Process for treating antibiotic wastewater by combined microorganism-mbr membrane

Abstract

The present application relates to sewage biological treatment technical field, specifically discloses a kind of process for treating antibiotic wastewater of composite microorganism-MBR membrane joint processing.The present application provides a kind of process for treating antibiotic wastewater of composite microorganism-MBR membrane joint processing, by COD gradient rise and removal rate control, directional acclimation and toxicity screening are carried out to activated sludge, and microbial community that is impacted by sulfamethoxazole is built;Further introduce the composite bacterial liquid of marine afipia felis and rhodopseudomonas coprophila composition, realize the synergistic degradation to high COD and sulfamethoxazole under suitable pH condition, so that COD removal rate still remains stable at higher level when concentration increases;End cooperate MBR membrane separation, high-efficiency biodegradation and high-efficiency solid-liquid separation are coupled to realize the efficient removal of sulfamethoxazole and COD in wastewater under low drug consumption, near neutral conditions.

Description

Technical Field

[0001] This invention relates to the field of wastewater biological treatment technology, and in particular to a process for the combined treatment of antibiotic wastewater using a composite microbial-MBR membrane. Background Technology

[0002] Sulfamethoxazole (SMX) is a broad-spectrum sulfonamide antibiotic widely used in human medicine, animal husbandry, and aquaculture. Its molecule contains an aromatic sulfonamide structure, making it difficult to completely remove by conventional activated sludge or anaerobic / aerobic combinations, often leaving residues in effluent and sludge. Even at sub-inhibitory concentrations, sulfamethoxazole exerts continuous selective pressure on environmental microbial communities, leading to the generation, accumulation, and spread of drug-resistant bacteria and resistance genes (ARGs). Upon entering receiving water bodies, it causes acute / chronic toxicity to algae and zooplankton, triggering ecological changes. Furthermore, sulfamethoxazole inhibits nitrification / denitrification and some anaerobic methanogenic microorganisms, reducing nitrogen removal and gas production efficiency in conventional processes, and altering sludge floc / EPS characteristics, inducing deterioration of sludge-water separation. Directly using membrane methods such as NF / RO to intercept sulfamethoxazole will create challenges in the reprocessing of highly concentrated solutions, and the interaction between sulfamethoxazole and soluble organic matter / colloids may exacerbate membrane fouling, increasing energy consumption and cleaning frequency. Therefore, it is necessary to develop a process that can continuously and stably remove sulfamethoxazole under near-neutral and low-drug-consumption conditions.

[0003] Traditional coagulation / adsorption methods mostly involve "transfer rather than elimination," which can easily lead to secondary pollution. While advanced oxidation can cleave sulfamethoxazole, it has high energy and drug consumption and complex byproduct management. Microbial degradation methods also suffer from poor stability of single bacterial species under antibiotic inhibition. Therefore, developing a process that can efficiently degrade and treat sulfamethoxazole is of great significance for the treatment of antibiotic wastewater. Summary of the Invention

[0004] In view of this, the present invention provides a process for the combined treatment of antibiotic wastewater by a composite microorganism-MBR membrane. The process utilizes domesticated marine afifefic bacteria and Rhodopseudomonas fecalis in combination with the MBR membrane treatment process, so that the synergistic metabolism of the two microorganisms can continue to play a role, thereby achieving efficient removal of sulfamethoxazole and COD from wastewater under low drug consumption and near-neutral conditions.

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

[0006] The first aspect of this invention provides a process for the combined treatment of antibiotic wastewater using a composite microbial-MBR membrane, comprising the following steps:

[0007] Step 1: The wastewater is fed into the reactor, and the initial COD concentration is controlled at 1500-2500 mg / L. When the COD removal rate is stable and ≥30%, the COD concentration of the influent is gradually increased to 8000-10000 mg / L. When the COD removal rate is stable and ≥40%, the COD concentration of the influent is gradually decreased to 1500-2000 mg / L. Activated sludge is added for pretreatment. When the COD removal rate is stable and ≥50%, the pretreatment is completed, and the microbial acclimatization stage begins.

[0008] Step 2: Add the activated compound microbial inoculum to the reactor, control the pH of the influent to 6.8-7.5, the COD concentration of the influent to 2000-2500 mg / L, and the hydraulic retention time to 15-20 h. When the COD removal rate is stable and ≥50%, gradually increase the COD concentration of the influent to 5700-6500 mg / L. When the COD removal rate is stable and ≥60%, proceed to the MBR membrane separation stage to obtain the treated wastewater.

[0009] In step one, the composite microbial solution includes marine afifeficial bacteria and fecal red erythromycetes.

[0010] Compared to existing technologies, this invention employs a combined process of "activated sludge pretreatment - composite microbial acclimatization - MBR membrane separation" to treat antibiotic wastewater, exhibiting strong resistance to shock loads and synergistic removal advantages for recalcitrant antibiotic pollutants. Firstly, this invention gradually increases the influent COD from 1500-2000 mg / L to 8000-10000 mg / L, then decreases it back to 1500-2000 mg / L. The dynamic regulation of COD removal rates, progressively advancing to 30%, 40%, and 50% or higher, allows for the segmented acclimatization and toxicity screening of activated sludge. This prioritizes the elimination of antibiotic-sensitive and metabolically weak microbial communities, while enriching antibiotic-resistant and high-organic-load-tolerant functional microbial communities. This effectively buffers the inhibitory effects of antibiotics and their metabolites on the biological system. Furthermore, this invention introduces activated composite microbial solutions into the reactor, including *Aphtheria marinum*, which possesses strong organic matter degradation and biofilm formation capabilities, and *Rhodopseudomonas faecalis*, which exhibits good tolerance and synergistic degradation of multiple antibiotics. Both bacteria secrete extracellular enzymes and polymers to construct a dense and stable biofilm structure. Under neutral conditions, this efficiently removes biodegradable organic matter while simultaneously breaking down sulfamethoxazole molecules through co-metabolism. The amide bond, aromatic ring, and other functional structures enhance the biodegradability of antibiotics and their intermediates, allowing the COD removal rate to be steadily increased from over 50% to 5700-6500 mg / L while maintaining a stable removal level of over 60%. Finally, in conjunction with an MBR membrane separation unit, under operating conditions of high sludge age, high sludge-water separation efficiency, and high biomass concentration, the system fully leverages the deep degradation capabilities of the composite microbial system. Furthermore, the membrane retention effect reduces the risk of residual antibiotics and microbial resistance genes being discharged. The membrane module utilizes mechanical sieving and retention to achieve solid-liquid separation of wastewater and photosynthetic bacteria mixture, thus realizing the synergistic and efficient removal of organic pollutants and antibiotic-resistant pollutants from antibiotic wastewater. The effluent quality is stable, and the system's shock resistance and long-term operational stability are significantly superior to conventional activated sludge processes.

[0011] Preferably, the volume ratio of marine afifuvianella and fecal red rosmotherum in the compound microbial inoculum is 1:1 to 1:1.2.

[0012] More preferably, the viable count of the marine afifuvius bacteria is 5 × 10⁻⁶. 8 CFU / mL - 1×10 9 CFU / mL.

[0013] More preferably, the marine afifovella is designated as SMHCC D51861.

[0014] More preferably, the Rhodopseudomonas fecalis is designated as SMHCC D51958.

[0015] More preferably, the viable count of *Rhodopseudomonas fecalis* is 1 × 10⁻⁶. 8 CFU / mL - 5 × 10 8 CFU / mL.

[0016] Preferably, in step one, the settling ratio (SV) of the activated sludge is 15%-40%, the mass concentration of volatile suspended solids (MLVSS) it contains is 0.6-0.75 g / L, and the mass concentration of liquid suspended solids (MLSS) it contains is 3-6 g / L.

[0017] Preferably, in step one, the operation of gradually increasing the wastewater COD concentration to 8000-10000 mg / L specifically includes the following steps: when the COD removal rate is stable and all are ≥30%, the influent concentration is increased to 8000-10000 mg / L at an increasing rate of 800-1200 mg / L, and stabilized for 4-6 days.

[0018] Preferably, in step one, the operation of gradually reducing the wastewater COD concentration to 1500-2000 mg / L specifically includes the following steps: when the COD removal rate is stable and all are ≥40%, the influent concentration is gradually reduced to 8000-10000 mg / L at a rate of 1000-1500 mg / L, and stabilized for 4-6 days.

[0019] Preferably, in step one, the inlet water temperature of the reactor is 32-33℃.

[0020] Preferably, in step one, the pH of the reactor influent is 7-8.

[0021] Preferably, in step two, the operation of gradually increasing the COD influent concentration to 5700-6500 mg / L specifically includes the following steps: when the COD removal rate is stable and ≥50%, the influent concentration is increased to 5700-6500 mg / L at an increase rate of 500-600 mg / L, and stabilized for 3-5 days.

[0022] Preferably, in step one, the amount of activated sludge added is 3%-5% of the reactor capacity.

[0023] Preferably, in step two, the amount of the composite microbial inoculum added is 10%-15% of the mass of the activated sludge.

[0024] Preferably, in step two, the MBR membrane separation stage uses a pore size of 100-200 nm and an effective filtration area of ​​0.4-0.8 m². 2 Hollow fiber tubular membrane.

[0025] More preferably, in step two, the hollow fiber tubular membrane is made of PVDF.

[0026] In summary, this invention provides a method for targeted acclimatization and toxicity screening of activated sludge through COD gradient adjustment and removal rate control, thereby constructing a microbial community resistant to sulfamethoxazole shock. Furthermore, it introduces a composite bacterial solution composed of marine afifivobacterium and Rhodopseudomonas fecalis, achieving synergistic degradation of high COD and sulfamethoxazole under suitable pH conditions, ensuring that the COD removal rate remains stable at a high level even as the concentration increases. Finally, it incorporates MBR membrane separation at the end, coupling efficient biodegradation with efficient solid-liquid separation. This reduces the risk of secondary pollution and improves system operational stability and effluent quality without relying on large amounts of chemical reagents, thus effectively overcoming the problems of high energy and chemical consumption, difficulty in controlling byproducts, and poor stability of single bacterial strains in existing processes. Detailed Implementation

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] The preparation methods of the composite microbial bacterial solutions used in the following embodiments and comparative examples include the following steps:

[0029] Under aseptic conditions, take an ampoule containing lyophilized marine afifovella powder, open it after surface sterilization, and use a sterile pipette to add 0.5 mL of the prepared liquid marine broth culture medium into the ampoule. Gently pipette to completely dissolve the lyophilized powder and prepare the initial bacterial suspension.

[0030] Take a small amount of bacterial suspension and inoculate it onto a marine agar plate using the streak plate method. Incubate the plate in a constant temperature incubator and invert it for 36 hours at 25°C. Once a morphological array grows on the surface of the plate and uniform single colonies are prepared at the edges, the activation step is complete.

[0031] Preparation of primary seed culture: Pick a single dominant colony from the activated plate and transfer it to a 250 mL Erlenmeyer flask containing 50 mL of liquid marine broth medium. Place the flask in a shaker and incubate at 25°C and 180 rpm for 16 h to obtain the culture medium.

[0032] Expanded culture: At a culture volume of 3% (v / v), transfer the culture medium to a 250 mL fermentation vessel containing fresh seed culture medium. Incubate at 25°C with shaking at 180 rpm. Continue incubation until the viable cell count reaches 5 × 10⁻⁶. 8 CFU / mL - 1×10 9CFU / mL, terminate the culture, and obtain marine afifovella culture medium.

[0033] The liquid marine broth culture medium consists of the following components: 5.0 g peptone, 1.0 g yeast extract, 0.1 g ferric citrate, 19.45 g sodium chloride, 5.90 g magnesium chloride, 3.24 g magnesium sulfate, 1.80 g calcium chloride, 0.55 g potassium chloride, 0.16 g sodium bicarbonate, and the remainder is water.

[0034] The preparation method of the liquid marine broth culture medium is as follows: dissolve the above components in water, heat and stir to aid dissolution, adjust the pH value to 7.6 (25℃) after cooling, and then perform autoclaving (121℃, 15min) for later cooling.

[0035] The method for preparing the marine agar solid plate is as follows: 15.0 g / L of agar powder is added to the liquid marine broth culture medium, heated to boiling until completely dissolved, sterilized, and then cooled to about 50°C before being poured into plates.

[0036] Fresh seed culture medium: per 1L: peptone: 5.0g; yeast extract: 1.0g; ferric citrate: 0.1g; sodium chloride: 19.45g; magnesium chloride: 5.90g; magnesium sulfate: 3.24g; calcium chloride: 1.80g; potassium chloride: 0.55g; sodium bicarbonate: 0.16g; add deionized water to a final volume of 1000mL.

[0037] Preparation conditions for fresh seed culture medium: After the above components are dissolved, the pH value needs to be adjusted to 7.6 (25℃), and then sterilized by autoclaving at 121℃ for 15 minutes before use.

[0038] Similarly, *Rhodopseudomonas fecalis* was cultured according to the method described in CN102816797A. When the number of viable bacteria in the culture reached 1×10⁻⁶... 8 CFU / mL - 5 × 10 8 CFU / mL, terminate the culture, and obtain a culture medium of Rhodopseudomonas fecalis.

[0039] The MBR membranes used in the following embodiments have a pore size of 100-200 nm and an effective filtration area of ​​0.4-0.8 m². 2 PVDF hollow fiber tubular membrane.

[0040] Example 1

[0041] This embodiment provides a process for the combined treatment of antibiotic wastewater using a composite microbial-MBR membrane, specifically including the following:

[0042] Step 1: The wastewater is fed into the reactor, with the initial COD concentration controlled at 2250 mg / L, pH at 7.4, and influent temperature at 33℃. When the COD removal rate is stable and ≥30%, the influent concentration is increased to 9000 mg / L at a rate of 1000 mg / L and stabilized for 4 days. When the COD removal rate is stable and ≥40%, the influent concentration is decreased to 1800 mg / L at a rate of 1000 mg / L and stabilized for 5 days. Activated sludge, accounting for 3% of the reactor capacity, is added for pretreatment. When the COD removal rate is stable and ≥50%, the pretreatment is complete, and the process enters the microbial acclimatization stage.

[0043] Step 2: Add the activated composite microbial solution to the reactor, control the pH of the influent to 7.3, the COD concentration of the influent to 2200 mg / L, and the hydraulic retention time to 18 h. When the COD removal rate is stable and ≥50%, gradually increase the COD concentration of the influent to 6200 mg / L. When the COD removal rate is stable and ≥60%, proceed to the MBR membrane separation stage to obtain the treated wastewater. The amount of the composite microbial solution added is 12% of the mass of the activated sludge.

[0044] In step one, the volume ratio of *A. marineis* and *Rhodopseudomonas fecalis* in the composite microbial culture solution is 1:1; wherein the viable count of *A. marineis* in the culture solution is 8 × 10⁻⁶. 8 CFU / mL; the viable count of *Rhodopseudomonas faecalis* in the bacterial suspension was 2 × 10⁻⁶. 8 CFU / mL.

[0045] The activated sludge has a settling ratio (SV) of 18%, contains 0.65 g / L of volatile suspended solids (MLVSS), and contains 4 g / L of liquid suspended solids (MLSS).

[0046] According to statistics, the concentration of sulfamethoxazole in the wastewater before treatment in this embodiment was 178.35 mg / L, and the COD concentration was 2250 mg / L; the concentration of sulfamethoxazole in the wastewater after treatment was 12.46 mg / L, and the COD concentration was 520 mg / L.

[0047] Example 2

[0048] This embodiment provides a process for the combined treatment of antibiotic wastewater using a composite microbial-MBR membrane, specifically including the following:

[0049] Step 1: The wastewater is fed into the reactor, with the initial COD concentration controlled at 2500 mg / L, pH at 7.2, and influent temperature at 32℃. When the COD removal rate is stable and ≥30%, the influent concentration is increased by 900 mg / L to 9000 mg / L and stabilized for 4 days. When the COD removal rate is stable and ≥40%, the influent concentration is decreased by 1000 mg / L to 1800 mg / L and stabilized for 5 days. Activated sludge, accounting for 4% of the reactor capacity, is added for pretreatment. When the COD removal rate is stable and ≥50%, the pretreatment is complete, and the process enters the microbial acclimatization stage.

[0050] Step 2: Add the activated composite microbial solution to the reactor, control the pH of the influent to 7.3, the COD concentration of the influent to 2400 mg / L, and the hydraulic retention time to 15 h. When the COD removal rate is stable and ≥50%, gradually increase the COD concentration of the influent to 6200 mg / L. When the COD removal rate is stable and ≥60%, proceed to the MBR membrane separation stage to obtain the treated wastewater. The amount of the composite microbial solution added is 12% of the mass of the activated sludge.

[0051] In step one, the volume ratio of *A. marineis* and *Rhodopseudomonas fecalis* in the composite microbial culture solution is 1:1.1; wherein the viable count of *A. marineis* in the culture solution is 8 × 10⁻⁶. 8 CFU / mL; the viable count of *Rhodopseudomonas faecalis* in the bacterial suspension was 2 × 10⁻⁶. 8 CFU / mL.

[0052] The activated sludge has a settling ratio (SV) of 25%, contains 0.63 g / L of volatile suspended solids (MLVSS), and contains 5 g / L of liquid suspended solids (MLSS).

[0053] According to statistics, the concentration of sulfamethoxazole in the wastewater before treatment in this embodiment was 182.31 mg / L, and the COD concentration was 2500 mg / L; the concentration of sulfamethoxazole in the wastewater after treatment was 14.32 mg / L, and the COD concentration was 540 mg / L.

[0054] Example 3

[0055] This embodiment provides a process for the combined treatment of antibiotic wastewater using a composite microbial-MBR membrane, specifically including the following:

[0056] Step 1: The wastewater is fed into the reactor, with the initial COD concentration controlled at 1950 mg / L, pH at 7.7, and influent temperature at 32℃. When the COD removal rate is stable and ≥30%, the influent concentration is increased by 800 mg / L to 9000 mg / L and stabilized for 4 days. When the COD removal rate is stable and ≥40%, the influent concentration is decreased by 1000 mg / L to 1800 mg / L and stabilized for 5 days. Activated sludge, accounting for 3% of the reactor capacity, is added for pretreatment. When the COD removal rate is stable and ≥50%, the pretreatment is complete, and the process enters the microbial acclimatization stage.

[0057] Step 2: Add the activated composite microbial solution to the reactor, control the pH of the influent to 7.3, the COD concentration of the influent to 2200 mg / L, and the hydraulic retention time to 18 h. When the COD removal rate is stable and ≥50%, gradually increase the COD concentration of the influent to 6200 mg / L. When the COD removal rate is stable and ≥60%, proceed to the MBR membrane separation stage to obtain the treated wastewater. The amount of the composite microbial solution added is 12% of the mass of the activated sludge.

[0058] In step one, the volume ratio of *A. marineis* and *Rhodopseudomonas fecalis* in the composite microbial culture solution is 1:1.2; wherein the viable count of *A. marineis* in the culture solution is 8 × 10⁻⁶. 8 CFU / mL; the viable count of *Rhodopseudomonas faecalis* in the bacterial suspension was 2 × 10⁻⁶. 8 CFU / mL.

[0059] The activated sludge has a settling ratio (SV) of 30%, contains 0.65 g / L of volatile suspended solids (MLVSS), and contains 4 g / L of liquid suspended solids (MLSS).

[0060] According to statistics, the concentration of sulfamethoxazole in the wastewater before treatment in this embodiment was 188.37 mg / L, and the COD concentration was 1950 mg / L; the concentration of sulfamethoxazole in the wastewater after treatment was 15.84 mg / L, and the COD concentration was 520 mg / L.

[0061] Example 4

[0062] This embodiment provides a process for the combined treatment of antibiotic wastewater using a composite microbial-MBR membrane, specifically including the following:

[0063] Step 1: The wastewater is fed into the reactor, with the initial COD concentration controlled at 2350 mg / L, pH at 7.6, and influent temperature at 33℃. When the COD removal rate is stable and ≥30%, the influent concentration is increased to 9000 mg / L at a rate of 800-1200 mg / L and stabilized for 5 days. When the COD removal rate is stable and ≥40%, the influent concentration is decreased to 1800 mg / L at a rate of 1000 mg / L and stabilized for 5 days. Activated sludge, accounting for 3.5% of the reactor capacity, is added for pretreatment. When the COD removal rate is stable and ≥50%, the pretreatment is complete, and the process enters the microbial acclimatization stage.

[0064] Step 2: Add the activated composite microbial solution to the reactor, control the pH of the influent to 7.3, the COD concentration of the influent to 2200 mg / L, and the hydraulic retention time to 20 h. When the COD removal rate is stable and ≥50%, gradually increase the COD concentration of the influent to 6200 mg / L. When the COD removal rate is stable and ≥60%, proceed to the MBR membrane separation stage to obtain the treated wastewater. The amount of the composite microbial solution added is 12% of the mass of the activated sludge.

[0065] In step one, the volume ratio of *A. marineis* and *Rhodopseudomonas fecalis* in the composite microbial culture solution is 1:1; wherein the viable count of *A. marineis* in the culture solution is 8 × 10⁻⁶. 8 CFU / mL; the viable count of *Rhodopseudomonas faecalis* in the bacterial suspension was 2 × 10⁻⁶. 8 CFU / mL.

[0066] The activated sludge has a settling ratio (SV) of 30%, contains 0.6 g / L of volatile suspended solids (MLVSS), and contains 5 g / L of liquid suspended solids (MLSS).

[0067] According to statistics, the concentration of sulfamethoxazole in the wastewater before treatment in this embodiment was 193.27 mg / L and the COD concentration was 2350 mg / L; the concentration of sulfamethoxazole in the wastewater after treatment was 17.33 mg / L and the COD concentration was 550 mg / L.

[0068] Example 5

[0069] This embodiment provides a process for the combined treatment of antibiotic wastewater using a composite microbial-MBR membrane, specifically including the following:

[0070] Step 1: The wastewater is fed into the reactor, with the initial COD concentration controlled at 2250 mg / L, pH at 7.4, and influent temperature at 33℃. When the COD removal rate is stable and ≥30%, the influent concentration is increased to 9000 mg / L at a rate of 800-1200 mg / L and stabilized for 4 days. When the COD removal rate is stable and ≥40%, the influent concentration is decreased to 1700 mg / L at a rate of 1000 mg / L and stabilized for 5 days. Activated sludge, accounting for 3% of the reactor capacity, is added for pretreatment. When the COD removal rate is stable and ≥50%, the pretreatment is complete, and the process enters the microbial acclimatization stage.

[0071] Step 2: Add the activated composite microbial solution to the reactor, control the pH of the influent to 7.3, the COD concentration of the influent to 2000 mg / L, and the hydraulic retention time to 18 h. When the COD removal rate is stable and ≥50%, gradually increase the COD concentration of the influent to 6000 mg / L. When the COD removal rate is stable and ≥60%, proceed to the MBR membrane separation stage to obtain the treated wastewater. The amount of the composite microbial solution added is 15% of the mass of the activated sludge.

[0072] In step one, the volume ratio of *A. marineis* and *Rhodopseudomonas fecalis* in the composite microbial culture solution is 1:1.2; wherein the viable count of *A. marineis* in the culture solution is 8 × 10⁻⁶. 8 CFU / mL; the viable count of *Rhodopseudomonas faecalis* in the bacterial suspension was 2 × 10⁻⁶. 8 CFU / mL.

[0073] The activated sludge has a settling ratio (SV) of 15%, contains 0.7 g / L of volatile suspended solids (MLVSS), and contains 5 g / L of liquid suspended solids (MLSS).

[0074] According to statistics, the concentration of sulfamethoxazole in the wastewater before treatment in this embodiment was 190.06 mg / L and the COD concentration was 2250 mg / L; the concentration of sulfamethoxazole in the wastewater after treatment was 16.83 mg / L and the COD concentration was 550 mg / L.

[0075] Comparative Example 1

[0076] This comparative example provides a process for the combined treatment of antibiotic wastewater using a composite microbial-MBR membrane, differing from Example 1 in that: the composite microbial bacterial solution is replaced with an equal amount of *A. marineis* bacterial solution; the viable count of the *A. marineis* bacterial solution is 8 × 10⁻⁶. 8 CFU / mL; other processes and parameters remain unchanged and will not be repeated here.

[0077] According to statistics, the concentration of sulfamethoxazole in the wastewater before treatment in this embodiment was 178.35 mg / L, and the COD concentration was 2250 mg / L; the concentration of sulfamethoxazole in the wastewater after treatment was 74.85 mg / L, and the COD concentration was 980 mg / L.

[0078] Comparative Example 2

[0079] This comparative example provides a process for the combined treatment of antibiotic wastewater using a composite microbial-MBR membrane, differing from Example 1 in that: the composite microbial culture is replaced with an equal amount of *Rhodopseudomonas faecalis* culture; the viable count of *Rhodopseudomonas faecalis* in the culture is 2 × 10⁻⁶. 8 CFU / mL; other processes and parameters remain unchanged and will not be repeated here.

[0080] According to statistics, the concentration of sulfamethoxazole in the wastewater before treatment in this embodiment was 178.35 mg / L, and the COD concentration was 2250 mg / L; the concentration of sulfamethoxazole in the wastewater after treatment was 83.27 mg / L, and the COD concentration was 950 mg / L.

[0081] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A process for treating antibiotic wastewater using a composite microbial-MBR membrane co-treatment method, characterized in that: Includes the following steps: Step 1: The wastewater is fed into the reactor, and the initial COD concentration is controlled at 1500-2500 mg / L. When the COD removal rate is stable and ≥30%, the COD concentration of the influent is gradually increased to 8000-10000 mg / L. When the COD removal rate is stable and ≥40%, the COD concentration of the influent is gradually decreased to 1500-2000 mg / L. Activated sludge is added for pretreatment. When the COD removal rate is stable and ≥50%, the pretreatment is completed, and the microbial acclimatization stage begins. Step 2: Add the activated compound microbial inoculum into the reactor, control the pH of the influent to 6.8-7.5, the COD concentration of the influent to 2000-2500 mg / L, and the hydraulic retention time to 15-20 h. When the COD removal rate is stable and ≥50%, gradually increase the COD concentration of the influent to 5700-6500 mg / L. When the COD removal rate is stable and ≥60%, proceed to the MBR membrane separation stage to obtain the treated wastewater. In step one, the concentration of sulfamethoxazole in the wastewater before treatment is 178.35 mg / L-193.27 mg / L; In step two, the composite microbial culture includes *A. marineis* and *Rhodopseudomonas faecalis*; the volume ratio of *A. marineis* to *Rhodopseudomonas faecalis* in the composite microbial culture is 1:1 to 1:1.2; and the viable count of *A. marineis* is 5 × 10⁻⁶. 8 CFU / mL - 1×10 9 CFU / mL; the viable count of the *Rhodopseudomonas fecalis* was 1 × 10⁻⁶. 8 CFU / mL - 5 × 10 8 CFU / mL.

2. The process for combined treatment of antibiotic wastewater using a composite microbial-MBR membrane as described in claim 1, characterized in that: In step one, the settling ratio (SV) of the activated sludge is 15%-40%, the mass concentration of volatile suspended solids (MLVSS) it contains is 0.6-0.75 g / L, and the mass concentration of liquid suspended solids (MLSS) it contains is 3-6 g / L.

3. The process for combined treatment of antibiotic wastewater using a composite microbial-MBR membrane as described in claim 1, characterized in that: In step one, the operation of gradually increasing the wastewater COD concentration to 8000-10000 mg / L specifically includes the following steps: when the COD removal rate is stable and ≥30%, the influent concentration is increased to 8000-10000 mg / L at an increase rate of 800-1200 mg / L, and stabilized for 4-6 days.

4. The process for combined treatment of antibiotic wastewater using a composite microbial-MBR membrane as described in claim 1, characterized in that: In step one, the operation of gradually reducing the COD concentration of wastewater to 1500-2000 mg / L specifically includes the following steps: when the COD removal rate is stable and all are ≥40%, the influent concentration is gradually reduced to 1500-2000 mg / L at a rate of 1000-1500 mg / L, and stabilized for 4-6 days.

5. The process for combined treatment of antibiotic wastewater using a composite microbial-MBR membrane as described in claim 1, characterized in that: In step one, the inlet water temperature of the reactor is 32-33℃; In step one, the pH of the reactor influent is 7-8.

6. The process for combined treatment of antibiotic wastewater using a composite microbial-MBR membrane as described in claim 1, characterized in that: Step two, the operation of gradually increasing the COD influent concentration to 5700-6500 mg / L specifically includes the following steps: when the COD removal rate is stable and ≥50%, the influent concentration is increased to 5700-6500 mg / L at an increase rate of 500-600 mg / L, and stabilized for 3-5 days.

7. The process for combined treatment of antibiotic wastewater using a composite microbial-MBR membrane as described in claim 1, characterized in that: In step one, the amount of activated sludge added is 3%-5% of the reactor capacity; In step two, the amount of the composite microbial inoculum added is 10%-15% of the mass of the activated sludge.

8. The process for combined treatment of antibiotic wastewater using a composite microbial-MBR membrane as described in claim 1, characterized in that: In step two, the MBR membrane separation stage uses a pore size of 100-200 nm and an effective filtration area of ​​0.4-0.8 m². 2 Hollow fiber tubular membrane.