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Method for improving methane purity in sludge anaerobic digestion generated biogas

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: 2018-11-13
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 methane purity in sludge anaerobic digestion generated biogas

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Embodiment 1

[0022] This embodiment 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 remaining sludge in the secondary sedimentation tank, and the solid content of the sludge after concentration is 20g / L. During the hydrolysis and acidification stage, 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 control the temperature at 37±2°C. The sludge retention time is controlled to 3d, and the ORP in the hydrolysis fermentation tank is maintained at -100mV. After hydrolysis and acid production, it is transported to a regulating tank, and the pH is adjusted back to 6.5 with 5M NaOH solution, and then transported to an anaerobic reactor. The abundance of hydrogen-trophic me...

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] A domestic sewage plant in Shanghai, the object is the remaining sludge in the secondary sedimentation tank, and the solid content of the sludge after concentration 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 fermenter is 1d, and the ORP in the hydrolysis fermentor is maintained at -200mV. After hydrolysis and acid production, it is transported to a regulating tank, adjusted to pH 6.3 with 5M NaOH solution, and then transported to an anaerobic reactor. The abundance of the hydrogen-trophic methanogen Methanobacterium reaches 40%. The sludge retention time is 20d, the ORP in the...

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] A sewage plant in Shanghai, the object is the thickening tank sludge, the sludge solid rate is 30g / L, the dosage of calcium nitrite is 1300mg N / L (that is, 6.13g Ca(NO 2 ) 2 / L), use 6M HCl solution to gradually adjust the pH of the fermentation mixture to 5.0, control the temperature at 37±2°C, stir continuously and mix well. The retention time of the sludge in the hydrolysis fermenter is 2d, and the ORP in the hydrolysis fermenter is maintained at -300mV. After hydrolysis to produce acid, it is transported to a regulating tank, adjusted back to pH 6.0 with 5M NaOH solution, and then transported to an anaerobic reactor. The abundance of the hydrotrophic methanogen Methanobacterium reaches 50%. The sludge retention time is 30d, the ORP in the tank is -400mV, and the temperature is 37±2℃. The ...

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Abstract

The invention provides a method for improving methane purity in a sludge anaerobic digestion generated biogas. The method comprises the following steps: concentrating organic sludge till a solid content is 20-40g / L; adding an additive, and controlling a pH value to 4.0-6.0, and carrying out a hydrolytic acidification reaction at 35-39 DEG C; adjusting the pH value of the sludge after hydrolytic acidification to 6.0-6.5, carrying out an anaerobic digestion reaction, and collecting a biogas. By adopting the method, calcium nitrite is adopted as the additive, so that sludge lysis and hydrolysis acidification can be improved, the anaerobic acid generation velocity of the sludge is greatly increased, furthermore, the sludge anaerobic digestion efficiency is improved; due to the addition of thecalcium nitrite, a function of blocking carbon is also achieved, the concentration of carbon dioxide in the biogas is also reduced, and the purity of methane is improved; as the pH value is adjusted twice, both acidic hydrolysis of the sludge under the action of the calcium nitrite is improved, and growth of hydrogen type methanogens in an anaerobic methanogenesis period is facilitated, the potential that the carbon dioxide is in reaction with hydrogen to generate the methane is improved, and the purity of the methane in the biogas is further improved.

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, and colloids. The sludge contains a lot of organic components, and also contains a lot of pathogenic bacteria, parasites and other toxic and harmful substances. Therefore, the sludge usually needs to be stabilized before it is disposed of to prevent it from causing greater harm to the environment and human health. Anaerobic digestion is a common sludge stabilization treatment technology. The anaerobic digestion of sludge can not only realize the stabilization and reduction of sludge, but also recover the energy contained in the organic carbon in the sludge in the form of biogas. However, the technology p...

Claims

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Application Information

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Patent Type & Authority Applications(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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