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

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Example Embodiment

[0046] Example 1:

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

[0048] Take the heavy metal wastewater to be treated, adjust the pH to 5, use a DC power supply, set the electro-flocculation parameters to 15V for each pair of electrodes, and current density to 5mA / cm 2 , The electrode plate spacing is 20mm, the electrode adopts the pure aluminum electrode plate with round hole, carries on the electric flocculation treatment for 30min; after the electric flocculation reaction for 30min, add 4mg / L of the precipitation aid hydrocarbyl amino dithioformate to the reaction solution (DTC salt), continue to settle for 10 minutes to complete the reaction.

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

Example Embodiment

[0050] Example 2:

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

[0052] Take the heavy metal wastewater to be treated, adjust the pH to 7, use a low-voltage pulse power supply, set the electro-flocculation parameters to 20V for each pair of electrodes, and current density to 8mA / cm 2 , The electrode plate spacing is 15mm, the electrode adopts the pure aluminum electrode plate with round hole, carries on the electric flocculation treatment 40min; After the electric flocculation reaction, add 5mg / L of the sedimentation aid hydrocarbyl amino dithioformate ( DTC salt), continue to settle for 20 min to complete the reaction.

[0053] After the electrocoagulation reaction was completed, the concentrations of nickel, lead, cadmium, chromium and mercury ions in the water were determined to be 0.025mg / L, 0.04mg / L, 0.05mg / L, 0.01mg / L and 0.01mg / L, respectively.

Example Embodiment

[0054] Example 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 electro-flocculation parameter to the voltage of each pair of electrodes to 20V, and the current density to 10mA / cm 2 , The electrode plate spacing is 10mm, the electrode adopts the pure aluminum electrode plate with round hole, carries on the electric flocculation treatment for 40min; After the electric flocculation reaction, add 3mg / L of the precipitation aid alkyl amino dithioformate ( DTC salt), continue to settle for 15 min to complete the reaction.

[0057] After the electrocoagulation reaction was completed, the concentrations of nickel, lead, cadmium, chromium and mercury ions in the water 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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