Wastewater treatment system and wastewater treatment method

Abstract

To provide a wastewater treatment system and a wastewater treatment method capable of purifying air inside a tunnel and at the same time, appropriately neutralizing alkaline wastewater derived from, for example, cement, and performing neutralization treatment of alkaline wastewater at low cost.SOLUTION: A system comprises a filter device 4 that purifies air A1 containing exhaust gas, a concentrating device 5 that concentrates CO2 contained in air A2 purified by the filter device 4, and a supply device that supplies air A3 containing CO2 concentrated by the concentrating device to alkaline wastewater D.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a wastewater treatment system and a wastewater treatment method for treating alkaline wastewater derived from, for example, cement. [Background technology]

[0002] The inside of a tunnel is an almost completely sealed space with poor ventilation, so when constructing a tunnel, there is a risk that large amounts of exhaust gas and carbon dioxide emitted from construction vehicles such as concrete mixer trucks will accumulate.

[0003] In addition, when the inside of a tunnel is repaired with cement, alkaline wastewater is generated from the cement. In order to discharge this alkaline wastewater into public water bodies such as general rivers, it must be neutralized to meet the wastewater standard value (pH 5.8 to 8.6).

[0004] For this reason, a wastewater neutralization device has been known that collects and recovers acidic exhaust gases generated by vehicles traveling through a tunnel, and uses the recovered exhaust gas to neutralize alkaline wastewater generated outside or inside the tunnel (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-59847 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the wastewater neutralization device described in Patent Document 1 is configured to neutralize alkaline wastewater using exhaust gas generated by vehicles traveling through the tunnel, so there is a problem that the alkaline wastewater cannot be neutralized during tunnel repairs or construction work, which requires vehicles to stop traveling.This is the problem that the present invention aims to solve. [Means for solving the problem]

[0007] The present invention has been made in view of the above-mentioned circumstances and with the aim of solving these problems. The invention of claim 1 is a wastewater treatment system comprising a filter device for purifying air containing exhaust gas, a concentrating device for concentrating carbon dioxide contained in the air purified by the filter device, and a supply device for supplying the air containing carbon dioxide concentrated by the concentrating device to alkaline wastewater. The invention of claim 2 is a wastewater treatment system according to claim 1, characterized in that the supply device aerates the wastewater with air containing carbon dioxide concentrated in the concentrating device to neutralize the wastewater. The invention of claim 3 is the wastewater treatment system according to claim 1 or 2, characterized in that the supply device lowers the pH of the wastewater. The invention of claim 4 is a wastewater treatment method comprising a purification step of purifying air containing exhaust gas, a concentration step of concentrating carbon dioxide contained in the purified air, and a supply step of supplying the air containing the concentrated carbon dioxide to alkaline wastewater. The invention of claim 5 is the wastewater treatment method according to claim 4, characterized in that in the supplying step, air containing the carbon dioxide concentrated in the concentrating step is aerated into the wastewater to neutralize the wastewater. The invention of claim 6 is the wastewater treatment method according to claim 4 or 5, characterized in that in the supplying step, a pH of the wastewater is lowered. Effect of the Invention

[0008] According to the invention of claim 1 or 4, for example, by purifying air containing exhaust gas discharged from a work vehicle installed in a tunnel, and then concentrating the carbon dioxide contained in the air and supplying it to alkaline wastewater, for example, even when the tunnel is undergoing repair or construction, the air containing a large amount of carbon dioxide stored in the tunnel can be used to efficiently neutralize the alkaline wastewater. Therefore, the air in the tunnel can be purified, and at the same time, alkaline wastewater derived from cement can be appropriately neutralized, and the neutralization treatment of alkaline wastewater can be performed at low cost. According to the invention of claim 2 or 5, air containing concentrated carbon dioxide is aerated into alkaline wastewater to neutralize the alkaline wastewater, thereby enabling efficient neutralization treatment of the alkaline wastewater. According to the invention of claim 3 or 6, by lowering the pH of alkaline wastewater, it becomes easier to discharge the wastewater into public water areas. [Brief description of the drawings]

[0009] [Figure 1] 1 is a system configuration diagram of a wastewater treatment system according to an embodiment of the present invention. [Diagram 2] 4 is a flowchart showing a treatment method performed by the wastewater treatment system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is a wastewater treatment system. Specifically, the wastewater treatment system 1 is a neutralization treatment system for neutralizing alkaline wastewater D derived from cement, for example. As shown in FIG. 1, the wastewater treatment system 1 is equipped with a filter device 4 connected to a muffler M of a work vehicle V parked inside a tunnel T. As the filter device 4, a stationary diesel black smoke filter (product name: Heavy Duty Power PC-20HF, manufactured by Ryuki Engineering Co., Ltd.) or the like is used. Specifically, the filter device 4 adsorbs and purifies almost 100% of the diesel black smoke (exhaust gas) and the like exhausted from the muffler M of the work vehicle V.

[0011] The filter device 4 includes an intake chamber 4a that draws in air A1 containing diesel black smoke (exhaust gas) and high-concentration CO2 exhausted from a muffler M of a work vehicle V, a high-performance filter 4b that purifies the air containing diesel black smoke drawn in by the intake chamber 4a, and a blower 4c that exhausts air A2 from which the black smoke has been purified by the high-performance filter 4b. A manometer (differential pressure gauge) 4d is attached to the blower 4c, and the manometer 4d is configured to be capable of measuring the pressure difference between the intake chamber 4a and the blower 4c. A duct 4e is attached to the intake chamber 4a and is inserted into the muffler M of the work vehicle V to draw the air A1 containing diesel black smoke exhausted from the muffler M into the intake chamber 4a.

[0012] Furthermore, an exhaust duct 4f is connected to the blower 4c of the filter device 4, and the downstream side of this exhaust duct 4f is connected to a concentrator 5 that concentrates the CO2 contained in the air A2 purified by the filter device 4. As the concentrator 5, a CO2 concentrator (product name: Zeocollect, manufactured by Daifuku Kogyo Co., Ltd.) or the like is used. Specifically, this concentrator 5 utilizes the characteristics of ferrierite (a type of zeolite) produced in Shimane Prefecture that adsorbs CO2, and sends the air A2 containing CO2 purified by the filter device 4 into two cylindrical cartridges 5a and 5b filled with crushed ferrierite, and repeats pressurization and decompression to concentrate the CO2 contained in this air A2 10 to 20 times, and stores the air A3 containing high-purity CO2 in a storage tank 5c.

[0013] A supply device 6 is attached to the downstream side of the storage tank 5c for supplying the air A3 containing high purity CO2 stored in the storage tank 5c to the outside. The supply device 6 has a supply duct 6a connected to the storage tank 5c on the upstream side, and a blower 6b such as a compressor is attached to the middle part of the supply duct 6a. The downstream side of the supply duct 6a is inserted and attached in alkaline wastewater D stored in a storage tank 7, and the air A3 containing high purity CO2 is aerated from the supply duct 6a into the wastewater D to lower the pH of the wastewater D and neutralize it.

[0014] Here, the alkaline wastewater D is mainly generated from the shotcrete and lining concrete used during the excavation of the tunnel T and during repairs and construction inside the tunnel T after completion, but is also generated by elution from calcium contained in some of the natural ground. The neutralization treatment of the wastewater D stored in the reservoir 7 is aimed at lowering the pH of the wastewater D, and it is preferable to supply a large amount of air A3 containing high purity CO2 stored in the storage tank 5c until the pH of the wastewater D reaches a wastewater standard value (pH 5.8 to pH 8.6) that can be discharged into a public water area P such as a general river, if possible. The wastewater D neutralized to this wastewater standard value can be discharged from the pump 8 installed in the storage tank 7 through the drain pipe 9 into a public water area P such as a general river.

[0015] Next, a wastewater treatment method using the wastewater treatment system 1 according to the present invention will be described with reference to FIG.

[0016] <Preparation process> The duct 4e of the filter device 4 is inserted into the muffler M of the work vehicle V installed inside the tunnel T, and the air A1 containing black diesel smoke exhausted from the muffler M of the work vehicle V is drawn into the intake chamber 4a of the filter device 4 (step S1).

[0017] <Cleaning process> Then, the blower 4c of the filter device 4 is driven to supply the air A1 containing diesel black smoke exhausted from the muffler M of the work vehicle V to the high-performance filter 4b of the filter device 4. Then, as the air A1 passes through the high-performance filter 4b, nearly 100% of the diesel black smoke contained in this air A1 is adsorbed and purified (step S2).

[0018] <Concentration process> Next, the air A2 purified by the filter device 4 is supplied to the concentrator 5 via the exhaust duct 4f, and then sent to two cartridges 5a, 5b of the concentrator 5, where pressure and pressure are repeatedly increased and decreased, so that the CO2 contained in the air A2 is concentrated 10 to 20 times to produce air A3 containing highly pure CO2, which is then stored in the storage tank 5c (step S3).

[0019] <Supply process> Furthermore, the blower 6b of the supply device 6 is driven to aerate the air A3 stored in the storage tank 5c of the concentrating device 5 through the supply duct 6a into the alkaline wastewater D stored in the storage tank 7, thereby lowering the pH of the wastewater D and neutralizing it (step S4).

[0020] <Discharge process> Thereafter, if a large amount of air A3 has been recovered and this air A3 has been used to neutralize the wastewater D to the wastewater standard value at which it can be discharged into a public water area P, the wastewater D is pumped up from the storage tank 7 using a pump 8 through a drainage pipe 9, and then discharged into a public water area P, such as a general river (step S5).

[0021] <Action and effect> In general, the air A1 in the tunnel T is filled with a large amount of exhaust gas and CO2 emitted by the driving of construction vehicles, such as concrete mixer trucks, used in repair work in the tunnel T. In addition, exhaust gas generally contains NO X , S.O. X Since the air A1 contains harmful substances such as diesel smoke and CO, it is necessary to forcibly release the air A1 containing black diesel smoke exhausted from the muffler M of the work vehicle V installed inside the tunnel T outside the tunnel T to circulate it. In particular, the air A1 inside the tunnel T contains a large amount of CO2, and CO2 has the property of being acidic when dissolved in water.

[0022] On the other hand, the main sources of pollution are sprayed concrete and lining concrete during the excavation of Tunnel T and during repairs and construction inside Tunnel T after completion. Also, a large amount of alkaline wastewater D is generated due to leaching of calcium contained in some of the ground. In order to discharge this wastewater D into public water area P, it is necessary to neutralize it to a wastewater standard value, for example, pH 5.8 to pH 8.6.

[0023] Therefore, in one embodiment of the present invention configured as described above, the air A1 containing exhaust gas exhausted from the muffler M of the work vehicle V installed in the tunnel T is purified by the filter device 4 to adsorb and purify diesel black smoke and the like, and then the CO2 contained in the purified air A2 is concentrated and then supplied to the alkaline wastewater D to lower the pH. As a result, even when the tunnel T is being repaired or constructed, for example, it is possible to reduce the amount of CO2 emitted from the work vehicle V installed in the tunnel T, and the alkaline wastewater D can be efficiently neutralized using the air containing a large amount of CO2 stored in the tunnel T. Therefore, the air A1 in the tunnel T can be purified, and at the same time, the CO2 floating in the tunnel T can be effectively utilized without being released into the outside air.

[0024] Furthermore, since the system is configured to use CO2 in the atmosphere floating inside Tunnel T to neutralize alkaline wastewater D, for example from cement, it can neutralize alkaline wastewater D at a lower cost than conventional methods that use liquefied carbon dioxide gas or dilute sulfuric acid.

[0025] In addition, the air A1 in the tunnel T may be filled with exhaust gas from vehicles passing through before repair or construction work, or from construction vehicles during repair or construction work. The exhaust gas-containing air A1 in the tunnel T contains NO X , S.O. XTherefore, before concentrating the CO2 in the air A1 containing the exhaust gas from the work vehicle V installed in the tunnel T, the NO2 in this air A1 is concentrated. X , S.O. X The carbon dioxide contained in the air A1 can be purified while harmful substances such as CO and CO are removed in the concentrating device 5. As a result, by neutralizing the alkaline wastewater D with the air A2 containing the purified CO2, it is possible to appropriately prevent contamination by harmful substances and the like that may occur when the alkaline wastewater D is neutralized.

[0026] Furthermore, the air A3 enriched in CO2 by the concentrator 5 is aerated through the supply tact 6a of the supply device 6 into the alkaline wastewater D stored in the storage tank 7 for neutralization, so that the neutralization of the alkaline wastewater D can be efficiently performed with a smaller supply amount of air A3. The highly pure air A3 enriched in CO2 can lower the pH of the alkaline wastewater D. Depending on the supply amount (recovery amount) of the air A3, the wastewater D can be neutralized to a wastewater standard value that allows it to be discharged into a public water area P, and the neutralized wastewater D can be safely discharged into the public water area P.

[0027] Although one embodiment of the present invention has been described above, it goes without saying that the present invention is not limited to the above embodiment. For example, the intake device 2, recovery device 3, purification device 4, concentration device 5, and supply device 6, which constitute the wastewater treatment system 1 according to the present invention, may have any configuration as long as the processing performed by these devices can be performed appropriately. [Explanation of symbols]

[0028] 1 Wastewater treatment system 4. Filter device 4a Intake chamber 4b High performance filter 4c Blower 4d Manometer 4e Duct 4f Exhaust duct 5 Concentrator 5a,5b Cartridge 5c Storage tank 6 Feeding device 6a Supply duct 6b blower 7. Reservoir 8. Pump 9 Drain pipe V Work vehicle M Muffler D Drainage T-Tunnel P Public waters A1 Exhaust gas and air containing high concentrations of CO2 A2 Air containing purified CO2 A3 Air containing high purity CO2

Claims

1. A filter device for purifying air containing exhaust gas; A concentrator for concentrating carbon dioxide contained in the air purified by the filter device; A supply device that supplies the air containing carbon dioxide concentrated by the concentrator to the alkaline wastewater; A wastewater treatment system comprising:

2. The supply device aerates the wastewater with air containing the carbon dioxide concentrated in the concentrator to neutralize the wastewater.

2. The wastewater treatment system according to claim 1.

3. The supply device reduces the pH of the wastewater.

3. The wastewater treatment system according to claim 1 or 2.

4. A purification step of purifying air containing exhaust gas; A concentrating step of concentrating carbon dioxide contained in the purified air; A supplying step of supplying the concentrated carbon dioxide-containing air to alkaline wastewater; A wastewater treatment method comprising:

5. The supplying step includes aerating the wastewater with air containing the carbon dioxide concentrated in the concentrating step to neutralize the wastewater.

5. The wastewater treatment method according to claim 4.

6. The supplying step reduces the pH of the wastewater.

6. The wastewater treatment method according to claim 4 or 5.

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