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Method for removing heavy metals from municipal residual sludge

A technology for excess sludge and heavy metals, applied in sludge treatment, chemical instruments and methods, water/sludge/sewage treatment, etc., can solve problems such as increasing the concentration of heavy metals in the cathode area, and achieve improved electrode efficiency, electrical efficiency, The effect of simplifying the structure of the device

Inactive Publication Date: 2013-01-09
NANJING RUNTRY WATER
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0012] Use vertical electrolytic cells to solve the problem of sludge agglomeration in the anode area, add super absorbent resin with polyelectrolyte properties in the cathode area to form a conductive gel phase to eliminate the resistance of the isolation layer, and increase the concentration of heavy metals in the cathode area without reverse diffusion , the method of strengthening the electric method to remove heavy metals in urban surplus sludge

Method used

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  • Method for removing heavy metals from municipal residual sludge

Examples

Experimental program
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Effect test

Embodiment 1

[0034] The sludge used in the experiment was taken from a municipal sewage treatment plant in Nanjing. The heavy metal content of the sludge was: Cu 316mg / kg; Zn 1869mg / kg; Ni65mg / kg; Cd 3.6mg / kg; Cr 98mg / kg; Pb 87mg / kg. Compared with my country's "Pollutant Control Standards in Agricultural Sludge", only the content of Cu and Zn exceeds the standard. The vertical electrolytic cell is made of a plexiglass tube with an inner diameter of 20cm. The height of the cathode area is 15cm, and the height of the sludge area is 50cm. , the circuit is connected with an ammeter and a voltmeter, and the voltage is adjustable.

[0035] The moisture content of the urban surplus sludge to be treated is 80%, and the water content is 0.01N NHO 3 Acidification, the acidity after acidification is pH4.5. First put the polyacrylic acid superabsorbent resin gel into the bottom of the vertical electrolytic tank, then fill it with sludge, turn on the power and adjust the voltage so that the average v...

Embodiment 2

[0038] The water content, acidity, heavy metal content, average voltage gradient of the electrolytic cell and the treatment device of the sludge used in the experiment are the same as those in Example 1.

[0039] After 9 days of power-on operation, the six heavy metal contents of Cu, Zn, Ni, Cd, Cr, and Pb in the discharged sludge were measured. The results showed that the heavy metal content of the treated sludge was: Cu 172mg / kg; Zn 484mg / kg; Ni 30mg / kg kg; Cd 2.1mg / kg; Cr 63mg / kg; Pb 45mg / kg. Compared with my country's "Pollutant Control Standards in Agricultural Sludge", the content of Cu and Zn both reached the standard of agricultural sludge.

Embodiment 3

[0041] The water content, acidity, heavy metal content, average voltage gradient of the electrolytic cell and the treatment device of the sludge used in the experiment are the same as those in Example 1.

[0042] After 12 days of power-on operation, the six heavy metal contents of Cu, Zn, Ni, Cd, Cr, and Pb in the discharged sludge were measured. The results showed that the heavy metal content of the treated sludge was: Cu 166mg / kg; Zn 463mg / kg; Ni 30mg / kg kg; Cd 2.0 mg / kg; Cr 63 mg / kg; Pb 43 mg / kg. Compared with my country's "Pollutant Control Standards in Agricultural Sludge", the content of Cu and Zn has reached the standard of agricultural sludge. Since the electrodynamic treatment is difficult to remove organic and residual heavy metals, the operation time should not exceed the comprehensive removal effect and economy. 12 days.

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Abstract

The invention provides a method for removing heavy metals from municipal residual sludge. The problem that the sludge is blocked in an anode region and the sludge is uneven is solved by using a vertical electrolytic tank; super absorbent resins are added into a cathode region to form conductive gel phases to eliminate the resistance of an isolation layer and increase the concentration of the heavy metals in the cathode region without reverse direction diffusion; heavy metal ions can be reduced into the zero-valent heavy metals in position to increase the electrode efficiency. The treated municipal residual sludge has the water content of 80-85% and is acidized with 0.01 N NHO3 to regulate pH to 4-5; the average voltage gradient of the electrolytic tank is 0.2-0.5 V / cm; an anode is made of graphite; a cathode is made of metals; the power-on processing time is 6-12 d; the content of Cu, Zn, Ni, Cd, Cr, Pb in the sludge before treatment and after treatment can be tested; results display the content of the heavy metals in the treated sludge accords with the pollutants control standards in agricultural sludge in our country.

Description

technical field [0001] The invention belongs to the technical field of treating excess urban sludge, and in particular relates to a vertical electrolytic cell, which solves the problems of sludge agglomeration in the anode area and uneven sludge in the electrolytic cell; The conductive resin forms a conductive gel phase to eliminate the resistance of the isolation layer, and strengthens the electrokinetic method for removing heavy metals in urban residual sludge. Background technique [0002] In the process of biochemical urban sewage treatment, a large amount of excess sludge will be produced. The ideal disposal method for these excess sludge is to use it in agriculture. However, the heavy metals in the excess sludge restrict its application in agriculture. If heavy metals cannot be removed in advance, serious pollution accidents will be caused. For this reason, my country has formulated the "Standards for the Control of Pollutants in Agricultural Sludge" (GB4284-84). There...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C02F11/00C08J3/24C08L33/02C08F120/06
Inventor 周迟骏倪国
Owner NANJING RUNTRY WATER