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Sludge treatment method for improving methane yield of excess sludge by backflow of digestion solution

A technology for excess sludge and sludge treatment, applied in water/sludge/sewage treatment, biological sludge treatment, chemical instruments and methods, etc., can solve problems such as reducing value, and achieve the effect of simple and efficient pretreatment methods

Inactive Publication Date: 2021-06-29
HUNAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] Many previous studies have improved methane production by optimizing sludge pretreatment methods, e.g., heat, alkali, ultrasound, and although these techniques can significantly increase methane production, they require additional inputs of energy or chemicals, which reduce its value

Method used

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  • Sludge treatment method for improving methane yield of excess sludge by backflow of digestion solution
  • Sludge treatment method for improving methane yield of excess sludge by backflow of digestion solution

Examples

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Effect test

Embodiment 1

[0016] (1) After the residual sludge of an urban sewage treatment plant is concentrated by gravity, the sludge is used as the digestion substrate, and the digested sludge in the anaerobic reactor is used as the inoculation sludge.

[0017] (2) Reflux 15% of the digestive solution into the sludge in (1), after alkali treatment (pH 9.5) for 24 hours, adjust the pH=7.0±0.2, add the inoculation sludge according to the mass ratio of 0.3, mix well, and mix the sludge Put the mud into the anaerobic digestion reactor, and put it in a shaker at 35°C and 120r / min to digest for 25 days after being aerated with nitrogen.

[0018] (3) Experimental results show that the present invention has an obvious effect on promoting the output of excess sludge methane, and the cumulative output of methane in 25 days can reach 260.85mL / g VSS, which is 1.48 times that of the unrefluxed digestate (see Figure II ).

Embodiment 2

[0020] (1) After the residual sludge of an urban sewage treatment plant is concentrated by gravity, the sludge is used as the digestion substrate, and the digested sludge in the anaerobic reactor is used as the inoculation sludge.

[0021] (2) Reflux 20% of the digestive juice into the sludge in (1), after alkali treatment (pH 9.5) for 24 hours, adjust the pH=7.0±0.2, add the inoculation sludge according to the mass ratio of 0.3, mix well, and mix the sludge Put the mud into the anaerobic digestion reactor, and put it in a shaker at 35°C and 120r / min to digest for 25 days after being aerated with nitrogen.

[0022] (3) Experimental results show that the present invention has an obvious effect on promoting the output of residual sludge methane, and the cumulative output of methane in 25 days can reach 278.75mL / g VSS, which is 1.58 times that of the unrefluxed digestate (see Figure II ).

Embodiment 3

[0024] (1) After the residual sludge of an urban sewage treatment plant is concentrated by gravity, the sludge is used as the digestion substrate, and the digested sludge in the anaerobic reactor is used as the inoculation sludge.

[0025] (2) Reflux 25% of the digestive juice in the sludge in (1), after alkali treatment (pH 9.5) for 24 hours, adjust the pH=7.0±0.2, add the inoculation sludge according to the mass ratio of 0.3, mix well, and mix the sludge Put the mud into an anaerobic digestion reactor, adjust the pH=7.0±0.2, and put it in a shaker at 35°C and 120r / min for 25 days to digest after nitrogen exposure.

[0026] (3) Experimental results show that the present invention has an obvious effect on promoting the output of excess sludge methane, and the cumulative output of methane in 25 days can reach 240.17mL / g VSS, which is 1.36 times that of the unrefluxed digestate (see Figure II ).

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Abstract

The invention provides a sludge treatment method for increasing the methane yield of excess sludge by backflow of digestion solution. The method specifically comprises the following steps: by taking excess sludge in a secondary sedimentation tank of a sewage treatment plant after gravity concentration as a digestion substrate, enabling a digestion solution with a certain volume ratio to flow back into a digestion system, carrying out alkali pretreatment, adding sludge rich in methane bacteria as an inoculant, and carrying out anaerobic digestion. Experiments show that the method can improve the methane yield of anaerobic digestion of the excess sludge, and the maximum yield can reach 282.5+ / -11.1 mL / g VSS. By controlling the backflow ratio, the yield of methane in anaerobic digestion of the low-organic-matter sludge can be increased, the purpose of sludge recycling can be achieved, and resource utilization of the organic-matter sludge is promoted.

Description

technical field [0001] The invention relates to a method for increasing the methane output of excess sludge anaerobic digestion, and relates to the field of resource utilization of solid waste. [0002] technical background [0003] As the main by-product of the biological wastewater treatment process, more and more waste activated sludge is produced, and its treatment and disposal has become a serious challenge for wastewater treatment plants today. If there is no effective treatment method, sludge can easily cause secondary pollution to the ecosystem, thus threatening environmental safety and public health. There are many methods for sludge treatment, including biological and chemical methods, among which the anaerobic digestion of sludge has attracted widespread attention, which saves fossil fuels, reduces sludge reuse, and realizes energy utilization of biogas. Activated sludge method is currently the most widely used sewage treatment method in sewage treatment plants. T...

Claims

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Application Information

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IPC IPC(8): C02F11/04
CPCC02F11/04C02F2209/06Y02E50/30
Inventor 何丹丹肖珺王冬波
Owner HUNAN UNIV