Method for removing acephate and sulfamethoxazole in mariculture wastewater

Abstract

The application discloses a method for removing acetamiprid and sulfamethoxazole in mariculture wastewater, which comprises four steps of culturing of sulfur autotrophic denitrifying bacteria, domestication of salt-tolerant sulfur autotrophic denitrifying bacteria, obtaining of sludge containing salt-tolerant and drug-resistant sulfur autotrophic denitrifying bacteria and treatment of mariculture wastewater. The flue gas from a recycling factory is used as an inorganic carbon source for the salt-tolerant and drug-resistant sulfur autotrophic denitrifying sludge in the treatment of mariculture wastewater, which helps to enhance the removal capacity of the sulfur autotrophic denitrifying sludge for nitrate nitrogen, acetamiprid and sulfamethoxazole, and meanwhile realizes the resource utilization of the flue gas. The synergistic effect of the flue gas and the salt-tolerant and drug-resistant sulfur autotrophic denitrifying sludge effectively realizes carbon emission reduction, and significantly reduces the content of nitrate nitrogen, acetamiprid and sulfamethoxazole in the wastewater. When the CO2 concentration in the flue gas is 20%, the removal rate of nitrate nitrogen can reach 96.22%, the removal rate of acetamiprid can reach 81.84%, and the removal rate of sulfamethoxazole can reach 85.42%.

Description

TECHNICAL FIELD

[0001] The application relates to a method for removing acetamiprid and sulfamethoxazole in mariculture wastewater and belongs to the technical field of environmental engineering. BACKGROUND

[0002] In the past four decades, with the continuous improvement of the quality of people's life, the aquaculture industry in China has developed rapidly, among which the mariculture industry has become an indispensable part of the aquaculture industry. However, the development of economy is often accompanied by the destruction of the ecological environment. In the process of mariculture, in order to ensure the more healthy growth of the cultured objects and achieve the maximum benefit, a certain amount of drugs will be usually put into the mariculture water. The mariculture fish is prone to suffer from helminthiasis and bacterial enteritis, and acetamiprid and sulfamethoxazole will be usually added to the mariculture water for prevention and treatment. The large use of acetamiprid poses a great threat to food safety, because acetamiprid will generate the intermediate product of highly toxic methamidophos during storage and use, increasing the difficulty of investigation and supervision effect of the banned methamidophos. Sulfamethoxazole belongs to sulfonamides (SAs), which is one of the largest antibiotics in production, sales and use in China, and has the characteristics of wide antibacterial spectrum, high stability and strong hydrophilicity, and can interfere with and inhibit the growth and reproduction of bacteria. However, antibiotics cannot be completely decomposed and absorbed by the human body and animals, and exist in the form of parent compounds or metabolites in excrement. The detection rate of antibiotics in feces and urine is 75% to 90%. It is common in most countries to apply livestock manure to farmland, and the residual antibiotics will also enter the farmland soil through the application of manure organic fertilizer or irrigation of fecal and urine wastewater, endangering the microbial activity and ecological function, and further affecting the process of microorganisms participating in the ecological system. At the same time, from the molecular genetic level, acetamiprid and sulfamethoxazole can change the community structure of microorganisms in the environment, causing pathogenic bacteria to develop drug resistance. The residual antibiotics in the environment will be accumulated and amplified among all levels of organisms, and enter the human body through the food chain, posing a potential threat to the ecological environment and human health. In summary, it is extremely important to remove acetamiprid and sulfamethoxazole in mariculture wastewater.

[0003] Since the mariculture wastewater also contains a large amount of nitrate nitrogen, it is expected to find a wastewater treatment technology which can not only efficiently remove nitrogen, but also effectively remove acetamiprid and sulfamethoxazole in mariculture wastewater. In terms of nitrogen removal technology, autotrophic denitrification without adding organic carbon source is the first choice, among which sulfur autotrophic denitrification has attracted widespread attention because the raw materials of the process are widely available, no additional organic matter needs to be added, the sludge yield is low, and the operation cost is low.

[0004] The acceleration of industrialization process also leads to significant increase of flue gas emission, the volume fraction of CO2 in flue gas is several hundred times higher than that of CO2 in air, the increasing emission of CO2 leads to gradually aggravating greenhouse effect, which causes melting of icebergs and rising of sea level, and will cause flooding of coastal delta and frequent drought and flood disasters in tropics and temperate zones. Therefore, the combination of flue gas and wastewater treatment process has become the research focus of current wastewater treatment technology, which realizes resource utilization of CO2 and wastewater treatment. SUMMARY

[0005] In order to achieve the above-mentioned purpose, the present application aims to provide a method for removing acetamiprid and sulfamethoxazole in mariculture wastewater, which uses sludge containing salt-tolerant and drug-resistant sulfur autotrophic denitrifying bacteria group to purify mariculture wastewater, and pumps in flue gas in the process, which realizes resource utilization of CO2 and efficient removal of nitrate nitrogen, acetamiprid and sulfamethoxazole.

[0006] One of the purposes of the present application is to provide a method for removing acetamiprid and sulfamethoxazole in mariculture wastewater, which comprises the following steps:

[0007] (1) inoculating anaerobic sludge in a sulfur autotrophic denitrification reactor, and passing a prepared nitrate solution into the reactor to culture sulfur autotrophic denitrifying bacteria group;

[0008] (2) after the culture of sulfur autotrophic denitrifying bacteria group is completed, passing sodium chloride solution into the reactor of step (1) to domesticate salt-tolerant sulfur autotrophic denitrifying bacteria group;

[0009] (3) after the domestication of salt-tolerant sulfur autotrophic denitrifying bacteria group is completed, passing mariculture wastewater into the reactor of step (2) to further domesticate salt-tolerant sulfur autotrophic denitrifying bacteria group, so as to obtain sludge containing salt-tolerant and drug-resistant sulfur autotrophic denitrifying bacteria group;

[0010] (4) placing the sludge containing salt-tolerant and drug-resistant sulfur autotrophic denitrifying bacteria group obtained in step (3) into a new reactor, passing mariculture wastewater into the reactor, and pumping flue gas into the reactor, so as to obtain mariculture wastewater meeting seawater quality standards.

[0011] The flue gas referred to in the present application refers to flue gas generated in a factory, preferably waste gas discharged by a thermal power plant.

[0012] In an embodiment of the present application, the components of flue gas include 10-20% of CO2, 100mg / m 3 of SO2, 100mg / m 3 of NO x , and a small amount of fluoride and chloride.

[0013] In one embodiment of the present application, in step (1), the concentration of the nitrate solution is 20-25 mg / L.

[0014] In one embodiment of the present application, in step (1), the residence time of the nitrate solution is 12 h, and the culture of the sulfur autotrophic denitrifying bacteria is completed when the content of nitrate nitrogen in the effluent is less than 1 mg / L.

[0015] In one embodiment of the present application, the culture step of the sulfur autotrophic denitrifying bacteria comprises: taking 500 mL of anaerobic sludge mixed liquor, stirring uniformly, and then adding to the sulfur autotrophic denitrification reactor, and passing in artificial water prepared by potassium nitrate with a nitrate nitrogen content of 20 mg / L, and setting the hydraulic retention time to 12 h, and culturing the sulfur autotrophic denitrifying bacteria, and measuring the content of nitrate nitrogen in the effluent at a fixed time every day, and if the content of nitrate nitrogen in the effluent is less than 1 mg / L for three consecutive days, then the culture of the sulfur autotrophic denitrifying bacteria is completed.

[0016] In one embodiment of the present application, in step (2), when the sodium chloride solution is passed in, the initial concentration of the sodium chloride is 2.5-5 g / L, and then the concentration of the sodium chloride is gradually increased until the concentration of the sodium chloride passed in reaches 35-40 g / L, and the culture of the salt-tolerant sulfur autotrophic denitrifying bacteria is completed when the content of nitrate nitrogen in the effluent is less than 1 mg / L.

[0017] In one embodiment of the present application, in step (2), the residence time of the sodium chloride aqueous solution with different concentrations is 3-10 days.

[0018] In one embodiment of the present application, in step (3), the initial concentration of nitrate nitrogen in the seawater aquaculture wastewater passed in is 2.5-3 mg / L, the concentration of acephate is 0.8-1.2 mg / L, and the concentration of sulfamethoxazole is 2.2-2.5 mg / L, and then the concentration of the seawater aquaculture wastewater is gradually increased until the concentration of nitrate nitrogen in the seawater aquaculture wastewater passed in is 25-30 mg / L, the concentration of acephate is 8-12 mg / L, and the concentration of sulfamethoxazole is 22-25 mg / L.

[0019] In one embodiment of the present application, in step (3), the residence time of the seawater aquaculture wastewater with different concentrations of nitrate nitrogen is 3-8 days.

[0020] In one embodiment of the present application, in step (4), the concentration of nitrate nitrogen in the seawater aquaculture wastewater passed in is 25-30 mg / L, the concentration of acephate is 8-12 mg / L, and the concentration of sulfamethoxazole is 22-25 mg / L.

[0021] In an embodiment of the present application, in step (4), the volume fraction of CO2 in the pumped flue gas is 10-50%.

[0022] The second object of the present application is to provide a use of the sludge containing the salt-tolerant and drug-resistant sulfur autotrophic denitrifying bacteria group obtained by the above method in wastewater treatment.

[0023] In an embodiment of the present application, the use includes treating domestic sewage, freshwater product aquaculture wastewater, seawater product aquaculture wastewater, pharmaceutical wastewater, etc. with the sludge containing the salt-tolerant and drug-resistant sulfur autotrophic denitrifying bacteria group.

[0024] In an embodiment of the present application, the use includes removing nitrate nitrogen, total nitrogen, antibiotic drugs, etc. in wastewater with the sludge containing the salt-tolerant and drug-resistant sulfur autotrophic denitrifying bacteria group.

[0025] The beneficial effects of the present application are:

[0026] (1) The present application recovers the flue gas from the factory and uses it as an inorganic carbon source for the salt-tolerant sulfur autotrophic denitrifying sludge to treat seawater aquaculture wastewater, which helps to enhance the removal capacity of the sulfur autotrophic denitrifying sludge for nitrate nitrogen, acephate and sulfamethoxazole, and at the same time realizes the resource utilization of the flue gas.

[0027] (2) The synergistic effect of the flue gas and the salt-tolerant sulfur autotrophic denitrifying sludge effectively realizes carbon emission reduction, and significantly reduces the content of nitrate nitrogen, acephate and sulfamethoxazole in the wastewater. When the CO2 concentration in the flue gas is 20%, the removal rate of nitrate nitrogen can reach 96.22%, the removal rate of acephate can reach 81.84%, and the removal rate of sulfamethoxazole can reach 85.42%, which meets the seawater quality standard.

[0028] (3) The use of different concentrations of sodium chloride solution to domesticate the sulfur autotrophic denitrifying bacteria group helps the sulfur autotrophic denitrifying bacteria group to adapt to different concentrations of salt-containing wastewater more quickly, so that the bacteria group develops salt tolerance, in order to improve the ability of the salt-tolerant sulfur autotrophic denitrifying bacteria group to treat salt-containing wastewater.

[0029] (4) The use of different concentrations of seawater aquaculture wastewater to domesticate the sulfur autotrophic denitrifying bacteria group helps to improve the drug resistance of the sulfur autotrophic denitrifying bacteria group, so that the sulfur autotrophic denitrifying bacteria group can better play a role in treating different concentrations of seawater aquaculture wastewater, in order to improve the removal capacity of the bacteria group for nitrate nitrogen and drugs in seawater aquaculture wastewater. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 The figure shows the change of the content of nitrate nitrogen in the reactor during the domestication process of the salt-tolerant sulfur autotrophic denitrifying bacteria group.

[0031] Figure 2The content changes of nitrate nitrogen, acetochlor and sulfamethoxazole in the reactor when the sulfur autotrophic denitrification bacteria population is domesticated using mariculture wastewater.

[0032] Figure 3 The content changes of nitrate nitrogen in mariculture wastewater when flue gas with different CO2 concentrations is pumped in.

[0033] Figure 4 The content changes of acetochlor in mariculture wastewater when flue gas with different CO2 concentrations is pumped in.

[0034] Figure 5 The content changes of sulfamethoxazole in mariculture wastewater when flue gas with different CO2 concentrations is pumped in. DETAILED DESCRIPTION

[0035] The preferred embodiments of the present application are described below, and it should be understood that the embodiments are for better explaining the present application and are not used to limit the present application.

[0036] Example 1: Removal of acetochlor and sulfamethoxazole in mariculture wastewater

[0037] ① Cultivation and domestication of salt-tolerant sulfur autotrophic denitrification bacteria population

[0038] 500 mL of anoxic tank sludge mixture was taken, stirred uniformly, and then added to the sulfur autotrophic denitrification reactor, and artificial water with a nitrate nitrogen content of 20 mg / L prepared by potassium nitrate was introduced, and the hydraulic retention time was set to 12 h to cultivate the sulfur autotrophic denitrification bacteria population. After about 30 days of inoculation operation, the second stage was entered, and sodium chloride aqueous solution was added to the reactor, and the concentration of sodium chloride in the initial sodium chloride aqueous solution was 2.5 g / L. Since salinity can affect the activity of the bacteria population, even if the effluent nitrate nitrogen content is stable below 1 mg / L for three consecutive days, the operation time of each stage needs to be extended to ensure that the microorganisms adapt to the salt-containing environment, thereby domesticating the salt-tolerant bacteria population. During the process of domesticating the bacteria population with sodium chloride aqueous solution, the residence time of the aqueous solution was 10 days, and after 10 days, the concentration of the introduced sodium chloride aqueous solution was increased to continue domestication. When the concentration of the influent sodium chloride was gradually adjusted to 35 g / L, and the effluent nitrate nitrogen was still stable below 1 mg / L, it was indicated that the domestication of the salt-tolerant bacteria population was completed. The content changes of the effluent nitrate nitrogen in the reactor during the domestication process of the salt-tolerant sulfur autotrophic denitrification bacteria population are shown in Table 1. Figure 1 .

[0039] ② Domestication of salt-tolerant sulfur autotrophic denitrification bacteria population in mariculture wastewater

[0040] The influent of the reactor was changed from the original artificial prepared potassium nitrate aqueous solution to the seawater fish farming wastewater. The concentration of nitrate nitrogen in the seawater fish farming wastewater was 25 mg / L, the concentration of acephate was 10 mg / L, and the concentration of sulfamethoxazole was 25 mg / L. Since the actual seawater fish farming wastewater was more complex and contained a certain amount of drugs, in order to ensure that the activity of the microorganisms was not affected, the wastewater was diluted 10 times, and then pumped into the reactor, that is, the concentration of nitrate nitrogen in the seawater fish farming wastewater was 2.5 mg / L, the concentration of acephate was 1 mg / L, and the concentration of sulfamethoxazole was 2.5 mg / L. In order to gradually adapt the microorganisms to the environment of high NO3 - -N, high salinity and high drug content, prevent the impact of high load on the activity of the microorganisms, and when the removal efficiency of the pollutants in the low concentration seawater farming wastewater was stable, the dilution multiple of the wastewater was gradually reduced, that is, the concentration of the seawater fish farming wastewater was increased, until the seawater farming wastewater with the concentration of nitrate nitrogen of 25 mg / L, the concentration of acephate of 10 mg / L, and the concentration of sulfamethoxazole of 25 mg / L was pumped in. The concentration changes of nitrate nitrogen, acephate and sulfamethoxazole in the seawater farming wastewater during the process of acclimatizing the salt-tolerant sulfur autotrophic denitrifying bacteria group to the seawater farming wastewater are shown in Table 2. Figure 2 .

[0041] From Figure 2 As can be seen from the results shown, after being acclimated to the seawater farming wastewater with different concentrations, the sludge containing the salt-tolerant sulfur autotrophic denitrifying bacteria group can achieve the removal rates of nitrate nitrogen of 90.17%, the removal rates of acephate of 62.12%, and the removal rates of sulfamethoxazole of 67.49% under the condition of pumping in the original wastewater without dilution.

[0042] ③Removal of acephate and sulfamethoxazole in seawater farming wastewater by flue gas

[0043] On the basis of step ②, the mud-water mixture in the reactor was taken and added to 5 different reactors, and an equal volume of seawater fish farming wastewater was pumped into the reactors. The concentration of nitrate nitrogen in the seawater fish farming wastewater was 25 mg / L, the concentration of acephate was 10 mg / L, and the concentration of sulfamethoxazole was 25 mg / L. Then, flue gas with different CO2 concentrations (v / v) was pumped into the reactors. The CO2 concentrations of the flue gas pumped into the reactors 1-5 were 10%, 20%, 30%, 40% and 50%, respectively. The experiment was carried out in a closed space for 3 days, and the effluent was sampled every 12 h. The concentration changes of nitrate nitrogen, acephate and sulfamethoxazole in the effluent are shown in Table 4. Figures 3-5 .

[0044] The results show that the treatment effect of the low volume CO2 group is better, and when the volume of CO2 is 20%, the removal effect of pollutants is obviously enhanced, the removal rate of nitrate nitrogen can reach 96.22%, the removal rate of acephate is 81.84%, and the removal rate of sulfamethoxazole is 85.42%, which shows that the flue gas rich in CO2 can strengthen the salt-tolerant sulfur autotrophic denitrification process to remove nitrate nitrogen, acephate and sulfamethoxazole in wastewater.

[0045] Example 2: Determination of the hydraulic retention time of the salt-tolerant sulfur autotrophic denitrification process

[0046] After the acclimation of the salt-tolerant bacteria group, the hydraulic retention time of the reactor is adjusted to explore the limit treatment capacity and the most suitable operating condition of the reactor. Table 1 is the comparison and selection of the hydraulic retention time of the salt-tolerant sulfur autotrophic denitrification process. When the hydraulic retention time is between 1-12h, the effluent nitrate nitrogen is less than 1mg / L, which can reach the second class water quality standard in the sea water quality standard (GB 3097-1997). When the hydraulic retention time is shortened to 0.5h, the treatment effect is obviously decreased.

[0047] Table 1 Comparison and selection of the hydraulic retention time of the salt-tolerant sulfur autotrophic denitrification process

[0048]

[0049] Although the present application has been disclosed with reference to the preferred embodiments as above, it is not intended to limit the present application, and any person skilled in the art can make various modifications and modifications without departing from the spirit and scope of the present application, therefore the protection scope of the present application should be defined by the claims.

Claims

1. A method for removing acephate and sulfamethoxazole from marine aquaculture wastewater, characterized in that, Includes the following steps: (1) Inoculate anaerobic sludge into a sulfur autotrophic denitrification reactor, introduce a prepared nitrate solution into the reactor, and cultivate sulfur autotrophic denitrifying bacteria. When the nitrate nitrogen content in the effluent of the reactor is less than 1 mg / L, the cultivation of sulfur autotrophic denitrifying bacteria is completed. The concentration of the nitrate solution is 20-25 mg / L. (2) After the sulfur autotrophic denitrifying bacteria community has been cultured, sodium chloride solution is introduced into the reactor of step (1) to acclimate the salt-tolerant sulfur autotrophic denitrifying bacteria community. When introducing sodium chloride solution, the initial concentration of sodium chloride is 2.5-5 g / L, and then the concentration of sodium chloride is gradually increased until the concentration of sodium chloride reaches 35-40 g / L. When the nitrate nitrogen content in the effluent of the reactor is less than 1 mg / L, the sulfur autotrophic denitrifying bacteria community culture is completed. (3) After the salt- and sulfur-tolerant autotrophic denitrifying bacteria have been domesticated, seawater aquaculture wastewater is introduced into the reactor in step (2) to further domesticate the salt- and sulfur-tolerant autotrophic denitrifying bacteria, so as to obtain sludge containing salt- and sulfur-tolerant autotrophic denitrifying bacteria. The initial concentration of nitrate nitrogen in the introduced seawater aquaculture wastewater is 2.5-3 mg / L, the concentration of acephate is 0.8-1.2 mg / L, and the concentration of sulfamethoxazole is 2.2-2.5 mg / L. The concentration of seawater aquaculture wastewater is gradually increased until the concentration of nitrate nitrogen in the introduced aquaculture wastewater is 25-30 mg / L, the concentration of acephate is 8-12 mg / L, and the concentration of sulfamethoxazole is 22-25 mg / L. (4) The sludge containing salt-tolerant, drug-resistant, sulfur-tolerant, autotrophic denitrifying bacteria obtained in step (3) is placed into a new reactor, and seawater aquaculture wastewater is introduced into the reactor. Flue gas with a volume fraction of CO2 of 20% is pumped into the reactor to obtain seawater aquaculture wastewater that meets the seawater quality standards. The concentration of nitrate nitrogen in the seawater aquaculture wastewater is 25-30 mg / L, the concentration of acephate is 8-12 mg / L, and the concentration of sulfamethoxazole is 22-25 mg / L.

2. The removal method according to claim 1, characterized in that, In step (1), the residence time of the nitrate solution is 12 hours.

3. The removal method according to claim 1, characterized in that, The residence time for sodium chloride solutions of different concentrations is 3 to 10 days.

4. The removal method according to claim 1, characterized in that, In step (3), the retention time of marine aquaculture wastewater with different nitrate nitrogen concentrations is 3 to 8 days.

5. The use of sludge containing salt-tolerant, drug-resistant, sulfur-tolerant, autotrophic denitrifying bacteria obtained by the method according to claim 1 in wastewater treatment.

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