JPH07232191A - Oxidation ditch-type waste water treating device and its centralized control system - Google Patents

Abstract

PURPOSE:To obtain the discharge of COD at a low cost without using an expen sive flow indicating and integrating meter conventionally used to obtain the COD discharge per 24hr of the treated water discharged from an oxidation ditch-type waste water treating device. CONSTITUTION:The raw water is transferred to an oxidation ditch 11 from a tank 10, aerated in the ditch, transferred to a settling tank 14 and settled, and the treated water from the settling tank is discharged through a sterilizing tank 15 by this oxidation ditch-type waste water treating device. A flow indicating and integrating meter 19 to measure the inflow of raw water to the ditch from the raw water tank is installed, and a COD meter 20 for for measuring the COD of the treated water is furnished to the sterilizing tank or in the discharge passage of treated water. Further, a computing element 22 is installed to calculate the discharge of COD per 24 hr based on the outputs from the flow indicating and integrating meter and the COD meter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention reduces the number of expensive flow rate indicating accumulators used in a conventional oxidation ditch type wastewater treatment device (hereinafter also referred to as OD type wastewater treatment device) by half and discharges the same. OD type waste water treatment equipment that makes it possible to determine the COD emission amount of treated water per day and the COD emission amount of treated water discharged from a plurality of OD type waste water treatment equipment The present invention relates to a centralized management system for a plurality of OD type wastewater treatment devices managed by a single computing unit.

[0002]

2. Description of the Related Art An OD type wastewater treatment system has a population of about 1,000, along with a wastewater treatment system using the activated sludge method or the biofilm method.
It is widely used as a wastewater treatment device for agricultural settlements that treats about 250 household wastewater and as a small-scale urban sewage treatment device. As is well known, this OD type wastewater treatment device transfers raw water that has passed through a coarse screen and a crusher from a raw water tank to an oxidation ditch, aerates the raw water with the oxidation ditch, and then moves it to a settling tank for precipitation. After processing, the treated water is discharged from the sedimentation tank through the disinfection tank. In the above-mentioned conventional OD type wastewater treatment device, when a flow passage for transferring from a raw water tank to an oxidation ditch or a flow rate adjusting tank is provided between the raw water tank and the oxidation ditch,
An inflow-side flow indicator integration meter is installed in the flow path from the raw water tank to the flow control tank to measure the inflow of raw water. Further, a COD measuring device is provided in the disinfecting tank, and a discharge-side flow-rate integrating meter is provided in the flow path of the treated water discharged from the disinfecting tank. Dedicated COD for the discharged COD per 24 hours
It is calculated by inputting it to a calculator or a personal computer.

The reason why the total amount of COD emissions of treated water per 24 hours is determined is that, depending on the region, in facilities that discharge treated water of 50 m ³ or more per day, the permissible value of COD emissions per day for each facility. Is required and it is obligatory to prove that the COD emission amount per day is less than or equal to the allowable value, or because COD ≈ BOD × 1.6 to 2.0, the BOD can be estimated by calculation. Therefore, instead of obtaining the BOD that cannot be continuously measured and cannot be obtained without manual analysis, the BOD is estimated by COD to check the treatment status, and the amount of air for aeration depending on the COD value, This is for adjusting the amount of sludge to be returned and maintaining good and normal operating conditions.

[0004]

In the above-mentioned conventional wastewater treatment equipment, a flow-indicating integrating meter on the inflow side is installed in order to measure the inflow water amount of raw water, and yet another unit is installed to calculate the COD emission amount. Is installed on the discharge side of the treated water. Since this flow rate indicator integrating meter is a very expensive device, it causes an increase in the installation cost of the device, and there is a demand for cost reduction. Further, in the above-mentioned conventional wastewater treatment device, the COD emission amount per day is calculated by calculating the outputs of the flow rate indicating integrating meter on the discharge side and the COD measuring device by a dedicated COD calculating device or a personal computer. Therefore, for example, when centrally managing 10 wastewater treatment devices, in addition to 10 arithmetic units for each wastewater treatment device, the central totalization,
A total of 11 personal computers, one for recording, is required, which requires a large amount of investment, which hinders its spread.

[0005]

The present invention is for solving the above-mentioned problems, and the OD type waste water treatment apparatus of claim 1 transfers raw water from a raw water tank to an oxidation ditch, and the raw water is processed by the oxidation ditch. After aeration treatment, the wastewater is transferred to a settling tank for settling, and the inflow amount of raw water transferred from the raw water tank to the oxidation ditch is measured in an oxidation ditch type wastewater treatment device that discharges treated water from the settling tank through a disinfection tank. And a COD measuring device for measuring the COD value of the treated water in the disinfecting tank or the discharge channel of the treated water are provided, and processing is performed by the output of the above-mentioned flow indicator integrating meter and the output of the COD measuring device. 24 of water
A feature is that a calculator for calculating the COD emission amount per hour is provided. In addition, the centralized control method of the OD type wastewater treatment device according to claim 2 is that the raw water is transferred from the raw water tank to the oxidation ditch, the raw water is aerated by the oxidation ditch, and then transferred to the settling tank for precipitation treatment, The treated water is discharged through the disinfecting tank, and the flow rate integrator that measures the inflow amount of the raw water transferred from the raw water tank to the oxidation ditch, and the COD value of the treated water in the disinfecting tank or the discharge path of the treated water. And a COD measuring device for measuring the above, and each of the above-mentioned controls of a plurality of oxidative dichtic wastewater treatment devices provided with a control panel to which the output of the flow rate indicating calculator and the output of the COD measuring device are input. It is characterized in that the panel is connected to the central processing unit by a line, and the central processing unit calculates the COD emission amount of the treated water discharged from each wastewater treatment device per 24 hours.

[0006]

1 and 2 show a typical example of an OD type waste water treatment apparatus. As described above, the raw water that has passed through the crusher and the coarse screen into the raw water tank 10 is circulated by a pump. Supply to the oxidation ditch 11 consisting of a road. The raw water is aerated by the aeration device 12 while circulating in the oxidation ditch, and mainly organic substances in the raw water are decomposed and removed by the action of the microorganisms in the ditch. The aeration device 12 is arranged on the water surface in the figure, and a part of the blades of the rotating rotor is immersed to agitate the water, and the aeration amount depends on the rotation speed of the rotor, the immersion depth of the blades, the intermittent rotation of the rotor, and the like. I showed a mechanical surface stirring aerator that can be adjusted,
Other types of aerators may be used. Since the water level in the ditch is determined by the gate type water level controller 13, the raw water stays in the ditch for about 24 to 36 hours and then overflows from the water level controller by the amount of the inflow of the raw water to cause the settling tank 1
It flows into 4, and the sludge is separated and separated into treated water.
It is discharged through the disinfection tank 15 having the chlorine disinfecting device 16 and the discharge tank 17. The daily inflow of raw water to the oxidation ditch and the daily outflow of treated water from the settling tank to the disinfecting tank are the same, although there is some time difference.

The sludge settled in the settling tank 14 is returned by the operation of the return pump P ₁ through the return circulation valve V ₂ to return about 100 to 200% of the maximum daily amount of wastewater. Excess sludge is discharged to the sludge storage tank 18 by opening a drain valve V ₁ controlled by a timer. This sludge is usually 1-2 times a day, 5-5 times a time.
Do it for 20 minutes. The amount of excess sludge drawn out is controlled by the concentration of sludge in the oxidation ditch, but normally the amount of drawn out sludge is almost constant per day, and the amount can be found by observing the fluctuation of the liquid level in the sludge storage tank to obtain the correct value. be able to. Further, since the flow rate per hour of the sludge discharge valve V ₁ is known, the amount of excess sludge drawn out can be known also by the opening time of the valve.

[0008] A flow rate indicating integrator 19 is provided in a pipeline for pumping and supplying raw water from the raw water tank 10 to the oxidation ditch 11, whereby the total inflow amount of raw water per 24 hours flowing into the oxidation ditch is provided. Then, the inflow amount for each time is known, and this is output to the arithmetic unit described later.

Since the COD emission amount per 24 hours is calculated and obtained, a COD measuring device 20, such as a COD meter and a UV meter, is provided upstream of the disinfecting device 16 so that the disinfecting tank 15 is not affected by chlorine. In addition to the provision of the COD measuring device 2
An arithmetic unit, for example, a personal computer 22 is provided which receives the output of 0 and the output of the flow rate instruction integrating meter 19 via the control panel 21 every hour, for example. The COD measuring device 20 may be provided not at the disinfection tank but at a point in the discharge passage after the disinfection tank where the influence of chlorine disappears.

The amount of excess sludge discharged to the outside of the system per day is approximately constant as described above, and it is known that how many times per day, how many times per day, and how many times per day Input to the calculator 22 whether to withdraw the amount. As for the amount of sludge drawn out and the number of times, a numerical value that actually matches the actual situation is obtained, and the value input to the arithmetic unit is corrected. As a result, the calculator calculates the inflow amount Qi of the raw water per hour output by the flow rate indicating integrator 19, and
The average COD for each hour COD output by the COD measuring device, the hourly COD discharge amount according to the input sludge withdrawal amount and time zone, and the total for 24 hours are calculated as follows. Calculate Ln = Qe · C × 10 ⁻³ kgCOD / hour Ln: COD emission amount [kgCOD / hour] Qe: Treated water discharge amount [m ³ / hour] C: Treated water COD average value [mg / standing] L = L ₁ + L ₂ + ・ ・ ・ ・ ・ ・ ・ ・ + L ₂₄ L: COD emission amount per day [kgCOD / day] Qe = Qi-Qs Qi: Raw water inflow amount [m ³ / hr] Qe: Sludge removal amount [ m ³ / hour].

Table 1 shows the inflow rate Qi of raw water and the sludge withdrawal rate Qs output by the flow rate integrator to the computing unit for each certain day. The excess sludge is drawn out between 8:00 and 20:00, and the amount of pulling out once is 5 m ³ , which is input to the calculator. Thus, the computing unit computes the 8 o'clock and 9 o'clock emissions Qe of process water, from 20:00 emissions Qe of 21 o'clock of the treated water and Qe = Qi-Qs = 10-5 = 5m 3 / h .

[Table 1]

Table 2 shows the COD measurement average value C output by the COD measuring device to the arithmetic unit on the same day. When the calculator receives the output, it calculates the COD discharge amount for each hour from the above formula Ln = Qe · C × 10 ⁻³ as shown in the table, and after 24 hours, the COD discharge amount for 24 hours. Calculate the sum of. In this way, it is possible to obtain the total COD emission amount of the treated water discharged from the oxidation ditch type wastewater treatment device in a running manner for 24 hours.

[Table 2]

In the above description, the COD emission amount was obtained by subtracting the withdrawal amount of excess sludge discharged from the system from the inflow amount of raw water, but the withdrawal amount of excess sludge is overwhelmingly greater than the inflow amount of raw water. Therefore, the COD emission amount may be calculated without ignoring the amount of excess sludge drawn out, that is, without subtracting the amount of excess sludge drawn out. In that case, it becomes as shown in Table 3.

[Table 3]

The calculator 22 can switch whether the COD discharge amount is calculated by subtracting the excess sludge withdrawal amount from the raw water inflow amount or the COD discharge amount is calculated without subtracting the excess sludge withdrawal amount. It is preferable that

As is clear from the above, the COD emission amount (C) per 24 hours of the treated water discharged from the OD type wastewater treatment device (C
The OD load) can be accurately obtained. The starting point for 24 hours is not limited to midnight, and may be any time. or,
The COD discharge amount was obtained by outputting the inflow amount of raw water and the measured average value of COD every hour.
It may be every two hours.

In FIG. 3, reference numeral 30 denotes the above-mentioned OD type waste water treatment device, and a plurality of waste water treatment devices 30-1, 30-.
It is shown that the calculation of the COD discharge amount per 24 hours of the treated water discharged from each of 2 ... 30-N is performed by one calculator 32 in the monitoring center 31. Each wastewater treatment device is provided with a control panel 21 for receiving the output of the flow rate indicating integrator 19 and the COD measuring device 20, the computing unit 22 is abolished, and the control panel 21 of each wastewater treatment device is monitored via the telephone line network 33. It is connected to the arithmetic unit 32 of the center 31. As a result, the COD discharge amount of the treated water of the plurality of wastewater treatment devices can be calculated by the single computing unit 32 in the monitoring center.

Conventionally, a computing unit for computing the COD emission amount is provided for each wastewater treatment device, and each computing unit is connected to the computing unit at the monitoring center by a telephone line network, so that there are 10 wastewater treatment devices. In the case, 10 computing units and 1 computing unit at the monitoring center are needed, totaling 11 computing units,
The equipment cost was very high. However, since only one computing unit needs to be installed in the monitoring center by the above method, the facility cost becomes very low.

[0018]

According to the first aspect of the present invention, the inflow amount of raw water flowing into the oxidation ditch is measured without using an expensive flow rate indicator integrating meter for measuring the amount of treated water discharged in order to calculate the COD emission amount. The output of the flow rate integrator
The output of an inexpensive COD measuring device that measures the COD of the discharged treated water can be input to a calculator to accurately obtain the COD discharge amount of the discharged treated water per 24 hours. In addition, since the use of one expensive flow meter is eliminated, the equipment cost will be low. According to claim 2, the computing unit for computing the COD emission amount, which is provided for one unit in the wastewater treatment device, is abolished, and a plurality of ODOs are provided by one computing unit in the central monitoring center
The COD emission amount of the treated water discharged from the D-type wastewater treatment device per 24 hours can be calculated and calculated for each OD-type wastewater treatment device, and can be centrally managed. In addition, the equipment cost is significantly reduced because no computing unit is provided in each OD type wastewater treatment device.

[Brief description of drawings]

FIG. 1 is a flow sheet of an embodiment of an OD type wastewater treatment device of the present invention.

FIG. 2 is a plan view of the wastewater treatment device of FIG.

FIG. 3 is an explanatory diagram of a centralized management system of a plurality of OD type wastewater treatment devices according to the present invention.

[Explanation of symbols]

 10 Raw Water Tank 11 Oxidation Ditch 12 Aeration Device 13 Gate Type Water Level Controller 14 Sedimentation Tank 15 Disinfection Tank 16 Chlorine Disinfector 17 Outlet Tank 18 Sludge Storage Tank 19 Flow Rate Integrator 20 COD Measuring Device 21 Control Panel 22 Computer (PC) 30 OD type wastewater treatment device 31 Monitoring center 32 Computing unit (personal computer) 33 Telephone network

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[Procedure amendment]

[Submission date] March 3, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

Table 1 shows the inflow rate Qi of raw water and the sludge withdrawal rate Qs output by the flow rate integrator to the computing unit for each certain day. The excess sludge is drawn out at the time of 8:00 and 20:00, and the amount of pulling out once is 5 m ³ , which is input to the calculator. Thus, the computing unit computes the 8 o'clock and 9 o'clock emissions Qe of process water, from 20:00 emissions Qe of 21 o'clock of the treated water and Qe = Qi-Qs = 10-5 = 5m 3 / h .

[Table 1]

Claims (2)

[Claims] 1. An oxidation ditch for transferring raw water from a raw water tank to an oxidation ditch, aerating the raw water with the oxidation ditch, and then transferring it to a sedimentation tank for precipitation treatment, and discharging the treated water from the sedimentation tank through a disinfection tank. Flow wastewater treatment apparatus, a flow rate indicator integrating meter for measuring the inflow amount of raw water transferred from the raw water tank to the oxidation ditch, and a COD measuring device for measuring the COD value of the treated water in the disinfection tank or the discharge channel of the treated water. And an arithmetic unit for calculating the COD discharge amount of the treated water per 24 hours based on the output of the flow rate indicating accumulator and the output of the COD measuring device. . 2. The raw water is transferred from a raw water tank to an oxidation ditch, the raw water is aerated by the oxidation ditch, and then transferred to a sedimentation tank for precipitation treatment, and the treated water is discharged from the sedimentation tank through a disinfection tank, A flow rate indicator integrating meter for measuring the inflow amount of the raw water transferred from the raw water tank to the oxidation ditch, and a COD measuring device for measuring the COD value of the treated water in the disinfecting tank or the discharge channel of the treated water are provided. Connect the above control panels of a plurality of oxidation ditch type wastewater treatment devices equipped with a control panel to which the output of the flow rate integrator and the output of the COD measuring device are connected to the central arithmetic unit with a line, Centralized pipe of the oxidation ditch type wastewater treatment device, characterized in that the COD emission amount of the treated water discharged from each wastewater treatment device per 24 hours is calculated by the calculator of Method.