JP2002336884A - Waste water treating device and waste water treating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently purify the waste water in which water quantity and water quality are timewisely varied in the state where the load to be exerted to the treating function using microorganism is reduced. SOLUTION: In a waste water treating device in which the waste water containing organic pollutants and whose water quantity and water quality are timewisely varied is supplied to the water treating device using microorganism to continuously purify the waste water, a waste water regulating tank having a plurality of waste water withdrawal ports in the flow direction of the waste water supplied to the device and a means for simultaneously discharging the waste water different in inflow time from the plurality of waste water withdrawal ports and for supplying the waste waters to the water treating device using microorganism after joining these waste waters are provided on the upstreamside of the water treating device using microorganism.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wastewater treatment apparatus and a wastewater treatment method for treating by utilizing microorganisms, and more particularly to treating wastewater whose water quality and flow rate fluctuate with time while reducing the load on the apparatus. And a wastewater treatment method.

[0002]

2. Description of the Related Art In recent years, interest in environmental problems has been rapidly increasing, and various wastewaters derived from various human activities have generated odors, eutrophication of lakes and marshes, deterioration of landscapes, and effects on ecosystems. The problems related to the water environment in urbanized areas, such as drinking water, have become apparent. One of them is a problem related to a wastewater treatment device and a wastewater treatment method for homes and the like.

[0003] Wastewater from households and the like is mainly composed of organic substances reflecting human life patterns. In consideration of the environment, a water treatment apparatus utilizing microorganisms such as a biological filter method is used for the treatment. Used. However, as a result of reflecting human life patterns, the amount and quality of these wastewaters fluctuate greatly over time. Fluctuations in the volume and quality of the wastewater cause a temporal variation in the pollutant load expressed as the product of the concentration and the flow rate of the wastewater. There is a problem that the efficiency is reduced. Conventionally, the following solutions have been proposed for the problem of deterioration of treated water quality due to unevenness in the amount or quality of water in wastewater.

(1) A method of temporarily storing treated raw water in an inflow pipe and controlling a gate opening degree (JP-A-58-1598)
95) (2) Using a treatment septic tank and BOD detection means divided into two or more tanks, high BOD wastewater is dispersed into the upstream anaerobic tank and low BOD wastewater is dispersed into the downstream anaerobic tank to disperse the treatment by microorganisms. (3) Also paying attention to BOD, high BOD drainage and low BO
D by direct mixing of the concentrated wastewater (Japanese Patent Laid-Open No. 6-55)
172)

[0005] In (1), macroscopic temporal fluctuations in water volume and water quality are reduced by means of water storage and discharge, and in (2) and (3), BOD is dispersed in Merkmal by treatment or uniformity of wastewater concentration by wastewater concentration. I'm trying.

[0006]

However, there has been a problem which has not been addressed in each of the above conventional methods. That is the effect of a synthetic detergent that significantly reduces the function of a microorganism-based water treatment apparatus such as a biological filter method. Surfactants that constitute a synthetic detergent are generally difficult to decompose using microorganisms. Further, the biofilm is easily adsorbed by the biofilm, whereby the required amount of oxygen is insufficient, and the biofilm cannot perform its intended function. Therefore, when a large amount of wastewater containing such a synthetic detergent is generated in a short time in a specific time zone (for example, washing wastewater), the function of the microorganism-based water treatment apparatus is increased due to a sudden increase in the pollution load. , The treatment efficiency was reduced, the quality of treated water was deteriorated, and the load on the environment was increased.

When the drainage source is a house group, the household wastewater as collective drainage indicates the total flow rate of the house group and the water quality averaged over the house group. Therefore, as the number of houses increases, the pollution load becomes more microscopic. Although it is considered that the time fluctuation is reduced to some extent as compared with the case where the number of houses is small, a large amount of washing drainage still flows in the morning, and thus the above problem exists.

[0008] An object of the present invention is to reduce the fluctuation of the pollutant load with time in the wastewater treatment of wastewater in which the amount of water and the quality of water fluctuate with time to consume dissolved oxygen in the water and generate odors. It is an object of the present invention to propose a wastewater treatment apparatus and method for removing organic pollutants that cause environmental degradation with high efficiency and with a reduced load on a microorganism-using water treatment apparatus.

Another object of the present invention is to solve the above-mentioned conventional problems by providing an apparatus and a method having a low utility and a simple structure without using a mechanical stirring device as a basic structure, thereby reducing costs. It is to plan.

[0010]

Means for Solving the Problems In order to achieve the above object, the present inventors have investigated the relationship between the flow rate, water quality and purification characteristics of domestic wastewater, and have obtained the following findings. That is, in the cycle of the day, the domestic wastewater discharged during the time period from evening to midnight usually does not include the washing wastewater, or even if it does, the amount thereof is small.
For this reason, domestic wastewater discharged during this time zone is relatively easily purified by the microorganism-based water treatment device even when the pollution load is large. On the other hand, in the morning (approximately from about 7 am to about 10 am)
A large amount of washing drainage is discharged. As described above, even in the domestic wastewater, if there is a treated raw water area having a different water quality formed depending on the time of day, the laundry wastewater instantaneously exhibits an extremely high COD value, so that the pollution load suddenly increases. In this case, the processing capacity of the water treatment apparatus utilizing microorganisms is exceeded. Further, since the washing wastewater contains surfactants as described above, it is not only difficult to decompose the wastewater by the microorganism-based water treatment apparatus, but also the biofilm constituting the main function of the apparatus may be damaged. I understand. The present inventors have conducted intensive studies on treated raw water having different water quality zones formed according to time zones, and as a result, for example, extracting the wastewater from the treated raw water areas having different water qualities and mixing them, the above problem has been solved. Found to be solved. That is, the invention claimed in the present application is as follows. (1) In a wastewater treatment apparatus for continuously purifying wastewater which contains organic pollutants and whose flow rate and water quality fluctuates with time to a water treatment apparatus utilizing microorganisms, the upstream of the water treatment apparatus utilizing microorganisms A drainage adjusting tank having a plurality of drainage outlets in the flow direction of the wastewater supplied to the apparatus, and drainage waters having different inflow times are simultaneously extracted from the plurality of outlets, and these are combined to form the microorganism-using water treatment. A wastewater treatment device, comprising: means for supplying the wastewater to the device. (2) The wastewater treatment apparatus according to (1), wherein the wastewater adjusting tank has a unit for suppressing backflow mixing of the wastewater. (3) In the wastewater treatment apparatus according to the above (1) or (2), the time difference between the drainage extracted from each of the first extraction outlet and the last extraction outlet among the plurality of extraction outlets of the drainage adjusting tank is 30. A wastewater treatment method characterized in that the wastewater treatment time is at least about one minute. (4) In the wastewater treatment apparatus according to the above (1) or (2), drainage from the drainage outlet of the wastewater adjustment tank is controlled so that the pollution load of wastewater supplied to the microorganism-based water treatment apparatus is equal to or less than a predetermined value. A wastewater treatment method characterized by adjusting the extraction amount.

In the present invention, examples of the wastewater whose water quality and flow rate to be treated fluctuate over time include wastewater in which the content of pollutants fluctuates over time, such as domestic wastewater, but is not limited thereto. is not. Taking domestic wastewater as an example, the sources of domestic wastewater are kitchens,
Examples include a bathtub, a washing machine, a washroom, a toilet septic tank, and the like, but the components constituting the pollutants in each wastewater are different. In other words, organism-derived organic matter discharged from the kitchen or bath tub, such as food residue or waste from the body, can be relatively easily decomposed by the treatment function using microorganisms such as a biological filter, while washing wastewater is used. As described above, the surfactants constituting the synthetic detergent which are contained in a large amount are difficult to decompose. Further, surfactants are suddenly discharged at a high concentration and are easily adsorbed to a biofilm, so that a water treatment apparatus utilizing microorganisms such as a biological filter bed cannot exhibit its intended function. Therefore,
During a time period when a large amount of washing wastewater is discharged, the intended purification performance of the wastewater treatment device may be reduced due to a large amount of water and a large amount of synthetic detergent. On the other hand, during the period when the washing drainage is not discharged, the amount of water is small except for the drainage of the bathtub drainage, and the problem due to the inclusion of the synthetic detergent does not usually occur. Therefore, even in such domestic wastewater, areas having different water qualities are formed in a continuous flow of the wastewater depending on the time zone. The present invention is suitable for treating such wastewater.

The drainage adjusting tank referred to in the present invention is a tank provided on the upstream side of the drainage supply from the settling basin to the water treatment apparatus utilizing microorganisms such as a biological filter. In the drainage adjusting tank, means for supplying or discharging wastewater so as to generate a constant flow, a plurality of drainage outlets arranged in the flow direction of the drainage, and merging the drainage simultaneously extracted from the outlet, And a pipeline for mixing and supplying the mixed water to the microorganism-based water treatment apparatus. It is preferable to provide a partition plate, for example, a partition plate that alternately protrudes from the opposing side wall in the flow direction of the drainage so as to prevent the flow of the drainage from being mixed in the adjusting tank.

[0013] Examples of the microorganism-based water treatment apparatus include a biological filter apparatus capable of easily controlling sludge and operating with low utility by utilizing a natural head. Any device that disassembles may be used.

In the present invention, the pollution load means an amount represented by a product of a pollution concentration and a flow rate of wastewater. In addition, there are BOD (biological oxygen demand) and COD (chemical oxygen demand) as Merckmar, an organic pollutant that consumes dissolved oxygen in water and causes environmental degradation such as generation of offensive odor. Uses COD to remove organic pollutants from COD
Also expressed as a component.

[0015]

According to the present invention, the wastewater to be treated flows into the regulating tank having a plurality of outlets in the flow direction of the wastewater, and the wastewater with different inflow times is extracted from the plurality of outlets of the adjusting tank, and these are merged. Supply to the downstream microbial water treatment apparatus to reduce the time variation of the pollution load in the apparatus and to efficiently remove the organic pollutants in the wastewater while reducing the load applied to the apparatus. Can be.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a flow chart of the present invention in which a drainage adjusting tank is provided between a sand basin and a microorganism-using water treatment apparatus. In FIG. 1, domestic wastewater to be treated is guided to a settling basin 1, where dirt and coarse particles in the domestic wastewater are removed there, and then, flows out of the settling basin 1 and is introduced into a drainage adjusting tank 3. . The drainage introduced into the drainage adjusting tank 3 is extracted from a plurality of outlets, merged and mixed, and then guided to a water treatment apparatus 2 utilizing microorganisms such as a biological filter, where organic pollutants are microbially decomposed. After that, it is discharged to the environment as purified water. FIG.
FIG. 2 is a model diagram showing a periphery of a drainage adjusting tank 3 in FIG. 1. In FIG. 2, domestic wastewater from the sand basin 1 is
From the drainage adjusting tank 3. In the adjustment tank 3, partitions I, II, III, and IV, which are open spaces, are formed by partition plates 22, 23, and 24 provided so as to alternately partition side walls facing the flow direction of the drainage in a direction perpendicular to the flow direction. And each compartment has a drain outlet 26, 28, 30,
32 are provided, and valves 27, 29, 31, 3
3 is connected to the branch pipe 34 and the main pipe 25.
The partition plates 22 to 24 are provided with partition plates alternately from one of the opposing side walls to the other as shown in FIG. 2 so as to block the flow of drainage in one direction in the adjustment tank 3. An opening formed by a cutout in the partition is provided between the other wall and the partition so that it can flow into the next compartment in the direction. In the above-mentioned apparatus, while the domestic wastewater from the sand basin flows into the section I of the drainage adjusting tank 3 from the pipe 21, and then passes through the sections II, III, and IV partitioned by the partition plates 22, 23, and 24, A predetermined amount of wastewater is simultaneously withdrawn from the outlets 26, 28, 30, and 32 provided in each section via valves 27, 29, 31 and 33, and passes through the branch pipe 34 and the main pipe 25. They are merged and mixed in the meantime, and supplied to the microbial water treatment apparatus 2.

In the design of the drainage adjusting tank 3, in the morning,
Ideally, the capacity of the regulating tank and the position of the outlet should be designed so that the domestic wastewater belonging to each time zone from evening to midnight is mixed, but there is a time difference of about 30 minutes or more. If about four outlets are provided at the positions, it is possible to substantially avoid sudden rise of COD, and the effect of the present invention can be practically achieved. Specifically, the drainage of each time zone extracted at the first extraction port 26 and the last extraction port 32 in FIG. 2 may be set to have a time difference of about 30 minutes or more. 30
The time on the order of minutes is the time between the discharge of the concentrated laundry drainage in the laundry and the drainage of the laundry drainage in the subsequent washing (rinsing) stage, whereby at least the initial rich and COD component in the laundry is removed. Since the washing wastewater containing a large amount of surfactants is mixed with the washing wastewater in which the COD component is more diluted in the washing (rinsing) stage, a substantial reduction in the pollution load and the load on the processing function of utilizing microorganisms is realized. Because you can.

Although the number of sections and the number of outlets in the adjusting tank 3 of FIG. 2 are four each, the present invention is not limited to these. Also, in FIG. 1, one extraction port is provided for one section, but the present invention is not limited by the number and position of the extraction ports provided for each section, the mode, and the like.

It is standard that the ratio of the amount of water extracted from each section I, II,... Of the drainage adjusting tank 3 is made equal to the storable volume of each section. Is not restricted. Each section I, I
The adjustment of the withdrawal amount from I,.
Alternatively, the flow rate may be adjusted by a flow control means such as a triangular weir.

The wastewater extracted from each section of the drainage adjusting tank 3 is joined and mixed by the branch pipe 34 and the main pipe 25, but is introduced directly into the pipe 25 without passing through the branch pipe 34. May be. According to the present invention, wastewater of different qualities is simultaneously extracted from different areas of the adjusting tank 3 and combined and mixed in a common pipe as described above. Device. Hereinafter, the present invention will be specifically described with reference examples, examples, and comparative examples.

[0021]

[Reference Example 1] Household wastewater from a group of 20 houses mainly equipped with a single septic tank is received in a 20-liter plastic tank every 10 minutes, and the flow rate is measured from the time required to fill the tank, and the COD is measured for each plastic tank. did. FIG. 3 is a graph showing the time variation of the flow rate and water quality (COD) in the morning (here, from 6 am to 10 am) measured in this way.
Shown in It can be seen that the amount of wastewater is extremely small until around 6:30 am, and the COD of the wastewater is extremely low. In addition, the first peak related to the flow rate appeared around 7:00 am, and from 8:00 to 10:00, the flow rate was consistently high and CO
It can be seen that D is also high. The washing period of the 20 units is almost between 8 am and 10 am, indicating that the drainage of the washing wastewater contains a considerable flow rate and a COD component, that is, a high pollution load.

[0022]

Example Preparation of biological filter bed A 4.5 cm diameter synthetic fibrous string filter medium was immersed for 7 days in a channel through which domestic wastewater flows to form a biofilm on the surface. The filter medium was transferred, and mud attached by aeration was washed off and adjusted to an aerobic state. The contact filter medium prepared in this way and holding a biofilm on the surface was 9.0 cm wide and 6.8 deep.
It was installed in a filter bed having a length of 3 cm and a length of 3 m to form a biological filter bed.

Preparation of Wastewater Sample Table 1 shows the method of preparing the wastewater samples prepared in Comparative Examples 1 and 2, and Examples 1 and 2.

[0024]

[Table 1]

Experiments and Evaluation of the Flow of Wastewater Samples The biological filter bed prepared above was aerated at about 30 cm intervals so as to generate fine bubbles at a temperature of 25 ° C.
Under the conditions described above, the wastewater sample was allowed to flow down to the biological filter at a flow rate of 50 mL / min (milliliter) for 30 hours to be almost in a steady state. Thereafter, the COD at each flow-down position was measured, the amount of dissolved oxygen was measured, and the presence or absence of malodor was confirmed. CO
D measurement is minimum, flow down distance 0.5m, 1.0m, 2.0
m and 3.0 m (discharge port). Table 2 shows the measurement results for various prepared wastewater samples.

[0026]

[Table 2]

Comparative Example 1 As a wastewater sample, domestic wastewater (COD) having average water quality was used.
30.8 ppm). As a result, as shown in Table 2, the COD decreased as the flow-down position decreased, and was 12.2 ppm at the outlet. The obtained effluent was at 25 ° C.
No odor was generated even when left for a long time. This indicates that the biological filter of this experiment has sufficient capacity to treat domestic wastewater having average water quality.

Comparative Example 2 A wastewater sample obtained by mixing and collecting wastewater mainly composed of laundry wastewater having a relatively high COD from a plurality of categories out of domestic wastewater collected in Reference Example 1 (COD 58.0 ppm).
Was used. As a result, as shown in Table 2, C of about Comparative Example 1 was obtained.
No decrease in OD was observed, and 35.0 pp at the outlet.
m. In addition, the amount of dissolved oxygen is 0.5 to 2.0 ppm, and a malodor is generated from the obtained effluent and the filter bed,
Purification was incomplete, with large amounts of worms in the effluent. This indicates that the biological filter of this example does not have the ability to treat laundry drainage discharged suddenly. This indicates that if the wastewater with a large pollutant load, such as laundry wastewater, that is suddenly discharged, is treated under conditions that exceed the processing capacity of the biological filter, the desired purification characteristics cannot be obtained. Was.

Example 1 As a wastewater sample, C was selected from domestic wastewater collected in Reference Example 1.
The effluent of each section having an OD of 20 to 60 ppm was collected from a plurality of sections and mixed (COD 35.0 ppm). As a result, as shown in Table 2, the COD decreased as the flow-down position decreased, and was 14.9 ppm at the outlet. Further, the dissolved oxygen amount was 2.5 to 4.5 ppm, and there was no generation of offensive odor from the filter bed and the discharged liquid. The effluent was colorless and transparent. From this, the biological filter of this example is capable of treating wastewater prepared by mixing wastewater with a lower COD with the laundry wastewater which is considered to have about 58.0 ppm of COD shown in Comparative Example 2. Was shown to be sufficient. In other words, when treating domestic wastewater by the biological filtration method, even if wastewater with a large pollutant load is generated temporarily, it is mixed with wastewater with a small pollutant load generated in other time zones to reduce the water quality. It was shown that if the target leveling was achieved, high purification performance could be obtained even with a short downflow distance.

Example 2 As a wastewater sample, wastewater (COD) newly collected from the same house group as described in Reference Example 1 from 8:00 pm to 9:00 pm
40.0 ppm) and wastewater (COD 50.0 pp) collected from 8:30 am to 9:30 am
m) (COD 45.0 ppm). As a result, as shown in Table 2, as the flow-down position was lowered, the COD was lowered, and was 18.0 ppm at the outlet. Further, the dissolved oxygen amount is 2.5 to 4.5 ppm,
There was no odor generation from the filter bed and the effluent. The effluent was colorless and transparent. In this example, the drainage collected between 8:00 pm and 9:00 pm is considered to be mainly bathtub drainage, and the drainage collected between 8:30 a.m. and 9:30 pm is mainly considered washing drainage. Can be

From this, the biological filter of the present example has COD
Even bathtub drainage (COD 40.0 ppm), whose COD is not remarkably low with respect to washing drainage of about 50.0 ppm, has sufficient ability to treat wastewater prepared by mixing these. Indicated. That is, when treating domestic wastewater by the biological filtration method, particularly when treating laundry wastewater containing a synthetic detergent composed of surfactants that cause a decrease in biological filtration function, the wastewater is discharged at other times. By mixing wastewater from drainage areas other than laundry wastewater into the laundry drainage area, even if wastewater discharged at other times contains substantial COD components, a short run-down distance However, it was shown that high purification performance was obtained.

[0032]

According to the first to fourth aspects of the present invention,
Since it is possible to reduce the time variation of the pollution load of the wastewater in which the amount and quality of the water fluctuates with time, the organic pollutants (C
OD component) can be removed with high efficiency while reducing the load on the processing function utilizing microorganisms. According to the first and second aspects of the present invention, a mechanical stirrer is not used as a basic configuration, so that the cost of the apparatus and operation can be reduced with a simple configuration and low utility.

[Brief description of the drawings]

FIG. 1 is a flowchart of the present invention.

FIG. 2 is a typical model diagram of a drainage adjusting tank used in the present invention.

FIG. 3 is a graph showing the time variation of drainage flow rate and water quality (COD) in the morning.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Settling basin, 2 ... Microorganism water treatment apparatus (biological filter etc.), 3 ... Drainage adjustment tank, 4 ... Aeration equipment, 21
... pipes, 22 to 24 ... partition plates, 26, 28, 30, 32
... Extraction ports, 27, 29, 31, 33 ... Valves, 25
... pipe (main pipe), 34 ... branch pipe, I-IV ... drainage adjustment tank section.

Continued on the front page (72) Inventor Kazunori Sato 6-9 Takaracho, Kure City, Hiroshima Prefecture Babcock Hitachi Kure Works F-term (reference) 2D063 DB01 DB07 4D027 AA02 AA14

Claims (4)

[Claims] 1. A wastewater treatment apparatus for continuously purifying wastewater which contains an organic pollutant and whose flow rate and water quality fluctuates with time to a microorganism-use water treatment apparatus, wherein the wastewater treatment apparatus comprises: On the upstream side, a drainage adjusting tank having a plurality of drainage outlets in the flow direction of wastewater supplied to the device, and drainage having different inflow times are simultaneously extracted from the plurality of outlets, and these are merged to use the microorganisms. A wastewater treatment device, comprising: means for supplying the wastewater to the water treatment device. 2. The wastewater treatment apparatus according to claim 1, wherein said wastewater adjusting tank has means for suppressing backflow mixing of wastewater. 3. The wastewater treatment apparatus according to claim 1, wherein, of the plurality of outlets of the drainage adjusting tank, the time difference between the first and the last outlets is 30 minutes. A wastewater treatment method characterized in that the amount of wastewater is not less than about. 4. The wastewater treatment apparatus according to claim 1, wherein the wastewater from the wastewater regulating tank is drained so that the pollution load of wastewater supplied to the microorganism-based water treatment apparatus is equal to or less than a predetermined value. A method for treating wastewater, comprising adjusting the amount.