Biomass composite defoaming agent for sewage treatment plant as well as preparation method and application of biomass composite defoaming agent

Abstract

The invention discloses a biomass composite defoaming agent for a sewage treatment plant as well as a preparation method and application of the biomass composite defoaming agent, 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 comprising amylase and protease in the hydrolytic acidification process of the kitchen waste, the preparation method is simple, the cost is low, and the prepared biomass composite defoaming agent can be directly applied to an activated sludge process biochemical treatment unit of a sewage treatment plant and can be used for treating the kitchen waste. Meanwhile, the composite defoaming agent can also be used as a carbon source to enhance the denitrification efficiency and ensure that biochemical effluent stably reaches the standard, and is an economical, efficient and environment-friendly composite defoaming agent.

Description

Technical Field

[0001] The present application belongs to the technical field of sewage treatment and disposal, and specifically relates to a biomass composite defoamer for use in sewage treatment plants, and a preparation method and application thereof. Background Art

[0002] The activated sludge process is the most widely used biological sewage treatment technology in urban sewage and industrial wastewater treatment. It mainly uses microbial communities (including bacteria, protozoa, metazoa, etc.) to decompose and remove organic pollutants in sewage. From a macroscopic process point of view, sewage and activated sludge are fully mixed in the aeration tank, and the aeration equipment provides oxygen to the tank, allowing microorganisms to perform aerobic respiration.

[0003] However, aeration will cause foam in sewage, and the foaming problem during the treatment process is very prominent, which has troubled the normal operation of sewage treatment plants. This is because the presence of foam will reduce the oxygen transmission efficiency, deteriorate the sedimentation performance of biomass, and ultimately affect the effluent quality.

[0004] Traditional defoaming methods, such as physical methods (spraying water, mechanical cleaning, manual salvage, etc.), have the characteristics of a wide range of applications, but there are problems of short timeliness and difficulty in operation; reducing the solid residence time (SRT) and setting up biological selectors are process adjustment technologies that effectively inhibit the generation of foam, but they usually conflict with the wastewater treatment target (10-20 days SRT). The new microbial regulation defoaming technology uses specific microorganisms to degrade surfactants in wastewater, or directly eliminates foam through the metabolic activities of microorganisms. This technology has the advantages of environmental friendliness and strong durability, but most of it is currently in laboratory-scale research, and its actual engineering application still faces challenges. Chemical defoaming technology is currently the most mainstream defoaming method, especially when facing complex and large amounts of foam, chemical defoamers can quickly and effectively control the generation of foam, and have strong adaptability and lasting effects. There are many types of defoamers on the market, mainly including mineral oils, polyethers and polysiloxanes, most of which are highly targeted and have unstable defoaming effects. Although foreign defoamers have excellent defoaming performance, they are expensive and difficult to apply on a large scale in China.

[0005] In the related art, for example, the Chinese invention patent with publication number CN106215468A records a high-efficiency organosilicon defoamer and its preparation method, which is mainly composed of hydroxy silicone oil, dimethyl silicone oil, white carbon black, polyether polyol, water and other components; the Chinese invention patent with publication number CN106178610A records a high-carbon alcohol emulsified defoamer composed of high-carbon alcohol, organic hydrocarbon, water-soluble alcohol, non-cationic surfactant, water and other components; the Chinese invention patent with publication number CN107497140A records 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, which leads to complex operation, high operating costs, safety risks, and may also cause secondary pollution, which is not conducive to promotion and application.

[0006] Therefore, it is of great significance to develop a defoaming agent that has a simple manufacturing process, is green, environmentally friendly, and cost-effective. Summary of the invention

[0007] 1. Problem to be solved

[0008] In response to one of the problems of existing chemical defoamers, such as the risk of secondary pollution, high cost and complex preparation process, the present application provides a biomass composite defoamer for sewage treatment plants, a preparation method and application thereof. The biomass composite defoamer is prepared by doping a high-efficiency biological composite enzyme preparation (mainly amylase and protease) during the hydrolysis and acidification process of food waste. The preparation method is simple and the cost is low. The prepared biomass composite defoamer can be directly applied to the activated sludge biochemical treatment unit of the sewage treatment plant, can efficiently defoam, and can also be used as a carbon source to enhance the denitrification efficiency and ensure that the biochemical effluent is stable and meets the standards.

[0009] 2. Technical solution

[0010] In order to solve the above problems, the technical solutions adopted in this application are as follows:

[0011] The present application provides a method for preparing a biomass composite defoamer for a sewage treatment plant, the method comprising the following steps:

[0012] crushing and pulping the food waste to obtain pulp;

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

[0014] A high-efficiency biological composite enzyme preparation containing amylase and protease activity is added to the slurry for hydrolysis and acidification, and a biomass composite defoamer is obtained after hydrolysis and acidification.

[0015] Furthermore, in the above-mentioned preparation method of a biomass composite defoamer for a sewage treatment plant, the high-efficiency biological composite enzyme preparation is derived from the Chinese invention patent with authorization announcement number CN115141818B or is prepared according to a preparation method of a biological composite enzyme preparation in the Chinese invention patent, and the preparation method comprises the following steps:

[0016] S1: A mixture of soybean meal and wheat bran was used as the culture medium, the water content of the culture medium was adjusted to 70% with phosphate buffer, and Aspergillus oryzae spore suspension was inoculated. After solid-state fermentation at 30±5℃ for 60-120h, a high-efficiency biocomposite enzyme was produced, wherein: Aspergillus oryzae was purchased from China Industrial Microbiological Culture Collection Administration Center, and the strain number was CICC 41207; the mass mixing ratio of soybean meal and wheat bran in the culture medium was 6:4; the pH range of phosphate buffer was 6.5-7.9; based on the total solid content of the culture medium, the inoculation amount of Aspergillus oryzae spore suspension was 10 5 ~10 7 cells / g;

[0017] S2: Collect the solid fermentation product in the S1 reaction system, freeze-dry or dry at medium to low temperature, grind it, and the obtained solid powder is a high-efficiency biological composite enzyme preparation.

[0018] Furthermore, in the preparation method of the above-mentioned high-efficiency biological composite enzyme preparation, the pH of the phosphate buffer is 7.2; based on the total solid content of the culture medium, the inoculation amount of the Aspergillus oryzae spore suspension is 10 5 cells / g.

[0019] Furthermore, in the above-mentioned method for preparing a biomass composite defoamer for a sewage treatment plant, the amount of the high-efficiency biocomposite enzyme preparation added is: based on the total volatile suspended solids content (VSS) of the aqueous phase (slurry), 0 to 0.5 g / g·VSS of the high-efficiency biocomposite enzyme preparation is added. Furthermore, in the above-mentioned method for preparing a biomass composite defoamer for a sewage treatment plant, the amount of the high-efficiency biocomposite enzyme preparation added is: based on the total volatile suspended solids content of the aqueous phase (slurry), the amount of the high-efficiency biocomposite enzyme preparation added is 0.2 g / g·VSS.

[0020] Furthermore, in the above-mentioned method for preparing a biomass composite defoamer for a sewage treatment plant, the total volatile suspended solids content in the water phase (slurry) is 3 to 10%. Furthermore, in the above-mentioned method for preparing a biomass composite defoamer for a sewage treatment plant, the total volatile suspended solids content in the water phase (slurry) is 5%.

[0021] Furthermore, in the above-mentioned method for preparing a biomass composite defoamer for a sewage treatment plant, the hydrolysis and acidification time is about 2 to 5 days. Furthermore, in the above-mentioned method for preparing a biomass composite defoamer for a sewage treatment plant, the hydrolysis and acidification time is 2 days.

[0022] Furthermore, in the above-mentioned method for preparing a biomass composite defoamer for a sewage treatment plant, the hydrolysis and acidification reaction temperature is controlled at 25 to 45° C. Furthermore, in the above-mentioned method for preparing a biomass composite defoamer for a sewage treatment plant, the hydrolysis and acidification reaction temperature is 35° C.

[0023] Furthermore, in the above-mentioned preparation method of a biomass composite defoamer for a sewage treatment plant, the kitchen waste is also removed before being crushed and pulped. The impurities therein are sorted out by a combination of mechanical and manual processing, including glass, metal cans, plastic bags and metal tableware.

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

[0026] Furthermore, in the above-mentioned method for preparing a biomass composite defoamer for a sewage treatment plant, the slurry heating temperature is about 60-80°C, and the heating time is 15-45 minutes. Furthermore, the above-mentioned slurry heating temperature is about 80°C, and the heating time is 30 minutes.

[0027] The present application also provides a biomass composite defoamer for a sewage treatment plant, which is prepared by the above-mentioned method for preparing a biomass composite defoamer for a sewage treatment plant.

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

[0029] Furthermore, the above application includes: adding the biomass composite defoamer to the foam liquid, and the added volume is 0.05-1% of the volume of the foam liquid.

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

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

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

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

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

[0035] 3. Beneficial effects

[0036] Compared with the prior art, the present application has the following beneficial effects:

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

[0038] (2) The present application provides a biomass composite defoamer for use in sewage treatment plants, and 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 pollution-free, and has a simple preparation process and convenient operation. It can avoid the secondary environmental pollution that may be caused by traditional chemical defoamers and is an economical, efficient and environmentally friendly defoamer.

[0039] (3) The present application provides a biomass composite defoamer for use in sewage treatment plants, and its preparation method and application. At the same concentration, compared with fatty acids such as myristic acid, palmitic acid, and stearic acid, the foam reduction efficiency is more than doubled, and has significant technical effects. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0042] Figure 3 The results of the comparison of defoaming performance of myristic acid, palmitic acid, stearic acid and biomass composite defoamer are shown in Figure 2, where: (a) is the foaming tendency and (b) is the foam reduction efficiency. DETAILED DESCRIPTION

[0043] The present application is further described below in conjunction with specific embodiments.

[0044] It should be noted that the terms such as "upper", "lower", "left", "right", "middle", etc. cited in this specification are only for the convenience of description and are not used to limit the scope of implementation. Changes or adjustments to their relative relationships should be regarded as the scope of implementation of this application without substantially changing the technical content.

[0045] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the term "and / or" used herein includes any and all combinations of one or more of the associated listed items.

[0046] If the specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. If the manufacturers of the reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0047] As used herein, the term "about" is used to provide flexibility and imprecision associated with a given term, measurement or value. The degree of flexibility for a particular variable can be easily determined by one skilled in the art.

[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" expressly includes only A, only B, only C, and combinations of each thereof.

[0049] Concentration, amount and other numerical data can be presented in range format herein.It should be understood that such range format is only used for convenience and simplicity, and should be flexibly interpreted as not only including the numerical value clearly described as range limit, but also including all single numerical values ​​or sub-ranges contained in the range, just as each numerical value and sub-range are clearly described.For example, the numerical range of about 1 to about 4.5 should be interpreted as not only including the limit value of 1 to about 4.5 clearly described, but also including single numerals (such as 2,3,4) and sub-ranges (such as 1 to 3,2 to 4, etc.).The same principle is applicable to the scope of only narrating a numerical value, such as "less than about 4.5", which should be interpreted as including all the above-mentioned values ​​and ranges.In addition, no matter how the breadth of the described range or feature is, this explanation should be applicable.

[0050] As used herein, "foaming tendency" refers to the tendency of a liquid to produce foam when subjected to specific conditions (such as stirring, aeration, temperature changes, chemical reactions, etc.).

[0051] As used herein, "foam reduction efficiency" refers to a quantitative indicator of the ability of a defoamer to eliminate foam under certain conditions. It is used to measure the effectiveness of a certain defoaming measure in reducing foam volume or inhibiting foam generation. It is usually expressed as a percentage. For example, if the foam reduction efficiency is 80%, it means that the foam volume is reduced by 80% after taking measures.

[0052] As used in this article, "fatty acid" is a class of carboxylic acid compounds composed of a hydrocarbon chain (mainly a hydrocarbon chain) and a carboxyl group (-COOH). The length and saturation of the hydrocarbon chain vary. Its content is detected according to the detection method in the "National Food Safety Standard 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 use in a sewage treatment plant and the prepared biomass composite defoamer.

[0055] A method for preparing a biomass composite defoamer for a sewage treatment plant comprises the following steps:

[0056] The collected food waste is sorted by combining mechanical and manual processing to remove inorganic impurities such as glass, metal cans, plastic bags and metal tableware. The sorted food waste is then crushed into particles ranging from 2 to 5 mm in size, and a proper 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 for 30 min, followed by three-phase separation;

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

[0059] In this embodiment, the high-efficiency biological compound enzyme preparation is a high-efficiency biological compound enzyme preparation already obtained by the applicant, which is disclosed in the Chinese invention patent with announcement number CN115141818B previously applied for and authorized by the applicant, and is the biological compound enzyme prepared under the optimal conditions in Example 1 of the authorized patent.

[0060] The prepared composite defoamer is Figure 1 As shown, it is a yellow opaque liquid. After testing, its fatty acid content is about 1g / L.

[0061] Example 2

[0062] This example provides an evaluation of the defoaming performance of a biomass composite defoamer used in a sewage treatment plant.

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

[0064] The defoaming performance evaluation experiment of biomass composite defoamer includes the following:

[0065] The foam was obtained by multi-point sampling in an aerobic tank (±0.1 m from the water surface) of an activated sludge process in a food waste treatment plant in Chongqing, and was left to stand for 30 min before use to ensure that it was completely converted into foam liquid.

[0066] 0.05-1% (volume ratio) of biomass composite defoamer was added to 100 mL of foam liquid, and the mixture was stirred for 1 min. Meanwhile, the control group was set up without adding composite defoamer. The defoaming performance was measured.

[0067] Defoaming performance evaluation method:

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

[0069] The defoaming performance is defined by two parameters, namely the foaming tendency (calculated as formula (1)) and the foam reduction efficiency (calculated as formula (2)).

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

[0071]

[0072] Result analysis:

[0073] The results are as follows Figure 2 As shown,

[0074] Figure 2 (a) shows the test results of the foaming tendency. It can be seen that the biomass composite defoamer in the present 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 adding the defoamer (0.171mL-foam / mL·air-min), its foaming tendency is reduced by 37.4% (0.107mL-foam / mL·air-min);

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

[0076] The above results show that the biomass composite defoamer has excellent defoaming performance and can maintain high-efficiency defoaming effect within a wide dosage range.

[0077] Example 3

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

[0079] Referring to Example 2, 4 treatment groups and a control group were set up.

[0080] Treatment group 1: 1% (volume ratio) of biomass composite defoamer was added to 100 mL of foam liquid.

[0081] Treatment group 2: Myristic acid was added to 100 mL of foam solution, and the concentration in the foam solution was about 10 mg / L.

[0082] Treatment group 3: Palmitic acid was added to 100 mL of foam solution, and the concentration in the foam solution was about 10 mg / L.

[0083] Treatment group 4: Stearic acid was added to 100 mL of foam solution, and the concentration in the foam solution was about 10 mg / L.

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

[0085] The above mixed solution was stirred for 1 min and then its defoaming performance was measured.

[0086] Result analysis:

[0087] The results are as follows Figure 3 As shown,

[0088] The addition of myristic acid, palmitic acid and stearic acid alone can also effectively inhibit foaming to a certain extent, with the corresponding foaming tendency and foam reduction efficiency being 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 inhibit foaming. The foaming tendency and foam reduction efficiency are 0mL-foam / mL·air-min and 100%, respectively.

Claims

1. A method for preparing a biomass composite defoamer for a sewage treatment plant, characterized in that: The method comprises the following steps: crushing and pulping the food waste to obtain pulp; The slurry is heated and boiled, and then three-phase separation is performed to obtain an aqueous slurry; A high-efficiency biological composite enzyme preparation containing amylase and protease activity is added to the slurry for hydrolysis and acidification, and a biomass composite defoamer is obtained after hydrolysis and acidification.

2. The method for preparing a biomass composite defoamer for a sewage treatment plant according to claim 1, characterized in that: The preparation method of the high-efficiency biological composite enzyme preparation comprises the following steps: S1: A mixture of soybean meal and wheat bran was used as the culture medium, the water content of the culture medium was adjusted to 70% with phosphate buffer, and Aspergillus oryzae spore suspension was inoculated. After solid-state fermentation at 30±5℃ for 60-120h, a high-efficiency biocomposite enzyme was produced, wherein: Aspergillus oryzae was purchased from China Industrial Microbiological Culture Collection Administration Center, and the strain number was CICC 41207; the mass mixing ratio of soybean meal and wheat bran in the culture medium was 6:4; the pH range of phosphate buffer was 6.5-7.9; based on the total solid content of the culture medium, the inoculation amount of Aspergillus oryzae spore suspension was 10 5 ~10 7 cells / g; S2: Collect the solid fermentation product in the S1 reaction system, freeze-dry or dry at medium to low temperature, grind it, and the obtained solid powder is a high-efficiency biological composite enzyme preparation.

3. The method for preparing a biomass composite defoamer for a sewage treatment plant according to claim 1 or 2, characterized in that: The addition amount of the high-efficiency biological composite enzyme preparation is: based on the total volatile suspended solid content of the slurry, 0 to 0.5 g / g·VSS of the high-efficiency biological composite enzyme preparation is added.

4. The method for preparing a biomass composite defoamer for a sewage treatment plant according to claim 3, characterized in that: The hydrolysis and acidification time is about 2 to 5 days; the hydrolysis and acidification reaction temperature is controlled at 25 to 45°C.

5. The method for preparing a biomass composite defoamer for a sewage treatment plant according to claim 4, characterized in that: During the crushing and pulping process, a proper amount of water is added to form a slurry, and the solid-liquid ratio is controlled at 1:5 to 1:

10.

6. The method for preparing a biomass composite defoamer for a sewage treatment plant according to claim 5, characterized in that: The slurry heating temperature is about 60-80°C, and the heating time is 15-45 minutes.

7. A biomass composite defoamer for a sewage treatment plant, characterized in that: The biomass composite defoamer is prepared by the preparation method of a biomass composite defoamer for a sewage treatment plant as described in any one of claims 1-6.

8. Use of the biomass composite defoamer for sewage treatment plants according to claim 7 and / or the preparation method of the biomass composite defoamer for sewage treatment plants according to any one of claims 1 to 6 in sewage treatment.

9. The use according to claim 8, characterized in that: The application comprises: adding the biomass composite defoamer into the foam liquid, and the added volume is 0.05-1% of the volume of the foam liquid.

10. The use according to claim 9, characterized in that: The foam liquid includes: wastewater in an activated sludge biochemical treatment unit.

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