阅读说明：本技术 一种脱水污泥温和水解提取混合氨基酸的方法 (Method for extracting mixed amino acid by mild hydrolysis of dewatered sludge ) 是由 田甘沛 边博 张利民 胡修韧 于 2019-09-11 设计创作，主要内容包括：本发明公开了一种脱水污泥温和水解提取混合氨基酸的方法,温和水解包括低温热碱协同酶处理脱水污泥以获取高品质氨基酸。主要包括：利用氢氧化钠水解污泥,释放蛋白,同时加以低温辅热,节约成本且提高蛋白提取率；对获取的蛋白液进行酶处理,提取高品质混合氨基酸。本发明利用温和方法处理废弃污泥以提取氨基酸,保证了氨基酸的完整度及丰富度,同时废弃污泥代替高蛋白原料提取混合氨基酸,实现污泥减量及资源化,对解决高品质氨基酸资源短缺和环境保护具有显著的意义。(The invention discloses a method for extracting mixed amino acid from dewatered sludge by mild hydrolysis, wherein the mild hydrolysis comprises the step of treating the dewatered sludge by low-temperature thermokalite in cooperation with enzyme to obtain high-quality amino acid. The method mainly comprises the following steps: the sludge is hydrolyzed by using the sodium hydroxide, the protein is released, and meanwhile, the low-temperature auxiliary heating is carried out, so that the cost is saved and the protein extraction rate is improved; and performing enzyme treatment on the obtained protein solution to extract high-quality mixed amino acid. The invention utilizes a mild method to treat the waste sludge to extract amino acid, ensures the integrity and the abundance of the amino acid, simultaneously replaces high-protein raw materials with the waste sludge to extract mixed amino acid, realizes sludge reduction and resource utilization, and has obvious significance for solving the shortage of high-quality amino acid resources and protecting the environment.)

1. The method for extracting the mixed amino acid by mild hydrolysis of the dewatered sludge is characterized by comprising the following steps of:

(1) collecting dewatered sludge after mechanical dewatering treatment of a domestic sewage treatment plant;

(2) mixing the collected dewatered sludge with water, putting the mixture into a reaction tank, continuously stirring and adjusting the pH value to 6.5 ~ 7.5.5, and arranging a gas collection tank connected with the reaction tank to collect reaction overflow gas;

(3) providing an external heating source for the reaction tank in the step (2), adding sodium hydroxide into the reaction tank, and maintaining the sludge at the temperature of 85 ℃ and ~ 90 ℃ for hydrolysis for 4 ~ 6h under the stirring state;

(4) pumping the sludge mixed liquor obtained after the reaction in the step (3) to a centrifugal filter, and performing centrifugal separation to obtain protein hydrolysate;

(5) pumping the protein hydrolysate obtained in the step (4) into an enzyme treatment reactor, continuously stirring and adjusting the pH to 9.5 ~ 10.5.5, and arranging a gas collection tank connected with the enzyme treatment reactor to collect reaction overflow gas;

(6) when the temperature of the protein hydrolysate in the step (5) is reduced to 50 ℃ of ~ 60 ℃, providing an external heating source for the enzyme treatment reactor in the step (5), keeping the temperature in the enzyme treatment reactor at 50 ℃ of ~ 60 ℃, and preheating for 20 ~ 30 min;

(7) and (3) after the preheating is finished, adding alkaline protease into the enzyme treatment reactor in the step (6), and carrying out protein hydrolysis for 6 ~ 8h at the temperature of 50 ℃ ~ 60 ℃ under a stirring state to obtain the enzyme-treated protein.

2. The method for extracting mixed amino acids by mild hydrolysis of dewatered sludge according to claim 1, wherein in the step (1), the water content of the dewatered sludge is 75 ~ 85 wt%.

3. The method for extracting mixed amino acids by mild hydrolysis of dewatered sludge according to claim 1, wherein in the step (2), the mixing mass ratio of the dewatered sludge to water is 1:4 ~ 1: 6.

4. The method for extracting mixed amino acids by mild hydrolysis of dewatered sludge according to claim 1, wherein the input amount of sodium hydroxide in step (3) is 12 ~ 15g/kg of dewatered sludge.

5. The method for extracting mixed amino acids by mild hydrolysis of dewatered sludge according to claim 1, wherein in the step (4), the rotation speed of the centrifugal separation is 3500 ~ 4000 r/min.

6. The method for extracting mixed amino acids by mild hydrolysis of dewatered sludge according to claim 1, wherein in the step (7), the alkaline protease is bacillus licheniformis protease, the enzyme activity is 200U/mg, and the input amount is 10 ~ 15g/L protein hydrolysate.

7. The method for extracting mixed amino acids from dewatered sludge through mild hydrolysis according to claim 1, wherein in the step (2), the step (3), the step (5) and the step (7), the rotation speed of stirring is 120 ~ 180 r/min.

8. The method for extracting mixed amino acids from dehydrated sludge through mild hydrolysis according to claim 1, wherein in the step (3) and the step (6), the external heating source is electric heating, steam heating, heat transfer oil or factory waste heat.

Technical Field

The invention belongs to a sludge treatment technology, in particular to a solid waste resource utilization method, and particularly relates to a method for extracting mixed amino acid by mild hydrolysis of dewatered sludge.

Background

The sludge produced by the domestic sewage treatment plant is large in production quantity, and has the characteristics of high water content, large total amount, high protein content in the sludge, high nutritive value and the like. The sludge treatment and disposal are realized, and the realization of sludge recycling is a new direction of sludge treatment.

From the perspective of sludge recycling, the extraction of organic matters in sludge is realized in a system with the least energy consumption, and the method is an effective way for solving the problems of domestic sewage and sludge; the extracted organic matters can be further processed, high added value utilization is realized, and the economic benefit of the organic matters can be greatly improved. In recent years, sludge has been used as agricultural fertilizer and soil improvement material. The sludge often contains lower nutrients than the total fertilizer. The low mineralization rate requires high application rate to meet the complete demand of crops on nitrogen and phosphorus. The persistent organic pollutants and heavy metals present in the sludge may cause the accumulation of persistent organic pollutants and heavy metals in the improved soil, which has attracted great attention to the application of the sludge to agricultural land. The novel fertilizer based on amino acid materials and matched with other auxiliary materials, such as microelement amino acid chelate, can effectively avoid the problem. And the domestic sewage sludge organic matter can be used as a high-quality source of amino acid.

The existing sludge amino acid extraction technology mostly adopts high temperature, high pressure and strong alkali and strong acid treatment, so that the structure and the performance of amino acid are damaged to a great extent, and a novel treatment method is urgently needed to achieve the effect of ensuring the quality of the amino acid.

Disclosure of Invention

The purpose of the invention is as follows: aiming at the problems of high treatment cost, poor structure of extracted amino acid, few varieties and the like in the prior art, the application provides a method for extracting amino acid by mild hydrolysis of dewatered sludge.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows:

a method for extracting mixed amino acid by mild hydrolysis of dewatered sludge comprises the following steps:

(1) collecting dewatered sludge after mechanical dewatering treatment of a domestic sewage treatment plant;

(2) mixing the collected dewatered sludge with water, putting the mixture into a reaction tank, continuously stirring and adjusting the pH value to 6.5 ~ 7.5.5, and arranging a gas collection tank connected with the reaction tank to collect reaction overflow gas;

(3) providing an external heating source for the reaction tank in the step (2), adding sodium hydroxide into the reaction tank, and maintaining the sludge at the temperature of 85 ℃ and ~ 90 ℃ for hydrolysis for 4 ~ 6h under the stirring state;

(4) pumping the sludge mixed liquor obtained after the reaction in the step (3) to a centrifugal filter, and performing centrifugal separation to obtain protein hydrolysate;

(5) pumping the protein hydrolysate obtained in the step (4) into an enzyme treatment reactor, continuously stirring and adjusting the pH to 9.5 ~ 10.5.5, and arranging a gas collection tank connected with the enzyme treatment reactor to collect reaction overflow gas;

(6) when the temperature of the protein hydrolysate in the step (5) is reduced to 50 ℃ of ~ 60 ℃, providing an external heating source for the enzyme treatment reactor in the step (5), keeping the temperature in the enzyme treatment reactor at 50 ℃ of ~ 60 ℃, and preheating for 20 ~ 30 min;

(7) and (3) after the preheating is finished, adding alkaline protease into the enzyme treatment reactor in the step (6), and carrying out protein hydrolysis for 6 ~ 8h at the temperature of 50 ℃ ~ 60 ℃ under a stirring state to obtain the enzyme-treated protein.

Specifically, in the step (1), the water content of the dewatered sludge is 75 ~ 85 wt%.

Preferably, in the step (2), the mixing mass ratio of the dewatered sludge to the water is 1:4 ~ 1: 6.

Preferably, in the step (3), the input amount of the sodium hydroxide is 12 ~ 15g/kg of dehydrated sludge.

Preferably, in the step (4), the rotation speed of the centrifugal separation is 3500 ~ 4000 r/min.

Preferably, the alkaline protease is bacillus licheniformis protease, is serine type endoprotease, can hydrolyze peptide chains of protein molecules to generate polypeptide or amino acid, has strong capability of decomposing protein, has the enzyme activity of 200U/mg, and has the input amount of 10 ~ 15g/L protein hydrolysate.

Preferably, in the step (2), the step (3), the step (5) and the step (7), the rotation speed of the stirring is 120 ~ 180 r/min.

Preferably, in the step (3) and the step (6), the external heating source is electric heating, steam heating, heat transfer oil or factory waste heat.

The time range of the processing period of extracting amino acid is within 20 hours.

Compared with the prior art, the invention has the following advantages:

(1) the method for extracting the dehydrated sludge mixed amino acid has high amino acid content, and the extraction amount can reach more than 8g/100g of dry sludge.

(2) The method adopts low-temperature thermokalite to cooperate with enzyme treatment, so that racemization of amino acid is avoided, damage to the amino acid is effectively reduced, and follow-up high-added-value utilization such as preparation of microelement amino acid chelate and the like is facilitated.

(3) The method provided by the invention can ensure rich amino acid types by utilizing mild treatment, and 17 amino acids including 7 essential amino acids and 10 nonessential oxyacids are contained in the extracted mixed amino acid liquid.

(4) The method for extracting sludge mixed amino acid by mild hydrolysis can effectively reduce energy consumption, has the advantages of simple operation, low investment and operation cost, wide application range and the like, and has good economic benefit, environmental benefit and social benefit.

Drawings

The foregoing and/or other advantages of the invention will become further apparent from the following detailed description of the invention when taken in conjunction with the accompanying drawings.

FIG. 1 shows the types and amounts of non-essential amino acids extracted from the 3 rd batch of sample of example 1.

FIG. 2 shows the essential amino acid types and the amounts of extracted amino acids of the 3 rd lot of sample in example 1.

FIG. 3 shows the amount of mixed amino acid extractions of 6 batches of samples in example 1.

FIG. 4 shows the amount of mixed amino acid extractions of 6 batches of sample in example 2.

FIG. 5 shows the combined amino acid extractions of 6 batches of example 3.

FIG. 6 shows the type and amount of non-essential amino acids extracted from the 3 rd batch of comparative example 1.

FIG. 7 shows the essential amino acid types and the amounts of extracted amino acids in the 3 rd batch of comparative example 1.

Detailed Description

The present invention will be described in detail below to make the objects and technical advantages of the invention more apparent and to better understand the invention.