Treatment system for methane chloride cleaning wastewater and waste alkali of incineration system

Abstract

The utility model relates to the technical field of three-waste treatment, in particular to a treatment system for methane chloride cleaning wastewater and waste alkali of an incineration system, which comprises a dechlorination treatment unit, a neutralization coagulation unit and a triple-effect evaporation device which are communicated in sequence, and the triple-effect evaporation device is respectively communicated with a biochemical unit and a vacuum device. The dechlorination treatment unit comprises a dechlorination tank, a first pH regulator storage tank, a catalyst storage tank and a reducing agent storage tank, the dechlorination tank is respectively communicated with the first pH regulator storage tank, the catalyst storage tank and the reducing agent storage tank, the neutralization and coagulation unit comprises a neutralization tank, a waste alkali storage tank and a coagulant storage tank, the neutralization tank is respectively communicated with the waste alkali storage tank and the coagulant storage tank, and the first pH regulator storage tank is communicated with the neutralization tank. The biochemical unit comprises an adjusting tank, a raw water tank, an anaerobic tank, an aerobic tank, a secondary sedimentation tank, an intermediate reaction tank, a tertiary sedimentation tank, a sand filter tank and a carbon filter tank which are communicated in sequence; the dechlorination tank is respectively communicated with an external wastewater pipeline and the neutralization tank, and the neutralization tank is communicated with the triple-effect evaporation device. And the wastewater and the waste alkali of the incineration system are well treated at the same time.

Description

Technical Field

[0001] This utility model relates to the field of waste treatment technology, specifically a treatment system for methane chloride cleaning wastewater and incineration system waste alkali. Background Technology

[0002] Chlorinated methane, also known as chloromethane (CMS), is a general term encompassing four products: monochloromethane, dichloromethane, trichloromethane (chloroform), and carbon tetrachloride. It is an important solvent and chemical raw material. Due to blockages caused by long-term operation of production equipment, large amounts of cleaning fluid containing impurities such as salt, acid, and carbon black are discharged into the water treatment system during the cleaning process. This cleaning fluid contains significant amounts of chlorinated methane, making it extremely difficult to treat.

[0003] Methane chloride cleaning wastewater is not only complex in composition, but also highly hazardous, specifically manifested in the following ways:

[0004] (1) Microorganisms cannot decompose the acid-base mixture in the methane chloride cleaning wastewater, and these acid-base mixtures are highly toxic, so they can easily reduce the activity of microorganisms.

[0005] (2) The accumulation of non-degradable harmful substances in cleaning wastewater in the natural environment over a long period of time will be detrimental to the ecological balance and will cause serious consequences.

[0006] (3) Methane chloride contains carbon trichloride and carbon tetrachloride. When mixed in wastewater, it will produce harmful substances that endanger human health. Most of these are incurable diseases. In addition, carbon tetrachloride is not only highly toxic, but also a major substance that destroys the ozone layer, causing great harm.

[0007] Existing technologies, such as Chinese patent document CN 204529540 U (application number 201520198254.9), disclose a methane chloride organic wastewater treatment system, which decomposes organic compounds such as trichloro and carbon tetrachloride by adding hydrogen peroxide and ferrous salts to the wastewater under acidic conditions; another example is Chinese patent document CN 113307423 A (application number 202110862774.5), which discloses a system for treating organic chlorine wastewater using a coupling technology of electro-dechlorination and chemical dechlorination, achieving better dechlorination through the combined use of electro-dechlorination and chemical dechlorination technologies. It can be seen that existing technologies for treating organic chlorine wastewater only focus on the removal of organic chlorine.

[0008] The waste alkali produced by the incineration system contains various organic wastes, such as chloromethane, trichloroethylene, hexachloroethane, tetrachloroethylene, and carbon black. Most of these substances are toxic, corrosive, or flammable and explosive, significantly increasing the difficulty of waste alkali treatment. Chlorinated hydrocarbons such as trichloroethylene and tetrachloroethylene are not only volatile but may also pose health risks. While hexachloroethane is relatively chemically stable, it can decompose under certain conditions, producing toxic and harmful byproducts. Carbon tetrachloride is an even more serious pollutant, causing long-term pollution to the atmosphere, water bodies, and soil.

[0009] In addition, carbon black substances in waste alkali may affect its color and turbidity, further increasing the difficulty of treatment. Utility Model Content

[0010] The purpose of this invention is to overcome the shortcomings of the prior art and provide a treatment system for methane chloride cleaning wastewater and incineration system waste alkali. This system can not only achieve effective dechlorination, but also effectively ensure the removal of other organic matter, reduce the concentration of harmful substances, improve treatment efficiency, and realize the resource utilization of wastewater through triple-effect evaporation and biochemical treatment.

[0011] To achieve the above-mentioned technical effects, the present invention adopts the following technical solution:

[0012] A treatment system for polychlorinated methane (PCB) cleaning wastewater and incineration system waste alkali includes a dechlorination unit, a neutralization and coagulation unit, and a triple-effect evaporator connected in sequence. The triple-effect evaporator is also connected to a biochemical unit and a vacuum unit.

[0013] The dechlorination unit includes a dechlorination tank, a first pH adjuster storage tank, a catalyst storage tank, and a reducing agent storage tank. The dechlorination tank is connected to the first pH adjuster storage tank, the catalyst storage tank, and the reducing agent storage tank, respectively.

[0014] The neutralization and coagulation unit includes a neutralization tank, a waste alkali storage tank, and a coagulant storage tank. The neutralization tank is connected to both the waste alkali storage tank and the coagulant storage tank.

[0015] The biochemical unit includes, in sequence, an equalization tank, a raw water tank, an anaerobic tank, an aerobic tank, a secondary sedimentation tank, an intermediate reaction tank, a tertiary sedimentation tank, a sand filter, and a carbon filter.

[0016] The dechlorination tank is connected to the external wastewater pipeline and the neutralization tank, which is connected to the triple-effect evaporator.

[0017] Preferably, the dechlorination unit includes at least two dechlorination tanks connected in series, each of which is connected to a catalyst storage tank and a reducing agent storage tank, respectively. More preferably, the dechlorination tank is provided with a fluorine-based corrosion-resistant layer inside.

[0018] By setting up multiple dechlorination tanks connected in series, the complete removal of organochlorine elements in the wastewater is ensured.

[0019] Preferably, the bottom of the neutralization coagulation unit is connected to a filter press, which is used to separate the sludge and colloidal substances produced by the neutralization coagulation unit from the waste sludge and the second intermediate liquid.

[0020] Preferably, the triple-effect evaporator includes a triple-effect evaporator, a first-effect evaporator, a second-effect evaporator, and a condenser connected in sequence; the vacuum device includes a vacuum pump and a vacuum filter, the vacuum pump being connected to each evaporator (including the first-effect evaporator, the second-effect evaporator, and the triple-effect evaporator) and the condenser in the triple-effect evaporator, and the vacuum pump being used to create a negative pressure state inside the triple-effect evaporator; the vacuum filter is connected to the discharge port of the second-effect evaporator in the triple-effect evaporator.

[0021] Preferably, the condenser in the triple-effect evaporator is connected to the conditioning tank in the biochemical unit. More preferably, a second pH adjusting agent storage tank is connected to the conditioning tank, and a pH sensor is installed inside the conditioning tank. The conditioning tank is used to adjust the pH of the liquid inside to 8-9.

[0022] Preferably, the liquid outlet of the vacuum filter is connected to a triple-effect evaporator, and the solid outlet of the vacuum filter is connected to a drying device.

[0023] More preferably, the gas outlet of the drying equipment is connected to the biological system via an intermediate condenser. The condensate generated from the gas produced by the drying equipment after condensation in the intermediate condenser directly enters the biological system. This intermediate condenser needs to be used separately from the condenser of the triple-effect evaporator to avoid mutual constraints caused by pressure, operating temperature, and operating time. Separating the two condensers allows for greater production flexibility.

[0024] The beneficial effects of this utility model are as follows:

[0025] The device for treating polychlorinated methane cleaning wastewater and incineration system waste alkali provided by this utility model first dechlorinates the polychlorinated methane cleaning wastewater, taking into account both organic and inorganic chlorine. Then, after triple-effect evaporation and biochemical treatment, the wastewater can be discharged and utilized. At the same time, the treatment method also achieves the joint treatment of waste alkali, which greatly improves the treatment efficiency. Attached Figure Description

[0026] Figure 1 This is the treatment system for polychlorinated methane cleaning wastewater and incineration system waste alkali provided in Example 1;

[0027] Figure 2 This is a schematic diagram of the dechlorination treatment unit in Example 1;

[0028] Figure 3This is a schematic diagram of the structure of the neutralization coagulation unit and the filter press in Example 1;

[0029] Figure 4 This is a schematic diagram of the triple-effect evaporator and vacuum device in Example 1;

[0030] Figure 5 This is a schematic diagram of the biochemical unit in Example 1;

[0031] The system comprises: 1. Dechlorination unit; 2. Neutralization and coagulation unit; 3. Triple-effect evaporator; 4. Biochemical unit; 5. Vacuum device; 101. First dechlorination tank; 102. Second dechlorination tank; 103. First pH adjuster storage tank; 104. Catalyst storage tank; 105. Reducing agent storage tank; 106. Circulation pump; 201. Neutralization tank; 202. Waste alkali storage tank; 203. Coagulant storage tank; 204. Filter press; 301. First-effect evaporator; 302. Second-effect evaporator; 303. Triple-effect evaporator; 304. Condenser; 401. Equalization tank; 402. Raw water tank; 403. Anaerobic tank; 404. Aerobic tank; 405. Secondary sedimentation tank; 406. Intermediate reaction tank; 407. Tertiary sedimentation tank; 408. Sand filter tank; 409. Carbon filter tank; 501. Vacuum pump; 502. Vacuum filter. Detailed Implementation

[0032] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0033] The apparatus and materials used in each embodiment and experimental example are all commonly used in the art, and their specific sources will not be repeated here.

[0034] Example 1

[0035] A system for treating polychlorinated methane cleaning wastewater and incineration system waste alkali, such as... Figure 1 As shown, the system includes a dechlorination unit 1, a neutralization and coagulation unit 2, and a triple-effect evaporator 3 connected in sequence. The triple-effect evaporator 3 is also connected to a biochemical unit 4 and a vacuum unit 5.

[0036] Dechlorination treatment unit 1 includes a dechlorination tank, a first pH adjuster storage tank 103, a catalyst storage tank 104, and a reducing agent storage tank 105. The dechlorination tank is connected to the first pH adjuster storage tank, the catalyst storage tank 104, and the reducing agent storage tank 105, respectively.

[0037] Neutralization and coagulation unit 2 includes a neutralization tank 201, a waste alkali storage tank 202, and a coagulant storage tank 203. The neutralization tank 201 is connected to both the waste alkali storage tank 202 and the coagulant storage tank 203.

[0038] The biochemical unit 4 includes an equalization tank 401, a raw water tank 402, an anaerobic tank 403, an aerobic tank 404, a secondary sedimentation tank 405, an intermediate reaction tank 406, a tertiary sedimentation tank 407, a sand filter tank 408, and a carbon filter tank 409 connected in sequence.

[0039] The dechlorination tank is connected to the external wastewater pipeline and the neutralization tank 201, and the neutralization tank 201 is connected to the triple-effect evaporator 3.

[0040] The dechlorination treatment unit 1 includes at least two dechlorination tanks connected in series, each of which is connected to the catalyst storage tank 104 and the reducing agent storage tank 105, respectively. The interior of the dechlorination tank is lined with a fluorine-based corrosion-resistant layer.

[0041] By setting up multiple dechlorination tanks connected in series, the complete removal of organochlorine elements in the wastewater is ensured.

[0042] The bottom of the neutralization coagulation unit 2 is connected to the filter press 204, which is used to separate the waste sludge from the sludge and colloidal substances produced by the neutralization coagulation unit 2 from the second intermediate liquid.

[0043] The triple-effect evaporator 3 includes a triple-effect evaporator 303, a first-effect evaporator 301, a second-effect evaporator 302, and a condenser 304 connected in sequence; the vacuum device 5 includes a vacuum pump 501 and a vacuum filter 502. The vacuum pump 501 is connected to each evaporator (including the first-effect evaporator 301, the second-effect evaporator 302, and the triple-effect evaporator 303) and the condenser 304 in the triple-effect evaporator 3. The vacuum pump 501 is used to create a negative pressure inside the triple-effect evaporator 3; the vacuum filter 502 is connected to the discharge port of the second-effect evaporator 302 in the triple-effect evaporator 3.

[0044] The condenser 304 in the triple-effect evaporator 3 is connected to the conditioning tank 401 in the biochemical unit 4. The conditioning tank 401 is connected to a second pH conditioning agent storage tank. The conditioning tank 401 is equipped with a pH sensor and is used to adjust the pH of the liquid inside to 8-9.

[0045] The liquid outlet of the vacuum filter 502 is connected to the triple-effect evaporator 303, and the solid outlet of the vacuum filter 502 is connected to the drying equipment.

[0046] The gas outlet of the drying equipment is connected to the biochemical system via an intermediate condenser 304. The condensate produced after the gas generated by the drying equipment is condensed by the intermediate condenser 304 directly enters the biochemical system. The intermediate condenser 304 here needs to be used separately from the condenser 304 of the triple-effect evaporator to avoid mutual constraints caused by pressure, operating temperature, and operating time. Separating the two condensers 304 can make production more flexible.

[0047] In this embodiment, the dechlorination tank includes a first dechlorination tank 101 and a second dechlorination tank 102 connected in series. Both the first dechlorination tank 101 and the second dechlorination tank 102 are connected to a circulation pump 106. The inlet of the circulation pump 106 is connected to the bottom of the dechlorination tank, and the outlet of the circulation pump 106 is connected to the top of the dechlorination tank.

[0048] Example 2

[0049] A method for treating polychlorinated methane cleaning wastewater and incineration system waste alkali, using the treatment system provided in Example 1, comprises the following steps:

[0050] S1. Metal-catalyzed reduction dechlorination

[0051] A reducing agent and a catalyst solution were added to the methane chloride washing wastewater. The reducing agent was cast iron powder and the catalyst was sodium sulfate. After dechlorination, the first intermediate liquid was obtained.

[0052] S2. Neutralization Coagulation

[0053] Add waste alkali from the incineration system and coagulant to the first intermediate liquid obtained in step S1, adjust the pH to 10-12, remove suspended solids and colloidal substances, and obtain the second intermediate liquid.

[0054] S3. Pass the second intermediate liquid obtained in step S2 into a triple-effect evaporator.

[0055] The condensate produced by the triple-effect evaporator is fed into the biochemical unit, where it is treated before being discharged.

[0056] The solute produced in the triple-effect evaporator is vacuum filtered, and the wastewater obtained from the filtration is returned to the triple-effect evaporator for further processing. The solute with a lower water content obtained after filtration is dried, and the dried solid powder is discharged after being rendered harmless.

[0057] In step S1, the cast iron powder has a particle size of 15 mesh and contains a small amount of carbon, trace amounts of copper and nickel; the sodium sulfate is industrial grade and does not contain organic chlorides.

[0058] In step S1, the catalyst concentration in the catalyst solution is 5.5 wt%, the volume ratio of methane chloride washing wastewater to catalyst solution is 20:1, and the cast iron powder content is 1 m³ / s. 3 Use 1.5 kg of wastewater for cleaning.

[0059] The feed ratio of the first intermediate liquid, waste alkali from the incineration system, and coagulant is 1:3:0.014. The coagulant consists of equal volumes of polyaluminum chloride (PAC) solution and polyacrylamide (PAM) solution, wherein the concentration of PAC in the PAC solution is 2.5wt% and the concentration of PAM in the PAM solution is 0.2wt%.

[0060] In step S2, the specific operation of the filter press is to feed the sludge formed by adding waste alkali and coagulant to the first intermediate liquid and then feeding it into the plate and frame filter press. The liquid produced is the second intermediate liquid, which is fed into the subsequent treatment steps. The waste sludge produced is discharged after being treated to render it harmless.

[0061] In step S3, the biochemical unit processing procedure is as follows:

[0062] The condensate after triple-effect evaporation and desalination is first adjusted to pH 8-9 to meet the requirements of the biochemical system, and then subjected to anaerobic and aerobic treatment in sequence. After catalytic oxidation and precipitation, the supernatant is filtered and discharged.

[0063] In step S1,

[0064] Methane chloride washing wastewater contains high concentrations of organochlorides, requiring dechlorination treatment to avoid increasing the difficulty of subsequent treatment. The dechlorination treatment employs a metal catalytic reduction process, with the reaction carried out under acidic conditions. The reducing agent is 10-20 mesh cast iron powder, and the catalyst is sodium sulfate. The acidity of the washing wastewater is controlled at pH 2; if the acidity is insufficient, a prepared 5% hydrochloric acid solution is used for adjustment. The catalyst is prepared at a concentration of 5.5 wt%. Chloride ions (Cl-) in the wastewater undergo a redox reaction with iron (Fe) in the cast iron powder. This reaction typically results in the oxidation of iron (generating Fe2+ or Fe3+ ions) and the reduction of chloride ions. While chloride ions may not be the primary reduction target in methane chloride wastewater, the reaction of iron with chlorinated hydrocarbons may indirectly affect the form in which chloride ions exist. Simultaneously, iron undergoes a dechlorination reaction with organochlorine compounds in the wastewater (such as dichloro, chloroform, and carbon tetrachloride), converting organic chlorine into inorganic chlorine (such as chloride ions), while iron is oxidized.

[0065] In step S2, the dechlorinated water enters the neutralization tank. Waste alkali from the incineration system is added to the neutralization tank via a pump, controlling the pH to 10-12, and stirring is started. Simultaneously, a coagulant is added. This process generates insoluble iron salt precipitates during the dechlorination reaction; these precipitates can adsorb and remove some pollutants from the wastewater. Simultaneously, through the reducing effect of iron powder, organochlorine compounds in the wastewater may be effectively degraded or converted into low-toxicity substances. The sludge after coagulation and sedimentation is pumped into a sludge pressing tank, and then filtered through a plate and frame filter press. The effluent from the plate and frame filter press is pumped into a triple-effect evaporator raw water tank, and the filtered sludge undergoes harmless treatment. The plate and frame filter press uses a central feed and four-hole discharge system, with a closed-flow design, employing air pressure pressing and automatic unloading via a pull-plate trolley.

[0066] In step S3, the clarified water enters the triple-effect evaporation system, which uses a forced circulation system. The material is fed into the triple-effect separator under negative pressure. Once the liquid level is reached, the triple-effect circulation pump is activated for circulation. The material then enters the first effect, then the second effect, while the live steam enters the first effect. The second effect discharges the material, all controlled by a liquid level interlock. The condensate from the triple-effect evaporation enters the biochemical system.

[0067] In this embodiment, the biochemical system: wastewater after triple-effect evaporation and desalination first enters the raw water tank for conditioning, and then is pumped to the CYIC anaerobic bioreactor via a booster pump. This reactor utilizes the metabolic activity of methanogenic bacteria in an anaerobic environment to decompose and remove organic pollutants from the wastewater. The anaerobic wastewater then flows by gravity into the aerobic treatment unit (three aerobic tanks), then into the catalytic oxidation coagulation reaction sedimentation system (secondary sedimentation, reaction tank, and tertiary sedimentation), and finally into the COT ozone catalytic oxidation reaction unit. An activated carbon adsorption reactor is added after ozone oxidation. This reactor integrates chemical adsorption and biodegradation as a backup device, improving the quality of the effluent while extending the adsorption cycle of the biocarbon and increasing the utilization rate of the packing material. The water after activated carbon adsorption enters the recycled water tank, and then is pumped into the external drainage tank for discharge or other uses.

[0068] The waste salt drying unit uses a horizontal paddle dryer, which ensures that the wet material comes into full contact with the heat carrier and heated surfaces under the agitation of the paddles, thereby achieving the drying purpose. After drying, the material is cooled and packaged for harmless treatment. The heat medium is 0.8 MPa steam.

[0069] Experimental example:

[0070] The polychlorinated methane (PCB) cleaning wastewater and incineration system waste alkali were treated according to the method provided in Example 2. The contents of relevant substances in the incineration system waste alkali and PCB cleaning wastewater before and after treatment are shown in the table below.

[0071] Table 1 Alkali content in incineration system waste

[0072]

[0073]

[0074] Table 2. Substance content in polychlorinated methane cleaning wastewater

[0075]

[0076] As shown in Tables 1 and 2, all key parameters in the treated polychlorinated methane cleaning wastewater were effectively controlled, proving that the treatment method provided by this utility model is effective.

Claims

1. A system for treating waste water from a methyl chloride wash and waste caustic from an incineration system, characterized by, The dechlorination treatment unit, the neutralization and coagulation unit and the three-effect evaporation device are sequentially connected, and the three-effect evaporation device is also connected with the biochemical unit and the vacuum device, The dechlorination treatment unit comprises a dechlorination tank, a first pH regulator storage tank, a catalyst storage tank and a reducing agent storage tank, and the dechlorination tank is connected with the first pH regulator storage tank, the catalyst storage tank and the reducing agent storage tank, The neutralization and coagulation unit comprises a neutralization tank, a waste alkali storage tank and a coagulant storage tank, and the neutralization tank is connected with the waste alkali storage tank and the coagulant storage tank, The biochemical unit comprises a regulating tank, a raw water tank, an anaerobic tank, an aerobic tank, a secondary sedimentation tank, an intermediate reaction tank, a tertiary sedimentation tank, a sand filter tank and a carbon filter tank which are sequentially connected; The dechlorination tank is connected with an external wastewater pipeline and the neutralization tank, and the neutralization tank is connected with the three-effect evaporation device.

2. The processing system of claim 1, wherein, The dechlorination treatment unit comprises at least two dechlorination tanks which are connected in series, and each dechlorination tank is connected with the catalyst storage tank and the reducing agent storage tank, and the dechlorination tank is internally provided with a fluorine-resistant corrosion-resistant layer.

3. The processing system of claim 1, wherein, The three-effect evaporation device comprises a three-effect evaporator, a first-effect evaporator, a second-effect evaporator and a condenser which are sequentially connected, and the vacuum device comprises a vacuum pump and a vacuum filter press, wherein the vacuum pump is connected with each evaporator and the condenser in the three-effect evaporation device, and the vacuum pump is used to make the inside of the three-effect evaporation device in a negative pressure state; the vacuum filter press is connected with a discharge port of the second-effect evaporator in the three-effect evaporation device; The condenser in the three-effect evaporation device is connected with the regulating tank in the biochemical unit, the regulating tank is connected with a second pH regulator storage tank, and the regulating tank is internally provided with a pH sensor, and the regulating tank is used to adjust the pH of the liquid inside to 8-9.

4. The processing system of claim 3, wherein, The liquid outlet of the vacuum filter press is connected to the three-effect evaporator, and the solid outlet of the vacuum filter press is connected to a drying device.

5. The processing system of claim 3, wherein, The gas outlet of the drying device is connected to the biochemical system through an intermediate condenser, and the condensed water generated by the gas condensed by the intermediate condenser directly enters the biochemical system.

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