JPS5998710A - Water treatment system of water purification plant - Google Patents

Abstract

PURPOSE:To conserve the consumption amount of a flocculant and to efficiently make use of the water treatment of a water purification plant while rapidly corresponding to the fluctuation of a water demand amount, by injecting the flocculant into the inflow raw water of the water purification plant corresponding to the water quality of said raw water. CONSTITUTION:When inflow raw water discharged from a water arrival basin 10 reaches a predetermined turbidity value of more in the water quality thereof, the inflow raw water discharged from the water arrival basin #10 is supplied to a chemical agent mixing basin 12 where a predetermined amount of a flocculant is injected to perform water treatment. On the other hand, when the inflow raw water discharged from the water arrival basin #10 reaches the predetermined turbidity value or less in the water quality thereof, the gate of a change-over gate 30 is changed over by the control signal from a flocculant injection control apparatus 34 and the inflow raw water discharged from the water arrival basin #10 is supplied to a filter basin 26 through a bypass pipe 32.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a water treatment system for a water treatment plant, and in particular, a flocculant is injected into the raw water flowing into the water treatment plant depending on the quality of the raw water flowing into the water treatment plant, and water treatment in a filtration pond is performed. The present invention relates to a water treatment system for a water purification plant that is suitable for efficiently performing water treatment.

[Prior art]

In the conventional water treatment system for a water purification plant, as shown in FIG. 1, raw water flowing into the water purification plant is first guided to the landing water #lO, and then supplied to the chemical mixing pond 12 from the landing water #lO. The water quality of the raw water flowing into the water purification plant supplied to landing water #10 is measured by a water quality meter 14, and the flow rate of the raw water flowing into the water purification plant is measured by a flow meter 16. Water quality meter 14, flow meter 1
The outputs of 6 are each supplied to the flocculant injection control device 18, and the flocculant injection control device 18 calculates the flocculant injection portion from the water quality and inflow amount of raw water flowing into the water purification plant. Furthermore, the flocculant injection control device 18 controls the flocculant injection section 20 to inject a flocculant into the chemical mixing pond 12 according to the calculated value.

The raw water flowing into the water purification plant into which the coagulant has been injected is supplied from the chemical mixing tank 12 to the settling tank 24 via the flocculation tank 22 . The turbidity contained in the raw water flowing into the water purification plant into which the flocculant has been injected becomes flocs in the flocculant by the action of the flocculant in the flocculant, and is settled and removed in the settling basin . That is, even if the inflow raw water from the water treatment plant is supplied as is to the settling tank 24, the suspended matter contained in the inflow raw water, which has a negative ion charge on its surface, only undergoes Brownian motion and does not settle. Therefore, a flocculant is injected using ten ions to form flocs in which the suspended solids are combined with each other, thereby making it easier for the suspended solids to settle.

The suspended solids that are settled and removed in the settling tank 24 are filtered out by the filter oil 26, and the inflow raw water with low turbidity is supplied to the water purification tank 28.

In the case of the system shown in FIG. 1, most of the turbidity contained in the raw water flowing into the water treatment plant is settled and removed in the sedimentation tank 24, so the burden of water quality treatment in the filtered oil 26 is reduced, and the filter The cleaning process in the oil passage 26 can be performed efficiently.

By the way, in System K, the flocculant is injected at an amount that corresponds to the turbidity of the inflowing raw water, but when the turbidity of the inflowing raw water is 1°C, the turbidity necessary for the formation of flocs is The quality decreases, making it difficult for suspended solids to settle.

Therefore, in conventional systems, even when the turbidity of the inflow raw water is low, in order to make the suspended solids easy to settle,
Control was performed to increase the amount of coagulant injected. However, increasing the amount of coagulant to be injected when the turbidity of the inflow raw water is low will result in the coagulant being wasted.

On the other hand, when the turbidity of the inflowing raw water is low due to the increase in the amount of coagulant, the turbidity becomes flocs and is settled and removed in the settling tank 24, but a part of the increased amount is not settled in the settling tank 24 and is filtered out. The oil is supplied to the oil passage 26. This means that, from the side of the filtered oil 26, the amount of inflow of substances that cause clogging of the filtered oil 26 increases.

Therefore, a system using a floc recycling method has been proposed in which the sludge stored in the filtered oil 26 is returned to the chemical mixing pond 12 when the turbidity of the inflowing raw water is low.

In this system, when the turbidity of the inflowing raw water is low, the sludge stored in the filter oil 26 is returned, so when the turbidity of the inflowing raw water is low, the turbidity settles without increasing the amount of flocculant injection. The flocculant is not wasted.

However, even in the case of a system based on the floc recycling method, the raw water flowing into the water purification plant is configured to be supplied to the filtration oil 26 via the settling tank 24, so if the water demand of the water purification plant fluctuates, the water demand Therefore, it was difficult to efficiently operate water treatment at water treatment plants. That is, the treatment time of the inflow raw water in the chemical mixing pond 12, the flocculation pond 22, and the filtered oil 26 is several minutes, but the treatment time of the inflow raw water in the settling tank 24 is several hours, e.g. It takes about 8 hours.

For this reason, in conventional systems that supply inflow raw water to the sedimentation tank 24 even when the turbidity of the inflow raw water is low, the treatment time for the inflow raw water is long, and the system does not respond to fluctuations in the amount of water demanded. cannot be processed quickly.

Another option is to stop the injection of flocculant when the turbidity of the inflowing raw water is low, but even with this method, if the water demand changes, water treatment at the water treatment plant may be necessary, similar to the system of the floc recycling method. It is difficult to operate the system efficiently.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to reduce the amount of coagulant consumed and to efficiently operate water treatment at a water treatment plant. The purpose is to provide a processing system.・ [Summary of the Invention] In order to achieve the above object, the present invention provides an inflow raw water bypass passage that bypasses the sedimentation tank and supplies the raw water that flows into the water treatment plant to the filtered oil, and also reduces the amount of raw water that flows into the water treatment plant. When the quality of the raw water flowing into the water treatment plant is below a predetermined turbidity, the injection of the coagulant is stopped, and the supply of the raw water flowing into the water treatment plant to the settling tank is switched to the supply to the raw water bypass supply path. [Embodiments of the Invention] Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

FIG. 2 shows the configuration of a preferred embodiment of the invention.

The system in this embodiment has a configuration of a coagulant injection unit that calculates the amount of coagulant to be injected from the water quality and inflow amount of the raw water flowing into the water treatment plant, and injects the flocculant into the raw water flowing into the water treatment plant according to the calculated value. In addition to being different from the system shown in Figure 1, water landing #1
A switching gate 22 is provided in the inflow raw water supply path that supplies the inflow raw water of 0 to the chemical mixture 12, and further constitutes an inflow raw water bypass path that bypasses the settling tank 24 and supplies the water purification plant inflow raw water to the filtered oil 26. The system differs from the system shown in FIG. 1 in that an inflow raw water bypass pipe 32 is provided, but the other configurations are the same as the system shown in FIG. Therefore, their explanation will be omitted.

The system in this embodiment supplies the inflow raw water discharged from the landing water #10 to the chemical mixing pond 12 when the water quality of the inflow raw water discharged from the landing water #10 has a predetermined turbidity or higher; By injecting a predetermined amount of flocculant, a treatment similar to that of the G-stem shown in FIG. 1 is performed.

On the other hand, when the quality of the inflowing raw water discharged from landing water #10 becomes below the predetermined turbidity, the flocculant injection control device 34
The switching gate 30 is configured to switch the gate of the switching gate 30 in response to a control signal from the inflow water #10, and supply the inflow raw water discharged from the landing water #10 to the filtration oil 26 via the inflow pipe 32.

The above control is performed by the flocculant injection control device 34, and in this embodiment, the water quality of the inflowing raw water is judged by turbidity and alkalinity, so the water quality meter 36 is equipped with a turbidity meter and an alkalinity meter. The flocculant injection control device 34 is configured as follows.

That is, as shown in FIG. 3, the flocculant injection control device 34 includes a flocculant injection rate calculation circuit 40, a flocculant injection amount setting circuit 42, a sludge generation amount calculation device 44, and a gate switching circuit 46.
, and an inhibition circuit 48.

The output of the alkalinity meter 50 installed in the water quality meter 36 is supplied to the flocculant injection rate calculation circuit 40, and the output of the turbidity meter 52 is supplied to the flocculant injection rate calculation circuit 40 and the sludge generation amount calculation device 44. has been done. Coagulant injection rate calculation circuit 40Fi
To calculate the optimal flocculant injection rate, use an alkalinity meter 5.
0 output and the output of the turbidity meter 52, calculate the optimal injection rate γ for turbidity using alkalinity as a parameter,
The optimum flocculant injection rate signal is sent to the flocculant injection amount setting circuit 42.
supply to.

In addition, in the flocculant injection rate calculation circuit 40, when the alkalinity of the inflow raw water is high, the flocculant injection rate becomes high;
When the alkalinity is low, the flocculant injection rate is calculated to be low.

The flocculant injection amount setting circuit 42 calculates the flocculant injection amount from the flocculant injection rate signal and the output of the flow meter 16, and supplies the flocculant injection amount signal to the sludge generation amount calculation device 44 and the inhibition circuit 48. .

On the other hand, the sludge generation amount calculation device 44 takes in the outputs of the turbidity meter 52 and the flowmeter 16 and the flocculant injection amount signal, and determines whether the quality of the inflowing raw water has become below a predetermined turbidity with respect to the inflowing amount of the raw water flowing into the water treatment plant. The amount of sludge is calculated to determine whether This sludge amount T is determined based on the following first equation.

T=aIITuBkQ+β* (1−・−・・−・(1
) where α: sludge generation coefficient for turbidity TUB: turbidity Q: flow rate β: sludge generation coefficient for flocculant q: flocculant injection amount The sludge amount T calculated by the sludge generation amount calculation device 44 has a predetermined turbidity. When the amount of sludge generation is below, an output signal is supplied from the sludge generation amount calculation device 44 to the gate switching circuit 46, the gate switching circuit 46 switches the gate of the switching gate 30, and the inflowing raw water discharged from landing water #10 bypasses the inflowing raw water. It is supplied to the filtered oil 2 and 6 via a pipe 32.

Further, at this time, the inhibition circuit 48 is activated by the output signal from the gate switching circuit 46, and the injection of the flocculant by the flocculant injector 20 is stopped.

As described above, in this embodiment, since the injection of the flocculant is stopped when the turbidity of the inflowing raw water is low, it is possible to save the flocculant and to reduce the burden on the oil to be filtered. Furthermore, when the turbidity of the inflow raw water is low, the inflow raw water bypasses the settling tank and is supplied to the filtered oil, so even if the demand water volume changes, it is possible to quickly respond to the change in the demand water volume.

〔Effect of the invention〕

As explained above, according to the present invention, injection of the flocculant is stopped when the water quality of the inflowing raw water relative to the amount of inflowing water to the water treatment plant is less than a predetermined turbidity, and the inflowing raw water to the water treatment plant flows through the settling tank. Since the water is bypassed and supplied to the filtration channel, it is possible to save on the amount of coagulant consumed, and it is also possible to quickly respond to fluctuations in water demand, allowing for efficient water treatment at the water treatment plant. It has excellent effects.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a conventional system, FIG. 2 is a configuration diagram of a system showing an embodiment of the present invention, and FIG. 3 is a configuration diagram for explaining the configuration of the flocculant injection section shown in FIG. 2. Melt. 10... Water landing #, 12... Chemical mixing pond, 14.36
...Water quality meter, 16...Flow meter, 18.34...
Coagulant injection control device, 24...Sedimentation tank, 26...Water oil passage, 30...Switching gate, 32...Inflow raw water bypass pipe. Country 2nd port

Claims (1)

[Claims] 1. # Injection of flocculant i' based on the quality and amount of inflow raw water
A flocculant injection unit calculates ff:fi and injects a flocculant into raw water flowing into the water treatment plant according to this calculated value, and the raw water flowing into the water treatment plant into which the flocculant has been injected is supplied, and the turbidity contained in this raw water is supplied. In a water treatment system for a water purification plant, the system includes a sedimentation basin that removes Iti substances by floc sedimentation, and a filtration basin that removes Iti substances contained in the inflow water by a 31 m filter. It has an inflow raw water bypass path for supplying to the filtration basin, and the flocculant injection part stops injecting the flocculant when the water quality of the inflow raw water is less than a predetermined turbidity with respect to the inflow amount of the water treatment plant inflow raw water, and a water treatment system for a water purification plant, the feature of which is to switch the supply of inflow raw water from the water purification plant to the sedimentation tank to the supply to the inflow raw water bypass supply path.