A system for treating hazardous waste incineration sulfur-containing washing wastewater in conjunction with hexavalent chromium waste liquid

Abstract

The utility model discloses a system for treating sulfur-containing washing wastewater from hazardous waste incineration in coordination with hexavalent chromium waste liquid, including a flue gas washing device, a first regulating tank, a hexavalent chromium waste liquid storage tank, a reactor, a second regulating tank, a filtering device and an evaporating device; the flue gas washing device is connected to the first regulating tank, the first regulating tank and the hexavalent chromium waste liquid storage tank are both connected to the reactor, the discharge port of the reactor is connected to the second regulating tank, and the second regulating tank is connected to the filtering device; the liquid outlet of the filtering device is connected to the evaporating device, the evaporating device is provided with a liquid return pipe, and the liquid return pipe is connected to the flue gas washing device; the slag outlet of the filtering device is connected to a collecting device. The utility model can simultaneously treat sulfur-containing washing wastewater from hazardous waste incineration and hexavalent chromium waste liquid, saving a large amount of reagent costs, simplifying the process, and obtaining a relatively pure chloride salt product, which has good economic value.

Description

Technical Field

[0001] The utility model relates to the technical field of wastewater treatment, in particular to a system for treating hazardous waste incineration sulfur-containing washing wastewater in coordination with hexavalent chromium waste liquid. Background Art

[0002] During the incineration of hazardous waste, spray washing is usually used to absorb acidic gases such as sulfur dioxide and hydrogen chloride in the flue gas. According to tests, the sulfite in some washing wastewater is 4% to 6%, the chloride ion is 0.5% to 1%, and the remaining anions such as sulfate, carbonate, and fluoride ions account for about 1%. In the prior art, washing wastewater is usually reused as quenching wastewater in the front-end process quenching tower. However, due to the high salt content of this washing wastewater, it is easy to cause coking in the quenching tower, which is not a long-term solution. In addition, there is a technology that performs single-effect or multi-effect evaporation on the washing wastewater after pretreatment, and reuses the distillate as washing make-up water, and the evaporated salt residue is used for hazardous waste disposal; for example, the Chinese patent with publication number CN201810464028 mentions an online desalination and reuse system for hazardous waste incineration flue gas washing wastewater, which uses filtration, coagulation sedimentation, ultrafiltration, reverse osmosis, evaporation crystallization and other processes to treat the washing wastewater, which can effectively remove the salt in the washing wastewater and achieve the purpose of recycling the washing wastewater. However, this technology has a complex process flow, high investment cost, and the waste salt cannot be recycled; in addition, most of the waste salt is mainly sulfite, which is easy to emit sulfur dioxide during the evaporation and crystallization process, and its practical application is limited.

[0003] Chromium in chromium-containing wastewater generally exists in the form of hexavalent chromium and trivalent chromium. The chromium in wastewater is very toxic, among which hexavalent chromium is the most toxic. It is a carcinogenic substance that can cause lung cancer, intestinal diseases and anemia, and is listed as a Class I hazardous substance in the country. The hexavalent chromium waste liquid from the electroplating industry has a hexavalent chromium concentration of about 50,000 ppm and is strongly acidic. The conventional disposal method is to add a large amount of reducing substances such as sulfites or ferrous salts to reduce the hexavalent chromium and then add alkaline substances to precipitate trivalent chromium to achieve the purpose of removing heavy metal chromium. However, this traditional treatment method is costly and produces a large amount of high-salt wastewater after disposal, which increases the difficulty of secondary treatment.

[0004] In summary, the utility model aims to develop a system for treating sulfur-containing washing wastewater from hazardous waste incineration in coordination with hexavalent chromium waste liquid, so as to solve the problem of limited reuse of sulfur-containing washing wastewater from hazardous waste incineration and reduce the disposal cost of hexavalent chromium wastewater, thereby achieving the purpose of coordinated and safe disposal. Utility Model Content

[0005] The technical problem solved by the utility model is to provide a system for treating sulfur-containing washing wastewater from hazardous waste incineration in coordination with hexavalent chromium waste liquid, so as to solve the shortcomings of the above-mentioned background technology.

[0006] The technical problem solved by the utility model is achieved by the following technical solutions:

[0007] A system for treating sulfur-containing washing wastewater from hazardous waste incineration in conjunction with hexavalent chromium waste liquid comprises a flue gas washing device, a first regulating tank, a hexavalent chromium waste liquid storage tank, a reactor, a second regulating tank, a filtering device and an evaporating device; the flue gas washing device is connected to the first regulating tank, the first regulating tank and the hexavalent chromium waste liquid storage tank are both connected to the reactor, the discharge port of the reactor is connected to the second regulating tank, and the second regulating tank is connected to the filtering device; the liquid outlet of the filtering device is connected to the evaporating device, the evaporating device is provided with a liquid return pipe, and the liquid return pipe is connected to the flue gas washing device; the slag outlet of the filtering device is connected to a collecting device.

[0008] In the utility model, a smoke inlet is arranged at the lower part of the smoke scrubbing device, and the smoke scrubbing device is provided with a circulating spraying mechanism.

[0009] In the utility model, a pH sensor and a TDS sensor are arranged in the first regulating tank.

[0010] In the utility model, the first regulating tank and the hexavalent chromium waste liquid storage tank are both connected to the reactor through a feed pipe, and a flow meter and a regulating valve are both provided on the feed pipe.

[0011] In the utility model, the second regulating tank is connected to the alkali solution storage tank, and a pH sensor is arranged in the second regulating tank.

[0012] The utility model also includes a controller, and the circulating spray mechanism, the pH sensor and TDS sensor arranged in the first regulating tank, the flow meter and regulating valve arranged on the feed conveying pipe, and the pH sensor arranged in the second regulating tank are all electrically connected to the controller.

[0013] In the utility model, the evaporation device is a single-effect evaporation device.

[0014] In the utility model, the first regulating tank, the hexavalent chromium waste liquid storage tank, the second regulating tank and the reaction kettle are all provided with stirring mechanisms.

[0015] Beneficial effects: The hazardous waste incineration sulfur-containing washing wastewater and hexavalent chromium waste liquid treatment system described in the utility model utilizes sulfite in the incineration washing wastewater to reduce and treat the hexavalent chromium waste liquid, and utilizes the acid in the hexavalent chromium waste liquid to remove carbonate in the incineration washing wastewater. The fluoride salt in the washing wastewater and the sulfate produced by the reduction of hexavalent chromium are removed by alkaline solution treatment in the second regulating tank. The chloride salt in the washing wastewater is effectively removed and recovered by the evaporation device. Compared with the traditional treatment system, two kinds of wastewater can be treated at the same time, a large amount of chemical cost can be saved, and the process can be simplified. The distillate in the evaporation device can be reused as washing replenishment water to save water resources. Finally, the utility model can also obtain a relatively pure chloride salt product with good economic value. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of a preferred embodiment of the utility model.

[0017] Among them: 1. Flue gas scrubbing device; 11. Circulating spray mechanism; 111. Circulating pump; 112. Spray net; 2. First regulating tank; 3. Hexavalent chromium waste liquid storage tank; 4. Reactor; 5. Second regulating tank; 6. Alkali liquid storage tank; 7. Filtering device; 8. Evaporating device; 9. Collecting device; 10. Liquid return pipe. DETAILED DESCRIPTION

[0018] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further described below with reference to specific illustrations.

[0019] See also Figure 1 A system for treating sulfur-containing washing wastewater from hazardous waste incineration in conjunction with hexavalent chromium waste liquid comprises a flue gas washing device 1, a first regulating tank 2, a hexavalent chromium waste liquid storage tank 3, a reactor 4, a second regulating tank 5, a filtering device 7 and an evaporating device 8.

[0020] like Figure 1 As shown, the flue gas scrubbing device 1 includes a scrubbing tower, a flue gas inlet is arranged in the middle and lower part of the scrubbing tower, and the flue gas enters the scrubbing tower from the middle and lower part. The flue gas scrubbing device 1 also includes a circulating spraying mechanism 11, and the circulating spraying structure includes a circulating pump 111 and a multi-layer spraying net 112 connected to the circulating pump 111, so that circulating spraying can be performed. The spraying net 112 is arranged in the middle and upper part of the scrubbing tower. In a preferred embodiment, an adsorption layer can be arranged between the multi-layer spraying nets 112.

[0021] The flue gas scrubbing device 1 is connected to the first regulating tank 2, in which a pH sensor and a TDS sensor are arranged. The washing wastewater in the flue gas scrubbing device 1 enters the first regulating tank 2, and after the pH value of the washing wastewater is adjusted to about 8.2 in the first regulating tank 2, and the TDS in the washing wastewater is adjusted to about 10%, the washing wastewater enters the reactor 4. In practical applications, the setting of the first regulating tank 2 is more critical. If the pH of the washing wastewater is greater than 8.2, excessive bicarbonate ions will be produced to reduce the proportion of sulfite ions in the washing wastewater, and more raw alkali will be consumed and the amount of salt-containing wastewater will be increased; when TDS is greater than 10%, the salt content in the washing water will be too high, and some salt will precipitate crystals to block the filling and pipeline of the washing tower.

[0022] The first regulating tank 2 and the hexavalent chromium waste liquid storage tank 3 are both connected to the reactor 4. The first regulating tank 2 and the hexavalent chromium waste liquid storage tank 3 are both connected to the reactor 4 through a feed pipe. The feed pipe is provided with a flow meter and a regulating valve. The flow meter and the regulating valve control the ratio of the washing wastewater and the hexavalent chromium waste liquid entering the reactor 4. The mass ratio of sulfur in the incineration washing wastewater to chromium in the hexavalent chromium waste liquid is 4 to 5:1. When the mass ratio of sulfur in the incineration washing wastewater to chromium in the hexavalent chromium waste liquid is greater than 5:1, part of the sulfite ions will not be completely oxidized, and the sulfite entering the single-effect evaporation system will affect the quality of the single-effect distillate and the salt slag. When the mass ratio of sulfur in the incineration washing wastewater to chromium in the hexavalent chromium waste liquid is less than 4:1, part of the hexavalent chromium will not be reduced, and the disposal effect is not ideal. In actual operation, the preferred solution is to use an X-ray fluorescence spectrometer to quickly and quantitatively detect the sulfur content in the washing wastewater and the chromium content in the hexavalent chromium waste liquid, so that the mass ratio of sulfur in the washing wastewater to chromium in the hexavalent chromium waste liquid entering the reactor 4 is 4 to 5: 1. During the reaction process, the sulfite in the washing wastewater can fully reduce the hexavalent chromium, and the acid in the hexavalent chromium waste liquid can remove the carbonate in the washing wastewater.

[0023] The discharge port of the reactor 4 is connected to the second regulating tank 5, and the second regulating tank 5 is connected to the alkali solution storage tank 6. A pH sensor is arranged in the second regulating tank 5. The alkali solution storage tank 6 is preferably a calcium hydroxide storage tank, and the pH value of the liquid in the second regulating tank 5 is adjusted to 10-11 by calcium hydroxide. Calcium ion precipitation effectively removes fluoride salts in the washing wastewater and sulfates produced by reducing hexavalent chromium, thereby achieving the purpose of reducing the salt content in the washing wastewater and enabling reuse. When the pH is less than 10, the chromium is not completely precipitated, causing the chromium element to enter the washing tower and affect the quality of the washing water; when the pH is greater than 11, the calcium hydroxide is excessive, resulting in excessive waste of calcium hydroxide and affecting the quality of the salt slag, so the real-time monitoring data of the pH sensor is extremely important.

[0024] In addition, the second regulating tank 5 can remove excess sulfite in the solution by connecting to the calcium hydroxide provided by the alkali solution storage tank 6, thereby preventing sulfite in the washing wastewater from entering the evaporation device 8, thereby preventing sulfur dioxide from being easily emitted during the evaporation and crystallization process and affecting the steam quality.

[0025] The second regulating tank 5 is connected to the filter device 7; the filter device 7 is preferably a plate-frame filter press, and the liquid outlet of the filter device 7 is connected to the evaporation device 8, which is preferably a single-effect evaporation device 8. The chlorine salt in the incineration and washing wastewater is effectively removed and recovered through single-effect evaporation, and the obtained chlorine salt is relatively pure, which can achieve resource recovery. The evaporation device 8 is provided with a return pipe 10, and the return pipe 10 is connected to the flue gas washing device 1. The distillate in the single-effect evaporation process can be reused as washing water, which greatly saves water resources and realizes the recycling of incineration and washing wastewater.

[0026] The slag outlet of the filtering device 7 is connected to the collecting device 9, which can be a collection tank or a collection bag; the collected filter residue can be landfilled.

[0027] In this embodiment, the first regulating tank 2, the hexavalent chromium waste liquid storage tank 3, the second regulating tank 5, and the reactor 4 are all provided with stirring mechanisms, so as to promote the uniformity of the feed or improve the sufficiency of the reaction.

[0028] As an improvement to this embodiment, a controller is further included, and the circulating spray mechanism 11, the pH sensor and TDS sensor provided in the first regulating tank 2, the flow meter and regulating valve provided on the feed pipe, and the pH sensor provided in the second regulating tank 5 are all electrically connected to the controller, so that certain automatic control can be achieved.

[0029] The utility model is used to treat sulfur-containing washing wastewater and hexavalent chromium waste liquid from the incineration of hazardous waste, wherein the pH of the incineration washing wastewater is 8, the total dissolved solids are 100000 mg / L, and the pH of the hexavalent chromium waste liquid is less than 1. The X-ray fluorescence spectrometer is used for rapid quantitative detection and adjustment so that the sulfur content of the washing wastewater in the first adjustment tank is 2.0%, and the chromium content of the hexavalent chromium waste liquid in the hexavalent chromium waste liquid storage tank is 5.0%. According to the sulfur and chromium mass ratio of 4.5:1, the washing wastewater and the hexavalent chromium waste liquid are transported to the reactor, and then continuously mixed and stirred to reduce the hexavalent chromium with sulfite, and at the same time, the carbonate is decomposed into carbon dioxide by the acid in the hexavalent chromium waste liquid and removed; after the reaction is complete, it is transported to the second adjustment tank and calcium hydroxide is added to adjust the solution pH to 10; then the solution is output to the filter device for plate and frame filter pressing, the filter residue is landfilled, the filtrate enters the evaporation device, and the evaporated filtrate is reused as washing water, and the filter residue is a relatively pure chloride salt product.

[0030] The obtained single-effect evaporation distillate and single-effect evaporation salt residue were tested and analyzed, wherein the single-effect evaporation distillate and filtrate were tested for the total soluble solid content using the water and wastewater monitoring and analysis method (fourth edition supplement) 3.1.7.2 103-105℃ dried filterable residue. The single-effect evaporation salt residue was quantitatively analyzed for sulfur and chromium elements using an X-ray fluorescence spectrometer. The test results are shown in Table 1.

[0031] Table 1

[0032]

[0033] As shown in Table 1, the total soluble solid content in the washing wastewater treated by the system described in the utility model is reduced from 100,000 mg / L to 200-300 mg / L, meeting the requirements for the reuse of incineration washing wastewater; and the single-effect evaporation salt residue basically does not contain sulfur and chromium, and the salt residue is relatively pure and meets the basic requirements of resource recovery. The utility model can more effectively utilize the valuable substances in the incineration washing wastewater, reduce the cost of raw materials, and effectively increase the benefits of hazardous waste disposal.

[0034] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0035] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present utility model, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0036] In the present utility model, unless otherwise clearly stipulated and limited, the terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal connection of two elements.

[0037] The above contents are further detailed descriptions of the present invention in combination with specific implementation methods, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention.

Claims

1. A system for treating sulfur-containing washing wastewater from hazardous waste incineration in conjunction with hexavalent chromium waste liquid, characterized in that: It comprises a flue gas washing device, a first regulating tank, a hexavalent chromium waste liquid storage tank, a reactor, a second regulating tank, a filtering device and an evaporating device; the flue gas washing device is connected to the first regulating tank, the first regulating tank and the hexavalent chromium waste liquid storage tank are both connected to the reactor, the discharge port of the reactor is connected to the second regulating tank, and the second regulating tank is connected to the filtering device; the liquid outlet of the filtering device is connected to the evaporating device, the evaporating device is provided with a liquid return pipe, and the liquid return pipe is connected to the flue gas washing device; the slag outlet of the filtering device is connected to the collecting device.

2. The system for treating sulfur-containing washing wastewater from hazardous waste incineration in conjunction with hexavalent chromium waste liquid according to claim 1, characterized in that: A smoke inlet is arranged at the lower part of the smoke scrubbing device, and the smoke scrubbing device is provided with a circulating spraying mechanism.

3. The system for treating sulfur-containing washing wastewater from hazardous waste incineration in conjunction with hexavalent chromium waste liquid according to claim 2, characterized in that: The first regulating tank is provided with a pH sensor and a TDS sensor.

4. The system for treating sulfur-containing washing wastewater from hazardous waste incineration in conjunction with hexavalent chromium waste liquid according to claim 3 is characterized in that: The first regulating tank and the hexavalent chromium waste liquid storage tank are both connected to the reactor through a feed pipe, and a flow meter and a regulating valve are provided on the feed pipe.

5. The system for treating sulfur-containing washing wastewater from hazardous waste incineration in conjunction with hexavalent chromium waste liquid according to claim 4, characterized in that: The second regulating tank is connected to the alkali solution storage tank, and a pH sensor is arranged in the second regulating tank.

6. The system for treating sulfur-containing washing wastewater from hazardous waste incineration in conjunction with hexavalent chromium waste liquid according to claim 5 is characterized in that: It also includes a controller, and the circulating spray mechanism, the pH sensor and TDS sensor arranged in the first regulating tank, the flow meter and regulating valve arranged on the feed conveying pipe, and the pH sensor arranged in the second regulating tank are all electrically connected to the controller.

7. The system for treating sulfur-containing washing wastewater from hazardous waste incineration in conjunction with hexavalent chromium waste liquid according to claim 1, characterized in that: The evaporation device is a single-effect evaporation device.

8. The system for treating sulfur-containing washing wastewater from hazardous waste incineration in conjunction with hexavalent chromium waste liquid according to claim 1, characterized in that: The first regulating tank, the hexavalent chromium waste liquid storage tank, the second regulating tank and the reactor are all provided with stirring mechanisms.

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