A method and system for purifying high-salinity wastewater

Abstract

This invention relates to a method and system for purifying high-salinity wastewater. The method includes: adding a saline solution to be treated to a reaction chamber of a bioreactor; placing the cathode and anode of the bioreactor in the saline solution; inoculating the anode with microorganisms; starting the bioreactor and applying an alternating electric field to the cathode and anode to purify the saline solution; wherein the microorganisms include sulfate-reducing bacteria; the salinity of the saline solution is 2‰-8‰; and the inorganic salts in the saline solution include sulfates. This invention, by applying an alternating electric field to the microorganisms, stimulates and enhances their metabolic activity, thereby improving the removal efficiency of recalcitrant pollutants from high-salinity wastewater. It is suitable for treating mine water of different compositions and concentrations.

Description

Technical Field

[0001] This invention belongs to the field of water treatment, specifically relating to a method and system for purifying high-salinity wastewater. Background Technology

[0002] High-salinity wastewater refers to wastewater containing organic matter and at least 3.5 wt% total dissolved solids (TDS), including high-salinity domestic wastewater and high-salinity industrial wastewater. The main sources of high-salinity wastewater include concentrated brine produced during seawater desalination, high-salinity wastewater directly discharged during industrial production, and brine generated from the recycling of industrial wastewater. The types of inorganic ions contained in most industrial wastewater vary depending on the industry. For example, industrial wastewater discharged from steel mills, coal chemical plants, and petroleum industries contains relatively high levels of calcium, magnesium, potassium, sodium, chloride, and carbonate ions.

[0003] Biological treatment methods are economical and harmless, but high salt concentrations in wastewater lead to high osmotic pressure, causing dehydration of microbial cells and protoplasmic separation. Furthermore, high salt concentrations can reduce dehydrogenase activity due to salting out, inhibiting microbial growth and posing challenges to biological treatment. CN110697878A discloses a method for treating high-salt wastewater and recovering nutrients using a microbial desalination battery. This method utilizes a novel air cathode catalyst material, PMo / CB, to construct a desalination battery and optimizes the anode colony structure through microbial community domestication, thereby improving the energy for organic matter degradation and nutrient recovery.

[0004] CN118651956A discloses a method for treating marine aquaculture wastewater using microbial electrochemical coupling anaerobic technology. This method employs a microbial electrochemical system constructed using a microbial fuel cell (MFC) and a microbial electrolyzer (MEC), utilizing anaerobic microorganisms to treat the wastewater. The organic matter is degraded through three stages: hydrolysis and fermentation, hydrogen and acetic acid production, and methanogenesis. However, this method alone cannot simultaneously and efficiently remove multiple complex pollutants from marine aquaculture wastewater using anaerobic biological treatment. This is because, firstly, the high applied voltage (>1V) of the bioelectrochemical system easily exacerbates the oxygen evolution reaction at the electrode anode, reducing the biofilm degradation effect. Secondly, the high-salt environment easily leads to microbial cell rupture, inhibiting microbial metabolism and reducing microbial activity. Summary of the Invention

[0005] The purpose of this invention is to improve the pollutant removal efficiency of microorganisms under high salt concentration conditions.

[0006] To achieve the above objectives, a first aspect of the present invention provides a method for purifying high-salinity wastewater, the method comprising: A saline solution to be treated is added to the reaction chamber of a bioreactor, and the cathode and anode of the bioreactor are placed in the saline solution; the anode is inoculated with microorganisms. The bioreactor is started, and an alternating electric field is applied to the cathode and the anode to purify the saline solution; The microorganisms include sulfate-reducing bacteria; The salinity of the salt-containing solution is 2‰-8‰; the inorganic salts in the salt-containing solution include sulfates.

[0007] Optionally, the purification includes a microbial adaptation stage and a microbial treatment stage performed sequentially; the alternating electric field conditions of the microbial adaptation stage include: an electric field strength of 0.1-1 V / cm and a frequency of 5-20 Hz; and an operating time of 10-20 days; the alternating electric field conditions of the microbial treatment stage include: an electric field strength of 1-5 V / cm and a frequency of 20-50 Hz. Optionally, the alternating electric field applied during the microbial treatment stage is pulsed, with an energizing time of 10-20 minutes and a pulse duty cycle of 30%-80%.

[0008] Optionally, the concentration of sulfate in the salt solution is 500-2000 mg / L.

[0009] Optionally, the salt solution also contains NH4. + The ammonia nitrogen concentration is 20-100 mg / L.

[0010] Optionally, the bioreactor uses intermittent water feeding; the ambient temperature in the reaction chamber is 20-40 ℃, preferably 15-30 ℃; and the pH value of the salt solution is 6-9.

[0011] Optionally, the microorganisms are obtained through screening, domestication, and enrichment using a method including the following steps: S1. The microorganism is inoculated into a culture medium containing a first salinity and a first sulfate concentration for cultivation and domestication to obtain the first microorganism; the first salinity is 2‰-4‰ and the first sulfate concentration is 500-800 mg / L; S2. The first microorganism is inoculated into a culture medium containing a second salinity and a first sulfate concentration for cultivation and acclimatization. After the microorganism grows stably, the microorganism is inoculated into a culture medium containing a second salinity and a second sulfate concentration for cultivation and acclimatization to obtain a second microorganism; the second salinity is 5‰-6‰ and the second sulfate concentration is 900-1200 mg / L. S3. The second microorganism is inoculated into a culture medium containing a third salinity and a first sulfate concentration for cultivation and acclimatization. Then, the microorganism is inoculated into a culture medium with an increasing concentration gradient of third salinity and sulfate for cultivation and acclimatization until the sulfate concentration is increased to the third sulfate concentration to obtain the third microorganism. The third salinity is 7‰-8‰ and the third sulfate concentration is 1500-2000 mg / L. S4. The third microorganism is inoculated into the culture medium in step S1 for domestication, and then steps S2-S3 are performed sequentially, 3-4 times.

[0012] Optionally, the thickness of the microbial film inoculated on the surface of the anode is 0.1-3 cm.

[0013] A second aspect of the present invention provides a high-salinity wastewater purification system, the system comprising a bioreactor and an alternating power supply, the bioreactor comprising a reaction chamber and a cathode and an anode adapted to be disposed in the reaction chamber; the cathode and the anode are respectively electrically connected to the alternating power supply; and the surface of the anode is covered with microorganisms; the microorganisms include sulfate-reducing bacteria.

[0014] Optionally, the reaction chamber is provided with an inlet at the bottom or lower part and an outlet at the top or upper part; optionally, the inlet is connected to an inlet pool and the outlet is connected to an outlet pool; optionally, the anode is selected from one or more of carbon cloth and carbon felt; the cathode is made of one or more of stainless steel, titanium, copper and aluminum.

[0015] Through the above technical solution, the present invention applies an alternating electric field to microorganisms to stimulate and enhance their metabolic activity, thereby improving the removal efficiency of microorganisms for recalcitrant pollutants (such as sulfates) in high-salt wastewater. It is suitable for treating mine water with different compositions and concentrations.

[0016] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0017] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of a high-salt wastewater purification system in some embodiments of the present invention.

[0018] Explanation of reference numerals in the attached figures: 110. Reaction chamber; 121. Inlet; 131. Outlet; 200. Alternating power supply; 310. Cathode; 320. Anode. Detailed Implementation

[0019] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0020] A first aspect of the present invention provides a method for purifying high-salinity wastewater, the method comprising: A saline solution to be treated is added to the reaction chamber of a bioreactor, and the cathode and anode of the bioreactor are placed in the saline solution; the anode is inoculated with microorganisms. The bioreactor is started, and an alternating electric field is applied to the cathode and the anode to purify the saline solution; The microorganisms include sulfate-reducing bacteria; The salinity of the salt-containing solution is 2‰-8‰; the inorganic salts in the salt-containing solution include sulfates.

[0021] This invention applies an alternating electric field to microorganisms to stimulate and enhance their metabolic activity, thereby improving the removal efficiency of recalcitrant pollutants (such as sulfates) in high-salt wastewater. It is suitable for treating mine water of different compositions and concentrations.

[0022] The high-salinity wastewater in this invention includes, but is not limited to, high-salinity domestic wastewater and high-salinity industrial wastewater, such as high-salinity mine water. Mine water refers to wastewater generated during the mining of coal seams or other mineral deposits, which contains a large amount of difficult-to-treat sulfates and has a high salinity. In high-salinity wastewater, sulfate ions are converted to divalent sulfur by sulfate-reducing bacteria, existing in the form of sulfides or hydrogen sulfide.

[0023] The inventors discovered through research that by applying an alternating electric field to the microbial purification process, the microorganisms underwent at least the following changes: Increased cell membrane permeability: Alternating electric fields can cause voltage changes in the cell membrane, leading to the formation of temporary micropores on the cell membrane; these micropores increase the permeability of the cell membrane, which is conducive to the transmembrane transport of nutrients and metabolites, thereby accelerating the metabolic process of microorganisms; Increased enzyme activity: An electric field of appropriate strength can alter the conformation of certain enzyme molecules, making their active sites more readily exposed, thereby improving the enzyme's catalytic efficiency; this is especially important for key enzymes involved in the degradation of pollutants in microorganisms. Accelerated cellular energy metabolism: Alternating electric fields may stimulate the activity of ATP synthase in microbial cells, promoting ATP production and providing more energy for metabolic activities. Biofilm structure optimization: The electric field can affect the formation process of microbial films, making their structure more porous, which is conducive to the contact between pollutants and microorganisms and improves treatment efficiency; Enhanced intercellular communication: Alternating electric fields may promote intercellular signal transduction in microbial communities, enhance community synergy, and thus improve the overall pollutant degradation capacity; Accelerated ion movement: Under the influence of an electric field, the movement of ions in aqueous solution is accelerated, which helps to increase the contact frequency between pollutant molecules and microorganisms, thus accelerating the degradation process; Enhanced microbial tolerance: Microorganisms that grow under alternating electric fields for a long time may undergo adaptive changes, enhancing their tolerance to high-salt environments, thereby maintaining high metabolic activity under harsh conditions.

[0024] In some embodiments of the present invention, the purification includes a microbial adaptation stage and a microbial treatment stage performed sequentially. During the microbial adaptation stage, the microorganisms also treat contaminants such as sulfates in the saline solution. To avoid stress on the microorganisms from the alternating electric field, the electric field during the adaptation stage is set to low frequency and low intensity. The AC power supply used to apply the alternating electric field is a sinusoidal AC power supply with adjustable output frequency and voltage amplitude.

[0025] In some embodiments of the present invention, the alternating electric field conditions during the microbial adaptation phase include: an electric field strength of 0.1-1 V / cm, a frequency of 5-20 Hz, and an operating time of 10-20 days.

[0026] In some embodiments of the present invention, the alternating electric field conditions during the microbial treatment stage include: an electric field strength of 1-5 V / cm and a frequency of 20-50 Hz.

[0027] By adjusting the alternating electric field parameters in stages—using lower intensity and frequency during the microbial adaptation phase and gradually increasing them during the treatment phase—the inhibitory effect of high-salt environment on microbial metabolic activity was overcome. This significantly improved the metabolic activity and pollutant removal efficiency of sulfate-reducing bacteria in the treatment of high-salt mine water, achieving optimal treatment results. This low-frequency alternating electric field stimulation method not only enhances the tolerance and metabolic capacity of microorganisms but also offers advantages in energy consumption. Furthermore, this flexible operation allows the system to better adapt to mine water with different compositions and concentrations.

[0028] In some embodiments of the present invention, the alternating electric field applied during the microbial treatment stage is pulsed, with an energizing time of 10-20 minutes and a pulse duty cycle of 30%-80%. By alternating energizing and de-energizing, the high activity of the microorganisms can be maintained while reducing energy consumption.

[0029] In some embodiments of the present invention, the concentration of sulfate in the saline solution is 500-2000 mg / L. In the present invention, the sulfate in the saline solution (in the form of SO42-) 2- The concentration of (the sample) was measured according to standard methods.

[0030] In some embodiments of the present invention, the salt solution also contains NH4. + The ammonia nitrogen concentration is 20-100 mg / L. The ammonia nitrogen concentration (NH3-N) in the saline solution is calculated using conventional methods.

[0031] In some embodiments of the present invention, the bioreactor adopts intermittent water inlet. For example, the operating conditions such as electric field parameters and hydraulic retention time are adjusted according to the effluent quality to optimize the treatment effect. When the effluent meets the discharge standards, the treated water is discharged and new high-salt mine water to be treated is added to circulate the treatment process.

[0032] In some embodiments of the present invention, in order to improve the efficiency of microbial treatment of saline solutions, the ambient temperature in the reaction chamber is 20-40 ℃, preferably 15-30 ℃; and the pH value of the saline solution is 6-9.

[0033] In some embodiments of the present invention, the microorganisms are obtained through screening, domestication, and enrichment using a method comprising the following steps: S1. The microorganism is inoculated into a culture medium containing a first salinity and a first sulfate concentration for cultivation and domestication to obtain the first microorganism; the first salinity is 2‰-4‰ and the first sulfate concentration is 500-800 mg / L; S2. The first microorganism is inoculated into a culture medium containing a second salinity and a first sulfate concentration for cultivation and acclimatization. After the microorganism grows stably, it is inoculated into a culture medium containing a second salinity and a second sulfate concentration for cultivation and acclimatization to obtain a second microorganism; the second salinity is 5‰-6‰ and the second sulfate concentration is 900-1200 mg / L. S3. The second microorganism is inoculated into a culture medium containing a third salinity and a first sulfate concentration for cultivation and acclimatization. Then, the microorganism is inoculated into a culture medium with an increasing concentration gradient of third salinity and sulfate for cultivation and acclimatization until the sulfate concentration is increased to the third sulfate concentration (for example, the sulfate concentration can be increased to the second sulfate concentration first, and then increased to the third sulfate concentration; or the sulfate concentration can be increased from the second sulfate concentration to any other sulfate concentration between the second and third sulfate concentrations, and then increased to the third sulfate concentration), to obtain the third microorganism; the third salinity is 7‰-8‰, and the third sulfate concentration is 1500-2000 mg / L; S4. The third microorganism is inoculated into the culture medium in step S1 for domestication, and then steps S2-S3 are performed sequentially, 3-4 times.

[0034] In some embodiments of the present invention, the method further includes: batch-culturing and inoculating the domesticated and enriched microorganisms onto the anode. Batch culture enriches the target microbial strain to ensure sufficient biomass for subsequent reactor inoculation. The domestication and enrichment culture conditions can be the optimal screening conditions described above.

[0035] In some embodiments of the present invention, the thickness of the microbial film inoculated on the surface of the anode is 0.1-3 cm. It is understood that after the microorganisms are inoculated on the surface of the anode, they may disperse on or near the anode due to their activity.

[0036] The method of this invention stimulates the metabolic activity of salt-tolerant microorganisms by alternating electric fields, which significantly improves the removal efficiency of pollutants in high-salt mine water by microorganisms and provides a new technical path for the biological treatment of high-salt mine water.

[0037] This invention also provides a high-salinity wastewater purification system. Figure 1 This is a schematic diagram of a high-salinity wastewater purification system according to the present invention, as shown below. Figure 1 As shown, the system includes a bioreactor and an alternating power supply 200. The bioreactor includes a reaction chamber 110 and a cathode 310 and an anode 320 adapted to be disposed in the reaction chamber. The cathode 310 and the anode 320 are electrically connected to the alternating power supply 200, respectively. Microorganisms are attached to the surface of the anode 320. The microorganisms include sulfate-reducing bacteria.

[0038] Figure 1 In the purification system shown, the cathode and anode are placed parallel to each other in the reaction chamber. The reaction chamber or bioreactor can be a closed structure, with only wires for connecting the cathode and anode passing through. The positions of the cathode and anode in the reaction chamber, as well as the distance between them, can be adjusted as needed. Figure 1 In the purification system shown, an inlet 121 is provided at the bottom or lower part of one side wall of the reaction chamber, and an outlet 131 is provided at the upper part or top of the other side wall. The cathode and anode are preferably parallel to the side wall with the inlet and the side wall with the outlet. Figure 1 In the schematic structure shown, the dimensions of the cathode and anode can be selected as needed.

[0039] In some embodiments of the present invention, the inlet of the reaction chamber may be connected to an inlet pool, and the outlet may be connected to an outlet pool.

[0040] The anode is selected from one or more of carbon cloth and carbon felt; the cathode is selected from one or more of stainless steel, titanium, copper and aluminum.

[0041] The present invention will be further described in detail below through examples. All raw materials used in the examples are commercially available.

[0042] The sulfate-reducing bacteria used in this embodiment of the invention were purchased from the China General Microbiological Culture Collection Center, catalog number 1.5016.

[0043] To screen and acclimatize microorganisms suitable for high-salt environments, the following examples and comparative examples exemplify the screening of salt-tolerant microorganisms to target salinity using gradient concentration and gradient contaminant concentration methods, including the following steps: S1. Under anaerobic conditions, sulfate-reducing bacteria are inoculated into a culture medium with a salinity of 2‰ and a sulfate concentration of 500 mg / L and cultured for 3-5 days (the initial inoculation concentration of sulfate reduction is 0.1%-0.3%) until the microorganisms grow stably (the sulfate removal rate remains stable), thus obtaining the first microorganism tolerant to 2‰ salinity. The culture medium contains the following components: 0.5 g / L K2HPO4, 1 g / L NH4Cl, 1.6 g / L Na2SO4, 0.06 g / L CaCl2, 0.06 g / L MgCl2, 5 g / L sodium acetate, 1 g / L yeast extract, and 0.3 g / L sodium citrate. S2. Inoculate the first microorganism from step S1 into a culture medium with a salinity of 5‰ and a sulfate concentration of 500 mg / L and culture for 3-5 days; then inoculate the microorganism into a culture medium with a salinity of 5‰ and a sulfate concentration of 1000 mg / L and culture for 3-5 days until the microorganism grows stably, thus obtaining a second microorganism tolerant to 5‰ salinity. S3. Inoculate the second microorganism from step S2 into a culture medium with a salinity increased to 7‰ and a sulfate concentration of 500 mg / L for acclimatization and culture for 3-5 days; then inoculate the microorganism into a culture medium with a salinity of 7‰ and a sulfate concentration of 1000 mg / L for culture for 3-5 days, and then inoculate the microorganism into a culture medium with a salinity of 7‰ and a sulfate concentration of 1500 mg / L for culture for 3-5 days until the microorganism grows stably, thus obtaining the third microorganism tolerant to 7‰ salinity; S4. Inoculate the microorganisms tolerant to 7‰ salinity into the culture medium in step S1 and continue screening. Repeat the screening steps from step S1 to step S3 3-4 times to obtain salt-tolerant microorganisms.

[0044] In the above-mentioned process of acclimatizing and enriching salt-tolerant microorganisms, the inoculation time of the microorganisms in a culture medium with higher salinity (or higher sulfate concentration) is determined by the desired microbial concentration, or by the ability of sulfate-reducing bacteria to stably metabolize sulfate. The component types of the culture medium used for inoculation remain unchanged; the component amounts are adjusted appropriately to achieve the target salinity. All culture media used for inoculation are sterilized, and the pH value of the culture medium is 6-9. The inoculation conditions include: a temperature of 20-30 ℃ and a shaking speed of 100-300 r / min.

[0045] In the following examples and comparative examples, the salt-tolerant microorganisms screened were cultured in batches under optimal screening conditions to enrich the target microbial strains and ensure sufficient biomass for reactor inoculation. The optimal screening conditions included a salinity of 7‰ and a sulfate concentration of 1500 mg / L.

[0046] Understandably, if a microorganism with higher salinity tolerance is required, the salinity of the culture medium during the domestication and enrichment process can be further increased.

[0047] Example 1 This embodiment illustrates the purification method for high-salinity wastewater of the present invention. Figure 1 The process is carried out in the high-salt wastewater purification system shown.

[0048] In this embodiment, the bioreactor is a rectangular closed reactor, which includes a reaction chamber (20 cm × 10 cm × 5 cm). An inlet is located at the lower part of one side wall of the reaction chamber, and an outlet is located at the upper part of the other side wall. An electrode pair is formed using carbon cloth (10 cm × 5 cm) as the anode and stainless steel mesh as the cathode.

[0049] The purification method includes the following steps: (1) The salt-tolerant microorganisms obtained through domestication and enrichment were inoculated onto the surface of the anode of the bioreactor (forming a biofilm 0.8-1.5 cm thick on the anode surface). The cathode and the anode inoculated with microorganisms were placed in the reaction chamber of the bioreactor. The cathode and anode were connected to the AC power supply through wires. Simulated mine water was added to the reaction chamber. The salinity of the simulated mine water was 5‰, the sulfate concentration was 1500 mg / L, and the pH value was 7.5. The ambient temperature was 25 ℃. (2) Start the bioreactor and connect the cathode and anode to the electrical circuit. The purification of high-salt wastewater by microorganisms includes a microbial adaptation stage and a microbial treatment stage. During the microbial adaptation phase, a low-frequency, low-intensity alternating electric field was applied, with the following conditions: electric field strength of 0.5 V / cm and frequency of 10 Hz. The adaptation and metabolic activity of the microorganisms were monitored, and the operation lasted for 10 days. Monitoring of cell membrane permeability, enzyme activity, biomembrane structure, and tolerance revealed an approximately 20% increase in cell membrane permeability, a 15% increase in enzyme activity, and a higher porosity in the biomembrane structure. The survival rate of the microorganisms in the high-salt environment increased to over 90%.

[0050] After the microorganisms adapt to the stimulation of the alternating electric field, the frequency and intensity of the alternating electric field are gradually increased. The alternating electric field conditions during the microbial treatment stage include: electric field strength of 3 V / cm and frequency of 40 Hz.

[0051] The sulfate concentration in the effluent was monitored at the end of the microbial adaptation phase and 7 days after the treatment phase, and the sulfate removal rate was calculated. The results are shown in Table 1.

[0052] Example 2 The method for purifying high-salinity wastewater in this embodiment is similar to that in Embodiment 1, except that: The alternating electric field conditions during the microbial treatment stage include: an electric field strength of 0.8 V / cm and a frequency of 40 Hz.

[0053] The sulfate concentration in the effluent was monitored at the end of the microbial adaptation phase and 7 days after the treatment phase, and the sulfate removal rate was calculated. The results are shown in Table 1.

[0054] Example 3 The method for purifying high-salinity wastewater in this embodiment is similar to that in Embodiment 1, except that: The alternating electric field conditions during the microbial treatment stage include: an electric field strength of 1 V / cm and a frequency of 40 Hz.

[0055] The sulfate concentration in the effluent was monitored at the end of the microbial adaptation phase and 7 days after the treatment phase, and the sulfate removal rate was calculated. The results are shown in Table 1.

[0056] Example 4 The method for purifying high-salinity wastewater in this embodiment is similar to that in Embodiment 1, except that: The alternating electric field conditions during the microbial treatment stage include: an electric field strength of 5 V / cm and a frequency of 40 Hz.

[0057] The sulfate concentration in the effluent was monitored at the end of the microbial adaptation phase and 7 days after the treatment phase, and the sulfate removal rate was calculated. The results are shown in Table 1.

[0058] Example 5 The method for purifying high-salinity wastewater in this embodiment is similar to that in Embodiment 1, except that: The alternating electric field conditions during the microbial treatment stage include: an electric field strength of 5.5 V / cm and a frequency of 40 Hz.

[0059] The sulfate concentration in the effluent was monitored at the end of the microbial adaptation phase and 7 days after the treatment phase, and the sulfate removal rate was calculated. The results are shown in Table 1.

[0060] Example 6 The method for purifying high-salinity wastewater in this embodiment is similar to that in Embodiment 1, except that: The alternating electric field conditions during the microbial treatment stage include: an electric field strength of 3 V / cm and a frequency of 20 Hz.

[0061] The sulfate concentration in the effluent was monitored at the end of the microbial adaptation phase and 7 days after the treatment phase, and the sulfate removal rate was calculated. The results are shown in Table 1.

[0062] Example 7 The method for purifying high-salinity wastewater in this embodiment is similar to that in Embodiment 1, except that: The alternating electric field conditions during the microbial treatment stage include: an electric field strength of 3 V / cm and a frequency of 50 Hz.

[0063] The sulfate concentration in the effluent was monitored at the end of the microbial adaptation phase and 7 days after the treatment phase, and the sulfate removal rate was calculated. The results are shown in Table 1.

[0064] Example 8 The method for purifying high-salinity wastewater in this embodiment is similar to that in Embodiment 1, except that: The alternating electric field conditions during the microbial treatment stage include: an electric field strength of 3 V / cm and a frequency of 15 Hz.

[0065] The sulfate concentration in the effluent was monitored at the end of the microbial adaptation phase and 7 days after the treatment phase, and the sulfate removal rate was calculated. The results are shown in Table 1.

[0066] Example 9 The method for purifying high-salinity wastewater in this embodiment is similar to that in Embodiment 1, except that: The alternating electric field conditions during the microbial treatment stage include: an electric field strength of 3 V / cm and a frequency of 60 Hz.

[0067] The sulfate concentration in the effluent was monitored at the end of the microbial adaptation phase and 7 days after the treatment phase, and the sulfate removal rate was calculated. The results are shown in Table 1.

[0068] Example 10 The method for purifying high-salinity wastewater in this embodiment is similar to that in Embodiment 1, except that: The alternating electric field conditions during the microbial adaptation phase include: an electric field strength of 1 V / cm and a frequency of 10 Hz.

[0069] The sulfate concentration in the effluent was monitored at the end of the microbial adaptation phase and 7 days after the treatment phase, and the sulfate removal rate was calculated. The results are shown in Table 1.

[0070] Example 11 The method for purifying high-salinity wastewater in this embodiment is similar to that in Embodiment 1, except that: The alternating electric field conditions during the microbial adaptation phase include: an electric field strength of 0.1 V / cm and a frequency of 20 Hz.

[0071] The sulfate concentration in the effluent was monitored at the end of the microbial adaptation phase and 7 days after the treatment phase, and the sulfate removal rate was calculated. The results are shown in Table 1.

[0072] Example 12 The method for purifying high-salinity wastewater in this embodiment is similar to that in Embodiment 1, except that: The simulated mine water had a salinity of 5‰, a sulfate concentration of 1000 mg / L, and a pH of 7.5. The sulfate concentration in the effluent was monitored at the end of the microbial adaptation phase and 7 days after the treatment phase, and the sulfate removal rate was calculated. The results are shown in Table 1.

[0073] Example 13 The method for purifying high-salinity wastewater in this embodiment is similar to that in Embodiment 1, except that: The simulated mine water had a salinity of 7‰, a sulfate concentration of 1500 mg / L, and a pH of 7.5. The sulfate concentration in the effluent was monitored at the end of the microbial adaptation phase and 7 days after the treatment phase, and the sulfate removal rate was calculated. The results are shown in Table 1.

[0074] Example 14 The method for purifying high-salinity wastewater in this embodiment is similar to that in Embodiment 1, except that: The alternating electric field conditions remain unchanged during the microbial treatment stage. The alternating electric field is applied in a pulsed manner, with power applied for 15 minutes and power off for 5 minutes.

[0075] The sulfate concentration in the effluent was monitored at the end of the microbial adaptation phase and 7 days after the treatment phase, and the sulfate removal rate was calculated. The results are shown in Table 1.

[0076] Example 15 The method for purifying high-salinity wastewater in this embodiment is similar to that in Embodiment 13, except that: During the microbial treatment stage, the energizing time when applying an alternating electric field in a pulsed manner is 10 minutes, and the power-off time is 3 minutes.

[0077] The sulfate concentration in the effluent was monitored at the end of the microbial adaptation phase and 7 days after the treatment phase, and the sulfate removal rate was calculated. The results are shown in Table 1.

[0078] Comparative Example 1 The method for purifying high-salinity wastewater in this comparative example is similar to that in Example 1, except that: The cathode and anode are respectively connected to a DC power supply via wires; During the microbial purification process simulating mine water, the applied voltage was 0.6 V. After 24 days of operation, the sulfate concentration in the effluent was monitored, and the sulfate removal rate was calculated. The results are shown in Table 1.

[0079] Comparative Example 2 The method for purifying high-salinity wastewater in this comparative example is similar to that in Comparative Example 1, except that: A pulsed DC power supply was applied to both the cathode and anode for 15 minutes, followed by a 5-minute power-off period. After 24 days of operation, the sulfate concentration in the effluent was monitored, and the sulfate removal rate was calculated. The results are shown in Table 1.

[0080] Table 1

[0081] The results in the table above show that the purification method provided by this invention can significantly improve the removal rate of sulfate in the effluent. Specifically, compared with applying a DC power supply in Comparative Example 1, applying an alternating electric field can significantly improve the removal rate of sulfate pollutants in the simulated mine water.

[0082] In Examples 14-15, the removal effect of sulfate was also very impressive by applying a pulsed alternating electric field during the microbial treatment stage.

[0083] Example 16 This embodiment illustrates the purification method for high-salinity wastewater of the present invention.

[0084] In this embodiment, the bioreactor is a rectangular closed reactor, which includes a reaction chamber (20 cm × 10 cm × 5 cm). An inlet is located at the lower part of one side wall of the reaction chamber, and an outlet is located at the upper part of the other side wall. An electrode pair is formed using porous carbon fiber felt as the anode (10 cm × 5 cm) and stainless steel mesh as the cathode.

[0085] The purification method includes the following steps: (1) The salt-tolerant microorganisms obtained through domestication and enrichment were inoculated onto the surface of the anode of the bioreactor (forming a biofilm 0.8-1.5 cm thick on the anode surface). The cathode and the anode inoculated with microorganisms were placed in the reaction chamber of the bioreactor. The cathode and anode were connected to the AC power supply through wires. A mine water sample was added to the reaction chamber. The salinity of the mine water sample was 3‰, the sulfate concentration was 2000 mg / L, the ammonia nitrogen concentration was 50 mg / L, and the pH value was 8. The ambient temperature was 30 ℃. (2) Start the bioreactor and connect the cathode and anode to the electrical circuit. The purification of high-salt wastewater by microorganisms includes a microbial adaptation stage and a microbial treatment stage. During the microbial adaptation phase, a low-frequency, low-intensity alternating electric field was applied. The electric field conditions included: an electric field strength of 0.5 V / cm and a frequency of 10 Hz. The adaptation and metabolic activity of the microorganisms were monitored. The operation time was 10 days. The sulfate and ammonia nitrogen concentrations in the mine water samples were measured, and the sulfate removal rate and ammonia nitrogen removal rate were calculated. After the microorganisms adapt to the stimulation of the alternating electric field, the frequency and intensity of the alternating electric field are gradually increased. The alternating electric field conditions during the microbial treatment stage include: electric field strength of 3 V / cm and frequency of 40 Hz.

[0086] After 10 days of operation during the treatment phase, the concentrations of sulfate and ammonia nitrogen in the effluent were monitored, and the sulfate removal rate and ammonia nitrogen removal rate were calculated. The results are shown in Table 2.

[0087] Example 17 The method for purifying high-salinity wastewater in this embodiment is similar to that in Embodiment 16, except that: The alternating electric field conditions remain unchanged during the microbial treatment stage. The alternating electric field is applied in a pulsed manner, with power applied for 15 minutes and power off for 5 minutes.

[0088] After 10 days of operation during the treatment phase, the concentrations of sulfate and ammonia nitrogen in the effluent were monitored, and the sulfate removal rate and ammonia nitrogen removal rate were calculated. The results are shown in Table 2.

[0089] Table 2

[0090] The data in the table above shows that by inoculating salt-tolerant microorganisms obtained through domestication and enrichment into the anode treatment of actual high-salt mine water, even when treating actual high-salt mine water, the treatment efficiency of microorganisms on high-salt wastewater can be improved by applying an alternating electric field to stimulate microbial metabolism.

[0091] It should be noted that, in order to ensure the reproduction of microorganisms, an external carbon source is added to the simulated mine water or actual mine water samples mentioned above. Generally, it is a liquid carbon source such as sodium acetate, or it can be a slow-release solid carbon source such as straw. The adjustment can be made as needed, which will not be elaborated here.

[0092] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0093] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0094] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for purifying high-salinity wastewater, characterized in that, The purification method includes: A saline solution to be treated is added to the reaction chamber of a bioreactor, and the cathode and anode of the bioreactor are placed in the saline solution; the anode is inoculated with microorganisms. The bioreactor is started, and an alternating electric field is applied to the cathode and the anode to purify the saline solution; The microorganisms include sulfate-reducing bacteria; The salinity of the salt-containing solution is 2‰-8‰; the inorganic salts in the salt-containing solution include sulfates.

2. The purification method according to claim 1, wherein, The purification process includes a microbial adaptation phase and a microbial treatment phase performed sequentially. The alternating electric field conditions during the microbial adaptation phase include: an electric field strength of 0.1-1 V / cm, a frequency of 5-20 Hz, and an operating time of 10-20 days. The alternating electric field conditions during the microbial treatment stage include: an electric field strength of 1-5 V / cm and a frequency of 20-50 Hz.

3. The purification method according to claim 2, wherein, The alternating electric field applied during the microbial treatment stage is pulsed, with an energizing time of 10-20 minutes and a pulse duty cycle of 30%-80%.

4. The purification method according to claim 1, wherein, The concentration of sulfate in the saline solution is 500-2000 mg / L.

5. The purification method according to claim 1, wherein, The salt solution also contains NH4. + The ammonia nitrogen concentration is 20-100 mg / L.

6. The purification method according to claim 1, wherein, The bioreactor uses intermittent water inlet; The ambient temperature in the reaction chamber is 20-40 ℃, preferably 15-30 ℃; the pH value of the salt solution is 6-9.

7. The purification method according to claim 1, wherein, The microorganisms were obtained through screening, domestication, and enrichment using a method including the following steps: S1. The microorganism is inoculated into a culture medium containing a first salinity and a first sulfate concentration for cultivation and domestication to obtain the first microorganism; the first salinity is 2‰-4‰ and the first sulfate concentration is 500-800 mg / L; S2. The first microorganism is inoculated into a culture medium containing a second salinity and a first sulfate concentration for cultivation and acclimatization. After the microorganism grows stably, it is inoculated into a culture medium containing a second salinity and a second sulfate concentration for cultivation and acclimatization to obtain a second microorganism; the second salinity is 5‰-6‰ and the second sulfate concentration is 900-1200 mg / L. S3. The second microorganism is inoculated into a culture medium containing a third salinity and a first sulfate concentration for cultivation and acclimatization. Then, the microorganism is inoculated into a culture medium with an increasing concentration gradient of third salinity and sulfate until the sulfate concentration is increased to the third sulfate concentration to obtain the third microorganism. The third salinity is 7‰-8‰ and the third sulfate concentration is 1500-2000 mg / L. S4. The third microorganism is inoculated into the culture medium in step S1 for domestication, and then steps S2-S3 are performed sequentially, repeating 3-4 times. Preferably, the method further includes: inoculating the domesticated and enriched microorganisms in batches and then inoculating them onto the anode.

8. The purification method according to claim 1, wherein, The thickness of the microbial film inoculated on the surface of the anode is 0.1-3 cm.

9. A high-salinity wastewater purification system, characterized in that, The system includes a bioreactor and an alternating power supply. The bioreactor includes a reaction chamber and a cathode and an anode adapted to be disposed in the reaction chamber. The cathode and the anode are electrically connected to the alternating power supply, respectively. Microorganisms, including sulfate-reducing bacteria, are attached to the surface of the anode.

10. The high-salinity wastewater purification system according to claim 9, wherein, The reaction chamber is provided with an inlet at the bottom or lower part and an outlet at the top or upper part. Optionally, the inlet is connected to an inlet pool, and the outlet is connected to an outlet pool; Optionally, the anode is selected from one or more of carbon cloth and carbon felt; the cathode is selected from one or more of stainless steel, titanium, copper and aluminum.

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