JP2018197469A - Recharge system and recharge method - Google Patents

Abstract

To provide a recharge system and a recharge method that are capable of eliminating sewage water discharge of effluent such as underground water at the time of maintenance, and makes it possible to implement efficient and inexpensive preferable operation.SOLUTION: A recharge system comprises: oxidant addition means 1 for adding an oxidant P to object water W1 at ground level; a raw water tank 2 for temporarily retaining the object water W1 including the oxidant P added by the oxidant addition means 1; removal processing means 3 for filtering the object water W1 sent from the raw water tank 2, using a filtering device 11; and a water pouring well 4 for pouring object water W2 after processing of the removal processing means 3 into the underground. The capacity of the raw water tank 3 is set depending on a washing frequency and/or washing time for performing backwashing on the filtering device 11.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a recharge system and a recharge method used in excavation work and 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 can achieve precise filtration at high speed and low pressure by attaching a precoat material to the surface of the spring filter and filtering groundwater with the spring filter and the precoat material. In addition, it has been found that trivalent iron and the like can be suitably removed.

Japanese Patent No. 4379086

  Here, in the recharge method, clogged substances in the groundwater pumped up are removed on the ground using a filter / filtration device or the like. For this reason, the filter / filtration device inevitably becomes clogged with the increase in the amount of treated water, and the filtration performance thereof is lowered, and regular maintenance such as backwashing is required.

  Conventionally, when the filter / filter device is maintained by backwashing or the like, it cannot be recharged, so the groundwater pumped during this time has to be discharged into the sewer. This necessitates complicated operations and operations such as sewage discharge / recharge valve switching in accordance with the frequency of maintenance such as backwashing, and a large cost burden such as sewage usage fees accompanying sewage discharge.

  Here, for example, FIG. 6 exemplifies a case of cleaning with a frequency of about once every hour using a spring type filter. From this figure, it can be seen that the influence of the cleaning time on the entire processing is very large. As described above, in the conventional method, the recharge is frequently stopped with the maintenance, and there is a problem that the cost increases in accordance with the discharge of the pumped-up groundwater.

  In view of the above circumstances, the present invention provides a recharge system and a recharge method that can eliminate the need to discharge drain water such as groundwater during maintenance, and enable efficient, economical, and suitable operation. The purpose is to do.

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

  The recharge system of the present invention includes an oxidant adding means for adding an oxidant to the target water on the ground, a raw water tank for temporarily storing the target water to which the oxidant is added by the oxidant adding means, and the raw water tank. A removal treatment means for removing the insoluble substances in the target water by filtering the target water sent from the filtration device, and a water injection well for pouring the target water treated by the removal treatment means into the ground The raw water tank has a capacity for storing target water in accordance with a cleaning frequency and / or a cleaning time for backwashing the filtration device.

  In the recharge system of the present invention, the raw water tank has a storage part having a capacity for temporarily storing the target water, a supply port for receiving the target water sent from the agent adding means, and A discharge port for sending the target water supplied and circulated from the supply port to the storage unit, and a flow until the target water supplied from the supply port is discharged from the discharge port to the storage unit; It is desirable to provide a reaction section configured such that the path length / volume is the required flow path length / volume.

  Furthermore, in the recharge system of the present invention, the target water flow control for controlling the flow direction and / or flow velocity and / or flow rate of the target water flowing through the flow path from the supply port to the discharge port of the reaction unit. More preferably, means are provided.

  The recharge method of the present invention adds an oxidizing agent to the target water on the ground, temporarily stores the target water to which the oxidizing agent is added in the raw water tank, and filters the target water sent from the raw water tank with a filtration device. And removing the insoluble substances in the target water, and recharging the target water after removing the insoluble substances from the water injection well into the ground. The raw water tank is washed to backwash the filtration device. The capacity for storing the target water is set according to the frequency and / or the washing time, and when the filtration device is backwashed by stopping the recharge for pouring the target water into the ground from the water injection well, the oxidation is performed. The target water to which the agent is added is continuously sent to the raw water tank.

  According to the recharge system and the recharge method of the present invention, it is not necessary to discharge drain water such as groundwater during maintenance, and it is possible to realize an efficient, economical and suitable operation.

It is a figure which shows the recharge system which concerns on one Embodiment of this invention. It is a figure which shows the raw | natural water tank which concerns on one Embodiment of this invention. It is a figure which shows the cycle time of the recharge construction method which concerns on one Embodiment of this invention. It is a flowchart which shows the method of determining cycle time and process flow volume. It is a figure which shows the relationship of the total surface area of a spring filter-the filtration time of 1 cycle-the number / length of a spring type filter-iron concentration of object water. It is a figure which shows the conventional driving | running condition.

  Hereinafter, a recharging system and a recharging method according to an embodiment of the present invention will be described with reference to FIGS. 1 to 6.

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 FIGS. 1 and 2, the recharge system A of the present embodiment is pumped from a pumping well (not shown) for pumping up the ground water that is the target water of the present embodiment, and the pumped well. The oxidant addition means 1 for adding the oxidant P to the groundwater W1, 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. The removal treatment means 3 for removing the SS component and the like present in the water and the water injection well 4 for injecting and returning the groundwater W2 treated by the removal treatment means 3 to the underground aquifer are returned. ing.

  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.

  Next, the raw water tank 3 is for temporarily storing the groundwater W1 to which the oxidant P is added by the oxidizer addition means 1, and from the pumping well during maintenance of the filter / filtration device of the removal treatment means 3 A storage unit 6 having a capacity capable of temporarily receiving and storing the pumped-up groundwater W1 is provided.

  Furthermore, the raw water tank 3 of the present embodiment has a supply port 7a that receives the groundwater W1 sent from the oxidant addition means 1 and a drain for sending the groundwater W1 that is supplied and distributed from the supply port 7a to the storage unit 6. Reaction which has outlet 7b and was formed so that channel length / volume until groundwater W1 supplied from supply port 7a was discharged from discharge port 7b to storage part 6 became more than required channel length / volume Part 7 is provided. In this embodiment, the reaction part 7 is formed by providing the some partition plate 8 which divides the inside of the raw | natural water tank 2, and arrange | positioning these some partition plates 8 in a predetermined position.

  Further, the raw water tank 2 includes processing target water flow control means 10 for controlling the flow direction and flow velocity (flow rate per hour) of the groundwater W1 flowing through the flow path R of the reaction unit 7. In this embodiment, this process target water flow control means 10 is provided with a stirrer such as a stirring screw that rotates around an axis.

  Then, the ground water W1 mixed with the oxidant P by the stirring device 5 is supplied from the supply port 7a of the reaction unit 7 of the raw water tank 2, and the flow path R of the reaction unit 7 is sequentially supplied by driving the processing target water flow control means 10. It distribute | circulates from the opening 7a to the discharge port 7b. At this time, since the flow path R of the reaction section 7 is formed with a predetermined required flow path length / volume, the oxidant P in the flow path R and divalent iron, manganese, etc. dissolved in the groundwater W1. A sufficient reaction time is secured.

  That is, the raw water tank 2 of the present embodiment is configured such that almost the entire amount of divalent iron or manganese in the groundwater W1 is deposited as trivalent iron or hydrated manganese dioxide in the reaction section 7.

  The removal processing means 3 is an insoluble / slightly soluble metal oxide including SS components (insoluble substances) in the groundwater W1 sent from the storage unit 6 of the raw water tank 2, iron and manganese oxidized by the oxidizing agent P. It is equipment for removing (insoluble substances), and includes a filtration device 11 having a spring filter.

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

  Moreover, the precoat material adhering to the surface of the spring type filter can be peeled off and removed simply by expanding / contracting / elastically deforming the spring type filter. That is, by removing the pre-coating material at the stage where the removal residue such as SS components in groundwater and metal oxides such as trivalent iron is filtered and captured, the pre-coating material can be separated and recovered together with the pre-coating material. It is configured.

  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 above spring-type filter has been used mainly for wastewater (turbid water) treatment. However, pre-coat material (filter aid) that coats the spring-type filter at the first stage is suitable for filtration treatment. By selecting this, it is possible to determine the particle size (filtration accuracy) filtered by the spring type filter, and it is possible to realize precise filtration at high speed and low pressure. By utilizing such a self-cleaning effect and filtering water containing trivalent iron with a spring-type filter, 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.

  The deposited metal oxide such as trivalent iron and manganese is filtered by the removal processing means 3 together with the SS component such as clay particles and removed from the ground water 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 system A of this embodiment, the raw water tank 2 is provided with a reaction section 7 by two or a plurality of partition plates 8 like a notch tank, and added to the ground water W1 before being charged into the raw water tank 2. A residence time during which the oxidizing agent P sufficiently reacts can be ensured.

  That is, the flow path R of the groundwater R1 supplied into the raw water tank 2 by the reaction unit 7 is defined, and further, the required flow path length / volume of the flow path R until the reaction unit 7 is discharged to the storage unit 6 is provided. Since it is formed, it can sufficiently react with the oxidizing agent P in the flow path R of the reaction section 7 to oxidize the divalent iron to form insoluble / slightly soluble trivalent iron.

  Furthermore, at this time, the raw water tank 2 of the present embodiment distributes water to be treated such as a stirrer for controlling the flow direction and flow speed (flow rate per hour) of the groundwater W1 flowing in the flow path R of the reaction unit 7. Control means 10 is provided. For this reason, by drive control of this process target water flow control means 10, it can react with oxidizing agent P in channel R of reaction part 7 more reliably, and can change divalent iron into trivalent iron. In addition, the oxidant P can be suitably mixed and stirred with the groundwater W1 by the drive control of the processing target water flow control means 10.

  In the recharging system A and the recharging method of the present embodiment, divalent iron or manganese is changed into insoluble trivalent iron or hydrated manganese dioxide from the outlet 7b of the reaction section 7 formed by the partition plate 8. The groundwater W1 in a state can be supplied to the storage unit 6.

  Thus, the groundwater W1 sent from the storage unit 6 of the raw water tank 2 is filtered by the spring-type filter of the filtration device of the removal processing means 3, so that trivalent iron such as trivalent iron or hydrated manganese dioxide is mixed with the SS component. The metal can be removed.

  That is, in the recharge system A and the recharge method according to the present embodiment, when the groundwater W2 is returned from the water injection well 4 to the ground aquifer and injected, the screen 4a of the water injection well 4 and the water injection are compared. It is possible to prevent clogging from occurring in the gap between the ground G near the well 4.

  Therefore, according to the recharge system A and the recharge method of the present embodiment, the water passage performance of the water injection well 4 can be suitably maintained over a long period of time, and the performance / efficiency of the recharge system A and the recharge method can be greatly improved. Is possible.

  Here, as described above, the SS component, iron, and the like in the groundwater W1 are effectively removed by the filtration device of the removal processing means 3. For this reason, it is necessary to perform maintenance such as backwashing the filtration device.

  At this time, in this embodiment, the raw water tank 2 is provided, and the storage section 6 of the raw water tank 2 is formed with a capacity sufficient to store the groundwater stored during the cleaning time. In other words, the shape and capacity of the raw water tank 2 of this embodiment are set according to the cleaning frequency and the cleaning time.

  Thereby, in the recharge system A and the recharge method of this embodiment, it is not necessary to stop the pumping of the groundwater W1 from the pumping well during the maintenance of the filtration device as in the prior art, and the pumped-up groundwater W1 is discharged to the sewer. Can be made unnecessary.

  More specifically, when the filtration time is t and the backwash time is Δt, the cycle in which recharge is performed by the recharge system A and the recharge method according to the present embodiment can be expressed as shown in FIG. Assuming that the processing flow rate for flowing at the average processing flow rate Q as a whole system taking t into account is Q ′, Q ′ is expressed by the following equation (1). Incidentally, the backwash time Δt is about 15 minutes.

  Based on this, in the recharge system A and the recharge method according to the present embodiment, as shown in FIG. 4, the average treatment flow rate (planned treatment flow rate) Q is determined, and the water quality such as the iron concentration of the groundwater (target water) W1 to be pumped is determined. The total surface area of the spring filter as shown in FIG. 5 that has been confirmed and filtered, such as the number of spring filters, with reference to the relationship between the filtration time of one cycle—the number / length of spring-type filters—the iron concentration of the target water Define equipment specifications. Then, the backwash time and the backwash cycle time are determined and the processing flow rate Q ′ is obtained, and the convergence state of this Q ′ is confirmed.

  If the convergence of Q ′ is made as small as possible, the optimum cycle time t + Δt and processing flow rate Q ′ that can realize efficient and effective processing can be set / determined.

  Furthermore, in order to realize processing with an efficient, effective and optimal cycle time t + Δt and processing flow rate Q ′, the specifications of the raw water tank may be set / determined as follows.

When the volume of the storage unit 6 of the raw water tank 3 is V _A , the required volume of the reaction unit is V _B , and the time from the introduction of the oxidant to the completion of the desired reaction is t _act , the following equation (2 ), The raw water tank 3 of the present embodiment is configured to satisfy the formula (3).

  If the raw water tank 3 is configured in this way, it is possible to reliably change divalent iron to trivalent iron, fully exhibit the performance of the filter / filtration device, and realize efficient, effective and optimal treatment. .

  Therefore, according to the recharge system A and the recharge method of the present embodiment, complicated work and operation such as sewage discharge / recharge valve switching according to the frequency of maintenance such as backwashing can be made unnecessary, and accompanying sewage discharge. It becomes possible to eliminate a large cost burden such as a sewerage usage fee.

  As mentioned above, although one Embodiment of the recharge system and the recharge construction method concerning this invention was described, this invention is not limited to said embodiment, It can change suitably in the range which does not deviate from the meaning.

  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.

  Moreover, in this embodiment, although the reaction part 7 of the raw | natural water tank 3 and the flow path R of the groundwater W were formed with the two partition plates 8, it is not necessary to limit the number of the partition plates 8. Furthermore, the flow path R need not be formed by the partition plate 8. Moreover, the movable partition plate 8 may be provided, and the capacity | capacitance of the storage part 6 and the flow path length / volume of the reaction part 7 may be comprised so that adjustment is possible.

1 Oxidizer addition means 2 Raw water tank 3 Removal treatment means 4 Water injection well 4a Screen 5 Stirring device (mixing device)
6 Storage part 7 Reaction part 7a Supply port 7b Discharge port 8 Partition plate 10 Processed water flow control means 11 Filtration device A Recharge system G Ground P Oxidant W1 Ground water (target water)
Groundwater after W2 treatment

Claims (4)

An oxidizer addition means for adding an oxidizer to the target water on the ground;
A raw water tank for temporarily storing target water to which the oxidizing agent is added by the oxidizing agent adding means;
Removal treatment means for removing the insoluble substances in the target water by filtering the target water sent from the raw water tank with a filtration device;
A water injection well for pouring the target water after being treated by the removal treatment means into the ground,
The recharging system according to claim 1, wherein the raw water tank has a capacity for storing target water according to a cleaning frequency and / or a cleaning time for backwashing the filtration device. The recharging system according to claim 1, wherein
The raw water tank has a capacity for temporarily storing the target water; and
A supply port for receiving the target water sent from the agent adding means, and a discharge port for sending the target water supplied and circulated from the supply port to the storage unit, and supplied from the supply port A recharging system comprising a reaction section configured such that a flow path length / volume until target water is discharged from the discharge port to the storage section is a required flow path length / volume. The recharge system according to claim 2,
It comprises target water flow control means for controlling the flow direction and / or flow velocity and / or flow rate of the target water flowing through the flow path from the supply port to the discharge port of the reaction unit. Recharge system. Add oxidant to the target water on the ground,
The target water to which the oxidant is added is temporarily stored in a raw water tank,
The target water sent from the raw water tank is filtered with a filtration device to 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,
The raw water tank is set with a capacity for storing the target water according to the washing frequency and / or washing time for backwashing the filtration device,
When recharging the target water into the ground from the water injection well is stopped and the filtration device is backwashed, the target water added with the oxidant is continuously sent to the raw water tank. Recharge method.

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