JPS62294488A - Treatment of aqueous suspension - Google Patents

Abstract

PURPOSE:To enhance floc forming efficiency, by raising the temp. of a part or all of water to be treated introduced into a stirring tank and subsequently adding a part or all of a flocculant to said water to be treated. CONSTITUTION:Raw water is made to flow to a rapid stirring tank 2 and a ceramic heater is brought to an operation state to raise the temp. of raw water to 14-25 deg.C. An inorg. flocculant, an org. flocculant and a neutralizing agent are injected in the rapid stirring tank 2 from an inorg. flocculant tank 5, an org. flocculant tank 6 and a neutralizing agent tank 7 so as to adjust the concns. of said additives to predetermined values. The flocculants rapidly cause hydration reaction by heated water and grow to form flocs. The raw water mixed with flocs is sent to a slow speed stirring tank 3 to be stirred and allowed to stand to perform solid-liquid separation. By this method, treatment time can be shortened.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention Industrial Field of Application The present invention relates to a method for treating suspended water, and in particular, it relates to a method for treating suspended water, particularly raw water of waterworks, etc., by rapid agitation, slow agitation, settling tank or flotation separation of oil. The present invention relates to a treatment method in which the hydrolysis of a flocculant and the generation efficiency of flocs in a rapid stirring tank are improved in a treatment method in which treatment is performed sequentially in a rapid stirring tank.

2. Description of the Related Art Water treatment methods for purifying pollutants by removing pollutants from suspended water are used in various fields.

For example, raw water from a city water supply is first introduced into a rapid stirring layer, a flocculant is injected, and the raw water and flocculant are stirred and mixed.

This causes the flocculant, such as PAC (polyaluminum chloride), to undergo hydrolysis and form flocs. This floc is led to the next step, a slow stirring tank, along with the raw water.
Here, the pollutants in the raw water are brought into contact with the flocs, the pollutants are adsorbed onto the flocs, and the flocs are crosslinked.

The flocs that have adsorbed the pollutants are then crosslinked and led together with the raw water to a sedimentation tank where they are allowed to stand still and are sedimented and separated.

Such water treatment for waterworks is carried out continuously while introducing raw water, so the time the raw water stays in the rapid stirring tank is also limited, and within this limited time, the hydrolysis of the coagulant and the formation of flocs are completed. Preferably, this is done thoroughly. However, for example, the hydrolysis of the flocculant PAC and the rate of floc formation vary depending on its concentration, stirring conditions, alkalinity, coexisting ions, temperature, pH, etc.
If the raw water is sent to the slow stirring tank with insufficient floc formation, the pollutants in the raw water will not be sufficiently adsorbed by the flocs. Since the pollutants are left in the water without sedimentation, the removal efficiency of pollutants becomes poor, and the supernatant liquid that is removed may not be passable as drinking water.

To avoid this, the concentration of the above-mentioned flocculant must be controlled according to the condition of the raw water, but the conditions in which raw water is treated may differ, such as the temperature being different in winter and summer IJI. Therefore, it is actually troublesome to control it. In this case, it may be possible to reduce the water treatment rate to facilitate the formation of coagulant flocs.
This is undesirable because it lowers the water treatment 'dJ rate. Particularly when treating raw water with a low water temperature in winter, it is difficult to hydrolyze the coagulant and form flocs, which reduces the water treatment speed and increases costs, and improvements are desired.

”-The description was for the case where pollutants are separated by sedimentation, but it is similar to flotation! ! ! Floating separation of suspended matter is also practiced, and in such a floating separation method, for example, after treating the flocculant with a process similar to the above, the suspended matter is flocculated using floating separation oil instead of a sedimentation tank. Similar problems regarding the efficient use of flocculants arise when the flocculants are allowed to build up and the flocculated particles are floated off, for example by air bubbles.

Problems to be Solved by the Invention As explained above, in conventional water treatment, flocculants are added directly to the water to be treated, so when continuous water treatment is performed, hydrolysis and floc formation efficiency is poor. Since the water to be treated comes into contact with suspended solids in this poor condition, there is a problem in terms of sedimentation separation or flotation separation efficiency, and an improvement has been desired.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention includes a step of treating the water to be treated in a stirring tank to form flocs together with a coagulant. In a water treatment method in which substances are separated by sedimentation or flotation, the temperature of some or all of the water to be treated introduced into a stirring tank is raised, and part or all of a flocculant is added to the water to be treated whose temperature has been raised. The present invention provides a method for treating suspended water characterized by:

In addition, in a water treatment method that includes a process of treating water to be treated to form flocs together with a flocculant in a stirring tank, and in which suspended solids in the water to be treated are separated by sedimentation or flotation, the water to be treated is introduced into the stirring tank. The temperature of some or all of the water is increased, and part or all of the flocculant is added to the heated water to be treated, and during the treatment of this flocculant! This invention provides a method for treating suspended water, which comprises adding a turbidable substance or a part of the above-described separated suspended substance.

In addition, in a water treatment method that includes a process of treating water to be treated to form flocs together with a flocculant in a stirring tank, and in which suspended solids in the water to be treated are separated by sedimentation or flotation, the water to be treated is introduced into the stirring tank. Eliminate the temperature difference at each water depth in the process of increasing the temperature of some or all of the water, adding some or all of the flocculant to the heated water, and separating the suspended solids by sedimentation or flotation. The present invention provides a method for treating suspended water characterized by the following.

When the flocculant is treated with water at a higher temperature than the water to be treated, the hydration reaction such as hydrolysis of the flocculant is promoted, and the formation of flocs is promoted.

At this time, if 1f'N of agglomerated suspendable material is added, it becomes a nucleus for the formation of flocs and facilitates the formation of flocs. Furthermore, if the pollutants adsorbed on the flocs are allowed to settle in a place where there is no temperature difference, convection is suppressed and the settling efficiency can be increased.

Example Next, one embodiment of the present invention will be described.

In Figure 1, ■ is a water treatment tank, and this water treatment [1 has a rapid stirring tank 2, a slow stirring tank 3, a sedimentation tank 4 7, a rapid tIj,
The stirring tank 2 and the slow stirring tank 3 are provided with agitators 2a and 3a, respectively, and the sedimentation tank 4 is provided with a droop panel 4a having a heater coated with ceramic at each water depth at the entrance.

In the rapid stirring tank 2, as shown in FIG. 2, a ceramic heater 2b, such as an electric heater coated with ceramic, is installed as a heating body around the stirrer 2a, and the above-mentioned A portion of the settled sludge is returned to the rapid stirring tank 2 from the bottom of the settling tank 4.

Further, 5 is an inorganic #: gauze agent tank such as PAC, 6 is an organic flocculant tank such as polyacrylamide, and 7 is a neutralizer tank for adjusting PI+.

In order to perform continuous water treatment for water supply in such a configuration, the raw water must be treated at 60r+ according to an appropriate treatment method.
? 600 tons per hour is poured into the rapid stirring tank 2, the ceramic heater 2b is activated to bring the water temperature to 14 to 25°C, and the ceramic heater 2b is filled with an inorganic thread coagulant tank 5, an organic coagulant tank 6, The neutralizing agent is injected from the tank 7 so that the concentration in the rapid stirring tank 2 is, for example, 2 ppm, and a part of the sludge in the settling tank 4 is injected so that the concentration in the rapid stirring tank 2 is, for example, several ppm. inject.

In this way, warmed water (for example, 14-25℃)
For example, the temperature is several degrees to several tens of degrees higher than the raw water), the flocculants PAC and polyacrylamide rapidly undergo a hydration reaction, which grows to form flocs. For example, acid-based flocculants are hydrolyzed, and metal hydroxides form various polymers to form flocs that serve as flocculation nuclei, but these hydrolysis and floc formation are promoted. The sludge added at this time, which forms the core of the flocs, assists in the formation of flocs.

Increasing the temperature of the water to which the flocculant is added in this way increases the rate of formation of flocs and their intermediates.

For example, experimental results show that when the water temperature drops from 24°C to 0°C, the rate of floc formation slows down by 30%;
There is data that shows that at water temperatures below and above 21°C, the required amount of flocculant increases compared to when the water temperature is between these temperatures.

Furthermore, when aluminum sulfate and clay were used as flocculants, the plankton flocculation sedimentation removal rate was 52 at 5°C.
%, 80% at 20°C and 96% at 30'C. From these points, the temperature of the water to which the flocculant is added is practically exemplified as 4 to 40°C, but is not limited to this.

The raw water mixed with flocculant flocs as described above is sent to the slow stirring tank 3 and stirred by the stirrer 3a to ensure sufficient contact with the pollutants in the raw water. In this state, the water to be treated is sent to the sedimentation tank 4, and when it is left standing there, the water to be treated is heated by the heat panel 4a, reducing the viscosity of the water and facilitating solid-liquid separation. Since there is no temperature difference, convection is suppressed and agitation of pollutants is suppressed, and the pollutants adsorbed on the flocs are efficiently allowed to settle naturally, resulting in clear water. This is sent to a sterilization tank (not shown) and made into drinking water.

Water treatment is carried out in this way, but since the water to be treated in the rapid stirring tank 2 is warmed, the hydration reaction of the flocculant and the formation of flocs are promoted and the production efficiency is high. The time required to generate flocculant flocs within 2 can be shortened. This makes it possible to reduce the volume of the rapid stirring tank 2 and to shorten the water treatment time.

At this time, when the contaminant concentration of the raw water is low, a part of the teta mud added to the flocculant increases the frequency of contact with contaminants and coagulates, and these are absorbed by flocs, increasing their sedimentation efficiency. At this time, when the temperature of the water to be treated is increased in the rapid a stirring tank 2, the slow stirring tank 3, and further the settling tank 4,
The viscosity of water becomes lower, so-called solid-liquid separation between pollutants and water becomes easier, and the contact of the flocculant with the flocs is promoted, improving the trapping efficiency.

Although a ceramic heater is used in the above example, a surrounding wall 8 may be provided around the stirrer 2a as shown in FIG. As shown in FIG. 4, a flexible pipe 10 through which heated steam passes may be provided around the stirrer 2a.

In addition, as shown in Figure 5, the rapid stirring tank 2 is connected to the solar plate 1).
It is also possible to set up a solar house and configure it like a solar house to utilize solar heat.

In addition, although the above method uses sludge from a settling tank to prevent sludge from entering from sources other than raw water, suspended substances such as kaolin, silica, other sludge, and fibers can also be used together with or in place of this sludge. .

Further, although the flocculant was added to the heated water in the above example, a conventional method of adding the flocculant to a rapid stirring tank can also be used in combination with the method of the present invention.

Examples of flocculants include inorganic flocculants such as PAC, hunt sulfate, iron acid, and iron chloride, and organic flocculants such as polyacrylamide, alginic acid, and starch; examples of neutralizing agents include N a O1), An example is Ca(OH).

In the above method, the pollutants were settled, but the above also describes the flocculant used when using a similar device to the above, using floating separation oil instead of a sedimentation tank, and separating the suspended substances with air. It can be used in the same way.

Effects of the Invention As explained above, according to the present invention, since the flocculant is treated by heating the water to be treated, the hydration reaction of the flocculant and the formation of flocs are promoted, and when continuous water treatment is carried out, Especially when the water treatment rate is high, the pollutant adsorption efficiency of the flocculant can be increased. At this time, it is preferable to use a suspended substance such as sludge together with a flocculant, as this will serve as a nucleus for the growth of the floc and will also enhance the effect of flocculating the pollutants in the water to be treated, which has a low concentration of pollutants. When the treatment of the flocculant is slowed down in this way, the hydration reaction of the flocculant and the formation of flocs are less likely to be hindered by the temperature of the water to be treated, the PH1 pollution concentration, etc. The treatment efficiency is high (there is no change, and the water treatment efficiency can be greatly improved, especially in winter when the hydration reaction of the flocculant and the formation of flocs are slow.In addition, in this way, the flocculant generation efficiency is If this is good, the volume of the rapid stirring tank can be reduced, for example in the case of water treatment for waterworks, and the volume of the sedimentation tank can be correspondingly increased, and the amount of flocculant used can be reduced.In this way, on the equipment, It can provide a large advantage in water treatment efficiency and reduce costs.

[Brief explanation of drawings]

FIG. 1 is a schematic process explanatory diagram of a method according to an embodiment of the present invention, and FIGS. 2 to 5 are schematic diagrams each showing a means for warming the water to be treated in a rapid stirring tank. In the figure, 1 is a water treatment tank, 2 is a rapid stirring tank, 3 is a slow stirring tank, 4 is a sedimentation tank, 2a is a stirrer, and 2b is a ceramic heater. Figure 3 To Figure 2 Figure 5 Solar heat ↓↓↓

Claims (3)

[Claims] (1) In a water treatment method that includes a step of treating water to be treated to form flocs together with a flocculant in a stirring tank, and in which suspended solids in the water to be treated are separated by sedimentation or flotation, the treated water is introduced into the stirring tank. A method for treating suspended water, which comprises increasing the temperature of some or all of the treated water and adding some or all of a flocculant to the heated water. (2) In a water treatment method that includes a step of treating water to be treated to form flocs together with a flocculant in a stirring tank, and separating suspended solids in the water to be treated by sedimentation or flotation, the treated water is introduced into the stirring tank. A part or all of a flocculant is added to the heated water to be treated by increasing the temperature of a part or all of the treated water, and when the flocculant is treated, suspendable substances or the above-mentioned separated suspended substances are added. A method for treating suspended water characterized by adding a part of. (3) In a water treatment method that includes a step of treating water to be treated to form flocs together with a flocculant in a stirring tank, and separating suspended solids in the water to be treated by sedimentation or flotation, the water introduced into the stirring tank is The temperature difference at each water depth in the process of increasing the temperature of some or all of the treated water, adding some or all of the flocculant to the heated water, and separating the suspended solids by sedimentation or flotation. A method for treating suspended water, characterized in that it eliminates the problem.