A biomass composite defoaming agent for sewage treatment plants and a preparation method and application thereof

Abstract

The application discloses a biomass composite defoaming agent for sewage treatment plants and a preparation method and application thereof, and belongs to the technical field of water treatment and disposal. The biomass composite defoaming agent is prepared by doping an efficient biological composite enzyme preparation mainly composed of amylase and protease in a hydrolysis and acidification process of kitchen waste, and has the advantages of simple preparation method, low cost, direct application in an activated sludge method biochemical treatment unit of the sewage treatment plant, efficient defoaming, carbon source, strengthened nitrogen removal efficiency, stable and qualified biochemical effluent, and the like, and is an economical, efficient and environment-friendly composite defoaming agent.

Description

A biomass composite defoamer for wastewater treatment plants, its preparation method and application Technical Field

[0001] This application belongs to the field of wastewater treatment and disposal technology, specifically relating to a biomass composite defoamer for wastewater treatment plants, its preparation method, and its application. Background Technology

[0002] The activated sludge process is one of the most widely used biological wastewater treatment technologies for urban sewage and industrial wastewater. It mainly utilizes microbial communities (including bacteria, protozoa, metazoa, etc.) to decompose and remove organic pollutants in wastewater. From a macroscopic process perspective, wastewater and activated sludge are thoroughly mixed in an aeration tank, and the aeration equipment provides oxygen to the tank, enabling the microorganisms to carry out aerobic respiration.

[0003] However, aeration can cause foam to form in wastewater, and the foaming problem during the treatment process is quite prominent, hindering the normal operation of wastewater treatment plants. This is because the presence of foam reduces oxygen transport efficiency, deteriorates the settling performance of biomass, and ultimately affects the quality of the effluent.

[0004] Traditional defoaming methods, such as physical methods (spraying water, mechanical cleaning, manual removal, etc.), have a wide range of applications, but suffer from short-term effectiveness and high operational difficulty. Reducing solids residence time (SRT) and setting up biological selectors are effective process adjustment techniques to suppress foam generation, but they often conflict with wastewater treatment targets (10-20 days SRT). Novel microbial-controlled defoaming technologies utilize specific microorganisms to degrade surfactants in wastewater or directly eliminate foam through microbial metabolic activities. This technology has advantages such as environmental friendliness and long-lasting performance, but currently, most research is still at the laboratory level, and its practical engineering application still faces challenges. Chemical defoaming technology is currently the most mainstream defoaming method, especially when dealing with complex and large amounts of foam. Chemical defoamers can quickly and effectively control foam generation, and are highly adaptable and long-lasting. Currently, there are many types of defoamers on the market, mainly including mineral oils, polyethers, and polysiloxanes, most of which are highly targeted but have unstable defoaming effects. Although foreign defoamers have excellent defoaming performance, their high price makes large-scale application in China difficult.

[0005] In related technologies, for example, Chinese invention patent CN106215468A discloses a high-efficiency organosilicon defoamer and its preparation method, which is mainly composed of hydroxyl silicone oil, dimethyl silicone oil, silica, polyether polyol, water, and other components; Chinese invention patent CN106178610A discloses a high-carbon alcohol emulsified defoamer composed of high-carbon alcohol, organic hydrocarbon, water-soluble alcohol, non-cationic surfactant, water, and other components; Chinese invention patent CN107497140A discloses a high-efficiency defoamer containing organosiloxane, dimethyl silicone oil, molybdenum disulfide, montmorillonite powder, charcoal powder, etc. Although the defoamers proposed in the above patents have good defoaming effects, the preparation process requires high-temperature reaction or activation, and there are many raw materials, resulting in complex operation, high operating costs, safety risks, and potential secondary pollution, which is not conducive to widespread application.

[0006] Therefore, it is of great significance to develop a defoamer that is simple to manufacture and is both environmentally friendly and cost-effective. Summary of the Invention

[0007] 1. The problem to be solved

[0008] This application addresses the problems of existing chemical defoamers, such as secondary pollution risks, high costs, and complex preparation processes. It provides a biomass composite defoamer for wastewater treatment plants, its preparation method, and its application. This biomass composite defoamer is prepared by incorporating highly efficient biological composite enzyme preparations (mainly amylase and protease) during the hydrolysis and acidification process of kitchen waste. The preparation method is simple and low-cost. The prepared biomass composite defoamer can be directly applied to the activated sludge biochemical treatment unit of the wastewater treatment plant, which can effectively defoam and also serve as a carbon source to enhance denitrification efficiency and ensure stable compliance of biochemical effluent.

[0009] 2. Technical Solution

[0010] To solve the above problems, the technical solution adopted in this application is as follows:

[0011] This application provides a method for preparing a biomass composite defoamer for wastewater treatment plants, the method comprising the following steps:

[0012] Food waste is crushed and pulped to obtain pulp;

[0013] The slurry is heated and cooked, and then subjected to three-phase separation to obtain a slurry (aqueous phase);

[0014] After adding a highly efficient biological complex enzyme preparation containing amylase and protease activity to the slurry, hydrolysis and acidification are carried out to obtain a biomass complex defoamer.

[0015] Furthermore, in the above-mentioned method for preparing a biomass composite defoamer for wastewater treatment plants, the high-efficiency biocomposite enzyme preparation is derived from Chinese invention patent CN115141818B or prepared according to a method for preparing a biocomposite enzyme preparation in that Chinese invention patent. The preparation method includes the following steps:

[0016] S1: Using a mixture of soybean meal and wheat bran as the culture medium, the water content of the medium was adjusted to 70% with phosphate buffer. Aspergillus oryzae spore suspension was inoculated, and solid-state fermentation at 30±5℃ for 60–120 h produced a highly efficient bio-complex enzyme. Specifically: Aspergillus oryzae was purchased from the China Industrial Microbial Culture Collection Center (CICC 41207); the mass ratio of soybean meal to wheat bran in the culture medium was 6:4; the pH range of the phosphate buffer was 6.5–7.9; and the inoculation amount of Aspergillus oryzae spore suspension was 10g based on the total solids content of the culture medium. 5 ~10 7 cells / g;

[0017] S2: Collect the solid fermentation material from the S1 reaction system, freeze-dry or dry at medium and low temperature, grind it, and the resulting solid powder is a high-efficiency biological complex enzyme preparation.

[0018] Furthermore, in the above-mentioned method for preparing highly efficient biological complex enzyme preparations, the pH of the phosphate buffer is 7.2; and the inoculum size of Aspergillus oryzae spore suspension is 10g based on the total solids content of the culture medium. 5 cells / g.

[0019] Furthermore, in the above-mentioned method for preparing a biomass composite defoamer for wastewater treatment plants, the amount of highly efficient bio-composite enzyme preparation added is: based on the total volatile suspended solids (VSS) content of the aqueous phase (slurry), 0-0.5 g / g·VSS of highly efficient bio-composite enzyme preparation is added. Even further, in the above-mentioned method for preparing a biomass composite defoamer for wastewater treatment plants, the amount of highly efficient bio-composite enzyme preparation added is: based on the total volatile suspended solids content of the aqueous phase (slurry), the amount of highly efficient bio-composite enzyme preparation added is 0.2 g / g·VSS.

[0020] Furthermore, in the above-mentioned method for preparing a biomass composite defoamer for wastewater treatment plants, the total volatile suspended solids content in the aqueous phase (slurry) is 3-10%. Even further, in the above-mentioned method for preparing a biomass composite defoamer for wastewater treatment plants, the total volatile suspended solids content in the aqueous phase (slurry) is 5%.

[0021] Furthermore, in the above-mentioned method for preparing a biomass composite defoamer for wastewater treatment plants, the hydrolysis and acidification time is approximately 2 to 5 days. Even further, in the above-mentioned method for preparing a biomass composite defoamer for wastewater treatment plants, the hydrolysis and acidification time is 2 days.

[0022] Furthermore, in the above-mentioned method for preparing a biomass composite defoamer for wastewater treatment plants, the hydrolysis acidification reaction temperature is controlled at 25–45°C. Even further, in the above-mentioned method for preparing a biomass composite defoamer for wastewater treatment plants, the hydrolysis acidification reaction temperature is 35°C.

[0023] Furthermore, in the above-mentioned method for preparing a biomass composite defoamer for wastewater treatment plants, the process before crushing and pulping kitchen waste also includes impurity removal, which includes sorting impurities such as glass, metal cans, plastic bags, and metal tableware through a combination of mechanical and manual processing.

[0024] Furthermore, in the above-mentioned method for preparing a biomass composite defoamer for wastewater treatment plants, during the crushing and pulping process, an appropriate amount of water is added to form a slurry, and the solid-liquid ratio is controlled at 1:5 to 1:10. Even further, the solid-liquid ratio is controlled at 1:5.

[0025] Furthermore, in the above-mentioned crushing and pulping process, the kitchen waste is crushed to a particle size range of 2 to 5 millimeters.

[0026] Furthermore, in the above-mentioned method for preparing a biomass composite defoamer for wastewater treatment plants, the slurry heating temperature is approximately 60–80°C, and the heating time is 15–45 min. Even further, the slurry heating temperature is approximately 80°C, and the heating time is 30 min.

[0027] This application also provides a biomass composite defoamer for wastewater treatment plants, which is prepared by the above-described method for preparing a biomass composite defoamer for wastewater treatment plants.

[0028] This application also provides the application of the above-mentioned biomass composite defoamer for wastewater treatment plants and / or the preparation method of the above-mentioned biomass composite defoamer for wastewater treatment plants in wastewater treatment, for removing foam generated in wastewater treatment.

[0029] Furthermore, the above applications include: adding a biomass composite defoamer to the foam liquid, with the addition volume being 0.05 to 1% of the foam liquid volume.

[0030] Furthermore, the volume added is 0.25% to 1% of the volume of the foam liquid.

[0031] Furthermore, the volume added is 0.50% to 1% of the volume of the foam liquid.

[0032] Furthermore, the volume added is 0.75% to 1% of the volume of the foam liquid.

[0033] Furthermore, the volume added is 1% of the volume of the foam liquid.

[0034] Furthermore, the aforementioned foam liquid includes: wastewater from the activated sludge biochemical treatment unit, that is, biomass composite defoamer used in the activated sludge biochemical treatment unit.

[0035] 3. Beneficial effects

[0036] Compared with the prior art, the advantages of this application are as follows:

[0037] (1) This application provides a biomass composite defoamer for wastewater treatment plants, its preparation method and application. The biomass composite defoamer is prepared by adding high-efficiency biological composite enzyme preparations (mainly amylase and protease) during the hydrolysis and acidification process of kitchen waste. The preparation method is simple and low cost. The prepared composite defoamer can be directly applied to the activated sludge biochemical treatment unit of the wastewater treatment plant. It can not only effectively inhibit the generation of foam, but also serve as a carbon source to promote the efficiency of biochemical denitrification and enhance the denitrification efficiency, thereby effectively ensuring the stable compliance of the effluent quality. It is an economical, efficient and environmentally friendly composite defoamer.

[0038] (2) The biomass composite defoamer for wastewater treatment plants provided in this application, its preparation method and application, compared with mineral oil, polyether and polysiloxane defoamers, the biomass composite defoamer has the advantages of low price, easy availability and no pollution, and the preparation process is simple and easy to operate. It can avoid the secondary environmental pollution that may be caused by traditional chemical defoamers. It is an economical, efficient and environmentally friendly defoamer.

[0039] (3) The biomass composite defoamer for wastewater treatment plants provided in this application, its preparation method and application, at the same concentration, has a foam reduction efficiency that is more than doubled compared with fatty acids such as myristic acid, palmitic acid and stearic acid, and has significant technical effects. Attached Figure Description

[0040] Figure 1 shows a sample of biomass composite defoamer.

[0041] Figure 2 shows the defoaming performance evaluation results of the biomass composite defoamer, where: (a) is the foaming tendency and (b) is the foam reduction efficiency.

[0042] Figure 3 shows the comparison results of the defoaming performance of myristic acid, palmitic acid, stearic acid and biomass composite defoamer, where: (a) is the foaming tendency and (b) is the foam reduction efficiency. Detailed Implementation

[0043] The present application will be further described below with reference to specific embodiments.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] As used in this article, "foaming tendency" refers to the tendency of a liquid to produce foam when it is affected by specific conditions (such as stirring, aeration, temperature change, chemical reaction, etc.).

[0051] As used in this article, "foam reduction efficiency" refers to a quantitative indicator of an antifoaming agent's ability to eliminate foam under certain conditions. It is used to measure the effectiveness of a certain antifoaming method in reducing foam volume or inhibiting foam formation. It is usually expressed as a percentage; for example, if the foam reduction efficiency is 80%, it means that the foam volume was reduced by 80% after the measures were taken.

[0052] As used in this article, "fatty acid" is a class of carboxylic acid compounds composed of hydrocarbon chains (mainly hydrocarbon chains) and carboxyl groups (-COOH). The length and saturation of the hydrocarbon chains vary, and their content is detected according to the detection method in the National Food Safety Standard for Determination of Fatty Acids in Food (GB 5009.168-2016).

[0053] Example 1

[0054] This embodiment provides a method for preparing a biomass composite defoamer for wastewater treatment plants and the prepared biomass composite defoamer.

[0055] A method for preparing a biomass composite defoamer for use in wastewater treatment plants includes the following steps:

[0056] The collected kitchen waste is sorted out using a combination of mechanical and manual methods to remove inorganic impurities such as glass, metal cans, plastic bags, and metal tableware. The sorted kitchen waste is then crushed to a particle size range of 2-5 mm, and an appropriate amount of water is added to form a slurry with a solid-liquid ratio controlled at 1:5.

[0057] The slurry was heated to 80°C and held for 30 minutes, followed by three-phase separation.

[0058] Based on the total volatile suspended solids content of the separated aqueous phase (slurry), a high-efficiency biological complex enzyme preparation of 0.2 g / g·VSS was added to the slurry, and the biomass complex defoamer was obtained after hydrolysis and acidification at 35℃ for 2 days.

[0059] In this embodiment, the high-efficiency biological complex enzyme preparation is a high-efficiency biological complex enzyme preparation that the applicant has already obtained. This high-efficiency biological complex enzyme preparation is disclosed in the applicant's prior Chinese invention patent application with publication number CN115141818B, and is the biological complex enzyme prepared under the optimal conditions in Example 1 of the authorized patent.

[0060] The prepared composite defoamer, as shown in Figure 1, is a yellow, opaque liquid. Its fatty acid content is approximately 1 g / L.

[0061] Example 2

[0062] This embodiment provides an evaluation of the defoaming performance of a biomass composite defoamer used in wastewater treatment plants.

[0063] In this embodiment, the biomass composite defoamer used in the wastewater treatment plant is the biomass composite defoamer prepared in Example 1.

[0064] The defoaming performance evaluation experiments for biomass composite defoamers include the following:

[0065] The foam was obtained by sampling at multiple points in the aerobic tank (water surface ±0.1m) of the activated sludge process at a kitchen waste treatment plant in Chongqing, and was allowed to stand for 30 minutes before use to ensure that it was completely converted into foam liquid.

[0066] Add 0.05–1% (volume ratio) of biomass composite defoamer to 100 mL of foam solution, mix thoroughly and stir for 1 min. A control group was set up without added composite defoamer. Defoaming performance was then measured.

[0067] Defoaming performance evaluation method:

[0068] The foaming potential of the sample was determined by the simulated aeration method, that is: 30 mL of foam liquid was placed in a graduated cylinder (inner diameter 3.8 cm, height 30 cm), and aerated from the bottom for 10 s at a flow rate of 3 L / min through a sand core aerator (diameter 3 cm, height 4 cm), and the volume of foam produced was recorded.

[0069] Defoaming performance is defined by two parameters: foaming tendency (calculated as in formula (1)) and foam reduction efficiency (calculated as in formula (2)).

[0070] Foaming tendency = foam volume after aeration (mL) / air velocity (mL / min) Formula (1)

[0071]

[0072] Results analysis:

[0073] The results are shown in Figure 2.

[0074] Figure 2(a) shows the results of the foaming tendency test. It can be seen that the biomass composite defoamer in this application has a great inhibitory effect on foaming. Even at an addition amount of 0.05% (v / v), compared with the original foam liquid without added defoamer (0.171 mL-foam / mL·air-min), its foaming tendency is reduced by 37.4% (0.107 mL-foam / mL·air-min).

[0075] Figure 2(b) shows the foam reduction efficiency. It can be seen that increasing the dosage of biomass composite defoamer can further improve the defoaming efficiency. The foam reduction efficiency exceeds 85% at a dosage of 0.5% (v / v), and the foam completely disappears when the dosage is 1% (v / v).

[0076] The above results demonstrate that this biomass composite defoamer possesses excellent defoaming performance and can maintain a high level of defoaming efficiency over a wide dosage range.

[0077] Example 3

[0078] This embodiment provides an evaluation of the defoaming performance of the biomass composite defoamer prepared in this application compared with conventional fatty acids.

[0079] Referring to Example 2, four treatment groups and a control group were set up.

[0080] Treatment Group 1: Add 1% (by volume) of biomass composite defoamer to 100mL of foam solution.

[0081] Treatment group 2: Myristic acid was added to 100 mL of foam solution, with a concentration of approximately 10 mg / L.

[0082] Treatment group 3: Palmitic acid was added to 100 mL of foam solution, with a concentration of approximately 10 mg / L.

[0083] Treatment group 4: Stearic acid was added to 100 mL of foam solution, with a concentration of approximately 10 mg / L.

[0084] Control group: Foam stock solution without any added reagents.

[0085] After stirring the above mixture for 1 minute, its defoaming performance was measured.

[0086] Results analysis:

[0087] The results are shown in Figure 3.

[0088] Adding myristic acid, palmitic acid, and stearic acid alone can also effectively inhibit foaming to some extent, with corresponding foaming tendency and foam reduction efficiency in the range of 0.13-0.15 mL-foam / mL·air-min and 14-23%, respectively.

[0089] The biomass composite defoamer has the best defoaming performance, and can completely suppress foaming. Its foaming tendency and foam reduction efficiency are 0 mL-foam / mL·air-min and 100%, respectively.

Claims

1. A method for preparing a biomass composite defoamer for use in wastewater treatment plants, characterized in that, The method includes the following steps: crushing and pulping kitchen waste to obtain slurry; heating and cooking the slurry and then performing three-phase separation to obtain an aqueous slurry; adding a high-efficiency biological complex enzyme preparation containing amylase and protease activity to the slurry and then hydrolyzing and acidifying it to obtain a biomass complex defoamer; the hydrolysis and acidification time is 2-5 days; the hydrolysis and acidification reaction temperature is controlled at 25-45℃; the preparation method of the high-efficiency biological complex enzyme preparation includes the following steps: S1: using a mixture of soybean meal and wheat bran as a culture medium, adjusting the water content of the culture medium to 70% with phosphate buffer, inoculating with Aspergillus oryzae spore suspension, and solid-state fermenting at 30±5℃ for 60-120 h to produce a high-efficiency biological complex enzyme, wherein: Aspergillus oryzae was purchased from the China Industrial Microbial Culture Collection Center, strain number CICC. 41207; The mass ratio of soybean meal to wheat bran in the culture medium is 6:4; The pH range of the phosphate buffer is 6.5–7.9; Based on the total solids content of the culture medium, the inoculum size of Aspergillus oryzae spore suspension is 10. 5 ~10 7 cells / g; S2: Collect the solid fermentation material in the S1 reaction system, freeze-dry or dry at medium and low temperature, grind it, and the resulting solid powder is the high-efficiency biological complex enzyme preparation; The addition amount of the high-efficiency biological complex enzyme preparation is: based on the total volatile suspended solids content of the slurry, add 0.2~0.5 g / g·VSS of the high-efficiency biological complex enzyme preparation; During the crushing and pulping process, add an appropriate amount of water to form a slurry, and control the solid-liquid ratio at 1:5~1:10; The heating temperature of the slurry is 60~80℃, and the heating time is 15~45 min.

2. A biomass composite defoamer for use in wastewater treatment plants, characterized in that, It is prepared by the method described in claim 1 for preparing a biomass composite defoamer for wastewater treatment plants.

3. The application of the biomass composite defoamer for wastewater treatment plants as described in claim 2 and / or the preparation method of the biomass composite defoamer for wastewater treatment plants as described in claim 1 in wastewater treatment.

4. The application according to claim 3, characterized in that, The application includes adding a biomass composite defoamer to a foaming liquid, with the added volume being 0.05~1% of the foaming liquid volume.

5. The application according to claim 4, characterized in that, The foam liquid includes wastewater from the activated sludge biochemical treatment unit.

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