydration treatment apparatus connected to the second settling tank 14 through a pipe 18, and the dehydration treatment apparatus 17
Is for discharging sludge that has settled in the second settling tank 14 in a cake-like state after being dehydrated. Further, the treated water generated during this dehydration treatment is returned to the raw water tank 2 through the pipe 19.

The waste water treatment apparatus 1 according to this embodiment has the above-mentioned structure, and its operation will be described below.

First, when factory wastewater containing organic substances is discharged, this wastewater (raw water) flows into the raw water tank 2 through the pipe 3 and is temporarily stored in the raw water tank 2. At this time, In addition, relatively large contaminants are removed by a contaminant removal screen. Next, the raw water in the raw water tank 2 is pumped up through the pipe 5 or the like and flows into the anaerobic tank 4, and in the anaerobic tank 4, the organic matter is converted into methane gas and a small amount of carbon dioxide gas and sludge by anaerobic bacteria. It is disassembled. Here, the methane gas generated in the anaerobic tank 4 is recovered by a methane gas recovery device and supplied to a boiler or the like via a gas pipe 6 to bring the anaerobic tank 4 to a predetermined temperature range to activate anaerobic bacteria. It is designed to be used as a fuel for holding.

Then, the treated water decomposed in the anaerobic tank 4 flows into the aeration tank 7 through the pipe 8, and the aeration tank 7 is aerated.
Residual organic substances that could not be completely decomposed by the above-described anaerobic treatment are decomposed into activated sludge into sludge and carbon dioxide gas. Next, the treated water re-decomposed by the aerobic treatment is supplied to the first settling tank 9 through the pipe 10.
In the first settling tank 9, the sludge is settled by natural sedimentation,
To be separated. The sludge settled at this time is returned to the aeration tank 7 and repeatedly subjected to aerobic treatment. Then, when the sludge settling in the first settling tank 9 is completed, only the purified supernatant water is injected into the filtering device 11 from the pipe 12 through each injection pipe 11L and filtered by the filtering sand S. Only the clean waste water flows into the second settling tank 14 through the pipe 15. Further, the sewage obtained by washing the filter sand S and mixed with sludge or the like is returned to the inside of the raw water tank 2 through the pipe 13, and the above-mentioned treatment is repeatedly performed.

Next, in the clean waste water that has flowed into the second settling tank 14 through the pipe 15, the remaining sludge that cannot be completely filtered by the filter device 11 is settled and separated, and only the supernatant water is discharged into the discharge pipe. It is discharged via 16. Also, the second
The sludge settled in the settling tank 14 is supplied to the dehydration processing apparatus 17 through the pipe 18, and is dehydrated in the dehydration processing apparatus 17 to be discarded as cake-like industrial waste. On the other hand, the treated water generated during the dehydration treatment is returned to the raw water tank 2 through the pipe 19 and the filtration device 1
The wastewater generated in No. 1 will be reprocessed.

Thus, according to the present embodiment, the first settling tank 9 and the second settling tank 14 are provided, and the filtration device 11 is installed at the stage subsequent to the first settling tank 9 so that Since only the supernatant water is filtered and the clean waste water filtered by the filtering device 11 is again settled and separated in the second settling tank 14, the filtering process is performed in a state where the load on the filtering device 11 is reduced. In addition, it is possible to sufficiently settle and separate in the second settling tank 14, and it is possible to satisfy the water quality standard of the wastewater and to greatly improve the reliability.

Further, sludge that has settled in the first settling tank 9 is allowed to flow into the aeration tank 7 again to be repeatedly subjected to aerobic treatment, and the wastewater obtained by washing the filter sand S discharged from the filtering device 11 is washed in the raw water tank 2 The sludge generated in the first settling tank 9 and the filtering device 11 can be decomposed into methane gas and carbon dioxide gas by repeating anaerobic treatment and aerobic treatment because the purification treatment is repeated by returning it to It is possible to reduce the amount of sludge discharged from the dehydration treatment device 17 to reduce the waste treatment fee and the labor cost, and to significantly reduce the cost.

On the other hand, the first settling tank 9 is formed with a water surface level higher than that of the filtration device 11, and the supernatant water of the first settling tank 9 is supplied from the pipe 12 through each injection pipe 11L to the lower end side of the filtration device 11. Therefore, the supernatant water in the first settling tank 9 is always supplied to each injection pipe 11L at a constant pressure due to the difference in water surface level without using a pump or the like, and the water is sprayed from each injection pipe 11L. It can be statically injected into the filtration device 11 without raising the pressure, and can suppress a decrease in filtration efficiency due to turbulence or the like to enhance the filtration capacity of the filtration device 11 and cope with a rapid increase in factory wastewater. .

In the above embodiment, the waste water treatment apparatus 1 for cleaning the factory waste water containing the organic substances of the food factory has been described as an example, but the present invention is not limited to this, and the waste water is discharged from a general house or the like. It may be used to clean domestic wastewater containing organic matter.

[0036]

As described in detail above, according to the present invention, a filter material washing type filtration device is provided between the first settling tank and the second settling tank, and Since the discharged wastewater after cleaning the filter medium is returned to the raw water tank, it is possible to filter the treated water with the filter medium cleaning type filter device while reducing the load on the filter medium cleaning type filter device. In addition to meeting the water quality standards for wastewater and improving reliability, it is possible to reduce the amount of sludge discharged from the dehydration treatment equipment, reduce waste treatment fees and personnel costs, and reduce costs. Can be planned.

Furthermore, the first settling tank is set so that its water surface level is higher than that of the filter material washing type filtration device, and the treated water from the first settling tank is set in the filter material washing type filtration device. Since it is made to flow from the lower end side, the treated water in the first settling tank is always made to flow statically into the filter material washing type filtration device at a constant pressure with a water surface level difference without splashing. Therefore, it is possible to suppress the deterioration of the filtration efficiency due to the turbulent flow and to enhance the filtration capacity of the filter material washing type filtration device.

[Brief description of drawings]

FIG. 1 is a system diagram showing a wastewater treatment device according to an embodiment of the present invention.

FIG. 2 is an enlarged vertical cross-sectional view showing the internal structure of the filter-medium cleaning type filter device in FIG.

[Explanation of symbols]

 1 Wastewater treatment device 2 Raw water tank 4 Anaerobic tank 7 Aeration tank 9 First settling tank 11 Filter material washing type filtration device 14 Second settling tank 17 Dehydration processing device S Filtered sand (filter material)

Claims (2)

[Claims] 1. A raw water tank for storing raw water to be purified, an anaerobic tank for decomposing organic matter in the raw water flowing from the raw water tank into methane gas, carbon dioxide gas and the like using anaerobic bacteria, and a stage next to the anaerobic tank. And an aeration tank for decomposing and treating residual organic matter that has not been treated in the anaerobic tank while using aerated sludge, and a sludge for precipitating and separating sludge in the treated water treated by the aeration tank Of the settling tank and the treated water separated in the first settling tank, and is filtered using a filter material to separate into clean drainage water and waste water after cleaning the filter material, and the waste water is fed to the raw water tank side. A filter material washing type filtration device that returns to
The residual sludge in the clean drainage is separated and settled by injecting the clean drainage, which is provided in the next stage of the filter drainage cleaning filter, and which is purified by the filter drain cleaning filter, and the supernatant A wastewater treatment device comprising a second sedimentation tank for discharging water and a dehydration treatment apparatus for dehydrating sludge settled in the second sedimentation tank. 2. The first settling tank is set so that its water surface level is higher than that of the filter material washing type filtering apparatus, and the treated water from the first settling tank is set to the filter material washing type filtering apparatus. A structure in which it is made to flow into the inside from the lower end side thereof.
Wastewater treatment equipment described in.