Method for removing heavy metal in urban sludge by employing electric repairing technique

A technology for municipal sludge and electric remediation, applied in sludge treatment, chemical instruments and methods, water/sludge/sewage treatment, etc., can solve technical complexity, lack of enhancement technology, and insignificant removal of heavy metals from sludge, etc. problem, to achieve the effect of low treatment cost, enhanced repair effect, good biodegradability

Inactive Publication Date: 2008-09-17
TONGJI UNIV
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  • Abstract
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Problems solved by technology

[0004] However, due to the complexity of the technology itself, especially the lack of necessary enhancement technology,

Method used

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  • Method for removing heavy metal in urban sludge by employing electric repairing technique

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] The sludge used in the experiment was taken from Shanghai Quyang Wastewater Treatment Plant, and the nature of the sewage is domestic sewage. Basic characteristics of sludge: pH 6.52; Cu 212mg.kg -1 ;Zn 1487mg.kg -1 ;Cr 25.7mg.kg -1 ;Pb78.2mg.kg -1 ;Ni 24.8mg.kg -1 ;Cd 16.8mg.kg -1 (The above are all based on dry matter). The electrodynamic restoration device used was modified and optimized on the basis of referring to the soil electric restoration device designed by the Nanjing Soil Institute of the Chinese Academy of Sciences ( figure 1 ), the bed body is made of plexiglass tube, the inner diameter is 20cm, the bed body length is 50cm, and the whole sludge bed can be filled with about 4kg sludge. Dig 15 and small holes equidistantly above the sludge bed to facilitate the measurement of the voltage drop along different stages of the bed. The electrode is made of ordinary graphite material with a diameter of 8 mm. The voltage is applied through a DC voltage stabi...

Embodiment 2

[0029] The sludge from the sewage plant and the electric restoration device used in the experiment are as in Example 1.

[0030] The test sludge was pretreated before treatment, the moisture content was 82.3%, and the sludge was treated with 0.01N HNO 3 After acidification, pH = 4.1. At the same time, in the pretreatment process, PESA solution (the molar ratio of PESA to the total amount of heavy metals in the sludge is 4:1) was also added, and the sludge was fully mixed by stirring. Put the pretreated sludge into the sludge bed and start electrokinetic treatment. By adjusting the voltage, the bed body is maintained at about 1.2V / cm, and the actual voltage gradient fluctuates between 1.21 and 1.24V / cm. As in Example 1, during operation, the pH of the cathodic electrolytic cell and the treatment pool were adjusted by 0.1 mol / L acetic acid buffer to maintain the pH value of the cathodic electrolytic cell at around 5-6.

[0031] After 15 days of running time, the sludge from th...

Embodiment 3

[0033] In order to further verify the effect of electrodynamic restoration technology on the removal of heavy metals in sludge, the present invention also takes industrial sewage treatment plant sludge with high heavy metal content as the treatment object. The industrial sludge tested was taken from Shanghai Taopu Industrial Wastewater Treatment Plant. The basic characteristics of the sludge: pH 8.07; Cu 4258mg.kg -1 ;Zn 13879mg.kg -1 ;Cr 420mg.kg -1 ;Pb 68.3mg.kg -1 ;Ni 621mg.kg -1 ;Cd 578mg.kg -1 (The above are all based on dry matter). The electric restoration device used in the experiment is as in Example 1.

[0034] The test sludge was pretreated before treatment, the water content was 84.7%, and the sludge was treated with 0.01N HNO 3 After acidification, pH = 3.9. At the same time, in the pretreatment process, a PESA solution (the molar ratio of PESA to the total amount of heavy metals in the sludge is 5:1) was also added, and the sludge was fully mixed by stirri...

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Abstract

The invention relates to a method for removing heavy metal in sludge from municipal sewage plant by using emerging electrokinetic remediation (ERT) green technology, belonging to the technology field of environmental protection. The method comprises the steps of: building an ERT device; and loading the pre-treated sludge from municipal sewage plant into a sludge bed, and performing electrokinetic treatment at a bed body voltage gradient of 1.2-1.3 V/cm while maintaining pH of electrolyte at 6-8 and employing poly epoxy succinic acid (PESA) as complexing agent for enhancing electromigration capability of heavy metal. The mean removal rate of the heavy metal is over 60% during the electrokinetic process. The Cu, Zn, Cr, Pb, Ni and Cd contents in the treated sludge completely satisfy the sludge agricultural application national standard (GB4284-84). The inventive method has the advantages of simple process, short treatment period, good treatment effect, and low treatment cost; and will take an important role in harmless and resource treatment of municipal sludge, especially industrial sludge in the future.

Description

technical field [0001] The invention belongs to the technical field of environmental protection, and relates to a method for removing heavy metals from excess sludge in urban sewage treatment plants and an enhancement technology thereof. Background technique [0002] Municipal sludge refers to the solid waste generated during the treatment of urban domestic sewage and industrial wastewater, and is a regular product of urban sewage treatment plants. In recent years, with the continuous improvement of my country's urban sewage treatment rate, the amount of sludge produced is also increasing rapidly. Municipal sludge is generally rich in available nitrogen, phosphorus, trace elements and organic matter, and is often used as fertilizer and soil conditioner. However, the content of heavy metals in sludge is generally relatively high, and it is easy to cause secondary pollution to soil, groundwater, animals and plants in the process of land use. The problem of heavy metal content...

Claims

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Application Information

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IPC IPC(8): C02F11/00
Inventor 杨长明李建华
Owner TONGJI UNIV
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