Hybrid chemical and biological process for decontaminating sludge from municipal sewage

A sludge and chemical technology, applied in the direction of chemical instruments and methods, biological water/sewage treatment, oxidation treatment of sludge, etc., can solve the problems of increased investment and long treatment time, and achieve short residence time, low chemical cost, good control effect

Inactive Publication Date: 2002-09-04
加拿大国家科学研究院
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the processing time is still long (1.5-2 days) compared to the chemical method (0.02-0.25 days), which leads to an increase in the initial investment, such as the purchase and operation cost of the bioreactor, especially in terms of electricity consumption

Method used

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  • Hybrid chemical and biological process for decontaminating sludge from municipal sewage
  • Hybrid chemical and biological process for decontaminating sludge from municipal sewage
  • Hybrid chemical and biological process for decontaminating sludge from municipal sewage

Examples

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Effect test

Embodiment 1

[0066] The method of the present invention was tested using ferric chloride to assist in the treatment of physico-chemical sludge from a municipal sewage process. 47 trials were performed in batch form. 143m was treated by adding sulfuric acid as an oxidizing agent and hydrogen peroxide directly to the sludge through a leaching step 3 The sludge with a total average solid content of 29.3g / L. During these tests the pH was varied between 2.0-2.6 while the redox potential was adjusted to 400-500 mV and the leaching time was varied between 1-4 hours.

[0067] The results show that it is possible to reduce the levels of toxic metals in the sludge to meet the criteria for utilization of these biota. For all sludges produced in the tests, the average contents of the following elements per kg of dewatered and clarified sludge were as follows:

[0068] Cd 5.83±2.93mg / kg Cr 127±36mg / kg

[0069] Cu 273±56mg / kg Ni 29.5±9.7mg / kg

[0070] Pb 98.6±20.4mg / kg Zn 285±115mg / kg

[0071] It ...

Embodiment 2

[0078] The purification and stabilization method of the present invention was tested on the treatment of biological sludge from municipal sewage treatment. In these studies, a total of 4 tests were performed as a batch operation. Treatment of 16m by direct addition of sulfuric acid and ferric chloride as an oxidant to the sludge through a leaching step 3 In sludge with a total average solid content of 20.5g / L. During these tests the pH was varied between 2.0-2.5 while the redox potential was adjusted to 400-490 mV and the leaching time was varied between 1-4 hours.

[0079] For these tests, the metal dissolution rates measured on a metal-in-solution basis in the dewatered filtrate of clarified sludge are given below:

[0080] Cd 90.8±11.4% Cr 63.0±2.4%

[0081] Ni 84.0±11.7% Pb 30.5±7.6%

[0082] Zn 91.8±4.5%

[0083]After 1 hour of treatment under the above leaching conditions, the sludge was tested for reduction in the concentration of total E. coli, faecal E. coli and ...

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Abstract

The invention relates to a hybrid biological and chemical method for decontaminating sludge containing heavy metals and pathogenic microorganisms, consisting of the following steps: the sludge is mixed with an acidic leaching solution in order to acidify the sludge with a pH which is low enough to solubilize the majority of the heavy metals and to destroy most of the pathogenic microorganisms but which is also high enough to minimize the solubilization of fertilizing elements; oxidation-reduction of more than +400 mv is maintained, liquid-solid separation occurs in order to obtain a solid fraction comprising decontaminated acidic sludge and a liquid fraction comprising heavy metals which are dissolved in a leaching solution; the sludge is neutralized: and neturalized decontaminated sludge is recovered, whereby the fertilizing elements contained therein, i.e. carbon, nitrogen and phosphorus, remain substantially unchanged in relation to the initially contaminated sludge.

Description

field of invention [0001] The invention relates to a method for purifying sewage sludge, for example sludge from municipal sewage. This technology allows to significantly reduce the content of toxic metals in the sludge, and in the process, preserve its nutritional properties, destroy the pathogenic bacteria contained in it and significantly reduce the generation of odor during and after treatment. Sludges from wastewater that can be treated by the method of the present invention include primary and secondary sludge, aerobic or anaerobic digested sludge, sludge from ponds or anaerobic treatment tanks. Background of the invention [0002] The annual world production of sewage sludge from domestic water treatment is estimated to be close to 50 million metric tons on a dry weight basis. The most common removal methods for the disposal of these sludges are incineration, sanitary landfill and agricultural dispersion. The cost of treating and disposing of sludge using these trad...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C12N1/20C02F1/52C02F1/66C02F1/72C02F1/78C02F3/34C02F9/00C02F11/00C02F11/06C02F11/14
CPCC02F1/72C02F1/66C02F1/78C02F1/52C02F11/004C02F2101/20C02F9/00C02F3/345C02F2303/04C02F1/722
Inventor 琼-弗朗索瓦·布莱纳塔莉·默尼耶琼-路易斯·萨斯塞维尔拉杰什瓦尔·D·佳盖居伊·默西埃法蒂玛·哈姆
Owner 加拿大国家科学研究院
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