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Method for treating chromium-containing wastewater by using continuous pulse electrocoagulation technology

A technology for technical treatment and treatment of wastewater, applied in chemical instruments and methods, multi-stage water/sewage treatment, water/sludge/sewage treatment, etc. , achieve the effect of overcoming poor treatment effect, increasing treatment capacity and alleviating concentration polarization

Inactive Publication Date: 2013-09-18
江苏通瑞环保科技发展股份有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the main problems at present are high energy consumption, and concentration polarization is prone to occur during the reaction process, which leads to electrode passivation and reduces processing efficiency. At the same time, there is also the problem of cumbersome cleaning of the electrolytic cell

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0008] Example 1: The content of chromium-containing wastewater is 100mg / L, the pH value is adjusted to 3, the conductivity is 3000us / cm, the feed rate is 15ml / min, aluminum electrodes are used, the distance between the plates is 1cm, and the average current density is 10mA / cm 2 , the duty cycle of the double pulse power supply is 0.6, the frequency is 0.5KHz, the power-on period is 0.4ms, and the power-off period is 0.3ms. Samples are taken every 15min, and the absorbance is measured after the centrifugation time is 10min. As the reaction progresses, Cr 6+ The removal rate increases gradually, tends to be stable at 95min, and the electrolysis time is 180min, at this time Cr 6+ The removal rate reaches 99.5%.

Embodiment 2

[0010] Example 2: The content of chromium-containing wastewater is 100mg / L, the pH value is adjusted to 4, the conductivity is 2000us / cm, the feed rate is 10ml / min, iron electrodes are used, the distance between the plates is 1.5cm, and the average current density is 9mA / cm 2 , the duty cycle of the single pulse power supply is 0.2, the frequency is 2KHz, the power-on period is 0.9ms, and the power-off period is 1ms. Samples are taken every 15min, and the absorbance is measured after the centrifugation time is 8min. As the reaction progresses, Cr 6+ The removal rate increases gradually, tends to be stable at 90min, and the electrolysis time is 160min, at this time Cr 6+ The removal rate reached 99.3%.

[0011] Comparative example: the waste water of the same type, concentration and pH value as mentioned above is electrolyzed by DC power supply, and the treated waste water Cr 6+ The removal rate reaches 95.3%, after calculation, the power consumption increases by 31.4%.

Embodiment 3

[0012] Example 3: The content of chromium-containing wastewater is 100mg / L, the pH value is adjusted to 5, the conductivity is 1000us / cm, the feed rate is 10ml / min, aluminum electrodes are used, the distance between the plates is 1.8cm, and the average current density is 6mA / cm 2 , the duty cycle of the double pulse power supply is 0.8, the frequency is 2KHz, the power-on period is 0.8ms, and the power-off period is 0.6ms. Samples are taken every 15min, and the absorbance is measured after the centrifugation time is 10min. As the reaction progresses, Cr 6+ The removal rate increases gradually, tends to be stable at 90min, and the electrolysis time is 120min, at this time Cr 6+ The removal rate reached 98.8%.

[0013] Comparative example: the waste water of the same type, concentration and pH value as mentioned above is electrolyzed by DC power supply, and the treated waste water Cr 6+ The removal rate reaches 94.5%, after calculation, the power consumption increases by 35.5%....

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Abstract

The invention discloses a method for treating chromium-containing wastewater by using a continuous pulse electrocoagulation technology. The method comprises the steps of: firstly adjusting the wastewater to have the pH of 3-7 and the conductivity of 500-3,000 us / cm; then carrying out continuous electrocoagulation treatment, wherein the feeding rate is 10-20 ml / min, a pulse power supply is used for controlling the output current density to be 2-10 mA / cm<2>, and the pole plate spacing is 1-3.5 cm; and sampling at set intervals and carrying out centrifugation, wherein the time for centrifugation is 5-10 min, and the time for electrolysis is 60-180 min. The method has the advantages that the diffusion of ions in a matrix solution is good due to the intermittent power supply mode of a pulse power supply, the mass transfer effect is improved, and the concentration polarization is alleviated, thus the disadvantages of poor treatment effect and power waste caused by electrode passivation are overcome to a great extent. Meanwhile, due to a continuous treatment manner, the wastewater treatment capacity is increased, and the complexity of the electrode cleaning work after electrolysis is reduced.

Description

technical field [0001] The invention relates to a wastewater treatment method, in particular to a method for treating chromium-containing wastewater by using continuous pulse electrocoagulation technology. Background technique [0002] Chromium-containing wastewater is a heavy metal wastewater that widely exists in mining, metallurgy, metal processing, electroplating, leather, paint and other industries. Chromium ions in water mainly exist in the form of trivalent and hexavalent, of which hexavalent chromium The toxicity is 100 times stronger than that of trivalent chromium. Direct discharge without treatment or unqualified treatment will seriously pollute river water and groundwater, endanger farmland and human health, and cause great harm to the ecological environment and human survival. Chromium generally penetrates into human and animal cells in the hexavalent form first, and then reduces to trivalent chromium in the cells to form a final carcinogen. Trivalent chromium ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C02F9/06C02F101/22
Inventor 陆君李艳陆鸿飞刘玉玲蔡星伟高玉华潘龙
Owner 江苏通瑞环保科技发展股份有限公司
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