An acidified seed slurry and a method of preparing the same

Abstract

The application discloses acidified seed sludge and a preparation method thereof, and belongs to the technical field of sludge treatment. The method is to add glycine to sludge after heating the sludge to 55 DEG C, and then to carry out anaerobic fermentation treatment to obtain acidified seed sludge. The acidified seed sludge is rich in acidophilic bacteria Clostridia, and the relative abundance reaches 15-35%. The acidified seed sludge has good acid resistance and high acid production rate. When the seed sludge is inoculated into a new sludge environment, the seed sludge can rapidly react, rapidly consume extracellular polymeric substances (EPS) and polysaccharide substances in cell walls in the sludge system, reduce the content of sludge organic matters and the viscosity, and achieve the effect of rapid acid production.

Description

Technical Field

[0001] This application belongs to the field of sludge treatment technology, specifically relating to an acidified seed sludge and its preparation method. Background Technology

[0002] With the continuous advancement of urbanization and industrialization in my country, rapid population and economic growth have led to an increasingly severe water shortage situation. At the same time, the deterioration of the water environment has exacerbated this situation, with both "supply and demand" and "water quality" shortages driving a continuous increase in the total discharge of urban sewage and water treatment rates. Statistics from the Ministry of Housing and Urban-Rural Development show that as of 2021, the national urban sewage treatment volume was 71.696 billion cubic meters, of which urban sewage treatment volume was 61.19 billion cubic meters and county-level sewage treatment volume was 10.506 billion cubic meters. Sludge, as a byproduct of biological sewage treatment, is characterized by high water content and large volume. Typically, sludge production can reach 0.3% to 0.5% of the sewage treatment volume (by volume, water content 97%). Under advanced treatment conditions, sludge production can reach 1% of the sewage treatment volume, resulting in a huge volume of sludge requiring treatment and disposal. Sludge has a high organic matter content and contains a large number of pathogens and other harmful components, making its harmless treatment crucial for environmental protection.

[0003] Sludge treatment and disposal follow the principles of "reduction, stabilization, harmlessness, and resource recovery." The main treatment methods for sludge include thickening, biological stabilization, and conditioning / dewatering. The aims are to reduce water content and volume for easier transportation and disposal; and to eliminate toxic and harmful substances from the sludge to achieve harmlessness and stabilization. Sludge thickening includes gravity thickening, centrifugal thickening, and flotation thickening. Sludge biological stabilization includes aerobic composting and digestion, with digestion further divided into aerobic digestion and anaerobic digestion. Anaerobic digestion, in particular, is energy-efficient, low-consumption, and can recover organic acids or biogas energy, meeting the social needs of sustainable development and attracting increasing attention. Anaerobic digestion for acid production, as a method of harmless and resource-recovery sludge treatment, can effectively convert organic matter in sludge into organic acids for biosynthesis or as a carbon source nutrient.

[0004] Currently, the traditional method of obtaining acidified seed mud mainly involves long-term anaerobic fermentation and domestication, which is time-consuming and results in complex microbial communities in the acidified seed mud, leading to low acidification efficiency. Summary of the Invention

[0005] 1. Purpose of the invention

[0006] The purpose of this application is to provide an acidified seed sludge and its preparation method, aiming to solve one of the problems in the existing technology, such as long acclimatization period of acidified seed sludge, complex microbial community of acidified seed sludge, and low acid production efficiency.

[0007] 2. Technical Solution

[0008] To achieve the aforementioned objectives, the technical solution adopted in this application is as follows:

[0009] This application provides a method for preparing acidified seed mud, the method comprising:

[0010] Sludge was obtained, heated, and then glycine was added for anaerobic fermentation to obtain acidified seed sludge rich in the acidophilic bacteria Clostridia.

[0011] Furthermore, the relative abundance of the acidophilic bacterium Clostridia in the aforementioned acidified seed mud reached 15-35%. Even further, the relative abundance of the acidophilic bacterium Clostridia in the aforementioned acidified seed mud reached 35%.

[0012] Furthermore, the aforementioned sludge is the residual sludge directly obtained from the wastewater treatment plant.

[0013] Furthermore, the solids content of the aforementioned sludge is 2%–3%. If the solids content is below 2%, the sludge concentration is too dilute, resulting in insufficient effective components and excessive water content. If the solids content is above 3%, the solids content of the sludge in the reaction system is too high, and the organic matter cannot be fully released and decomposed during the anaerobic fermentation process. Even further, the solids content of the aforementioned sludge is 2.5%.

[0014] Furthermore, the above-mentioned sludge heating involves heating to 55°C and then adding glycine. The heating temperature of 55°C is chosen because the acidic bacteria in the sludge have the highest activity at this temperature, and the organic matter inside the sludge cells can be released.

[0015] Furthermore, the amount of glycine added is 0.1% to 0.3% of the sludge dry weight. Exogenous glycine helps promote the rapid growth and reproduction of acidophilic bacteria, making them the dominant bacteria. Below 0.1%, it has no promoting effect, while an addition exceeding 0.3% will lead to further acidification of the sludge anaerobic fermentation system, which is detrimental to the growth and reproduction of acidophilic bacteria. Even further, the amount of glycine added is 0.2% of the sludge dry weight.

[0016] Furthermore, the fermentation time for the above-mentioned anaerobic fermentation is 1-3 days, and the fermentation temperature is maintained at 55℃. If the fermentation time is less than 1 day, the sludge will not be effectively acidified, resulting in the release of intracellular substances. If the fermentation time is more than 3 days, it will further produce methane, affecting the acidification effect. Even further, the fermentation time for the above-mentioned anaerobic fermentation is 2 days.

[0017] This application also provides an acidified seed mud prepared by the above-mentioned method, wherein the relative abundance of the acidophilic bacterium Clostridia in the acidified seed mud reaches 15-35%.

[0018] Furthermore, the relative abundance of the acidophilic bacterium Clostridia in the aforementioned acidified seed mud reached 35%.

[0019] This application also provides a method for preparing the above-mentioned acidified seed mud or the application of the prepared acidified seed mud in sludge treatment.

[0020] 3. Beneficial effects

[0021] Compared with the prior art, the advantages of this application are as follows:

[0022] This application provides an acidified sludge and its preparation method, which involves adding exogenous glycine followed by high-temperature (55°C) fermentation to enrich the acidophilic bacteria Clostridia in the sludge, while avoiding contamination by other harmful bacteria, resulting in sludge dominated by Clostridia, which has high acid-producing efficiency. At the high temperature of 55°C, intracellular organic matter in the sludge is rapidly released, allowing the acidifying bacteria to multiply rapidly. Simultaneously, the introduced glycine helps to increase the reproduction rate of Clostridia, making Clostridia the dominant bacteria. The acidified seed sludge obtained through the above method is enriched with acidophilic Clostridia bacteria, with a relative abundance of 15-35%, which is significantly higher than the Clostridia bacteria content in traditional acidified sludge. This gives the acidified seed sludge good acid resistance and a high acid production rate. When the seed sludge of this application is inoculated into a new sludge environment, it can rapidly consume extracellular polymeric substances (EPS) and polysaccharides in the cell walls of the sludge system, reducing the organic matter content and viscosity of the sludge, achieving rapid acid production, and reacting quickly to better act on the sludge and improve its acid production performance. At the same time, this treatment process is simple to operate, has a short acclimatization period, and is suitable for large-scale industrial applications. Detailed Implementation

[0023] The present application will be further described below with reference to specific embodiments.

[0024] It should be noted that terms such as "upper", "lower", "left", "right", and "middle" used in this specification are only for clarity of description and are not intended to limit the scope of implementation. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered as within the scope of this application.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the term “and / or” as used herein includes any and all combinations of one or more of the associated listed items.

[0026] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0027] As used herein, the term “about” is used to provide for the flexibility and imprecision associated with a given term, measure, or value. Those skilled in the art can readily determine the degree of flexibility for a particular variable.

[0028] As used herein, the term “at least one of…” is intended to be synonymous with “one or more of…”. For example, “at least one of A, B, and C” explicitly includes only A, only B, only C, and combinations thereof.

[0029] Concentration, amount, and other numerical data may be presented in range format herein. It should be understood that such range format is used solely for convenience and brevity and should be flexibly interpreted to include not only the values ​​explicitly stated as the limits of the range, but also all individual values ​​or subranges encompassed within the range, as if each value and subrange were explicitly stated. For example, a range of values ​​from about 1 to about 4.5 should be interpreted to include not only the explicitly stated limits of 1 to 4.5, but also individual numbers (such as 2, 3, 4) and subranges (such as 1 to 3, 2 to 4, etc.). The same principle applies to ranges that describe only a single value, such as “less than about 4.5,” which should be interpreted to include all the aforementioned values ​​and ranges. Furthermore, this interpretation should apply regardless of the breadth of the range or characteristic described.

[0030] In the examples, the method for detecting the relative abundance of acidophilic bacteria Clostridia refers to “Zhang J, et al. Effects of ferric iron on the anaerobic treatment and microbial biodiversity in a coupled microbial electrolysis cell (MEC)-anaerobic reactor[J]. Water research, 2013, 47(15): 5719-5728.

[0031] Example 1

[0032] This application provides a method for preparing acidified seed mud and the prepared acidified seed mud, specifically including:

[0033] Sludge was obtained, and the solids content was adjusted to 2%. After heating to 55°C, glycine at a ratio of 0.1% of the dry weight of the sludge was added. Anaerobic fermentation was carried out at 55°C, and acidified seed sludge was obtained after 1 day of fermentation.

[0034] The relative abundance of the acidophilic bacterium Clostridia in the acidified seed mud was found to be 16%.

[0035] Example 2

[0036] This application provides a method for preparing acidified seed mud and the prepared acidified seed mud, specifically including:

[0037] Sludge was obtained, and the solids content was adjusted to 3%. After heating to 55°C, glycine at a ratio of 0.3% of the dry weight of the sludge was added. Anaerobic fermentation was carried out at 55°C, and acidified seed sludge was obtained after 3 days of fermentation.

[0038] The relative abundance of the acidophilic bacterium Clostridia in the acidified seed mud was found to be 22%.

[0039] Example 3

[0040] This application provides a method for preparing acidified seed mud and the prepared acidified seed mud, specifically including:

[0041] Sludge was obtained, and the solids content was adjusted to 2.5%. After heating to 55°C, glycine at a ratio of 0.2% of the dry weight of the sludge was added. Anaerobic fermentation was carried out at 55°C, and acidified seed sludge was obtained after 2 days of fermentation.

[0042] The relative abundance of the acidophilic bacterium Clostridia in the acidified seed mud was found to be 35%.

[0043] Example 4

[0044] This application provides a method for preparing acidified seed mud and the prepared acidified seed mud, specifically including:

[0045] Sludge was obtained, and the solids content was adjusted to 2%. After heating to 55°C, glycine at a ratio of 0.2% of the dry weight of the sludge was added. Anaerobic fermentation was carried out at 55°C, and acidified seed sludge was obtained after 3 days of fermentation.

[0046] The relative abundance of the acidophilic bacterium Clostridia in the acidified seed mud was found to be 21%.

[0047] Example 5

[0048] This application provides a method for preparing acidified seed mud and the prepared acidified seed mud, specifically including:

[0049] Sludge was obtained, and the solids content was adjusted to 3%. After heating to 55°C, glycine at a ratio of 0.2% of the dry weight of the sludge was added. Anaerobic fermentation was carried out at 55°C, and acidified seed sludge was obtained after 1 day of fermentation.

[0050] The relative abundance of the acidophilic bacterium Clostridia in the acidified seed mud was found to be 15%.

[0051] Example 6

[0052] This application provides a method for preparing acidified seed mud and the prepared acidified seed mud, specifically including:

[0053] Sludge was obtained, and the solids content was adjusted to 2.5%. After heating to 55°C, glycine at a ratio of 0.1% of the dry weight of the sludge was added. Anaerobic fermentation was carried out at 55°C, and acidified seed sludge was obtained after 2 days of fermentation.

[0054] The relative abundance of the acidophilic bacterium Clostridia in the acidified seed mud was found to be 22%.

[0055] Example 7

[0056] This application provides a method for preparing acidified seed mud and the prepared acidified seed mud, specifically including:

[0057] Sludge was obtained, and the solids content was adjusted to 2.5%. After heating to 55°C, glycine at a ratio of 0.3% of the dry weight of the sludge was added. Anaerobic fermentation was carried out at 55°C, and acidified seed sludge was obtained after 2 days of fermentation.

[0058] The relative abundance of the acidophilic bacterium Clostridia in the acidified seed mud was found to be 25%.

[0059] Example 8

[0060] This embodiment provides the application of the acidified seed sludge prepared in this application in sludge treatment, including:

[0061] The seed mud obtained according to the conditions in Examples 1-2 and 4-7 was inoculated into the residual sludge with a solid content of 2%, and the inoculation amount was 10% of the dry weight of the residual sludge. The temperature was maintained at 55°C for 48 hours for fermentation. The total organic acid (TVFA) concentration was measured at the endpoint and was between 1400 and 2700 mg / L.

[0062] Example 9

[0063] This embodiment provides the application of the acidified seed sludge prepared in this application in sludge treatment, including:

[0064] The seed mud obtained according to the conditions of Example 3 was inoculated into the residual sludge with a solid content of 2%, and the inoculation amount was 10% of the dry weight of the residual sludge. The temperature was maintained at 55°C for 48 hours for fermentation. The final test showed that the total organic acid (TVFA) concentration reached 3250 mg / L.

[0065] The relative abundance of Clostridia acidophilus in the acidified sludge obtained from Examples 1-7 was determined. The results showed that the relative abundance of Clostridia acidophilus in the obtained acidified seed sludge reached 15-35%, exhibiting high acid production rate and performance. The acidified seed sludge obtained in Example 3 had the highest relative abundance of Clostridia acidophilus, reaching 35%, corresponding to the highest acid production rate. Furthermore, under these conditions, the acclimatization period for traditional acidified seed sludge was significantly shortened compared to approximately 10 days.

Claims

1. A method for preparing acidified seed mud, characterized in that, The method includes: Sludge is obtained, heated, and then glycine is added for anaerobic fermentation to produce a product rich in acidophilic bacteria. Clostridia acidified seed mud; The sludge is heated to 55°C. The amount of glycine added is 0.1-0.3% of the dry weight of the sludge; The anaerobic fermentation time is 1 to 3 days, and the fermentation temperature is maintained at 55°C. The solids content of the sludge is 2% to 3%.

2. The method for preparing acidified seed mud according to claim 1, characterized in that, The acidophilic bacteria Clostridia The relative abundance reached 15-35%.

3. A method for preparing acidified seed mud according to claim 1 or 2, characterized in that, The sludge has a solids content of 2.5%; the amount of glycine added accounts for 0.2% of the dry weight of the sludge; and the anaerobic fermentation time is 2 days.

4. An acidified seed mud, characterized in that, The acidified seed mud is prepared by any one of the acidified seed mud preparation methods according to claims 1-3, and is rich in acidophilic bacteria. Clostridia The acidophilic bacteria Clostridia The relative abundance reached 15-35%.

5. A method for preparing acidified seed mud according to any one of claims 1-3, or the application of acidified seed mud according to claim 4 in sludge treatment.