JP2018197471A - Recharge method - Google Patents

Abstract

To make it possible to preferably supply a precoat material and accurately form a precoat layer on a surface of a spring-type filter.SOLUTION: A recharge method including removing an insoluble substance in object water W1 by filtering the object water W1 using a spring-type filter 11 having a surface on which precoat material is deposited and a precoat layer is formed and pouring object water W2 after processing of removing the insoluble substance has been performed, from a water pouring well 4 into the underground includes a precoat layer formation step of forming a precoat layer on the surface of the spring-type filter 11 by previously mixing the precoat material with water to obtain slurry-like precoat liquid S, supplying the precoat liquid S to a precoat tank 13 using a pump 18, and filtering the precoat liquid S using the spring-type filter 11.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a recharge method used in excavation work or the like.

  In general, in underground excavation work, in order to moderate moisture in the excavation part, excavation is often performed in a state where the groundwater in the excavation part is pumped up near the ground surface in advance and the groundwater level is lowered before excavation. At this time, in order to reduce the discharge amount of groundwater and to reduce the influence due to the lowering of the water level around the site, a recharge method for returning the groundwater pumped back to the ground is often used.

  On the other hand, in the conventional recharge method, clogging of the ground near the screen of the water injection well (recharge well) is likely to occur, and it is difficult to maintain the water flow performance / water injection performance of the water injection well for a long period of time. For this reason, various techniques for removing clogging substances contained in the groundwater pumped to the ground surface have been proposed and put into practical use.

  For example, Patent Document 1 discloses a clogging prevention device (recharge system) including a cylindrical hollow tube and a cylindrical filter provided at the center of the hollow tube. .

  In this clogging prevention device, an annular space is formed between the inner periphery of the hollow tube body and the outer periphery of the filter unit, and effluent water containing construction-generated water, rainwater, groundwater, etc. is tangentially connected to the annular space. It introduce | transduces so that the swirl | flow may arise so that it may face downward with respect to a horizontal line from a direction. At this time, the foreign matter having a large weight falls in the discharged water due to the centrifugal force and the difference in gravity, and the foreign matter having a small weight floats upward. The foreign matter can be filtered and removed by the filter unit.

  However, since the clogging prevention device is mainly intended to remove suspended solids (SS) components such as clay particles, even if this clogging prevention device is used, clogging of the recharge method is not possible. It is difficult to sufficiently suppress the occurrence of the phenomenon.

  In addition, in order to restore the water flow performance of the water injection well, even if the recharge is stopped and the water injection well is backwashed over time, the water flow performance will be reduced if the ground near the water injection well is clogged. It is difficult to restore to the initial state.

  On the other hand, the inventors / applicants of the present application have made extensive studies, and the clogging of the ground near the water injection well is caused by a large amount of iron components contained in groundwater (discharged water) in addition to SS components such as soil particles. For example, a method for treating groundwater to prevent trivalent iron from reaching the vicinity of the water injection part (screen) of the water injection well has been invented, and a patent application has already been filed (Japanese Patent Application No. 2006). 075417).

  In addition, the inventors / applicants of the present application attach a precoat material made of, for example, diatomaceous earth as a raw material to the surface of the spring-type filter, and filter groundwater with the spring-type filter and the precoat material. It has been found that filtration can be realized at high speed and low pressure, and trivalent iron and the like can be suitably removed.

  Further, when the precoat material 12 is adhered to the surface of the spring filter 11, as shown in FIG. 2, the powder precoat material 12 is placed in a precoat tank 13 below a predetermined amount of water and an auxiliary agent supply tank (hopper) ) A fixed amount is dropped from the charging port at 14, and the mixture is stirred. Then, the precoat liquid S in which the precoat material 12 is uniformly dispersed / mixed is filtered from the precoat tank 13 by the spring type filter 11 of the filtration device 16 to form the precoat layer 17 on the surface of the spring type filter 11.

Japanese Patent No. 4379086

  However, since a powdered precoat material is used, if the precoat material contains humidity, the adhesiveness increases, causing inconveniences such as not falling due to gravity from the inlet of the auxiliary agent supply tank. There were problems such as being unable to supply the tank. For this reason, there are significant restrictions and troubles in controlling the humidity of the powder when storing and charging the precoat material outdoors and the weather at the time of charging, and it has been strongly desired to improve this point.

  In view of the above circumstances, an object of the present invention is to provide a recharge method that enables a precoat material to be suitably supplied and a precoat layer to be accurately formed on the surface of a spring-type filter.

  In order to achieve the above object, the present invention provides the following means.

  In the recharge method of the present invention, the target water is filtered using a spring-type filter in which a precoat material is attached to the surface to form a precoat layer to remove insoluble substances in the target water, and the insoluble substances are removed. This is a recharge method in which the target water is injected into the ground from the water injection well. In the precoat layer formation process, the precoat material is mixed with water in advance to form a slurry precoat liquid, and the precoat liquid is supplied to the precoat tank by a pump. The precoat layer is formed on the surface of the spring filter by filtering the precoat liquid with the spring filter.

  In the recharge method of the present invention, compared with the case where the powder precoat material is supplied to the precoat tank, it is in the form of a slurry, so that the necessary precoat material can be introduced easily and accurately, and the spring-type filter is uniformly and preferably used. A precoat layer can be formed on the surface.

  Thereby, it is not necessary to limit the installation position of the auxiliary agent supply tank near the filtration device, and it is possible to install the auxiliary coating tank at an arbitrary place where the precoat material is easily carried.

  Further, if a metering pump such as a MONO pump is used as a means for transporting the precoat material in a high-density slurry state, the supply amount of the precoat material to the precoat tank can be managed in the pump operation time.

  Further, by using the pre-coating material previously formed into a high-density slurry in this way, it becomes unnecessary to consider humidity management, weather at the time of charging, etc., and construction management can be facilitated.

  Therefore, according to the recharge method of the present invention, it is possible to supply the precoat material more suitably and to form the precoat layer on the surface of the spring type filter with high accuracy as compared with the conventional case. In addition, management of the precoat material and the like can be facilitated, and it is possible to improve workability and economy.

It is a figure which shows the recharge construction method which concerns on one Embodiment of this invention. It is a figure which shows the method of forming a precoat layer on the surface of the conventional spring type filter.

  Hereinafter, a recharge method according to an embodiment of the present invention will be described with reference to FIG.

First, for example, this embodiment is installed at a site where excavation work or the like is performed, and the groundwater is pumped from the ground aquifer by a pumping well to control the groundwater level, and the pumped-up groundwater is brought to a desired position. The present invention relates to a recharge method that leads to an installed water injection well (recharge well) and returns water from the water injection well to the ground and a system of the recharge method.
In addition, if the recharge construction method is applicable, the present invention does not need to specifically limit the structure of the ground, the pumping position, and the water injection position.

  Further, in the recharge system and the recharge method according to the present embodiment, for example, an oxidant is added to the pumped ground water, and the divalent iron dissolved in the ground water of the target water in the present invention is oxidized to form insoluble / slightly soluble three. It is configured to return to underground after removing trivalent iron (insoluble material) by filtering it from groundwater.

  Specifically, as shown in FIG. 1, the recharge system A of the present embodiment includes a pumping well (not shown) for pumping up the groundwater that is the target water of the present embodiment, and the groundwater W1 pumped from the pumped well. The oxidant addition means 1 for adding the oxidant P, the raw water tank 2 for temporarily storing the groundwater W1 after the addition of the oxidant P, and the groundwater W1 from the raw water tank 2 are introduced into the groundwater W1. It comprises a removal processing means 3 for removing SS components and the like, and a water injection well 4 for injecting and returning the groundwater W2 treated by the removal processing means 3 to the underground aquifer.

  The pumping well is a facility for pumping groundwater from the underground aquifer to the ground, and includes, for example, a deep well provided in an excavation area partitioned by earth retaining. In addition, the pumping well is provided with a screen (collecting part) disposed in an aquifer deeper than the groundwater level, and is configured to allow groundwater to flow into the inside through this screen.

  Here, in the groundwater W1 pumped from the pumping well, iron is generally dissolved as divalent iron. When the divalent iron dissolved in the groundwater W1 comes into contact with air (oxygen), insoluble / slightly soluble trivalent iron. To change. For this reason, in the recharge system A of this embodiment, it connects between a pumping well and the oxidizing agent addition means 1 with a pumping pipe, prevents that the groundwater W1 pumped up from the pumping well to the ground is exposed to air, and groundwater W1 It is configured so that the divalent iron inside does not change to trivalent iron.

  The oxidant addition means 1 is for adding the oxidant P to the groundwater W1 sent through the pumping pipe, mainly for oxidizing the divalent iron dissolved in the groundwater W1 to the trivalent iron, and the groundwater W1. And an agitation device (mixing device) 5 for agitating the ground water W1 to which the oxidant P is added. The configuration of the oxidant adding means 1 is not particularly limited as long as the oxidant P can be supplied to the groundwater W1.

  The oxidant P supplied by the oxidant addition means 1 is not particularly limited as long as it can oxidize divalent iron generally contained in the groundwater W1 and precipitate trivalent iron. Examples of the oxidizing agent P include sodium hypochlorite, hydrogen peroxide, sodium chlorate, ozone, chlorine and the like.

  Further, since it has been confirmed by the inventors of the present application that manganese, like iron, is clogged, the oxidizing agent P oxidizes not only divalent iron but also manganese dissolved in the groundwater W1 and hydrates it. It is preferable to include a substance that can be deposited as manganese dioxide or the like.

  The stirring device (mixing device) 5 is a static mixer or the like, and is configured so that the groundwater W1 to which the oxidizing agent P is added flows and the groundwater W1 and the oxidizing agent P can be mixed. In addition, if the groundwater W1 and the oxidizing agent P can be mixed in a desired state, the configuration (mixing method) is not particularly limited.

  The removal treatment means 3 is composed of SS components (insoluble substances) in the groundwater W1 sent from the raw water tank 2, and insoluble / slightly soluble metal oxides (insoluble substances) including iron and manganese oxidized by the oxidizing agent P. This is a facility for removing water, and includes a filtration device 16 having a spring filter.

  The spring type filter is made of, for example, stainless steel (SUS) made of a very rust-resistant material into a special wire shape, and a precoat material 12 is applied to the surface of the spring type filter 11 in which a hard spring wire is wound in a coil shape. The groundwater W1 is filtered by using the deposited layer (precoat layer 17) of the precoat material 12 as a filter.

  Moreover, the precoat material 12 adhering to the surface of the spring type filter 11 can be peeled off and removed only by expanding / contracting / elastically deforming the spring type filter 11. That is, the removal residue is separated together with the precoat material 12 by peeling off the precoat material 12 at the stage where the removal residue such as the SS component in the groundwater W1 and the metal oxide such as trivalent iron is filtered and captured. It is configured so that it can be collected.

  Such a spring type filter can include, for example, a liquid type filter element disclosed in Japanese Patent Laid-Open No. 8-196211, a spring type filter filter device disclosed in Japanese Patent No. 1822317, etc. It has a particularly excellent self-cleaning effect and backwashing regeneration function.

  The spring-type filter 11 has been conventionally used mainly for wastewater (turbid water) treatment. In the filtration treatment, the pre-coat material 12 and the filter aid that are coated on the spring-type filter 11 in the first stage are used. By appropriately selecting 15, the particle size (filtration accuracy) filtered by the spring filter 11 can be determined, and precise filtration can be realized at high speed and low pressure. By utilizing such a self-cleaning effect and filtering water containing trivalent iron with the spring filter 11, trivalent iron and the like can be suitably removed. That is, an additive such as a flocculant is unnecessary for the spring type filter.

  The water injection well 4 is a recharge well, that is, a known water injection facility for injecting groundwater into the aquifer. The water injection well 4 includes a screen (water injection part) 4a embedded in the ground (aquifer) deeper than the groundwater level, and is configured so that the ground water W2 in the water injection well 4 can be injected into the aquifer from the screen 4a. Has been. Moreover, a lid is attached to the upper end of the water injection well 4, and the water injection well 4 is sealed.

  And in the recharge system A of this embodiment which consists of the said structure, the oxidizing agent P is added by the oxidizing agent addition means 1 to the groundwater W1 pumped from the pumping well, and divalent iron (and manganese) in the groundwater W1 is added. Oxidizes and precipitates as trivalent iron.

  Precipitated metal oxides such as trivalent iron and manganese, and insoluble substances such as SS components such as clay particles are filtered by the removal treatment means 3 and removed from the groundwater W1. Thereby, the clogging cause component contained in the groundwater W1 can be removed by the removal processing means 3.

  According to the recharge system A and the recharge method of the present embodiment, the groundwater W1 pumped from the pumping well is removed to remove the components that cause clogging of the ground G in the vicinity of the water injection well 4 to be in a good state. The groundwater W1 pumped up can be returned to the ground G while preventing clogging of the ground G and the screen 4a of the water injection well 4 and maintaining good water flow performance.

  On the other hand, in the recharge method using the recharge system A of the present embodiment, the powder precoat material 12 is charged into the precoat tank 13 in the precoat layer forming step of forming the precoat layer 17 on the surface of the spring filter 11. Rather than stirring and mixing, the precoat material 12 is stored in the auxiliary agent supply tank 20 in the state of a concentrated solution, and a predetermined amount required for one precoating operation of the spring filter 11 is supplied to the precoat tank 13 each time. To do.

  Moreover, in this embodiment, the precoat material 12 manufactured using, for example, diatomaceous earth as a raw material, such as 600H manufactured by Chuo Silica Co., Ltd., is made into a solution at a concentration that does not become plastic, for example, a concentration of 25 wt% or less, and the precoat material 12 is In order to store it as densely as possible, it is stored in the auxiliary agent supply tank 20 at a concentration of about 25 wt%.

  Thereby, in the recharge method of this embodiment, compared with the case where the powder precoat material 12 is supplied to the precoat tank 13, since it is in the form of a slurry, the necessary precoat material 12 can be introduced easily and accurately. Thus, the precoat layer 17 can be preferably formed on the surface of the spring filter 11.

  Moreover, it becomes unnecessary to limit the installation position of the auxiliary agent supply tank 20 to the vicinity of the filtration device 16, and it is possible to install the auxiliary coating tank 20 in an arbitrary place where the precoat material 12 is easily carried. In addition, what is necessary is just to select the kind and capacity | capacitance of the pump pumped in consideration of the pressure loss by a hose.

  Furthermore, if a metering pump 18 such as a MONO pump is used as means for transporting the precoat material 12 in a high-density slurry state, the supply amount of the precoat material 12 to the precoat tank 13 can be managed in the pump operation time.

  Furthermore, by using the precoat material 12 previously made into a high-density slurry, it becomes unnecessary to consider humidity management, weather at the time of charging, and the like, and construction management can be facilitated.

Further, the density of the pre-coat material 12 in the case of storing in the solution was 0.28 g / cm ³ at a concentration of 25 wt%, is substantially equal to the bulk density 0.25 g / cm ³ at the time of the powder. Thereby, there is almost no difference in the required amount of the tank 20 compared with the case where it is stored in a silo, and the handling of storage is not deteriorated by making the slurry.

  Therefore, according to the recharge method of the present embodiment, it is possible to supply the precoat material 12 more suitably and to form the precoat layer 17 on the surface of the spring type filter 11 with higher accuracy than in the conventional case. Become. Moreover, management of the precoat material 12 etc. can be made easy and it becomes possible to aim at improvement of workability and economical efficiency.

  As mentioned above, although one embodiment of the recharge method according to the present invention has been described, the present invention is not limited to the above embodiment, and can be appropriately changed without departing from the scope of the present invention.

  In the present embodiment, a pumping well is installed at a site where excavation work or the like is performed, and the groundwater W1 pumped from the pumping well is treated and returned to the ground aquifer from the water injection well 4. The invention may be applied, for example, when pumping contaminated groundwater to the ground and purifying it, returning it to the ground, or treating water such as drainage on the ground and pouring water into the ground. There is no need to limit.

  Furthermore, the oxidant P exceeding the necessary amount is added, and the remaining amount of the oxidant P in the groundwater W2 treated by the removal processing means 3 (that is, the amount of oxidant detected as the redox potential of the groundwater) is predetermined. You may comprise the reducing agent addition means which adds a reducing agent until it becomes below a value, and injects the groundwater W2 after adding a reducing agent from the water injection well 4 to an aquifer.

1 Oxidizer addition means 2 Raw water tank 3 Removal treatment means 4 Water injection well 4a Screen 5 Stirring device (mixing device)
11 Spring type filter 12 Precoat material 13 Precoat tank 14 Auxiliary agent supply tank (hopper)
16 Filtration device 17 Precoat layer 20 Auxiliary supply tank A Recharge system G Ground P Oxidant S Precoat liquid W1 Groundwater (target water)
Groundwater after W2 treatment

Claims (1)

Filter the target water using a spring-type filter with a precoat layer attached to the surface to form a precoat layer, and remove insoluble substances in the target water.
A recharge method for pouring the target water after removing the insoluble material from a water injection well into the ground,
In the precoat layer forming step, the precoat material is mixed with water in advance to form a slurry-like precoat liquid, and the precoat liquid is supplied to the precoat tank by a pump, and the precoat liquid is filtered by the spring-type filter. A recharge method characterized in that the precoat layer is formed on the surface of a filter.

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