Method for circularly extracting protein and humus from residual sludge after dehydration by combining ultrasonic method with acid process

Abstract

The invention provides a method for circularly extracting protein and humus from residual sludge after dehydration by combining an ultrasonic method with an acid process and relates to a method for extracting the protein and humus from the residual sludge. The method disclosed by the invention can be used for solving the technical problems that the existing sludge recycling method only can extract single substance from the sludge, maximum use of resource can not be realized and biodegradability is poor. The method disclosed by the invention comprises the following steps: firstly, ultrasonically cracking the dehydrated residual sludge which is produced by a municipal sewage treatment plant under the acidic condition; secondly, standing and settling for promoting precipitation of protein; thirdly, centrifuging and extracting the protein; fourthly, filtering and separating the humus, and recycling filtrate. The method has the advantages that the protein and humus can be extracted at the same time, extraction is complete, biodegradability of the sludge left after extraction is increased to 75.7% from 40.2%, and the method can be applied to the field of resource recycling treatment of municipal sludge.

Description

technical field

[0001] The invention relates to a method for extracting protein and humus from excess sludge, belonging to the field of solid waste treatment and resource utilization. Background technique

[0002] Municipal sludge is a by-product of sewage treatment, mainly from the operation of primary settling tanks, secondary settling tanks and other process links. With the vigorous development of my country's sewage treatment business, more and more municipal sludge is produced. The sludge produced by sewage treatment plants contains a large amount of harmful substances such as heavy metals, diseased insect eggs, and parasites, but it also contains a large amount of Organic matter, N, P and other nutrients. Therefore, the current domestic and foreign sludge treatment and disposal processes have put forward the overall requirements of stabilization, reduction, resource utilization, and energy utilization.

[0003] The composition of municipal sludge is mainly organic mat...

Examples

specific Embodiment approach 1

[0029] Embodiment 1: A method of utilizing ultrasonic method and acid method to extract protein and humus in dewatered excess sludge in this embodiment is carried out according to the following steps:

[0030] 1. Ultrasonic cracking of the dehydrated excess sludge of urban sewage treatment plants under acidic conditions: adjust the excess sludge of urban sewage treatment plants to a pH of 1 to 3 with sulfuric acid at a concentration of 2mol / L, at a frequency of 20KHz, power density Crumble in a 1-2W / mL ultrasonic breaker for 10-30 minutes, then pass through a 100-mesh sieve to remove solid particulate matter on the sieve to obtain a lysate;

[0031] 2. Static precipitation promotes protein precipitation: the lysate is statically settled at room temperature for 30-60 minutes, so that the cracked protein is precipitated under acidic conditions;

[0032] 3. Extract protein by centrifugation: centrifuge the lysed solution after settling in a centrifuge at a temperature of 4-30°C a...

specific Embodiment approach 2

[0036] Embodiment 2: The difference between this embodiment and Embodiment 1 is that the pH in step 1 is 2. Others are the same as in the first embodiment.

[0037]In this embodiment, 2mol / L sulfuric acid is used to adjust to different pH values, the pH is 1, 2, and 3, and then ultrasonically treated, and the lysate is taken for detection. When the pH is 1, 2, and 3, the protein recovery rate is 75 %, but when the pH of the solution is equal to 3, the recovery rate of humic substances is only 57.8%. Considering the economic benefit and crushing effect, pH=2 is the optimum pH value.

specific Embodiment approach 3

[0038] Embodiment 3: This embodiment differs from Embodiment 1 or Embodiment 2 in that the power density in step 1 is 1.5 W / mL. Others are the same as in the first or second embodiment.

[0039] The sludge of this embodiment is ultrasonically treated under different ultrasonic power densities and different pHs, and the content of dissolved organic carbon (DOC) in the lysate is measured after ultrasonication. The results show that: under the same pH value, when the ultrasonic power When the density increased from 0W / mL to 1.5W / mL, the concentration of DOC in the lysate gradually increased, and then with the increase of ultrasonic power density, the dissolution and removal of DOC was gentle, so when the ultrasonic power density was 1.5W / mL Works best.

technical field

[0001] The invention relates to a method for extracting protein and humus from excess sludge, belonging to the field of solid waste treatment and resource utilization. Background technique

[0002] Municipal sludge is a by-product of sewage treatment, mainly from the operation of primary settling tanks, secondary settling tanks and other process links. With the vigorous development of my country's sewage treatment business, more and more municipal sludge is produced. The sludge produced by sewage treatment plants contains a large amount of harmful substances such as heavy metals, diseased insect eggs, and parasites, but it also contains a large amount of Organic matter, N, P and other nutrients. Therefore, the current domestic and foreign sludge treatment and disposal processes have put forward the overall requirements of stabilization, reduction, resource utilization, and energy utilization.

[0003] The composition of municipal sludge is mainly organic mat...

Examples

specific Embodiment approach 1

[0029] Embodiment 1: A method of utilizing ultrasonic method and acid method to extract protein and humus in dewatered excess sludge in this embodiment is carried out according to the following steps:

[0030] 1. Ultrasonic cracking of the dehydrated excess sludge of urban sewage treatment plants under acidic conditions: adjust the excess sludge of urban sewage treatment plants to a pH of 1 to 3 with sulfuric acid at a concentration of 2mol / L, at a frequency of 20KHz, power density Crumble in a 1-2W / mL ultrasonic breaker for 10-30 minutes, then pass through a 100-mesh sieve to remove solid particulate matter on the sieve to obtain a lysate;

[0031] 2. Static precipitation promotes protein precipitation: the lysate is statically settled at room temperature for 30-60 minutes, so that the cracked protein is precipitated under acidic conditions;

[0032] 3. Extract protein by centrifugation: centrifuge the lysed solution after settling in a centrifuge at a temperature of 4-30°C a...

specific Embodiment approach 2

[0036] Embodiment 2: The difference between this embodiment and Embodiment 1 is that the pH in step 1 is 2. Others are the same as in the first embodiment.

[0037]In this embodiment, 2mol / L sulfuric acid is used to adjust to different pH values, the pH is 1, 2, and 3, and then ultrasonically treated, and the lysate is taken for detection. When the pH is 1, 2, and 3, the protein recovery rate is 75 %, but when the pH of the solution is equal to 3, the recovery rate of humic substances is only 57.8%. Considering the economic benefit and crushing effect, pH=2 is the optimum pH value.

specific Embodiment approach 3

[0038] Embodiment 3: This embodiment differs from Embodiment 1 or Embodiment 2 in that the power density in step 1 is 1.5 W / mL. Others are the same as in the first or second embodiment.

[0039] The sludge of this embodiment is ultrasonically treated under different ultrasonic power densities and different pHs, and the content of dissolved organic carbon (DOC) in the lysate is measured after ultrasonication. The results show that: under the same pH value, when the ultrasonic power When the density increased from 0W / mL to 1.5W / mL, the concentration of DOC in the lysate gradually increased, and then with the increase of ultrasonic power density, the dissolution and removal of DOC was gentle, so when the ultrasonic power density was 1.5W / mL Works best.

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