JP3030024B1 - Raw water treatment equipment - Google Patents

Abstract

Abstract: PROBLEM TO BE SOLVED: To suppress turbidity below a certain level by pretreatment of raw water even if raw water of a general river temporarily becomes ultra-high turbidity, and use a moving bed sand filtration device to reduce the turbidity to several degrees or less. A raw water treatment apparatus capable of supplying industrial water or simple tap water having a turbidity of SOLUTION: In a raw water treatment apparatus, a primary flocculant injection means 4 is connected to a feed line 2 for feeding raw water W from a water intake means 1a.
The secondary flocculant injection means 7 is connected to a feed line 5 for performing a sedimentation process to a turbidity of ~ 150 degrees or less and sending the secondary raw water,
The secondary raw water into which the secondary flocculant has been injected is transferred to the moving bed sand filter 6
To obtain treated water having a turbidity of several degrees or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for removing suspended pollutants from ultra-high turbidity raw water using a flocculant and a flocculant, and using a continuous moving bed sand filter to remove treated water having a turbidity of a certain level or less. It relates to a raw water treatment device that can be obtained.

[0002]

2. Description of the Related Art In a water purification plant that removes suspended pollutants and the like from raw water using river water as a water source and sends out drinking water and industrial water, the turbid concentration (hereinafter abbreviated as turbidity) of the raw water is 1000 to 2000. Necessary facilities are provided so as to be able to process even to the degree. Such water purification plant equipment roughly removes sand and mud contained in the raw water in a sand basin, and then guides it to a landing well to inject chemicals such as coagulant and coagulant, and the chemicals quickly enter this raw water. Mix rapidly in mixing ponds to spread and mix.

[0003] Next, when raw water is sent to a floc formation pond, it is gently stirred there to promote the transition to floc.
Suspended pollutants are coagulated and settled in a sedimentation basin directly connected to the floc forming pond to obtain purified water. In such a facility, a flocculation pond, a sedimentation pond, a treatment section requiring a large-scale and large site having a capacity for 5 to 6 hours of the treated water amount, a landing well, a mixing pond, a floc formation pond, and a sedimentation pond. Advanced metering equipment is provided for drug injection and concentration control.

[0004] In addition to such general water purification plant equipment, as an equipment for treating raw water using small-scale rivers, dam reservoirs, and underflow water, etc., having a small basin area, an upward flow type continuous moving bed sand filter is used. Is also becoming widespread as a facility mainly used for simple water supply or industrial water supply nationwide. In the case of the above-mentioned specific water source, the maximum turbidity is often less than 100 degrees throughout the year, and the above-mentioned filtration device is installed under such conditions, the drug is easy to inject, and the direct filtration method by micro floc is used. It is equipment that can treat raw water turbidity up to 100 to 150 degrees. Such a filtering device is known, for example, from JP-A-52-111062.

[0005]

The above-mentioned general water purification plant using river water as a water source has a very high turbidity (2).
(2000-2000 degrees), but it is equipped with equipment that can treat even raw water, but as described above, it requires a vast site to install facilities such as floc formation ponds and sedimentation ponds, and advanced instrumentation equipment Therefore, the construction cost is extremely high, and the maintenance of the equipment is very troublesome.

On the other hand, an "upflow type continuous moving bed sand filter"
Is a condition for installation that the raw water turbidity is 100 to 150 degrees or less, and it is not necessary to provide this as equipment equivalent to a general water purification plant that supplies drinking water. Even if used for simple water supply or industrial water supply, only one year
Even if there is only ultra-high turbidity on the order of 0 days, it cannot be used even when using raw water with ultra-high turbidity (200 to 2000 degrees), whose raw water turbidity far exceeds the installation conditions.

[0007] However, this facility has some very remarkable advantages in that the site required for installation is small, and therefore the facility cost is, of course, not as expensive as a general water purification plant and the control of injection of chemicals is simple. Therefore, if it can be improved to be usable even in ultra-high turbidity, these remarkable advantages can be utilized. However, there is no research data on how the turbidity changes when river water suddenly increases due to a typhoon or torrential rain, and the state of change until the ultra-high turbidity raw water returns to the normal state is well understood. Not.

The inventors of the present invention have investigated and analyzed the change in turbidity of river water during ultra-high turbidity in an actual river. It has been found that there is a characteristic that it rapidly decreases, and various types of water can be used for the water source of the above-mentioned moving bed filtration device even if the river water has an extremely high turbidity by using such a characteristic. As a result of the experiment and the invention, the raw water treatment apparatus of the present invention was proposed.

In view of the above circumstances, the present invention uses raw water from a general river as a water source and suppresses the turbidity to a certain level or less by pretreating the raw water even if the raw water temporarily becomes ultra-high turbidity. It is another object of the present invention to provide a raw water treatment apparatus capable of supplying industrial water having a turbidity of several degrees or less, water supply, and simple tap water using a moving bed sand filtration apparatus.

[0010]

According to the present invention, as a means for solving the above-mentioned problems, a primary flocculant for presenting raw water taken from a water intake means to a downstream and injecting a primary flocculant into a feed line is provided. Injection means is connected, the secondary raw water is led to a sand basin, and a secondary flocculant is injected into a feed line for sending raw water coarsely settled to a turbidity of 100 to 150 degrees or less in the sand basin downstream. An agent injection means was connected, and the secondary raw water was guided to a moving bed sand filter, and the raw water was treated by this filter to obtain treated water.

In the raw water treatment apparatus of the present invention thus configured, the turbidity and concentrated torrential rain rapidly increase water in a short period of time, and the turbidity concentration (hereinafter, abbreviated as turbidity) is extremely high (200 to turbidity).
(2000 degrees) can be used as raw water. When installing such a raw water treatment device, although not explicitly shown in the above configuration, generally, turbidity in each treatment step is detected as necessary,
When it is detected that the turbidity of the raw water taken in by the water intake means is higher than 150 degrees, the primary coagulant injection means is operated.

In this primary coagulant injecting means, a necessary main coagulant is injected according to the degree that the raw water turbidity is extremely high at 2000 degrees or low at about 200 degrees. Alkaline chemicals and coagulation aids are injected to adjust the PH value. By such a primary coagulant injection treatment, the turbidity of the raw water is pretreated to 100 to 150 degrees or less.

The significance of the pretreatment with the primary flocculant can be understood from the investigation and analysis graph of the change in turbidity of raw water shown in FIG. As shown in the figure, when the river water level suddenly rises from about 1.5 m to about 2.5 m due to the torrential rainfall after 2:00 am, the turbidity becomes as shown at analysis points A _{1 to} A _5. Changes rapidly. While river levels Analyzing point A ₁ has skyrocketed, but not yet turbidity suddenly increased is.

[0014] However, increased Analyzing point A ₂ turbidity until instantaneously sharply about 200 degrees, is rapidly reduced below 100 ° within one hour as a short time. After that, suddenly 1
After turbidity exceeding 00 degrees is increased, decreased sharply, even a decrease in turbidity and the analysis point A ₃ turbidity is about up to 100 degrees has become gentle, A _4, the A ₅ Turbidity The tendency for the decrease to be slower is even greater.

From the results of such analysis, it can be seen that river water having an extremely high turbidity generally has an extremely high turbidity, but the turbidity decreases only within a short time. Judging from the characteristics of the change, it is possible to rapidly change the turbidity within a short time by injecting a flocculant even in river water with extremely high turbidity. It can be used as raw water for the equipment.

In the raw water into which the chemical has been injected by the above-mentioned primary flocculant injection means, ultra-high turbidity pollutants contained in the raw water are removed in a sand basin, and the secondary water having a turbidity of 100 to 150 degrees or less is removed. The raw water is sent through a feed line. In the middle of the feed line, a chemical is further injected by a secondary flocculant injecting means, and the raw water is sent to a moving bed sand filter, which is used for once. Before and after treated water is obtained.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an overall schematic configuration diagram of a raw water treatment apparatus according to an embodiment. Reference numeral 1 denotes a general river, and its cross section is shown. Raw water W flowing through the river 1 is taken in by an intake pump 1p from an intake port 1a provided as an intake means, and is sent downstream by a feed line 2. The raw water W in the feed line 2 is sent to a sand basin 3, and a primary coagulant injection means 4 is connected in the middle of the feed line 2.

The primary coagulant injection means 4 includes a primary coagulant injection device 4a and a primary coagulation aid injection device 4b. The injection devices 4a and 4b may be of the same type,
Although the tanks may be of different types, the tank for storing the medicine is generally the former having a larger capacity than the latter. There are various types of injection devices 4a and 4b, such as a gravity drop type, a displacement type, a double orifice type, a saturator type, and an injection pump type, and any of them may be used. In this example, an injection pump type is used. Is used, and a drug can be forcibly injected by a pump.

Examples of the coagulant include widely used sodium sulfate and a solution of a metal salt containing aluminum, iron, zinc, tin and the like.
Metal salts containing iron, sodium, and the like are alkaline chemicals, and are used as pH adjusters to adjust the PH value in raw water. The coagulant is, for example, bentonite, sodium silicate, activated silicic acid, sodium alginate, etc., and is used to strengthen flocs and promote sedimentation.
It is to be noted that sodium sulfate may be used as the main coagulant, and the above alkaline chemicals may be used in parallel instead of the coagulation aid.

The sedimentation basin 3 is provided as a pond having a capacity of about one hour of the treated water amount in total with the filtration pump well 3a provided adjacent thereto, and is about １ ／ of the conventional sedimentation basin. It has a small capacity and a small site area. The filtration pump well 3a is a small well for overflowing and storing raw water from which suspended pollutants have been removed in the sedimentation basin 3, and is provided with a filtration pump 3p.

The raw water pumped up by the filtration pump 3p is sent to a moving bed sand filtration device 6 through a feed line 5, and a secondary flocculant injection means 7 is connected to the feed line 5 as well. Has exactly the same configuration as the primary coagulant injection means 4, and similarly has a secondary coagulant injection device 7a and a secondary coagulation auxiliary agent injection device 7b.

As shown in FIG. 2, the moving bed sand filtration device 6 feeds raw water from the feed line 5 to a raw water receiver 61 provided on the outer periphery of the lower bottom of a main body 60 having a cylindrical shape and a lower portion constricted in an inverted conical shape. The raw water receiver 61 has a lower end communicating therewith and a number of inlet pipes 62 inserted upward from the lower bottom of the main body 60. Immediately above the upper end thereof, a raw water dispersion plate 63s is provided to provide filtration in the main body 60. Filter raw water while preventing clogging with sand S
Distribute evenly to the whole area and permeate the gap of the filtered sand S with upward flow,
By passing through, the pollutants are removed and collected as clear filtered water in the weir 65b. The filter sand has a particle size of 0.8 to 1.2 mmφ and is filled to a height of about 1 m (about the lower half of the main body).

At the center of the main body 60, an air lift pipe 64 extending from the upper end to near the lower bottom is provided. An air blow pipe 64 inserted below the air lift pipe 64 is provided.
A compressed air is blown into a from an air pump (not shown), and the air, water and filtered sand rise in the mixed state while being vigorously stirred. Therefore, the filtered sand S capturing the pollutants toward the lower end of the air lift pipe 64 continuously gathers from the surroundings and is sucked into the air lift pipe 64.

The filter sand S mixed and stirred in the air lift tube 64 is cleaned by removing contaminants adhering to its surface. Filter sand S that has been primarily washed by air lift pipe 64
Are separated from the washing drainage in the washing water trough 65a, and fall downward while being dispersed by the labyrinth mechanism 67 in the sand washer 66 provided as secondary washing means. At this time, the water level difference ΔH between the filtered water surface and the washing drainage surface
As a result, a part of the filtered water rises in the sand washer 66 and flows upward in counterflow with the sand, so that the filtered sand S is washed again.

The flow rate of the washing water is set by adjusting ΔH so that the sand flows downward and the turbid substance flows upward. The filter sand S is completely returned to cleanness by the secondary washing, falls from the sand washer 66, and is evenly dispersed in the filter layer by the filter sand dispersion umbrella 63g.
The raw water is filtered again. Cleaning drainage is cleaning water trough 6
Drained from 5a to the outside. As described above, since the filter sand S is always kept in a clean state, it is possible to continuously perform filtration. The amount of washing wastewater varies depending on the concentration of raw water turbidity, but is usually about 10% of the amount of raw water.

The clarified water obtained by filtering the raw water W by the moving bed sand filtration device 6 having the above-described configuration and function is stored in the water receiving tank 8, and if necessary, not shown in the drawing, but is supplied by a water supply pump. Piped home.

In the raw water treatment apparatus of the embodiment having the above-described configuration, the turbidity of the raw water taken in from the water intake 121a is constantly checked by a sensor. In the illustrated example, although not explicitly shown, in each of the feed line 2, the settling basin 3, the filtration pump well 3a, the feed line 5, and the feed line 9 for sending the raw water sent from the moving bed sand filtration device 6, Raw water turbidity is automatically detected and recorded.

When the turbidity of the raw water exceeds 100 degrees in the feed line 2, the injection pump of the primary flocculant injecting means 4 is activated as required by the detection signal, and the main flocculant,
The alkaline chemical or the coagulation aid is sent out in a required amount according to the degree of turbidity. The required injection amount of the drug is determined in advance in accordance with the turbidity, and the set amount is sent out.

The raw water W into which the chemical is injected is sent to the sand basin 3 through the feed line 2, where the chemical is sufficiently dispersed and settled by the stirring means. As a result, the turbidity of the raw water from which suspended pollutants have been removed in the sand basin 3 is 1
It is necessary to set the above-mentioned preset amount of medicine injection so as to be not more than 00 to 150 degrees. For example, by injecting a primary flocculant around 100 mg / l and a flocculant (alkaline agent) around 10 mg / l, it is possible to treat raw water of 1000 degrees or more to 100 to 150 degrees or less.

The raw water thus treated has a turbidity of 100.
Because it is processed to ~ 150 degrees or less, filtration pump 3p
The raw water of this turbidity is sent out through the feed line 5 because the conditions for sending the raw water of this turbidity to the moving bed sand filtration device 6 in the subsequent process are set. it can.

In the feed line 5, a secondary flocculant, a secondary alkali agent or a secondary flocculant is injected by a secondary flocculant injecting means. As described above, the treated water is obtained.

Although the raw water treatment apparatus according to the above embodiment is mainly an apparatus for supplying industrial tap water, water supply, or simple tap water, its use can be applied to various kinds of similar treatment apparatuses.

[0033]

As described above in detail, the raw water treatment apparatus according to the present invention is subjected to primary coagulation treatment of raw water taken in from a general river by a primary coagulant injection means, even if it has an extremely high turbidity.
After the turbidity is reduced to 100 to 150 degrees or less, the raw water is treated by a secondary flocculant injecting means and subjected to secondary flocculation, and the turbidity is reduced to several degrees or less by a moving bed sand filter. Even in the case of river water whose ultra-turbidity is only about 10 days throughout the year due to heavy rain, for example, at the time of ultra-high turbidity, this is pre-processed to a turbidity of a predetermined level or less, and treated water of a few degrees or less is produced by a filtration device. It can provide industrial water, water supply and treated water for simple water supply without the need for large-scale and extensive premises and equipment, such as general water purification plants, equipment, and instrumentation equipment. An extremely remarkable effect of being able to obtain.

[Brief description of the drawings]

FIG. 1 is an overall schematic view of a raw water treatment apparatus according to an embodiment.

FIG. 2 is a main sectional view of a moving bed sand filter.

FIG. 3 is a partially enlarged sectional view of the above.

FIG. 4 is a diagram showing a measurement graph of turbidity change of raw water of a river.

[Explanation of symbols]

 Reference Signs List 1 river 2 feed line 3 sedimentation basin 4 primary flocculant injecting means 4a primary flocculant injecting device 4b primary flocculant auxiliary injecting device 5 feed line 6 moving bed sand filtration device 7 secondary flocculant injecting means 7a 2 Secondary coagulant injection device 7b Secondary coagulant auxiliary agent injection device 8 Water receiving tank

Continuation of front page (56) References JP-A-10-71305 (JP, A) JP-A-5-284578 (JP, A) JP-A-56-5180 (JP, A) JP-A-55-137085 (JP, A) , A) JP-A-52-111062 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B01D 36/04 B01D 37/00 B01D 21/00-21/34 B01D 24/00 -24/48

Claims (4)

(57) [Claims] 1. A primary flocculant injecting means for feeding raw water taken from a river water intake means to a downstream and injecting a primary flocculant into a feed line, connecting the raw water to a sand basin, and feeding the raw water to a sand basin. A secondary flocculant injecting means for injecting a secondary flocculant is connected to a feed line for sending the secondary raw water coarsely settled to a turbidity of 100 to 150 degrees or less downstream, and the secondary raw water is transferred to a moving bed sand filter. A raw water treatment apparatus configured to obtain treated water by performing filtration treatment with the filtration apparatus. 2. The method according to claim 1, wherein the primary coagulant injecting means has a turbidity of 200 to 200.
Turbidity of 100 to 1 for 2,000 degree super high turbidity raw water
The raw water treatment apparatus according to claim 1, wherein an amount of the primary flocculant capable of performing the flocculation treatment at 50 degrees or less is supplied. 3. The primary flocculant injecting means comprises a primary flocculant injecting device for injecting a main flocculant and a primary flocculant injecting device for injecting an alkaline chemical or a flocculant. The raw water treatment device according to claim 1. 4. The moving bed sand filtration device fills a filter sand into a tubular device main body, and provides a raw water inflow pipe inside the device body from a lower bottom to an upper part to flow secondary raw water upward into the filter sand. An air lift pipe extending from the lower bottom to the vicinity of the upper end is provided in the main body of the device, and compressed air is sent upward from the outside through a blowing pipe connected near the lower end to filter from the lower end. Primary washing means for sucking sand and secondary raw water and mixing with compressed air to wash the filtered sand, and secondary washing for washing the filtered sand falling from the upper end of the airlift pipe outward from the upper end thereof in an upward facing flow. The raw water treatment apparatus according to any one of claims 1 to 3, further comprising means.