JP2556309B2 - Suspended water treatment method and flocculant treatment device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a suspension water treatment method and a flocculant treatment apparatus, and particularly to rapid agitation, slow agitation, sedimentation basin or flotation separation basin of raw water of waterworks in particular. The present invention relates to a treatment method in which flocs to be produced in a rapid stirring tank are separately prepared and added.

2. Description of the Related Art Water treatment methods for removing pollutants from polluted water in which pollutants are suspended to purify them are used in various fields. For example, raw water from waterworks is first introduced into a rapid stirring tank to inject a coagulant, and the raw water and the coagulant are mixed by stirring. This causes the coagulant such as PAC (polyaluminum chloride) to undergo hydrolysis,
Form flock. The flocs are introduced together with the raw water into the slow stirring tank in the next step, where the pollutants of the raw water are brought into contact with the flocs, and the pollutants are adsorbed. Then, the flocs that have adsorbed the pollutants are cross-linked and guided to the settling basin together with the raw water, where they are left standing and separated by sedimentation.

Since such water treatment of tap water is carried out by continuously introducing raw water, the time for which the raw water stays in the rapid stirring tank is also limited, and within this limited time, hydrolysis of the flocculant and formation of flocs are performed. It is preferable that it is performed sufficiently. However, for example, the rate of hydrolysis of flocculant PAC and the formation of flocs vary depending on the concentration, stirring conditions, alkalinity, coexisting ions, temperature, PH, etc. If it is sent to the agitation tank together with the raw water, the pollutants in the raw water are not sufficiently absorbed by the flocs, and if they are sent to the sedimentation basin as it is, the pollutants that are not adsorbed by the flocs remain in the water without settling. Removal efficiency of pollutants becomes poor,
The supernatant liquid taken out may not be suitable as drinking water. In order to avoid this, it is necessary to control the concentration of the above coagulant, etc., depending on the state of raw water, but since the raw water may be treated differently during the summer and in the current period, the actual conditions may differ. It is annoying to control it. In this case, the water treatment rate may be reduced to facilitate floc formation of the flocculant in any raw water, but this is not preferable because it lowers the water treatment efficiency. Especially when treating raw water with low water temperature in winter, hydration reaction such as hydrolysis of flocculant and formation of flocs are less likely to occur. .

The above was the case where the pollutant was separated by sedimentation, but it is also possible to carry out the suspension separation of the suspended matter like the flotation, and in such a suspension separation method, for example, the coagulant is added by the same steps as above. After treatment, the floating separation pond is used instead of the sedimentation pond to agglomerate the suspension, and when the agglomerated particles are floated and separated by, for example, air bubbles, there are similar problems regarding the efficient use of the aggregating agent. .

Problems to be Solved by the Invention As described above, since the flocculant in the conventional water treatment was added directly to the water to be treated, the hydration reaction and the floc generation efficiency were improved when the continuous water treatment was performed. Poorly, in this bad state, contact with the suspended solids of the water to be treated was prevented, and there was a problem in terms of the efficiency of sedimentation separation or floating separation.

Means for Solving the Problems In order to solve the above problems, the present invention has a step of treating water to be treated with a flocculant together with a flocculant in a stirring tank to form a suspended substance in the water to be treated. In the water treatment method of sedimentation separation or floating separation, the whole or a part of the coagulant added to the water to be treated is treated with a part of the water to be treated in a flocculant treatment tank having a smaller volume than the stirring tank. The present invention provides a method for treating suspended water, which comprises forming flocs and / or intermediates thereof and adding the formed flocs and / or intermediates to the water to be treated in the stirring tank.

In addition, in a water treatment method of treating water to be treated together with a flocculant in a stirring tank to form flocs, a flocculating agent added to the water to be treated in a water treatment method in which suspended solids in the water to be treated are separated by sedimentation or floatation. Is treated with a part of the water to be treated in a flocculant treatment tank having a volume smaller than that of the stirring tank, and a suspendable substance or the separated pollutant during the treatment of the flocculant. Is added to form a floc and / or an intermediate thereof, and the formed floc and / or an intermediate thereof is added to the water to be treated in the stirring tank. It is a thing.

In addition, a flocculant treatment tank for forming a floc and / or an intermediate thereof by stirring and mixing various instruments and at least water and a flocculant among floc forming elements of water, a flocculant, a neutralizer, and a suspendable substance. And at least water, a floc-forming element of the flocculant and a transportation means for transporting the floc and / or an intermediate thereof, and at least flocculates the floc-forming element of the water and the flocculant based on the values measured by the various instruments. Disclosed is a flocculant treatment apparatus characterized in that flocs and / or intermediates thereof are formed by treatment in an agent treatment tank and the flocs and / or intermediates thereof can be delivered.

Action If the coagulant is treated with water and a small volume treatment tank, the concentration of the coagulant can be increased and the formation of flocs and intermediates can be promoted. Therefore, a small volume of a system different from that for treating water to be treated is used. When flocs and their intermediates are formed in the treatment tank and added to the water to be treated, the flocs can be efficiently formed in the water to be treated. At this time, the suspended substance is added during the formation of the flocs. And this becomes a nucleus and makes it easy to make flocs. Further, the flocculant processing device can be unitized as an auxiliary device.

Example Next, an example of the present invention will be described.

In FIG. 1, reference numeral 1 is a water treatment tank, and this water treatment tank 1 has a rapid stirring tank 2, a slow stirring tank 3, and a settling tank 4, and the rapid stirring tank 2 and the slow stirring tank 3 are respectively stirred. Machines 2a and 3a are provided, and a settling tank 4 is provided with a heat panel 4a having a heater coated with ceramic at each water depth at the entrance. A flocculant treatment device 5 capable of supplying flocculant flocculant and / or an intermediate thereof to the water treatment tank 1 is provided.

This coagulant treatment device 5 pumps water from a raw water storage tank 8 by a pump 7 and introduces this water into a line mixer 13 through a flow meter 9, a densitometer 10, a thermometer 11, and an alkalinity meter 12 in this order. . Air is blown into the line mixer 13 from the blower 14 by the compressor 15,
From the acid-based coagulant tank 16, PAC, sulfuric acid band, iron sulfate, iron chloride, and other inorganic coagulants are pumped 17, and from the polymer coagulant tank 18, polyacrylamide, alginic acid,
A high-molecular flocculant such as starch is injected by a pump 19, and a part of the raw water and these flocculants are stirred by air and sent to a flocculant treatment tank 20, where the first agitating chamber 20a from the sedimentation tank 4 is used. A part of sludge is injected by the sludge injection pump 21 and stirred by the mixer 21a. Next, in the second stirring chamber 20b, a neutralizing agent such as NaOH and Ca (OH) ₂ is injected from the neutralizing agent tank 22 by the pump 23, stirred by the mixer 21b to cause overflow, and further the third stirring chamber 20c, the fourth stirring chamber 20c. In the stirring chamber 20d, the mixers 21c and 21d are sequentially stirred to cause overflow, and the PH meter
After passing through the densitometer 25 and the densitometer 25, a transfer pump 26 injects it into the ascending rapid stirring tank 2.

In order to perform continuous water treatment of waterworks in such a configuration, the flocculant treatment device 5 is operated in a state where raw water containing pollutant as a suspended substance has flowed in according to a usual treatment method. Thereby, the pumping amount of the pump 7 is controlled so that the flow rate of a part of the raw water is measured and the coagulant injected into the rapid stirring tank 2 becomes a predetermined amount. The turbidity, temperature, and alkalinity of a part of the raw water whose flow rate is determined in this way are measured, and the injection amount of the acid-based coagulant and the polymer coagulant for a part of the raw water is determined based on the measured values. Is dispersed in the line mixer 13 and sent to the first stirring chamber 20a of the flocculant treatment tank 20, where sludge is injected and stirred so as to have a predetermined concentration with reference to the turbidity, and then the second stirring chamber At 20d, refer to the above alkalinity to match the injection amount of the acid-based coagulant, and inject a neutralizer so as to make it neutral, and stir.
After that, stirring is performed in the third stirring chamber 20c and the fourth stirring chamber 20d. In this way, the flocculant is agitated with part of the raw water,
The acid-based flocculant is hydrolyzed, and the metal hydroxide forms various polymers to form flocs serving as a flocculation nucleus, which is placed in a neutral state.

At this time, if the temperature of the water to which the flocculant is added is raised, the production rate of flocs and intermediates thereof also increases. For example, regarding the effect of this temperature, when the temperature drops from 24 ° C to 0 ° C, the formation rate of flocs becomes 30% slower, and at 4.4 ° C or lower and 21 ° C or higher, the required amount of coagulant increases more than at the intermediate water temperature. There are experimental results. The removal rate of plankton coagulation and precipitation when aluminum sulfate and clay were used as coagulants was 52% at 5 ° C, 80% at 20 ° C and 96% at 30 ° C.
% Experimental results have been obtained. From these points, the temperature of the water to which the coagulant is added is, for example, 4 to 40 ° C. in practical use,
This is not a limitation.

Here, the formed flocs may be injected into the rapid agitation tank 2, but an intermediate, that is, a hydration reaction product such as a hydrolyzate and a product that reaches the subsequent flocs are injected into the rapid agitation tank 2. Is desirable. This is the dispersion of coagulant,
The quality of collision between particles greatly influences the agglomeration effect.The hydrolysis of the salt-type aggregating agent is extremely fast, and the activity of the product decreases with time. It is necessary to do so.

Specifically, for example, assuming that the coagulant concentration in the treated water of 60 m ^{3 in} the rapid stirring tank is 20 ppm, the coagulant concentration is 1200 ppm in the coagulant treatment tank of 1 m ³ and this is added to the treated water of 60 m ^3. The coagulant concentration of 1200 ppm is far higher in the formation rate of flocs and their intermediates.
When the coagulant is treated in a small-capacity treatment tank in this way, stirring immediately after pouring the coagulant into water is extremely important, but this can be done.The higher the stirring speed, the better, but this stirring time can be increased. It is easy to control mechanical conditions that can efficiently perform stirring, such as that it can be shortened, and that when a line mixer is used together with air bubbles as described above, the turbulent flow effect can be improved and the stirring effect can be improved. Dispersion is achieved, and the dispersed materials come into contact with each other and collide with each other to easily form flocs and intermediates thereof. Also, the flocculant concentration in water has an optimum range for forming flocs, but this can also be easily controlled. Also, similarly
Control of pH, alkalinity, water temperature, and coexisting substances can be facilitated.

When added to the rapid stirring tank 2 as described above and stirred here, flocs and intermediates thereof are dispersed and mixed with the water to be treated and contact with polluted particles is achieved. When sent to 3, the flocs adsorb pollutants and crosslink them. This is sent to the settling basin 4 and settles and separates when it is left standing. At this time, since the water is heated by the heat panel 4a, the viscosity of water is reduced and solid-liquid separation is easily performed.In addition, the convection is suppressed because there is no temperature difference between the water depths, and the agitation of pollutants is suppressed, and the adsorbed on the flocs. The polluted substances are naturally and efficiently settled to obtain clear water. This is sent to a sterilization tank (not shown) and used as drinking water. Part of the sedimented pollutants is returned to the first stirring chamber 20a of the flocculant treatment tank 20.

The water treatment is carried out in this way, but flocs of the coagulant and / or intermediates thereof are prepared in advance in the coagulant treatment apparatus 5 and added to the raw water of the water to be treated introduced into the rapid stirring tank 2. In the rapid agitation tank 2, it is only necessary to mix the raw water with the already prepared flocs and / or intermediates thereof, and this mixing is performed quickly, so that the time can be shortened. This can reduce the volume of the rapid stirring tank 2 and shorten the residence time. Also, by injecting a part of sludge into raw water together with flocs,
When the pollutant concentration of raw water is low, the pollutants and sludge come into contact with each other, and these are absorbed by the flocs to enhance the sedimentation efficiency. At this time, when the temperature of the water to be treated is raised in the rapid stirring tank 2 and the slow stirring tank 3, the viscosity of the water becomes low, so-called solid-liquid separation from the pollutant becomes easy, and the floc of the flocculant is brought into contact with the water. Is promoted and its trapping efficiency is improved.

The pumps that pump up part of the raw water, the coagulant, the neutralizer, and the amount of sludge injected can be controlled manually by visually observing each instrument, but the indicator values for each instrument are managed by a computer, and Based on the amount of water to be treated based on the above, it is possible to control a part of these raw water, the mixing amount of the flocculant, the floc concentration, the amount of flocs delivered to the rapid stirring tank, and the like.

In the above, the coagulant was injected into the line mixer 13, but the first
A part or all of the stirring chamber 20a may be injected, and in the latter case, the line mixer can be omitted.

In the following, part of the water to be treated was used as the water to mix the coagulant, but in order to better form flocs, a heater was used in the coagulant treatment tank, steam was blown in, and a serpentine tube through which steam was passed was used. The temperature may be raised by immersing or by converting heat of sunlight by a solar plate or the like.

Although the floc and the intermediate thereof are formed by the coagulant treatment apparatus 5 in the above, a method of forming the floc by injecting the coagulant into the conventional rapid stirring tank 2 can be used together.

Also, the above uses sludge from the settling basin and prevents sludge from entering from anything other than that based on raw water.
Suspended substances such as silica, other sludges, fibers and the like can also be used with or instead of this sludge.

In the above, the pollutant was settled, but the flocculating agent used in the case of suspending suspended matter by air using a floating separation tank instead of the sedimentation tank of the same device as above is also the same as above. Can be used.

The aggregating agent may be used in combination as described above,
It can be used alone.

EFFECTS OF THE INVENTION As described above, according to the present invention, the flocculant and the intermediate thereof are formed by treating the coagulant with a part of the water to be treated in the treatment tank having a small volume. By increasing the concentration of the coagulant, the stirring efficiency is good, and the hydration rate of its hydrolysis, etc., the floc formation rate, etc. are fast. It can be carried out efficiently even when the water content is low, and by treating the coagulant with a part of the water to be treated, the suspended solids serve as nuclei to facilitate the formation of flocs and further promote their formation. In addition, it is possible to easily control various factors when performing the treatment, and it is possible to produce a desired constant quality of flocs and intermediate products.

In this way, flocs of constant quality and intermediates thereof can be obtained efficiently and easily, so this can be simply mixed with the water to be treated, and a state in which the flocs are uniformly dispersed in the water to be treated can be quickly obtained. In the case of continuous water treatment, particularly when the water treatment rate is high, it is possible to enhance the efficiency of the suspended substance adsorption of the flocculant. In addition, when a suspendable substance such as sludge is used together with a flocculant, it becomes a nucleus of the growth of this floc, and a new suspended substance adheres to the suspended substance of the water to be treated with a low suspended substance concentration. It is preferable because it enhances the aggregation effect. When the coagulant is intensively treated in a small volume in this way, it is easy to control it, so it is possible to change the temperature, pH, suspended substance concentration, etc. of the water to be treated as in the conventional method. Hydrolysis of flocculants and flocs are not hindered, so the water treatment efficiency does not change significantly depending on the condition of the water to be treated, especially in winter when coagulants are slow to hydrolyze and flocs are formed slowly. Water treatment efficiency can be improved. Further, when the coagulant is treated and added to the water to be treated in this manner, the efficiency is higher than that of the treatment directly with the water to be treated, and therefore the volume of the rapid stirring tank in the case of water treatment of water supply can be reduced. Therefore, the volume of the sedimentation basin can be increased, and the amount of the coagulant used can be reduced.
In this way, a great advantage can be given to the water treatment efficiency of the apparatus and the cost can be reduced. In addition, since the coagulant treatment device can be provided, if it is used as a unitary accessory device, its versatility can be enhanced.

[Brief description of drawings]

The figure is a schematic illustration of an apparatus for carrying out the method of one embodiment of the present invention. In the figure, 2 is a rapid stirring tank, 4 is a sedimentation tank, 5 is a coagulant treatment device, 7,17,19,26 are pumps, 9 is a flow meter, 10 is a turbidimeter, 11
Is a thermometer, 12 is an alkalinity meter, 24 is a pH meter, 25 is a thermometer, and 20 is a flocculant treatment tank.

Claims (3)

(57) [Claims] 1. A water treatment method comprising a step of treating water to be treated together with a coagulant in a stirring tank to form flocs, and settling or floating separation of a suspended substance in the water to be treated,
All or part of the flocculant added to the water to be treated is treated with a part of the water to be treated in a flocculant treatment tank having a smaller volume than the stirring tank to form flocs and / or intermediates thereof,
A method for treating suspended water, characterized in that the formed flocs and / or intermediates thereof are added to the water to be treated in the stirring tank. 2. A water treatment method comprising the step of forming flocs with treated water in a stirring tank together with a flocculant, wherein the suspended matter in the water to be treated is separated by sedimentation or flotation.
All or part of the flocculant added to the water to be treated can be treated with a part of the water to be treated in a flocculant treatment tank with a smaller volume than the stirring tank, and can be suspended during the treatment of this flocculant. Flock and / or by adding a part of the substance or the separated pollutant
Or an intermediate thereof, and the formed floc and / or
Alternatively, an intermediate thereof is added to the water to be treated in the stirring tank, which is a method for treating suspended water. 3. An agglomerate which forms a floc and / or an intermediate thereof by stirring and mixing at least water and an aggregating agent among various instruments and water, an aggregating agent, a neutralizing agent, and a block forming element of a suspendable substance. An agent treatment tank and a transportation means for transporting at least water, a floc forming element for the flocculant and the floc and / or an intermediate thereof, and at least water, floc formation for the flocculant based on the values measured by the various instruments. A flocculant treatment apparatus characterized in that the element is treated in the flocculant treatment tank to form flocs and / or intermediates thereof, and the flocs and / or intermediates can be delivered.