Efficient liquid composite carbon source as well as preparation method and application thereof

Abstract

The invention relates to the technical field of sewage treatment, and discloses an efficient liquid composite carbon source and a preparation method and application thereof.The liquid composite carbon source is prepared from, by mass, 8%-15% of glycerol, 8%-15% of propylene glycol, 8%-15% of dipropylene glycol, 8%-15% of ethylene glycol, 8%-15% of butanol, 8%-15% of isobutanol, 15%-25% of 2-glycolic acid, 15%-25% of acetic acid, 10%-20% of sodium acetate and 1%-2% of anionic surfactant. 0.2-0.6% of a composite biological enzyme and the balance of water. The COD equivalent of the liquid composite carbon source provided by the invention is 60-80 thousand mg / L, and the raw materials are low in price, non-toxic and harmless, do not contain flammable and explosive substances or other dangerous chemicals, and are easy to add, transport and store; in addition, the liquid composite carbon source has relatively high denitrification rate, is simple in microbial acclimation, does not influence the effluent quality, and can be widely applied to various biochemical treatment processes of domestic sewage, industrial wastewater and the like.

Description

Technical Field

[0001] The invention relates to the technical field of sewage treatment, and in particular to a high-efficiency liquid composite carbon source and a preparation method and application thereof. Background Art

[0002] In the biological denitrification process of sewage treatment, the selection of carbon source is crucial to improving denitrification efficiency and reducing the total nitrogen content of effluent. The choice of carbon source not only affects the growth and metabolism of microorganisms, but also directly affects the treatment cost and effluent quality. The traditional single carbon source has high cost of addition, the domesticated microorganisms have poor impact resistance, and contain flammable, explosive or biotoxic substances, resulting in low overall cost performance. Therefore, composite carbon sources came into being. Comprehensive comparison shows that composite carbon sources contain a variety of organic substances, can cultivate highly adaptable microbial communities, and can withstand large water quality fluctuations; and the raw materials of composite carbon sources are mostly recovered from industrial waste, such as food processing waste liquid, biomass fermentation residues, etc. These raw materials are low in cost and can effectively reduce the cost of adding carbon sources.

[0003] However, composite carbon sources still face many challenges in practical applications, including:

[0004] Difficult quality control: Due to the diverse sources of raw materials for composite carbon sources, their composition and quality are difficult to strictly control, resulting in unstable product quality and affecting the treatment effect.

[0005] Poor storage stability: The composite carbon source is prone to deterioration during storage, affecting its use effect. Especially in high temperature and humid environment, the storage stability problem is more prominent.

[0006] High production cost: Although the raw material cost of composite carbon sources is relatively low, the production process is complicated and requires the mixing and fermentation of multiple organic substances, resulting in production costs that are often higher than traditional single carbon sources.

[0007] The actual application effect is not ideal: In actual applications, the effect of composite carbon sources is often unsatisfactory and unstable, and the total nitrogen content of the effluent is difficult to reach the expected standard, which limits its widespread application in sewage treatment.

[0008] Therefore, there is an urgent need to develop a more efficient, safe and economical composite carbon source. Summary of the invention

[0009] The present invention aims to provide a high-efficiency liquid composite carbon source and a preparation method and application thereof, so as to solve the safety and cost problems of the composite carbon source in the prior art.

[0010] To achieve the above-mentioned purpose, the present invention adopts the following technical scheme: an efficient liquid composite carbon source, characterized in that: in mass percentage, it includes 8-15% of glycerol, 8-15% of propylene glycol, 8-15% of dipropylene glycol, 8-15% of ethylene glycol, 8-15% of butanol, 8-15% of isobutanol, 15-25% of 2-hydroxyacetic acid, 15-25% of acetic acid, 10-20% of sodium acetate, 1-2% of anionic surfactant, 0.2-0.6% of composite biological enzyme, and the balance is water.

[0011] Preferably, as an improvement, the composite biological enzyme comprises at least one of lipase, cellulase and protease.

[0012] Preferably, as an improvement, the COD equivalent is 600,000 to 800,000 mg / L and the pH value is 4 to 8.

[0013] Preferably, as an improvement, the preparation of a high-efficiency liquid composite carbon source comprises the following steps:

[0014] Step I, heating water to 25°C and stirring;

[0015] Step II, add glycerol, propylene glycol, dipropylene glycol, ethylene glycol, butanol, isobutanol, 2-hydroxyacetic acid, acetic acid, sodium acetate and anionic surfactant in sequence, and continue stirring;

[0016] Step III, add compound biological enzyme and continue stirring until completely dissolved;

[0017] Step IV, let the solution stand to allow bubbles in the solution to escape;

[0018] Step V: If the sampling and testing meet the standards, the high-efficiency liquid composite carbon source is prepared.

[0019] Preferably, as an improvement, in step I, the stirring speed is 100-150 rpm.

[0020] Preferably, as an improvement, in step II, the stirring speed is 200-300 rpm, and the stirring time is 20-30 rpm.

[0021] Preferably, as an improvement, in step III, the stirring speed is 150-200 rpm.

[0022] Preferably, as an improvement, in step IV, the standing time is 10 to 20 minutes.

[0023] Preferably, as an improvement, a high-efficiency liquid composite carbon source is used in the preparation of a sewage treatment agent.

[0024] Preferably, as an improvement, the sewage treatment agent is a denitrification promoter.

[0025] The principle and advantage of this solution are: in actual application, in this technical solution, the inventor has comprehensively optimized the composition and preparation process of the carbon source in view of the problems existing in the practical application stage of the composite carbon source in the prior art. In the composition of the composite carbon source, propylene glycol, dipropylene glycol and ethylene glycol are used as carbon sources and energy sources for microorganisms, which promote their growth and metabolism, and are easily absorbed and utilized by microorganisms, which helps to improve the denitrification and denitrification rate during sewage treatment. In addition, this technical solution also compounds butanol and isobutanol in organic alcohols, both of which have the effect of enhancing the solubility and stability of the composite carbon source on the basis of providing energy. Small molecular acids such as 2-hydroxyacetic acid and acetic acid can provide a direct carbon source for denitrifying bacteria, promote the denitrification reaction, and can also adjust the pH value of sewage to create a suitable growth environment for microorganisms. Sodium acetate can not only be used as a carbon source, but also respond quickly to the denitrification process and increase the denitrification rate. Anionic surfactants have good emulsification and water solubility, can increase the stability of composite carbon sources, make them easier to disperse and dissolve in water, and can be used as carbon sources by microorganisms. Composite biological enzymes can decompose different types of organic matter, making them easier to be absorbed and used by microorganisms. The liquid composite carbon source provided by the present invention has a COD equivalent of 600,000 to 800,000 mg / L, the raw material price is cheap, non-toxic and harmless, does not contain flammable and explosive substances or other hazardous chemicals, and is easy to add, transport and store; in addition, the liquid composite carbon source has a high denitrification rate, the microorganism is simple to domesticate, does not affect the effluent water quality, and can be widely used in a variety of biochemical treatment processes such as domestic sewage and industrial wastewater. The composite carbon source prepared above is used in the field of sewage treatment, and it can be used as a supplementary carbon source in anoxic denitrification sewage treatment processes, providing sufficient carbon sources for denitrifying bacteria, promoting denitrification reactions, and improving denitrification efficiency. In the technical research and development stage, the storage stability, quality control and maintenance of the actual application effect of the composite carbon source are several research and development difficulties of this technical solution. For the storage stability of the composite carbon source, the present technical solution increases the stability of the composite carbon source by adding anionic surfactants, making it easier to disperse and dissolve in water, and at the same time reasonably matches the raw materials to improve the storage stability. For quality control, the present technical solution optimizes the types and components of each raw material, adjusts the ratio, realizes the precise control of the composite carbon source components, and solves the problem of unstable quality. In addition, for the application effect of the composite carbon source, the present technical solution achieves the composite carbon source through the synergistic effect between components, which is easy to be degraded by microorganisms, has high bioavailability, fast denitrification reaction rate, can effectively improve the denitrification efficiency, and solves the problem of unsatisfactory application effect. During the research and development stage, the inventor tried to simply compound the carbon sources commonly used in the prior art, such as acetic acid, ethanol, etc., without considering the synergy between components and the optimization of the ratio, resulting in unsatisfactory nitrification and denitrification effects, and unable to achieve the expected total nitrogen removal rate. There may be mutual inhibition or inability to fully play a role between the components, resulting in poor overall performance.

[0026] In summary, the beneficial effects of this technical solution are:

[0027] 1. The composite carbon source raw material of the present invention is low-priced and easy to obtain, and the finished product is safe, environmentally friendly, non-toxic and harmless, and easy to add, transport and store.

[0028] 2. The composite carbon source is easily degraded by microorganisms, has high bioavailability, and can promote the rapid reproduction of denitrifying and denitrifying heterotrophic bacteria. There is no problem of residual residues adversely affecting the subsequent effluent standards.

[0029] 3. The composite carbon source of the present invention has a fast denitrification reaction speed, is applicable to common sewage treatment systems, and will not affect the type and content of microbial populations in the system, thus avoiding the problem of short-term adaptability of microorganisms before and after the addition of carbon sources.

[0030] 4. The innovatively introduced composite biological enzyme can accelerate the utilization of carbon sources by microorganisms, improve denitrification efficiency, and enhance the performance of composite carbon sources. DETAILED DESCRIPTION

[0031] The following is further described in detail through specific implementations, but the implementation of the present invention is not limited thereto. Unless otherwise specified, the technical means used in the following implementations are conventional means well known to those skilled in the art; the experimental methods used are all conventional methods; the materials, reagents, etc. used can all be obtained from commercial channels.

[0032] Program Overview:

[0033] A high-efficiency liquid composite carbon source comprises, by mass percentage, 8-15% of glycerol, 8-15% of propylene glycol, 8-15% of dipropylene glycol, 8-15% of ethylene glycol, 8-15% of butanol, 8-15% of isobutanol, 15-25% of 2-hydroxyacetic acid, 15-25% of acetic acid, 10-20% of sodium acetate, 1-2% of anionic surfactant, 0.2-0.6% of composite biological enzyme, and the balance is water.

[0034] The composite biological enzyme comprises at least one of lipase, cellulase and protease.

[0035] The anionic surfactant was fatty acid methyl ester ethoxylate sulfonate (FMES).

[0036] A method for preparing a high-efficiency liquid composite carbon source comprises the following steps:

[0037] Step I, heating water to 25°C and stirring at a stirring speed of 100-150 rpm;

[0038] Step II, add glycerol, propylene glycol, dipropylene glycol, ethylene glycol, butanol, isobutanol, 2-hydroxyacetic acid, acetic acid, sodium acetate and anionic surfactant in sequence, and stir at a stirring speed of 200-300 rpm for 20-30 min;

[0039] Step III, slowly add the composite biological enzyme and continue stirring until completely dissolved at a stirring speed of 150-200 rpm;

[0040] Step IV, stop stirring and let stand for 10 to 20 minutes to allow bubbles in the solution to escape;

[0041] Step V, sampling and testing various indicators of the composite carbon source, that is, preparing a high-efficiency liquid composite carbon source, with a COD equivalent of 600,000 to 800,000 mg / L and a pH value of 4 to 8, to ensure that it meets the quality requirements.

[0042] Example 1 Liquid composite carbon source.

[0043] The composite carbon source provided in this embodiment comprises the following components in weight percentage: 10% glycerol, 10% propylene glycol, 10% dipropylene glycol, 10% ethylene glycol, 10% butanol, 10% isobutanol, 20% 2-hydroxyacetic acid, 20% acetic acid, 15% sodium acetate, 1.5% anionic surfactant, 0.4% composite biological enzyme, and 13.6% water. The composite enzyme is cellulase, protease and lipase compounded in a mass ratio of 6:2:2.

[0044] The preparation method of the composite carbon source is as follows: first, water is heated to 25°C, stirred at a stirring speed of 120rpm, and then propylene glycol, propylene glycol, dipropylene glycol, ethylene glycol, butanol, isobutanol, 2-hydroxyacetic acid, acetic acid, sodium acetate and anionic surfactant are added in sequence, and stirred at a stirring speed of 250rpm for 25min; then the composite biological enzyme is slowly added, and stirring is continued until it is completely dissolved, and the stirring speed is 180rpm; then the stirring is stopped, and the solution is allowed to stand for 15min to allow bubbles in the solution to escape; finally, sampling is performed to detect various indicators of the composite carbon source to ensure that the quality requirements are met, and the composite carbon source can be obtained.

[0045] Example 2 Liquid composite carbon source.

[0046] The composite carbon source provided in this embodiment comprises the following components in weight percentage: 12% glycerol, 12% propylene glycol, 12% dipropylene glycol, 12% ethylene glycol, 12% butanol, 12% isobutanol, 22% 2-hydroxyacetic acid, 22% acetic acid, 18% sodium acetate, 1.8% anionic surfactant, 0.5% composite biological enzyme, and 7.2% water. The composite enzyme is cellulase, protease and lipase compounded in a mass ratio of 6:3:1.

[0047] The preparation method of the composite carbon source is as follows: first, water is heated to 25°C, stirred at a stirring speed of 100 rpm, and then propylene glycol, propylene glycol, dipropylene glycol, ethylene glycol, butanol, isobutanol, 2-hydroxyacetic acid, acetic acid, sodium acetate and anionic surfactant are added in sequence, and stirred at a stirring speed of 200 rpm for 30 minutes; then the composite biological enzyme is slowly added, and stirring is continued until it is completely dissolved, and the stirring speed is 150 rpm; then the stirring is stopped, and the solution is allowed to stand for 10 minutes to allow bubbles in the solution to escape; finally, sampling is performed to detect various indicators of the composite carbon source to ensure that the quality requirements are met, and the composite carbon source can be obtained.

[0048] Example 3 Liquid composite carbon source.

[0049] The composite carbon source provided in this embodiment comprises the following components in weight percentage: 15% glycerol, 15% propylene glycol, 15% dipropylene glycol, 15% ethylene glycol, 15% butanol, 15% isobutanol, 25% 2-hydroxyacetic acid, 25% acetic acid, 20% sodium acetate, 2% anionic surfactant, 0.6% composite biological enzyme, and 0% water. The composite enzyme is cellulase, protease and lipase compounded in a mass ratio of 7:2:1.

[0050] The preparation method of the composite carbon source is as follows: first, water is heated to 25°C, stirred at a stirring speed of 150rpm, and then propylene glycol, propylene glycol, dipropylene glycol, ethylene glycol, butanol, isobutanol, 2-hydroxyacetic acid, acetic acid, sodium acetate and anionic surfactant are added in sequence, and stirred at a stirring speed of 300rpm for 20min; then the composite biological enzyme is slowly added, and stirring is continued until it is completely dissolved, and the stirring speed is 200rpm; then the stirring is stopped, and the solution is allowed to stand for 20min to allow bubbles in the solution to escape; finally, sampling is performed to detect various indicators of the composite carbon source to ensure that the quality requirements are met, and the composite carbon source can be obtained.

[0051] Application Example 1

[0052] A certain urban sewage treatment plant has a treatment scale of 10,000 cubic meters per day and a total nitrogen concentration of 25 mg / L in raw water. The composite carbon source of Example 1 of the present invention is used as a supplementary carbon source at a dosage of 100 mg / L, and is added to the starting point of the anoxic denitrification tank. After running for a period of time, the total nitrogen concentration of the effluent is stabilized below 8 mg / L, the total nitrogen removal rate reaches 68%, and the effluent COD concentration drops to below 30 mg / L.

[0053] Application Example 2

[0054] The sewage treatment plant in an industrial park mainly treats sewage from chemical enterprises, with complex water quality and high total nitrogen concentration. After adopting the composite carbon source of the present invention, under the same treatment conditions, compared with the use of traditional carbon sources, the total nitrogen removal rate is increased by about 25%, the total nitrogen in the effluent is stabilized below 10 mg / L, and the COD concentration is reduced to below 50 mg / L.

[0055] Experimental Example 1

[0056] In order to further verify the high efficiency of the composite carbon source of the present invention, a comparative experiment was conducted. The composite carbon source of the present invention and the carbon source of the control group were respectively applied to the same sewage treatment system, and the treatment effect was tested under the same test environment, dosage, total nitrogen concentration in sewage (25 mg / L), residence time 30 min and sludge concentration 3500 mg / L.

[0057] The experimental design is as follows:

[0058] Experimental group 1: composite carbon source according to Example 1 of the present invention;

[0059] Control group 1: sodium acetate;

[0060] Control group 2: composite carbon source A, the specific raw materials and mass percentages are 85% glycerol, 5% potassium acetate, 2% methanol, and the rest is water;

[0061] Control group 3: composite carbon source B, the specific raw materials and mass percentages are 1% sodium formate, 5% sodium acetate, 5% sodium propionate, 40% glucose, and the rest is water;

[0062] Control group 4: The difference between the composite carbon source and the composite carbon source of experimental group 1 is that the composite carbon source does not contain composite enzymes;

[0063] Sewage conditions and test conditions: refer to the pollutant discharge standard for urban sewage treatment plants (GB 18918-2002).

[0064] The test results are shown in Table 1: the composite carbon source of the present invention is superior to conventional carbon sources and other composite carbon sources in terms of total nitrogen removal rate, effluent total nitrogen, effluent COD, denitrification rate, etc. Specifically, the total nitrogen removal rate of the composite carbon source of the present invention is 25.6% higher than that of sodium acetate (control group 1), 16.4% higher than that of composite carbon source A (control group 2), 12% higher than that of composite carbon source B (control group 3), and 3.2% higher than that of control group 4; the effluent total nitrogen is 6.4 mg / L lower than that of sodium acetate, 4.1 mg / L lower than that of composite carbon source A, 3 mg / L lower than that of composite carbon source B, and 0.8 mg / L lower than that of control group 4; the effluent COD is 17 mg / L lower than that of sodium acetate, 12 mg / L lower than that of composite carbon source A, 10 mg / L lower than that of composite carbon source B, and 2 mg / L lower than that of control group 4; the denitrification rate is 7.8 mgNO3-N / (gMLVSS·h) faster than that of sodium acetate, 6.0 mgNO3-N / (gMLVSS·h) faster than that of composite carbon source A, and 4.5 mgNO3-N / (gMLVSS·h) faster than that of composite carbon source B. NO3-N / (gMLVSS·h), 2.2mgNO3-N / (gMLVSS·h) faster than the control group 4; the sludge output is 0.27gMLSS / L less than sodium acetate, 0.20gMLSS / L less than the composite carbon source A, 0.15gMLSS / L less than the composite carbon source B, and 0.05gMLSS / L less than the control group 4. This shows that the composite carbon source of the present invention has significant high efficiency and advantages.

[0065] Table 1

[0066]

[0067] The above is only an embodiment of the present invention, and the common knowledge such as the known specific technical solutions and / or characteristics in the solution is not described in detail here. It should be pointed out that for those skilled in the art, without departing from the technical solution of the present invention, several modifications and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A high-efficiency liquid composite carbon source, characterized in that: In terms of mass percentage, the invention comprises 8-15% of glycerol, 8-15% of propylene glycol, 8-15% of dipropylene glycol, 8-15% of ethylene glycol, 8-15% of butanol, 8-15% of isobutanol, 15-25% of 2-hydroxyacetic acid, 15-25% of acetic acid, 10-20% of sodium acetate, 1-2% of anionic surfactant, 0.2-0.6% of composite biological enzyme, and the balance is water.

2. A high-efficiency liquid composite carbon source according to claim 1, characterized in that: The composite biological enzyme comprises at least one of lipase, cellulase and protease.

3. A high-efficiency liquid composite carbon source according to claim 2, characterized in that: The COD equivalent is 600,000 to 800,000 mg / L, and the pH value is 4 to 8.

4. The preparation of a high-efficiency liquid composite carbon source according to any one of claims 1 to 3, characterized in that: The steps include: Step I, heating water to 25°C and stirring; Step II, add glycerol, propylene glycol, dipropylene glycol, ethylene glycol, butanol, isobutanol, 2-hydroxyacetic acid, acetic acid, sodium acetate and anionic surfactant in sequence, and continue stirring; Step III, add compound biological enzyme and continue stirring until completely dissolved; Step IV, let the solution stand to allow bubbles in the solution to escape; Step V: If the sampling and testing meet the standards, the high-efficiency liquid composite carbon source is prepared.

5. The method for preparing a high-efficiency liquid composite carbon source according to claim 4, characterized in that: In step I, the stirring speed is 100-150 rpm.

6. The method for preparing a high-efficiency liquid composite carbon source according to claim 5, characterized in that: In step II, the stirring speed is 200-300 rpm, and the stirring time is 20-30 rpm.

7. The method for preparing a high-efficiency liquid composite carbon source according to claim 6, characterized in that: In step III, the stirring speed is 150-200 rpm.

8. The method for preparing a high-efficiency liquid composite carbon source according to claim 7, characterized in that: In step IV, the standing time is 10 to 20 minutes.

9. Use of a high-efficiency liquid composite carbon source according to any one of claims 1 to 3 in the preparation of a sewage treatment agent.

10. The use of a high-efficiency liquid composite carbon source in the preparation of a sewage treatment agent according to claim 9, characterized in that: The sewage treatment agent is a denitrification promoter.

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