Method for treating antibiotic wastewater by using high-concentration ammonia-nitrogen wastewater and application thereof

Abstract

The application discloses a method for treating antibiotic wastewater by using high-concentration ammonia-nitrogen wastewater and application thereof, and belongs to the technical field of purification treatment. The method is characterized in that: microalgae cells cultured to the logarithmic phase are inoculated into sterilized high-concentration ammonia-nitrogen wastewater for culture, and then the microalgae cells are used for treating antibiotic wastewater. The method provided by the application has remarkable economic benefits, and the microalgae are widely distributed in nature, so that no additional carbon source is needed, and the cost is low. Moreover, more extracellular proteins are secreted by using high-concentration ammonia-nitrogen, and the microalgae remove the antibiotics while achieving the purpose of treating ammonia-nitrogen.

Description

Technical Field

[0001] This invention belongs to the field of purification and treatment technology, specifically relating to a method for treating antibiotic wastewater using high-concentration ammonia nitrogen wastewater and its application. Background Technology

[0002] Antibiotics, as highly effective drugs for treating microbial infections, are widely used in the pharmaceutical, livestock, and aquaculture industries. Most antibiotics cannot be absorbed and utilized by humans and animals, and are released into the environment as metabolites such as feces and urine, negatively impacting the ecological environment. Currently, due to the extensive use or abuse of antibiotics, they are frequently detected in various aquatic environments, such as surface water, groundwater, urban sewage, and industrial wastewater. Furthermore, residual antibiotics in the environment can induce and spread antibiotic resistance, thus posing a potential threat to human health.

[0003] Nitrogen (N), a typical water pollutant, exists in both organic and inorganic forms. Among all forms of nitrogen in wastewater, ammonia nitrogen is considered the most important pollutant. Ammonia nitrogen mainly exists in the form of non-ionic ammonia nitrogen (NH3) and ionized ammonium ions (NH4+). + Ammonia nitrogen exists in two forms and is found in high concentrations in domestic wastewater, industrial waste, and livestock waste. Large-scale discharge of ammonia nitrogen wastewater can lead to eutrophication of water bodies and disrupt their ecological balance. Given the wide distribution and difficulty in achieving discharge standards for ammonia nitrogen wastewater, the economical and low-consumption treatment of high-ammonia nitrogen wastewater is a primary task for wastewater resource utilization, harmless treatment, and the protection of water environment safety.

[0004] Existing methods for treating ammonia nitrogen wastewater mainly include physicochemical methods and biological methods (such as aerobic and anaerobic activated sludge processes). Biological methods have received widespread attention due to their advantages such as low cost, minimal secondary pollution, and environmental friendliness. However, biological methods still face some problems in practical applications of treating high-ammonia nitrogen wastewater, mainly in the following two aspects: the wastewater is complex and contains a certain concentration of antibiotics. Because the functional bacteria used in traditional biological methods (activated sludge processes) for antibiotic degradation are mostly prokaryotes, and antibiotics have a strong bactericidal effect on prokaryotes, the bacterial community exhibits low activity, unstable structure, and poor antibiotic degradation efficiency during the antibiotic degradation process, resulting in antibiotics flowing into downstream water bodies.

[0005] Algae are a highly diverse group of photosynthetic microorganisms that can rapidly grow using light, carbon, and nitrogen sources, and have shown great potential in antibiotic removal. Notably, biosorption plays a crucial role in the removal of antibiotics by algae. Current methods for antibiotic removal primarily focus on algae-bacteria composite technologies. While these technologies can address the stability issues of pure algae systems to some extent, they are not conducive to controlling the spread of antibiotic resistance genes, nor are they beneficial for the secretion of extracellular proteins in algae or the dispersion of microalgal cells. Consequently, their ability to bind antibiotics cannot be further improved. Summary of the Invention

[0006] The purpose of this invention is to solve the technical problems of existing methods for treating antibiotic wastewater using algae-bacteria composite antibiotics, which cannot inhibit the spread of antibiotic resistance genes and are not conducive to the secretion of extracellular proteins of algae and the dispersion of microalgal cells. The invention provides a method for treating antibiotic wastewater using high-concentration ammonia nitrogen wastewater and its application.

[0007] One objective of this invention is to provide a method for treating antibiotic wastewater using high-concentration ammonia nitrogen wastewater, the method comprising the following steps:

[0008] Microalgal cells cultured to the logarithmic growth phase were inoculated into sterilized high-concentration ammonia nitrogen wastewater and then used to treat antibiotic wastewater.

[0009] To further define, microalgae include Microcystis aeruginosa, Chlorella vulgaris, Chlorella pyrenoidosa, Spirulina platensis, Chlamydomonas reinhardtii, and Chlamydomonas sp. Tai-3.

[0010] Further specifying the preparation process of microalgal cell precipitate: first, microalgae are added to BG-11 culture medium and pre-cultured in a photobioreactor until the logarithmic phase to obtain microalgal solution, which is then centrifuged and washed to obtain microalgal cell precipitate.

[0011] Furthermore, the microalgal biomass in the microalgal solution is specified to be 0.85–1.0 g / L.

[0012] Further, it is specified that it is sterilized by high temperature.

[0013] Further restrictions apply to high-concentration ammonia nitrogen wastewater NH4 + -N concentration ≥200mg / L.

[0014] Further specify the inoculum size for microalgae cell precipitation as 50-100 mg / L.

[0015] Further, the inoculation was carried out in sterilized high-concentration ammonia nitrogen wastewater for 2.5-3.5 days. The pH was adjusted to neutral 36 hours after the start of the culture process, and then the pH of the water was adjusted to neutral every 12 hours thereafter.

[0016] Further, the pH of the antibiotic wastewater was adjusted to neutral 36 hours after treatment began, and then the pH of the water was adjusted to neutral every 12 hours thereafter.

[0017] The second objective of this invention is to provide an application of the above-mentioned method in the simultaneous treatment of high-concentration ammonia nitrogen wastewater and antibiotic wastewater.

[0018] Further defining high-concentration ammonia nitrogen wastewater includes anaerobic nitrification sludge concentrate, livestock wastewater, rare earth element tailings water, landfill leachate, and biogas slurry.

[0019] Further specifying, the antibiotics include at least one of sulfamethoxazole, sulfadiazine, sulfadiazine, chlortetracycline, oxytetracycline, florfenicol, ofloxacin, norfloxacin, ciprofloxacin, and enrofloxacin.

[0020] The advantages of this invention are:

[0021] (1) This invention utilizes high-concentration ammonia nitrogen wastewater to promote the secretion of proteins in microalgal extracellular polymers (EPS), thereby increasing the binding strength and binding capacity for antibiotics. When the EPS content is 3%-5%, the microalgal cells will always be in a dispersed state, and high-concentration ammonia nitrogen can stimulate the secretion of microalgal extracellular proteins, thereby promoting the removal of antibiotics.

[0022] (2) This invention provides a method for treating antibiotic wastewater using high-concentration ammonia nitrogen wastewater. This waste-to-waste approach offers significant economic benefits. Furthermore, microalgae are widely distributed in nature, requiring no external carbon source, resulting in low cost. High-concentration ammonia nitrogen allows for the secretion of more extracellular proteins; the average extracellular protein yield in high-ammonia nitrogen wastewater is 1.15-4.15 times that in low-ammonia nitrogen wastewater. Microalgae achieve the goal of treating ammonia nitrogen while simultaneously removing antibiotics, thus achieving multiple benefits. Attached Figure Description

[0023] Figure 1 The diagram shows the effect of algal biomass on the water samples treated in step (3) of Example 1 and Comparative Example 1.

[0024] Figure 2 The graph shows the effect of extracellular protein secretion in the water samples treated in step (3) of Example 1 and Comparative Example 1.

[0025] Figure 3This is a diagram showing the removal effect of NH4+-N in the water sample treated in step (3) of Example 1;

[0026] Figure 4 This is a diagram showing the TP removal effect of the water sample treated in step (3) of Example 1;

[0027] Figure 5 This is a graph showing the effect of extracellular protein secretion in the water sample treated in step (4) of Example 1;

[0028] Figure 6 The NH4 in the water sample treated in step (4) of Example 1 + -N removal effect diagram;

[0029] Figure 7 This is a diagram showing the effect of TP removal in the water sample treated in step (4) of Example 1.

[0030] Figure 8 The image shows the effect of ciprofloxacin and tetracycline removal in the water sample treated in step (4) of Example 1. Detailed Implementation

[0031] One method for treating antibiotic wastewater using high-concentration ammonia nitrogen wastewater according to this embodiment is carried out according to the following steps:

[0032] (1) Microalgae were added to BG-11 medium and pre-cultured in a photobioreactor until the logarithmic growth phase. The pre-culture parameters were: culture temperature 29–32℃, culture rotation speed 200–300 rpm, and culture light intensity 150–300 μmol / m². 2 / s, aeration culture, the aeration gas consists of CO2 and air, where the mass fraction of CO2 is 1-3%, the aeration rate is 1-2L / min, to obtain a microalgal solution with a microalgal biomass of 0.85-1.0g / L. After centrifugation at 6000rpm for 3min, the supernatant is discarded, and the algal cell precipitate obtained after centrifugation is washed with distilled water. After centrifugation at 6000rpm for 3min, the supernatant is discarded to obtain the microalgal cell precipitate.

[0033] The microalgae mentioned in step (1) include Microcystis aeruginosa, Chlorella vulgaris, Chlorella pyrenoidosa, Spirulina platensis, Chlamydomonas reinhardtii, and Chlamydomonas sp. Tai-3.

[0034] (2) Microalgal cell pellets cultured to the logarithmic growth phase were inoculated into high-concentration ammonia nitrogen wastewater after high-temperature sterilization and cultured for 2.5-3.5 days. The inoculation amount of microalgal cell pellets was 50-100 mg / L. The culture parameters were: culture temperature 29-32℃, culture speed 200-300 rpm, and light intensity 150-300 μmol / m². 2 The aeration process involves aeration culture, with the aeration gas consisting of CO2 and air, where the CO2 mass fraction is 1-3%, and the aeration rate is 1-2 L / min. After the initial 36 hours of cultivation, the pH is adjusted to neutral, and thereafter adjusted to neutral every 12 hours. This solution is then used to treat antibiotic wastewater. During the treatment of antibiotic wastewater, the temperature is controlled at 29-32℃, the rotation speed at 200-300 rpm, and the light intensity at 150-300 μmol / m². 2 / s, the aeration gas consists of CO2 and air, with the mass fraction of CO2 being 1-3%, the aeration rate being 1-2 L / min, the treatment lasts for more than 6 days, and the pH is adjusted to neutral 36 hours after the start of the treatment of antibiotic wastewater, and then the pH of the water body is adjusted to neutral every 12 hours thereafter.

[0035] In step (2), the high-concentration ammonia nitrogen wastewater NH4 + -N concentration ≥200mg / L, specifically including anaerobic nitrification sludge concentrate, livestock wastewater, rare earth element tailings water, landfill leachate, and biogas slurry. Antibiotics include at least one of sulfamethoxazole, sulfadiazine, sulfadimidine, chlortetracycline, oxytetracycline, florfenicol, ofloxacin, norfloxacin, ciprofloxacin, and enrofloxacin.

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0037] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials, reagents, methods, and instruments used are all conventional materials, reagents, methods, and instruments in the art, and can be obtained commercially by those skilled in the art.

[0038] The terms “comprising,” “including,” “having,” “containing,” or any other variations thereof, as used in the following embodiments, are intended to cover a non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such a composition, step, method, article, or apparatus.

[0039] In the following embodiments, "an embodiment" or "embodiment" refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that excludes other embodiments.

[0040] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1 to 5” is disclosed, the described range should be interpreted as including ranges “1 to 4”, “1 to 3”, “1 to 2”, “1 to 2 and 4 to 5”, “1 to 3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range. In this specification and claims, range definitions may be combined and / or interchanged, unless otherwise stated, these ranges include all subranges contained therein.

[0041] The indefinite articles “a” and “an” preceding an element or component of this invention do not impose any limitation on the quantity (i.e., number of times) of the element or component. Therefore, “an” or “a” should be interpreted as including one or at least one, and the singular form of an element or component also includes the plural form, unless the quantity clearly refers only to the singular form.

[0042] In the following examples, EPS extraction was performed using a heating method. The specific procedure was as follows: 20 ml of algal solution was taken, centrifuged at 25°C and 6000 rpm for 3 min to remove the supernatant, washed with distilled water and centrifuged again to obtain microalgal precipitate, 20 ml of 0.85% NaCl solution was added, and the mixture was placed in a water bath at 60°C for 30 min, centrifuged at 25°C and 10000 rpm for 20 min, and filtered through a 0.45 μm filter to obtain the EPS solution.

[0043] Organic matter determination in the following examples: Protein determination was performed using the Lowry method.

[0044] The antibiotic detection conditions in the following examples were: Agilent HPLC system, mobile phase of 20% acetonitrile and 80% formic acid, C18 column, and flow rate of 1 mL / min.

[0045] Example 1: This example describes a method for treating antibiotic wastewater using high-concentration ammonia nitrogen wastewater, which is carried out according to the following steps:

[0046] (1) Preparation of microalgal cell pellet: Chlorella pyrenoidosa was added to BG-11 medium and pre-cultured in a photobioreactor to the logarithmic growth phase. The pre-culture parameters were: culture temperature 30℃, culture rotation speed 300 rpm, and culture light intensity 200 μmol / m². 2 / s, aeration culture, the aeration gas consists of CO2 and air, where the mass fraction of CO2 is 2%, the aeration rate is 1.5L / min, to obtain a microalgal solution with a Chlorella biomass of 0.9g / L. After centrifugation at 6000rpm for 3min, the supernatant is discarded, and the algal cell precipitate obtained after centrifugation is washed with distilled water. After centrifugation at 6000rpm for 3min, the supernatant is discarded to obtain the microalgal cell precipitate.

[0047] (2) Prepare artificially simulated high-concentration ammonia nitrogen wastewater: pH: 7.25±0.05, COD: 650mg / L, NO 3- -N: 45mg / L, NH4 + -N: 417mg / L, TP: 15mg / L, and sterilized at high temperature.

[0048] (3) The microalgal cell precipitate obtained in step (1) was inoculated into the high-concentration ammonia nitrogen wastewater obtained in step (2) at a concentration of 80 mg / L and cultured for 3 days. The culture parameters were: culture temperature 30℃, culture rotation speed 300 rpm, and culture light intensity 200 μmol / m². 2 / s, aeration culture, the aeration gas consists of CO2 and air, with the mass fraction of CO2 being 2%, the aeration rate is 1.5L / min, the pH is adjusted to neutral after 36h of culture, and then the pH of the water is adjusted to neutral every 12h thereafter.

[0049] (4) The product from step (3) was passed into antibiotic wastewater (ciprofloxacin concentration 10 mg / L, tetracycline concentration 10 mg / L, and a blank control was set up). During the treatment, the temperature was controlled at 30℃, the rotation speed at 300 rpm, and the light intensity at 200 μmol / m². 2 / s, the aeration gas consists of CO2 and air, with CO2 having a mass fraction of 2%, the aeration rate is 1.5L / min, the treatment lasts for 6 days, the pH is adjusted to neutral 36 hours after the start of the treatment process, and then the pH of the water is adjusted to neutral every 12 hours thereafter.

[0050] Comparative Example 1: The difference between this comparative example and Example 1 is that: in step (2), low-concentration ammonia nitrogen wastewater was prepared, NH4 + -N: 1 mg / L, other parameters are the same as those for high-concentration ammonia nitrogen wastewater. In step (3), the microalgae cell precipitate obtained in step (1) is inoculated into low-concentration ammonia nitrogen wastewater at a concentration of 80 mg / L.

[0051] (i) Every 24 hours, water samples treated in step (3) of Example 1 and Comparative Example 1 were taken to determine the algal biomass and extracellular protein concentration, and to analyze the extracellular protein secretion in high-concentration ammonia nitrogen wastewater:

[0052] Algal biomass was determined by ultraviolet spectrophotometry at a wavelength of 680 nm. Results are as follows: Figure 1 As shown from Figure 1 It can be seen that the microalgal biomass is significantly greater under high concentration ammonia nitrogen conditions than under low concentration ammonia nitrogen conditions.

[0053] Protein levels were determined using the Lowry method, with bovine serum albumin (BSA) as the standard. Results are as follows: Figure 2 As shown, from Figure 2 It can be seen that the extracellular proteins produced under high concentration ammonia nitrogen conditions are significantly more than those produced under low concentration ammonia nitrogen conditions. On average, the extracellular proteins produced under high concentration ammonia nitrogen conditions are 3.84 times more than those produced under low concentration ammonia nitrogen conditions.

[0054] (ii) Every 24 hours, water samples treated in step (3) of Example 1 were taken to determine the removal of ammonia nitrogen and total phosphorus:

[0055] Nessler's reagent method for the treatment of NH4 in water + -N is used for detection, and the results are as follows: Figure 3 As shown, NH4 can be seen + -N removal effect is obvious.

[0056] The molybdenum-antimony spectrophotometric method was used to detect TP in water, and the results are as follows: Figure 4 As shown, TP was almost completely removed on the second day.

[0057] (III) Every 24 hours, water samples treated in step (4) of Example 1 were taken to determine the concentrations of extracellular protein, ammonia nitrogen, total phosphorus, and antibiotics, and to analyze the extracellular protein secretion and pollutant removal in high-concentration ammonia nitrogen wastewater:

[0058] Using bovine serum albumin (BSA) as a standard, the results are as follows: Figure 5 As shown, it can be seen that the secretion of extracellular proteins was not significantly affected in the antibiotic-containing system.

[0059] Nessler's reagent method for the treatment of NH4 in water + -N is used for detection, and the results are as follows: Figure 6 As shown, it can be seen that after 5 days of culture, the antibiotic-containing system has a significant effect on NH4+. + -N removal effect is obvious.

[0060] The molybdenum-antimony spectrophotometric method was used to detect TP in water, and the results are as follows: Figure 7 As shown, TP was almost completely removed on the second day.

[0061] Ciprofloxacin and tetracycline in water were detected using HPLC, and the results are as follows: Figure 8 As shown, the effect of culturing for 5 days on ciprofloxacin and tetracycline hydrochloride is very obvious.

[0062] The above description is merely a preferred embodiment of the present invention. These specific embodiments are different implementations based on the overall concept of the present invention, and the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for treating antibiotic wastewater using high-concentration ammonia nitrogen wastewater, characterized in that, The method described: Microalgal cells cultured to the logarithmic growth phase were inoculated into sterilized high-concentration ammonia nitrogen wastewater to promote the secretion of extracellular proteins in microalgae, and then used to treat antibiotic wastewater. Preparation process of microalgal cell precipitate: Microalgae were first added to a BG-11 culture medium and pre-cultured to the logarithmic growth phase in a photobioreactor to obtain a microalgal solution. This solution was then centrifuged and washed to obtain the microalgal cell precipitate. The microalgal biomass in the solution was 0.85~1.0 g / L. High-concentration ammonia nitrogen wastewater (NH4) + -N concentration ≥200mg / L; inoculate into sterilized high-concentration ammonia nitrogen wastewater and culture for 2.5-3.5 days. Adjust the pH to neutral 36 hours after the start of the culture process, and then adjust the pH of the water to neutral every 12 hours thereafter; the inoculation amount of microalgae cells is 50-100mg / L; adjust the pH to neutral 36 hours after the start of the treatment of antibiotic wastewater, and then adjust the pH of the water to neutral every 12 hours thereafter.

2. The method according to claim 1, characterized in that, Microalgae include Microcystis aeruginosa, Chlorella vulgaris, Chlorella pyrenoidosa, Sporulina platensis, Chlamydomonasreinhardtii, Chlamydomonas sp.Tai-3.

3. The application of the method according to claim 1 or 2 in the simultaneous treatment of high-concentration ammonia nitrogen wastewater and antibiotic wastewater.

4. The application according to claim 3, characterized in that, High-concentration ammonia nitrogen wastewater includes anaerobic nitrification sludge concentrate, livestock wastewater, rare earth element tailings water, landfill leachate, and biogas slurry. Antibiotics include at least one of sulfamethoxazole, sulfadiazine, sulfadiazine, chlortetracycline, oxytetracycline, florfenicol, ofloxacin, norfloxacin, ciprofloxacin, and enrofloxacin.

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