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Combined pretreatment method for enhancing excess sludge anaerobic fermentation to produce short-chain volatile fatty acid

A volatile fatty acid, anaerobic fermentation technology, applied in the field of ultrasonic and free ammonia joint pretreatment of excess sludge to produce short-chain volatile fatty acids, can solve the problem of weak inhibition, limited ability to degrade organic matter, unfavorable short-chain volatile fatty acids Accumulation and other issues, to achieve the effect of resource utilization and recycling

Inactive Publication Date: 2018-11-06
HUNAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Ultrasonic cracking technology has the advantages of no pollution, high energy density, and fast decomposition speed, but its ability to degrade organic matter is limited, and more than 70% of organic matter cannot be degraded
Ultrasonic pretreatment does not strongly inhibit the methanogenic process, and methanogenic bacteria will consume a large amount of short-chain volatile fatty acids, which is not conducive to the accumulation of short-chain volatile fatty acids

Method used

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  • Combined pretreatment method for enhancing excess sludge anaerobic fermentation to produce short-chain volatile fatty acid
  • Combined pretreatment method for enhancing excess sludge anaerobic fermentation to produce short-chain volatile fatty acid
  • Combined pretreatment method for enhancing excess sludge anaerobic fermentation to produce short-chain volatile fatty acid

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Effect test

Embodiment 1

[0026] First, the residual sludge in the secondary sedimentation tank of the sewage treatment plant is concentrated, and the sludge is used as the fermentation substrate. The processing steps are as follows:

[0027] Step 1: Ultrasonic pretreatment, the ultrasonic sound energy density is 2w / ml, and the ultrasonic time is 15min;

[0028] Step 2: Free ammonia pretreatment, add a certain amount of 4mol / L ammonium chloride solution to the sludge, so that the initial ammonia nitrogen concentration in the remaining sludge is 113.7mg / L, use 4mol / L NaOH solution and 4mol / L 1 L of HCl solution adjusted the pH of the remaining sludge to 9, and maintained it for 48 hours, during which the temperature was controlled at 25 ± 0.1 °C (under this condition, the initial free ammonia concentration was 50 mg NH 3 -N / L), the sludge mechanical stirring speed is 120rpm / min.

[0029] Step 3: On the third day of fermentation, the reactor is filled with nitrogen to drive oxygen, and the temperature ...

Embodiment 2

[0032] First, the residual sludge in the secondary sedimentation tank of the sewage treatment plant is concentrated, and the sludge is used as the fermentation substrate. The processing steps are as follows:

[0033] Step 1: Ultrasonic pretreatment, the ultrasonic sound energy density is 2w / ml, and the ultrasonic time is 15min;

[0034] Step 2: Free ammonia pretreatment, add a certain amount of 4mol / L ammonium chloride solution to the sludge, so that the initial ammonia nitrogen concentration in the remaining sludge is 227.4mg / L, use 4mol / L NaOH solution and 4mol / L 1 L of HCl solution adjusted the pH of the remaining sludge to 9, and maintained it for 48 hours, during which the temperature was controlled at 25 ± 0.1 ° C (under this condition, the initial free ammonia concentration was 100 mg NH 3 -N / L), the sludge mechanical stirring speed is 120rpm / min.

[0035] Step 3: On the third day of fermentation, the reactor is filled with nitrogen to drive oxygen, and the temperatur...

Embodiment 3

[0038] First, the residual sludge in the secondary sedimentation tank of the sewage treatment plant is concentrated, and the sludge is used as the fermentation substrate. The processing steps are as follows:

[0039] Step 1: Ultrasonic pretreatment, the ultrasonic sound energy density is 2w / ml, and the ultrasonic time is 15min;

[0040] Step 2: Free ammonia pretreatment, add a certain amount of 4mol / L ammonium chloride solution to the sludge, so that the initial ammonia nitrogen concentration in the remaining sludge is 341mg / L, use 4mol / L NaOH solution and 4mol / L HCl solution to adjust the pH of the remaining sludge to 9, and maintain it for 48h, during which the temperature is controlled at 25±0.1°C (under this condition, the initial free ammonia concentration is 150mg NH 3 -N / L), the sludge mechanical stirring speed is 120rpm / min.

[0041] Step 3: On the third day of fermentation, the reactor is filled with nitrogen to drive oxygen, and the temperature is controlled at 25±...

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Abstract

The invention belongs to the technical field of solid waste treatment and specifically relates to a combined pretreatment method for enhancing excess sludge anaerobic fermentation to produce short-chain volatile fatty acid. The combined pretreatment method for producing the short-chain volatile fatty acid comprises the following steps: utilizing excess sludge in a secondary sedimentation tank of asewage treatment plant as a fermentation substrate after gravity settling, ultrasonically treating the appropriate volume of sludge, adding certain ammonium chloride solution into the ultrasonically-treated sludge, adjusting pH, controlling temperature and performing free ammonia pretreatment. After pretreatment is finished, anaerobic fermentation is performed to produce the short-chain volatilefatty acid; the maximum accumulation amount of the volatile fatty acid is 255.4mg COD / g VSS, and the optimal reaction time is the sixth day of total time. Based on resourcefully utilizing sludge and reducing environmental pollution, according to the combined pretreatment method disclosed by the invention, a content of the short-chain volatile fatty acid is improved and the optimal reaction time isshortened. The combined pretreatment method disclosed by the invention has the advantages of high product yield, short reaction time, simple operation method, operation stability, energy conservation, consumption reduction and the like.

Description

technical field [0001] The invention belongs to the technical field of environmental protection, and in particular relates to a method for producing short-chain volatile fatty acids through ultrasonic and free ammonia combined pretreatment of excess sludge. Background technique [0002] With the development of today's society and the acceleration of urbanization, the discharge of urban domestic sewage is increasing day by day, the total water treatment volume and treatment degree of sewage plants will continue to expand and improve, and the amount of sludge produced will also increase day by day. At present, in domestic general sewage plants, the cost of sludge treatment and disposal accounts for about 20% to 50% of the total infrastructure and operating costs. In addition to a large amount of organic matter and rich nitrogen, phosphorus and other nutrients, sewage sludge also contains toxic and harmful components such as heavy metals, pathogenic bacteria and parasites. In ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C12P7/40
CPCC12P7/40
Inventor 黄永霞王冬波徐秋翔
Owner HUNAN UNIV
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