A composite carbon source and its application

Abstract

The present invention relates to a composite carbon source and its application, and relates to the field of sewage treatment technology. The composite carbon source comprises the following components, measured by weight: 10 to 20 parts of monosaccharide, 5 to 10 parts of fucoidan, 20 to 30 parts of polyol, 5 to 10 parts of fatty acid, 1 to 5 parts of rhamnolipid, and 0.5 to 1 part of vitamin. The composite carbon source provided by the present invention is mainly composed of monosaccharide, fucoidan, polyol, fatty acid, rhamnolipid and vitamin, and can be used to supplement the carbon source nutrients of activated sludge in sewage treatment plants. It can not only effectively supplement the carbon source required for denitrification in the biochemical system, but also supplement the carbon source required for phosphorus release by polyphosphate bacteria, thereby significantly improving the removal rate of total nitrogen and total phosphorus, and ensuring that the effluent meets the discharge standards.

Description

Technical Field

[0001] The present application relates to the technical field of sewage treatment, and in particular to a composite carbon source and its application. Background Art

[0002] At present, nitrification-denitrification is the most effective and economical denitrification technology for sewage treatment plants. Denitrifying bacteria use organic carbon sources as electron donors to complete the denitrification process. However, the carbon source content in the influent of most sewage treatment plants is low, resulting in a lack of electron donors for denitrifying bacteria. Nitrates are difficult to convert into nitrogen gas for release, and external carbon sources need to be added to the sewage. Otherwise, the total nitrogen content in the effluent will easily exceed the standard.

[0003] A wide variety of external carbon sources are currently available, with methanol, sodium acetate, glucose, and starch being the most commonly used. These single carbon sources cannot meet the diverse needs of various microorganisms. Prolonged use can disrupt the microbial ecological balance and hinder the system's resilience. Therefore, providing a new, highly efficient composite carbon source, while ensuring adequate carbon source replenishment, has practical application value. Summary of the Invention

[0004] This application provides a composite carbon source and its application. This composite carbon source is primarily composed of monosaccharides, fucoidan, polyols, fatty acids, rhamnolipids, and vitamins. It can be used to supplement carbon source nutrients in activated sludge from sewage treatment plants. It effectively supplements the carbon source required for denitrification in the biochemical system and the carbon source required for phosphorus release by phosphate-accumulating bacteria, thereby significantly improving the removal rates of total nitrogen and total phosphorus, ensuring that the effluent meets discharge standards.

[0005] In a first aspect, the present application provides a composite carbon source, which comprises the following components in parts by weight:

[0006] 10-20 parts of monosaccharide, 5-10 parts of fucoidan, 20-30 parts of polyol, 5-10 parts of fatty acid, 1-5 parts of rhamnolipid and 0.5-1 part of vitamin.

[0007] Furthermore, the composite carbon source comprises the following components in parts by weight:

[0008] 18 parts of monosaccharide, 7 parts of fucoidan, 26 parts of polyol, 7 parts of fatty acid, 4 parts of rhamnolipid and 0.5 parts of vitamin.

[0009] Furthermore, the weight ratio of the monosaccharide, the fucoidan, the polyol and the fatty acid is (15-18):(6-8):(25-30):(6-8).

[0010] Furthermore, the monosaccharide is composed of glucose and fructose in a weight ratio of (20-25):1.

[0011] Furthermore, the polyol is composed of sorbitol and glycerol in a weight ratio of (10-15):1.

[0012] Furthermore, the fatty acid is composed of caprylic acid and lauric acid in a weight ratio of (5-7): (2-4).

[0013] Furthermore, the vitamin is vitamin B.

[0014] Furthermore, the preparation method of the composite carbon source comprises the following steps:

[0015] 15 to 20 parts by weight of monosaccharide, 5 to 10 parts by weight of fucoidan, and 20 to 30 parts by weight of polyol are added to 40 to 60 parts by weight of water and stirred and dissolved to obtain a first solution;

[0016] Adding 5 to 10 parts by weight of fatty acid, 1 to 5 parts by weight of rhamnolipid, and 0.5 to 1 part by weight of vitamins to 10 to 20 parts by weight of water and performing a second stirring dissolution to obtain a second solution;

[0017] The first solution and the second solution are mixed to obtain the composite carbon source.

[0018] In a second aspect, the present application provides an application of the composite carbon source described in any one of the first aspects in sewage treatment and / or in improving the phosphorus removal performance of polyphosphate bacteria.

[0019] Furthermore, the usage of the composite carbon source in improving the phosphorus removal performance of polyphosphate bacteria is 1 to 2 g per liter of culture medium.

[0020] The above technical solution provided by the embodiment of the present application has at least the following advantages compared with the prior art:

[0021] The present invention provides a novel, highly efficient composite carbon source primarily composed of monosaccharides, fucoidan, polyols, fatty acids, rhamnolipids, and vitamins. This composite carbon source can be used to supplement carbon source nutrients in activated sludge from sewage treatment plants. This effectively supplements the carbon source required for denitrification in biochemical systems and phosphorus release by phosphate-accumulating bacteria, significantly increasing the removal rates of total nitrogen and total phosphorus, ensuring that effluent meets discharge standards. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0023] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0024] Figure 1 A schematic flow chart of a method for preparing a composite carbon source provided in an embodiment of the present application. DETAILED DESCRIPTION

[0025] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0026] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0027] In a first aspect, the present application provides a composite carbon source, which comprises the following components in parts by weight:

[0028] 10-20 parts of monosaccharide, 5-10 parts of fucoidan, 20-30 parts of polyol, 5-10 parts of fatty acid, 1-5 parts of rhamnolipid and 0.5-1 part of vitamin.

[0029] The present invention provides a novel, highly efficient composite carbon source primarily composed of monosaccharides, fucoidan, polyols, fatty acids, rhamnolipids, and vitamins. This composite carbon source can be used to supplement carbon source nutrients in activated sludge from sewage treatment plants. This effectively supplements the carbon source required for denitrification in biochemical systems and phosphorus release by phosphate-accumulating bacteria, significantly increasing the removal rates of total nitrogen and total phosphorus, ensuring that effluent meets discharge standards.

[0030] It should be noted that the components involved in the composite carbon source provided in this application, such as monosaccharides, fucoidan, polyols, fatty acids, rhamnolipids and vitamins, can all be commercially available products.

[0031] Compared to existing composite external carbon sources, this application adds fucoidan (CAS: 9072-19-9) for the first time to replace polysaccharides such as starch, effectively supplementing the carbon source required for denitrification in the biochemical system and the carbon source required for phosphorus release by phosphate-accumulating bacteria. Furthermore, it was found that the addition of fucoidan improved the phosphorus removal efficiency of phosphate-accumulating bacteria at low temperatures to a certain extent. In some specific embodiments, the fucoidan can be 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, etc., by weight.

[0032] In some specific embodiments, the monosaccharide may be 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts, etc., by weight.

[0033] In some specific embodiments, the polyol may be 20 parts, 21 parts, 22 parts, 23 parts, 24 parts, 25 parts, 26 parts, 27 parts, 28 parts, 29 parts, 30 parts, etc., by weight.

[0034] In some specific embodiments, the fatty acid may be 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, etc., by weight.

[0035] In some specific embodiments, the rhamnolipid may be 1 part, 2 parts, 3 parts, 4 parts, 5 parts, etc.

[0036] In some specific embodiments, the vitamin may be 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1.0 parts, etc.

[0037] Preferably, the composite carbon source comprises the following components in parts by weight:

[0038] 18 parts of monosaccharide, 7 parts of fucoidan, 26 parts of polyol, 7 parts of fatty acid, 4 parts of rhamnolipid and 0.5 parts of vitamin.

[0039] As an implementation method of the examples of the present application, the weight ratio of the monosaccharide, the fucoidan, the polyol and the fatty acid is (15-18):(6-8):(25-30):(6-8).

[0040] Through research, the applicant has discovered that when the weight ratio of the monosaccharide, fucoidan, polyol, and fatty acid is controlled to be (15-18):(6-8):(25-30):(6-8), adding this novel high-efficiency composite carbon source to the biochemical system can further significantly improve the removal rate of total nitrogen and total phosphorus. Preferably, the weight ratio of the monosaccharide, fucoidan, polyol, and fatty acid is 18:7:26:7.

[0041] As an implementation method of the examples of the present application, the monosaccharide is composed of glucose and fructose in a weight ratio of (20-25):1.

[0042] The present application selects a monosaccharide composed of glucose and fructose in a weight ratio of (20-25):1 for better synergy with other components. In some specific embodiments, the weight ratio of glucose and fructose can be 20:1, 21:1, 22:1, 23:1, 24:1, 25:1, etc.; preferably 22:1.

[0043] As an implementation method of the embodiment of the present application, the polyol is composed of sorbitol and glycerol in a weight ratio of (10-15):1.

[0044] The present application selects a polyol composed of sorbitol and glycerol in a weight ratio of (10-15):1 for better synergy with other components. In some specific embodiments, the weight ratio of sorbitol to glycerol can be 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, etc.; preferably 13:1.

[0045] As an implementation method of the examples of the present application, the fatty acid is composed of caprylic acid and lauric acid in a weight ratio of (5-7): (2-4).

[0046] The present application selects a fatty acid composed of n-octanoic acid and lauric acid in a weight ratio of (5-7): (2-4) to achieve a better synergistic effect of other components. In some specific embodiments, the weight ratio of n-octanoic acid to lauric acid is preferably 5:3.

[0047] As an implementation method of the examples of the present application, the vitamin is vitamin B.

[0048] In some specific embodiments, the vitamins may be selected from vitamin B1, vitamin B12, etc.

[0049] As an implementation method of the present application, Figure 1 As shown, the preparation method of the composite carbon source comprises the following steps:

[0050] 15 to 20 parts by weight of monosaccharide, 5 to 10 parts by weight of fucoidan, and 20 to 30 parts by weight of polyol are added to 40 to 60 parts by weight of water and stirred and dissolved to obtain a first solution;

[0051] Adding 5 to 10 parts by weight of fatty acid, 1 to 5 parts by weight of rhamnolipid, and 0.5 to 1 part by weight of vitamins to 10 to 20 parts by weight of water and performing a second stirring dissolution to obtain a second solution;

[0052] The first solution and the second solution are mixed to obtain the composite carbon source.

[0053] The preparation method of the composite carbon source provided in this application is simple, does not require additional specific equipment, and is suitable for industrial mass production.

[0054] In a second aspect, based on a general inventive concept, the present application provides an application of the composite carbon source described in any one of the first aspects in sewage treatment and / or improving the phosphorus removal performance of polyphosphate bacteria.

[0055] The composite carbon source provided in this application can be used to supplement carbon source nutrients in activated sludge from sewage treatment plants. It not only effectively replenishes the carbon source needed for denitrification in the biochemical system, but also supplements the carbon source needed for phosphorus release by phosphate-accumulating bacteria. This significantly improves the removal rates of total nitrogen and total phosphorus, ensuring that effluent meets discharge standards. It has broad practical application value.

[0056] As an implementation method of the examples of the present application, the usage amount of the composite carbon source in improving the phosphorus removal performance of polyphosphate bacteria is 1 to 2 g per liter of culture medium.

[0057] The present application found that the usage of the composite carbon source in improving the phosphorus removal performance of polyphosphate bacteria is 1 to 2 g per liter of culture medium, and the phosphorus removal effect of polyphosphate bacteria at low temperatures is more significant.

[0058] The present application will be further described below in conjunction with specific examples. It should be understood that these examples are intended to illustrate the present application only and are not intended to limit the scope of the present application. The experimental methods in the following examples where specific conditions are not specified are usually measured in accordance with national standards. If there are no corresponding national standards, then the methods are carried out in accordance with general international standards, conventional conditions, or according to the conditions recommended by the manufacturer.

[0059] Example 1

[0060] This example provides a composite carbon source, which includes the following components in parts by weight (each part by weight is 1g):

[0061] 10 parts of monosaccharide, 5 parts of fucoidan, 20 parts of polyol, 5 parts of fatty acid, 1 part of rhamnolipid and 0.5 parts of vitamin; wherein the monosaccharide is composed of glucose and fructose in a weight ratio of 10:1; the polyol is composed of sorbitol and glycerol in a weight ratio of 5:1; the fatty acid is composed of caprylic acid and lauric acid in a weight ratio of 1:1; and the vitamin is vitamin B12.

[0062] The preparation method of the above-mentioned composite carbon source includes the following steps: adding monosaccharides, fucoidan and polyols to 50 parts by weight of water and performing a first stirring dissolution to obtain a first solution; adding fatty acids, rhamnolipids and vitamins to 15 parts by weight of water and performing a second stirring dissolution to obtain a second solution; mixing the first solution and the second solution to obtain the composite carbon source.

[0063] Example 2

[0064] This example provides a composite carbon source, which differs from Example 1 only in that, in parts by weight (each part by weight is 1 g), the composite carbon source includes the following components: 20 parts of monosaccharide, 10 parts of fucoidan, 30 parts of polyol, 10 parts of fatty acid, 5 parts of rhamnolipid and 1 part of vitamin; the remaining steps and parameters are the same.

[0065] Example 3

[0066] This example provides a composite carbon source, which differs from Example 1 only in that, in parts by weight (each part by weight is 1 g), the composite carbon source includes the following components: 18 parts of monosaccharide, 7 parts of fucoidan, 26 parts of polyol, 7 parts of fatty acid, 4 parts of rhamnolipid and 0.5 parts of vitamin; the remaining steps and parameters are the same.

[0067] Example 4

[0068] This example provides a composite carbon source, which differs from Example 1 only in that the monosaccharide is composed of glucose and fructose in a weight ratio of 22:1; the remaining steps and parameters are the same.

[0069] Example 5

[0070] This example provides a composite carbon source, which differs from Example 1 only in that the polyol is composed of sorbitol and glycerol in a weight ratio of 13:1; the remaining steps and parameters are the same.

[0071] Example 6

[0072] This example provides a composite carbon source, which differs from Example 1 only in that the fatty acid is composed of n-octanoic acid and lauric acid in a weight ratio of 5:3; the remaining steps and parameters are the same.

[0073] Example 7

[0074] This example provides a composite carbon source, which includes the following components in parts by weight (each part by weight is 1g):

[0075] 18 parts of monosaccharide, 7 parts of fucoidan, 26 parts of polyol, 7 parts of fatty acid, 4 parts of rhamnolipid and 0.5 parts of vitamin; wherein the monosaccharide is composed of glucose and fructose in a weight ratio of 22:1; the polyol is composed of sorbitol and glycerol in a weight ratio of 13:1; the fatty acid is composed of caprylic acid and lauric acid in a weight ratio of 5:3; and the vitamin is vitamin B12.

[0076] The preparation method of the above-mentioned composite carbon source includes the following steps: adding monosaccharides, fucoidan and polyols to 50 parts by weight of water and performing a first stirring dissolution to obtain a first solution; adding fatty acids, rhamnolipids and vitamins to 15 parts by weight of water and performing a second stirring dissolution to obtain a second solution; mixing the first solution and the second solution to obtain the composite carbon source.

[0077] Comparative Example 1

[0078] This example provides a composite carbon source, which differs from Example 7 only in that the amount of fucoidan is adjusted to 0 parts and the amount of monosaccharide is adjusted to 25 parts; the remaining steps and parameters are the same.

[0079] Comparative Example 2

[0080] This example provides a composite carbon source and its application. The only difference from Example 7 is that the amount of fucoidan is adjusted to 25 parts and the amount of monosaccharide is adjusted to 0 parts; the remaining steps and parameters are the same.

[0081] Comparative Example 3

[0082] This example provides a composite carbon source and its application. The only difference from Example 7 is that the amount of polyol is adjusted to 0 parts and the amount of fatty acid is adjusted to 33 parts; the remaining steps and parameters are the same.

[0083] Comparative Example 4

[0084] This example provides a composite carbon source and its application. The only difference from Example 7 is that the amount of polyol is adjusted to 33 parts and the amount of fatty acid is adjusted to 0 parts; the remaining steps and parameters are the same.

[0085] Comparative Example 5

[0086] This example provides a composite carbon source and its application. The only difference from Example 7 is that the amount of rhamnolipid is adjusted to 0 parts; the remaining steps and parameters are the same.

[0087] Test Example 1

[0088] In this example, the composite carbon sources obtained in Examples 1 to 7 and Comparative Examples 1 to 5 were used for sewage treatment.

[0089] Test Method: Denitrification tests were conducted on sludge samples from the anoxic section of a sewage treatment plant. The sludge concentration was 4000-5000 mg / L, and the total nitrogen concentration of the raw water was 55 mg / L and the COD concentration was 107 mg / L. The composite carbon sources prepared in Examples 1-7 and Comparative Examples 1-5 and a 30% glucose aqueous solution were adjusted to a COD equivalent of 300,000 mg / L.

[0090] Thirteen groups of equal 1 L water samples to be tested were slowly stirred under the same conditions, and the adjusted composite carbon source provided in Examples 1-7 and Comparative Examples 1-5 and a 30% glucose aqueous solution were added to the water samples to be tested, respectively. The mixture was stirred at a rate of 200 r / min for 3 h, and samples were taken for testing after standing. The COD equivalent was determined according to standard HJ / T 399-2007, and the total nitrogen determination method was determined according to standard HJ 636-2012.

[0091] The test results are shown in Table 1.

[0092] Table 1

[0093] serial number 3h total nitrogen removal rate (%) Example 1 68.4 Example 2 66.9 Example 3 77.5 Example 4 72.9 Example 5 71.1 Example 6 75.2 Example 7 91.2 Comparative Example 1 62.5 Comparative Example 2 66.8 Comparative Example 3 70.0 Comparative Example 4 69.7 Comparative Example 5 73.8 Glucose aqueous solution 55.1

[0094] Test Example 2

[0095] The phosphate-accumulating bacteria seed solution was inoculated into phosphorus-rich medium A and phosphorus-rich medium B at a volume ratio of 1:10, respectively. The culture was shaken at a low temperature of 8°C for 48 hours, with the first anaerobic culture for 24 hours and the second aerobic culture for 24 hours. After 48 hours, the phosphorus removal rates of phosphorus-rich medium A and phosphorus-rich medium B were measured. Phosphorus-rich medium A: per liter of culture medium, contains 1g sodium acetate (carbon source), 82mg MgSO4, 3.7mg FeSO4, 60mg CaCl2, 0.2g (NH4)2SO4, 0.22g beef extract, 74mg K2HPO4, and 2mL trace elements; the balance is water; pH 7.0-7.2. Phosphorus-rich medium B: Each liter of medium contains 1 g of the composite carbon source (carbon source) provided in Example 7, 82 mg of MgSO4, 3.7 mg of FeSO4, 60 mg of CaCl2, 0.2 g of (NH4)2SO4, 0.22 g of beef extract, 74 mg of K2HPO4, and 2 mL of trace elements; the balance is water; pH 7.0-7.2.

[0096] After testing, it was found that compared with the phosphorus-rich medium A using sodium acetate as the carbon source, the phosphorus removal rate in the phosphorus-rich medium B using the composite carbon source provided in Example 7 was increased by 12%.

[0097] In summary, the present invention provides a novel and highly efficient composite carbon source, primarily composed of monosaccharides, fucoidan, polyols, fatty acids, rhamnolipids, and vitamins, that can be used to supplement carbon source nutrients in activated sludge from sewage treatment plants. This effectively supplements the carbon source required for denitrification in biochemical systems and the release of phosphorus by phosphate-accumulating bacteria, thereby significantly increasing the removal rates of total nitrogen and total phosphorus, ensuring that the effluent meets discharge standards.

[0098] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be understood as a hard limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numbers within the range. For example, the description of a range from 1 to 6 should be considered to have specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which applies regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0099] In this application, unless otherwise specified, the directional words used, such as "upper" and "lower", refer specifically to the directions of the drawings in the accompanying drawings. In addition, in the description of the present application specification, the terms "including", "comprising", etc. mean "including but not limited to". In this article, relational terms such as "first" and "second" are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. In this article, "and / or" describes the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. Wherein A and B can be singular or plural. In this article, "at least one" refers to one or more, and "plurality" refers to two or more. "At least one", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c", or "at least one of a, b and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, c can be single or multiple.

[0100] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A composite carbon source, characterized in that The composite carbon source comprises the following components in parts by weight: 10-20 parts of monosaccharide, 5-10 parts of fucoidan, 20-30 parts of polyol, 5-10 parts of fatty acid, 1-5 parts of rhamnolipid and 0.5-1 part of vitamin; The monosaccharide is composed of glucose and fructose in a weight ratio of (20-25):1; The polyol is composed of sorbitol and glycerol in a weight ratio of (10-15):1; The fatty acid is composed of caprylic acid and lauric acid in a weight ratio of (5-7): (2-4); The vitamin is vitamin B.

2. The composite carbon source according to claim 1, characterized in that The composite carbon source comprises the following components in parts by weight: 18 parts of monosaccharide, 7 parts of fucoidan, 26 parts of polyol, 7 parts of fatty acid, 4 parts of rhamnolipid and 0.5 parts of vitamin.

3. The composite carbon source according to claim 1, characterized in that The weight ratio of the monosaccharide, the fucoidan, the polyol and the fatty acid is (15-18):(6-8):(25-30):(6-8).

4. The composite carbon source according to claim 1, characterized in that The preparation method of the composite carbon source comprises the following steps: 15 to 20 parts by weight of monosaccharide, 5 to 10 parts by weight of fucoidan, and 20 to 30 parts by weight of polyol are added to 40 to 60 parts by weight of water and stirred and dissolved to obtain a first solution; Adding 5 to 10 parts by weight of fatty acid, 1 to 5 parts by weight of rhamnolipid, and 0.5 to 1 part by weight of vitamins to 10 to 20 parts by weight of water and performing a second stirring dissolution to obtain a second solution; The first solution and the second solution are mixed to obtain the composite carbon source.

5. Use of the composite carbon source according to any one of claims 1 to 4 in sewage treatment and / or in improving the phosphorus removal performance of polyphosphate bacteria.

6. The use according to claim 5, characterized in that The usage of the composite carbon source in improving the phosphorus removal performance of polyphosphate bacteria is 1 to 2 g per liter of culture medium.

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