A method for treating aquaculture wastewater using chlorella

Abstract

The application discloses a method for treating aquaculture wastewater by using chlorella, which comprises the following steps: adding chlorella and zeolite powder into the aquaculture wastewater to remove COD. By adding the zeolite powder into the aquaculture wastewater, the chlorella is fixed by the zeolite powder, the chlorella grows on the surface of the zeolite powder, and the activity range of paramecium is limited by the zeolite powder, so that the influence of the paramecium on the normal growth process of the chlorella is weakened, the chlorella can always maintain high COD removal capacity, the removal of the subsequent chlorella is solved, and the difficulty of the advanced treatment of the aquaculture wastewater is reduced. The method has the advantages of simple operation, green environmental protection, low cost and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, and in particular to a method for treating aquaculture wastewater by utilizing Chlorella vulgaris. Background Art

[0002] With the rapid development of the aquaculture industry, the amount of aquaculture wastewater is increasing. The large amount of animal feed required during the aquaculture process, coupled with the large amount of feces produced by animals, contributes to high concentrations of COD in aquaculture wastewater. If aquaculture wastewater is discharged directly into surface and groundwater environments without proper treatment, the excessive organic matter it contains can increase microbial growth, increase oxygen consumption, and lead to hypoxia in the water environment, posing a significant threat to the environment.

[0003] Treatment methods for aquaculture wastewater are divided into physical, chemical and biological methods. Physical methods (e.g. filtration, adsorption) are mainly used to remove pollutants such as suspended solids, ammonia nitrogen, and phosphorus in aquaculture wastewater. This method requires a large amount of chemicals and has poor treatment effects. Chemical methods (e.g. flocculation, advanced oxidation) can fully remove nitrogen, phosphorus and various organic matter, but the cost of adding flocculants and oxidants is high, the economic investment is large, and secondary pollution will occur. Biological methods (e.g. activated sludge method, biofilm method) use microorganisms to remove organic matter, with low economic investment, complete treatment, no secondary pollution, and good application prospects.

[0004] Chlorella can simultaneously carry out photosynthesis and respiration under light conditions. It consumes organic matter through reproduction and growth, achieving a high COD removal rate while also using the algae cells obtained as a biomass energy source. However, because the process of treating wastewater with Chlorella is open, Chlorella will be contaminated by Paramecium during long-term cultivation. This will not only affect the proliferation of Chlorella, but also reduce the COD removal effect of Chlorella. Currently, the main way to avoid the influence of Paramecium is to replace the Chlorella stock solution, but this operation will undoubtedly increase economic investment, and new pollution phenomena will also appear in the future, which cannot fundamentally solve the problem of Paramecium contamination. Summary of the Invention

[0005] The object of the present invention is to provide a method for treating aquaculture wastewater by using Chlorella which can eliminate the influence of Paramecium.

[0006] The technical solution adopted by the present invention is:

[0007] A method for treating aquaculture wastewater using chlorella comprises the following steps: adding chlorella and zeolite powder into the aquaculture wastewater to remove COD.

[0008] Preferably, the amount of Chlorella added to the aquaculture wastewater is 4.00×10 6 cell / mL~6.00×106 cell / mL.

[0009] Preferably, the Chlorella is added in the form of Chlorella culture solution.

[0010] Preferably, the Chlorella culture solution is prepared by inoculating Chlorella into sterilized BG-11 medium and then performing light-dark cycle culture, thereby obtaining the Chlorella culture solution.

[0011] Preferably, the inoculation concentration of the Chlorella is 1.00*10 6 cell / mL~5.00*10 6 cell / mL.

[0012] Preferably, the specific operation of the light-dark cycle culture is as follows: first, culturing for 8h~16h under the condition that the temperature is 24~26℃ and the light intensity is 1000Lux~3000Lux, then culturing for 8h~16h after turning off the light, and taking one cycle, and performing the cycle culture for 5d~10d.

[0013] Preferably, the adding amount of the zeolite powder in the aquaculture wastewater is 0.1g / L~30g / L.

[0014] Preferably, the particle size of the zeolite powder is <10um.

[0015] Preferably, the COD content of the aquaculture wastewater is 1500mg / L~2500mg / L.

[0016] Preferably, the COD removal is performed under the condition that the temperature is 24~26℃.

[0017] Preferably, the time of the COD removal is 5d~10d.

[0018] The present application has the advantages that: by adding the zeolite powder in the aquaculture wastewater, the present application uses the zeolite powder to adsorb and fix the Chlorella, so that the Chlorella grows on the surface of the zeolite powder, and the zeolite powder limits the activity range of the Paramecium, thereby weakening the influence of the Paramecium on the normal growth process of the Chlorella, so that the Chlorella can always maintain high COD removal capacity, and the subsequent removal of the Chlorella is solved, and the difficulty of the advanced treatment of the aquaculture wastewater is reduced, and the method has the advantages of simple operation, green environmental protection, low cost and the like. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 Figure is the test result graph of the influence of the zeolite powder on the normal growth process of the Chlorella.

[0020] Figure 2 Figure is the test result graph of the influence of the Paramecium on the normal growth process of the Chlorella.

[0021] Figure 3 This is the test result of the effect of Paramecium on the COD removal effect of Chlorella.

[0022] Figure 4 This is a graph showing the test results of the effect of zeolite powder on the proliferation ability of Chlorella in the process of using Chlorella to treat aquaculture wastewater in Example 1.

[0023] Figure 5 This is a graph showing the test results of COD removal effect during the treatment of aquaculture wastewater using zeolite adsorption-desorption-Chlorella suspended growth in Example 2.

[0024] Figure 6 This is a graph showing the test results of COD removal effect in the process of treating aquaculture wastewater using zeolite adsorption-standing-Chlorella attachment growth in Example 3.

[0025] Figure 7 This is a summary chart of COD removal rates during wastewater treatment by Chlorella under different conditions. DETAILED DESCRIPTION

[0026] The present invention will be further explained and illustrated below with reference to specific embodiments.

[0027] Test on the effect of zeolite powder on the normal growth process of Chlorella:

[0028] Chlorella sp. was inoculated into sterilized BG-11 medium at a concentration of 5.00×10 6 cell / mL, and set the COD of the solution to 2000 mg / L, and compare the changes in the growth process of Chlorella with the COD removal ability, and add zeolite powder (particle size <10 μm), the dosage of zeolite powder is 20 g / L (experimental group), and then perform light-dark cycle culture. The specific operation of light-dark cycle culture is: first culture at a temperature of 25 ° C and a light intensity of 2000 Lux for 12 hours, and then culture for 12 hours after turning off the light source. This is one cycle, and the total cycle culture is 7 days (7 cycles), and a control group is set. Except for not adding zeolite powder, the rest is exactly the same as the experimental group. The test results of the effect of zeolite powder on the normal growth process of Chlorella are as follows Figure 1 (“Adsorption” represents the experimental group, and “suspension” represents the control group).

[0029] Depend on Figure 1It can be seen that after 7 days of circulation culture, the COD removal concentration of the experimental group was 742.67 mg / L, and the COD removal concentration of the control group was 909.45 mg / L. The COD removal concentration of the experimental group was slightly lower. The reason is that the zeolite powder can adsorb and fix Chlorella, allowing Chlorella to grow on the surface of the zeolite powder. In the attached state, Chlorella cannot move freely and has relatively fewer opportunities to contact organic matter in the solution, resulting in a slight decrease in the COD removal effect. Overall, the zeolite powder has little effect on the treatment capacity of Chlorella.

[0030] Test on the effect of Paramecium on the normal growth process of Chlorella:

[0031] Chlorella sp. was inoculated into sterilized BG-11 medium (experimental group) at a concentration of 5.00×10 6 The cells were cultured at 1.00 × 10 cells / mL and then cultured under light-dark cycle. The specific operation of light-dark cycle culture was as follows: cultured at 25 °C and 2000 Lux for 12 h, then cultured for 12 h after turning off the light source. This was considered one cycle. The culture was cultured for 7 days (7 cycles). A control group was set up. In addition, an additional 1.00 × 10 4 Except for the paramecium of 100 cells / mL, the rest were exactly the same as the experimental group. The concentration of Chlorella was tested every 1 day. The test results are as follows: Figure 2 (“Normal growth” represents the experimental group, and “Paramecium effect” represents the control group).

[0032] Depend on Figure 2 It can be seen that after 7 days of cycle culture, the concentration of Chlorella in the experimental group was 3.61×10 7 cell / mL, while the concentration of Chlorella in the control group was only 1.29×10 7 cell / mL. The reason is that Paramecium has a great influence on the normal growth process of Chlorella. The predation of Chlorella cells by Paramecium will lead to a great reduction in the concentration of Chlorella.

[0033] Test on the effect of Paramecium on COD removal of Chlorella:

[0034] 1) Inoculate Chlorella sp. into sterilized BG-11 medium at a concentration of 5.00×10 6 cell / mL, and then cultured under light-dark cycle. The specific operation of light-dark cycle culture is: first culture at a temperature of 25°C and a light intensity of 2000 Lux for 12 hours, and then culture for 12 hours after turning off the light source. This is one cycle, and the cycle culture is carried out for a total of 7 days (7 cycles) to obtain the Chlorella culture solution;

[0035] 2) The culture medium of Chlorella was added to the aquaculture wastewater (COD content was 2000 mg / L) (experimental group). The dosage of Chlorella in the aquaculture wastewater was 5.00×10 6 cell / mL, and then COD removal was carried out for 7 days at a temperature of 25℃. A control group was set up, in addition to the BG-11 medium inoculated with an additional concentration of 1.00×10 4 Except for the paramecium of 100 cells / mL, the rest were exactly the same as the experimental group. The COD removal rate and COD removal concentration were tested every 1 day. The test results are as follows: Figure 3 (“Normal growth” represents the experimental group, and “Paramecium effect” represents the control group).

[0036] Depend on Figure 3 It can be seen that after 7 days of COD removal, the COD removal concentration of the experimental group was 909.45 mg / L and the COD removal rate was 45.47%, while the COD removal concentration of the control group was only 115.00 mg / L and the COD removal rate was only 5.75%, indicating that Paramecium has a great influence on the COD removal effect of Chlorella.

[0037] Example 1:

[0038] A method for treating aquaculture wastewater using Chlorella vulgaris, comprising the following steps:

[0039] 1) Inoculate Chlorella sp. into sterilized BG-11 medium at a concentration of 5.00×10 6 cell / mL, and then cultured under light-dark cycle. The specific operation of light-dark cycle culture is: first culture at a temperature of 25°C and a light intensity of 2000 Lux for 12 hours, and then culture for 12 hours after turning off the light source. This is one cycle, and the cycle culture is carried out for a total of 7 days (7 cycles) to obtain the Chlorella culture solution;

[0040] 2) Chlorella culture solution and zeolite powder (particle size <10 μm) were added to aquaculture wastewater (COD content was 2000 mg / L). The dosage of Chlorella in aquaculture wastewater was 5.00×10 6 cell / mL, the dosage of zeolite powder in the aquaculture wastewater was 0.1g / L, 0.2g / L and 0.3g / L respectively (3 parallel tests, and a control group without zeolite powder was set up), and then cultured at a temperature of 25℃ for 7 days, and the cell concentration of Chlorella vulgaris was tested every 1 day. The test results are as follows Figure 4 shown.

[0041] Depend on Figure 4It can be seen that in the presence of zeolite, Chlorella can always maintain a high proliferation ability, but the concentration of Chlorella in the experimental group decreased compared with the control group, possibly due to problems such as the activity of Chlorella.

[0042] Example 2:

[0043] A method for treating aquaculture wastewater using Chlorella vulgaris, comprising the following steps:

[0044] 1) Inoculate Chlorella sp. into sterilized BG-11 medium at a concentration of 5.00×10 6 cell / mL, and then cultured under light-dark cycle. The specific operation of light-dark cycle culture is: first culture at a temperature of 25°C and a light intensity of 2000 Lux for 12 hours, and then culture for 12 hours after turning off the light source. This is one cycle, and the cycle culture is carried out for a total of 7 days (7 cycles) to obtain the Chlorella culture solution;

[0045] 2) Add the Chlorella culture solution and zeolite powder (particle size <10 μm) to a solution containing 1×10 4 cell / mL Paramecium aquaculture wastewater (COD content is 2000 mg / L), the addition amount of Chlorella in the aquaculture wastewater is 5.00×10 6 cell / mL, the dosage of zeolite powder in aquaculture wastewater was 0.1g / L, 0.2g / L and 0.3g / L (3 groups of parallel tests), and then COD removal was carried out for 7 days at a temperature of 25℃. The chlorella was first adsorbed and precipitated by shaking, and then the chlorella was desorbed and suspended by shaking. The COD removal effect of chlorella on 7 days was measured. The test results are as follows Figure 5 shown.

[0046] Depend on Figure 5 It can be seen that the highest COD removal rate in this embodiment is 35.13%.

[0047] Example 3:

[0048] A method for treating aquaculture wastewater using Chlorella vulgaris, comprising the following steps:

[0049] 1) Inoculate Chlorella sp. into sterilized BG-11 medium at a concentration of 5.00×10 6 cell / mL, and then cultured under light-dark cycle. The specific operation of light-dark cycle culture is: first culture at a temperature of 25°C and a light intensity of 2000 Lux for 12 hours, and then culture for 12 hours after turning off the light source. This is one cycle, and the cycle culture is carried out for a total of 7 days (7 cycles) to obtain the Chlorella culture solution;

[0050] 2) Chlorella culture solution and zeolite powder (particle size <10 μm) were added to aquaculture wastewater (COD content was 2000 mg / L). The dosage of Chlorella in aquaculture wastewater was 5.00×10 6 cell / mL, the dosage of zeolite powder in aquaculture wastewater was 0.1g / L, 0.2g / L and 0.3g / L (3 groups of parallel tests), and then COD removal was carried out for 7 days at a temperature of 25℃. The chlorella was first adsorbed and precipitated by shaking, and then the COD was removed by static cultivation for 7 days. The COD removal effect of chlorella on 7 days was measured. The test results are as follows Figure 6 As shown (will Figure 2 、 Figure 5 and Figure 6 In summary, the COD removal rate of Chlorella in the process of treating wastewater under different conditions is summarized as follows Figure 7 shown).

[0051] Depend on Figure 6 It can be seen that the highest COD removal rate in this example is 36.75%. This indicates that the addition of zeolite powder to adsorb and fix Chlorella and Paramecium restricts the movement range of Paramecium cells to a certain area, reducing their impact on Chlorella. Ultimately, the COD removal ability of Chlorella is significantly improved.

[0052] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for treating aquaculture wastewater using Chlorella, characterized in that: The aquaculture wastewater contains Paramecium, and the method comprises the following steps: adding chlorella and zeolite powder to the aquaculture wastewater to remove COD; the zeolite powder is used to adsorb and fix the chlorella, so that the chlorella grows on the surface of the zeolite powder, and the zeolite powder is used to limit the activity range of the Paramecium; when treating the aquaculture wastewater, the chlorella is first adsorbed and precipitated by shaking, and then the chlorella is desorbed and suspended by shaking; the amount of chlorella added to the aquaculture wastewater is 4.00×10 6 cell / mL~6.00×10 6 cell / mL; the chlorella is added in the form of a chlorella culture solution; the chlorella culture solution is prepared by the following method: inoculating chlorella into a sterilized BG-11 culture medium, and then subjecting the culture to a light-dark cycle to obtain a chlorella culture solution; the inoculation concentration of the chlorella is 1.00×10 6 cell / mL~5.00×10 6 cell / mL; the specific operation of the light-dark cycle culture is: first culture for 8h to 16h under the conditions of a temperature of 24°C to 26°C and a light intensity of 1000Lux to 3000Lux, and then culture for 8h to 16h after turning off the light source, which is considered as one cycle, and the total cycle culture is 5d to 10d; the addition amount of the zeolite powder to the aquaculture wastewater is 0.1g / L to 0.3g / L; the particle size of the zeolite powder is less than 10μm.

2. The method according to claim 1, wherein: The COD removal is carried out at a temperature of 24°C to 26°C.

3. The method according to claim 1 or 2, characterized in that: The COD removal time is 5d to 10d.

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