JPH11347308A - Apparatus and method for removing suspended solid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a suspended solid removing apparatus capable of easily and reliably removing SS components and iron compounds from raw water with changing quality and at the same time being simplified and manufactured at a low cost. SOLUTION: Proper amounts of a flocculant from a flocculant adding part 4 and a neutralizing agent from a neutralizing agent adding part 3 are respectively added to cancel the pH change in a prior stage to a treated pure water producing part 5 where raw water is stirred and mixed to flocculate suspended solid (SS), so that pH of raw water can be kept within a flocculation capable range of the flocculant in the treated pure water producing part 5 even raw water with changeable water quality and well water containing iron compounds. SS can easily and reliably be removed and no water quality inspection of raw water is required, so that the apparatus for removing SS itself can be simplified and the cost of the apparatus can be lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for removing suspended solids (Suspended Solid: SS component) contained in water to be purified, and more particularly to purification of water to be purified, whose water quality changes. To a suspended matter removing device.

[0002]

2. Description of the Related Art Conventionally, there is an apparatus of this type shown in FIG. FIG. 4 shows an overall block diagram of a conventional suspended matter removing apparatus. In FIG. 1, a conventional suspended solids removing apparatus includes a water intake section 1 for taking water from a river or the like as raw water, a coagulant adding section 4 for adding a coagulant to raw water taken from the water intake section 1, The raw water to which the flocculant has been added is stirred and mixed to aggregate the SS component, and the aggregated SS component is removed to generate a treated fresh water. And a neutralizing agent adding section 30 for adding the water.

Next, a description will be given of a cleaning operation of a conventional suspended matter removing apparatus based on the above configuration. First, the water from a river or the like is taken as raw water by the water supply unit 1, and the coagulant adding unit 4 adds a coagulant of polyaluminum chloride to the raw water in a predetermined amount. The raw water to which the polyaluminum chloride has been added is first stirred in the treated fresh water generating section 5 to aggregate the SS component, and then the aggregated SS component is separated by a method such as precipitation to become treated fresh water.

Since the pH of the treated fresh water is largely changed by the addition of polyaluminum chloride as a flocculant, the pH of the raw water is initially adjusted by adding a neutralizing agent of sodium hydroxide from a neutralizing agent adding section 30. Adjust to a value. The treated fresh water whose pH value has been adjusted in this way can be used for drinking, for irrigating agricultural crops, and the like.

[0005] As water for hydroponic cultivation, expensive tap water and well water are used in large quantities. For example, in the case of rose hydroponics, about 1 liter / day of water is supplied per rose, and 100,000 roses require a large amount of tap water or well water of about 100 t / day.

[0006]

SUMMARY OF THE INVENTION Since the conventional suspended solid removing apparatus is configured as described above, when raw water is taken from a river or the like, the water pollution degree of the raw water is determined in the rainy season, the dry season, or There is a problem that a sufficient aggregating action cannot be obtained even if a predetermined amount of the aggregating agent is uniformly added, because the state changes due to a change in the upstream condition or the like. That is, when the quality of raw water is poor and the degree of contamination is high, a larger amount of a flocculant must be added because of the large pH buffering capacity. On the other hand, when the raw water quality is not bad and the pollution degree is low, p
Since the H buffer capacity is small, a smaller amount of the flocculant is sufficient. Therefore, when a predetermined amount of coagulant is uniformly added, if the water quality of the raw water changes, a sufficient coagulation action cannot be obtained due to a difference in buffer capacity, and reliable purification cannot be performed.

[0007] The treated fresh water produced without obtaining such a sufficient coagulation action is in a state in which the SS component is uniformly finely dispersed to cause a Tyndall phenomenon. This SS
When the treated fresh water in which the components are finely dispersed is supplied as irrigation water to the hydroponic cultivation apparatus, a tube for supplying irrigation water (having a diameter of about 1)
mm) has a problem that clogging occurs. In order to grow and cultivate flowers such as rose trees with this hydroponic cultivation apparatus, the scale of the rose trees is generally 40,000 to 100,000. Will be arranged like a net. When the clogging of the tube such as the mesh of the net occurs, there is a problem that the supply of irrigation is stopped and flowers such as roses are withered.

In order to solve the problem of such a conventional suspended substance removing apparatus, there is another conventional suspended substance removing apparatus as shown in FIG. 5, and FIG. 5 shows another conventional suspended substance removing apparatus. FIG. 2 shows an overall block diagram of the removing apparatus. In this figure, the other conventional suspended matter removing apparatus includes a water intake unit 1, a flocculant adding unit 4, a treated fresh water generating unit 5, and a neutralizing agent adding unit 30 similarly to the suspended matter removing device shown in FIG. And a water quality inspection unit 6 for inspecting the quality of raw water taken from the water intake unit 1 in addition to the above configuration. Based on the inspection result of the water quality inspection unit 6, the coagulant addition unit 4 is provided. And the amount of addition of the neutralizing agent adding section 30 are controlled.

In this conventional suspended matter removing apparatus, an optimum coagulant (and a neutralizing agent) according to the quality of raw water is added, so that the SS component is sufficiently coagulated to ensure the SS component. Although it can be separated, there are problems that the configuration of the apparatus itself becomes complicated and that the addition amounts of the flocculant and the neutralizing agent must be precisely controlled. In particular, since there are various types of SS components, it is difficult for the water quality inspection unit 6 to accurately and quickly detect water quality, and since the water quality inspection unit 6 itself is expensive, the entire apparatus costs less. There is a problem of becoming high.

[0010] In addition, when this water is supplied by tap water, the cost of the water supply is borne, and when it is supplied by well water, the equipment cost for forming a well capable of pumping high quality fresh water is reduced. There was a problem that countermeasures against land subsidence would be a heavy burden. Especially in the case of well water
There are many cases in which harmful iron and salt are contained in cultivated crops, and it is said that it is extremely difficult to hit a well that produces good quality fresh water.

The present invention has been made in order to solve the above-mentioned problems, and can easily and surely remove SS components from raw water whose quality changes and well water containing iron, and can simplify and reduce the apparatus itself. It is an object of the present invention to provide an apparatus for removing suspended substances which can be manufactured at a low cost.

[0012]

According to the present invention, there is provided an apparatus for removing suspended solids, comprising: a coagulant adding section for adding a coagulant to raw water whose water quality changes according to a water intake timing; and a stirrer for the raw water to which the coagulant is added. And a treated water generating unit for producing a treated fresh water by aggregating the suspended material contained in the raw water to produce a treated fresh water, wherein the pH value of the raw water is changed by the flocculant added by the flocculant adding unit. Correspondingly, it has a neutralizing agent adding section for adding a neutralizing agent having a reverse change in pH value to raw water in the preceding stage of the treated fresh water generating section.

As described above, in the present invention, the coagulant from the coagulant addition section and the neutralization from the neutralizer addition section are provided before the treated fresh water generation section in which raw water is stirred and mixed to coagulate suspended substances. The amount of pH of the raw water within the coagulation range of the flocculant in the treated fresh water generation unit is also adjusted for the raw water whose water quality changes, since the amount of the agent added is such as to offset the pH change.
The value can be maintained, the SS component can be easily and reliably removed, and the water quality inspection of the raw water is not required, so that the apparatus itself can be simplified and the cost can be reduced. In particular, since the fertilizer component contained in the river water is not removed and is maintained as it is, when the water for hydroponic cultivation is generated, the amount of the fertilizer for cultivation can be suppressed to a small amount. Furthermore, since harmful iron content can be removed from cultivated crops, well water containing iron content can be saved.

In the apparatus for removing suspended solids according to the present invention, if necessary, the acidity / basicity of the flocculant and the neutralizing agent added from the neutralizing agent adding section and the flocculant adding section can be adjusted to about 3 bases. About 1 acid
Is the ratio of As described above, in the present invention, since the coagulant and the neutralizing agent are added at a ratio of about 1 acid to 1 acid / basic acid to about 3 bases, the SS component is more uniformly controlled. And iron can be removed.

The apparatus for removing suspended solids according to the present invention, if necessary, has a target p of treated fresh water generated from a treated fresh water generator.
The coagulant addition section and the neutralizer addition section adjust the addition amount of the coagulant and the neutralizer based on the H value. As described above, in the present invention, the addition amounts of the flocculant and the neutralizing agent are added based on the target pH value according to the use of the treated fresh water from which the SS component has been removed. Can be improved.

In the method for removing suspended solids according to the present invention, a flocculant is added to raw water whose water quality changes depending on the intake time, and the raw water to which the flocculant has been added is stirred to remove suspended solids contained in the raw water. In the method for removing suspended solids by coagulation to produce treated fresh water, a change in the pH value of the raw water caused by the added coagulant, and a change in the pH value of a neutralizer having a reverse characteristic is contained in the raw water. This is added to the raw water at the stage prior to the step of coagulating the suspended matter. As described above, in the present invention, the coagulant and the neutralizing agent are added in such amounts that the pH change is offset each other before the treatment step of coagulating the suspended substance by stirring and mixing the raw water. In addition, the raw water whose water quality changes can maintain the pH value of the raw water within the coagulation range of the flocculant in the treated fresh water generation section, and the SS component can be easily and reliably removed, and the water quality inspection of the raw water is not required. Therefore, the method itself can be simplified and the cost can be reduced.

In the method for removing suspended solids according to the present invention, the acid / base degree of the coagulant and the neutralizing agent to be added is a ratio of about 1 base to about 3 bases. As described above, in the present invention, the coagulant and the neutralizing agent are added at a ratio of about 1 acid to 1 acid / basic acid to about 3 bases. Components can be removed.

The apparatus for removing suspended solids according to the present invention adjusts the amounts of the flocculant and the neutralizer based on the target pH value of the treated fresh water to be produced, if necessary. As described above, in the present invention, the addition amounts of the flocculant and the neutralizing agent are added based on the target pH value according to the use of the treated fresh water from which the SS component has been removed. Can be improved.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An apparatus for removing suspended solids according to an embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is an overall block diagram of a suspended matter removing device according to the present embodiment, FIG. 2 is a pH change characteristic diagram by adding a neutralizing agent to raw water quality in the suspended matter removing device shown in FIG. 1, and FIG. FIG. 2 is an operation explanatory characteristic diagram of the suspended solid removing device illustrated in FIG. 1.

In each of the figures, the suspended matter removing apparatus according to the present embodiment includes a water intake section 1, a flocculant adding section 4, and a treated fresh water producing section 5 as in the conventional suspended matter removing apparatus shown in FIG. And neutralizing agent adding section 3 (corresponding to 30 in FIG. 4)
And the neutralizing agent adding section 3 is provided with a flocculant adding section 4
And the neutralizing agent adding section 3 substantially corresponds to the pH value change of the raw water due to the flocculant added from the flocculant adding section 4, and the change in the pH value adds a neutralizing agent having the opposite characteristic. It is a configuration to do.

The coagulant addition section 4 adds polyaluminum chloride as a coagulant, and the neutralizer addition section 3 adds sodium hydroxide as a neutralizer. The acidity / basicity of the added neutralizing agent and flocculant is such that sodium hydroxide has a ratio of about 3 bases and polyaluminum chloride has a ratio of about 1 acid.

The treated fresh water generator 5 includes a rapid stirring tank 51, a slow stirring tank 52,
In this configuration, the drift tank 53, the sedimentation tank 54, and the filtration tank 55 are arranged in this order. At the bottom of the settling tank 54, a drain 54a for discharging precipitated fine aggregates (hereinafter, floc) is provided. At the bottom of the filtration tank 55, filtered treated fresh water is supplied to a downstream equipment. This is a configuration in which an extraction pump 55a for supplying to the pump is provided.

Next, the SS of this embodiment based on the above configuration
Each operation of coagulation, removal, and filtration of components will be described. First, in the same manner as the above-mentioned conventional apparatus, water from a river or the like is taken as raw water by the water intake section 1, and the pH value of the raw water is generally included in the range of pH 6 to pH 8 unless there is an artificial effect such as pollution. It is a target.

In the range of pH 6 to pH 8,
The addition amount Gp of the coagulated polyaluminum chloride is set. When the set addition amount of polyaluminum chloride is added to raw water, the pH value of the raw water changes.
The pH is determined, and the added amount Gp of sodium hydroxide that offsets this ΔpH is set. When this sodium hydroxide is added to raw water as a neutralizing agent, for example, as shown in FIG. 2, the pH value of raw water having three types of water quality changes. In this figure, a case where 0.1 [cc] of sodium hydroxide and 0.1 [cc] of polyaluminum chloride of 1N concentration are added to 1 liter of raw water.

When the addition amount Gp of sodium hydroxide set in this way is added to the raw water from the neutralizing agent addition section 3, the pH value changes depending on the difference in the buffer capacity depending on the quality (contamination degree) of the raw water. In FIG. 3, it is assumed that the raw water taken from the water intake unit 1 is two types A and B, each having a pH of 6.5 and different water qualities. The raw water A has poor water quality and high turbidity, and the raw water B has good water quality and low turbidity. In this case, in FIG. 3, in the raw water A, the pH value is slightly changed (ΔpHA1) as shown by a broken line, whereas in the raw water B, the pH value is largely changed (ΔpHB1) as shown by a dashed line. Becomes

Further, the set addition amount Gp of the polyaluminum chloride is added from the coagulant adding section 4 to the raw water whose pH value has changed by adding sodium hydroxide. The raw water to which the coagulant has been added is treated water
Is transferred to the rapid stirring tank 51, and the rapid stirring tank 51 uniformly mixes the flocculant with the raw water by the rapid stirring operation.

The raw water in which the coagulant is uniformly mixed changes the pH value by a change amount according to the water quality. That is, in the case of the raw water A in FIG. 3, since the water quality is poor, the buffer capacity is large, and only a small pH value change (ΔpHA2) occurs. The change ΔpHA2 in the pH value is equal to the change ΔpHA1 in the pH value due to the addition of the sodium hydroxide. In the case of raw water B, the buffer capacity is small because of good water quality, and the pH value changes greatly (ΔpHB
2) will be done. This change in pH value ΔpHB2
Is equal to the change ΔpHB1 in the pH value due to the addition of the sodium hydroxide.

As described above, in the rapid stirring tank 51, the raw water A is indicated by a broken line, and the raw water B is indicated by a dashed line so that the initial pH value of the raw water taken in the water intake section 1 becomes substantially the same as the initial pH value. Will be displaced as follows. Therefore, regardless of the difference in the quality of the raw water, it is included in the initially set aggregation range of polyaluminum chloride, pH 6 to pH 8.

The coagulation range of this polyaluminum chloride is p
The raw water whose H value has been adjusted is transferred to the slow stirring tank 52,
In this slow stirring tank 52, a large floc is generated by the coagulation action of the polyaluminum chloride. The raw water in which the large flocs have been generated is deflected downward by the drift tank 53 and supplied from below the sedimentation tank 54.
At 4 the floc is precipitated and separated from the treated fresh water. The sedimented flocs are discharged at predetermined intervals or arbitrarily at a drain 54a disposed on the bottom surface of the sedimentation tank 54.

When the raw water contains iron, together with the floc generating action of the polyaluminum chloride, the iron is also removed as floc. The action of removing iron can be considered as follows. That is, aluminum and iron exist as +3 valent Al ³⁺ and Fe ³⁺ as stable ions. This +3 iron group ion is hydrolyzed around pH 6, and exists as a metal hydroxide.

Accordingly, iron is oxidized by oxygen in the air to become iron oxide (for example, fine particles such as red rust), and the iron oxide as the fine particles is aggregated as the SS component in the polyaluminum chloride to form flocs. In addition, aluminum and iron can exist as ions even in the +3 valence state, and since both form hydroxides having a similar structure, the floc generated by Fe ³⁺ of ionized iron is integrated. It becomes a flock that has been transformed.

As described above, it is possible to remove both the iron as iron oxide aggregated as flocs by the polyaluminum chloride and the iron that has been flocculated by Fe ³⁺ of ionized iron. Further, the treated fresh water from which the flocs have been separated is filtered by the filtration tank 55 to remove fine flocs and the like, and then the treated fresh water is supplied to the downstream equipment by the extraction pump 54a.

In the apparatus for removing suspended solids according to the above-described embodiment, the generated treated fresh water is configured to substantially match the initial pH value of the raw water that has been taken. Can be set to the required pH value. Further, in the suspended solid removing device according to the embodiment, the neutralizing agent adding section 3 is disposed in front of the flocculant adding section 4, and after the neutralizing agent sodium hydroxide, the flocculant polyaluminum chloride is added. Although the configuration is such that the neutralizing agent and the coagulant are added simultaneously or in the reverse order, they may be configured to be added.

[0034]

As described above, in the present invention, in the preceding stage of the treated fresh water generating section where raw water is stirred and mixed to aggregate suspended substances, the coagulant from the coagulant adding section and the neutralizing agent adding section The neutralizing agent is added only in an amount that offsets the pH change, so that the pH value of the raw water can be maintained within the flocculation range of the flocculant in the treated fresh water generation unit even for raw water that changes in water quality. Thus, the SS component can be easily and reliably removed, and the water quality inspection of the raw water is not required, so that the apparatus itself can be simplified and the cost can be reduced. In particular, since the fertilizer component contained in the river water is not removed and is maintained as it is, when the water for hydroponic cultivation is generated, the amount of the fertilizer for cultivation can be suppressed to a small amount.
Furthermore, since the harmful iron content of the cultivated crop can be removed, there is an effect that well water containing iron content can be saved. If necessary, the apparatus for removing suspended solids according to the present invention has an acid / base ratio of about 3 bases and about 1 base acid for the coagulant and the neutralizer added from the neutralizer addition section and the flocculant addition section. Is the ratio of Thus, in the present invention,
Since the coagulant and the neutralizing agent are added at a ratio of about 1 acid to about 3 bases, the SS component can be removed by more uniform control processing. Further, in the present invention, since the coagulant and the neutralizing agent are added in a ratio of about 1 acid to 1 base to about 3 acid, the SS component can be removed by more uniform control processing. It has the effect that it can be removed. Further, in the present invention, since the addition amounts of the flocculant and the neutralizing agent are added based on the target pH value according to the use of the treated fresh water from which the SS component has been removed, the use of the treated fresh water is easy. This has the effect that it can be improved. Further, in the present invention, in the first stage of the treatment step of aggregating suspended substances by stirring and mixing the raw water, the coagulant and the neutralizing agent are each added in such an amount as to offset the pH change. The raw water pH changes within the flocculation range of the flocculant in the treated fresh water generator even for raw water whose water quality changes
The value can be maintained, the SS component can be easily and reliably removed, and the method itself can be simplified and the cost can be reduced because the water quality inspection of the raw water is not required. In the present invention, since the coagulant and the neutralizing agent are added at a ratio of about 1 acid to about 3 bases in terms of acid and base, the SS component is more uniformly controlled. Can be removed. Also,
In the present invention, since the addition amounts of the flocculant and the neutralizing agent are added based on the target pH value according to the use of the treated fresh water from which the SS component has been removed, the usability of the treated fresh water is improved. It has the effect of being able to.

[Brief description of the drawings]

FIG. 1 is an overall block configuration diagram of a suspended solid removing apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a pH change characteristic of a raw material water quality by adding a neutralizing agent in the suspended solid removing apparatus shown in FIG. 1;

FIG. 3 is an operation explanatory characteristic diagram of the suspended solid removing apparatus shown in FIG. 1;

FIG. 4 is an overall block configuration diagram of a conventional suspended matter removing device.

FIG. 5 is an overall block configuration diagram of another conventional suspended matter removing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Water intake part 3, 30 Neutralizer addition part 4 Coagulant addition part 4 5 Treated fresh water generation part 6 Water quality inspection part 6 51 Rapid stirring tank 52 Slow stirring tank 53 Deviation tank 54 Precipitation tank 54a Drain 55 Filtration tank 55a Extraction pump

Claims (6)

[Claims] 1. A flocculant adding section for adding a flocculant to raw water whose water quality changes according to a water intake timing, and aggregating a suspended substance contained in the raw water by stirring the raw water to which the flocculant is added. A suspended solid removing device comprising a treated fresh water producing unit for producing fresh water, wherein the flocculant adding unit corresponds to a pH value change of raw water due to the flocculant added, and the pH value change is a neutralizing agent having a reverse characteristic. And a neutralizing agent adding section for adding to a raw water in a stage preceding the treated fresh water generating section. 2. The apparatus for removing suspended matter according to claim 1, wherein the acid / base degree of the coagulant and the neutralizer added from the neutralizer addition section and the coagulant addition section is about 3 bases. An apparatus for removing suspended solids, wherein the ratio of acid is about 1. 3. The apparatus for removing suspended solids according to claim 1, wherein a target pH of the treated fresh water generated from the treated fresh water generator is set.
An apparatus for removing suspended solids, wherein an addition amount of a coagulant and a neutralizer is adjusted based on a value of the coagulant and the neutralizer. 4. A flocculant for adding a flocculant to raw water whose water quality changes depending on the time of water intake, stirring the raw water to which the flocculant has been added, and coagulating suspended substances contained in the raw water to produce treated fresh water. In the method for removing suspended substances, the method corresponds to a change in pH value of raw water due to the added flocculant,
A method for removing suspended substances, comprising adding a neutralizing agent having a reverse pH value to a raw water in a stage prior to the step of aggregating suspended substances contained in the raw water. 5. The method for removing a suspended substance according to claim 4, wherein the acid / basicity of the coagulant and the neutralizing agent to be added is a ratio of about 1 base to about 3 bases. A method for removing suspended solids. 6. The method for removing suspended solids according to claim 4, wherein the amounts of the coagulant and the neutralizing agent are adjusted based on a target pH value of the generated treated fresh water. To remove suspended solids.