Treatment system for high-COD (Chemical Oxygen Demand) and high-chroma wastewater containing nitrobenzoic acid

Abstract

The utility model discloses a treatment system for high-COD (Chemical Oxygen Demand) and high-chroma wastewater containing nitrobenzoic acid. The treatment system comprises a first centrifugal machine, a liquid ammonia storage tank, a liquid ammonia neutralizing tower, an oxidizing pot, a filter press, a treatment water tank, a distillation kettle and a second centrifugal machine. The method has the advantages that after the mother liquor is neutralized and diluted through liquid ammonia, the PH is adjusted to 4-4.5, reagents such as hydrogen peroxide and ferrous sulfate are added into the mother liquor, strong-oxygen hydroxyl free radicals are formed in a slightly acidic environment, organic matter and nitro in water are decomposed into micromolecular substances, then calcium oxide and a flocculating agent are added for flocculation, and then the micromolecular substances are separated through a filter press; the separated ammonium sulfate is better in appearance quality and has higher economic benefits; and the filtrate discharged by the filter press is evaporated and concentrated by the distillation kettle to obtain condensate which is used as bottom water of the dilution kettle, so that the recycling of water resources is realized.

Description

Technical Field

[0001] The utility model relates to the technical field of nitrobenzoic acid production, in particular to a treatment system for high-COD and high-chroma wastewater containing nitrobenzoic acid. Background Art

[0002] 3,5-Dinitrobenzoic acid is obtained by nitration of benzoic acid. Specifically, sulfuric acid is added to a dry reaction pot, benzoic acid is added under stirring, heated to 60°C, fuming nitric acid is added dropwise, and the addition is completed below 85°C; the reaction is carried out at 80-85°C for 1h, at 100°C for 0.5-1h, and then the temperature is raised to 135°C for 2h; the thick nitrobenzoic acid obtained by placing it overnight is metered in a metering tank and sent to a dilution kettle, diluted with dilution water, and then solid-liquid separation is performed using a first centrifuge. After solid-liquid separation, 3,5-Dinitrobenzoic acid and diluted acidic wastewater are obtained. The diluted acidic wastewater generated in the production process of 3,5-Dinitrobenzoic acid is dark yellow, with a chromaticity of up to 40,000-45,000 times, COD exceeding 20,000 mg / L, ammonia nitrogen greater than 300 mg / L, acidity of 25-28%, and contains no less than 4% nitric acid. The main organic components are benzene compounds containing nitro groups. Every ton of 3,5-dinitrobenzoic acid produced generates about 25 tons of acidic wastewater. The traditional wastewater treatment method is to neutralize the wastewater with ammonia water and then centrifuge it through a multi-effect evaporator. There is no other treatment method after centrifugation. The centrifuged mother liquor has a high content of nitro organic matter, and the nitric acid contained in the wastewater forms dangerous substances such as nitrates after neutralization, which poses certain safety risks. The remaining centrifuged mother liquor and condensed water cannot be reused to achieve standard discharge, which has a severe impact on the environment. Utility Model Content

[0003] The utility model aims to provide a treatment system for high-COD and high-chroma wastewater containing nitrobenzoic acid.

[0004] The utility model is implemented by the following technical scheme: a treatment system for high-COD and high-chroma wastewater containing nitrobenzoic acid, which comprises a liquid ammonia storage tank, a liquid ammonia neutralization tower, an oxidation pot, a filter press, a treated water tank, a distillation kettle, and a second centrifuge, wherein a wastewater feed pipe is connected to the inlet of the liquid ammonia neutralization tower, and the outlet of the liquid ammonia storage tank is connected to the liquid ammonia inlet of the liquid ammonia neutralization tower; the outlet of the liquid ammonia neutralization tower is connected to the inlet of the oxidation pot, the outlet of the oxidation pot is connected to the inlet of the filter press, the filtrate outlet of the filter press is connected to the inlet of the treated water tank, the outlet of the treated water tank is connected to the inlet of the distillation kettle, the discharge port of the distillation kettle is connected to the inlet of the second centrifuge, and the filtrate outlet of the second centrifuge is connected to the inlet of the distillation kettle.

[0005] Furthermore, the exhaust port of the distillation kettle is communicated with the inlet of the condenser, the outlet of the condenser is communicated with the inlet of the recycling water tank, and the outlet of the recycling water tank is communicated with the process water inlet of the dilution kettle.

[0006] Furthermore, it also includes a hydrogen peroxide dosing tank connected to the oxidation pot, and the oxidation pot is also provided with a calcium oxide dosing port, a ferrous sulfate dosing port and a flocculant dosing port.

[0007] Furthermore, a mother liquid buffer tank is provided between the filtrate outlet of the second centrifuge and the inlet of the distillation kettle, the filtrate outlet of the second centrifuge is connected to the inlet of the mother liquid buffer tank, and the outlet of the mother liquid buffer tank is connected to the inlet of the distillation kettle.

[0008] The utility model has the advantages that the high COD and high chromaticity wastewater produced by the dilution of nitrobenzoic acid is adjusted to pH 4-4.5 after the mother liquor is diluted and neutralized with liquid ammonia, and strong oxygen hydroxyl radicals are formed in a slightly acidic environment by adding reagents such as hydrogen peroxide and ferrous sulfate to the mother liquor, and the organic matter and nitro in the water are decomposed into small molecular substances, and then calcium oxide and flocculants are added to flocculate them, and then they are separated by a filter press; the separated ammonium sulfate has better appearance quality and higher economic benefits; the condensate discharged from the filter press is used as the bottom water of the dilution kettle after the filtrate is evaporated and concentrated by a distillation kettle, realizing the recycling of water resources. The method greatly reduces the organic matter in the diluted wastewater, reduces the load of subsequent decolorization treatment, and removes the dangerous substances contained in the wastewater, thereby improving the production safety factor to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a schematic diagram of the overall structure of the utility model.

[0010] Metering tank 1, dilution kettle 2, first centrifuge 3, liquid ammonia storage tank 4, liquid ammonia neutralization tower 5, oxidation pot 6, filter press 7, treated water tank 8, distillation kettle 9, second centrifuge 10, mother liquor buffer tank 11, recycled water tank 12, hydrogen peroxide dosing tank 13, calcium oxide dosing port 14, ferrous sulfate dosing port 15, flocculant dosing port 16, condenser 17. DETAILED DESCRIPTION

[0011] In the description of the present invention, it should be noted that if the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, if the terms "first", "second", "third" appear, they are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0012] like Figure 1 As shown, a treatment system for high COD and high chroma wastewater containing nitrobenzoic acid comprises a liquid ammonia storage tank 4, a liquid ammonia neutralization tower 5, an oxidation pot 6, a filter press 7, a treated water tank 8, a distillation kettle 9, and a second centrifuge 10.

[0013] The outlet of the metering tank 1 is connected to the inlet of the dilution kettle 2, the outlet of the dilution kettle 2 is connected to the inlet of the first centrifuge 3, the filtrate outlet of the first centrifuge 3 is connected to the inlet of the liquid ammonia neutralization tower 5 through the wastewater feed pipe, and the outlet of the liquid ammonia storage tank 4 is connected to the liquid ammonia inlet of the liquid ammonia neutralization tower 5; the outlet of the liquid ammonia neutralization tower 5 is connected to the inlet of the oxidation pot 6, the outlet of the oxidation pot 6 is connected to the inlet of the filter press 7, the filtrate outlet of the filter press 7 is connected to the inlet of the treated water tank 8, the outlet of the treated water tank 8 is connected to the inlet of the distillation kettle 9, and the discharge port of the distillation kettle 9 is connected to the inlet of the second centrifuge 10; a mother liquor buffer tank 11 is arranged between the filtrate outlet of the second centrifuge 10 and the inlet of the distillation kettle 9, the filtrate outlet of the second centrifuge 10 is connected to the inlet of the mother liquor buffer tank 11, and the outlet of the mother liquor buffer tank 11 is connected to the inlet of the distillation kettle 9.

[0014] The exhaust port of the distillation kettle 9 is communicated with the inlet of the condenser 17 , the outlet of the condenser 17 is communicated with the inlet of the recycling water tank 12 , and the outlet of the recycling water tank 12 is communicated with the process water inlet of the dilution kettle 2 .

[0015] It also includes a hydrogen peroxide dosing tank 13, a calcium oxide dosing port 14, a ferrous sulfate dosing port 15 and a flocculant dosing port 16 which are connected to the dosing port of the oxidation pot 6.

[0016] Working process:

[0017] (1) Process water and nitrobenzoic acid slurry in metering tank 1 enter dilution kettle 2 to react and generate diluted mother liquor, which is then sent to first centrifuge 3 for solid-liquid separation, and the separated diluted liquid enters liquid ammonia neutralization tower 5;

[0018] (2) After the liquid ammonia in the liquid ammonia storage tank 4 enters the liquid ammonia neutralization tower 5, it flows from bottom to top, and the diluted mother liquor enters the liquid ammonia neutralization tower 5 and flows from top to bottom, forming a convection reaction. After the bottom circulation pump of the liquid ammonia neutralization tower 5 controls the pH to be within the acceptable range of 4-4.5, the neutralized liquid discharged from the liquid ammonia neutralization tower 5 enters the oxidation pot 6;

[0019] (3) First, add hydrogen peroxide, ferrous sulfate and other reagents to the oxidation pot 6 to form strong oxygen hydroxyl free radicals in a slightly acidic environment, decompose the organic matter and nitro in the neutralization solution into small molecules, and then add calcium oxide and flocculant to flocculate them;

[0020] (4) The treated liquid after the reaction in the oxidation pot 6 is sent to the filter press 7 for solid-liquid separation. The separated solid is calcium sulfide, and the treated liquid is sent to the treated water tank 8 for temporary storage;

[0021] (5) The treated liquid temporarily stored in the treated water tank 8 is sent to the distillation kettle 9 for steam heating, evaporation and concentration to a certain volume, and then added to the second centrifuge 10 for solid-liquid separation. The separated solid is ammonium sulfate, which can be packaged and sold; the separated centrifuged mother liquor is sent back to the distillation kettle 9 for recycling treatment. The non-condensable gas discharged from the distillation kettle 9 enters the condenser 17 for condensation and then enters the reuse water tank 12. The condensed water is collected in the reuse water tank 12 and the gas is emptied; the condensed water collected in the reuse water tank 12 is then sent back to the dilution kettle 2 for reuse.

[0022] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model, rather than to limit it. Although the utility model has been described in detail with reference to the aforementioned embodiments, ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solution of the embodiments of the utility model.

Claims

1. A treatment system for high COD and high chroma wastewater containing nitrobenzoic acid, characterized in that: It also includes a liquid ammonia storage tank, a liquid ammonia neutralization tower, an oxidation pot, a filter press, a treated water tank, a distillation kettle, and a second centrifuge. The wastewater feed pipe is connected to the inlet of the liquid ammonia neutralization tower, and the outlet of the liquid ammonia storage tank is connected to the liquid ammonia inlet of the liquid ammonia neutralization tower; the outlet of the liquid ammonia neutralization tower is connected to the inlet of the oxidation pot, the outlet of the oxidation pot is connected to the inlet of the filter press, the filtrate outlet of the filter press is connected to the inlet of the treated water tank, the outlet of the treated water tank is connected to the inlet of the distillation kettle, the discharge port of the distillation kettle is connected to the inlet of the second centrifuge, and the filtrate outlet of the second centrifuge is connected to the inlet of the distillation kettle.

2. A treatment system for high COD and high chroma wastewater containing nitrobenzoic acid according to claim 1, characterized in that: The exhaust port of the distillation kettle is communicated with the inlet of the condenser, the outlet of the condenser is communicated with the inlet of the recycling water tank, and the outlet of the recycling water tank is communicated with the process water inlet of the dilution kettle.

3. A treatment system for high COD and high chroma wastewater containing nitrobenzoic acid according to claim 1, characterized in that: It also includes a hydrogen peroxide dosing tank connected to the oxidation pot, and the oxidation pot is also provided with a calcium oxide dosing port, a ferrous sulfate dosing port and a flocculant dosing port.

4. A treatment system for high COD and high chroma wastewater containing nitrobenzoic acid according to claim 1, characterized in that: A mother liquid buffer tank is provided between the filtrate outlet of the second centrifuge and the inlet of the distillation kettle, the filtrate outlet of the second centrifuge is connected to the inlet of the mother liquid buffer tank, and the outlet of the mother liquid buffer tank is connected to the inlet of the distillation kettle.

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