Treatment method of high-salt high-TOC (total organic carbon) wastewater

Abstract

The invention relates to a method for treating high-salinity high-TOC (total organic carbon) wastewater, which is used for directly treating high-salinity wastewater, particularly high-organic-matter high-salinity wastewater by combining a high-temperature melting oxidation technology, does not generate mother liquor, and is low in cost and simple to operate. The vertical furnace and the high-temperature melting oxidation furnace are coupled, solid-liquid separation is achieved, and the problems that organic matter is wrapped by solid salt, and the organic matter is not thoroughly removed are solved.

Description

Technical Field

[0001] The invention relates to a method for treating high-salt and high-TOC wastewater, belonging to the technical field of wastewater treatment. Background Art

[0002] A large amount of salt-containing wastewater is generated during the chemical production process. According to incomplete statistics, the pesticide industry produces about 50 million tons of high-salt wastewater each year, and the printing and dyeing industry produces a total of 2.43 billion tons of printing and dyeing wastewater each year. The amount of high-salt and high-TOC wastewater is large. The current treatment method for high-salt and high-TOC wastewater is: use multi-effect evaporation or MVR to separate the brine first, the water is discharged after deep treatment, and the salt is treated by high-temperature molten oxidation and used as a downstream product. However, whether it is multi-effect evaporation or MVR, after the equipment has been running for a period of time, there will be problems such as decreased evaporation, unstable salt output, and decreased salt quality, which will cause the equipment to be unable to continue to operate and can only be stopped for cleaning, and the washing effect will discharge a large amount of mother liquor. The mother liquor has high salt and organic content. At present, the discharged mother can only be temporarily stored in the mother liquor pool. After a long time, the company cannot bear it, and once it leaks, there is a huge environmental risk.

[0003] At present, the conventional treatment method for these high-concentration mother liquors is solidification. A rake dryer or other drying equipment is used, the mother liquor is added to the drying equipment, and the water and salt are separated under a vacuum state. This method can reduce the amount of mother liquor, but the solid material obtained has a high organic content and the salt has no obvious crystal form. The solid salt obtained by this method has not been effectively treated, especially with the implementation of the new landfill standard "Hazardous Waste Landfill Pollution Control Standard (GB 18598-2019)". The solid material obtained by this method has a high organic content and a high soluble salt content, which does not meet the standards for flexible landfill. If it is rigidly landfilled, the disposal cost is high and it is difficult for the company to bear. In addition, landfill is also a waste of resources.

[0004] Therefore, there is an urgent need for a new method for treating high-salt and high-TOC wastewater with low cost and without the production of high-salt and high-organic mother liquor. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a method for treating high-salt and high-TOC wastewater.

[0006] The present invention directly treats high-salt and high-TOC waste liquid through the processes of dehydration, organic matter removal, and organic matter oxidation removal. The vertical furnace and the high-temperature molten oxidation furnace are combined. The high-salt and high-TOC waste liquid is dehydrated in the vertical furnace, and the water enters the exhaust gas treatment system along with the flue gas. The solid salt with the organic matter initially removed after solid-liquid separation falls into the high-temperature molten oxidation furnace below the vertical furnace. The solid salt is heated to become molten salt, and the organic matter wrapped in the solid salt is completely removed. The obtained refined salt product meets the use requirements of downstream chlor-alkali enterprises and has obvious economic and environmental protection value.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0008] A method for treating high-salt and high-TOC wastewater comprises: atomization, organic matter removal, organic matter oxidation removal, heat recovery and dioxin destruction.

[0009] A method for treating high-salt and high-TOC wastewater, the method adopts a vertical-oxidation integrated furnace, and comprises the following steps:

[0010] 1) After being atomized, the high-salt and high-TOC wastewater to be treated enters the vertical furnace of the vertical-oxidation integrated furnace. In the vertical furnace, the water in the high-salt and high-organic wastewater is evaporated and removed, and the water enters the exhaust gas treatment system along with the flue gas. The organic matter carried in the salt is partially removed in the vertical furnace, and the solid salt falls into the high-temperature molten oxidation pool located below the vertical furnace;

[0011] 2) Flue gas enters the secondary combustion chamber of the tail gas treatment system through the flue, where dioxins are destroyed before being discharged;

[0012] 3) In the high-temperature molten oxidation tank, the solid salt is heated into a molten state, and the organic matter wrapped in the solid salt is further oxidized, and finally a product that meets the requirements of chlor-alkali use is obtained.

[0013] Preferably according to the present invention, the vertical-oxidation integrated furnace includes a vertical furnace and a high-temperature molten oxidation pool, the upper end of the vertical furnace is provided with a feed port, and the lower end is provided with a discharge port, the discharge port of the vertical furnace coincides with the feed port of the high-temperature molten oxidation pool, an atomizing nozzle and a heat supply device are provided at the upper end of the vertical furnace, the heat supply device includes a connected fuel input pipeline and a compressed air pipeline, the high-temperature molten oxidation pool is a sealed structure, the feed port is provided at the top of one side to coincide with the discharge port of the vertical furnace, and a product discharge port is provided at the end of the high-temperature molten oxidation pool.

[0014] Preferably, according to the present invention, in step 1), the residence time of the atomized high-salt and high-TOC wastewater to be treated in the vertical furnace is 5-30s, and the operating temperature of the vertical furnace is 600-800°C.

[0015] Preferably according to the present invention, in step 2), the residence time of the flue gas in the secondary combustion chamber is greater than or equal to 2S, and the temperature of the secondary combustion chamber is greater than or equal to 1100°C.

[0016] Further preferably, in step 2), the residence time of the flue gas in the secondary combustion chamber is 3-10S, and the temperature of the secondary combustion chamber is 1100-1500°C.

[0017] Preferably according to the present invention, in step 3), the operating temperature of the high temperature molten oxidation tank is 850-950°C.

[0018] Further preferably, in step 3), the operating temperature of the high temperature molten oxidation tank is 900°C.

[0019] Preferably according to the present invention, in step 3), the residence time of the solid salt in the high temperature molten oxidation tank is 5-40s.

[0020] The technical solution of the present invention combines a vertical furnace and a high-temperature molten oxidation furnace, and couples solid-liquid separation and high-temperature molten oxidation to remove organic matter into one device, which can effectively utilize heat and reduce processing energy consumption, while saving investment and floor space.

[0021] By adopting the above technology, the beneficial effects of the present invention are:

[0022] 1. Currently, the treatment of high-salt and high-organic wastewater basically produces mother liquor. The method of the present invention combines high-temperature melting oxidation technology to directly treat high-salt wastewater, especially high-organic and high-salt wastewater, without producing mother liquor, with low cost and simple operation.

[0023] 2. The method for treating high-salt and high-TOC wastewater of the present invention couples a vertical furnace and a high-temperature melting oxidation furnace, which not only realizes solid-liquid separation, but also solves the problem of solid salt encapsulating organic matter and incomplete removal of organic matter.

[0024] 3. The method for treating high-salt and high-TOC wastewater of the present invention can treat high-salt and high-organic waste liquid, solid salt, or a mixture of high-salt and high-organic waste liquid and solid salt. It is also applicable to high-salt and low-organic waste liquid, and has a wide range of applications.

[0025] 4. The method for treating high-salt and high-TOC wastewater of the present invention can directly meet the requirements for the use of chlorine and alkali according to the existing solidification process, and can realize the recycling of resources.

[0026] 5. The method for treating high-salt and high-TOC wastewater of the present invention can completely remove organic matter without the need for recrystallization.

[0027] 6. The method for treating high-salt and high-TOC wastewater of the present invention has a compact device and occupies a small area. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the structure of a vertical-oxidation integrated furnace;

[0029] In the figure, 1 is an atomizing nozzle, 2 is a compressed air pipeline, 3 is a fuel input pipeline, 4 is a high-temperature molten oxidation tank, 5 is a product discharge port, and 6 is a vertical furnace. Specific implementation methods

[0031] The preferred embodiments of the present invention are described below. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0032] The vertical-oxidation integrated furnace in the embodiment includes a vertical furnace 6 and a high-temperature molten oxidation pool. The upper end of the vertical furnace is provided with a feed port, and the lower end is provided with a discharge port. The discharge port of the vertical furnace coincides with the feed port of the high-temperature molten oxidation pool. An atomizing nozzle 1 and a heat supply device are provided at the upper end of the vertical furnace. The heat supply device includes a connected fuel input pipeline 3 and a compressed air pipeline 2. The high-temperature molten oxidation pool 4 is a sealed structure. The feed port is arranged at the top of one side to coincide with the discharge port of the vertical furnace. A product discharge port 5 is provided at the end of the high-temperature molten oxidation pool. Example 1

[0033] A method for treating high-salt and high-TOC wastewater, the method adopts a vertical-oxidation integrated furnace, and comprises the following steps:

[0034] 1) After being atomized, the high-salt and high-TOC wastewater to be treated enters the vertical furnace of the vertical-oxidation integrated furnace and stays there for 10 seconds. The operating temperature of the vertical furnace is 720°C. In the vertical furnace, the water in the high-salt and high-organic wastewater is evaporated and removed, and the water enters the exhaust gas treatment system along with the flue gas. The organic matter carried in the salt is partially removed in the vertical furnace, and the solid salt falls into the high-temperature molten oxidation pool located below the vertical furnace;

[0035] 2) Flue gas enters the secondary combustion chamber of the exhaust gas treatment system through the flue, where dioxins are destroyed before being discharged; the residence time of flue gas in the secondary combustion chamber is 5S, and the temperature of the secondary combustion chamber is 1200℃

[0036] 3) In the high-temperature molten oxidation tank, the solid salt is heated into a molten state, and the organic matter wrapped in the solid salt is further oxidized, and finally a product that meets the requirements of chlor-alkali use is obtained. The operating temperature of the high-temperature molten oxidation tank is 900°C, and the residence time of the solid salt in the high-temperature molten oxidation tank is 20s.

[0037] Application Experiment Example 1

[0038] A method for treating high-salt and high-TOC wastewater, the steps are as follows:

[0039] The water quality of high-salt and high-organic matter wastewater is: COD141042mg / L, salt content 16%, pH9.12. The main pollutants are pesticide products and their intermediates, containing tar substances.

[0040] High-salt and high-organic wastewater is transported into the gasifier 6 through the atomizing nozzle 1. The combustion-supporting materials or waste solvents input from the fuel input pipeline 3 are burned under the action of the compressed air input from the compressed air pipeline 2, providing heat to the gasifier 6, so that the high-salt and high-organic wastewater can achieve solid-liquid separation in the gasifier. The solid salt falls into the high-temperature melting oxidation furnace 4 and is further heated and converted into a high-temperature molten state. While melting, the organic matter is further completely removed and flows out of the system through the discharge port 5 and enters the discharge system. The discharge port of the solid material of the gasifier 6 and the feed port of the high-temperature melting oxidation furnace 4 are overlapped, that is, the solid material falls directly from the gasifier into the high-temperature melting oxidation furnace without the need for other intermediate transmission equipment.

[0041] The operating temperature of the gasifier 6 is 720°C, and the operating temperature of the high-temperature melting oxidation furnace is 900°C. The obtained product indicators are shown in Table 1 below:

[0042] Table 1

[0043] project TOC mg / kg Sodium chloride% Moisture% Water insoluble content% color Product Salt 3.26 99.67 0.57 0.05 Pure White

[0044] Application Experiment Example 2

[0045] A method for treating high-salt and high-TOC wastewater, the steps are as follows:

[0046] The water quality of high-salt and high-organic wastewater is as follows: COD17321mg / L, salt content 15%, pH8.98, and the main pollutants are cyanoacetic acid products and their intermediates.

[0047] High-salt and high-organic wastewater is transported into the gasifier 6 through the atomizing nozzle 1. The combustion-supporting materials or waste solvents input from the fuel input pipeline 3 are burned under the action of the compressed air input from the compressed air pipeline 2, providing heat to the gasifier 6, so that the high-salt and high-organic wastewater can achieve solid-liquid separation in the gasifier. The solid salt falls into the high-temperature melting oxidation furnace 4 and is further heated and converted into a high-temperature molten state. While melting, the organic matter is further completely removed and flows out of the system through the discharge port 5 and enters the discharge system. The discharge port of the solid material of the gasifier 6 and the feed port of the high-temperature melting oxidation furnace 4 are overlapped, that is, the solid material falls directly from the gasifier into the high-temperature melting oxidation furnace without the need for other intermediate transmission equipment.

[0048] The operating temperature of the gasifier 6 is 800°C, and the operating temperature of the high-temperature melting oxidation furnace is 850°C. The obtained product indicators are shown in Table 2 below:

[0049] Table 2

[0050] project TOC mg / kg Sodium chloride% Moisture% Water insoluble content% color Product Salt 1.17 99.76 0.47 0.055 Pure White

[0051] Unless otherwise specified, all percentages used in the present invention are mass percentages, and all ratios are volume ratios.

[0052] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for treating high-salt and high-TOC wastewater, the method comprising: atomization, organic removal, organic oxidation removal, heat recovery and dioxin destruction.

2. A method for treating high-salt and high-TOC wastewater, which adopts a vertical-oxidation integrated furnace and comprises the following steps: 1) After being atomized, the high-salt and high-TOC wastewater to be treated enters the vertical furnace of the vertical-oxidation integrated furnace. In the vertical furnace, the water in the high-salt and high-organic wastewater is evaporated and removed, and the water enters the exhaust gas treatment system along with the flue gas. The organic matter carried in the salt is partially removed in the vertical furnace, and the solid salt falls into the high-temperature molten oxidation pool located below the vertical furnace; 2) Flue gas enters the secondary combustion chamber of the tail gas treatment system through the flue, where dioxins are destroyed before being discharged; 3) In the high-temperature molten oxidation tank, the solid salt is heated into a molten state, and the organic matter wrapped in the solid salt is further oxidized, and finally a product that meets the requirements of chlor-alkali use is obtained.

3. The processing method according to claim 2, characterized in that: The vertical-oxidation integrated furnace includes a vertical furnace and a high-temperature molten oxidation pool. The upper end of the vertical furnace is provided with a feed port, and the lower end is provided with a discharge port. The discharge port of the vertical furnace coincides with the feed port of the high-temperature molten oxidation pool. An atomizing nozzle and a heat supply device are provided at the upper end of the vertical furnace. The heat supply device includes a connected fuel input pipeline and a compressed air pipeline. The high-temperature molten oxidation pool is a sealed structure. The feed port is arranged at the top of one side to coincide with the discharge port of the vertical furnace. A product discharge port is provided at the end of the high-temperature molten oxidation pool.

4. The processing method according to claim 2, characterized in that: In step 1), the residence time of the atomized high-salt and high-TOC wastewater to be treated in the vertical furnace is 5-30s, and the operating temperature of the vertical furnace is 600-800°C.

5. The processing method according to claim 2, characterized in that: In step 2), the residence time of the flue gas in the secondary combustion chamber is greater than or equal to 2S, and the temperature of the secondary combustion chamber is greater than or equal to 1100°C.

6. The processing method according to claim 2, characterized in that: In step 2), the residence time of the flue gas in the secondary combustion chamber is 3-10S, and the temperature of the secondary combustion chamber is 1100-1500°C.

7. The processing method according to claim 2, characterized in that: In step 3), the operating temperature of the high temperature molten oxidation tank is 850-950°C.

8. The processing method according to claim 2, characterized in that: In step 3), the operating temperature of the high temperature molten oxidation tank is 900°C.

9. The processing method according to claim 2, characterized in that: In step 3), the residence time of the solid salt in the high-temperature molten oxidation tank is 5-40s.

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