Wastewater treatment system

Abstract

To provide a wastewater treatment system capable of suppressing a leakage of environmentally hazardous substances from wastewater discharged from fire extinguishing facility that uses water, such as sprinklers and fire hydrants that are activated during ignition or fire.SOLUTION: A ceiling of the storage warehouse 1 includes a sprinkler 2, while a drainage channel is formed around the perimeter of the floor of the storage warehouse 1, which is connected to the waste water channel 11. The wastewater channel 11 has a first pump 12 and a wastewater storage tank 13, and at the rear of the wastewater storage tank 13 is a second pump 14, an activated carbon column 15 as removal means, a zeolite column 16 and an ion exchange resin column 17, in sequence, which are open to the external environment through a discharge channel 18.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a wastewater treatment system installed in a storage warehouse for power storage devices such as lithium-ion batteries or lithium-ion capacitors, and particularly to a wastewater treatment system capable of suppressing leakage of environmentally harmful substances from wastewater discharged from fire-fighting equipment such as sprinklers and fire hydrants that operate during ignition and fires.

Background Art

[0002] Lithium-ion batteries, lithium-ion battery packs composed of a plurality of these, lithium-ion capacitors (hereinafter referred to as lithium-ion batteries, etc.) are widely used as power sources for various household appliances and EVs, and their application fields and usage amounts are expected to further expand. Since these lithium-ion batteries, etc. contain a flammable non-aqueous electrolyte, they are treated as dangerous substances under the Fire Service Act, and regulations are provided on the amount that can be stored. However, in the future, the usage amount of lithium-ion batteries, especially batteries for EVs, is expected to increase, and it is necessary to prepare facilities for storing a large amount of lithium-ion batteries, etc. As the current regulations stand, it is necessary to build many warehouses with limited scale, but by installing fire-fighting equipment such as sprinklers in the storage warehouse, it has been considered to relax the regulations on the storage amount of lithium-ion batteries, etc.

Summary of the Invention

Problems to be Solved by the Invention

[0003] In the case where the above-mentioned fire extinguishing equipment is installed, when a fire breaks out from a lithium ion battery or the like, the components used in the positive electrode, negative electrode, electrolyte, etc. in the battery will spray out from the battery, etc., and fill the warehouse. When the fire is extinguished with water by a sprinkler or the like, the components of the positive electrode, negative electrode, electrolyte, etc. will be released directly into the external environment. This waste liquid contains, for example, Li, F (fluorine), hydrogen fluoride, Co, Mn, Ni, Cu, Al, Fe, P, electrolyte (organic solvent), etc. due to the components. These components also contain environmentally harmful substances that are subject to wastewater regulations, and in particular, HF (hydrogen fluoride) must be kept below the environmental regulation value. However, existing storage warehouses are often not equipped with wastewater treatment equipment, and even if fire extinguishing equipment such as sprinklers is installed in a storage warehouse that does not have such wastewater treatment equipment, there is a problem that wastewater treatment cannot be performed as it is. In particular, lithium-ion batteries and other such materials are often transported by ship, and storage warehouses for these materials are often built near ports or rivers, meaning that wastewater generated during firefighting is likely to be discharged into rivers and oceans without being treated. For this reason, measures against environmentally hazardous substances resulting from lithium-ion batteries and other such materials are necessary, but since these are merely facilities for safety measures in storage warehouses, it is desirable that they be simple and inexpensive.

[0004] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a wastewater treatment system that can suppress the leakage of environmentally harmful substances from wastewater discharged from fire extinguishing equipment such as sprinklers and fire hydrants that are activated in the event of ignition of lithium ion batteries or the like and an associated fire. [Means for solving the problem]

[0005] In view of the above object, the present invention provides a wastewater treatment system for a storage warehouse for storing lithium ion batteries or lithium ion storage devices, the storage warehouse being equipped with a fire extinguishing system, the wastewater treatment system including a wastewater storage tank for wastewater used when the fire extinguishing system is activated (Invention 1).

[0006] According to this invention (Invention 1), by storing wastewater originating from water released from fire extinguishing equipment such as sprinklers and fire hydrants that are activated in the event of ignition of lithium ion batteries or the like or an associated fire in a wastewater tank, this wastewater is not directly released into the external environment. Therefore, by moving the wastewater tank and then treating the wastewater, it is possible to prevent the leakage of environmentally harmful substances caused by lithium ion batteries, etc.

[0007] In the above invention (Invention 1), it is preferable that the wastewater storage tank is portable (Invention 2).

[0008] According to this invention (Invention 2), the wastewater discharged from the storage warehouse is stored in a wastewater tank, and then the wastewater tank is transported to another location for water treatment. This prevents the wastewater from being released directly into the external environment, thereby preventing the leakage of environmentally harmful substances caused by lithium-ion batteries, etc.

[0009] In the above invention (Invention 1), it is preferable to provide a removal means for removing environmentally harmful substances downstream of the wastewater storage tank (Invention 3). Also, in the above invention (Invention 3), it is preferable that the environmentally harmful substances originate from the lithium ion battery or lithium ion power storage device (Invention 4).

[0010] According to such inventions (Inventions 3 and 4), wastewater derived from water discharged from a fire extinguishing system is stored in a wastewater storage tank, and then this wastewater is treated with a removal means, thereby reducing the amount of environmentally harmful substances, and even if this treated wastewater is discharged into the external environment, leakage of environmentally harmful substances can be suppressed.

[0011] In the above inventions (Inventions 3 and 4), it is preferable that the removal means comprises one or more selected from a zeolite column, an ion exchange resin tower, and an activated carbon tower (Invention 5).

[0012] According to this invention (Invention 5), it is possible to reduce hydrofluoric acid and fluorine-based compounds, which are major environmentally harmful substances originating from lithium-ion batteries or lithium-ion power storage devices, and to suppress leakage of hydrofluoric acid, which is an environmentally harmful substance, even if the treated wastewater is released into the external environment. Effect of the Invention

[0013] According to the wastewater treatment system of the present invention, a wastewater storage tank for wastewater used when the fire extinguishing equipment in the storage warehouse for lithium ion batteries or lithium ion storage devices is activated is provided, and by storing wastewater derived from water discharged from fire extinguishing equipment such as sprinklers and fire hydrants in the wastewater storage tank, this wastewater is not directly discharged to the external environment, and therefore leakage of environmentally hazardous substances caused by lithium ion batteries, etc. can be suppressed. In particular, by providing a removal means for removing environmentally hazardous substances downstream of the wastewater storage tank, environmentally hazardous substances such as hydrofluoric acid and fluorine-based compounds (including organic fluorine compounds such as PFAS) caused by lithium ion batteries or lithium ion storage devices can be reduced, and leakage of environmentally hazardous hydrofluoric acid can be suppressed even if the treated wastewater is discharged to the external environment. [Brief description of the drawings]

[0014] [Figure 1] 1 is a schematic diagram illustrating a wastewater treatment system according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The wastewater treatment system of the present invention will be described in detail below with reference to the accompanying drawings.

[0016] <Wastewater treatment system> Fig. 1 shows a wastewater treatment system according to one embodiment of the present invention. In Fig. 1, reference numeral 1 denotes a storage warehouse for lithium ion batteries or lithium ion storage devices (lithium ion batteries in this embodiment), and a sprinkler 2 is provided on the ceiling of this storage warehouse 1 as a fire extinguishing system that uses water, while a drain (not shown) is formed on the periphery of the floor of the storage warehouse 1, and this drain is connected to a wastewater channel 11.

[0017] There are no particular limitations on the extinguishing agent used in the sprinkler 2 as the fire extinguishing equipment, so long as it can extinguish the fire caused by lithium ion batteries, but water or an extinguishing agent for electrical fires is used. Note that when an extinguishing agent is used, water is used to clean the interior of the storage warehouse 1 after the fire has been extinguished, and this water becomes wastewater.

[0018] The wastewater channel 11 is provided with a first liquid-transfer pump 12 and a wastewater storage tank 13, and a second liquid-transfer pump 14 and an activated carbon tower 15, a zeolite column 16, and an ion-exchange resin tower 17 (mixed ion-exchange resin tower) as removal means are sequentially provided downstream of the wastewater storage tank 13, and the wastewater channel 11 is open to the outside environment through a discharge channel 18. In this embodiment, the discharge channel 18 is provided with a return channel 19 communicating with the wastewater storage tank 13, and the discharge channel 18 can be switched between the outside environment side and the return channel 19 side based on the measured values ​​of a pH meter and a conductivity meter (not shown). The wastewater storage tank 13 and the removal means (activated carbon tower 15, zeolite column 16, ion-exchange resin tower 17) constitute a wastewater treatment system.

[0019] In the removal means of the wastewater treatment system as described above, the activated carbon tower 15 is effective for removing fluorine, organic solvents, and cations and anions in water, and the zeolite column 16 is effective for removing cations in water. Furthermore, the ion exchange resin tower 17 is filled with anion exchange resin and cation exchange resin in a layered or mixed state. Since the wastewater W contains a large amount of cationic harmful substances, it is preferable that the ion exchange resin tower 17 is filled with 40% or more (volume ratio), and specifically, the cation exchange resin:anion exchange resin=about 40:60-70:30 (volume ratio) is preferable.

[0020] The removal means does not need to be a three-stage structure of the activated carbon tower 15, the zeolite column 16, and the ion exchange resin tower 17, but may be provided with at least one or two or more of these. In particular, it is preferable to use the activated carbon tower 15, and sufficient performance can be expected even with the activated carbon tower 15 and the zeolite column 16.

[0021] <Wastewater treatment method> Next, a wastewater treatment method using the wastewater treatment system of this embodiment having the above-mentioned configuration will be described below.

[0022] If a lithium-ion battery stored in the storage warehouse 1 ignites and the resulting flame is detected, the fire is extinguished by spraying a fire extinguishing agent (water) from the sprinklers 2 installed on the ceiling. The water used for this fire extinguishing flows into a wastewater channel 11 as wastewater W from a drain (not shown) formed on the periphery of the floor of the storage warehouse 1, and is stored in a wastewater tank 13 via a first liquid delivery pump 12.

[0023] In addition to the electrode material, lithium ion batteries use a non-aqueous electrolyte in which lithium salts such as lithium hexafluorophosphate are dissolved in a mixed solution of chain carbonates such as methyl carbonate (DMC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC). When the casing of the lithium ion battery collapses due to ignition, these components are partially thermally denatured and spread within the storage warehouse 1, and are dissolved by water from the sprinkler 2. For this reason, the wastewater W contains ionized cationic and anionic components of environmentally harmful substances such as iron, copper, manganese, and phosphorus, particularly hydrochloric acid and other fluorine compound ions, and also various particles of metals, plastics, etc. are dispersed.

[0024] Therefore, the second liquid delivery pump 14 is operated to supply the wastewater W stored in the wastewater storage tank 13 to the removal means. In this embodiment, this removal means has a three-stage configuration of an activated carbon tower 15, a zeolite column 16, and an ion exchange resin tower 17. First, in the activated carbon tower 15, fluorine, organic solvent, and cations and anions in the water are removed, as well as impurities and solid particles. Next, in the zeolite column 16, cations in the water are further removed. Furthermore, in this embodiment, an ion exchange resin tower 17 is provided in the last stage to remove remaining cations and anions, thereby obtaining treated water W1.

[0025] The quality of the treated water W1 is regulated to 8 mg / L or less for fluorine and fluorine compounds when discharged to public waters (except for the sea area) and 15 mg / L or less when discharged to the sea area. Cu: 3 mg / L or less, Fe: 10 mg / L or less, Mn: 10 mg / L or less, and P: 16 mg / L or less. Therefore, the treatment capacity of the activated carbon tower 15, the zeolite column 16, and the ion exchange resin tower 17 may be of a size (volume) that can sufficiently remove cations and anions, etc., depending on the floor area of ​​the storage warehouse 1 and the water discharge performance of the sprinkler 2. However, since this wastewater treatment system is not a regular facility but an emergency facility for use in the event of a fire, it is preferable to make each of them as small as possible (for example, a volume of 100 L or less, particularly about 50 L or less) in terms of installation cost and installation space.

[0026] In this embodiment, a pH meter is provided in the drainage channel 18 to measure the pH of the treated water W1, and the concentration of hydrofluoric acid is estimated from the correlation between the concentration of hydrofluoric acid calculated in advance and the pH of the wastewater W, and compliance with the above regulations is judged. Also, a conductivity meter is provided to measure the conductivity of the treated water W1, and compliance with the above regulations is judged comprehensively from the correlation between the concentrations of Cu, Fe, Mn, P, etc. calculated in advance and the conductivity. If it is estimated that the above regulations are satisfied, the treated water W1 is discharged through the discharge channel 18 as the external environment side. On the other hand, if it is estimated that the above regulations are not satisfied, the discharge channel 18 is switched to the return channel 19 side, and the treated water W1 is returned to the wastewater tank 13 for circulating treatment.

[0027] According to the wastewater treatment system of this embodiment, it is possible to minimize leakage of environmentally harmful substances from wastewater originating from water released from fire extinguishing equipment such as sprinklers and fire hydrants that are activated in the event of ignition of lithium ion batteries or the like or an associated fire.

[0028] Although the present invention has been described above based on the above embodiment, the present invention is not limited to the above embodiment and various modifications are possible. For example, in the above embodiment, the removal means is provided at the rear of the wastewater storage tank 13, but by providing only the wastewater storage tank 13 in the storage warehouse and making the wastewater storage tank 13 portable, the wastewater W may be stored in the wastewater storage tank 13 after the fire extinguishing equipment is operated, and then transported together with the wastewater storage tank 13 to be treated separately in another wastewater treatment facility. In addition, either the pH meter or the electric conductivity meter may be used, and if the removal means has sufficient removal capacity, the return path 19 may not be provided. Furthermore, the first liquid delivery pump 12 may not be provided in the wastewater storage tank 13 if the wastewater W flows into the wastewater storage tank from the drain with a height difference. [Explanation of symbols]

[0029] 1 Storage warehouse 2. Sprinklers (fire extinguishing equipment) 11 Abandoned Canal 12 First liquid delivery pump 13 Wastewater storage tank 14 Second liquid delivery pump 15 Activated carbon tower (removal means) 16 Zeolite column (removal means) 17 Ion exchange resin tower (removal means) 18 Exhaust channel 19 Circulation Channel W Wastewater W1 Treated water

Claims

1. A wastewater treatment system for a storage warehouse for storing lithium ion batteries or lithium ion storage devices, the storage warehouse being equipped with a fire extinguishing system, the wastewater treatment system comprising a wastewater storage tank for wastewater used when the fire extinguishing system is activated.

2. 10. The wastewater treatment system of claim 1, wherein the wastewater storage tank is portable.

3. 2. The wastewater treatment system according to claim 1, further comprising a removal means for removing environmentally harmful substances downstream of said wastewater storage tank.

4. The wastewater treatment system of claim 3 , wherein the environmentally harmful substances are caused by the lithium ion battery or lithium ion power storage device.

5. 5. The wastewater treatment system according to claim 3, wherein the removing means comprises one or more selected from a zeolite column, an ion exchange resin tower, and an activated carbon tower.

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