JP2006272121A - Starting-up method of water treatment apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To quickly start up a water treatment apparatus in which raw water containing inorganic contaminant ions is reacted with an insolubilizing agent insolubilizing the inorganic contaminant ions to form insoluble matter, and to obtain sludge containing the insoluble matter and separated water by solid/liquid separation of the insoluble matter. <P>SOLUTION: In this starting-up method of the water treatment apparatus, prior to supply of the raw water to a reactor, the water treatment apparatus is filled with water, a compound containing inorganic contaminant ion sources is added to the reactor, and the insolubilizing agent is added to a mixing tank and water in the water treatment apparatus is circulated by operating a sludge returning means, and when the insoluble matter in a solid/liquid separating tank has reached a given amount, the addition of the compound is stopped, and supply of the raw water to the reactor is started. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

In the present invention, raw water containing inorganic pollutant ions is reacted with an insolubilizing agent that insolubilizes the inorganic pollutant ions to form an insoluble matter, which is solid-liquid separated to obtain sludge containing the insoluble matter and separated water. The present invention relates to a method for starting up a water treatment apparatus.

In the treatment of raw water containing metal ions, an alkali is added to the raw water in the reaction tank to form an insoluble metal hydroxide, which is solid-liquid separated in the precipitation tank, and the separated water is discharged as treated water, There is a method of dewatering and disposing of sludge containing hydroxide insolubles. At that time, there is also a method of promoting insolubilization by returning the sludge containing the insoluble matter of the metal hydroxide separated into solid and liquid to the reaction tank.

In addition, as a method of obtaining highly concentrated metal hydroxide sludge that is rich in concentration and excellent in dewaterability, sludge containing metal hydroxide that has been separated into solid and liquid is mixed with alkali in advance, and the mixture is added to raw water There is an alkali sludge method (cited reference 1: Japanese Patent Publication No. 61-156).
In this alkaline sludge process, in order to stably obtain sludge with high concentration and excellent dewaterability, in order to maintain good quality of treated water, the amount of insoluble matter (SS amount) generated by neutralization of raw water and return sludge It is necessary to maintain the ratio of quantities within a certain range.
Therefore, the present applicant has proposed a method for treating heavy metal-containing wastewater in which the solid content of the returned sludge mixed with alkali is 15 to 40 times the amount of insolubilized product produced by the reaction of alkali and raw water. (Cited document 2: JP-A-5-57292).

In the case of raw water containing fluoride ions and phosphate ions, insoluble substances are generated using calcium compounds such as slaked lime and calcium chloride as insolubilizing agents as insolubilizing agents, and this is solid-liquid separated in a precipitation tank, There is a method in which the separated water is discharged as treated water, and sludge containing insoluble matter of calcium fluoride and calcium phosphate is dehydrated and disposed of. At that time, there is also a method of promoting insolubilization by returning sludge containing insoluble matter separated into solid and liquid to the reaction tank.

In addition, as a method of obtaining sludge containing calcium fluoride and calcium phosphate insoluble matter, which is rich in concentration and excellent in dehydration, solid-liquid separated calcium fluoride and calcium phosphate can be obtained without adding an insolubilizer directly to the raw water. After mixing sludge containing insoluble matter with alkali beforehand,
There is a method of adding the mixture to raw water (Cited Document 3: Japanese Patent No. 3457013, Cited Document 4: Japanese Patent No. 3468907). Also in this method, it is necessary to maintain the ratio of the insoluble matter (SS amount) generated from raw water and the amount of returned sludge in a certain range, as in the above-described alkaline sludge method.
Japanese Patent Publication No. 61-156 Japanese Patent Laid-Open No. 5-57292 Japanese Patent No. 3457013 Japanese Patent No. 3468907

However, in order to start up a water treatment apparatus for carrying out the above method to a steady state, it takes a start-up period of two weeks to one month, and during that time, treated water with a predetermined water quality cannot be obtained. There was a problem, how quickly the water treatment device was started up. In other words, normally, when a new water treatment device is installed, it is rare that raw water with a predetermined amount of water and a predetermined pollutant concentration is discharged from the beginning. Insoluble matter could not be accumulated in the tank, and it took a long time to start up the water treatment device.

Therefore, the present invention first fills the water treatment device, then adds a compound containing an inorganic pollutant ion source to the reaction tank, adds an insolubilizing agent, and operates the sludge return means to operate the water treatment device. It is an object of the present invention to provide a method for starting up a water treatment apparatus in a short period of time by circulating water of water and accumulating a predetermined amount of insoluble matter in a solid-liquid separation tank.

The water treatment apparatus start-up method according to claim 1 of the present invention separates a reaction liquid containing insoluble matter produced by a reaction between the inorganic contaminant ions and an insolubilizing agent from sludge containing the insoluble matter. In a method for starting up a water treatment apparatus, comprising: a solid-liquid separation tank for solid-liquid separation into liquid; and sludge return means for returning sludge containing the insoluble matter separated into solid and liquid to the reaction tank. Prior to supplying to the reaction tank, the water treatment apparatus is first filled with water, then the compound containing the inorganic pollutant ion source and the insolubilizing agent are added to the reaction tank, and the sludge return means is operated. The water in the water treatment apparatus is circulated, the addition of the compound is stopped when the insoluble matter in the solid-liquid separation tank reaches a predetermined amount, and the supply of raw water to the reaction tank is started. .

The water treatment apparatus startup method according to claim 2 of the present invention includes a reaction tank in which raw water containing inorganic contaminant ions is reacted with an insolubilizer that insolubilizes the inorganic contaminant ions; A solid-liquid separation tank for solid-liquid separation of a reaction liquid containing an insoluble matter produced by a reaction between a system contaminant ion and an insolubilizing agent into a sludge containing the insoluble matter and a separated liquid; Sludge returning means for returning sludge containing waste to a mixing tank to be described later, a mixing tank for mixing the returned sludge containing the insoluble matter and the insolubilizer, and reacting the mixture with the reaction In a method for starting up a water treatment apparatus having an addition means for adding to a tank, prior to supplying raw water to the reaction tank, the water treatment apparatus is first filled with water, and then an inorganic contaminant ion source is added to the reaction tank. A compound containing, While adding the solubilizer, the sludge return means is operated to circulate the water in the water treatment device, and when the insoluble matter in the solid-liquid separation tank reaches a predetermined amount, the addition of the compound is stopped, and the raw water Is started to be supplied to the reaction vessel.

According to the present invention, raw water containing inorganic pollutant ions is reacted with an insolubilizing agent that insolubilizes the inorganic pollutant ions to form insoluble matter, which is separated from sludge containing insoluble matter by solid-liquid separation. The water treatment apparatus for obtaining water can be started up in a short time. In addition, before the raw water starts to flow into the water treatment apparatus, it is set up in advance, and treated water with a predetermined water quality can be obtained simultaneously with the start of the raw water inflow.

Hereinafter, embodiments of a method for starting up a water treatment apparatus of the present invention will be described in detail with reference to the drawings.

1 and 2 are system diagrams showing an embodiment of a method for starting up a water treatment apparatus according to the present invention. In FIGS. 1 and 2, members having the same function are denoted by the same reference numerals.

In FIG. 1, reference numeral 1 denotes an introduction pipe for raw water (inorganic pollutant ion-containing wastewater), which introduces raw water into the reaction tank 2. 2A is a pH meter provided in the reaction tank 2, and 2B is a stirrer. 3 is a pipe for feeding the liquid in the reaction tank 2 to the coagulation tank 4 provided with the stirrer 4A, and 5 is a pipe for feeding the liquid in the coagulation tank 4 to the solid-liquid separation tank 6. 7 is a discharge pipe for treated water, and 8 is a discharge pipe for sludge separated in the solid-liquid separation tank 6, which branches into a discharge pipe 8A to the outside of the system and a return pipe 8B to the reaction tank 2. . 8C is a pump that returns a part of the separated sludge to the reaction tank 2. 9 is a pipe for supplying an insolubilizing agent to the reaction tank 2, and 10 is a pipe for supplying a polymer (polymer flocculant) to the coagulation tank 4.

In FIG. 1, in order to start up this water treatment apparatus, first, instead of introducing raw water (inorganic pollutant ion-containing wastewater) from the introduction pipe into the reaction tank, industrial water is injected into the reaction tank 2, and the reaction tank 2,
The aggregation tank 4 and the solid-liquid separation tank 6 are filled with water. Next, an inorganic contaminant ion source is added, an insolubilizing agent is supplied from the pipe 9, and the pump 8C is operated to circulate water. In the reaction tank 2, the inorganic contaminant ions react with the insolubilizing agent to generate insoluble matter, and the reaction solution flows into the aggregation tank 4. In the aggregation tank 4, the polymer is added from the pipe 10, and the generated insoluble matter is aggregated to facilitate solid-liquid separation. Next, the liquid containing the aggregated insoluble matter flows into the solid-liquid separation tank 6 and is separated into supernatant water and sludge containing the concentrated insoluble matter. The supernatant water is not discharged from the discharge pipe 7, and the sludge containing the concentrated insoluble matter is returned to the reaction tank 2 by the pump 8C. Without introducing raw water and without draining the supernatant water, supply of inorganic pollutant ion source and insolubilizer is continued, and at the stage where the specified sludge has accumulated in the solid-liquid separation tank, inorganic pollutant The supply of the solid ion source is stopped, the introduction of raw water into the reaction tank 2 is started, and the supernatant water in the solid-liquid separation tank 6 is discharged from the drain pipe 7 as treated water. In this manner, the start-up of the water treatment apparatus shown in FIG. 1 is completed, and the raw water is subsequently treated.

FIG. 1 shows an example in which the separated sludge in the solid-liquid separation tank is directly returned to the reaction tank 2, but as shown in FIG. 2, the separated sludge and the insolubilizer are mixed in advance in a mixing tank 11 equipped with a stirrer 11A. This is an example of feeding from the supply path 12 to the reaction tank 2 after that.

In FIG. 2, in order to start up this water treatment apparatus, first, instead of introducing raw water (inorganic pollutant ion-containing wastewater) from the introduction pipe into the reaction tank, industrial water is injected into the reaction tank 2, and the reaction tank 2,
The aggregation tank 4 and the solid-liquid separation tank 6 are filled with water. Next, an inorganic contaminant ion source is added, an insolubilizing agent is supplied from the pipe 9, and the pump 8C is operated to circulate water. In the reaction tank 2, the inorganic contaminant ions react with the insolubilizing agent to generate insoluble matter, and the reaction solution flows into the aggregation tank 4. In the agglomeration tank 4, the polymer is added from the pipe 10, and the generated insoluble matter is aggregated to facilitate solid-liquid separation. Next, the liquid containing the aggregated insoluble matter flows into the solid-liquid separation tank 6 and is separated into supernatant water and sludge containing the concentrated insoluble matter. The supernatant water is not discharged from the discharge pipe 7, but the sludge containing the concentrated insoluble matter is fed to the mixing tank 11 by the pump 8C. Without introducing raw water and without draining the supernatant water, supply of inorganic pollutant ion source and insolubilizer is continued, and at the stage where the specified sludge has accumulated in the solid-liquid separation tank, inorganic pollutant The supply of the solid ion source is stopped, the introduction of raw water into the reaction tank 2 is started, and the supernatant water in the solid-liquid separation tank 6 is discharged from the drain pipe 7 as treated water. In this manner, the start-up of the water treatment apparatus shown in FIG. 2 is completed, and the raw water is subsequently treated.

In FIG. 1 or FIG. 2, the agglomeration tank 4 is not necessarily required, but it is practical to provide the agglomeration tank 4 in the previous stage of the solid-liquid separation tank 6 to increase the insolubilized material.

In addition to metal ions that can be insolubilized only with alkali, inorganic contaminants contained in the raw water according to the present invention have a pH together with insolubilizers such as alkaline earth metal compounds such as fluorine, phosphoric acid, carbonic acid, and sulfurous acid. Some require alkali for adjustment, in this case,
A necessary amount of pH adjuster is added as appropriate.

The adjusted pH value in the reaction tank 2 varies depending on the type of inorganic contaminants in the raw water, the type of insolubilizer, and the like, but is generally in the range of 6 to 11. Specifically, the ions to be insolubilized are Al ³⁺
, Fe ³⁺ is preferably pH 6-7, and F ⁻ , PO ₄ ^3- is preferably pH 8
-10, Ni ²⁺ , Cd ²⁺ is preferably pH 10-11.

  Hereinafter, the present invention will be described more specifically with reference to examples.

Example 1
When the raw water containing fluoride ions was treated with the apparatus shown in FIG. 2, the apparatus was started up using hydrofluoric acid as the inorganic contamination source ion source and calcium hydroxide as the insolubilizing agent.
[Reaction tank 2]
Tank capacity: 12m ³
[Coagulation tank 4]
Tank capacity: 6m ³
[Solid-liquid separation tank (precipitation tank) 6]
Separation area: 9m ²
Effective capacity: 36m ³
[Mixing tank 11]
Tank capacity: 0.25m ³
After filling the reaction tank 2, the coagulation tank 4 and the solid-liquid separation tank 6 with water, 86 g / min of hydrofluoric acid is supplied to the reaction tank 2 in a pure amount, and calcium hydroxide is supplied to the mixing tank 11 in a pure amount. When the pump 8C was operated and the sludge return flow rate was gradually increased to 0.10 to 0.25 m ³ / min and operated continuously for 36 hours, the solid-liquid separation tank 6 Sludge containing calcium fluoride at a high concentration was accumulated, and the return sludge concentration became 50 to 120 g / L.

After that, the supply of sodium fluoride as an inorganic pollution source ion source was stopped, the supply of raw water of the following quality was started, and the treated water was discharged from the drain pipe 7. The quality of the treated water was as follows. It was.

Raw water quantity: 0.4-0.6 m ³ / min Raw water quality: F ^- 20-150 mg / L
PO ₄ ^3- 30~50mg / L,
SS 50-100mg / L
Treated water quality: F ^- 6-15mg / L
PO ₄ ³ 3-5 mg / L
SS 0-10mg / L
Example 2
In treating the waste water containing trivalent iron ions and arsenic with the apparatus shown in FIG. 1, the apparatus was started up using ferric chloride as the inorganic contamination source ion source and sodium hydroxide as the insolubilizing agent.
[Reaction tank 2]
Tank capacity: 8m ³
[Coagulation tank 4]
Tank capacity: 4m ³
[Solid-liquid separation tank (precipitation tank) 6]
Separation area: 20m ²
Effective capacity: 60m ³
After filling the reaction tank 2, the coagulation tank 4 and the solid-liquid separation tank 6 with industrial water, 820 g / min of pure ferric chloride is supplied to the raw water introduction pipe 1, and sodium hydroxide is purely supplied to the mixing tank 11. 125g /
In addition, the pump 8C is operated and the sludge return flow rate is 0.05 to 0.15 m ³ /
When the operation was continued for 48 hours with the temperature gradually raised to 50 minutes, sludge containing a high concentration of insolubilized iron was accumulated in the solid-liquid separation tank 6 and the return sludge concentration became 50 to 80 g / L.

After that, the supply of ferric chloride as an inorganic source ion source was stopped, the raw water of the following quality was started, and the treated water was discharged from the drain pipe 7. The quality of the treated water was as follows: there were.
Raw water quantity: 0.25-0.30 m ³ / min Raw water quality: Fe ³⁺ 5-10 mg / L
As 16-70 mg / L,
SS 50-350mg / L
Treated water quality: Fe ³⁺ 0-0.1 mg / L
As 0-0.01 mg / L,
SS 0-1mg / L

It is a systematic diagram which shows embodiment of the starting method of the water treatment apparatus of this invention. It is a systematic diagram which shows other embodiment of the starting method of the water treatment apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Raw water introduction pipe 2 Reaction tank 3 Piping 4 Coagulation tank 5 Piping 6 Solid-liquid separation tank 7 Discharge pipe 8 Sludge extraction pipe 8A Discharge pipe 8B Return pipe 8C Pump 9 Insolubilizer supply pipe 10 Polymer supply pipe 11 Mixing tank

Claims (2)

A reaction vessel for reacting raw water containing inorganic contaminant ions with an insolubilizer that insolubilizes the inorganic contaminant ions;
A solid-liquid separation tank for solid-liquid separation of a reaction liquid containing an insoluble matter produced by a reaction between the inorganic contaminant ions and an insolubilizing agent into a sludge containing the insoluble matter and a separation liquid;
Sludge returning means for returning the sludge containing the insoluble matter separated into solid and liquid to the reaction tank;
In the start-up method of the water treatment device having
Prior to supplying raw water to the reaction tank, the water treatment apparatus is first filled with water, and then a compound containing an inorganic pollutant ion source and the insolubilizing agent are added to the reaction tank, and the sludge return means is operated. The water in the water treatment apparatus is circulated, and the addition of the compound is stopped when the insoluble matter in the solid-liquid separation tank reaches a predetermined amount, and the supply of raw water to the reaction tank is started. A method for starting up a water treatment device. A reaction vessel for reacting raw water containing inorganic contaminant ions with an insolubilizer that insolubilizes the inorganic contaminant ions;
A solid-liquid separation tank for solid-liquid separation of a reaction liquid containing an insoluble matter produced by a reaction between the inorganic contaminant ions and an insolubilizing agent into a sludge containing the insoluble matter and a separation liquid;
Sludge returning means for returning the sludge containing the insoluble matter separated into solid and liquid to a mixing tank described later;
A mixing tank in which the returned sludge containing the insoluble matter and the insolubilizing agent are mixed to form a mixture;
In a method for starting up a water treatment apparatus having an addition means for adding the mixture to the reaction vessel,
Prior to supplying raw water to the reaction tank, first, water treatment equipment is filled with water, then a compound containing an inorganic contaminant ion source is added to the reaction tank, the insolubilizing agent is added to the mixing tank, Operate the sludge return means to circulate the water in the water treatment device, stop the addition of the compound when the insoluble matter in the solid-liquid separation tank reaches a predetermined amount, and supply raw water to the reaction tank The start-up method of the water treatment apparatus characterized by starting.

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