High-efficiency carbon source, preparation method and application thereof

Abstract

The application relates to the technical field of water treatment, and particularly discloses a high-efficiency carbon source, a preparation method and application thereof. The high-efficiency carbon source comprises the following raw materials: corn straw, corn cob, vitamin B 12 , glycerol, sodium acetate, calcium sulfate, ethylenediaminetetraacetic acid, polymethyl acrylate, glucose and water. After the high-efficiency carbon source obtained by the application is applied to water treatment, the total nitrogen of the effluent is only 5.20 mg / L, and the ammonia nitrogen, total phosphorus, COD and BOD of the effluent are 0.13 mg / L, 0.02 mg / L, 33.30 mg / L and 6.94 mg / L respectively, which all meet the first-level A discharge standard of wastewater treatment, and the high-efficiency carbon source has good denitrification and purification effects. In addition, compared with the sodium acetate carbon source, the high-efficiency carbon source obtained by the application can greatly save the carbon source cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of water treatment, more particularly, it relates to a high-efficiency carbon source and a preparation method and application thereof. BACKGROUND

[0002] With the sustained and rapid development of China's economy, the amount of urban wastewater discharge is increasing, and industrial wastewater is one of the main influents that need to be treated in wastewater treatment plants. The biochemical property of industrial wastewater is poor, the total nitrogen of influent is high and fluctuates greatly, the biochemical oxygen demand of influent is low, the carbon-nitrogen ratio is seriously imbalanced, the phenomenon of carbon source deficiency exists for a long time, and the carbon source that can contribute to denitrification is limited. Therefore, in order to ensure that the total nitrogen of effluent meets the discharge standard, carbon source needs to be added in and outside the biological tank to meet the demand for denitrification carbon source. The main role of carbon source in wastewater treatment is to provide main nutrients for microbial synthesis and reproduction, and it is also an electron donor for denitrification.

[0003] In related technologies, the commonly used external carbon source in wastewater treatment plants is sodium acetate, which does not contain nutrients itself and will not produce intermediate products that are difficult to degrade after decomposition, and is relatively easy to be utilized by microorganisms. However, for a wastewater treatment plant with a large amount of wastewater, the dosage of carbon source is large, the time for treating wastewater is long, and the efficiency of treating wastewater is low. SUMMARY

[0004] In order to improve the effect of wastewater treatment by using carbon source, the present application provides a high-efficiency carbon source and a preparation method and application thereof.

[0005] In the first aspect, the present application provides a high-efficiency carbon source, which adopts the following technical scheme:

[0006] A high-efficiency carbon source, which comprises the following raw materials by weight: corn stalk 35-45 parts, corn cob 8-10 parts, vitamin B 12 0.6-0.8 parts, glycerol 30-40 parts, sodium acetate 5-7 parts, calcium sulfate 3-7 parts, ethylenediaminetetraacetic acid 1-3 parts, polymethyl acrylate 1-3 parts, glucose 10-15 parts, and water 45-55 parts.

[0007] The raw materials of the high-efficiency carbon source of the present application are corn stalk 35-45 parts, corn cob 8-10 parts, vitamin B 12 0.6-0.8 parts, glycerol 30-40 parts, sodium acetate 5-7 parts, calcium sulfate 3-7 parts, ethylenediaminetetraacetic acid 1-3 parts, polymethyl acrylate 1-3 parts, glucose 10-15 parts, and water 45-55 parts. The effluent quality after the water is treated by the high-efficiency carbon source meets the first-level A discharge standard of wastewater treatment, has high denitrification efficiency and purification effect, and when the corn stalk is 40 parts, the corn cob is 9 parts, the vitamin B 120.7 parts, glycerol 35 parts, sodium acetate 6 parts, calcium sulfate 5 parts, ethylenediaminetetraacetic acid 2 parts, polymethyl acrylate 2 parts, glucose 13 parts and water 50 parts, the water quality of the effluent is optimal.

[0008] By adopting the technical scheme, corn stalks are added as external carbon sources, which are widely available and low in price, have high hemicellulose content, mild hydrolysis conditions and large carbon release amount, and can degrade a large amount of microorganisms in wastewater. Corn cobs are widely available, low in price, non-toxic and harmless, and have a large specific surface area and a large number of pore structures when added as carbon sources, can perform physical adsorption, provide more attachment space for microorganisms, and have a faster denitrification rate; in addition, corn cobs contain a large number of active functional groups such as carboxyl, amino and benzene rings, which can ion exchange and adsorb or chemically adsorb heavy metal ions.

[0009] Vitamin B 12 It can promote microbial growth, enhance enzyme activity, and thus improve the denitrification reaction rate. The addition of glycerol can improve the denitrification rate of wastewater treatment.

[0010] Sodium acetate is harmless to the human body, easy to be absorbed and utilized by microorganisms, can immediately respond to the denitrification process, and has good denitrification effect. Calcium sulfate is stable in nature, odorless and tasteless, and slightly soluble in water. It can participate in the composition of cell structure material, energy transfer, regulation of enzyme activity, and maintenance of cell osmotic pressure balance, and provide a place for the growth and development of microorganisms attached to its surface by using the porous structure on the surface, which is beneficial to improve the release speed of organic carbon.

[0011] Ethylenediaminetetraacetic acid participates in enzyme synthesis or is an enzyme activator, and is used as a physiological active substance or a physiological activity regulator. After mixing with other raw materials, polymethyl acrylate can delay the volatilization time of other raw materials, so that the composite carbon source can be retained for a longer time, thereby improving the service life of the composite carbon source. In addition, polymethyl acrylate can wrap small molecules of glucose therein and release carbon through hydrogen bonding, thereby reducing the cost while achieving the purpose of continuous supply of organic carbon. Glucose is the energy source and metabolic intermediate of living cells, can be absorbed and decomposed by microorganisms, can better cultivate bacteria, improve the biodegradability of wastewater, and effectively improve the affinity of sludge.

[0012] As preferred: the corn cob is modified by the following steps, and the specific modification method comprises the following steps: mixing sulfuric acid solution with a molar concentration of 2-3 mol / L and silicic acid solution with a molar concentration of 2-2.5 mol / L, stirring uniformly to obtain a sulfuric acid-silicic acid mixed solution under the condition of 40-50℃; the volume ratio of the sulfuric acid solution to the sulfuric acid solution is 1:(6-8); the corn cob is crushed to a particle size of 30-50 mesh, boiled in boiling water for 2h, stirred in the sulfuric acid-silicic acid mixed solution for 2-3h, washed to neutral, soaked in a zinc chloride solution with a mass fraction of 30-40% at 500-700℃ for 1-2h, washed and dried to obtain the modified corn cob.

[0013] By adopting the above technical scheme, the corn cob is soaked in the sulfuric acid-silicic acid mixed solution, and the sulfuric acid and the silicic acid decompose the cellulose substances rich in the corn cob to form a large number of pore structures on the surface of the corn cob, so that the pore diameter of the surface of the corn cob is reduced, the specific surface area is increased, and the adsorption of pollutants in water is more favorable. In addition, the sulfuric acid soaking increases the functional groups on the surface of the corn cob, and improves the adsorption capacity of the corn cob. Subsequently, the zinc chloride solution is used for soaking and activation, so that the pore structure of the corn cob is more developed, the pore diameter is reduced, the specific surface area is larger, and the adsorption of the corn cob to wastewater is further improved.

[0014] As preferred: the corn cob is pretreated as follows, and the specific steps of the pretreatment are:

[0015] The corn cob is crushed, soaked in a mixed solution of calcium carbonate and hydrogen peroxide at 110-120℃, then soaked in water, dried, sterilized, soaked in a sodium citrate buffer solution, and added with a composite enzyme liquid for enzymolysis at 55-65℃ for 2-3d, high-temperature sterilized, added with a composite anaerobic bacteria agent for fermentation to obtain the pretreated corn cob;

[0016] The volume ratio of the calcium carbonate to the hydrogen peroxide is 1:(3-4); the mass ratio of the corn cob to the sodium citrate is 1:(9-11); the composite enzyme liquid is 0.5-1% of the mass of the corn cob; and the composite anaerobic bacteria agent is 0.01-0.03% of the mass of the corn cob.

[0017] By adopting the above technical scheme, the crushed corn straw is soaked in a mixed solution of calcium carbonate and hydrogen peroxide to perform alkalization treatment on the corn straw, so that the hydrogen bond inside the corn straw fiber is weakened, the cellulose is expanded, and the hemicellulose and part of the lignin inside the corn straw are dissolved. Then the corn straw is soaked in a sodium citrate buffer solution to degrade the lignin and open the crystalline structure of the cellulose to increase the contact surface of the enzyme and the substrate, thereby greatly reducing the lignin content in the corn straw, improving the reducing sugar conversion rate of the subsequent corn straw in the composite enzyme liquid, improving the enzymatic hydrolysis efficiency, and finally adding a composite anaerobic bacteria agent for fermentation, which helps to improve the fermentation efficiency and increase the total nitrogen removal rate in the wastewater. The corn straw fermentation can produce alkaline xylanase, reduce the organic chlorine in the wastewater, and improve the purification effect of the wastewater.

[0018] As preferred: the composite enzyme liquid includes the following raw materials with weight percentage: cellulase 1-5%, xylanase 0.3-0.5%, pineapple enzyme 1-3%, protease 0.1-0.3%, amylase 0.2-0.5%, Tween 80 1-1.5%, and water 90-95%.

[0019] By adopting the above technical scheme, the lignocellulose enzyme can adhere to the cellulose fiber, proliferate from the surface to the inside of the fiber, and the hemicellulose is dissolved, so that the fiber surface presents a sawtooth erosion mark, and the fiber damaged by the bacteria is easily decomposed. The use of xylanase and lignocellulose enzyme in combination can improve the hydrolysis effect of the corn straw,

[0020] The pineapple enzyme can hydrolyze the fiber protein and decompose the muscle fiber. The protease can convert the biochemical degradation macromolecules into small molecules that are easy to biodegrade. The amylase can convert the starch in the wastewater into polysaccharides and monosaccharides, and at the same time, through fermentation, the starch and other organic matters are converted into alcohol, which is then evaporated and removed. Tween 80 is added as a surfactant to improve the dispersion uniformity of the composite enzyme liquid.

[0021] As preferred: the weight ratio of the lignocellulose enzyme to the xylanase is 1:(2-4).

[0022] Under the condition that the types, contents and preparation methods of other raw materials remain unchanged, when the corn straw is pretreated by the composite enzyme liquid, the COD concentration is above 250,000 mg / L when the weight ratio of the lignocellulose enzyme to the xylanase in the composite enzyme liquid is 1:2, 1:3 and 1:4. The effluent after the treatment of the high-efficiency carbon source meets the first-level A discharge standard of wastewater treatment, and has a high denitrification effect. When the weight ratio of the lignocellulose enzyme to the xylanase in the composite enzyme liquid is 1:3, the effect is the best.

[0023] As preferred: the complex anaerobic bacteria agent comprises the following raw materials by weight percentage: yeast agent 20-30%, actinomycete agent 20-30%, photosynthetic bacteria 10-15%, and butyric acid clostridium agent 40-60%.

[0024] By adopting the above technical solution, the yeast is a facultative anaerobe and is an important nutrient functional bacteria, which can reasonably transform and efficiently absorb the amino acids and sugars synthesized by the photosynthetic bacteria and the organic matters in the wastewater, and provide high-quality nutrients and physiological active substances for other organisms. The actinomycete has strong ability to decompose complex nitrogen-containing and non-nitrogen-containing organic matters, can produce antibacterial substances by using the amino acids and other substances synthesized by the photosynthetic bacteria to inhibit pathogenic bacteria, and can inhibit the proliferation of harmful molds and harmful bacteria by using the substances required for the proliferation of the harmful molds and harmful bacteria in advance, thus creating a good environment for other useful microorganisms. The addition of the photosynthetic bacteria can improve the wastewater purification effect of the actinomycete agent. The butyric acid clostridium agent can effectively reduce the biochemical oxygen demand in the pharmaceutical wastewater and improve the biodegradability of the wastewater effluent.

[0025] The complex anaerobic bacteria agent can convert high-molecular organic matters into small-molecular organic matters under anaerobic conditions, greatly degrade and remove the chemical oxygen demand in the water, and efficiently decompose various macromolecular organic matters.

[0026] In a second aspect, the application provides a preparation method of the efficient carbon source, which is specifically implemented by the following technical solution:

[0027] The preparation method of the efficient carbon source comprises the following operation steps:

[0028] Glucose, polymethyl acrylate and water are mixed and stirred uniformly to obtain a mixture A;

[0029] The mixture A and other raw materials are stirred uniformly, and the pH value is adjusted to 6-8 to obtain the efficient carbon source.

[0030] By adopting the above technical solution, the prepared efficient carbon source improves the activity of wastewater sludge, and overcomes the problems of large dosage of traditional carbon sources such as sodium acetate, difficulty in dissolving at low temperature to produce crystallization, low absorption rate, poor total nitrogen removal rate, high danger, and strong irritating odor. The efficient carbon source obtained by the application will not crystallize at about 0℃, which provides convenience for the transportation, storage and use of the carbon source, and is mainly applied to the organic carbon source for biological denitrification and sludge domestication culture.

[0031] In a third aspect, the application provides a wastewater treatment process using the efficient carbon source, which is specifically implemented by the following technical solution:

[0032] The application discloses a water treatment process using high-efficiency carbon sources, which comprises the following operation steps: wastewater sequentially passes through a fine grid, a spiral flow grit chamber, an adjusting tank, a primary sedimentation tank, a two-stage AO composite bio-membrane biological tank, a three-stage AO biological tank, a secondary sedimentation tank, a sand-added high-speed sedimentation tank, a mechanical reaction tank, a D-shaped fiber filter tank and a disinfection tank, and finally, treated wastewater is discharged; the high-efficiency carbon sources are added into the two-stage AO composite bio-membrane biological tank and the three-stage AO biological tank, and 15.5-16.5 kg of the high-efficiency carbon sources are added per kg of total nitrogen on average.

[0033] Further, the sludge generated in the water treatment process is treated by a sludge homogenizing tank and a concentration and dehydration integrated machine.

[0034] By adopting the technical scheme, the wastewater enters the fine grid to remove suspended matters and impurities in the water, and then enters the spiral flow grit chamber to control water flow state and flow velocity by mechanical force, accelerate the sedimentation of sand particles and remove sand particles and part of organic matters; subsequently, the wastewater enters the adjusting tank to ensure normal operation of the water treatment process and is not affected by peak flow or peak concentration of the wastewater, so that the wastewater has a relatively stable water volume and uniform water quality before being treated, and the water quality and water volume are adjusted;

[0035] Then, the wastewater enters the primary sedimentation tank to remove settleable matters and floating matters, reduce the load of subsequent treatment facilities, remove 50% of the settleable matters, oil and floating matters in the wastewater and 20% of BOD, flocculate fine solid into larger particles, strengthen the solid-liquid separation effect and have a certain adsorption removal effect on colloidal matters. In addition, the primary sedimentation tank can play a role of the adjusting tank to a certain extent, has a certain homogenization effect on the water quality and reduces the impact of water quality change on the subsequent biochemical system.

[0036] Subsequently, the wastewater enters the two-stage AO composite bio-membrane biological tank and the three-stage AO biological tank to stably and efficiently remove pollutants in the wastewater. The two-stage AO composite bio-membrane biological tank comprises two stages of nitrification and denitrification, and the aerobic tank is arranged after the anoxic tank, so that the residual organic pollutants in the denitrification are further removed, and the water quality of the treated wastewater is improved. In addition, the organic carbon in the wastewater is utilized by the denitrifying bacteria in the anoxic tank, so that the organic load of the aerobic tank is reduced, and the alkalinity produced by the denitrification reaction in the anoxic tank can compensate for half of the alkalinity demand of the nitrification reaction in the aerobic tank. The composite bio-membrane enables microorganisms such as nitrifying bacteria and denitrifying bacteria in the wastewater to grow in a mode shape on the surface of the carrier, and the bio-membrane performs biological degradation to achieve the purpose of purifying the wastewater.

[0037] The tertiary AO biological treatment tank is equipped with three-dimensional elastic packing material, a water distribution device, and an aeration system. The three-dimensional elastic packing material cultivates aerobic microorganisms under aerobic conditions; the water distribution device ensures even distribution of the biological organisms in contact with the wastewater in the oxidation tank and guarantees that most of the water will remain in the tertiary biological treatment tank, preventing short-circuiting; the aeration system works by generating gases when the biofilm grows to a certain thickness, causing the microorganisms on the packing wall to undergo anaerobic metabolism due to lack of oxygen, which has a scouring effect, causing the biofilm to detach and promoting biofilm metabolism. The detached biofilm will flow into the secondary sedimentation tank with the water, reducing the pollutant concentration in the effluent.

[0038] The wastewater enters the secondary sedimentation tank for sludge-water separation, clarifying the mixed liquor and concentrating the sludge. The sludge is then returned to the tertiary AO biological tank. The remaining wastewater enters the mechanical reaction tank and then the D-type fiber filter, which uses fiber filter media to remove large molecular organic matter, viruses, bacteria, colloids, and iron impurities. Finally, the wastewater enters the disinfection tank for sterilization, yielding the treated wastewater.

[0039] As a preferred option, an iron-containing coagulant is added to the primary sedimentation tank at a dosage of 50-100g per liter of wastewater.

[0040] By adopting the above technical solution, adding iron-containing coagulant to the primary sedimentation tank can enhance the phosphorus removal effect of water treatment.

[0041] In summary, this application includes at least one of the following beneficial technical effects:

[0042] (1) The COD concentration of the efficient carbon source obtained in this application is all above 250,000 mg / L, which has a high COD concentration.

[0043] (2) When the high-efficiency carbon source obtained in this application is used to treat water, the total nitrogen in the effluent is as low as 5.20 mg / L. In addition, the ammonia nitrogen, total phosphorus, COD and BOD in the effluent are 0.13 mg / L, 0.02 mg / L, 33.30 mg / L and 6.94 mg / L, respectively, all of which meet the Class A discharge standard for wastewater treatment and have good denitrification and purification effects.

[0044] (3) By statistically analyzing the costs of using sodium acetate and high-efficiency carbon sources, it was found that the annual cost of using high-efficiency composite carbon source is about RMB 9.46 million (RMB 1,080 / ton, 24 tons per day), which is RMB 1.118 million less than that of sodium acetate. The most conservative estimate is a decrease of 10.6%, which significantly reduces the cost of carbon source.

[0045] (4) This application pre-treats corn straw and controls the weight, type and dosage of each raw material in the compound enzyme solution and the type and dosage of the compound anaerobic bacteria agent, so that the daily average values ​​of total nitrogen, ammonia nitrogen, total phosphorus, COD and BOD in the effluent are 6.22 mg / L, 0.15 mg / L, 0.02 mg / L, 32.43 mg / L and 6.42 mg / L respectively, which has a high denitrification effect.

[0046] (5) This application modifies the corn cob in the high-efficiency carbon source raw material and controls the volume ratio of sulfuric acid solution to sulfuric acid solution, so that the daily average of total nitrogen, ammonia nitrogen, total phosphorus, COD and BOD in the effluent are 5.20 mg / L, 0.13 mg / L, 0.02 mg / L, 33.30 mg / L and 6.94 mg / L respectively, which further improves the denitrification effect of the high-efficiency carbon source. Detailed Implementation

[0047] The present application will be further described in detail below with reference to specific embodiments:

[0048] The following raw materials used in this application are all commercially available products and are intended to fully disclose the raw materials used in this application. They should not be construed as limiting the source of the raw materials. Specifically: corn cob, particle size 6-8 mesh; sodium acetate, active ingredient content 58-60%; calcium sulfate, active ingredient content 95%; polymethyl methacrylate, grade HI830A; glucose, active ingredient content 90%; cellulase, enzyme activity 10000 U / g; xylanase, enzyme activity 10000 U / g; bromelain, 500000 U / g; amylase, 50000 U / g; yeast agent, effective viable count 20 billion CFU / g; actinomycetes, effective viable count 2 billion CFU / g; photosynthetic bacteria, effective viable count 20 billion CFU / mL; Clostridium butyricum, 10 billion CFU / g.

[0049] The following is an example of corn cob preparation.

[0050] Preparation Example 1

[0051] The preparation method of corn cob in Example 1 includes the following steps: at 45°C, 100 mL of sulfuric acid solution with a molar concentration of 3 mol / L and 600 mL of silicic acid solution with a molar concentration of 2.5 mol / L are mixed and stirred evenly to obtain a sulfuric acid-silicic acid mixed solution.

[0052] Corn cobs were crushed to a particle size of 50 mesh, boiled in water for 2 hours, soaked in a sulfuric acid-silicic acid mixed solution and stirred for 3 hours, washed until neutral, and then soaked in a 40% zinc chloride solution at 600℃ for 2 hours. After washing and drying, modified corn cobs were obtained.

[0053] Preparation Example 2

[0054] Preparation of corn cob in Example 2: The preparation method includes the following steps: At 45°C, 100 mL of sulfuric acid solution with a molar concentration of 3 mol / L and 700 mL of silicic acid solution with a molar concentration of 2.5 mol / L are mixed and stirred evenly to obtain a sulfuric acid-silicic acid mixed solution.

[0055] Corn cobs were crushed to a particle size of 50 mesh, boiled in water for 2 hours, soaked in a sulfuric acid-silicic acid mixed solution and stirred for 3 hours, washed until neutral, and then soaked in a 40% zinc chloride solution at 600℃ for 2 hours. After washing and drying, modified corn cobs were obtained.

[0056] Preparation Example 3

[0057] Preparation of corn cob in Example 3: The preparation method includes the following steps: At 45°C, 100 mL of sulfuric acid solution with a molar concentration of 3 mol / L and 800 mL of silicic acid solution with a molar concentration of 2.5 mol / L are mixed and stirred evenly to obtain a sulfuric acid-silicic acid mixed solution.

[0058] Corn cobs were crushed to a particle size of 50 mesh, boiled in water for 2 hours, soaked in a sulfuric acid-silicic acid mixed solution and stirred for 3 hours, washed until neutral, and then soaked in a 40% zinc chloride solution at 600℃ for 2 hours. After washing and drying, modified corn cobs were obtained.

[0059] Example 1

[0060] The method for preparing the high-efficiency carbon source in Example 1 includes the following steps:

[0061] Preparation of compound enzyme solution: Mix 1g cellulase, 0.2g bromelain, 1.5mL Tween 80 and 97.3mL water, stir well to obtain compound enzyme solution;

[0062] Preparation of compound anaerobic bacterial agent: Mix 50 mg of yeast and 50 mg of actinomycetes, stir evenly to obtain compound anaerobic bacterial agent.

[0063] Corn stalk pretreatment: Corn stalks were crushed to 50 mesh and soaked in a mixed aqueous solution of 20g calcium carbonate, 60g hydrogen peroxide, and 120mL water at 110℃. The corn stalks were then soaked in water, dried, and sterilized. 100g of corn stalks were soaked in 900mL of 0.1mol / L sodium citrate buffer solution, and enzymatically hydrolyzed for 2 days with 1mL of compound enzyme solution at 60℃. The mixture was then sterilized at high temperature. 0.02g of compound anaerobic bacteria agent was added, and fermentation was carried out at 35℃ for 4 days to obtain pretreated corn stalks. 13kg glucose, 2kg polymethyl methacrylate, and 50kg water were mixed and stirred evenly to obtain mixture A.

[0064] Mixture A with 40 kg of pretreated corn stalks, 9 kg of corn cobs, and 0.7 kg of vitamin B. 12 35 kg of glycerol, 6 kg of sodium acetate, 5 kg of calcium sulfate, and 2 kg of ethylenediaminetetraacetic acid were mixed evenly, and the pH was adjusted to 7 to obtain a high-efficiency carbon source.

[0065] Example 2

[0066] The method for preparing the high-efficiency carbon source in Example 2 includes the following steps:

[0067] Preparation of composite enzyme solution: Mix 1g cellulase, 0.4g xylanase, 0.2g bromelain, 0.4g amylase, 1.5mL Tween 80 and 96.5mL water, stir well to obtain composite enzyme solution;

[0068] Preparation of compound anaerobic bacterial agent: Mix 50 mg of yeast and 50 mg of actinomycetes, stir evenly to obtain compound anaerobic bacterial agent.

[0069] Corn stalk pretreatment: Corn stalks were crushed to 50 mesh and soaked in a mixed aqueous solution of 20g calcium carbonate, 60g hydrogen peroxide, and 120mL water at 110℃. The corn stalks were then soaked in water, dried, and sterilized. 100g of corn stalks were soaked in 900mL of 0.1mol / L sodium citrate buffer solution, and enzymatically hydrolyzed for 2 days with 1mL of compound enzyme solution at 60℃. The mixture was then sterilized at high temperature. 0.02g of compound anaerobic bacteria agent was added, and fermentation was carried out at 35℃ for 4 days to obtain pretreated corn stalks. 13kg glucose, 2kg polymethyl methacrylate, and 50kg water were mixed and stirred evenly to obtain mixture A.

[0070] Mixture A with 40 kg of pretreated corn stalks, 9 kg of corn cobs, and 0.7 kg of vitamin B. 12 35 kg of glycerol, 6 kg of sodium acetate, 5 kg of calcium sulfate, and 2 kg of ethylenediaminetetraacetic acid were mixed evenly, and the pH was adjusted to 7 to obtain a high-efficiency carbon source.

[0071] Example 3

[0072] The method for preparing the high-efficiency carbon source in Example 3 includes the following steps:

[0073] Preparation of composite enzyme solution: Mix 1g cellulase, 0.4g xylanase, 0.2g bromelain, 0.4g amylase, 1.5mL Tween 80 and 96.5mL water, stir well to obtain composite enzyme solution;

[0074] Preparation of compound anaerobic bacterial agent: Mix 20 mg of yeast, 30 mg of actinomycetes, 10 mg of photosynthetic bacteria and 40 mg of Clostridium butyricum, stir evenly to obtain compound anaerobic bacterial agent.

[0075] Corn stalk pretreatment: Corn stalks were crushed to 50 mesh and soaked in a mixed aqueous solution of 20g calcium carbonate, 60g hydrogen peroxide, and 120mL water at 110℃. The corn stalks were then soaked in water, dried, and sterilized. 100g of corn stalks were soaked in 900mL of 0.1mol / L sodium citrate buffer solution, and enzymatically hydrolyzed for 2 days with 1mL of compound enzyme solution at 60℃. The mixture was then sterilized at high temperature. 0.01g of compound anaerobic bacteria agent was added, and fermentation was carried out at 35℃ for 4 days to obtain pretreated corn stalks. 13kg glucose, 2kg polymethyl methacrylate, and 50kg water were mixed and stirred evenly to obtain mixture A.

[0076] Mixture A with 40 kg of pretreated corn stalks, 9 kg of corn cobs, and 0.7 kg of vitamin B. 12 35 kg of glycerol, 6 kg of sodium acetate, 5 kg of calcium sulfate, and 2 kg of ethylenediaminetetraacetic acid were mixed evenly, and the pH was adjusted to 7 to obtain a high-efficiency carbon source.

[0077] Example 4

[0078] The preparation method of the high-efficiency carbon source in Example 4 is the same as that in Example 3, except that the amount of compound enzyme solution used in the corn straw pretreatment is 0.5 mL, while the amount of other raw materials is exactly the same.

[0079] Example 5

[0080] Example 5 uses the same high-efficiency carbon source as Example 3, except that the amount of compound enzyme solution used in the corn straw pretreatment is 0.7 mL, while the amount of other raw materials is exactly the same.

[0081] Example 6

[0082] The preparation method of the high-efficiency carbon source in Example 6 is the same as that in Example 5, except that the amount of compound anaerobic bacteria agent used in the corn straw pretreatment is 0.02g, while the amount of other raw materials is exactly the same.

[0083] Example 7

[0084] The preparation method of the high-efficiency carbon source in Example 7 is the same as that in Example 5, except that the amount of compound anaerobic bacteria agent used in the corn straw pretreatment is 0.03g, and the amount of other raw materials is exactly the same as in Example 5.

[0085] Examples 8-10

[0086] The high-efficiency carbon source in Examples 8-10 is prepared in the same way as in Example 6, except that the corn cob used in the high-efficiency carbon source raw material is the modified corn cob prepared in Examples 1-3, and the dosage of other raw materials is exactly the same as in Example 6.

[0087] Comparative Example 1

[0088] The high-efficiency carbon source of Comparative Example 1 was prepared in the same way as that of Example 1, except that corn stalks were not pretreated in the high-efficiency carbon source raw materials, and the amount of other raw materials was exactly the same as that of Example 1.

[0089] Comparative Example 2

[0090] The high-efficiency carbon source of Comparative Example 2 was prepared in the same way as that of Example 1, except that ethylenediaminetetraacetic acid was not added to the high-efficiency carbon source raw material, while the dosage of other raw materials was exactly the same as that of Example 1.

[0091] Comparative Example 3

[0092] The high-efficiency carbon source of Comparative Example 3 was prepared in the same way as that of Example 1, except that glucose was not added to the high-efficiency carbon source raw material, while the dosage of other raw materials was exactly the same as that of Example 1.

[0093] Comparative Example 4

[0094] The high-efficiency carbon source of Comparative Example 4 was prepared in the same way as that of Example 1, except that polymethyl methacrylate was not added to the high-efficiency carbon source raw material, while the dosage of other raw materials was exactly the same as that of Example 1.

[0095] Performance Testing (Part 1)

[0096] According to HJ828-2017, the COD content in each liter of high-efficiency carbon source of Examples 1-10 and Comparative Examples 1-4 was tested, and the specific test results are shown in Table 1.

[0097] Table 1 Performance test results of different high-efficiency carbon sources

[0098]

[0099] As can be seen from the detection data in Table 1, the COD concentrations of the high-efficiency carbon sources obtained in this application are all above 250,000 mg / L, indicating a high COD concentration.

[0100] The following are applications of efficient carbon sources in water treatment.

[0101] The water treatment process includes the following steps: Wastewater sequentially passes through a fine screen and cyclone grit chamber, equalization tank and primary sedimentation tank, primary and secondary AO composite biofilm biological tank, tertiary AO biological tank, secondary sedimentation tank, sand-added high-speed sedimentation tank, mechanical reaction tank, D-type fiber filter, and disinfection tank, finally discharging the treated wastewater. Specifically, sodium bicarbonate (500-700 mg / L) is added to the cyclone sedimentation tank; polyaluminum chloride (700-900 g / t) and iron-containing coagulant (50-100 g / L) are added to the primary sedimentation tank; high-efficiency carbon source is added to both the primary and secondary AO composite biofilm biological tank and the tertiary AO biological tank; powdered activated carbon (30 mg / L), polyaluminum chloride (700-900 g / t), and polyacrylamide (2-3 g / t) are added to the secondary sedimentation tank; and sand-added high-speed sedimentation tank… A mixture of activated carbon (30 mg / L), sodium hypochlorite (5-10 mg / L), polyaluminum chloride (700-900 g / t), and polyacrylamide (2-3 g / t) is added. Polyaluminum chloride (700-900 g / t) is added to the mechanical reaction tank. Sodium hypochlorite (5-10 mg / L) is added to the D-type fiber filter. Sodium hypochlorite (5-10 mg / L) is added to the disinfection tank. The flow velocity in the sewage pipeline is 0.7 m / s.

[0102] Application Example 1

[0103] The specific method for applying the high-efficiency carbon source in water treatment in Example 1 is as follows: the high-efficiency carbon source of Example 1 is added to the primary and secondary AO composite biofilm biological tank and the tertiary AO biological tank, respectively, with an addition amount of 160 tons and a carbon-nitrogen ratio set to 6.

[0104] Application Example 2-10

[0105] The specific method for applying the high-efficiency carbon source in water treatment in Application Example 2-10 is as follows: the high-efficiency carbon source of Example 2-10 is added to the primary and secondary AO composite biofilm biological tank and the tertiary AO biological tank respectively, with an addition amount of 160 tons. The remaining operations are the same as in Application Example 1.

[0106] Application Comparative Examples 1-4

[0107] The specific method for applying the high-efficiency carbon source of Comparative Examples 1-4 in water treatment is as follows: the high-efficiency carbon source of Comparative Examples 1-4 is added to the primary and secondary AO composite biofilm biological tank and the tertiary AO biological tank respectively, with an addition amount of 160 tons. The remaining operations are the same as in Application Example 1.

[0108] Application Comparative Example 5

[0109] The carbon source for Comparative Example 5 was 160 tons of sodium acetate, and the rest of the operation was the same as in Application Example 1.

[0110] Application Comparative Example 6

[0111] The carbon source used in Comparative Example 6 was 40 tons of the high-efficiency carbon source obtained in Example 1 of this application and 160 tons of sodium acetate, and the remaining operations were the same as in Application Example 1.

[0112] Application Comparative Example 7

[0113] The carbon source used in Comparative Example 7 was 80 tons of the high-efficiency carbon source obtained in Example 1 of this application and 120 tons of sodium acetate, and the remaining operations were the same as in Application Example 1.

[0114] Application Comparative Example 8

[0115] The carbon source used in Comparative Example 8 was 120 tons of the high-efficiency carbon source obtained in Example 1 of this application and 80 tons of sodium acetate, and the remaining operations were the same as in Application Example 1.

[0116] Application Comparison Example 9

[0117] The carbon source used in Comparative Example 9 was 160 tons of the high-efficiency carbon source obtained in Example 1 of this application and 40 tons of sodium acetate, and the remaining operations were the same as in Application Example 1.

[0118] Performance Testing (Part 2)

[0119] For 10 consecutive days, the total nitrogen in the influent of Application Examples 1-10 and Application Comparative Examples 1-8 was measured daily, along with the total nitrogen, ammonia nitrogen, total phosphorus, COD, and BOD in the discharged wastewater. The test results are detailed in Table 2.

[0120] Table 2. Detection data of effluent water quality using different carbon sources.

[0121]

[0122]

[0123] As shown in Table 2, the lowest total nitrogen in the effluent obtained using the high-efficiency carbon source of this application is only 5.20 mg / L. In addition, the effluent ammonia nitrogen, total phosphorus, COD and BOD are 0.13 mg / L, 0.02 mg / L, 33.30 mg / L and 6.94 mg / L, respectively, all of which meet the Class A discharge standard for wastewater treatment (COD≤50 mg / L, BOD≤10 mg / L, ammonia nitrogen≤5 mg / L, total nitrogen≤15 mg / L, total phosphorus≤1.0 mg / L), demonstrating good denitrification and purification effects.

[0124] In Application Example 1, the daily average values ​​of total nitrogen, ammonia nitrogen, total phosphorus, COD, and BOD in the effluent were 6.77 mg / L, 0.21 mg / L, 0.03 mg / L, 29.82 mg / L, and 6.28 mg / L, respectively, all meeting the Class A discharge requirements. During the commissioning process, the operation was basically stable, and no excessively high daily average values ​​were observed. Therefore, the denitrification rate of the selected high-efficiency carbon source can reach that of sodium acetate, making it suitable for long-term use as a carbon source.

[0125] In Application Examples 1-3, the daily average values ​​of total nitrogen, ammonia nitrogen, total phosphorus, COD, and BOD in the effluent of Application Example 3 were 6.69 mg / L, 0.21 mg / L, 0.03 mg / L, 29.82 mg / L, and 6.28 mg / L, respectively. While meeting the Class A discharge requirements, this was superior to Application Examples 1 and 2, improving the effluent quality. This indicates that in corn straw pretreatment, when the compound enzyme solution is a combination of cellulase, xylanase, bromelain, amylase, Tween 80, and water, and the compound anaerobic agent is a combination of yeast, actinomycetes, photosynthetic bacteria, and Clostridium butyricum, the denitrification effect of the efficient carbon source is higher.

[0126] In Application Examples 4-5, the daily average values ​​of total nitrogen, ammonia nitrogen, total phosphorus, COD, and BOD in the effluent from Application Example 5 were 6.42 mg / L, 0.19 mg / L, 0.02 mg / L, 31.6 mg / L, and 6.35 mg / L, respectively, which were superior to those in Application Example 4, thus improving the effluent quality. This indicates that when the amount of compound enzyme solution used in corn straw pretreatment is 0.7% of the corn straw mass, the denitrification effect of the efficient carbon source is relatively high.

[0127] In Application Examples 6-7, the daily average values ​​of total nitrogen, ammonia nitrogen, total phosphorus, COD, and BOD in the effluent from Application Example 6 were 6.22 mg / L, 0.15 mg / L, 0.02 mg / L, 32.43 mg / L, and 6.42 mg / L, respectively, which were superior to those in Application Example 7, thus improving the effluent quality. This indicates that in corn straw pretreatment, when the compound anaerobic bacteria agent accounts for 0.02% of the corn straw mass, the denitrification effect of the efficient carbon source is relatively high.

[0128] In Application Examples 8-10, the daily average values ​​of total nitrogen, ammonia nitrogen, total phosphorus, COD, and BOD in the effluent of Application Example 9 were 5.20 mg / L, 0.13 mg / L, 0.02 mg / L, 33.30 mg / L, and 6.94 mg / L, respectively, which were superior to those in Application Examples 8 and 10, thus improving the effluent quality. This indicates that in corn cob modification, a volume ratio of 1:7 for sulfuric acid solution resulted in a higher nitrogen removal efficiency from the efficient carbon source.

[0129] As can be seen from the application comparison examples 1-4 and application example 1, adding ethylenediaminetetraacetic acid, glucose, polymethacrylate to the high-efficiency carbon source raw materials, as well as pretreating corn straw, can improve the denitrification effect of the high-efficiency carbon source to varying degrees.

[0130] Based on the application comparisons 5-9 and application example 1, it can be seen that by gradually replacing sodium acetate with a high-efficiency carbon source, after a 40-day test, the daily average total nitrogen in the effluent was 5.96 mg / L, while the Class A discharge requirement is below 15 mg / L, and the company's internal control standard is below 12 mg / L. This meets the discharge requirements and even exceeds the Zhejiang local standard control range. Furthermore, during the replacement of sodium acetate with a high-efficiency carbon source, the effluent ammonia nitrogen, total phosphorus, COD, and BOD all met the Class A discharge standard requirements, indicating good, stable, and efficient effluent quality.

[0131] Performance Testing (Part 3)

[0132] The application method of Application Example 1 was used for two consecutive months in September and October 2019, and the application method of Comparative Example 5 was used for two consecutive months in December 2018 and January 2019. The carbon-nitrogen ratio was adjusted to 5.5. The total nitrogen in the influent of Application Example 1 and Comparative Example 5, and the total nitrogen in the effluent and the total nitrogen removal rate were measured. The specific test results are shown in Table 3. In addition, the amount and cost of carbon source used in Application Example 1 and Comparative Example 5 were statistically analyzed. The specific statistical results are shown in Table 4.

[0133] Table 3. Detection data of effluent water quality using different carbon sources.

[0134]

[0135] Table 4. Usage and cost of different carbon sources

[0136]

[0137]

[0138] As shown in Table 3, the total nitrogen in the influent of Application Example 1 was significantly higher than that of Application Comparative Example 5, but the total nitrogen in the effluent was lower than the discharge limit. Moreover, when the average daily total nitrogen concentration in the equalization tank in October was 61.8 mg / L, the average daily total nitrogen removal rate reached 2053.4 kg, which was significantly higher than that of Application Comparative Example 5, indicating a high denitrification efficiency. The total nitrogen in the effluent was consistently lower than the discharge limit, demonstrating strong denitrification capacity. In addition, the amount of carbon source used decreased significantly.

[0139] As shown in Table 4, the centralized procurement price of sodium acetate in Application Example 5 is 920 yuan / ton (the required COD equivalent must be ≥200,000 mg / L), and the price supplied to the wastewater treatment plant is approximately 1350 yuan / ton. The price of the high-efficiency carbon source used in Application Example 1 is 1080 yuan / ton (COD equivalent ≥250,000 mg / L). Although the price of the high-efficiency carbon source is higher than the centralized procurement price of sodium acetate, based on the COD equivalent, when the sodium acetate equivalent reaches 250,000 mg / L, the price is 1150 yuan / ton. The price of the high-efficiency carbon source is 6.1% lower than the centralized procurement price of sodium acetate.

[0140] Furthermore, the price of glacial acetic acid, the raw material for sodium acetate, has increased, and the COD content of supplied sodium acetate is generally between 150,000 and 180,000 mg / L. This has led to an increase in the amount of sodium acetate used, thus increasing the purchase cost. Calculations show that approximately 22 kg of sodium acetate and 16 kg of a high-efficiency carbon source are required to remove one kilogram of total nitrogen. The carbon source cost for sodium acetate as a carbon source to remove one kilogram of total nitrogen is 21.4 kg, while the cost for a high-efficiency carbon source is 17.3 kg. These figures are calculated based on annual input costs. The annual centralized procurement cost of sodium acetate is approximately RMB 10.578 million (RMB 920 / ton; calculated based on a COD equivalent of 200,000 tons from January to June, with an actual daily average of 29 tons; calculated based on a COD equivalent of 170,000 tons from July to December, with an estimated daily average of 34.12 tons; and an annual daily average of 31.5 tons). Based on a carbon-to-nitrogen ratio of 6, the annual cost of using a high-efficiency composite carbon source is approximately RMB 9.46 million (RMB 1,080 / ton, with an average daily average of 24 tons), which is RMB 1.118 million less than that of sodium acetate, representing a conservative estimate of a 10.6% reduction. This demonstrates that applying the high-efficiency carbon source obtained in Example 1 to water treatment significantly reduces the carbon source cost for water treatment.

[0141] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A high-efficiency carbon source, characterized in that, It comprises the following raw materials in parts by weight: 35-45 parts corn stalks, 8-10 parts corn cobs, and vitamin B. 12 0.6-0.8 parts, 30-40 parts glycerol, 5-7 parts sodium acetate, 3-7 parts calcium sulfate, 1-3 parts ethylenediaminetetraacetic acid, 1-3 parts polymethyl methacrylate, 10-15 parts glucose and 45-55 parts water; The corn cob is obtained by modification through the following steps, specifically including the following operational steps: At 40-50℃, a sulfuric acid solution with a molar concentration of 2-3 mol / L and a silicate solution with a molar concentration of 2-2.5 mol / L are mixed and stirred until homogeneous to obtain a sulfuric acid-silica mixed solution; the volume ratio of the sulfuric acid solution to the silicate solution is 1:(6-8). The corn cobs are crushed to a particle size of 30-50 mesh, boiled in boiling water for 2 hours, soaked in a sulfuric acid-silicic acid mixed solution and stirred for 2-3 hours, washed until neutral, and then soaked in a zinc chloride solution with a mass fraction of 30-40% at 500-700℃ for 1-2 hours. After washing and drying, the modified corn cobs are obtained. The corn stalks undergo the following pretreatment, the specific steps of which are as follows: Corn stalks are crushed to a particle size of 40-60 mesh, soaked in a mixed aqueous solution of calcium carbonate and hydrogen peroxide at 110-120℃, then soaked in water, dried, and sterilized. The corn stalks are then soaked in a 0.1 mol / L sodium citrate buffer solution, enzymatically hydrolyzed with a compound enzyme solution at 55-65℃ for 2-3 days, sterilized at high temperature, and fermented with a compound anaerobic agent at 30-40℃ for 4-6 days to obtain pretreated corn stalks. The mass ratio of calcium carbonate to hydrogen peroxide is 1:(3-4); the water content in the mixed aqueous solution of calcium carbonate and hydrogen peroxide is 150% of the total volume of calcium carbonate and hydrogen peroxide; the mass ratio of corn stalks to sodium citrate is 1:(9-11); the compound enzyme solution is 0.5-1% of the mass of corn stalks; the compound anaerobic agent is 0.01-0.03% of the mass of corn stalks. The compound enzyme solution comprises the following raw materials in weight percentage: cellulase 0.5-1%, xylanase 0.3-0.5%, bromelain 0.1-0.3%, amylase 0.2-0.5%, Tween 80 1-1.5%, and water 90-95%; The compound anaerobic bacterial agent comprises the following raw materials in weight percentage: 20-30% yeast, 20-30% actinomycetes, 10-15% photosynthetic bacteria, and 30-50% Clostridium butyricum.

2. The high-efficiency carbon source according to claim 1, characterized in that: The weight ratio of cellulase to xylanase is 1:(2-4).

3. A method for preparing a high-efficiency carbon source according to any one of claims 1-2, characterized in that, It includes the following operating steps: Glucose, polymethacrylate and water are mixed and stirred until homogeneous to obtain mixture A; Mix mixture A and other raw materials thoroughly, adjust the pH value to 6-8, and obtain a high-efficiency carbon source.

4. The application of the high-efficiency carbon source according to any one of claims 1-2 in a water treatment process, characterized in that, The water treatment process includes the following steps: wastewater sequentially passes through a fine screen and vortex grit chamber, equalization tank and primary sedimentation tank, primary and secondary AO composite biofilm biological tank, tertiary AO biological tank, secondary sedimentation tank, high-speed sedimentation tank with added sand, mechanical reaction tank, D-type fiber filter, and disinfection tank, and finally the treated wastewater is discharged; the high-efficiency carbon source is added to the primary and secondary AO composite biofilm biological tank and the tertiary AO biological tank, with an average addition rate of 15.5-16.5 kg of high-efficiency carbon source per kilogram of total nitrogen removed.

5. The application of the high-efficiency carbon source in water treatment processes according to claim 4, characterized in that: Iron-containing coagulant is added to the primary sedimentation tank at a dosage of 50-100g per liter of wastewater.

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