A method for simultaneous nitrification and denitrification and chromium remediation of high ammonia-nitrogen wastewater based on a microorganism-promoter combination

Abstract

The application discloses a high-ammonia-nitrogen wastewater simultaneous nitrification and denitrification and chromium remediation method based on a microorganism-promoter combination. 12 The combination is composed of simultaneous nitrification and denitrification bacteria and sodium azide (NaN3), alanine and dodecamolybdenum phosphate (PMo 12 ) and is used for detoxifying dissolved heavy metal chromium and improving denitrification efficiency. The method is to culture SND simultaneous short-cut nitrification and denitrification biological bacteria under aerobic conditions, inoculate the biological bacteria into a high-chromium solution, add biological promoters, promote the growth of microorganisms and the conversion of nitrogen, continuously receive and provide electrons in a reversible oxidation-reduction process, thereby reducing the total activation energy of the reaction and efficiently detoxifying heavy metal chromium. The microorganism-promoter combination technology obtained in this way can not only realize efficient simultaneous nitrification and denitrification in high-ammonia-nitrogen wastewater, but also maintain the biological activity of the SND bacteria in a high-chromium environment, thereby providing reliable technical support for efficient chromium removal and toxicity remediation of high-ammonia-nitrogen wastewater.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology and relates to a method for the simultaneous nitrification, denitrification, and chromium remediation of high ammonia nitrogen wastewater based on a combination of microorganisms and promoters. Background Technology

[0002] Microbial denitrification is widely used in aquaculture wastewater treatment due to its advantages such as economy, high efficiency, and no secondary pollution. Among them, SND bacteria can perform heterotrophic simultaneous nitrification and denitrification of ammonia nitrogen, directly converting ammonia nitrogen into gaseous nitrogen products. This effectively avoids the conflicting requirements of traditional nitrifying and denitrifying bacteria for carbon sources, dissolved oxygen, and alkalinity, greatly improving denitrification efficiency. However, in practical applications, wastewater is often complex, containing not only high concentrations of ammonia nitrogen but also numerous toxic and harmful substances, such as heavy metals. For example, in livestock farming, unused livestock feed and metabolites result in a large amount of nitrogenous pollutants in the wastewater, especially ammonia nitrogen, with concentrations reaching 800–2200 mg / L. Furthermore, due to heavy metal pollution in the farming environment and the addition of heavy metal-containing additives during the farming process, the nitrogen in the wastewater often combines with heavy metals. Studies have shown that chromium is an essential nutrient for the growth and development of livestock and poultry. Adding chromium to livestock and poultry feed has a positive impact on the growth, development, immunity, reproduction, and carcass quality of animals such as chickens, ducks, cattle, sheep, and pigs. However, the absorption rate of chromium by livestock and poultry is low (approximately 10%–25% for organic chromium and 1%–3% for inorganic chromium). Therefore, most of the chromium ingested by livestock and poultry is excreted into livestock wastewater, leading to potential chromium pollution in this wastewater. Furthermore, landfill leachate is also a common high-ammonia-nitrogen organic wastewater, with ammonia nitrogen concentrations reaching 800–1500 mg / L. Due to the complex sources of landfill leachate, especially the discharge of industrial waste, the content of various heavy metals in it is relatively high. Chromium is a typical heavy metal pollutant in landfill leachate and is also one of the metals with high biotoxicity and significant pollutant activity.

[0003] Due to the high biotoxicity and high mobility of Cr(VI), it is usually in anionic form (such as CrO4). 2- Cr2O7 2- The presence of Cr(VI) can inactivate enzymes and disrupt the oxidative balance within cells by directly binding to them and inducing the generation of reactive oxygen species (ROS). Furthermore, Cr(VI) inhibits the secretion of key intracellular electron transfer carriers (nicotinamide adenine dinucleotide (NADH), flavin mononucleotide (FMN), flavin adenine dinucleotide (FAD), and cytochrome c (Cyt.c)) in SND bacteria, leading to a reduction in microbial detoxification pathways. Therefore, Cr(VI) severely limits the biological activity and treatment efficiency of SND bacteria in high-ammonia nitrogen wastewater.

[0004] Given the problems mentioned above, developing a microbial promotion technology that combines biological toxicity removal and treatment efficiency enhancement is a major challenge for the high ammonia nitrogen wastewater treatment industry and a key to technological upgrading. Summary of the Invention

[0005] In response to the high ammonia nitrogen content and excessive chromium content in wastewater, and the high biotoxicity of wastewater due to the difficulty in migration and degradation of heavy metals and their easy accumulation, a method for simultaneous nitrification, denitrification and chromium remediation of high ammonia nitrogen wastewater based on a combination of microorganisms and promoters is disclosed to address the problem of low bioremediation activity under high chromium conditions.

[0006] This invention cultivates SND (Synthetic Nitrifying and Denitrifying) microbial strains under aerobic conditions and inoculates them in a high-chromium solution. By adding a biological promoter, the microbial growth and nitrogen conversion are promoted. The microorganisms continuously accept and provide electrons in the reversible redox process, thereby reducing the total activation energy of the reaction and efficiently detoxifying the heavy metal chromium.

[0007] This invention provides a novel method for the biological treatment of wastewater high in heavy metals and ammonia nitrogen through in-depth research on electron transfer behavior and toxicity detoxification mechanisms. This method enables SND bacteria to maintain biological activity and achieve efficient chromium removal under high chromium conditions, fundamentally solving the problem of reduced activity during the biological treatment of high-chromium wastewater.

[0008] The objective of this invention is achieved through the following technical solution:

[0009] A method for simultaneous nitrification, denitrification, and chromium remediation of high-ammonia nitrogen wastewater based on a microbial-promoter combination, characterized by comprising the following steps:

[0010] 1) Pick two loops of denitrifying paracoccus and transfer them to the nutrient solution for independent culture. Inoculate them into the proliferation medium at a volume ratio of 5-15% and culture them independently. Centrifuge to obtain the logarithmic growth phase cells of the strain.

[0011] 2) Wash the logarithmic growth phase cells with phosphate buffer, centrifuge, and then prepare a highly concentrated bacterial suspension with sterile water;

[0012] 3) Prepare OD from the "highly concentrated bacterial suspension" obtained in step 2) using sterile water. 600 A bacterial suspension of 1.0–1.5% was inoculated into chromium-containing, high-ammonia-nitrogen wastewater at a ratio of 20–25% (volume ratio) and cultured until the solution OD reached a certain level. 600 When the pH reaches 1.0–1.2, a biological promoter is added, comprising 0.02–0.05 mmol / L NaN3, 0.05–0.1 mmol / L alanine, and 0.05–0.1 mmol / L PMo. 12 The removal is completed by reacting in a shaker for 48–96 hours;

[0013] Furthermore, the denitrifying paracoccus mentioned in step 1) was purchased from the Guangdong Provincial Microbial Culture Collection Center, with the catalog number GDMCC 1.335.

[0014] Furthermore, the culture conditions described in step 1) are: cultured at 30-35℃ for 1-3 days.

[0015] Further, the main components of the proliferation culture medium in step 1) are: casein 20.0 g / L, potassium dihydrogen phosphate 3.0 g / L, glucose 3.0 g / L, sodium chloride 5.0 g / L, and the remainder is water.

[0016] Further, the centrifugation process in step 2) is performed at 8000-10000 rpm for 3-5 minutes.

[0017] Furthermore, the Cr(VI) content in the chromium contaminated solution described in step 3) is not higher than 12 mg / L.

[0018] Further, the bio-promoter in step 3) comprises 0.02–0.05 mmol / L NaN3, 0.05–0.1 mmol / L alanine, and 0.05–0.1 mmol / L PMo. 12 .

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1) The simultaneous nitrification, denitrification and chromium remediation technology for high ammonia nitrogen wastewater established by using microorganism-promoter combination can improve the biological activity of microorganisms in high chromium environment, enhance electron transfer in microbial metabolism and detoxify heavy metal toxicity.

[0021] 2) It has both denitrification and chromium removal functions. Simultaneous denitrification and chromium removal can save time and cost in wastewater treatment and give full play to the wastewater treatment capacity of SND bacteria.

[0022] 3) The treatment process is simple to operate and has low processing costs. The added accelerator can play a role at a low concentration, reducing the cost of chemical input.

[0023] 4) No alkalinity addition is required. Nitrification is an acid-producing process, while denitrification is an alkali-producing process. Simultaneous short-cut nitrification-denitrification denitrification technology can effectively maintain pH stability in the reactor. Attached Figure Description

[0024] Figure 1a NH4 is the nitrification-denitrification and chromium remediation process of the microbial-promoter combination in Example 1. + -N, NO3 - Graph showing the changes in -N and Cr(VI) concentrations;

[0025] Figure 1b NH4 is the nitrification-denitrification and chromium remediation process of the microbial-promoter combination in Example 1. + -N, NO3 - -N, TN and Cr(VI) removal efficiency diagram;

[0026] Figure 2a NH4 is the nitrification-denitrification and chromium remediation process of the microbial-promoter combination in Example 2. + -N, NO3 - Graph showing the changes in -N and Cr(VI) concentrations;

[0027] Figure 2b NH4 is the nitrification-denitrification and chromium remediation process of the microbial-promoter combination in Example 2. + -N, NO3 - -N, TN and Cr(VI) removal efficiency diagram;

[0028] Figure 3a The NH4+ used in the simultaneous nitrification-denitrification and chromium remediation process of the microbial-promoter combination in Experiment 1 of Example 3 is... + -N, NO3 - Graph showing the changes in -N and Cr(VI) concentrations;

[0029] Figure 3b The NH4+ used in the simultaneous nitrification-denitrification and chromium remediation process of the microbial-promoter combination in Experiment 1 of Example 3 is... + -N, NO3 - Removal efficiency diagrams for -N, TN, and Cr(VI).

[0030] Figure 4a NH4+ is used in the simultaneous nitrification-denitrification and chromium remediation process of the microbial-promoter combination in the comparative experiment of Example 3. + -N, NO3 - Graph showing the changes in -N and Cr(VI) concentrations;

[0031] Figure 4b NH4+ is used in the simultaneous nitrification-denitrification and chromium remediation process of the microbial-promoter combination in the comparative experiment of Example 3. + -N, NO3 - Removal efficiency diagrams for -N, TN, and Cr(VI). Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described below in conjunction with embodiments and accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0033] This invention addresses the characteristics of wastewater with high nitrogen content, excessive chromium content, and high biotoxicity. To overcome the limitations of chromium on biological denitrification technology, it discloses a method for simultaneous nitrification and denitrification of high ammonia nitrogen wastewater and chromium remediation based on a combination of microorganisms and promoters.

[0034] Example 1

[0035] 1) Two loops of *Paracoccus denitrificans* (purchased from Guangdong Provincial Microbial Culture Collection Center, catalog number: GDMCC 1.335) were transferred to nutrient solution (the main components of which are: 10.0 g / L tryptone, 10.0 g / L NaCl, 5.0 g / L yeast extract, pH 7.2, diluted with water to make 1 L of nutrient solution) and cultured independently. Then, 15% of the culture was inoculated into proliferation medium (the main components of which are: 20.0 g / L casein, 3.0 g / L potassium dihydrogen phosphate, 3.0 g / L glucose, 5.0 g / L sodium chloride, diluted with water to make 2 L of proliferation medium) and cultured independently. The culture was then centrifuged (8000 rpm, 5 min) to obtain the logarithmic growth phase cells of the strain.

[0036] 2) The logarithmic growth phase cells were washed with phosphate buffer (the main components of which are: sodium chloride 8.0 g / L, dipotassium hydrogen phosphate trihydrate 7.98 g / L, potassium dihydrogen phosphate 2.04 g / L, and water was added to make 1 L of phosphate buffer), centrifuged (10000 rpm, 5 min), and then prepared into a highly concentrated bacterial suspension with sterile water.

[0037] 3) Prepare OD from the highly concentrated bacterial suspension using sterile water. 600 A bacterial suspension of 1.5% was inoculated into chromium-containing wastewater at a ratio of 25% (v / v) and cultured until the solution OD reached a certain level. 600 When the concentration reaches 1.2, add 0.04 mmol / L NaN3, 0.08 mmol / L alanine, and 0.05 mmol / L PMo. 12 ;

[0038] The technology described in this embodiment was used to treat 1L of industrial wastewater (influent water quality: ammonia nitrogen 265.19mg / L, total nitrogen 279.52mg / L, Cr(VI) 10.95mg / L) from... Figure 1a It can be seen that the effluent from the system contains only 21.53 mg of NH4. + -N / L, 0.97mg NO3 - -N / L, 15.57mg NO2 - -N / L, 38.06 mg TN / L, 1.87 mg Cr(VI) / L; Meanwhile, if Figure 1b As shown, NH4 +The removal efficiency of -N was 91.88%, the removal efficiency of TN was 86.38%, the removal efficiency of SND was 99.09%, and the removal rate of Cr(VI) was 82.90%.

[0039] Example 2

[0040] 1) Two loops of denitrified paracocci (purchased from Guangdong Provincial Microbial Culture Collection Center, catalog number: GDMCC 1.335) were transferred to nutrient solution (the main components of which are: tryptone 10.0 g / L, NaCl 10.0 g / L, yeast extract powder 5.0 g / L, pH 7.2, diluted with water to make 1 L of nutrient solution) and cultured independently. Then, 10% of the culture was inoculated into proliferation medium (the main components of which are: casein 20.0 g / L, potassium dihydrogen phosphate 3.0 g / L, glucose 3.0 g / L, sodium chloride 5.0 g / L, diluted with water to make 3 L of proliferation medium) and cultured independently. The culture was then centrifuged (6000 rpm, 5 min) to obtain the logarithmic growth phase cells of the strain.

[0041] 2) The logarithmic growth phase cells were washed with phosphate buffer (the main components of which are: sodium chloride 8.0 g / L, dipotassium hydrogen phosphate trihydrate 7.98 g / L, potassium dihydrogen phosphate 2.04 g / L, and water was added to make 1.5 L of phosphate buffer), centrifuged (8000 rpm, 5 min), and then prepared into a highly concentrated bacterial suspension with sterile water.

[0042] 3) Prepare OD from the highly concentrated bacterial suspension using sterile water. 600 A bacterial suspension of 1.2 was inoculated into chromium-containing aquaculture wastewater at a ratio of 20% (volume ratio) and cultured until the solution OD reached a certain level. 600 When the concentration reaches 1.0, add 0.02 mmol / L NaN3, 0.05 mmol / L alanine, and 0.05 mmol / L PMo. 12 The removal was completed by reacting in a shaker (150 rpm, 30 ℃) for 96 h;

[0043] The technology described in this embodiment was used to treat 1.5L of aquaculture wastewater (influent water quality: ammonia nitrogen 541.47mg / L, total nitrogen 554.71mg / L, Cr(VI) 4.13mg / L) from... Figure 2a It can be seen that the effluent from the system contains only 49.40 mg of NH4. + -N / L, 7.66mg NO3 - -N / L, 9.77mg NO2 - -N / L, 89.69 mg TN / L, 0.76 mg Cr(VI) / L; and simultaneously... Figure 2b As shown, NH4 +The removal efficiency of -N was 90.88%, the removal efficiency of TN was 87.95%, the removal efficiency of SND was 99.15%, and the removal rate of Cr(VI) was 81.49%.

[0044] Example 3

[0045] Experiment 1: 1) Two loops of *Paracoccus denitrificans* (purchased from Guangdong Provincial Microbial Culture Collection Center, catalog number: GDMCC 1.335) were transferred to a nutrient solution (the main components of which are: 10.0 g / L tryptone, 10.0 g / L NaCl, 5.0 g / L yeast extract, pH 7.2, diluted with water to make 1 L of nutrient solution) and cultured independently. 5% of the culture was then inoculated into a proliferation medium (the main components of which are: 20.0 g / L casein, 3.0 g / L potassium dihydrogen phosphate, 3.0 g / L glucose, 5.0 g / L sodium chloride, with the remainder being water diluted with water to make 3 L of proliferation medium) and cultured independently. The culture was then centrifuged (8000 rpm, 5 min) to obtain the logarithmic growth phase cells of the strain.

[0046] 2) The logarithmic growth phase cells were washed with phosphate buffer (the main components of which are: sodium chloride 8.0 g / L, dipotassium hydrogen phosphate trihydrate 7.98 g / L, potassium dihydrogen phosphate 2.04 g / L, and water was added to make 1.5 L of phosphate buffer), centrifuged (7000 rpm, 6 min), and then prepared into a highly concentrated bacterial suspension with sterile water.

[0047] 3) Prepare OD from the highly concentrated bacterial suspension using sterile water. 600 A bacterial suspension of 1.1 was inoculated into chromium-containing aquaculture wastewater at a ratio of 20% (volume ratio) and cultured until the solution OD reached a certain level. 600 When the concentration reaches 1.0, add 0.05 mmol / L NaN3, 0.1 mmol / L alanine, and 0.1 mmol / L PMo. 12 The removal was completed by reacting in a shaker (150 rpm, 35 ℃) for 72 h;

[0048] The technology described in this embodiment was used to treat 1.5L of landfill leachate (influent water quality: ammonia nitrogen 307.82mg / L, total nitrogen 321.47mg / L, Cr(VI) 8.67mg / L) from... Figure 3a It can be seen that the effluent from the system contains only 36.73 mg of NH4. + -N / L, 0.74mg NO3 - -N / L, 25.47mg NO2 - -N / L, 62.94 mg TN / L, 2.44 mg Cr(VI) / L; and simultaneously... Figure 3b As shown, NH4 +The removal efficiency of -N was 88.07%, the removal efficiency of TN was 80.42%, the removal efficiency of SND was 95.37%, and the removal rate of Cr(VI) was 71.85%.

[0049] Comparative Experiment: The experimental method was the same as in Experiment 1, except that 1-naphthaleneacetic acid, a commonly used growth promoter, was used as the microbial growth promoter at a concentration of 0.25 mmol / L. According to the experimental results, the effluent from this comparative experimental system contained 66.32 mg of NH4+. + -N / L, 0.30mg NO3 - -N / L, 32.78mg NO2 - -N / L, 56.90 mg TN / L, 3.84 mg Cr(VI) / L; Meanwhile, if Figure 4b As shown, NH4 + The removal efficiency of -N was 61.97%, the removal efficiency of TN was 56.90%, the removal efficiency of SND was 89.04%, and the removal rate of Cr(VI) was 55.71%.

[0050] As can be seen from Figures 3 and 4, compared with the traditional growth promoter 1-naphthaleneacetic acid, the promoter used in this invention effectively improves the wastewater treatment efficiency.

[0051] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for simultaneous nitrification, denitrification, and chromium remediation of high-ammonia nitrogen wastewater based on a microbial-promoter combination, characterized in that, Includes the following steps: 1) Pick two loops of denitrifying paracoccus and transfer them to the nutrient solution for independent culture. Inoculate them into the proliferation medium at a volume ratio of 5-15% and culture them independently. Centrifuge to obtain the logarithmic growth phase cells of the strain. 2) Wash the logarithmic growth phase cells with phosphate buffer, centrifuge, and then prepare a highly concentrated bacterial suspension with sterile water; 3) Prepare OD from the highly concentrated bacterial suspension obtained in step 2) using sterile water. 600 A bacterial suspension of 1.0–1.5 μL was inoculated into chromium-containing wastewater at a volume ratio of 20–25%, and cultured until the solution OD reached a certain level. 600 When the concentration reaches 1.0–1.2, a biological promoter is added, and the removal is completed by reaction in a shaker; the biological promoter includes 0.02–0.05 mmol / L NaN3, 0.05–0.1 mmol / L alanine, and 0.05–0.1 mmol / L PMo. 12 .

2. The method for simultaneous nitrification, denitrification, and chromium remediation of high-ammonia nitrogen wastewater based on a microbial-promoter combination according to claim 1, characterized in that, In step 1), the denitrifying paracoccus was purchased from the Guangdong Provincial Microbial Culture Collection Center, and its catalog number is: GDMCC 1.

335.

3. The method for simultaneous nitrification, denitrification, and chromium remediation of high-ammonia nitrogen wastewater based on a microbial-promoter combination according to claim 1, characterized in that, In step 1), the culture conditions are all: cultured at 30-35℃ for 1-3 days.

4. The method for simultaneous nitrification, denitrification, and chromium remediation of high-ammonia nitrogen wastewater based on a microbial-promoter combination according to claim 1, characterized in that, In step 1), the main components of the proliferation culture medium are: casein 20.0 g / L, potassium dihydrogen phosphate 3.0 g / L, glucose 3.0 g / L, sodium chloride 5.0 g / L, and the remainder is water.

5. The method for simultaneous nitrification, denitrification, and chromium remediation of high-ammonia nitrogen wastewater based on a microbial-promoter combination according to claim 1, characterized in that, In step 1), the centrifugation process is performed at 5000-8000 rpm for 5-8 minutes.

6. The method for simultaneous nitrification, denitrification, and chromium remediation of high-ammonia nitrogen wastewater based on a microbial-promoter combination according to claim 1, characterized in that, In step 2), the washing is performed 1 to 3 times.

7. The method for simultaneous nitrification, denitrification, and chromium remediation of high-ammonia nitrogen wastewater based on a microbial-promoter combination according to claim 1, characterized in that, In step 2), the centrifugation process is performed at 8000-10000 rpm for 3-5 minutes.

8. The method for simultaneous nitrification, denitrification, and chromium remediation of high-ammonia nitrogen wastewater based on a microbial-promoter combination according to claim 1, characterized in that, In step 3), the Cr(VI) content in the wastewater is not higher than 15 mg / L.

9. The method for simultaneous nitrification, denitrification, and chromium remediation of high-ammonia nitrogen wastewater based on a microbial-promoter combination according to claim 1, characterized in that, The reaction time in the shaker is 48–96 hours.

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