Method for efficiently removing antibiotics through non-contact bacteria-algae combined treatment

Abstract

The invention discloses a method for efficiently removing antibiotics through non-contact bacteria-algae combined treatment, and belongs to the field of biological treatment and water treatment. The separation membrane is arranged in the non-contact bacteria-algae combined treatment system and is used for physically isolating the algae reaction unit from the bacteria reaction unit; chlorella is added into the algae reaction unit; activated sludge is added into the bacterial reaction unit; and the aperture of the separation membrane is smaller than the sizes of cells in the chlorella and the activated sludge. The method for efficiently removing the antibiotics through non-contact bacteria-algae combined treatment is designed, the removal effect on sulfamethoxazole is excellent, the method is obviously superior to an existing common exchange type bacteria-algae synergistic method, and the degradation capacity on the antibiotics is obviously enhanced. According to the non-contact bacteria-algae combined treatment method, the antibiotic removal effect is improved, and meanwhile, the effluent quality almost the same as that of a common exchange type bacteria-algae synergistic reactor is kept.

Description

Technical Field

[0001] This invention relates to the fields of biological treatment and water treatment, and in particular to a method for the efficient removal of antibiotics through non-contact combined treatment of bacteria and algae. Background Technology

[0002] With the widespread use of antibiotics in medicine, livestock and poultry farming, and aquaculture, the pollution of the environment by antibiotics has become an increasingly serious concern. Once antibiotics enter wastewater treatment systems, their stable structure and poor biodegradability make them difficult to remove completely using conventional physical, chemical, or biological treatment methods. This can easily lead to some residual antibiotics entering natural water bodies with the effluent, damaging aquatic ecosystems, and even causing the accumulation and spread of antibiotic resistance genes (ARGs), seriously threatening ecological security and human health.

[0003] To address the problem of antibiotic pollution, various wastewater treatment technologies have been proposed, including advanced oxidation technologies, adsorption methods, membrane separation technologies, and biological treatment methods. Among them, biological treatment methods are widely used in practical engineering due to their advantages such as low cost, low energy consumption, and stable operation. In recent years, the combined treatment method of microalgae and microorganisms has become a research hotspot in the field of antibiotic wastewater biological treatment because it combines the functions of pollutant adsorption, enrichment, transformation, and degradation. Microalgae can fix CO2 under photosynthesis and absorb nutrients such as nitrogen and phosphorus in wastewater, while also having a certain adsorption and biotransformation capacity for some antibiotics; microorganisms can effectively degrade various types of antibiotics, such as penicillins, tetracyclines, and sulfonamides, by relying on their metabolic enzyme systems. Ordinary exchange-type microbial-algae synergistic systems can leverage the synergistic effect of the two by mixing them, thereby improving the removal efficiency of antibiotics in wastewater. However, most existing microbial-algae combined systems are in the form of direct co-cultivation, which has the following problems: (1) there is nutrient competition between microorganisms and algae, affecting the stability of the system; (2) direct contact between microorganisms and algae will cause metabolic interference, reducing the overall degradation capacity. To address the technical challenges of existing bacterial-algae co-culture systems, further improvements are still needed from researchers in this field. Summary of the Invention

[0004] The purpose of this invention is to provide a non-contact combined treatment of bacteria and algae for efficient removal of antibiotics, in order to solve the above-mentioned problems in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] One of the technical solutions of the present invention is to provide a non-contact algae and bacteria co-processing system, wherein the non-contact algae and bacteria co-processing system is provided with a separator membrane for physically isolating the algae reaction unit and the bacterial reaction unit;

[0007] The algae reaction unit contains Chlorella; the bacterial reaction unit contains activated sludge; and the pore size of the separator membrane is smaller than the size of the cells in the Chlorella and activated sludge.

[0008] Preferably, the Chlorella is Chlorella FACHB-9.

[0009] Preferably, the activated sludge is activated sludge from an aerobic tank in wastewater treatment.

[0010] Preferably, the activated sludge is the activated sludge from the aerobic tank of the secondary treatment system of the Longwangzui Wastewater Treatment Plant in Wuhan.

[0011] Preferably, the separator is made of polyvinylidene fluoride with an average pore size of 0.22 μm.

[0012] The second technical solution of the present invention provides an application of the above-mentioned non-contact combined bacterial and algal treatment system in the field of antibiotic pollution treatment.

[0013] The third technical solution of this invention provides a method for efficient removal of antibiotics through non-contact combined treatment of bacteria and algae, comprising the following steps:

[0014] An antibiotic-contaminated aqueous solution is added to the aforementioned non-contact algae and bacteria combined treatment system, and the aqueous solution flows through the algae reaction unit and the bacteria reaction unit to aerate the system during operation.

[0015] Preferably, the concentrations of Chlorella and activated sludge in the antibiotic-contaminated aqueous solution are 1×10⁻⁶. 6 ~3×10 6 2500~4000 mg / L.

[0016] Preferably, the operation mode is intermittent, with aeration for 23 hours and cessation for 1 hour per day, and the dissolved oxygen content during aeration is ≥2 mg / L.

[0017] Because bacteria typically reproduce much faster than algae, excessive bacterial growth in conventional exchange-type bacterial-algae co-treatment systems consumes most of the oxygen and nutrients, inhibiting algae growth. The non-contact bacterial-algae co-treatment method designed in this invention effectively addresses this problem. Furthermore, this non-contact system also solves the problem of reduced algal photosynthesis caused by mixed cultivation.

[0018] Furthermore, the non-contact combined microbial and algae treatment system of this application also has advantages over separate systems. Compared to separate systems that "first treat antibiotic wastewater with microalgae, then treat it with activated sludge," microalgae grow slowly and have limited nitrogen and phosphorus removal when treated alone, and their ability to directly degrade antibiotics is weak. When the treated wastewater is introduced into the bacterial stage, due to the lack of real-time oxygen supply from microalgae, the bacteria can only utilize the limited dissolved oxygen in the wastewater, resulting in incomplete antibiotic degradation.

[0019] Compared to separation systems that first treat antibiotic wastewater with activated sludge and then with microalgae, although bacteria can degrade some antibiotics in the first stage, the subsequent microalgae treatment has limited mineralization capacity, and small-molecule antibiotics usually persist. The membrane separation system of this invention, through real-time metabolic relay, significantly improves the mineralization degree of antibiotics, demonstrating the core role of this non-contact circulating exchange system in enhancing degradation.

[0020] The beneficial technical effects of the present invention are as follows:

[0021] This invention presents a non-contact combined bacterial and algal treatment method for the efficient removal of antibiotics. It exhibits excellent removal efficiency for sulfamethoxazole, significantly outperforming existing conventional exchange-type bacterial and algal synergistic methods and significantly enhancing the degradation capacity of antibiotics.

[0022] This non-contact combined bacterial and algal treatment method improves antibiotic removal while maintaining almost the same effluent quality as ordinary exchange-type bacterial and algal co-reactors.

[0023] Furthermore, the processing system of the present invention can also recover the algae after processing, thereby realizing the recycling of algal biomass and reducing pollution and waste.

[0024] The core of this invention lies in physically isolating microorganisms and microalgae through membrane separation. While allowing the cyclical exchange of nutrients, oxygen, CO2, and dissolved organic matter, direct contact between bacteria and algae is blocked. This design avoids direct competition and toxic interference from biomass, and enhances pollutant degradation and resource recovery through cyclical exchange. It provides a new approach for constructing efficient, controllable, and sustainable antibiotic wastewater treatment systems, and has significant application value. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a comparison chart of the sulfamethoxazole removal rates of the non-contact bacteria-algae combined treatment method in Example 1 and the conventional exchange-type bacteria-algae synergistic method in Comparative Example 1.

[0027] Figure 2 This is a comparison chart showing the ammonia nitrogen removal effects of the non-contact bacteria-algae combined treatment method in Example 1 and the conventional exchange-type bacteria-algae synergistic method in Comparative Example 1.

[0028] Figure 3 This is a comparison chart showing the nitrite removal effects of the non-contact bacteria-algae combined treatment method in Example 1 and the conventional exchange-type bacteria-algae synergistic method in Comparative Example 1.

[0029] Figure 4 This is a comparison chart showing the nitrate removal effects of the non-contact bacteria-algae combined treatment method in Example 1 and the conventional exchange-type bacteria-algae synergistic method in Comparative Example 1.

[0030] Figure 5 This study compares the sludge flocculation rate and Chlorella recovery rate of the non-contact bacteria-algae combined treatment method in Example 1 and the conventional exchange-type bacteria-algae synergistic method in Comparative Example 1. Detailed Implementation

[0031] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0032] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0033] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. It should be noted that any aspects of this invention not described in detail are conventional practices in the art and are not the focus of this invention.

[0034] The terms “comprising,” “including,” “having,” “containing,” etc., used in this invention are all open-ended terms, meaning that they include but are not limited to.

[0035] Unless otherwise specified, "room temperature" in this invention refers to 10-30°C.

[0036] All raw materials used in the following embodiments and comparative examples of the present invention are commercially available products.

[0037] Example 1

[0038] A non-contact combined bacterial and algal treatment method for highly efficient removal of antibiotics includes the following steps:

[0039] (1) Constructing a reactor

[0040] Activated sludge was obtained from the aerobic tank of the secondary treatment system at the Longwangzui Wastewater Treatment Plant in Wuhan and acclimated. Before the formal experiment, a 45-day stabilization culture was conducted (the culture method involved placing the activated sludge in an intermittent aeration device containing simulated wastewater, with an operating cycle of 24 hours, including 23 hours of continuous aeration; dissolved oxygen content ≥2 mg / L during aeration; and 500 mL of influent and effluent per cycle; the simulated wastewater formula is described below) to adapt it to laboratory conditions, ultimately yielding acclimated activated sludge. The acclimated activated sludge developed a bacterial community dominated by heterotrophic organic pollutant degrading bacteria and nitrogen conversion-related functional bacteria. The dominant functional microbial community consists of Variovorax, Hydrogenophaga, Delftia, and Flavobacterium, accompanied by a small amount of auxiliary metabolic bacteria commonly found in activated sludge systems (such as Pseudomonaceae and Acinetobacter), collectively constituting a functional microbial system capable of removing organic pollutants and antibiotics. The total viable count in the acclimated activated sludge remained stable at 1 × 10⁻⁶. 7 -1×10 8 CFU / mL, and the aforementioned dominant functional bacteria account for 60%-85% of the total bacteria count.

[0041] A non-contact algae and bacteria co-processing system was established, comprising separate algae and bacterial reaction units (volume ratio 1:1), separated by a Millipore 0.22μm polyvinylidene fluoride (PVDF) membrane. The system employs a sequencing batch reactor (SBR) design, with reactors made of plexiglass. Each reactor has a total volume of 2 L and a working volume of 1 L. The reactor was filled with 1 L of simulated wastewater, the composition of which was: CH3COONa 0.512 g / L, NH4Cl 0.19 g / L, KH2PO4 0.044 g / L, NaHCO3 1.5 g / L, CaCl2 0.1 g / L, MgSO4∙7H2O 0.1 g / L, EDTA 0.35 mg / L, ZnSO4∙7H2O 0.2 mg / L, CuSO4∙5H2O 0.1 mg / L, MnSO4∙7H2O 0.2 mg / L, Pb(NO3)2 6H2O 0.09 mg / L, H3BO3 0.1 mg / L, and Na2MoO4 0.1 mg / L.

[0042] The purchased Chlorella FACHB-9 and the acclimated activated sludge were added to the algae reaction unit and the bacterial reaction unit of the non-contact algae-bacteria co-treatment system, respectively.

[0043] (2) Operating the reactor

[0044] The system was operated continuously under aerobic, room temperature conditions, with the concentrations of Chlorella FACHB-9 and acclimated activated sludge in the system controlled at 2×10⁻⁶. 6 The concentrations were 3000 mg / L and 3000 mg / L. During the simulation experiment, the operating cycle was set to 24 h, with continuous aeration for 23 h (dissolved oxygen content ≥2 mg / L during aeration). Each cycle produced 500 mL of influent and 500 mL of effluent. Water quality indicators were monitored daily, and an equal volume of simulated wastewater was replaced. After 20 days of stable system operation, sulfamethoxazole (SMX) was added to the influent at a concentration of 5 mg / L, and the same operating conditions were maintained.

[0045] (3) Observe the reactor's ability to remove pollutants.

[0046] From the date of SMX addition, effluent samples were collected daily to determine conventional water quality indicators such as ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen. The residual concentration of SMX was also detected using high-performance liquid chromatography (HPLC). The removal performance of the reactor for antibiotics and the system stability were continuously assessed during long-term operation by replacing the simulated wastewater containing 5 mg / L SMX daily.

[0047] The detection methods are as follows: the concentrations of nitrate nitrogen, nitrite nitrogen, and ammonia nitrogen are determined by ultraviolet spectrophotometry for the determination of nitrate nitrogen in water (HJ / T 346-2007), spectrophotometry for the determination of nitrite nitrogen in water (GB 7493-87), and Nessler's reagent spectrophotometry for the determination of ammonia nitrogen in water (HJ 535-2009).

[0048] The concentration of the target antibiotic sulfamethoxazole (SMX) was analyzed by high performance liquid chromatography (HPLC) under the following chromatographic conditions: the mobile phase was an aqueous solution containing 0.1% (v / v) formic acid and acetonitrile at a volume ratio of 70:30; the flow rate was set to 1.0 mL / min; the column temperature was maintained at 35℃; the autosampler injection volume was 20 μL; and a UV detector was used with a detection wavelength of 268 nm.

[0049] (4) Biomass recycling and analysis

[0050] After the experiment, Chlorella was isolated from the algae reaction unit of the non-contact system, and its recovery rate was determined. At the same time, the flocculation rate of the sludge in the system was also determined.

[0051] Comparative Example 1

[0052] A common exchange-type bacterial-algae synergistic method:

[0053] The only difference from Example 1 is that the non-contact algae-bacteria co-treatment system is replaced with a conventional exchange-type algae-bacteria co-treatment system. Specifically, the conventional exchange-type algae-bacteria co-treatment system omits the polyvinylidene fluoride membrane from the non-contact algae-bacteria co-treatment system, no longer distinguishes between algae reaction units and bacterial reaction units, and instead simultaneously adds the same concentration of Chlorella FACHB-9 and acclimated activated sludge.

[0054] Effect verification

[0055] To verify the superiority of the treatment method designed in this invention, the treatment effects and system performance of Example 1 (non-contact bacterial-algae combined treatment method) and Comparative Example 1 (ordinary exchange-type bacterial-algae synergistic method) were compared and analyzed. The results are as follows:

[0056] Figure 1 This is a comparison chart of the sulfamethoxazole removal rates of the non-contact bacteria-algae combined treatment method in Example 1 and the conventional exchange-type bacteria-algae synergistic method in Comparative Example 1.

[0057] Figure 2 This is a comparison chart showing the ammonia nitrogen removal effects of the non-contact bacteria-algae combined treatment method in Example 1 and the conventional exchange-type bacteria-algae synergistic method in Comparative Example 1.

[0058] Figure 3This is a comparison chart showing the nitrite removal effects of the non-contact bacteria-algae combined treatment method in Example 1 and the conventional exchange-type bacteria-algae synergistic method in Comparative Example 1.

[0059] Figure 4 This is a comparison chart showing the nitrate removal effects of the non-contact bacteria-algae combined treatment method in Example 1 and the conventional exchange-type bacteria-algae synergistic method in Comparative Example 1.

[0060] Figure 5 This study compares the sludge flocculation rate and Chlorella recovery rate of the non-contact bacteria-algae combined treatment method in Example 1 and the conventional exchange-type bacteria-algae synergistic method in Comparative Example 1.

[0061] like Figure 1 As shown, the non-contact bacteria-algae co-treatment system of Example 1 achieved a removal rate of 43.8% for SMX, which is significantly higher than the 33.1% of the ordinary exchange-type bacteria-algae co-treatment system of Comparative Example 1. The removal effect is improved by more than 10%, which proves that the non-contact structure of the present invention has obvious advantages in enhancing the antibiotic degradation effect.

[0062] Figure 2 , Figure 3 and Figure 4 The removal effects of Example 1 and Comparative Example 1 on ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen were compared. The test results showed that the removal effects of both on conventional nitrogen pollutants were similar, indicating that the present invention significantly improves the removal rate of antibiotics without sacrificing the system's ability to treat traditional pollutants, demonstrating the system's comprehensive functionality.

[0063] like Figure 5 As shown, the sludge flocculation rate of the non-contact system in Example 1 reached 40%, which is higher than that of Comparative Example 1, indicating that the wastewater treatment performance of the present invention is superior. Furthermore, Example 1 successfully recovered microalgae, with a Chlorella recovery rate of 16.3%; while the ordinary exchange system in Comparative Example 1 could not recover Chlorella. Therefore, the treatment method defined in this invention can reduce secondary pollution and conserve resources to a greater extent.

[0064] The higher sludge flocculation rate in Example 1 is due to the fact that, compared to direct mixing and cultivation, the non-contact system of this invention effectively avoids direct contact and competition between bacterial and algal cells through physical isolation. This facilitates the formation of a stable skeletal structure in the bacterial-dominated bioflocs, thus preventing the structural loosening caused by algal cells embedding into the flocs. Simultaneously, the algal units provide a relatively stable and favorable metabolic microenvironment for the bacterial units through transmembrane diffusion of metabolites (such as oxygen and soluble organic matter). This not only promotes the enrichment of specific bacterial populations with extracellular polymeric substance (EPS) production capabilities but also increases the protein content in the produced EPS, thereby significantly enhancing the compactness and overall structural stability of the sludge flocs.

[0065] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A non-contact combined bacteria and algae treatment system, characterized in that, The non-contact algae and bacteria combined treatment system is equipped with a separator membrane to physically isolate the algae reaction unit and the bacterial reaction unit. The algae reaction unit contains Chlorella; the bacterial reaction unit contains activated sludge; and the pore size of the separator membrane is smaller than the size of the cells in the Chlorella and activated sludge.

2. The non-contact combined bacteria and algae treatment system according to claim 1, characterized in that, The Chlorella species in question is Chlorella FACHB-9.

3. The non-contact combined bacteria and algae treatment system according to claim 1, characterized in that, The activated sludge is the activated sludge from the aerobic tank of wastewater treatment.

4. The non-contact combined bacteria and algae treatment system according to claim 1, characterized in that, The separator is made of polyvinylidene fluoride and has an average pore size of 0.22 μm.

5. The application of the non-contact combined bacterial and algal treatment system according to any one of claims 1-4 in the field of antibiotic pollution treatment.

6. A method for efficient removal of antibiotics through non-contact combined treatment of bacteria and algae, characterized in that, Includes the following steps: An antibiotic-contaminated aqueous solution is added to the non-contact algae and bacteria combined treatment system according to any one of claims 1-4, and the aqueous solution flows through the algae reaction unit and the bacteria reaction unit to aerate the system during operation.

7. The method according to claim 6, characterized in that, The concentrations of Chlorella and activated sludge in the antibiotic-contaminated aqueous solution were 1×10⁻⁶. 6 ~3×10 6 2500~4000 mg / L.

8. The method according to claim 6, characterized in that, The system adopts an intermittent operation mode, aerating for 23 hours and stopping for 1 hour daily, with dissolved oxygen content ≥2 mg / L during aeration.

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