Method for improving the purity of methane in biogas produced by anaerobic digestion of sludge

An anaerobic digestion and biogas technology, which is applied in the field of environmental engineering, can solve the problems of low added value of biogas and low efficiency of biogas, and achieve the effects of enhancing destruction, improving acid hydrolysis, and improving methane purity

Active Publication Date: 2021-03-09
SHANGHAI JIAO TONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] Aiming at the current technical problems of low biogas recovery efficiency and low added value of biogas by anaerobic digestion of sludge, the present invention provides a method that can not only improve the efficiency of anaerobic digestion of sludge, but also improve the purity of biogas produced by anaerobic digestion of sludge

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  • Method for improving the purity of methane in biogas produced by anaerobic digestion of sludge

Examples

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Embodiment 1

[0022] This example relates to a method for improving the purity of methane in biogas produced by anaerobic digestion of sludge. The process flow is as follows figure 1 As shown, it specifically includes the following steps:

[0023] A sewage plant in Shanghai, the object is the residual sludge of the secondary sedimentation tank, the solid content of the sludge after thickening is 20g / L. In the stage of hydrolytic acidification, the dosage of calcium nitrite is 500mg N / L (that is, 2.36g Ca(NO 2 ) 2 / L), while using 6M HCl solution to gradually adjust the pH of the fermentation mixture to 6.0, and the temperature was controlled at 37±2°C. Control the residence time of the sludge to 3 days, and keep the ORP in the hydrolysis fermentation tank at -100mV. After hydrolysis to produce acid, it is transported to the adjustment tank, and the pH is adjusted back to 6.5 with 5M NaOH solution, and then transported to the anaerobic reactor. The abundance of hydrogenotrophic methanogen...

Embodiment 2

[0025] This embodiment relates to a method for improving the purity of methane in biogas produced by anaerobic digestion of sludge, which specifically includes the following steps:

[0026] For a domestic sewage plant in Shanghai, the object is the residual sludge in the secondary sedimentation tank, and the solid content of the sludge after thickening is 40g / L. The dosage of calcium nitrite is 2000mg N / L (that is, 9.43g Ca(NO 2 ) 2 / L), use 6M HCl solution to gradually adjust the pH of the fermentation mixture to 4.0, control the temperature at 37±2°C, and mix well. The sludge residence time in the hydrolysis fermentation tank is 1d, and the ORP in the hydrolysis fermentation tank is kept at -200mV. After hydrolysis to produce acid, it is transported to the adjustment tank, and the pH is adjusted back to 6.3 with 5M NaOH solution, and then transported to the anaerobic reactor. The abundance of hydrogenotrophic methanogen Methanobacterium reaches 40%. The sludge residence t...

Embodiment 3

[0028] This embodiment relates to a method for improving the purity of methane in biogas produced by anaerobic digestion of sludge, which specifically includes the following steps:

[0029] In a sewage plant in Shanghai, the object is to discharge sludge from the thickening tank. The solid content of the sludge is 30g / L, and the dosage of calcium nitrite is 1300mg N / L (ie, 6.13g Ca(NO 2 ) 2 / L), using 6M HCl solution to gradually adjust the pH of the fermentation mixture to 5.0, the temperature was controlled at 37±2°C, and the mixture was evenly mixed with continuous stirring. The sludge residence time in the hydrolysis fermentation tank is 2 days, and the ORP in the hydrolysis fermentation tank is kept at -300mV. After hydrolysis to produce acid, it is transported to the adjustment tank, and the pH is adjusted back to 6.0 with 5M NaOH solution, and then transported to the anaerobic reactor, where the abundance of hydrogenotrophic methanogen Methanobacterium reaches 50%. Th...

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Abstract

The invention provides a method for improving the purity of methane in biogas produced by anaerobic digestion of sludge, which comprises the following steps: after concentrating the organic sludge to a solid content rate of 20-40g / L, adding additives, and controlling the pH The value is 4.0-6.0, and the hydrolysis and acidification reaction is carried out at 35-39 °C; after the pH value of the hydrolysis-acidification sludge is adjusted to 6.0-6.5, the anaerobic digestion reaction is carried out to collect biogas. The present invention uses calcium nitrite as an additive, which promotes sludge lysis and hydrolysis to produce acid, greatly increases the rate of sludge anaerobic acid production, and further improves the efficiency of sludge anaerobic digestion; the addition of calcium nitrite also plays a role By sequestering carbon, it reduces the concentration of carbon dioxide in the biogas and improves the purity of methane; and adjusting the pH twice not only improves the acidic hydrolysis of sludge under the action of calcium nitrite, but also facilitates the hydrogen formation in the anaerobic methanogenesis stage. The growth of methanogens increases the potential of carbon dioxide and hydrogen to form methane, further improving the purity of methane in the biogas.

Description

technical field [0001] The invention relates to a method for improving the purity of methane in biogas produced by anaerobic digestion of sludge, and belongs to the technical field of environmental engineering. Background technique [0002] Municipal sewage plant sludge is an extremely complex heterogeneous body composed of bacterial cells, organic debris, inorganic particles, colloids, etc. Sludge contains a large amount of organic components, as well as toxic and harmful substances such as pathogenic bacteria and parasites. Therefore, before the sludge is disposed of, it usually needs to be stabilized first, so as to avoid its great harm to the environment and human health. Anaerobic digestion is a common sludge stabilization treatment technology. Anaerobic digestion of sludge can not only stabilize and reduce sludge, but also recover the energy contained in organic carbon in sludge in the form of biogas. However, the technical penetration rate of sludge anaerobic diges...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C02F11/04C02F11/06
CPCC02F11/04C02F11/06C02F2209/06Y02E50/30
Inventor 朱南文尹常凯沈雁文袁海平黄秋杰于亚梅于森
Owner SHANGHAI JIAO TONG UNIV
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