Search

CN-122010337-A - Chromium-containing wastewater treatment and recovery treatment line and recovery treatment method thereof

CN122010337ACN 122010337 ACN122010337 ACN 122010337ACN-122010337-A

Abstract

A chromium-containing wastewater treatment and recovery treatment line and a recovery treatment method thereof are provided, wherein an ion exchange system carries out ion exchange adsorption on hexavalent wastewater, an alkali washing system is connected to the ion exchange system to output alkali liquor, the water washing system is used for outputting cleaning water to the ion exchange system, the acid washing system is used for outputting acid liquor to the ion exchange system, a chromium recovery treatment branching is used for receiving hexavalent wastewater of the ion exchange system, and mixing hexavalent wastewater with sulfur powder and alkali liquor to prepare chromium hydroxide, then chromium hydroxide is subjected to pressure filtration, a chromium hydroxide filter cake is output to a recovery calcination treatment line, pressure filtration liquid is output to a pressure filtration liquid recovery branching, the pressure filtration liquid recovery branching is used for recovering sodium thiosulfate from the pressure filtration liquid, and the recovery calcination treatment line is used for calcining the chromium hydroxide filter cake to Cr 2 O 3 . The scheme realizes the micro-emission and even zero emission targets of the chromium-containing wastewater, and solves the problem of a large amount of chromium-containing hazardous waste sludge generated by relying on a chemical reduction-precipitation method in the traditional chromium-containing wastewater treatment.

Inventors

  • FU WEIXIA
  • WANG FENG
  • GU XIANGHUA
  • LIU HUAHUA
  • LI LE

Assignees

  • 广东广美环保科技有限公司

Dates

Publication Date
20260512
Application Date
20260227

Claims (10)

  1. 1. The chromium-containing wastewater treatment and recovery treatment line is characterized by comprising a resin regeneration treatment branching line, a chromium recovery treatment branching line, a filter pressing liquid recovery branching line and a recovery calcination treatment line; the resin regeneration treatment branching line comprises an ion exchange system, an alkaline washing system, a water washing system and an acid washing system; The system comprises an ion exchange system, an alkaline washing system, an ion exchange system, an ion washing system, an acid washing system and an acid washing system, wherein the ion exchange system is used for receiving hexavalent wastewater and carrying out ion exchange adsorption on the hexavalent wastewater; The input end of the chromium recovery treatment branching is communicated with the output end of the ion exchange system, the output end of the chromium recovery treatment branching is respectively communicated with the filter pressing liquid recovery branching and the recovery calcination treatment line, the chromium recovery treatment branching is used for receiving hexavalent wastewater of the ion exchange system, mixing hexavalent wastewater with sulfur powder and alkali liquor to prepare chromium hydroxide, press-filtering the chromium hydroxide, outputting a chromium hydroxide filter cake to the recovery calcination treatment line, and outputting press-filtered liquid to the filter pressing liquid recovery branching; the filter pressing liquid recovery branching line is used for recovering sodium thiosulfate from the filter pressing liquid; The recovery calcination treatment line is used for calcining the chromium hydroxide filter cake into Cr 2 O 3 .
  2. 2. The chromium-containing wastewater treatment and recovery treatment line according to claim 1 is characterized in that the ion exchange system is provided with an ion exchange column, wherein ion exchange resin is filled in the ion exchange column, a column bottom water distributor and a column bottom aerator are arranged below the ion exchange column, and the column bottom water distributor is provided with a porous distribution plate; the alkaline washing system comprises an alkaline liquid storage tank, an alkaline washing pipe and an alkaline liquid output pump; The alkali liquor storage tank is communicated with the column bottom water distributor through the alkali washing pipe and is used for outputting alkali liquor to the column bottom water distributor, and the alkali liquor is output into the ion exchange column through the porous distribution plate; the water washing system is communicated with the ion exchange column and is used for outputting washing water to the ion exchange column; the acid washing system is communicated with the ion exchange column and is used for outputting acid liquor to the ion exchange column; the ion exchange system also comprises a differential pressure sensing device and a bubble control valve; The detection end of the pressure difference sensing device is positioned in the ion exchange column and is close to the ion exchange resin, the pressure difference sensing device is in communication connection with the bubble control valve, and the bubble control valve is arranged on the micropore aerator pipe.
  3. 3. The chromium-containing wastewater treatment recovery treatment line according to claim 2, wherein the ion exchange system comprises a serial pipe, an internal valve, an external connecting pipe, an external valve, an adsorption monitoring device, a head column valve and a plurality of ion exchange columns; The ion exchange columns are connected in series, and one output end of one ion exchange column is communicated with the input end of the other ion exchange column through the serial pipe; The ion exchange column is provided with at least two input ends, one input end is used for connecting the serial pipes, the other input end is provided with the head column valve, the column bottom water distributor is communicated with the alkaline washing pipe through the outer connecting pipe, the outer valve is arranged on the outer connecting pipe, the ion exchange column is provided with the adsorption monitoring device, and the adsorption monitoring device is connected with the inner valve and the outer valve in a communication mode.
  4. 4. The chromium-containing wastewater treatment recovery treatment line according to claim 1, wherein the chromium recovery treatment line comprises a recovery reactor, a reducing agent feeder, an alkali liquor feeder and a recovery filter-pressing system; The recovery reactor is used for receiving hexavalent chromium wastewater separated by resin regeneration treatment, the output end of the reducing agent feeder is communicated with the recovery reactor and used for outputting sulfur powder to the recovery reactor, and the output end of the alkali liquid feeder is communicated with the recovery reactor and used for outputting alkali liquid to the recovery reactor so as to treat the hexavalent chromium wastewater of the recovery reactor into chromium hydroxide wastewater; the output end of the recovery reactor is communicated with the recovery filter pressing system and is used for outputting chromium hydroxide wastewater to the recovery filter pressing system; The recovery filter pressing system comprises a primary filter press, a filter crushing device, a cleaning tank and a secondary filter press; The primary filter press is used for receiving the chromium hydroxide wastewater of the recovery reactor, performing filter pressing treatment on the chromium hydroxide wastewater, outputting filtrate to the filter pressing liquid recovery branching line, and outputting chromium hydroxide to the filter crushing device; the filtering and crushing device is used for crushing chromium hydroxide and outputting the chromium hydroxide to the cleaning tank; The cleaning tank is used for cleaning chromium hydroxide and outputting the chromium hydroxide to the secondary filter press; And the secondary filter press is used for performing filter pressing treatment on the chromium hydroxide in the cleaning tank to obtain the chromium hydroxide.
  5. 5. The chromium-containing wastewater treatment recovery treatment line according to claim 4, further comprising a calcination atmosphere control system and an exhaust gas treatment branching line; the recovery calcination treatment line comprises a calcination pulverizer, a conveyor and a calcination kiln; The calcination pulverizer is used for receiving the chromium hydroxide of the secondary filter press and pulverizing the chromium hydroxide; the conveying end of the conveyor is used for receiving chromium hydroxide of the calcination pulverizer and conveying the chromium hydroxide to pass through the calcination kiln; The calcining kiln is used for calcining chromium hydroxide, and is sequentially provided with a heating zone, a heat preservation zone and a cooling zone from an input port to an output port; the temperature of the heating area is 500-680 ℃, the temperature of the heat preservation area is 1050-1100 ℃, and the temperature of the cooling area is 20-80 ℃; The calcination atmosphere control system comprises a shielding gas output device, an oxygen detection device and an infrared gas analysis device; The exhaust gas treatment branching line, the oxygen detection device and the infrared gas analysis device are in communication connection, the input end of the exhaust gas treatment branching line is communicated with the heat preservation area and used for discharging tail gas of the heat preservation area, the detection ends of the oxygen detection device and the infrared gas analysis device are arranged in the heat preservation area, and the output end of the shielding gas output device is communicated with the heat preservation area and used for outputting shielding gas to the heat preservation area.
  6. 6. The chromium-containing wastewater treatment recovery treatment line according to claim 5, wherein the exhaust gas treatment branching line comprises an exhaust gas main pipe, a desulfurizing tower and an exhaust gas fan; The waste gas blower is arranged at the output end above the desulfurizing tower, and when the waste gas blower is started, the interior of the desulfurizing tower and the waste gas main pipe form negative pressure; The inside of desulfurizing tower is equipped with spray set, spray set is used for to the inside spraying alkaline liquid drop of desulfurizing tower.
  7. 7. The chromium-containing wastewater treatment recovery treatment line according to claim 1 or 4, wherein the filter pressing liquid recovery branching line comprises a multi-effect evaporator, a recovery crystallization kettle, a recovery centrifugal device and a recovery drying device; The multi-effect evaporator is used for receiving the pressure filtrate of the chromium recovery treatment branching line, and the pressure filtrate sequentially passes through the separation chambers of the multiple sub-effect evaporation units and then enters the separation chambers of the single-effect evaporation units; the separation chamber of the first-effect evaporation unit is communicated with the recovery crystallization kettle and is used for outputting pressure filtrate to the recovery crystallization kettle; the recovery crystallization kettle is used for cooling and crystallizing the filter pressing liquid to separate out sodium thiosulfate from the filter pressing liquid to form sodium thiosulfate crystal slurry; the recovery centrifugal device is used for receiving the sodium thiosulfate crystal slurry of the recovery crystallization kettle, carrying out solid-liquid separation on the sodium thiosulfate crystal slurry, and outputting the sodium thiosulfate solid to the recovery drying device; And the recovery drying device is used for drying the sodium thiosulfate solid.
  8. 8. The chromium-containing wastewater treatment recovery treatment line according to claim 7, further comprising a water storage mechanism; the water storage mechanism comprises a water storage pipe, a system water storage tank and a cleaning connecting pipe; The input end of the water storage pipe is respectively communicated with the heating chamber of the split-effect evaporation unit and the heating chamber of the one-effect evaporation unit, the output end of the water storage pipe is communicated with the system water storage tank and is used for receiving condensed water of the multi-effect evaporator and outputting the condensed water to the system water storage tank, the input end of the cleaning connecting pipe is communicated with the system water storage tank, and the cleaning connecting pipe is provided with a cleaning pump body.
  9. 9. A chromium-containing wastewater treatment recovery treatment method using the chromium-containing wastewater treatment recovery treatment line according to any one of claims 1 to 8, characterized by comprising the steps of: The method comprises the steps of S1, when the concentration of Cr ions in an ion exchange column rises to a preset threshold value, switching in an alkaline washing system to the ion exchange system, switching on an alkaline liquid output pump, enabling an alkaline liquid storage tank to output alkaline liquid to the ion exchange column through an alkaline washing pipe, enabling the alkaline liquid to be output below the ion exchange column through a water distributor at the bottom of the column, and enabling the liquid level of the alkaline liquid to pass through ion exchange resin from bottom to top; S2, opening an aerator at the bottom of the column, outputting compressed gas to the ion exchange column through a microporous aerator pipe, and forming bubbles in alkali liquor by the compressed gas through the microporous aerator pipe; S3, the washing system is connected to the ion exchange system, the washing system outputs washing water to the ion exchange column to remove alkali liquor in the ion exchange column, and the washing system is disconnected until the liquid in the ion exchange column is colorless; S4, outputting hexavalent chromium wastewater to a recovery reactor, adding sulfur powder into the hexavalent chromium wastewater of the recovery reactor by a reducing agent feeder, stirring, reducing Cr 6+ into Cr 3+ by the sulfur powder, adding alkali liquor into the recovery reactor by an alkali liquor feeder, and generating Cr (OH) 3 sediment; S5, conveying the chromium hydroxide wastewater to a primary filter press, and carrying out filter pressing treatment on the chromium hydroxide wastewater by the primary filter press, wherein the chromium hydroxide is pressed into a filter cake, and outputting the filtrate to a recovery filter pressing system for recovering sodium thiosulfate; S6, conveying the chromium hydroxide to a secondary filter press, and carrying out filter pressing treatment on the chromium hydroxide by the secondary filter press, wherein the chromium hydroxide is pressed into a filter cake to obtain Cr (OH) 3 ; And S7, conveying the Cr (OH) 3 material into a calcining kiln through a conveyor, and calcining to obtain Cr 2 O 3 .
  10. 10. The method of claim 9, wherein in the step S1, a plurality of ion exchange columns are connected in series, an adsorption monitoring device is arranged on the ion exchange columns, the adsorption monitoring device monitors the concentration of chromium output by the ion exchange columns, when the detection value of the first ion exchange column is continuously more than 3mg/L, the ion exchange column with the adsorption end point is judged to reach the adsorption end point, the ion exchange column with the adsorption end point is isolated from an ion exchange system, S2-S3 is executed, a head column valve is opened on the next ion exchange column with the adsorption end point, and hexavalent chromium wastewater is continuously introduced into the ion exchange column; In the step S3, the cleaning water passes through the ion exchange resin from bottom to top, and after the pH value of the ion exchange column is reduced to 7-9, the cleaning water passes through the ion exchange column from top to bottom, so that the pH value of the ion exchange column is less than or equal to 8.5; Step S7 includes the steps of: S71, conveying the Cr (OH) 3 filter cake obtained in the step S5 to a calcination pulverizer for crushing treatment, and conveying Cr (OH) 3 materials to a calcination kiln through a conveyor; S72, feeding Cr (OH) 3 material into a heating area of the calcining kiln, wherein the temperature of the heating area is 500-680 ℃ so as to reduce the moisture to below 1.2%; s73, cr (OH) 3 enters a heat preservation area of a calcining kiln, the temperature of the heat preservation area is 1050-1100 ℃, cr (OH) 3 is calcined to generate Cr 2 O 3 , an oxygen detection device is used for detecting the O 2 content of the heat preservation area in real time, an infrared gas analysis device is used for detecting the H 2 O content in real time, and when the oxygen content or the water vapor content exceeds a preset threshold value, a shielding gas output device is used for improving the output quantity of shielding gas and increasing the exhaust quantity of a waste gas treatment branching line; and S74, cr 2 O 3 enters a cooling area of the calcining kiln, wherein the initial temperature of the cooling area is less than 80 ℃, and the temperature of the end section of the cooling area is room temperature.

Description

Chromium-containing wastewater treatment and recovery treatment line and recovery treatment method thereof Technical Field The invention relates to the field of chromium-containing wastewater treatment, in particular to a chromium-containing wastewater treatment recovery treatment line and a recovery treatment method thereof. Background The chromium-containing wastewater is used as typical high-toxicity and difficult-to-treat waste liquid in the industrial field and widely used in production links such as electroplating, tanning, pigment synthesis, stainless steel pickling, chemical catalysis and the like. In an electroplating workshop, chromic acid solution is largely used in the surface treatment process of metal parts, so that the concentration of hexavalent chromium (Cr (VI)) in the cleaning wastewater is often hundreds to thousands of mg/L, the pH value is generally lower than 3.0, and the solution is in a strong acid dark yellow liquid state and has strong oxidability and cell penetrating capacity. Cr (VI) can easily enter organisms through cell membranes in the form of chromic acid radical (CrO 4²-), and can generate active oxygen free radicals in the in-vivo reduction process to trigger DNA fragmentation and mutation, and is listed as a class I cancerogenic substance by the International agency for research on cancer (IARC), and the environmental hazard is far more than trivalent chromium (Cr (III)). Even if the low-concentration discharge is carried out, the water can be accumulated in water sediments for a long time, and ecological and human health are threatened after the water is enriched by a food chain. At present, the main stream treatment technology still takes a chemical precipitation method as the main stream, and a typical process is a reduction-neutralization-flocculation sedimentation process, namely sodium metabisulfite or ferrous salt is added into a dosing tank, cr (VI) is reduced into Cr (III) under the condition of pH 2-3, and then the pH is raised to 8-9 to generate Cr (OH) 3 precipitate. The method has simple operation and low construction cost, but can produce about 10 kg chromium-containing sludge per ton of wastewater, belongs to HW21 type hazardous wastes of national hazardous waste list, needs to be entrusted with qualification unit for disposal, and has high annual operation cost. And the sludge has high water content and is easy to harden, the heavy metal dissolution risk exists, and the landfill or solidification treatment still has the hidden trouble of secondary pollution. In addition, the quality of the effluent is greatly influenced by the fluctuation of the inflow water, and the requirement of the special limit value of less than or equal to 0.1 g/L of electroplating pollutant emission standard (GB 21900-2008) is difficult to continuously and stably reach. The traditional ion exchange method relies on the selective adsorption of strong alkaline anion resin to Cr 2O7²-, and the discharged water Cr (VI) can be reduced to below 0.1 mg/L, so that the method is suitable for advanced treatment scenes. However, after resin saturation, high-concentration NaOH or NaCl is needed for analysis and regeneration, the generated regenerated waste liquid contains Cr (VI), cl -、SO4²- and organic dissolved matters, the components are complex, the chromaticity is high, the COD is obviously increased, a multi-stage membrane separation or advanced oxidation unit is needed to be matched for subsequent treatment, and the system energy consumption and the medicament consumption are greatly increased. More importantly, the prior art generally lacks effective conversion and productization paths for chromium element in eluent, has serious resource loss and can not realize real closed-loop treatment. Disclosure of Invention The invention aims to provide a chromium-containing wastewater treatment and recovery treatment line which is provided with a resin regeneration treatment branching line, a chromium recovery treatment branching line, a filter pressing liquid recovery branching line and a recovery calcination treatment line, wherein the process not only effectively blocks migration and biological enrichment risks of hexavalent chromium in the environment, but also avoids long-term ecological hidden danger and supervision pressure caused by chromium-containing sludge landfill. The invention also provides a chromium-containing wastewater treatment and recovery treatment method, which uses the chromium-containing wastewater treatment and recovery treatment line. To achieve the purpose, the invention adopts the following technical scheme: A chromium-containing wastewater treatment and recovery treatment line comprises a resin regeneration treatment branching line, a chromium recovery treatment branching line, a filter pressing liquid recovery branching line and a recovery calcination treatment line; the resin regeneration treatment branching line comprises an ion exchange system, an alkaline washi