A preparation method of a biological nutrient for electronic wastewater denitrification

Abstract

The application discloses a preparation method of a biological nutrient agent for electronic wastewater denitrification, and comprises the following steps: (1) mixing coffee waste residues and tea waste residues, cleaning and drying, and then grinding into powder; immersing the powder into a sodium hydroxide solution, cleaning and drying after suction filtration, immersing into a hydrochloric acid solution, cleaning and drying after suction filtration, and finally ultrasonic dispersion in water to obtain a composite component A; (2) dissolving small molecule alcohol and acetate in water to obtain a composite component B; (3) ultrasonic dispersion of a chelating agent, sodium hydroxide, inorganic salt, boric acid and cell division element in water to obtain a composite component C; (4) mixing 20-40 mass parts of the composite component A, 30-50 mass parts of the composite component B, 0.01-0.2 mass parts of the composite component C, 0.01-0.1 mass parts of an additive and 0.01-0.2 mass parts of bacteria liquid to obtain the biological nutrient agent. The biological nutrient agent prepared by the method can reduce the dosage of carbon source medicament, shorten the domestication time of a reactor or the recovery time after impact, and greatly improve the denitrification efficiency of the reactor.

Description

Technical Field

[0001] This invention relates to a method for preparing a biological nutrient for denitrification of electronic wastewater. Background Technology

[0002] The electronics industry, such as semiconductors, LCD panels, and photovoltaics, generates nitrogen-containing wastewater (e.g., grinding and cleaning wastewater) during production and processing. This nitrogen-containing wastewater is generally treated through methods such as chemical precipitation, stripping, ion exchange, chemical oxidation, and biochemical treatment. Among these methods, biochemical treatment utilizes microbial metabolism to convert nitrogen in the water into nitrogen gas through ammonification, nitrification, and denitrification. This method is widely used due to its relatively low cost and lack of secondary pollution.

[0003] The biochemical wastewater from the electronics industry suffers from problems such as an imbalanced carbon-to-nitrogen ratio and the impact of silicon and heavy metals on microbial denitrification efficiency. This necessitates the addition of large amounts of carbon sources during denitrification to ensure system denitrification efficiency. Currently, carbon sources used in electronics industry wastewater treatment can be categorized into traditional carbon sources and composite carbon sources. Traditional carbon sources are mostly industrial standards, such as methanol, sodium acetate, and glucose—single-component carbon sources. While these carbon sources are small-molecule organic compounds easily absorbed and utilized by microorganisms, long-term use of single-component carbon sources can lead to a monotonous microbial metabolic pathway, resulting in a decreased system resilience. Furthermore, methanol poses a certain risk due to its flammability and explosiveness; sodium acetate is prone to crystallization, produces large amounts of sludge, has a low COD equivalent, and is relatively expensive; glucose has a slow reaction rate and is prone to sludge bulking. Composite carbon sources offer advantages such as easy absorption by microorganisms, promotion of diversified microbial metabolic pathways, and relatively low cost, making them more suitable for biochemical denitrification of electronics wastewater compared to traditional carbon sources. Common raw materials for composite carbon sources include industrial standards such as alcohols, acids, and sugars, bio-fermentation products, and industrial byproducts. However, existing composite carbon sources have problems such as large dosage during use, no inhibitory effect on influencing factors such as heavy metals, and slow start-up of biochemical systems. Summary of the Invention

[0004] Purpose of the invention: The purpose of this invention is to provide a method for preparing a biological nutrient agent. The biological nutrient agent prepared by this method can reduce the amount of carbon source agent added, shorten the acclimatization time or recovery time after shock to the reactor, and significantly improve the denitrification efficiency of the reactor.

[0005] Technical solution: The preparation method of the biological nutrient agent of the present invention includes the following steps:

[0006] (1) Mix coffee waste and tea waste, wash, dry and grind into powder; first soak the powder in sodium hydroxide solution, filter and wash and dry, then soak in hydrochloric acid solution, filter and wash and dry, and finally ultrasonically disperse in water to obtain composite component A;

[0007] Composite component A was prepared by stepwise acid-base impregnation and ultrasonic treatment of coffee and tea waste. The acid and base processes protonated the coffee and tea waste to release sugars (glucose, fructose, etc.) and nutrients (vitamins, amino acids, etc.) through protonation, attacking polysaccharide glycosidic bonds, promoting peptide bond hydrolysis, and promoting vitamin destabilization. At the same time, ultrasonic treatment promoted the dissolution of the active ingredients into water.

[0008] (2) Dissolve small molecule alcohols and acetates in water to obtain composite component B;

[0009] (3) The chelating agent, sodium hydroxide, inorganic salt, boric acid and cytokinin were ultrasonically dispersed in water to obtain composite component C;

[0010] (4) Mix 20-40 parts by weight of compound component A, 30-50 parts by weight of compound component B, 0.01-0.2 parts by weight of compound component C, 0.01-0.1 parts by weight of adjuvant and 0.01-0.2 parts by weight of bacterial solution to obtain biological nutrient.

[0011] In step (1), the mass ratio of coffee waste and tea waste is 0.19 to 0.43:1.

[0012] In step (1), the mass concentration of the sodium hydroxide solution is 5-10%, the powdered material is immersed in the sodium hydroxide solution for 8-12 hours, the drying temperature is 60-100℃, and the drying time is 4-6 hours; the mass concentration of the hydrochloric acid solution is 5-10%, the powdered material is immersed in the hydrochloric acid solution for 8-12 hours, the drying temperature is 60-100℃, and the drying time is 4-6 hours.

[0013] In step (1), the powdered material is ultrasonically dispersed in deionized water at a solid-liquid ratio of 15-100 g / L, and the ultrasonic treatment time is 6-12 h to obtain composite component A.

[0014] In step (2), the small molecule alcohol is ethylene glycol, and the acetate is sodium acetate; in the composite component B, the mass concentration of the small molecule alcohol is 35-38%, and the mass concentration of the acetate is 25-30%.

[0015] In step (3), the chelating agent is disodium ethylenediaminetetraacetate; the inorganic salt is a mixture of zinc sulfate, ammonium molybdate, calcium chloride, ferrous sulfate, magnesium sulfate, copper sulfate, manganese chloride, and cobalt chloride in a mass ratio of 2-3:11-12:2-3:12-13:3-4:2-3:5-6:2-3; in the composite component C, the mass concentration of the chelating agent is 2-4%, the mass concentration of sodium hydroxide is 0.1-0.5%, the mass concentration of the inorganic salt is 0.2-0.5%, the mass concentration of boric acid is 0.01%, and the mass concentration of cytokinin is 0.1-0.3%.

[0016] In step (3), the ultrasonic parameters are set to power 200-300W, frequency 20-30kHz, and ultrasonic time 2.5-3.5h.

[0017] In step (4), the adjuvant is sodium dodecylbenzenesulfonate, and the bacterial solution is Pseudomonas balearica FX-1 bacterial solution (Chinese Patent 201810310468.9 "A Pseudomonas balearica FX-1 and its application"), with a bacterial concentration of 10. 9 cfu / ml.

[0018] In step (4), the COD concentration in the biological nutrient is 300,000 to 500,000 mg / L.

[0019] The carbohydrates in component A and component B provide electrons and energy for the denitrifying bacteria in the reactor. For example, glucose enters the cell via active transport and is converted into pyruvate via glycolysis (EMP), then enters the tricarboxylic acid cycle (TCA) or other metabolic pathways. Ethylene glycol is converted into glycolic acid by enzymes such as alcohol dehydrogenase and aldehyde dehydrogenase, entering the TCA cycle to replenish the body. Metabolites such as reduced nicotinamide adenine dinucleotide (NADH) and reduced flavin adenine dinucleotide (FADH2) transfer electrons and energy to reduce nitrate nitrogen. The amino acids and vitamins in component A and component C provide energy for the microorganisms in the reactor. Growth factors enhance microbial enzyme activity, maintain cell structure and function, and participate in electron transfer, thereby promoting the reduction of nitrate nitrogen through microbial metabolism. They also have a chelating effect, inhibiting heavy metals that affect biochemical factors, thus enhancing the system's resistance to shocks and shortening the system's recovery time after startup or shock. Additives reduce liquid surface tension, weakening the interaction forces between carbon source particles, effectively preventing aggregation, enhancing the dispersibility of carbon sources in water, promoting mass transfer, and thus improving their utilization rate. Bacterial solutions strengthen denitrifying bacteria, increasing the number and activity of denitrifying bacteria in the system, improving carbon source utilization, and thus increasing denitrification efficiency.

[0020] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: The biological nutrient agent prepared by the present invention can not only ensure the efficient denitrification of the system, but also solve the problems of large carbon source agent dosage, long acclimatization time, and poor system shock resistance of existing biological nutrient agents; in addition, it can help microorganisms grow and reproduce rapidly when dealing with the start-up of the biochemical system, shortening the acclimatization period by more than 30%; when dealing with the impact on the biochemical system, it can help microorganisms recover quickly, shortening the recovery time by more than 25%; when the system is running stably, it can reduce the dosage by more than 30%; the method of the present invention can also realize the resource utilization of solid waste. Detailed Implementation

[0021] Example 1

[0022] The preparation method of the biological nutrient agent of the present invention includes the following steps:

[0023] (1) 100g of coffee waste and 312.5g of tea waste (mass ratio 0.32:1) were rinsed with deionized water, dried in an oven at 80℃ for 5h, and then ground into powder (200 mesh); the powder was soaked in 5wt.% sodium hydroxide solution for 10h, filtered, rinsed with deionized water, and dried in an oven at 80℃ for 5h; then soaked in 5wt.% hydrochloric acid solution for 10h, filtered, rinsed with deionized water, and dried in an oven at 80℃ for 5h; finally, the powder was ultrasonically treated in deionized water at a solid-liquid ratio of 80g / L for 8h to obtain composite component A;

[0024] (2) Mix 450g of ethylene glycol and 296g of sodium acetate, add them to deionized water and stir for 1.5h to obtain composite component B; in composite component B, the mass concentration of ethylene glycol is 38% and the mass concentration of sodium acetate is 25%.

[0025] (3) 1.2g disodium ethylenediaminetetraacetate, 0.16g sodium hydroxide, 0.008g zinc sulfate, 0.044g ammonium molybdate, 0.008g calcium chloride, 0.048g ferrous sulfate, 0.008g copper sulfate, 0.012g magnesium sulfate, 0.02g manganese chloride, 0.008g cobalt chloride, 0.004g boric acid, and 0.04g cytokinin were added to deionized water for ultrasonic chelation. The cavitation effect of ultrasound increased the collision frequency and energy of reactant molecules, thereby promoting the accelerated formation of stable complexes. The ultrasonic parameters were set as follows: power 200W, frequency 25kHz, and ultrasonic... After 3 hours, composite component C was obtained. In composite component C, the mass concentrations of disodium ethylenediaminetetraacetate (EDTA) were 3%, sodium hydroxide (0.4%), zinc sulfate (0.02%), ammonium molybdate (0.11%), calcium chloride (0.02%), ferrous sulfate (0.12%), copper sulfate (0.02%), magnesium sulfate (0.03%), manganese chloride (0.05%), cobalt chloride (0.02%), boric acid (0.01%), and cytokinin (0.1%).

[0026] (4) Mix 35 parts by weight of compound component A, 46 parts by weight of compound component B, 0.2 parts by weight of compound component C, 0.06 parts by weight of sodium dodecylbenzenesulfonate, and 0.1 parts by weight of Pseudomonas balearica FX-1 bacterial suspension (bacterial concentration 10). 9 Mix (cfu / ml) and stir for 2.5 h to obtain the biological nutrient solution; the COD of the biological nutrient solution is 350000 mg / L.

[0027] The biological nutrient agent prepared in Example 1 was used to treat electronic wastewater, which originated from a panel factory. The initial water quality indicators were as follows: total nitrogen concentration of 100 mg / L, COD of 30 mg / L, and pH of 7.5. The specific method for treating the above wastewater was as follows:

[0028] In the denitrification process, biological nutrients were added to the anoxic tank (the sludge was acclimated and the sludge concentration in the anoxic tank was 3400 mg / L). The carbon-to-nitrogen ratio was 3.5:1, the denitrification retention time was 4 hours, and the dissolved oxygen was controlled at 0.2 mg / L with slow stirring. After treatment, the total nitrogen concentration was 6.79 mg / L, and the total nitrogen removal rate reached 93.21%, achieving efficient denitrification.

[0029] Example 2

[0030] The biological nutrient agent prepared in Example 1 was used to treat electronic wastewater, which originated from a panel factory. The initial water quality indicators were as follows: total nitrogen concentration of 100 mg / L, COD of 30 mg / L, and pH of 7.5. The specific method for treating the above wastewater was as follows:

[0031] In the anoxic tank (the sludge was unacclimated and the sludge concentration in the anoxic tank was 2300 mg / L), two batches were acclimated. The parameters for each batch were set with a carbon-to-nitrogen ratio of 5:1 and a denitrification retention time of 4 hours. After treatment, the total nitrogen concentration was 8.91 mg / L, and the total nitrogen removal rate reached 91.09%.

[0032] Example 3

[0033] The biological nutrient agent prepared in Example 1 was used to treat electronic wastewater, which originated from a panel factory. The initial water quality indicators were as follows: total nitrogen concentration of 100 mg / L, COD of 30 mg / L, and pH of 7.5. The specific method for treating the above wastewater was as follows:

[0034] In the anoxic tank (the sludge was activated sludge inhibited by the bactericide, and the sludge concentration in the anoxic tank was 1900 mg / L), three batches were acclimated. The parameters for each batch were set with a carbon-to-nitrogen ratio of 5:1 and a denitrification retention time of 4 hours. After treatment, the total nitrogen concentration was 8.75 mg / L, and the total nitrogen removal rate reached 91.25%.

[0035] Comparative Examples 1-9

[0036] The total nitrogen concentration of the wastewater was 100 mg / L, and the initial pH was 7.5. Nine comparative experiments were conducted (referred to as Comparative Examples 1 to 9). The sludge used in Comparative Examples 1 to 3 was the acclimated sludge from Example 1; the sludge used in Comparative Examples 4 to 6 was the unacclimated sludge from Example 2; and the sludge used in Comparative Examples 7 to 9 was the sludge contaminated with bactericide from Example 3. The wastewater flowed into an anoxic tank, the stirring rate was 80 rpm, and the DO was maintained at 0.2 mg / L. Sodium acetate (Comparative Examples 1, 4, 7), alcohol composite carbon source (Comparative Examples 2, 5, 8), and kitchen waste fermentation carbon source (Comparative Examples 3, 6, 9) were added to Comparative Examples 1 to 9, respectively. Comparative Examples 1 to 3 were acclimated once, with a carbon-to-nitrogen ratio of 5:1 per batch; Comparative Examples 4 to 6 were acclimated three times, with a carbon-to-nitrogen ratio of 5:1 per batch; and Comparative Examples 7 to 9 were acclimated four times, with a carbon-to-nitrogen ratio of 5:1 per batch. The denitrification retention time was 4 hours. The treatment results are shown in Table 1.

[0037] Table 1 shows the treatment effects of Examples 1-3 and Comparative Examples 1-9 on wastewater containing total nitrogen.

[0038]

[0039] The comparison shows that the biological nutrient agent prepared by the present invention can effectively reduce the amount of carbon source agent added while ensuring efficient removal of total nitrogen; and has better total nitrogen removal performance in the process of starting up or repairing a biochemical system after impact.

[0040] Comparative Examples 10–14

[0041] The electronic wastewater originated from a panel factory. The initial water quality indicators were as follows: total nitrogen concentration 100 mg / L, COD 30 mg / L, initial pH = 7.5. Five comparative experiments were conducted (referred to as Comparative Examples 10-14). In Comparative Example 10, biological nutrient a was used by replacing compound component A in the nutrient solution of Example 1 with glucose of equal COD equivalent. In Comparative Example 11, biological nutrient b was used by replacing compound component B in the nutrient solution of Example 1 with glycerol of equal COD equivalent. In Comparative Example 12, biological nutrient c was used by replacing compound component C in the nutrient solution of Example 1 with deionized water. In Comparative Example 13, biological nutrient d was used by replacing sodium dodecylbenzenesulfonate in the nutrient solution of Example 1 with deionized water. In Comparative Example 14, biological nutrient e was used by replacing *Pseudomonas bariensis* in the nutrient solution of Example 1 with... The balearica FX-1 bacterial solution was replaced with deionized water; the sludge used in Comparative Examples 10-14 was the acclimated sludge from Example 1. The wastewater flowed into the anoxic tank, the stirring rate was 80 rpm, the DO was maintained at 0.2 mg / L, Comparative Examples 10-14 were acclimated once, the carbon-nitrogen ratio of each batch was 3.5:1, the denitrification retention time was 4 h, and the treatment results are shown in Table 2.

[0042] Table 2 shows the wastewater treatment effects of Example 1 and Comparative Examples 10-14.

[0043]

[0044] The comparison shows that the formulation of the biological nutrient agent prepared in this invention can ensure higher total nitrogen removal efficiency while maintaining a low dosage.

Claims

1. A method for preparing a biological nutrient agent for denitrification of electronic wastewater, characterized in that, Includes the following steps: (1) After rinsing 100g of coffee waste and 312.5g of tea waste with deionized water, place them in an oven and dry them at 80℃ for 5h, then grind them into 200 mesh powder; immerse the powdered material in 5wt.% sodium hydroxide solution for 10h, filter it, rinse it with deionized water, and dry it in an oven at 80℃ for 5h; then immerse it in 5wt.% hydrochloric acid solution for 10h, filter it, rinse it with deionized water, and dry it in an oven at 80℃ for 5h; finally, place the powdered material in deionized water at a solid-liquid ratio of 80g / L and sonicate it for 8h to obtain composite component A; (2) Mix 450g of ethylene glycol and 296g of sodium acetate, add them to deionized water and stir for 1.5h to obtain composite component B; (3) 1.2g disodium ethylenediaminetetraacetate, 0.16g sodium hydroxide, 0.008g zinc sulfate, 0.044g ammonium molybdate, 0.008g calcium chloride, 0.048g ferrous sulfate, 0.008g copper sulfate, 0.012g magnesium sulfate, 0.02g manganese chloride, 0.008g cobalt chloride, 0.004g boric acid and 0.04g cytokinin were added to deionized water and ultrasonically chelated. The ultrasonic parameters were set to power 200 W, frequency 25 kHz and ultrasonic time 3 h to obtain composite component C. (4) Mix 35 parts by weight of composite component A, 46 parts by weight of composite component B, 0.2 parts by weight of composite component C, 0.06 parts by weight of sodium dodecylbenzenesulfonate, and 0.1 parts by weight of *Pseudomonas bariensis* FX-1 bacterial suspension, and stir for 2.5 h to obtain a biological nutrient solution; the COD of the biological nutrient solution is 350,000 mg / L; wherein, the concentration of *Pseudomonas bariensis* FX-1 bacterial suspension is 10 9 CFU / mL.

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