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Method for treating heavy metal wastewater through electric flocculation-chemical precipitation

A technology of chemical precipitation and electrocoagulation, which is applied in the fields of electrocoagulation-chemical precipitation treatment of low-concentration heavy metal wastewater and electrocoagulation-chemical precipitation treatment of heavy metal wastewater. The effect of fixed investment and simple equipment

Inactive Publication Date: 2015-11-18
BEIJING JINGRUN NEW TECH DEV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0006] Aiming at the problems of secondary pollution, low treatment efficiency, easy membrane fouling, low adsorption rate, expensive adsorbent and difficult to regenerate, easy pollution of ion exchange resin, high cost and complicated operation in the existing heavy metal wastewater treatment process, this paper The invention provides a method for electrocoagulation-chemical precipitation treatment of low-concentration heavy metal wastewater

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0047] In the heavy metal wastewater to be treated, the concentration of nickel, lead, cadmium, chromium and mercury ions are all 10mg / L.

[0048] Take the heavy metal wastewater to be treated, adjust the pH value to 5, use DC power supply, set the electrocoagulation parameters as the voltage of each pair of electrodes is 15V, and the current density is 5mA / cm 2 , the distance between the plates is 20mm, the electrode is made of pure aluminum plates with round holes, and the electrocoagulation treatment is carried out for 30 minutes; after the electrocoagulation reaction for 30 minutes, 4 mg / L of the sedimentation aid hydrocarbyl carbamate is added to the reaction solution (DTC salt), continue to settle for 10min to complete the reaction.

[0049] After the electrocoagulation reaction was completed, the concentrations of nickel, lead, cadmium, chromium and mercury in the effluent were determined to be 0.05mg / L, 0.025mg / L, 0.035mg / L, 0.05mg / L and 0.01mg / L respectively.

Embodiment 2

[0051] In the heavy metal wastewater to be treated, the concentration of nickel, lead, cadmium, chromium and mercury ions are all 5mg / L.

[0052] Take the heavy metal wastewater to be treated, adjust the pH value to 7, use a low-voltage pulse power supply, set the electrocoagulation parameters as the voltage of each pair of electrodes is 20V, and the current density is 8mA / cm 2 , the pole plate spacing is 15mm, the electrode adopts the pure aluminum pole plate with round hole, carries out electroflocculation treatment 40min; DTC salt), continue to settle for 20min to complete the reaction.

[0053] After the electrocoagulation reaction is completed, the concentrations of nickel, lead, cadmium, chromium and mercury ions in the effluent water are 0.025mg / L, 0.04mg / L, 0.05mg / L, 0.01mg / L and 0.01mg / L respectively.

Embodiment 3

[0055] In the heavy metal wastewater to be treated, the concentrations of nickel, lead, cadmium, chromium and mercury are all 8mg / L.

[0056] Take the heavy metal wastewater to be treated, adjust the pH value to 6, use a low-voltage pulse power supply, set the electrocoagulation parameters as the voltage of each pair of electrodes is 20V, and the current density is 10mA / cm 2 , the pole plate spacing is 10mm, the electrode adopts the pure aluminum pole plate with round hole, carries out electroflocculation treatment 40min; DTC salt), continue to settle for 15min to complete the reaction.

[0057] After the electrocoagulation reaction was completed, the concentrations of nickel, lead, cadmium, chromium and mercury ions in the effluent were determined to be 0.02mg / L, 0.03mg / L, 0.03mg / L, 0.05mg / L and 0.015mg / L respectively.

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Abstract

The invention provides a method for treating heavy metal wastewater through electric flocculation-chemical precipitation. The method comprises the following steps: regulating the pH value of wastewater, performing electric flocculation treatment in an electric flocculation reactor for 30-60 min, adding a settling agent for sedimentation for 10-30 min and then discharging water. According to the method for treating heavy metal wastewater through electric flocculation-chemical precipitation, provided by the invention, heavy metal wastewater containing trace heavy metal ions is firstly subjected to electric flocculation, ions produced by electrolysis are hydrolyzed to produce a great deal of polyhydroxy compounds, the polyhydroxy compounds are subjected to reaction, absorption and chelation with trace heavy metal ions, therefore a large proportion of heavy metal ions can be gathered, and besides, the settling agent is added for further gathering the heavy metal ions, the settling agent has a synergistic effect with the electrochemical floccules, and at the same time the obtained flocculating constituents start to precipitate, finally, the obtained effluent can be enabled to meet the emission standard.

Description

technical field [0001] The invention belongs to the field of sewage treatment, and relates to a method for treating heavy metal wastewater by electrocoagulation-chemical precipitation, in particular to a method for treating low-concentration heavy metal wastewater by electrocoagulation-chemical precipitation. Background technique [0002] Heavy metal wastewater refers to industrial wastewater containing heavy metal ions such as chromium, cadmium, nickel, and lead. Machinery processing industry, mining smelting industry and some chemical enterprises will produce heavy metal wastewater in the production process. Wastewater has not yet reached the national discharge standard. If it is discharged directly, it will cause water pollution, and through the soil, water, air, especially through the food chain, it will directly cause serious harm to human health. Therefore, the purification of low-concentration heavy metal wastewater containing trace heavy metal ions has become one of...

Claims

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Application Information

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IPC IPC(8): C02F9/06
Inventor 肖东殷进陈宝生金志娜苗远
Owner BEIJING JINGRUN NEW TECH DEV
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