JP3018220B2 - Oxidation ditch type wastewater treatment apparatus and its centralized management method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a conventional oxidation-ditch type wastewater treatment apparatus (hereinafter, also referred to as an OD type wastewater treatment apparatus). to the OD type waste water treatment apparatus which enables the determination of the daily COD emissions of water, the daily discharge of COD water central one being released from their multiple OD type waste water treatment apparatus OD managed by arithmetic unit
The present invention relates to a centralized management method for a plurality of wastewater treatment devices of the type.

[0002]

2. Description of the Related Art An OD-type wastewater treatment apparatus has a population of about 1,000, together with a wastewater treatment apparatus based on an activated sludge method or a biofilm method.
It has become widespread as a wastewater treatment device for agricultural settlements that treats about 250 household wastewater, and as a small-scale city 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, aerated the raw water with the oxidation ditch, and then transferred to a sedimentation tank for sedimentation. After treatment, water is discharged from the sedimentation tank through the disinfection tank. In the above-mentioned conventional OD type wastewater treatment apparatus, a flow path for transferring from the raw water tank to the oxidation ditch, or, when a flow rate adjusting tank is provided between the raw water tank and the oxidation ditch, a flow path from the raw water tank to the flow rate adjusting tank. In order to measure the inflow of raw water, an inflow-side flow rate integrator is provided. In addition, a COD measuring device is provided in the water quality measuring tank upstream of the disinfecting tank, and a flow rate integrator on the discharge side is provided in the flow path of the water discharged from the disinfecting tank.
The output of the OD measuring device and the output of the flow-rate integrator on the discharge side are used to calculate the amount of COD emissions discharged from the device per 24 hours by inputting to a dedicated COD calculator or a personal computer and calculating the amount.

[0003] The reason for calculating the total COD emission per 24 hours of discharged water is that, depending on the area, 50 m ^{3 of} water per day is used.
As mentioned above, COD per day for each facility
Because the allowable value of COD emission is determined and the proof that the daily COD emission is below the allowable value is required, or because COD ≒ BOD × 1.6 to 2.0 The BOD can be estimated by calculation, whereby continuous measurement cannot be performed, and instead of calculating the BOD that cannot be obtained by manual analysis, the BOD is estimated by COD to check the processing status, and aeration is performed based on the value of COD. The purpose is to adjust the amount of air for use and the amount of returned sludge to maintain good and normal operating conditions.

[0004]

In the above-mentioned conventional wastewater treatment apparatus, an inflow-side flow rate integrator is installed to measure the amount of inflow of raw water, and another one is used to calculate the amount of COD discharge. Is installed on the discharge side . Since this flow indicator integrator is a very expensive device, it causes an increase in the installation cost of the device, and a reduction in cost is demanded. Further, in the above-mentioned conventional wastewater treatment apparatus, the output of the flow rate integrator on the discharge side and the output of the COD measuring device are calculated by a dedicated COD calculator, a personal computer, or the like, to determine the amount of COD emission per day. Therefore, for example, in the case of centrally managing 10 wastewater treatment devices, a total of 11 personal computers, one for central counting and recording, are required in addition to the 10 arithmetic units for each wastewater treatment device. It requires a large amount of investment and hinders its spread.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an OD type wastewater treatment apparatus according to claim 1 transfers raw water from a raw water tank to an oxidation ditch, and converts the raw water into an oxidation ditch. Is transferred to a sedimentation tank after aeration treatment, and is subjected to sedimentation treatment. Further, in an oxidation ditch type wastewater treatment device that is discharged from the sedimentation tank through a disinfection tank, a flow rate for measuring an inflow amount of raw water transferred from the raw water tank to the oxidation ditch. Integrator and disinfection tank
And a COD measuring device for measuring the COD value of water is provided in a water quality measuring tank upstream of the tank or a discharge channel downstream of the disinfecting tank, and water discharged by the output of the flow rate indicating integrator and the output of the COD measuring device. And a calculator for calculating the amount of COD emission per 24 hours. In addition, O in claim 2
Centralized management of D-type waste water treatment apparatus, transfer the raw water from the raw water tank to the oxidation ditch, the raw water in oxidation ditch and precipitation treatment transferred to settling tank After aeration, discharged through the disinfecting bath from further sedimentation tank So that
A flow rate integrator that measures the inflow of raw water transferred from the raw water tank to the oxidation ditch, and upstream of the disinfection tank
COD of water in the water quality measurement tank or the discharge channel downstream of the disinfection tank
A COD measuring device for measuring the value, and a control panel to which the output of the flow rate indicating calculator and the output of the COD measuring device are input. The control panel is connected to a central processing unit via a line, and the central processing unit calculates COD emissions per 24 hours of water discharged from each wastewater treatment device.

[0006]

1 and 2 show a typical example of an OD type wastewater treatment apparatus. As described above, raw water flowing into a raw water tank 10 through a crusher and a coarse screen is circulated by a pump. It is supplied to an oxidation ditch 11 composed of a road. Raw water is aerated by the aeration device 12 while circulating in the oxidation ditch, and mainly organic matter in the raw water is decomposed and removed by the action of microorganisms in the ditch. The aeration device 12 is disposed 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 amount of aeration is determined by the number of rotations of the rotor, the immersion depth of the blades, the intermittent rotation of the rotor, and the like. Although a mechanical surface stirring and aeration device that can be adjusted is shown,
Other types of aeration devices 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 24-36 hours, and then overflows the water level controller by the inflow of the raw water to settle the tank 1
Flows into the 4, separated precipitate fraction sludge in thisゝ, chlorination 16
The water is discharged through a disinfection tank 15 and a discharge tank 17 having The daily inflow of raw water into the oxidation ditch and the daily outflow of water flowing from the sedimentation tank to the disinfection tank are in agreement, albeit with some time lag.

[0007] The precipitated sludge in the settling tank 14, through the return cycle valve V ₂ by the operation of the return pump P _1, and returns 100 to 200% of the maximum sewage daily dose. Excess sludge is discharged to the sludge storage tank 18 by opening the Haidoroben V ₁ which is controlled by a timer. This sludge is usually collected once or twice a day,
Perform for 20 minutes. The amount of excess sludge withdrawn is controlled by the concentration of sludge in the oxidation ditch. Usually, the amount of withdrawal per day is almost constant, and the amount is determined by observing fluctuations in the liquid level of the sludge storage tank. be able to. Further, the time per flow Haidoroben V ₁ was known, withdrawal of excess sludge by opening time of the valve is seen.

[0008] A flow indicator integrator 19 is provided in a conduit for pumping and supplying raw water from the raw water tank 10 to the oxidation ditch 11, whereby the total inflow 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 an arithmetic unit described later.

In order to calculate and obtain the COD emission per 24 hours to be discharged , the water quality measurement tank 2 is provided upstream of the disinfection tank 15.
3 to install a COD measuring device 20, for example, a COD meter, a UV meter, etc., and output the output of the COD measuring device 20 and the output of the flow rate integrator 19 via a control panel 21, for example, every hour. , A personal computer 22 is provided. The COD measuring device 20 may be provided not at the upstream of the disinfection tank but at a point in the discharge channel after the disinfection tank where the influence of chlorine is eliminated.

[0010] As described above, the amount of surplus sludge discharged to the outside of the system per day is almost constant, and it is known. Whether the amount is to be extracted is input to the calculator 22. The sludge withdrawal amount and the number of times are obtained by obtaining a numerical value that is sometimes true, and correcting the value input to the arithmetic unit. Thus calculator from inflow Qi of raw water 1 hour every flow indicator integrated meter 19 outputs
Qe obtained by subtracting the sludge withdrawal amount Qs, the measured average value C of hourly COD output by the COD measuring device, the hourly COD discharge amount Ln according to the input sludge withdrawal amount and time zone, and the like. The total L for 24 hours is calculated as follows. When the sludge withdrawal amount Qs is 0, Qe
= Qi . ^{Ln = Qe · C × 10 -3} kgCOD / hr ........ (Equation 1) ln: COD emissions [KgCOD / h] Qe: discharge amount of water [m ³ / h] C: to discharge COD average value of water [mg / falling] _{L = L 1 + L 2 +} ········ + L 24 L: COD emissions per day [KgCOD / day] wherein a It is.

Table 1 shows the inflow amount Qi of raw water and the sludge withdrawal amount Qs output by the flow rate integrator to the calculator at each hour of a certain day. Excess sludge is extracted at 8:00 and 20:00, and the amount of one extraction is 5 m ³ , which is input to the calculator. Thus, computing unit 9 o'clock of water from 8:00
Discharge rate Qe and the water discharge rate Q between 20:00 and 21:00
e Is calculated.

[Table 1]

Table 2 shows the average value C of the COD for each time output from the COD measuring device to the arithmetic unit on the same day. Upon receiving the output, the arithmetic unit calculates the COD emission amount per hour from the above-mentioned equation Ln = Qe · C × 10 ⁻³ as shown in the table, and the COD emission amount per 24 hours after 24 hours have elapsed. Calculate the sum of In this manner, the total COD emission per 24 hours of the water discharged from the oxidation ditch type wastewater treatment apparatus in a hanging manner can be obtained.

[Table 2]

In the above description, if the amount of excess sludge drawn out Qs from the system is subtracted from the amount of raw water inflow Qi, water
The amount of release is determined. Then, the COD emission amount was obtained by the above equation 1 , but since the amount of surplus sludge withdrawn was overwhelmingly smaller than the amount of inflow of raw water, the amount of surplus sludge withdrawal was ignored.
In other words, release the excess sludge without subtracting the amount
Calculate the amount of water discharged, and then discharge COD according to Equation 1 above.
The quantity may be determined . In that case, the results are as shown in Table 3.

[Table 3]

The calculator 22 can switch between calculating the COD emission amount by subtracting the excess sludge withdrawal amount from the raw water inflow amount, or calculating the COD emission amount without subtracting the excess sludge withdrawal amount. It is preferable to keep it.

As is apparent from the above, even if an expensive flow rate integrator is not used on the discharge side, the COD discharge amount (COD) per 24 hours of the water discharged from the OD type wastewater treatment apparatus is not required.
Load) can be determined accurately. The 24-hour starting point is not limited to midnight, and may be any time. Further, the inflow amount of raw water and the measured average value of COD are output every hour to obtain the COD emission amount, but this may be every 30 minutes, every 2 hours, or the like.

In FIG. 3, reference numeral 30 denotes the above-mentioned OD type wastewater treatment apparatus, and a plurality of wastewater treatment apparatuses 30-1 and 30-.
2 indicates that the calculation of the COD emission per 24 hours of the treated water discharged from each of the 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 outputs of the flow rate integrator 19 and the COD measuring device 20 and the computing unit 22 is abolished. The control panel 21 of each wastewater treatment device is monitored via a telephone network 33. It is connected to a computing unit 32 of the center 31. Thereby, the COD emissions of the treated water of the plurality of wastewater treatment devices can be calculated by one calculator 32 in the monitoring center.

Conventionally, each of the wastewater treatment apparatuses is provided with an arithmetic unit for calculating the COD emission amount, and each of the arithmetic units is connected to an arithmetic unit at the monitoring center via a telephone network. Therefore, there are ten wastewater treatment units. In this case, a total of 11 computing units are required, including 10 computing units and one computing unit at the monitoring center.
Equipment costs were very high. However, according to the above method , only one arithmetic unit needs to be installed in the monitoring center, so that the equipment cost is very low.

[0018]

The claim 1, according to the present invention, without using an expensive flow indicator integrated meter to measure the water amount of water discharged to calculate the COD emissions, measuring the inflow of raw water flowing into the oxidation ditch The output of the flow rate indicating integrator and the output of an inexpensive COD measuring device for measuring the COD of the discharged water can be input to the arithmetic unit, and the COD emission per 24 hours of the discharged water can be accurately obtained. In addition, the equipment cost is reduced because the use of one expensive flow rate integrator is eliminated. According to the second aspect, the computing unit for calculating the COD emission amount provided to one of the wastewater treatment apparatuses is abolished, and discharged from a plurality of OD type wastewater treatment apparatuses by one computing unit at the central monitoring center. COD emissions per 24 hours of water
It can be calculated and obtained for each D-type wastewater treatment device and can be centrally managed. In addition, the equipment cost is greatly reduced because a computing unit is not provided in each OD type wastewater treatment apparatus.

[Brief description of the drawings]

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

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

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

[Explanation of symbols]

DESCRIPTION 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 Discharge tank 18 Sludge storage tank 19 Flow rate integrator 20 COD measuring instrument 21 Control panel 22 Calculator (PC) 23 water quality measuring tank 30 OD type wastewater treatment equipment 31 monitoring center 32 computing unit (PC) 33 telephone network

Claims (2)

(57) [Claims] 1. A transferred raw water from the raw water tank to the oxidation ditch, and precipitation treatment transferred to settling tank after the raw water was aerated with oxidation ditch, further, or sedimentation tank
In an oxidation ditch type wastewater treatment device that discharges water through a disinfection tank, a flow indicator integrator that measures the inflow of raw water transferred from the raw water tank to the oxidation ditch, and a water quality measurement tank upstream of the disinfection tank or a disinfection tank A COD measuring device for measuring the COD value of water is provided in a downstream discharge flow path of the water , and the output of the water discharged per 24 hours by the output of the flow rate indicating integrator and the output of the COD measuring device is provided. An oxidation ditch type wastewater treatment apparatus comprising a calculator for calculating COD emissions. 2. A transferred raw water from the raw water tank to the oxidation ditch, and precipitation treatment transferred raw water in oxidation ditch to settler After aeration, disinfecting the settling tank
So as to discharge through the bath, said a flow indicator integrated meter for measuring the inflow of raw water is transferred to oxidation ditch from the raw water tank, upstream of the water quality measuring tank of disinfecting bath or disinfecting bath
A COD measuring device for measuring the COD value of water is provided in the discharge channel downstream of
Each of the plurality of oxidation-ditch type wastewater treatment apparatuses provided with a control panel to which the output of the D measuring device is input is connected to a central processing unit via a line, and each wastewater treatment apparatus is connected to the central processing unit. Centralized control method for an oxidation-ditch type wastewater treatment apparatus, comprising calculating a COD emission amount per 24 hours of water discharged from a wastewater treatment apparatus.