Method for high-efficiency treatment of ammonia-oximation high-nitrogen wastewater by microalgae

Abstract

The present application relates to a kind of microalgae high-efficiency treatment of ammonia oximation high nitrogen-containing wastewater method, comprising the following steps: microalgae is inoculated in the cultivation system including ammonia oximation wastewater containing ammonia nitrogen and nitrate nitrogen and is cultivated.By the growth of microalgae in ammonia oximation wastewater containing ammonia nitrogen and nitrate nitrogen, the pollutants in ammonia oximation wastewater are effectively removed as the nutrient required for microalgae propagation.The method of the present application can effectively remove ammonia nitrogen and nitrate nitrogen in ammonia oximation wastewater, create high-value microalgae biomass, realize the comprehensive development and utilization of resources;Second, it can simplify the wastewater treatment process, save the operation cost of wastewater treatment;Third, it can avoid the generation of toxic and harmful ammonia gas during wastewater concentration treatment, reduce the physical harm of on-site workers and avoid environmental pollution, so as to achieve the multiple values of high efficiency, economy, environmental protection and safety, especially suitable for high ammonia nitrogen and nitrate nitrogen process wastewater.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wastewater treatment, and particularly relates to a method for efficiently treating high-nitrogen oxamidated wastewater by microalgae. BACKGROUND

[0002] With the rapid development of modern industry, water pollution problems are becoming increasingly serious. Among them, nitrogen-containing wastewater, especially high-concentration ammonia nitrogen and nitrate nitrogen wastewater, is seriously harmful to the environment and can easily cause water eutrophication, water aging and other serious ecological disasters.

[0003] The cyclohexanone oximation device is the largest source of nitrogen flow in the caprolactam production process, and the nitrogen content accounts for more than 60%. The more mainstream process currently used in the industry is to use biological denitrification method for treatment. The working principle is to use aerobic nitrifying bacteria to convert ammonia nitrogen into nitrate nitrogen or nitrite nitrogen, and then use anaerobic denitrifying bacteria to reduce nitrate nitrogen or nitrite nitrogen into nitrogen gas to complete the removal of nitrogen in wastewater. Although this method can effectively remove nitrogen in wastewater, it has obvious defects, such as inability to effectively recycle nitrogen to create high-value-added products, high cost of wastewater treatment, and harsh growth conditions for nitrifying bacteria / denitrifying bacteria. Before the wastewater enters the biochemical tank, it needs to be evaporated and concentrated first. This process can easily produce toxic and harmful ammonia gas, causing environmental pollution.

[0004] In the biological treatment method, microalgae have the advantages of fast growth and reproduction, high nitrogen fixation efficiency, and simple growth nutritional requirements, and can well absorb nitrogen, phosphorus, carbon and other elements in wastewater as nutrients for their own cell growth and reproduction to complete the purification of wastewater, which is green and environmentally friendly. However, in practical applications, microalgae are mostly used to treat wastewater containing low-concentration nitrogen or wastewater containing single nitrogen form. At the same time, due to the complexity of wastewater composition, the physiological activity of the same algae strain in different sources of wastewater has great difference, and the treatment effect of the same nitrogen in different wastewater is also quite different.

[0005] At present, there is still a lack of a method for efficiently treating ammonia oxamidated wastewater containing high-concentration ammonia nitrogen and nitrate nitrogen by using microalgae. In view of this, the present application is proposed. SUMMARY

[0006] In order to solve the technical problems to be solved by the present application, the present application provides a method for efficiently treating high-nitrogen oxamidated wastewater by microalgae, which can not only efficiently treat high-concentration ammonia nitrogen and nitrate nitrogen oxamidated wastewater by using microalgae, but also realize the efficient utilization of resources of such wastewater by combining with the co-production of high biomass, which has practical guiding significance.

[0007] Specifically, the technical scheme adopted by the present application is as follows:

[0008] The application discloses a method for efficiently treating ammonia-oximation high-nitrogen wastewater by using microalgae.

[0009] The method for efficiently treating ammonia-oximation high-nitrogen wastewater by using microalgae provided by the application can effectively absorb pollutants in the ammonia-oximation wastewater as nutrient substances required by microalgae reproduction through growth of the microalgae in the ammonia-oximation wastewater containing ammonia nitrogen and nitrate nitrogen, thereby achieving efficient removal of ammonia nitrogen and nitrate nitrogen in the ammonia-oximation wastewater, creating high-value microalgae biomass and realizing comprehensive development and utilization of resources; the method can simplify a wastewater treatment process flow of a device, save wastewater treatment operation cost, avoid generation of toxic and harmful ammonia gas in a wastewater concentration treatment process, reduce physical harm to on-site workers and avoid pollution of the environment, thereby achieving multiple values of high efficiency, economy, environmental protection and safety, and is especially suitable for process wastewater with high ammonia nitrogen and nitrate nitrogen.

[0010] Preferably, the culture system further comprises a basic culture medium and a supplementary carbon source.

[0011] Preferably, the basic culture medium is at least one of BG-11 culture medium, Basal culture medium and BBM culture medium without nitrogen source.

[0012] The content of the supplementary carbon source is 10-40 g / L, and the supplementary carbon source is at least one of glucose, glycerol and sucrose.

[0013] Preferably, the microalgae are Chlorella vulgaris or Scenedesmus.

[0014] Preferably, the content of initial ammonia nitrogen in the culture system is 70-90 mg / L, the content of initial nitrate nitrogen is 700-900 mg / L, and the pH value is 7.5-9.

[0015] Preferably, the content of initial ammonia nitrogen in the culture system is 80 mg / L, the content of initial nitrate nitrogen is 800 mg / L, and the pH value is 7.5.

[0016] Preferably, the water quality of the ammonia-oximation wastewater is as follows: the content of total nitrogen is 500-2000 mg / L, the content of nitrate nitrogen is 500-2000 mg / L, the content of ammonia nitrogen is 0-200 mg / L, the content of total phosphorus is 0-200 mg / L, the content of Na + The content of t-butyl alcohol, toluene, cyclohexanone and cyclohexanone oxime is all ≤200 ppm.

[0017] Preferably, the culture conditions comprise the following: the temperature is 20-30 DEG C, the light intensity is 100-300 mu mol / m 2s, and the culture time is 1-12 days.

[0018] Preferably, the microalgae culture ends and further comprises the following steps: centrifugal collection of the algal slurry, freeze-drying, and obtaining the microalgae biomass. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 Growth curve of Chlorella vulgaris in Example 1 and Comparative Example 1;

[0020] Figure 2 Content change curve of nitrate nitrogen in the culture solution of Example 1 and Comparative Example 1;

[0021] Figure 3 Content change curve of ammonia nitrogen in the culture solution of Example 1. DETAILED DESCRIPTION

[0022] In order to better understand the above technical solutions, the exemplary embodiments of the present application will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present application are shown in the drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided so that the present application can be more clearly, thoroughly understood, and the scope of the present application can be completely conveyed to those skilled in the art.

[0023] The embodiment of the present application provides a method for efficiently treating ammonium oxime high-nitrogen wastewater by microalgae, comprising the following steps: inoculating microalgae into a culture system comprising ammonium oxime wastewater containing ammonia nitrogen and nitrate nitrogen for culture.

[0024] In the present application, in order to further effectively remove ammonia nitrogen and nitrate nitrogen, the selected microalgae can be activated and cultured before inoculation, and there is no particular limitation on the activation and culture method.

[0025] In a preferred embodiment of the present application, the culture system further comprises a basic culture medium and a supplemental carbon source.

[0026] In a preferred embodiment of the present application, the basic culture medium is at least one of BG-11 culture medium, Basal culture medium and BBM culture medium without nitrogen source.

[0027] The content of the supplemental carbon source is 10-40 g / L, and the supplemental carbon source is at least one of glucose, glycerol and sucrose.

[0028] In the present application, in order to enable the microalgae to completely utilize the nitrogen source in the ammonium oxime wastewater and achieve efficient denitrification, a nitrogen-free basic culture medium is selected to improve the removal effect of ammonia nitrogen and nitrate nitrogen.

[0029] In a preferred embodiment of the present application, the microalgae is Chlorella vulgaris or Scenedesmus.

[0030] In one preferred embodiment of the present application, the initial content of ammonia nitrogen in the culture system is 70-90 mg / L, the content of nitrate nitrogen is 700-900 mg / L, and the pH value is 7.5-9.

[0031] In the present application, by controlling the concentrations of nitrate nitrogen and ammonia nitrogen in the ammoxilation wastewater, the nitrate nitrogen is ensured to be in the optimal absorption range and the ammonia nitrogen is ensured to be in the optimal absorption tolerance range. When the ammoxilation wastewater contains both ammonia nitrogen and nitrate nitrogen, the algal cell growth will preferentially utilize the ammonia nitrogen to meet the nitrogen requirement for the early development of the cells, which is due to that the ammonia nitrogen can be directly synthesized into amino acids through GS / GAGOT enzyme, while the nitrate nitrogen needs to be first reduced into ammonia nitrogen by the action of reductase. Therefore, in the preferred content range of ammonia nitrogen in the present application, the early growth and development of the algal cells can be effectively promoted, which provides the cell biomass basis for the rapid reproduction and development in the middle logarithmic growth phase, and also provides the conditions for processing more nitrate nitrogen in the later period (the nitrogen requirement for the cell growth in the later period is mainly supplied by the nitrate nitrogen), while the toxicity caused by excessive ammonia nitrogen can also be avoided.

[0032] In one preferred embodiment of the present application, the initial content of ammonia nitrogen in the culture system is 80 mg / L, the content of nitrate nitrogen is 800 mg / L, and the pH value is 7.5. The present application further optimizes the concentrations of nitrate nitrogen and ammonia nitrogen in the ammoxilation wastewater, so that the nitrate nitrogen and ammonia nitrogen are in the optimal absorption values, to achieve the effect of more efficiently utilizing the microalgae to remove the ammonia nitrogen and nitrate nitrogen in the ammoxilation wastewater, and accumulating more mass of biomass.

[0033] In one preferred embodiment of the present application, the water quality of the ammoxilation wastewater is as follows: the content of total nitrogen is 500-2000 mg / L, the content of nitrate nitrogen is 500-2000 mg / L, the content of ammonia nitrogen is 0-200 mg / L, the content of total phosphorus is 0-200 mg / L, the content of Na + is 500-800 mg / L, and the contents of t-butyl alcohol, toluene, cyclohexanone and cyclohexanone oxime are all ≤200 ppm.

[0034] In the present application, when the ammoxilation wastewater contains appropriate amount of organic matters and nutrient elements, it also helps the growth and reproduction of the microalgae to a certain extent.

[0035] In one preferred embodiment of the present application, the culture conditions include: the temperature is 20-30℃, the light intensity is 100-300 μmol / m 2 / s, and the culture time is 1-12 d.

[0036] In one preferred embodiment of the present application, after the microalgae culture is completed, the following steps are further included: centrifugal collection of the algal slurry, freeze-drying, and obtaining the microalgae biomass.

[0037] The present application is described in more detail below through examples, but the present application is not limited to the following examples.

[0038] Measurement method:

[0039] (I) Growth state monitoring: sampling analysis in 24h units, using a spectrophotometer to measure the absorbance at 680nm, and drawing a growth curve.

[0040] (II) Biomass measurement: dry weight method, after the culture is completed, the volume (v) of the culture solution is measured, the algal slurry is centrifugally collected (8000rpm, 5min) into a weighed container, and is placed into a freeze-drying machine for freeze-drying to obtain the dry weight (m) of the algal powder.

[0041] Calculation formula: biomass (B) = m / v, unit g / L.

[0042] (III) Nitrate nitrogen content measurement: spectrophotometry.

[0043] (IV) Ammonia nitrogen content measurement: Nash reagent photometry.

[0044] Example 1

[0045] A method for efficiently treating ammoxidation high-nitrogen wastewater by microalgae, comprising the following steps:

[0046] (1) BG-11 culture medium without nitrogen source is prepared, ammoxidation wastewater containing ammonia nitrogen and nitrate nitrogen is added, and the initial content of ammonia nitrogen in the system is controlled to be 80mg / L, the content of nitrate nitrogen is controlled to be 800mg / L, the pH value is controlled to be 7.5, and 15g / L of glucose is added as a supplementary carbon source to establish a culture system.

[0047] The water quality of the ammoxidation wastewater is as follows: the content of total nitrogen is 500-2000mg / L, the content of nitrate nitrogen is 500-2000mg / L, the content of ammonia nitrogen is 0-200mg / L, the content of total phosphorus is 0-200mg / L, the content of Na + is 500-800mg / L, and the contents of t-butyl alcohol, toluene, cyclohexanone and cyclohexanone oxime are all ≤200ppm.

[0048] (2) The activated Chlorella vulgaris is inoculated into the above culture system, and is cultured under the conditions of a temperature of 25℃ and a light intensity of 180μmol / m 2 / s, and the culture time is 8d.

[0049] (3) Chlorella cultivation was ended, and the algal mud was collected by centrifugation, frozen and dried to obtain the microalgae biomass.

[0050] Example 2

[0051] The difference between this example and Example 1 is that the initial content of ammonia nitrogen in the system is adjusted to 70 mg / L, and the content of nitrate nitrogen is 700 mg / L.

[0052] Example 3

[0053] The difference between this example and Example 1 is that the initial content of ammonia nitrogen in the system is adjusted to 90 mg / L, and the content of nitrate nitrogen is 900 mg / L.

[0054] Comparative Example 1

[0055] The difference between this comparative example and Example 1 is that the ammonia oximation wastewater added does not contain 80 mg / L of ammonia nitrogen.

[0056] Comparative Example 2

[0057] The difference between this comparative example and Example 1 is that the initial content of ammonia nitrogen in the system is adjusted to 100 mg / L.

[0058] Comparative Example 3

[0059] The difference between this comparative example and Example 1 is that the initial content of ammonia nitrogen in the system is adjusted to 40 mg / L.

[0060] Comparing Example 1 and Comparative Example 1, the growth curves of Chlorella under different culture conditions are recorded in Table 1. Figure 1 , which can be used to observe different stages of algal cell growth and development from a dynamic perspective. From Figure 1 It can be seen that under the condition of the presence of nitrate nitrogen, the introduction of ammonia nitrogen has little effect on the growth and development cycle of algal cells. The algal cells in Example 1 and Comparative Example 1 both enter the stationary phase after about 7 days. However, it can shorten the cultivation time of the logarithmic growth phase. In Example 1, the logarithmic growth phase ends on the 5th day, while in Comparative Example 1, it ends on the 7th day. This is due to the fact that the appropriate amount of ammonia nitrogen promotes the growth and development of the cells in the early stage, resulting in an increase in the number of algal cells, which leads to the early depletion of nitrogen nutrients. Combined with the measured biomass data, the algal powder biomass in Example 1 is 3.64 g / L, while in Comparative Example 1 it is 2.76 g / L. Compared with the two, the microalgae biomass in Example 1 is increased by 32%. This shows that in the presence of nitrate nitrogen in the ammonia oximation wastewater, an appropriate amount of ammonia nitrogen is more conducive to the growth and development of algal cells, and helps to accumulate more biomass.

[0061] The contents of nitrate nitrogen and ammonia nitrogen in the culture systems of Example 1 and Comparative Example 1 were determined, and the results are recorded in Table 2. Figure 2 andFigure 3 From Figure 2 and Figure 3 The changes in nitrate nitrogen and ammonia nitrogen content during the growth of algal cells of the algae can be seen. In the first 4 days of the growth and development of the algal cells, the consumption of nitrate nitrogen in Example 1 was much lower than that in Comparative Example 1, and the contents were similar on the 5th day. Similarly, the consumption of ammonia nitrogen content was also mainly concentrated in the first 4 days of the growth and development of the algal cells, and tended to be stable in the middle and later stages. This indicates that the selective absorption of ammonia nitrogen by the algal strain in the early stage of cell growth and development is prior to that of nitrate nitrogen, and the consumption of ammonia nitrogen is mainly in the early stage of cell growth, and the consumption of nitrate nitrogen is mainly in the later stage of cell growth. The above results are consistent with the results of the change process of the growth curve and the difference in biomass accumulation. It is determined that the removal rate of nitrate nitrogen in Example 1 is 90.37%, and the removal rate of ammonia nitrogen is 96.75%; the removal rate of nitrate nitrogen in Comparative Example 1 is 80.64%. This also shows that the appropriate concentrations of nitrate nitrogen and ammonia nitrogen in the ammoxilization wastewater can further improve the removal effect of nitrate nitrogen.

[0062] The culture solutions of Examples 2-3 and Comparative Examples 2-3 were determined, and the results are recorded in Table 1.

[0063] Table 1

[0064] Nitrate nitrogen removal rate (%) Ammonium nitrogen removal rate (%) Biomass (g / L) Example 2 88.75 96.13 3.33 Example 3 87.61 94.85 3.24 Comparative Example 2 65.3 70.42 1.49 Comparative Example 3 87.42 95.21 3.16

[0065] As can be seen from Table 1, compared with Comparative Example 1, the biomass of microalgae in Examples 2 and 3 is increased by 21% and 17%, respectively. Comparing Examples 1-3, it can be seen that the indicators of Example 1 are better than those of Examples 2 and 3, which shows that even if the same ratio of ammonia nitrogen and nitrate nitrogen (both 1:10) is maintained, the specific concentration will also affect the final treatment effect of ammoxilization wastewater. This is mainly because, under the specific water quality and dosage ratio conditions, the selection of 80 mg / L of ammonia nitrogen and 800 mg / L of nitrate nitrogen is the best concentration for the algal strain to treat this type of wastewater, which can make the nitrate nitrogen at the best absorption value and the ammonia nitrogen at the best tolerance value. Comparing Example 1 with Comparative Examples 2-3, it can be seen that the treatment effect of the algal strain on ammoxilization wastewater in Comparative Examples 2-3 has decreased to different degrees, among which the nitrogen removal rate and biomass in Comparative Example 2 decreased significantly, which is due to the addition of ammonia nitrogen content exceeding the maximum tolerance value of the microalgae, resulting in a large number of deaths (the algal liquid is obviously yellow); and in Comparative Example 3, the selected ammonia nitrogen content does not reach the best tolerance value of the algal strain, so the growth and reproduction effect of the algal strain is not as good as that in Example 1, and therefore the treatment effect on the subsequent nitrate nitrogen is slightly reduced.

[0066] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions recorded in the above embodiments can be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for high efficient treatment of ammonia-oximation high nitrogen-containing wastewater by microalgae, comprising the following steps: The microalgae are inoculated into a culture system including ammonium-oxamated wastewater containing ammonia nitrogen and nitrate nitrogen for cultivation; The microalgae are Chlorella or Scenedesmus; The initial content of ammonia nitrogen in the culture system is 70-90 mg / L, the initial content of nitrate nitrogen is 700-900 mg / L, and the pH value is 7.5-9.

2. The method for efficient treatment of ammonia oxime-treated high-nitrogen wastewater using microalgae as described in claim 1, characterized in that, The culture system further includes a basal medium and a carbon source supplement.

3. The method for efficient treatment of ammonia oxime-treated high-nitrogen wastewater using microalgae as described in claim 2, characterized in that, The basal medium is at least one of BG-11 medium, Basal medium and BBM medium without nitrogen source; The content of the carbon source supplement is 10-40 g / L, and the carbon source supplement is at least one of glucose, glycerol and sucrose.

4. The method for efficient treatment of ammonia oxime-treated high-nitrogen wastewater using microalgae as described in claim 1, characterized in that, The initial content of ammonia nitrogen in the culture system is 80 mg / L, the initial content of nitrate nitrogen is 800 mg / L, and the pH value is 7.

5.

5. The method of claim 1, wherein the microalgae efficiently treat the ammonia-oxoformated high nitrogen wastewater. The water quality of the ammoximation wastewater is as follows: the content of total nitrogen is 500-2000 mg / L, the content of nitrate nitrogen is 500-2000 mg / L, the content of ammonia nitrogen is 0-200 mg / L, the content of total phosphorus is 0-200 mg / L, the content of Na + 500-800 mg / L, the content of tert-butyl alcohol, toluene, cyclohexanone and cyclohexanone oxime is all ≤200 ppm.

6. The method of claim 1, wherein the microalgae efficiently treat the ammonia-oxoformated high nitrogen wastewater. The culture conditions include: temperature 20~30℃, light intensity 100~300μmol / m 2 / s, culture time 1~12d.

7. The method of claim 1, wherein the microalgae efficiently treat the ammonia-oxoformated high nitrogen wastewater. The microalgae cultivation further includes the following steps after the cultivation: centrifugal collection of algal sludge, freeze-drying, and obtaining of microalgae biomass.

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