Search

CN-118184056-B - Treatment system and treatment method for strong complexing heavy metal wastewater in electroplating industry

CN118184056BCN 118184056 BCN118184056 BCN 118184056BCN-118184056-B

Abstract

The invention discloses a treatment system for strongly complexing heavy metal wastewater in the electroplating industry, which comprises an oxidation reaction tank, a Fenton-like reaction tank, a homogenizing regulation tank, a chemical mixing tank, a flocculation tank I, a sedimentation tank I, a heavy metal adsorption tank II, a flocculation tank II and a clean water tank which are sequentially connected, wherein two sludge discharge ports are arranged at the bottom of the sedimentation tank II, one sludge discharge port is connected with the heavy metal adsorption tank through a sludge return pipeline in a backflow manner, and the other sludge discharge port is connected with a regeneration system. The invention also discloses a method for treating the heavy metal wastewater subjected to strong complexing in the electroplating industry based on the treatment system. The method adopts the processes of firstly oxidizing and breaking collaterals, then adding alkali for precipitation and finally modifying zeolite for adsorption to treat the electroplating strong complexing heavy metal wastewater, and can ensure that the concentration of heavy metal ions in the effluent is stably reduced to below 0.1mg/L and reaches the emission standard.

Inventors

  • LUO JIAHAO
  • JIANG QINGQING
  • XIONG JIANGLEI
  • YAN ZHENGCHU
  • XU DONGLEI
  • WANG WENJING
  • ZHOU WEI
  • FENG JIAN

Assignees

  • 江苏中电创新环境科技有限公司

Dates

Publication Date
20260512
Application Date
20240329

Claims (9)

  1. 1. The method for treating the heavy metal wastewater subjected to strong complexation in the electroplating industry is characterized by comprising the following steps of: (1) Adding ferrate into an oxidation reaction tank containing electroplating complexing wastewater until the molar ratio of ferrate to heavy metal ions is n [ Fe (VI) ], wherein n (R m+ ) =2-5:1, regulating the pH of the wastewater to 2-3, and rapidly stirring for reacting for 20-30 min; (2) Sending the effluent of the oxidation reaction tank to a Fenton-like reaction tank, adding ferrous acid salt until the molar ratio of the ferrous acid salt to the ferrate is n [ Fe (II) ]: n [ Fe (VI) ]=5-10:1, regulating the pH of the wastewater to 2-3, and rapidly stirring for reacting for 40-60 min; (3) Delivering the effluent of the Fenton-like reaction tank to a homogenizing regulating tank, regulating the pH of the wastewater to 9.5-10.0, and rapidly stirring for reacting for 15-20 min; (4) Delivering the effluent of the homogenizing adjusting tank to a chemical mixing tank, adding a coagulant into the chemical mixing tank, and rapidly stirring for reacting for 10-15 min; (5) Delivering the water discharged from the chemical mixing tank to a flocculation tank I, adding a flocculating agent into the flocculation tank, stirring at a slow speed, and reacting for 3-5 min; (6) Delivering the effluent of the flocculation tank I to a precipitation tank I, delivering the supernatant after precipitation to a heavy metal adsorption tank, adding a heavy metal adsorbent into the heavy metal adsorption tank until the concentration of the heavy metal adsorbent is 500-1500 mg/L, regulating the pH of the wastewater to be neutral, rapidly stirring, and adsorbing for 40-60 min; (7) Delivering the effluent of the heavy metal adsorption tank to a flocculation tank II, adding a flocculating agent into the effluent, stirring at a slow speed, and reacting for 3-5 min; (8) The effluent of the flocculation tank II is sent to a sedimentation tank II, supernatant fluid after sedimentation is sent to a clean water tank, part of sludge at the bottom of the sedimentation tank is returned to a heavy metal adsorption tank through a sludge return pipe, recycling is completed in the adsorption tank, and the residual sludge is discharged to a regeneration system; The treatment method is realized based on a system which comprises an oxidation reaction tank, a Fenton-like reaction tank, a homogenizing regulating tank, a chemical mixing tank, a flocculation tank I, a sedimentation tank I, a heavy metal adsorption tank, a flocculation tank II, a sedimentation tank II and a clean water tank which are sequentially connected, wherein two sludge discharge ports are arranged at the bottom of the sedimentation tank II, one sludge discharge port is connected with the regeneration system by a sludge return pipeline in a backflow manner to the heavy metal adsorption tank, and the other sludge discharge port is connected with the regeneration system; the heavy metal adsorbent is prepared by the following steps: (1.1) washing natural zeolite with deionized water for 3-5 times, removing impurities on the surface of the zeolite, and soaking the zeolite with deionized water for more than 24 hours, wherein the particle size of the natural zeolite is 40-60 meshes; (1.2) placing the washed zeolite in a muffle furnace, setting the temperature to 400 ℃, and calcining for 2 hours; (1.3) grinding the thermally modified zeolite into 100 mesh powder; (1.4) dissolving 10g of chitosan in 1000mL of acetic acid, fully stirring uniformly to obtain a chitosan-acetic acid solution, adding 20g of zeolite powder in the step (1.3) into 100mL of chitosan-acetic acid solution, heating in a water bath at 60 ℃, and stirring for 8 hours to fully load chitosan on the surface of the activated zeolite, wherein the deacetylation degree of the chitosan is 95% and the mass fraction of acetic acid is 10%; (1.5) cooling the solution after the reaction in the step (1.4) to room temperature, soaking and washing the solution for a plurality of times by deionized water, and placing a solid product obtained after suction filtration in an oven, and drying the solid product at 105 ℃; (1.6) immersing 10g of the organic-supported zeolite powder dried in the step (1.5) in 200mL of DTPA aqueous solution, heating in a water bath at 60 ℃, and stirring for 30min, wherein the concentration of the DTPA aqueous solution is 5mg/mL; And (1.7) centrifuging the solution reacted in the step (1.6), washing the precipitate for many times until no DTPA exists, and drying and aging for 24 hours at 40-50 ℃ to obtain the heavy metal adsorbent.
  2. 2. The method of claim 1, wherein in step (1), the ferrate is potassium ferrate or sodium ferrate.
  3. 3. The method according to claim 1, wherein in the step (1), the initial concentration of the heavy metal ions in the wastewater is 5mg/L to 10mg/L.
  4. 4. The method according to claim 1, wherein in the step (2), the ferrite is ferrous sulfate or ferrous chloride.
  5. 5. The method according to claim 1, wherein the pH-adjusting agents in the steps (1) to (3) and (6) are HCl, H 2 SO 4 and NaOH.
  6. 6. The treatment method according to claim 1, wherein in the step (4), the coagulant is polyaluminum chloride, and the concentration of the coagulant added in the wastewater is 500-1000 mg/L.
  7. 7. The treatment method according to claim 1, wherein in the step (5) and the step (7), the flocculant is polyacrylamide, and the concentration of the flocculant added in the wastewater is 3-5 mg/L.
  8. 8. The treatment method according to claim 1, wherein in the steps (1) - (7), the rotation speed of rapid stirring is 300-350 r/min, and the rotation speed of slow stirring is 130-150 r/min.
  9. 9. The method according to claim 1, wherein 15-20wt% of the sludge in the step (8) is returned to the heavy metal adsorption tank.

Description

Treatment system and treatment method for strong complexing heavy metal wastewater in electroplating industry Technical Field The invention relates to a treatment system of heavy metal wastewater in the electroplating industry, and also relates to a method for treating heavy metal wastewater in the electroplating industry based on the treatment system. Background In the electroplating process of metal parts such as an electronic component bracket, an antenna and the like, a complexing agent is added into a plating solution in order to make a plating layer finer and more stable, so that a large amount of strongly complexing heavy metal wastewater is generated in the electroplating industry. Compared with the traditional wastewater, the electroplating complexing wastewater has the characteristics of large water quantity, large complexing heavy metal ratio, low wastewater conductivity, high ammonia nitrogen concentration and the like. The traditional electroplating complex wastewater treatment methods such as a coagulating sedimentation method, an ion exchange method and an adsorption method can not effectively destroy the annular stable structure of the EDTA complex, and the existing advanced oxidation methods such as Fenton, electrocatalytic oxidation, UV, O 3 and other oxidation decomplexing methods have the problems of large dosing dosage, high sludge yield, difficult effluent reaching standards and high post treatment cost. In addition, heavy metal wastewater is treated by adding a heavy metal scavenger, wherein the heavy metal scavenger is modified by using DTC salt and an auxiliary agent so as to enhance the combination capability of the heavy metal scavenger and low-concentration heavy metal ions, thereby realizing the purpose of stably removing heavy metals. However, the recapturing agent only has a good effect of removing free heavy metal ions in the wastewater, and can not reduce target heavy metal ions to below the standard for heavy metals strongly complexed with EDTA, citric acid and the like, and besides, the recapturing agent mainly takes organic sulfur as a main component, and the residual organic sulfur recapturing agent has high biotoxicity. Disclosure of Invention The invention aims to provide a treatment system for the heavy metal wastewater subjected to strong complexing in the electroplating industry, and the other aim of the invention is to provide a method for treating the heavy metal wastewater subjected to strong complexing in the electroplating industry based on the treatment system. The technical scheme is that the treatment system for the heavy metal wastewater in the electroplating industry comprises an oxidation reaction tank, a Fenton-like reaction tank, a homogenizing regulating tank, a chemical mixing tank, a flocculation tank I, a sedimentation tank I, a heavy metal adsorption tank II, a flocculation tank II and a clean water tank which are sequentially connected, wherein two sludge discharge ports are arranged at the bottom of the sedimentation tank II, one sludge discharge port is connected with the heavy metal adsorption tank in a backflow manner through a sludge backflow pipeline, and the other sludge discharge port is connected with a regeneration system. The method for treating the heavy metal wastewater subjected to strong complexation in the electroplating industry based on the system comprises the following steps: (1) Adding ferrate into an oxidation reaction tank containing electroplating complexing wastewater until the molar ratio of ferrate to heavy metal ions is n [ Fe (VI) ], wherein n (R m+) =2-5:1, regulating the pH of the wastewater to 2-3, and rapidly stirring for reacting for 20-30 min; (2) Sending the effluent of the oxidation reaction tank to a Fenton-like reaction tank, adding ferrous acid salt until the molar ratio of the ferrous acid salt to the ferrate is n [ Fe (II) ]: n [ Fe (VI) ]=5-10:1, regulating the pH of the wastewater to 2-3, and rapidly stirring for reacting for 40-60 min; (3) Delivering the effluent of the Fenton-like reaction tank to a homogenizing regulating tank, regulating the pH of the wastewater to 9.5-10.0 (after regulating the pH to alkalinity, free heavy metals are firstly precipitated in the form of hydroxide, the dosage of the subsequent heavy metal adsorbent is reduced), and rapidly stirring and reacting for 15-20 min; (4) Delivering the effluent of the homogenizing adjusting tank to a chemical mixing tank, adding a coagulant into the chemical mixing tank, and rapidly stirring for reacting for 10-15 min; (5) Delivering the water discharged from the chemical mixing tank to a flocculation tank I, adding a flocculating agent into the flocculation tank, stirring at a slow speed, and reacting for 3-5 min; (6) Delivering the effluent of the flocculation tank I to a precipitation tank I, delivering the supernatant after precipitation to a heavy metal adsorption tank, adding a heavy metal adsorbent into the heavy metal adsorption tank