A composite carbon source for wastewater denitrification and its preparation method

Abstract

The present invention relates to the technical field of water treatment, and provides a composite carbon source for wastewater denitrification and a preparation method thereof. A composite carbon source for wastewater denitrification is composed of the following components in mass percentages: 10% - 20% of saccharide substances, 5% - 10% of organic acids, 8% - 15% of alcohol substances, 3% - 7% of organic salts, 0.01% - 0.1% of inorganic salts, 3% - 8% of denitrifying bacteria, and the balance of water. The organic salt is lactate, and the inorganic salts include carbonates and / or bicarbonates. Through the above technical solution, the problem of poor denitrification effect of the composite carbon source in the related art is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment, and specifically, to a composite carbon source for wastewater denitrification and a preparation method thereof. Background Art

[0002] Composite carbon sources are carbon source agents used for wastewater treatment and are widely applied to the biochemical wastewater treatment of industries such as municipal sewage, slaughtering, food, metal surface, electroplating, etc.

[0003] In the case of microbial denitrification, when denitrification is carried out, denitrifying bacteria must consume additional carbon sources to provide energy, and the composite carbon source plays the role of providing a carbon source. The composite carbon source is a new type of carbon source product, which has the characteristics of less dosage, being easily absorbed and utilized by microorganisms, reducing the production of organic sludge, and improving the activity of sludge. The composite carbon source is an essential carbon source product for starting up and commissioning a sewage biochemical system or shortening the recovery time, and is also the first choice of carbon source for traditional denitrification and chlorate removal processes. However, traditional composite carbon sources generally have the problem of poor denitrification effect. Summary of the Invention

[0004] The present invention provides a composite carbon source for wastewater denitrification and a preparation method thereof, which solves the problem of poor denitrification effect of the composite carbon source in the related art.

[0005] The technical solution of the present invention is as follows:

[0006] A composite carbon source for wastewater denitrification is composed of the following components in mass percentages: 10% - 20% of saccharide substances, 5% - 10% of organic acids, 8% - 15% of alcohol substances, 3% - 7% of organic salts, 0.01% - 0.1% of inorganic salts, 3% - 8% of denitrifying bacteria, and the balance of water. The organic salt is lactate, and the inorganic salts include carbonates and / or bicarbonates.

[0007] As a further technical solution, the saccharide substances include one or more of glucose, xylose, fructose, molasses.

[0008] As a further technical solution, the saccharide substance is molasses.

[0009] The present invention uses molasses as the saccharide substance, further improving the denitrification effect of the composite carbon source.

[0010] As a further technical solution, the organic acids include one or more of formic acid, oxalic acid, citric acid, gallic acid, mandelic acid.

[0011] As a further technical solution, the organic acids include gallic acid and mandelic acid, and the mass of gallic acid ≥ the mass of mandelic acid.

[0012] The present invention uses gallic acid and mandelic acid as organic acids, and further improves the denitrification effect of the composite carbon source by specifying that the mass of gallic acid ≥ the mass of mandelic acid.

[0013] As a further technical solution, the mass ratio of the gallic acid to the mandelic acid is 5:3 to 6:2.

[0014] The present invention specifies that the mass ratio of the gallic acid to the mandelic acid is 5:3 to 6:2, which further improves the denitrification effect of the composite carbon source.

[0015] As a further technical solution, the alcohol substances include one or more of methanol, ethanol, and ethylene glycol.

[0016] As a further technical solution, the organic salt is sodium lactate, and the inorganic salts include sodium carbonate and / or sodium bicarbonate.

[0017] As a further technical solution, the COD value of the composite carbon source ≥ 300,000 mg / L, and the density at 20 °C is 1.0 to 1.26 g / cm 3 .

[0018] The present invention also provides a preparation method of the composite carbon source, which includes the following steps: after mixing the organic salt with water, successively adding the saccharide substances, organic acids, alcohol substances, inorganic salts and mixing evenly, and finally adding denitrifying bacteria and mixing evenly to obtain the composite carbon source.

[0019] The working principle and beneficial effects of the present invention are as follows:

[0020] 1. The present invention provides a composite carbon source for wastewater denitrification, which includes saccharide substances, organic acids, alcohol substances, organic salts, inorganic salts, denitrifying bacteria and water. By optimizing the raw materials and the dosage of each raw material, and using the organic salt and the inorganic salt in a compound manner, the denitrification effect of the composite carbon source is synergistically improved.

[0021] 2. Compared with traditional organic salts such as acetate salts and inorganic salts such as phosphate salts, sodium lactate is used as the organic salt and carbonate and / or bicarbonate are used as the inorganic salts in the present invention, which improves the denitrification effect of the composite carbon source. In addition, the composite carbon source provided by the present invention has the characteristics of fast reaction, fast absorption and no freezing at minus temperature, and is especially suitable for use in water plants in northern China in winter. It performs excellently in the treatment of total nitrogen in wastewater from industries such as urban sewage, river regulation, printing and dyeing, food, breeding, slaughtering, electroplating, chemical engineering, and landfill leachate, has low requirements for the total nitrogen treatment process of water plants, and is suitable for sewage treatment plants with short residence times. Specific Embodiments

[0022] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present invention.

[0023] The parameters of the raw materials in the following examples and comparative examples are as follows:

[0024] The type of denitrifying bacteria is HE-M-A1, and the active substance content is > 20 billion cuf / g. It is purchased from Aladdin Environmental Protection Technology (Suzhou) Co., Ltd.;

[0025] The molasses is cane molasses.

[0026] Example 1

[0027] S1. Prepare materials: The composite carbon source is composed of the following components by mass percentage: glucose 15%, formic acid 8%, methanol 11%, sodium lactate 5%, sodium bicarbonate 0.05%, denitrifying bacteria 5%, and the balance of water. The denitrifying bacteria are composed of bacillus and pseudomonas in a mass ratio of 1:3;

[0028] S2. After mixing sodium lactate and water evenly, add glucose and stir until dissolved, then add formic acid, methanol, and sodium bicarbonate and mix evenly. Finally, add denitrifying bacteria and mix evenly to obtain the composite carbon source.

[0029] Example 2

[0030] S1. Prepare materials: The composite carbon source is composed of the following components by mass percentage: xylose 10%, oxalic acid 5%, ethylene glycol 8%, sodium lactate 3%, sodium carbonate 0.01%, denitrifying bacteria 3%, and the balance of water. The denitrifying bacteria are composed of lactobacillus plantarum and pseudomonas in a mass ratio of 1:3;

[0031] S2. After mixing sodium lactate and water evenly, add xylose and stir until dissolved, then add oxalic acid, ethylene glycol, and sodium carbonate and mix evenly. Finally, add denitrifying bacteria and mix evenly to obtain the composite carbon source.

[0032] Example 3

[0033] S1. Prepare materials: The composite carbon source is composed of the following components by mass percentage: fructose 20%, citric acid 10%, ethanol 15%, sodium lactate 7%, sodium bicarbonate 0.1%, denitrifying bacteria 8%, and the balance of water. The denitrifying bacteria are composed of lactobacillus plantarum and bacillus in a mass ratio of 1:3;

[0034] S2. After mixing sodium lactate and water evenly, add fructose and stir until dissolved. Then add citric acid, ethanol, and sodium bicarbonate and mix evenly. Finally, add denitrifying bacteria and mix evenly to obtain the composite carbon source.

[0035] Example 4

[0036] The difference from Example 1 is only that glucose is replaced with an equal amount of molasses.

[0037] Example 5

[0038] The difference from Example 4 is only that formic acid is replaced with an equal amount of gallic acid.

[0039] Example 6

[0040] The difference from Example 4 is only that formic acid is replaced with an equal amount of mandelic acid.

[0041] Example 7

[0042] The difference from Example 5 is only that: S1. Preparation of materials: The composite carbon source is composed of the following components in mass percentage: glucose 15%, gallic acid 3%, mandelic acid 5%, methanol 11%, sodium lactate 5%, sodium bicarbonate 0.05%, denitrifying bacteria 5% and the balance of water. The denitrifying bacteria are composed of bacillus and pseudomonas in a mass ratio of 1:3.

[0043] Example 8

[0044] The difference from Example 5 is only that: S1. Preparation of materials: The composite carbon source is composed of the following components in mass percentage: glucose 15%, gallic acid 4%, mandelic acid 4%, methanol 11%, sodium lactate 5%, sodium bicarbonate 0.05%, denitrifying bacteria 5% and the balance of water. The denitrifying bacteria are composed of bacillus and pseudomonas in a mass ratio of 1:3.

[0045] Example 9

[0046] The difference from Example 5 is only that: S1. Preparation of materials: The composite carbon source is composed of the following components in mass percentage: glucose 15%, gallic acid 5%, mandelic acid 3%, methanol 11%, sodium lactate 5%, sodium bicarbonate 0.05%, denitrifying bacteria 5% and the balance of water. The denitrifying bacteria are composed of bacillus and pseudomonas in a mass ratio of 1:3.

[0047] Example 10

[0048] The difference from Example 5 is only that: S1. Preparation of materials: The composite carbon source is composed of the following components in mass percentage: glucose 15%, gallic acid 6%, mandelic acid 2%, methanol 11%, sodium lactate 5%, sodium bicarbonate 0.05%, denitrifying bacteria 5% and the balance of water. The denitrifying bacteria are composed of bacillus and pseudomonas in a mass ratio of 1:3.

[0049] Example 11

[0050] The difference from Example 5 is only that: S1. Preparation of materials: The composite carbon source consists of the following components by mass percentage: glucose 15%, gallic acid 7%, mandelic acid 1%, methanol 11%, sodium lactate 5%, sodium bicarbonate 0.05%, denitrifying bacteria 5% and the balance water. The denitrifying bacteria are composed of bacillus and pseudomonas in a mass ratio of 1:3.

[0051] Comparative Example 1

[0052] The difference from Example 1 is only that: sodium lactate is replaced with an equal amount of sodium acetate.

[0053] Comparative Example 2

[0054] The difference from Example 1 is only that: sodium bicarbonate is replaced with an equal amount of sodium phosphate.

[0055] The composite carbon sources obtained from Examples 1 to 11 and Comparative Examples 1 to 2 were used for 2-hour wastewater denitrification treatment according to the dosage of adding 200 mg of the composite carbon source to 1 L of wastewater. Referring to the methods in HJ 537-2009 "Water Quality - Determination of Ammonia Nitrogen - Distillation - Neutralization Titration Method" and GB / T 11894-1989 "Water Quality - Determination of Total Nitrogen - Alkaline Potassium Persulfate Digestion UV Spectrophotometry" respectively, the ammonia nitrogen content in the wastewater before treatment was 39.58 mg / L and the total nitrogen content was 47.71 mg / L. The results are recorded in Table 1.

[0056] Table 1 Ammonia nitrogen content and total nitrogen content in the treated wastewater

[0057]

[0058] As can be seen from Table 1, the composite carbon source provided by the present invention has good denitrification effect. After treatment, the ammonia nitrogen content in the wastewater is below 1.80 mg / L and the total nitrogen content is below 6.33 mg / L. Moreover, the pH of the wastewater treated with the composite carbon source provided by the present invention is close to neutral and the COD is below 12 mg / L, meeting the water quality requirements after purification.

[0059] Compared with Comparative Examples 1 to 2, after treating the wastewater with the composite carbon source obtained by adding sodium lactate and sodium bicarbonate in Example 1, the ammonia nitrogen content and total nitrogen content in the wastewater are lower than those in Comparative Example 1, indicating that lactate as an organic salt and bicarbonate as an inorganic salt can improve the denitrification effect of the composite carbon source.

[0060] After treating the wastewater with the composite carbon source obtained in Example 4, the ammonia nitrogen content and total nitrogen content in the wastewater are lower than those in Example 1, indicating that molasses as a saccharide substance can further improve the denitrification effect of the composite carbon source.

[0061] After treating wastewater with the composite carbon sources obtained in Examples 8 to 11, the ammonia nitrogen content and total nitrogen content in the wastewater are lower than those in Examples 5 to 7, indicating that gallic acid and mandelic acid, as organic acids, and when the mass of gallic acid ≥ the mass of mandelic acid, can further improve the denitrification effect of the composite carbon source.

[0062] After treating wastewater with the composite carbon sources obtained in Examples 9 to 10, the ammonia nitrogen content and total nitrogen content in the wastewater are lower than those in Example 8 and Example 11, indicating that the mass ratio of gallic acid to mandelic acid is 5:3 to 6:2, which can further improve the denitrification effect of the composite carbon source.

[0063] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A composite carbon source for wastewater denitrification, characterized in that: The composition is composed of the following components in percentage by mass: 10% to 20% carbohydrates, 5% to 10% organic acids, 8% to 15% alcohols, 3% to 7% organic salts, 0.01% to 0.1% inorganic salts, 3% to 8% denitrifying bacteria and the remainder water, wherein the organic salt is lactate, and the inorganic salt includes carbonate and / or bicarbonate; The organic acid comprises gallic acid and mandelic acid, and the mass ratio of the gallic acid to the mandelic acid is 5:3-6:

2.

2. A composite carbon source for wastewater denitrification according to claim 1, characterized in that: The sugar substances include one or more of glucose, xylose, fructose and molasses.

3. A composite carbon source for wastewater denitrification according to claim 2, characterized in that: The sugar substance is molasses.

4. A composite carbon source for wastewater denitrification according to claim 1, characterized in that: The alcohol substance includes one or more of methanol, ethanol and ethylene glycol.

5. A composite carbon source for wastewater denitrification according to claim 1, characterized in that: The organic salt is sodium lactate, and the inorganic salt includes sodium carbonate and / or sodium bicarbonate.

6. A composite carbon source for wastewater denitrification according to any one of claims 1 to 5, characterized in that: COD value ≥ 300,000 mg / L, density 1.0~1.26 g / cm at 20℃ 3 .

7. The method for preparing a composite carbon source according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: mixing organic salt with water, sequentially adding sugar substances, organic acids, alcohol substances and inorganic salts and mixing them evenly, and finally adding denitrifying bacteria and mixing them evenly to obtain a composite carbon source.

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