Neutralization device and neutralization method

Abstract

To adjust pH of wastewater containing suspended solids, with high precision.SOLUTION: A neutralization device 100 includes: a storage unit 130; a wastewater supply unit 120 that supplies wastewater to the storage unit; a pH detection unit 180 that detects pH of the wastewater supplied to the storage unit by the wastewater supply unit; a SS detection unit 182 that detects a concentration of SS contained in the wastewater supplied to the storage unit by the wastewater supply unit; an estimation unit 212 that estimates an amount of hydroxide ions eluted from the SS based on the concentration of the SS detected by the SS detection unit; a calculation unit 214 that calculates a first supply amount of a neutralizing agent based on the amount of hydroxide ions estimated by the estimation unit, calculates a second supply amount of the neutralizing agent based on the detected pH, and calculates a total supply amount by adding or subtracting the first supply amount and the second supply amount; and a supply control unit 216 that controls the neutralizing agent supply unit to supply a total supply amount of the neutralizing agent.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a neutralization device and a neutralization method. [Background technology]

[0002] Conventionally, turbid water generated during civil engineering construction work is discharged into rivers, lakes, oceans, etc. after purification treatment. Turbid water is wastewater that contains suspended solids (SS). Hereinafter, suspended solids may be referred to as "SS".

[0003] As a purification process for turbid water, a technology has been disclosed that includes a turbid water tank, a pH meter that measures the pH of the turbid water stored in the turbid water tank, and a carbon dioxide gas supplying device that supplies carbon dioxide gas to the turbid water discharged from the turbid water tank to neutralize it (for example, Patent Document 1). In the technology of Patent Document 1, the carbon dioxide gas supplying device supplies a set amount of carbon dioxide gas based on the measurement value of the pH meter. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2011-189339 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the technology for neutralizing turbid water based only on the pH of the turbid water as in Patent Document 1, there is a problem that the pH of the turbid water cannot be adjusted to a target value by the SS contained in the turbid water. To be more specific, when the amount of neutralizing agent that becomes the target value is determined based only on the pH of the turbid water and the determined amount of neutralizing agent is added to the turbid water, the turbid water temporarily reaches the target value, but the pH of the turbid water may change over time. This is presumably because the pH of the turbid water, for example, decreases due to the addition of the neutralizing agent, and the pH of the SS contained in the turbid water becomes relatively high, disrupting the pH equilibrium between the water and the SS in the turbid water, and alkaline components are dissolved from the SS into the turbid water.

[0006] In view of the above problems, the present disclosure aims to provide a neutralization device and a neutralization method capable of adjusting the pH of wastewater containing suspended solids with high precision. [Means for solving the problem]

[0007] In order to solve the above problems, a neutralization device according to one embodiment of the present disclosure includes a storage unit for storing wastewater containing suspended solids, a wastewater supply unit for supplying wastewater to the storage unit, a neutralizing agent supply unit for supplying a neutralizing agent to the storage unit, a pH detection unit for detecting the pH of the wastewater supplied to the storage unit by the wastewater supply unit, an SS detection unit for detecting the concentration of suspended solids contained in the wastewater supplied to the storage unit by the wastewater supply unit, an estimation unit for estimating an amount of hydroxide ions eluted from the suspended solids based on the concentration of the suspended solids detected by the SS detection unit, a calculation unit for calculating a first supply amount of neutralizing agent based on the amount of hydroxide ions estimated by the estimation unit, calculating a second supply amount of neutralizing agent based on the detected pH, and calculating a total supply amount by adding or subtracting the first supply amount and the second supply amount, and a supply control unit for supplying the total supply amount of neutralizing agent by controlling the neutralizing agent supply unit.

[0008] The estimation unit may estimate the amount of hydroxide ions eluted from the suspended solids by multiplying the concentration of the suspended solids by an elution coefficient.

[0009] In addition, the storage section may be provided with an outlet, and the wastewater supplied to the storage section by the wastewater supply section may flow toward the outlet, forming a flow of wastewater within the storage section, and the neutralizing agent supply section may supply a neutralizing agent to the flowing wastewater.

[0010] The neutralizing agent may also be carbon dioxide.

[0011] In order to solve the above problems, a neutralization method according to one embodiment of the present disclosure detects the pH of wastewater containing suspended solids, detects the concentration of the suspended solids contained in the wastewater, estimates the amount of hydroxide ions eluted from the suspended solids based on the detected concentration of the suspended solids, calculates a first supply amount of neutralizing agent based on the estimated amount of hydroxide ions, calculates a second supply amount of neutralizing agent based on the detected pH, calculates a total supply amount by adding or subtracting the first supply amount and the second supply amount, and supplies the total supply amount of neutralizing agent to a storage section that stores the wastewater. Effect of the Invention

[0012] According to the present disclosure, it is possible to adjust the pH of wastewater containing suspended solids with high precision. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram illustrating a neutralization device according to a first embodiment. [Diagram 2] FIG. 2 is a flowchart showing a process flow of the neutralization method according to the first embodiment. [Diagram 3] FIG. 3 is a diagram illustrating a neutralization device according to the second embodiment. [Figure 4] FIG. 4 is a table showing the experimental conditions, measured values, and calculated values ​​for the examples and comparative examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values ​​shown in the embodiments are merely examples for ease of understanding, and do not limit the present disclosure unless otherwise specified. In this specification and the drawings, elements having substantially the same functions and configurations are given the same reference numerals to avoid repeated explanation. In addition, elements not directly related to the present disclosure are not illustrated.

[0015] [First embodiment: Neutralization device 100] Fig. 1 is a diagram illustrating a neutralization device 100 according to a first embodiment. In Fig. 1, solid arrows indicate the flow of liquids and gases, such as wastewater, a neutralizing agent, and a flocculant. Also, in Fig. 1, dashed arrows indicate the flow of signals.

[0016] The neutralization apparatus 100 purifies wastewater (turbid water) containing suspended solids (SS). The neutralization apparatus 100 purifies wastewater generated in, for example, civil engineering construction work. Civil engineering construction work includes, for example, tunnel construction, subway construction, dam construction, revetment construction, and dredging work. The neutralization apparatus 100 is installed, for example, at the site of the civil engineering construction work.

[0017] In this embodiment, wastewater containing a cement component is taken as an example of wastewater. The cement component is, for example, a component of Portland cement. The cement component reacts with water and the like to contain calcium hydroxide (Ca(OH)2), magnesium hydroxide (Mg(OH)2), sodium hydroxide (NaOH), and potassium hydroxide (KOH). The pH of the wastewater containing the cement component is greater than 7, for example, 12 or more and 14 or less.

[0018] As shown in FIG. 1, the neutralization apparatus 100 includes, for example, a raw water tank 110, a wastewater supply section 120, a storage section 130, a neutralizing agent supply section 140, a flocculation section 150, a flocculating agent supply section 160, a sedimentation tank 170, a pH detection section 180, a first SS detection section 182, a second SS detection section 184, and a control device 200.

[0019] The raw water tank 110 is a tank for temporarily storing wastewater (raw water) generated at a civil engineering construction site.

[0020] The wastewater supply unit 120 supplies the wastewater stored in the raw water tank 110 to the storage unit 130. The wastewater supply unit 120 includes, for example, a pipe 112, a pump 122, and a pipe 124. The suction side of the pump 122 is connected to the raw water tank 110 through the pipe 112. The discharge side of the pump 122 is connected to the storage unit 130 through the pipe 124. When the pump 122 operates, the wastewater stored in the raw water tank 110 is supplied to the storage unit 130.

[0021] The storage unit 130 stores the wastewater supplied by the wastewater supply unit 120. The storage unit 130, for example, temporarily stores the wastewater. In this embodiment, the storage unit 130 is provided with, for example, a supply port 130a and a discharge port 130b. The storage unit 130 is, for example, a tank or a pipe.

[0022] The supply port 130a of the storage unit 130 is connected to the discharge side of the pump 122 of the wastewater supply unit 120 through a pipe 124. The discharge port 130b of the storage unit 130 is connected to the flocculation tank 152 of the flocculation unit 150 through a pipe 132.

[0023] When the pump 122 of the wastewater supply unit 120 operates, the wastewater stored in the raw water tank 110 is supplied into the storage unit 130 through the supply port 130a, and the supplied wastewater flows toward the discharge port 130b. As a result, a flow of wastewater is formed in the storage unit 130 from the supply port 130a toward the discharge port 130b.

[0024] The neutralizing agent supplying unit 140 supplies the neutralizing agent to the storage unit 130. This neutralizes the wastewater stored in the storage unit 130. In this embodiment, the neutralizing agent supplying unit 140 supplies the neutralizing agent to the wastewater flowing from the supply port 130a toward the discharge port 130b.

[0025] As described above, the pH of wastewater containing cement components is greater than 7. For this reason, the neutralizing agent is preferably one that lowers the pH. The neutralizing agent is, for example, carbon dioxide (gas). When the neutralizing agent is carbon dioxide, the neutralizing agent supply unit 140 supplies carbon dioxide bubbles having, for example, an average particle size (average bubble diameter) of 2.5 mm or less, preferably less than 1 mm. The neutralizing agent supply unit 140 includes, for example, a carbon dioxide storage unit 142, an aeration unit 144, a pipe 146, and a flow rate adjustment valve 148.

[0026] The carbon dioxide storage unit 142 stores carbon dioxide. The carbon dioxide storage unit 142 is, for example, a carbon dioxide cylinder. The carbon dioxide cylinder stores carbon dioxide compressed under high pressure.

[0027] The air diffusing unit 144 is provided on the bottom surface of the storage unit 130. A plurality of holes are formed in the air diffusing unit 144. The air diffusing unit 144 is, for example, plate-shaped, tubular, or rod-shaped. The air diffusing unit 144 may be made of, for example, a porous body. The porous body is made of, for example, resin, glass, ceramic, metal, or pumice.

[0028] The piping 146 connects the carbon dioxide storage section 142 and the aeration section 144. The flow rate adjustment valve 148 is provided on the piping 146. When the flow rate adjustment valve 148 is opened, the carbon dioxide stored in the carbon dioxide storage section 142 is supplied to the aeration section 144 through the piping 146. The carbon dioxide is then supplied to the wastewater in the storage section 130 through a plurality of holes in the aeration section 144. The opening degree of the flow rate adjustment valve 148 is adjusted by the control device 200, which will be described later. The adjustment of the opening degree of the flow rate adjustment valve 148 by the control device 200 will be described in detail later.

[0029] The flocculation section 150 flocculates SS contained in the wastewater supplied from the storage section 130. The flocculation section 150 includes, for example, a flocculation tank 152 and an agitator 154.

[0030] The coagulation tank 152 temporarily stores the wastewater supplied from the storage section 130. The agitator 154 agitates the wastewater stored in the coagulation tank 152.

[0031] The flocculant supply unit 160 supplies the flocculant to the flocculant tank 152. Therefore, the wastewater and the flocculant contained in the flocculant tank 152 are agitated by the agitator 154. As a result, the wastewater and the flocculant are mixed in the flocculant tank 152. Then, the SS contained in the wastewater is flocculated by the flocculant.

[0032] The flocculant may be, for example, one or both of an inorganic flocculant and an organic flocculant. The inorganic flocculant may be, for example, one or more selected from the group consisting of aluminum sulfate, polyaluminum chloride (PAC), ferric chloride, polyferric sulfate, and ferrous sulfate. The organic flocculant may be, for example, one or more selected from the group consisting of an anionic flocculant, a nonionic flocculant, and a cationic flocculant.

[0033] The flocculant supply unit 160 includes, for example, a flocculant storage unit 162 and a pump 164. The flocculant storage unit 162 stores the flocculant. The suction side of the pump 164 is connected to the flocculant storage unit 162 through a pipe 166. The discharge side of the pump 164 is connected to the flocculant tank 152 through a pipe 168. When the pump 164 operates, the flocculant stored in the flocculant storage unit 162 is supplied to the flocculation tank 152. The output of the pump 164 is adjusted by the control device 200. The adjustment of the output of the pump 164 by the control device 200 will be described in detail later.

[0034] The settling tank 170 is supplied with wastewater from the coagulation tank 152. The settling tank 170 retains the wastewater for a predetermined period of time. As described above, in the coagulation tank 152, the SS contained in the wastewater is coagulated by the coagulant. Therefore, while the wastewater is retained for the predetermined period of time in the settling tank 170, the coagulated SS contained in the wastewater settles to the bottom of the settling tank 170. The wastewater from which the SS has been removed (supernatant, treated water) is discharged into a river or the like.

[0035] The pH detection unit 180 detects the pH (hydrogen ion concentration exponent) of the wastewater supplied to the storage unit 130 by the wastewater supply unit 120. The pH detection unit 180 detects the pH of the wastewater before it is supplied to the storage unit 130. In this embodiment, the pH detection unit 180 detects the pH of the wastewater flowing through the pipe 124. The pH detection unit 180 is, for example, a pH meter.

[0036] The first SS detection unit 182 (SS detection unit) detects the concentration [g / L] of SS contained in the wastewater supplied to the storage unit 130 by the wastewater supply unit 120. The first SS detection unit 182 detects the concentration of SS contained in the wastewater before it is supplied to the storage unit 130. In this embodiment, the first SS detection unit 182 detects the concentration of SS contained in the wastewater flowing through the pipe 124. The first SS detection unit 182 is, for example, a turbidity meter.

[0037] The second SS detection unit 184 detects the concentration [g / L] of SS contained in the wastewater discharged from the storage unit 130 and before being supplied to the coagulation tank 152. In this embodiment, the second SS detection unit 184 detects the concentration of SS contained in the wastewater flowing through the pipe 132. The second SS detection unit 184 is, for example, a turbidity meter.

[0038] The control device 200 includes a central control unit 210 and a storage unit 220 .

[0039] The central control unit 210 is composed of a semiconductor integrated circuit including a CPU (Central Processing Unit). The central control unit 210 reads out programs and parameters for operating the CPU from a ROM. The central control unit 210 manages and controls the entire control device 200 in cooperation with a RAM as a work area and other electronic circuits.

[0040] The storage unit 220 is composed of a ROM, a RAM, a flash memory, a HDD, etc. The storage unit 220 stores programs and various data used by the central control unit 210. In this embodiment, the storage unit 220 stores in advance, for example, component information, elution information, neutralization information, and aggregation information.

[0041] The component information is, for example, information that associates a civil engineering construction site with the SS components contained in the wastewater.

[0042] The elution information is information that associates the components of the SS with the elution coefficient. The elution coefficient is determined in advance depending on the components of the SS. The elution coefficient is calculated based on the amount of hydroxide ions (OH - When the SS component is a cement component, the elution coefficient is, for example, more than 0.0 and less than 1.0, preferably more than 0.0 and 0.6 or less, more preferably more than 0.0 and 0.5 or less, even more preferably more than 0.0 and 0.4 or less, and even more preferably more than 0.0 and 0.2 or less.

[0043] The neutralization information is information that associates the amount of hydroxide ions [g / L] with the supply amount of neutralizing agent [g / L]. The supply amount of neutralizing agent is the amount of neutralizing agent required to bring the pH within the target neutralization range. The target neutralization range is, for example, one or both of the discharge reference value and the application range of the flocculant used in the flocculation section 150. The discharge reference value is, for example, pH 5.0 or more and pH 9.0 or less. The application range of the flocculant is, for example, pH 6.0 or more and pH 11.0 or less. The target neutralization range may be, for example, pH 5.0 or more and pH 11.0 or less.

[0044] The flocculation information is information that associates the concentration of SS [g / L] with the supply amount of flocculant [g / L]. The supply amount of flocculant is the amount of flocculant required to make the concentration of SS less than the target flocculation value. The target flocculation value is, for example, the discharge standard value.

[0045] In this embodiment, the central control unit 210 also functions as an estimation unit 212, a calculation unit 214, and a supply control unit 216.

[0046] The estimation unit 212 estimates the amount of hydroxide ions eluted from the SS based on the concentration [g / L] of the SS detected by the first SS detection unit 182. In this embodiment, the estimation unit 212 acquires information indicating the site of a civil engineering construction work, for example, based on location information or an operation input by a worker. Then, the estimation unit 212 acquires the components of the SS, for example, by referring to the component information. Next, the estimation unit 212 refers to the elution information stored in the storage unit 220 and reads out the elution coefficient associated with the acquired SS components. Next, the estimation unit 212 estimates the amount [g / L] of hydroxide ions eluted from the SS by multiplying the concentration of the SS detected by the first SS detection unit 182 by the read out elution coefficient.

[0047] The calculation unit 214 calculates a first supply amount of the neutralizing agent based on the amount of hydroxide ions estimated by the estimation unit 212. For example, the calculation unit 214 refers to the neutralization information stored in the storage unit 220 and reads out the supply amount associated with the estimated amount of hydroxide ions. In this way, the calculation unit 214 sets the read-out supply amount as the first supply amount.

[0048] Furthermore, the calculation unit 214 calculates a second supply amount of the neutralizing agent based on the pH detected by the pH detection unit 180. For example, the calculation unit 214 converts the detected pH into an amount of hydroxide ions. Then, the calculation unit 214 refers to the neutralization information stored in the storage unit 220 and reads out the supply amount associated with the converted amount of hydroxide ions. In this way, the calculation unit 214 sets the read-out supply amount as the second supply amount.

[0049] Then, the calculation unit 214 calculates the total supply amount by adding up the first supply amount and the second supply amount.

[0050] The calculation unit 214 may also calculate the supply amount of the flocculant based on the concentration [g / L] of SS detected by the second SS detection unit 184. For example, the calculation unit 214 refers to the flocculation information stored in the storage unit 220, and reads out the supply amount of the flocculant associated with the detected concentration of SS.

[0051] The supply control unit 216 controls the neutralizing agent supply unit 140 to supply the total supply amount of the neutralizing agent. In this embodiment, the supply control unit 216 adjusts the opening degree of the flow rate adjustment valve 148 of the neutralizing agent supply unit 140 to supply the total supply amount of the neutralizing agent.

[0052] Further, the supply control unit 216 controls the flocculant supply unit 160 to supply the flocculant in the amount calculated by the calculation unit 214. In this embodiment, the supply control unit 216 adjusts the output of the pump 164 of the flocculant supply unit 160 to supply the flocculant in the amount calculated by the calculation unit 214.

[0053] [Neutralization method] Next, a method for neutralizing wastewater using the neutralization device 100 will be described. FIG. 2 is a flow chart showing the flow of processing of the neutralization method according to this embodiment. As shown in FIG. 2, the neutralization method according to this embodiment includes, for example, a pH detection step S110, a SS concentration detection step S120, an estimation step S130, a first calculation step S140, a second calculation step S150, a total calculation step S160, a third calculation step S170, a neutralizing agent supply amount adjustment step S180, and a flocculant supply amount adjustment step S190. In the neutralization method according to this embodiment, the pumps 122 and 164 are operating. Also, the flow rate adjustment valve 148 is opened. Each step will be described below.

[0054] [pH detection step S110] In the pH detection step S110, the pH detection unit 180 detects the pH of the wastewater containing SS.

[0055] [SS concentration detection step S120] In the SS concentration detection step S120, the first SS detection unit 182 detects the concentration of SS contained in the wastewater, and the second SS detection unit 184 detects the concentration of SS contained in the wastewater.

[0056] [Estimation process S130] In the estimation step S130, the estimation unit 212 estimates the amount of hydroxide ions eluted from the SS based on the concentration of the SS detected by the first SS detection unit 182 in the SS concentration detection step S120.

[0057] [First calculation step S140] In the first calculation step S140, the calculation unit 214 calculates a first supply amount of the neutralizing agent based on the amount of hydroxide ions estimated in the estimation step S130.

[0058] [Second calculation step S150] In the second calculation step S150, the calculation unit 214 calculates a second supply amount of the neutralizing agent based on the pH detected in the pH detection step S110.

[0059] [Total calculation process S160] In the total calculation step S160, the calculation unit 214 calculates a total supply amount by adding the first supply amount calculated in the first calculation step S140 and the second supply amount calculated in the second calculation step S150.

[0060] [Third calculation step S170] In the third calculation step S170, the calculation unit 214 calculates the supply amount of the flocculant based on the concentration of SS detected by the second SS detection unit 184 in the SS concentration detection step S120.

[0061] [Neutralizing agent supply amount adjustment process S180] In the neutralizing agent supply amount adjustment step S180, the supply control unit 216 controls the neutralizing agent supply unit 140 to supply the total supply amount of neutralizing agent calculated in the total calculation step S160 to the storage unit 130. For example, the supply control unit 216 adjusts the opening degree of the flow rate adjustment valve 148 of the neutralizing agent supply unit 140 so that the total supply amount of neutralizing agent is supplied to the storage unit 130.

[0062] [Flocculant supply amount adjustment process S190] In the flocculant supply amount adjustment step S190, the supply control unit 216 controls the flocculant supply unit 160 to supply the flocculant at the supply amount calculated in the third calculation step S170 to the flocculation tank 152 of the flocculation unit 150. For example, the supply control unit 216 adjusts the output of the pump 164 of the flocculant supply unit 160 so that the flocculant at the supply amount calculated in the third calculation step S170 is supplied to the flocculation tank 152.

[0063] As described above, the neutralization apparatus 100 and the neutralization method according to the first embodiment can adjust the supply amount of the neutralizing agent by taking into account the concentration of hydroxide ions eluted from the SS contained in the wastewater in addition to the pH of the wastewater. Therefore, the neutralization apparatus 100 and the neutralization method according to the present embodiment can set the pH of the wastewater to be within the neutralization target range with high accuracy.

[0064] As described above, the estimation unit 212 may estimate the amount of hydroxide ions eluted from the SS by multiplying the concentration of the SS by the elution coefficient, which allows the estimation unit 212 to estimate the amount of hydroxide ions eluted from the SS by a simple process.

[0065] As described above, the storage section 130 may be provided with an outlet 130b, and the wastewater supplied to the storage section 130 by the wastewater supply section 120 may flow toward the outlet 130b to form a flow of wastewater in the storage section 130, and the neutralizing agent supply section 140 may supply the neutralizing agent to the flowing wastewater. This allows the neutralizing agent to be efficiently diffused in the wastewater without the need for an agitator. Therefore, the wastewater can be efficiently neutralized.

[0066] As described above, the neutralizing agent may be carbon dioxide. This makes it possible to neutralize wastewater while avoiding the need for personnel training to obtain the qualification of a supervisor of specific chemical substances and the need for cumbersome work such as filing a report to the Labor Standards Inspection Office.

[0067] [Second embodiment] In the above-described first embodiment, the storage unit 220 stores the elution information in advance, and the estimation unit 212 acquires the elution coefficient by referring to the elution information. However, the elution coefficient may be calculated at the site where the neutralization device 300 is installed.

[0068] Fig. 3 is a diagram illustrating a neutralization device 300 according to a second embodiment. In Fig. 3, solid arrows indicate the flow of liquids and gases such as wastewater, a neutralizing agent, and a flocculant. Also, in Fig. 3, dashed arrows indicate the flow of signals.

[0069] 3, the neutralization apparatus 300 includes, for example, a raw water tank 110, a wastewater supply section 120, a storage section 130, a neutralizing agent supply section 140, a flocculation section 150, a flocculation agent supply section 160, a settling tank 170, a pH detection section 180, a first SS detection section 182, a second SS detection section 184, a control device 200, and an analysis device 310. Note that components substantially the same as those in the neutralization apparatus 100 are denoted by the same reference numerals and will not be described.

[0070] The analyzer 310 extracts SS from the wastewater stored in the raw water tank 110. The analyzer 310 then mixes the extracted SS with pure water or ultrapure water and leaves it for a predetermined period of time. The analyzer 310 then detects the pH of the water mixed with the SS to calculate the elution coefficient.

[0071] In addition, in the second embodiment, the estimation unit 212 estimates the amount [g / L] of hydroxide ions eluted from the SS by multiplying the concentration of SS detected by the first SS detection unit 182 by the elution coefficient calculated by the analysis device 310.

[0072] As described above, the neutralization apparatus 300 according to the second embodiment includes the analysis device 310. This allows the elution coefficient to be calculated with high accuracy. Therefore, the neutralization apparatus 300 can improve the accuracy of estimating the amount of hydroxide ions eluted from the SS.

[0073] In addition, depending on the excavation location at the site of civil engineering construction work, the soil mixed into the wastewater may change. This causes the SS components contained in the wastewater to change. Therefore, the neutralization device 300 according to the second embodiment is equipped with the analysis device 310, so that the elution coefficient can be calculated with high accuracy even when the SS components contained in the wastewater change. Therefore, the neutralization device 300 can set the pH of the wastewater to the neutralization target range with high accuracy even when the SS components contained in the wastewater change.

[0074] The storage unit 220 of the neutralization device 300 according to the second embodiment does not need to store the component information and elution information in advance.

[0075] [Example] Wastewater containing suspended cement particles was prepared as wastewater in Examples 1 and 2. The wastewater in Example 1 had a pH of 12.54 and an SS concentration of 1500 ppm. The wastewater in Example 2 had a pH of 12.57 and an SS concentration of 1500 ppm.

[0076] Wastewater containing no SS was prepared for Comparative Examples 1 and 2. Comparative Example 1 had a pH of 12.68, and Comparative Example 2 had a pH of 12.26.

[0077] Then, for Example 1, Example 2, Comparative Example 1, and Comparative Example 2, the amount of neutralizing agent (carbon dioxide) was measured [g / L] when the neutralizing agent was supplied until the neutralization target value pH of 7 was reached.

[0078] In addition, the first supply amount [g / L], the second supply amount [g / L], and the total supply amount [g / L] were calculated for Example 1 and Example 2, assuming the elution coefficient to be 0.14. In addition, the second supply amount [g / L] for Comparative Example 1 and Comparative Example 2 was calculated.

[0079] Fig. 4 is a table showing the experimental conditions, measured values, and calculated values ​​according to the examples and comparative examples. As shown in Fig. 4, the actual measured value of the amount of neutralizer [g / L] in Example 1 was 1.10 g / L. The first supply amount in Example 1 was 0.27 g / L, the second supply amount was 0.84 g / L, and the total supply amount was 1.11 g / L. In Example 1, the difference between the actual measured value of the amount of neutralizer and the total supply amount was -0.01 g / L.

[0080] The measured value of the amount of neutralizing agent [g / L] in Example 2 was 1.15 g / L. The first supply amount in Example 2 was 0.27 g / L, the second supply amount was 0.90 g / L, and the total supply amount was 1.17 g / L. In Example 2, the difference between the measured value of the amount of neutralizing agent and the total supply amount was -0.02 g / L.

[0081] The measured value of the amount of neutralizing agent [g / L] in Comparative Example 1 was 1.15 g / L. The first supply amount in Comparative Example 1 was 0 g / L, the second supply amount was 1.16 g / L, and the total supply amount was 1.16 g / L. In Comparative Example 1, the difference between the measured value of the amount of neutralizing agent and the total supply amount was -0.01 g / L.

[0082] The measured value of the amount of neutralizing agent [g / L] in Comparative Example 2 was 0.44 g / L. The first supply amount in Comparative Example 2 was 0 g / L, the second supply amount was 0.44 g / L, and the total supply amount was 0.44 g / L. In Comparative Example 2, the difference between the measured value of the amount of neutralizing agent and the total supply amount was 0.00 g / L.

[0083] From the above results, it was confirmed that in Examples 1 and 2, the pH could not be lowered to the neutralization target value simply by supplying the second supply amount of neutralizing agent determined based on the pH.

[0084] In addition, it was found that the difference between the actual amount of the neutralizing agent and the calculated total supply amount was −0.02 g / L or less in Examples 1 and 2. Therefore, it was confirmed that in Examples 1 and 2, the pH can be set to the neutralization target value by supplying the first supply amount of the neutralizing agent determined based on the SS concentration in addition to the second supply amount determined based on the pH.

[0085] Furthermore, in Examples 1 and 2, it was confirmed that the difference between the measured amount of neutralizing agent and the calculated total supply amount was −0.02 g / L or less, which was substantially equal to the difference in Comparative Examples 1 and 2. From this result, it was confirmed that even in the case of wastewater containing SS, the pH of the wastewater can be set to the neutralization target value.

[0086] Although the embodiments have been described above with reference to the accompanying drawings, it goes without saying that the present disclosure is not limited to the above-described embodiments. It is clear that a person skilled in the art can think of various modified or altered examples within the scope of the claims, and it is understood that these also naturally belong to the technical scope of the present disclosure.

[0087] For example, in the above embodiment, the case has been described where the pH detection unit 180 detects the pH of the wastewater passing through the pipe 124. However, it is sufficient for the pH detection unit 180 to detect the pH of the wastewater before it is stored in the storage unit 130. The pH detection unit 180 may detect the pH of the wastewater stored in the raw water tank 110, for example.

[0088] Similarly, the above example shows the case where the first SS detection unit 182 detects the concentration of SS contained in the wastewater passing through the pipe 124. However, it is sufficient for the first SS detection unit 182 to detect the concentration of SS contained in the wastewater before it is stored in the storage unit 130. The first SS detection unit 182 may detect the concentration of SS contained in the wastewater stored in the raw water tank 110, for example.

[0089] In the above embodiment, the case where the pH of the wastewater supplied to the storage unit 130 is greater than 7 and the neutralizing agent is an acidic substance has been exemplified. However, when the pH of the wastewater supplied to the storage unit 130 is less than 7, the neutralizing agent may be an alkaline (basic) substance. In this case, the calculation unit 214 may subtract the first supply amount from the second supply amount. This makes it possible to adjust the pH of the wastewater containing SS with high accuracy.

[0090] In the above embodiment, the storage unit 130 has the supply port 130a and the discharge port 130b. However, it is sufficient that the storage unit 130 has at least the discharge port 130b. In this case, the storage unit 130 may have, for example, an open top.

[0091] In the above embodiment, the wastewater supply unit 120 includes the pipe 112, the pump 122, and the pipe 124. However, the configuration of the wastewater supply unit 120 is not limited as long as it can supply the wastewater stored in the raw water tank 110 to the storage unit 130. For example, when the water level in the raw water tank 110 is higher than the water level in the storage unit 130, such as when the raw water tank 110 is located above the storage unit 130, the wastewater supply unit 120 may be configured with a pipe connecting the raw water tank 110 and the storage unit 130. In this case, the wastewater stored in the raw water tank 110 is supplied to the storage unit 130 by a pressure difference.

[0092] In the above embodiment, the aeration section 144 having a plurality of holes is exemplified. However, it is sufficient that at least one hole is formed in the aeration section 144. When the aeration section 144 has one hole, the neutralizing agent supply section 140 may further include a stirring mechanism such as an ejector.

[0093] In the above embodiment, the neutralizing agent is carbon dioxide. However, the neutralizing agent may be any acidic substance. The neutralizing agent may be, for example, one or more selected from the group consisting of sulfuric acid, hydrochloric acid, and citric acid. In this case, the storage unit 130 may be provided with a stirring mechanism such as a line mixer.

[0094] Furthermore, the neutralization devices 100 and 300 may be provided with an adjustment device in the upstream of the storage unit 130, which adjusts the concentration of SS contained in the wastewater supplied to the storage unit 130 to 5000 ppm or less. This makes it possible to prevent the holes in the aeration unit 144 from being blocked by SS.

[0095] In the above embodiment, the neutralization apparatus 100, 300 includes the raw water tank 110, the flocculation unit 150, the flocculant supply unit 160, the settling tank 170, and the second SS detection unit 184. However, these configurations are not essential.

[0096] In the above first embodiment, the storage unit 220 of the neutralization device 100 stores component information in advance. However, the storage unit 220 of the neutralization device 100 does not need to store component information in advance. In this case, the estimation unit 212 may acquire the components of the SS in response to an operation input by an operator.

[0097] In the above embodiment, the storage unit 220 of the neutralization device 100, 300 stores neutralization information in advance. However, the storage unit 220 of the neutralization device 100, 300 does not have to store neutralization information in advance. In this case, the calculation unit 214 may calculate the first supply amount based on the amount of hydroxide ions and the type of neutralizing agent. The calculation unit 214 may also calculate the second supply amount based on the pH and the type of neutralizing agent.

[0098] In the above embodiment, the storage unit 220 of the neutralization device 100, 300 stores the aggregation information in advance. However, the storage unit 220 of the neutralization device 100, 300 does not have to store the aggregation information in advance. In this case, the calculation unit 214 may calculate the supply amount of the flocculant based on the concentration of SS and the type of the flocculant.

[0099] In addition, the wastewater contains hydrogen ions (H +a pH detection unit that detects a pH of the wastewater supplied to the storage unit by the wastewater supply unit; an SS detection unit that detects a concentration of the suspended matters contained in the wastewater supplied to the storage unit by the wastewater supply unit; an estimation unit that estimates an amount of hydrogen ions eluted from the suspended matters based on the concentration of the suspended matters detected by the SS detection unit; a calculation unit that calculates a first supply amount of the neutralizing agent based on the amount of hydrogen ions estimated by the estimation unit, calculates a second supply amount of the neutralizing agent based on the detected pH, and calculates a total supply amount by adding or subtracting the first supply amount and the second supply amount; and a supply control unit that controls the neutralizing agent supply unit to supply the total supply amount of the neutralizing agent calculated by the calculation unit.

[0100] It should be noted that the steps of the neutralization method of this specification do not necessarily need to be processed in chronological order according to the order described in the flow chart, and may include processing in parallel or by a subroutine. [Explanation of symbols]

[0101] 100 Neutralization device 120 Wastewater Supply Department 130 Storage unit 130b Outlet 140 Neutralizer Supply Section 180 pH detector 182 First SS detection unit (SS detection unit) 212 Estimation Department 214 Arithmetic section 216 Supply control section 220 Storage section 300 Neutralization device

Claims

1. A storage section for storing wastewater containing suspended solids; a wastewater supply unit for supplying the wastewater to the storage unit; A neutralizing agent supplying section for supplying a neutralizing agent to the storage section; a pH detection unit that detects a pH of the wastewater supplied to the storage unit by the wastewater supply unit; an SS detection unit that detects a concentration of the suspended solids contained in the wastewater supplied to the storage unit by the wastewater supply unit; an estimation unit that estimates an amount of hydroxide ions eluted from the suspended solids based on the concentration of the suspended solids detected by the SS detection unit; a calculation unit that calculates a first supply amount of the neutralizing agent based on the amount of hydroxide ions estimated by the estimation unit, calculates a second supply amount of the neutralizing agent based on the detected pH, and calculates a total supply amount by adding or subtracting the first supply amount and the second supply amount; a supply control unit that controls the neutralizing agent supply unit to supply the total supply amount of the neutralizing agent; A neutralization device comprising:

2. The neutralization apparatus according to claim 1 , wherein the estimation unit estimates an amount of hydroxide ions eluted from the suspended solids by multiplying a concentration of the suspended solids by an elution coefficient.

3. The storage section is provided with a discharge port, The wastewater supplied to the storage unit by the wastewater supply unit flows toward the outlet, thereby forming a flow of the wastewater in the storage unit, The neutralization apparatus according to claim 1 or 2, wherein the neutralizing agent supply unit supplies the neutralizing agent to the flowing wastewater.

4. The neutralization device according to claim 1 or 2, wherein the neutralizing agent is carbon dioxide.

5. Detecting the pH of the wastewater containing suspended solids; Detecting the concentration of the suspended solids contained in the wastewater; estimating the amount of hydroxide ions eluted from the suspended solids based on the detected concentration of the suspended solids; calculating a first supply amount of the neutralizing agent based on the estimated amount of hydroxide ions; Calculating a second supply amount of the neutralizing agent based on the detected pH; calculating a total supply amount by adding or subtracting the first supply amount and the second supply amount; The neutralization method further comprises supplying the total supply amount of the neutralizing agent to a storage section that stores the wastewater.

Images