High-salinity wastewater treatment method and system combined with salt-tolerant strain

Abstract

The invention relates to the technical field of wastewater treatment, and discloses a high-salinity wastewater treatment method and system combined with a salt-tolerant strain. The invention discloses a high-salinity wastewater treatment method combined with a salt-tolerant strain. The method comprises the following steps: biodegradation treatment: biodegrading organic pollutants in wastewater by using the salt-tolerant strain; adsorption treatment: feeding the wastewater into an adsorption reactor, and adding an adsorbent to adsorb dissolved salt in the wastewater; ion exchange treatment: feeding the treated wastewater into an ion exchange column, and realizing effective exchange removal of sodium ions, calcium ions and magnesium ions by using a combination of strong acid type resin and strong alkali type resin; and evaporative crystallization: further concentrating and crystallizing to obtain recoverable salt. The high-salinity wastewater treatment method and system combined with the salt-tolerant strain can be widely applied to high-salinity industrial wastewater, such as the fields of petroleum, chemical engineering, metallurgy, electric power and the like and the scenes of seawater desalination of concentrated water and the like, and technical support is provided for realizing environmental protection, energy conservation, emission reduction and resource utilization.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, and in particular to a high-salt wastewater treatment method and system combined with salt-tolerant bacteria. Background Art

[0002] With the acceleration of industrialization, a large amount of high-salinity wastewater is discharged into water bodies, causing serious water environmental problems. High-salinity wastewater usually contains the following main characteristics: ① High salt content: Common dissolved salts include NaCl, CaCl2, MgCl2, Na2SO4 and other anions and cations, and the salinity can often reach 5% or even higher; ② High concentration of organic pollutants: This type of wastewater is often accompanied by high COD (chemical oxygen demand) and BOD (biochemical oxygen demand); ③ A variety of toxic substances: In the production process of chemical, metallurgical, electric power, petroleum and other industries, wastewater may contain various heavy metals, difficult-to-degrade organic matter, volatile organic compounds (VOC) and other environmental persistent pollutants (POPs).

[0003] Traditional treatment technologies such as simple reverse osmosis (RO) and evaporative crystallization often face high operating costs and treatment difficulties in practical applications due to high energy consumption, large equipment investment, and poor adaptability to high-salt and high-organic wastewater. In recent years, the ability of salt-tolerant microorganisms to maintain normal growth and continuously degrade organic matter in a high-salt environment has attracted attention, and the corresponding biological treatment of high-salt wastewater research has continued to deepen. At the same time, the mature application of adsorption materials and ion exchange resins in removing dissolved ions has also provided the possibility for further purification of high-salt wastewater.

[0004] Therefore, how to rationally combine salt-tolerant bacterial strain biodegradation, adsorption treatment, ion exchange and evaporation crystallization in the same process flow to achieve the synergistic removal of organic matter and salt in high-salt wastewater and achieve significant improvements in economy, stability and treatment depth has become a key technical issue that needs to be urgently resolved in the current industry. Summary of the invention

[0005] The purpose of the present invention is to provide a high-salinity wastewater treatment method and system combined with salt-tolerant bacteria, which can be widely used in high-salinity industrial wastewater, such as in the fields of petroleum, chemical industry, metallurgy, electric power, and other fields, as well as seawater desalination concentrated water and other scenarios, to provide technical support for achieving green environmental protection, energy conservation and emission reduction, and resource utilization.

[0006] To achieve the above object, the present invention provides a method for treating high-salt wastewater in combination with a salt-tolerant strain, comprising the following steps: Step 1, biodegradation treatment: Use salt-tolerant strains to biodegrade organic pollutants in wastewater; adjust the wastewater, then inoculate the salt-tolerant strains, maintain dissolved oxygen at 2-6 mg / L or in an anaerobic state, and the salt-tolerant strains convert organic matter in the wastewater into carbon dioxide, water and intermediate products; Step 2, adsorption treatment: the wastewater is sent to the adsorption reactor, and adsorbent is added to adsorb the dissolved salts in the wastewater; this process further reduces the ion content in the water, creating good conditions for subsequent ion exchange; Step 3, ion exchange treatment: The treated wastewater is sent to an ion exchange column, and a combination of strong acid and strong base resins is used to achieve effective exchange and removal of sodium ions, calcium ions, and magnesium ions; Step 4, evaporation and crystallization: Use an evaporation device to further concentrate and crystallize the recoverable salt.

[0007] Furthermore, the salt-tolerant strain in step 1 is of the genus Halomonas, and the Halomonas strain is adapted to high-salt wastewater by distributed domestication before biodegradation treatment. The domestication time is 3-7 days, and the conditions for biodegradation treatment are: NaCl concentration of 5%-10%, inoculation amount of 5%-10%, temperature of 20°C-40°C, pH of 6.5-8.5. After biodegradation treatment, the salinity in the wastewater is reduced to 3-8%.

[0008] Furthermore, the mechanism of biodegradation in step 1 is as follows: Halomonas salt-tolerant strains synthesize osmotic protective substances or adjust ion channels in cells to adapt to high-salt environments, and use organic matter as a carbon source, and ultimately convert the carbon source into CO2, H2O or other intermediates through aerobic or anaerobic metabolic pathways, thereby significantly reducing the COD and BOD of the wastewater.

[0009] Furthermore, in step 2, the adsorbent is one or a combination of zeolite, bentonite, activated carbon, the particle size of the adsorbent is 0.5-5 mm, the adsorption temperature is 10-50° C., the adsorption time is 1-6 h, and the amount of the adsorbent is 5% to 15% of the wastewater volume.

[0010] Furthermore, in step 3, the resin exchange capacity is 10-30 meq / g, and the treatment time of the ion exchange reaction is 30-180 minutes.

[0011] Furthermore, in step 3, the inner diameter of the ion exchange column is 5 cm-30 cm, the column height is 50 cm-150 cm, the flow rate of the wastewater is 0.5-3 BV / h, and the dissolved salt concentration in the wastewater is reduced to below 1% after ion exchange treatment.

[0012] Furthermore, in step 4, the temperature of the evaporation device is controlled at 70° C.-120° C., the evaporation reaction time is 6-24 hours, and the NaCl content in the recovered crystalline salt is greater than 80%.

[0013] The present invention also provides a system for implementing the above-mentioned high-salt wastewater treatment method combined with salt-tolerant bacteria, comprising: Bioreactor: It is equipped with an immobilized carrier or suspension culture system of Halomonas salt-tolerant strains, with a volume of 10 L-100 L, a temperature control system, a pH monitoring and adjustment system, and a stirring or aeration device to maintain the conditions of 20-40°C and pH 6.5-8.5; Adsorption reactor: used to remove dissolved salts from wastewater, the adsorption reactor is filled with adsorbent; Ion exchange column: used for ion exchange reaction, filled with strong acid and strong base ion exchange resin; Evaporation device: used to evaporate the salt in the crystallized wastewater, equipped with an automatic control system to recover the crystallized salt and achieve zero liquid discharge.

[0014] Furthermore, the adsorption reactor adopts a dynamic bed or fixed bed mode, and is equipped with a water inlet and outlet, flow control and a regular backwashing system to extend the service life of the adsorbent, and can select batch or continuous operation mode according to demand; after adsorption saturation, the adsorbent can be regenerated with acid, alkali or salt solution.

[0015] Furthermore, the ion exchange column is generally arranged in series or parallel, the resin bed adopts a multi-layer filling structure, and includes liquid level monitoring, pressure monitoring and flow rate control devices to ensure the ion exchange efficiency. It can also be connected to a resin regeneration device to regenerate the exchanged resin through acid-base regeneration liquid and recycle it to ensure the convenience of resin regeneration.

[0016] Furthermore, the evaporation device adopts a single-effect or multi-effect evaporator, and can also be equipped with a vacuum system to reduce the boiling point and thus reduce energy consumption. It includes functional units such as a heater, an evaporation chamber, a condenser, and a crystallizer; it is equipped with an automatic control system that can adjust the operating pressure, temperature, and feed flow in real time. The recovered salt can enter further washing and drying processes to obtain industrial-grade or higher-purity salt products.

[0017] The advantages and positive effects of the high-salt wastewater treatment method and system combined with salt-tolerant bacteria described in the present invention are: 1. The present invention provides an efficient high-salinity wastewater treatment method, and specifically discloses the culture medium formula, inoculation amount, salt concentration and temperature of Halomonas salt-tolerant strains under 5% to 10% salinity conditions. The strain can biodegrade organic pollutants in high-salinity wastewater under anaerobic or aerobic conditions; by optimizing environmental conditions such as temperature (20°C to 40°C), pH value (6.5 to 8.5), and dissolved oxygen (2 to 6 mg / L), microorganisms can quickly degrade organic matter in wastewater and significantly reduce COD and BOD. The dissolved salts are removed by combining adsorbents (zeolite, bentonite, activated carbon) adsorption and strong acid and strong base ion exchange resins, and salt recovery is achieved by evaporation and crystallization to achieve the goal of zero liquid discharge (ZLD). The method can be widely used in high-salinity industrial wastewater, such as petroleum, chemical, metallurgy, electric power and other fields, as well as seawater desalination concentrated water and other scenes, providing technical support for achieving green environmental protection, energy conservation and emission reduction, and resource utilization.

[0018] 2. The present invention provides an efficient high-salt wastewater treatment system, including a bioreactor, an adsorption reactor, an ion exchange column and an evaporation device. The system utilizes the strong biodegradation ability of the salt-tolerant Halomonas strain in a 5% to 10% high-salt environment and its high adaptability to salt, so that the system operates stably, has low energy consumption and high treatment efficiency.

[0019] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of a high-salt wastewater treatment system combined with a salt-tolerant strain in an embodiment of the present invention.

[0021] Reference numerals 1. Wastewater tank; 2. Bioreactor; 3. Attached reactor; 4. Ion exchange column; 5. Evaporation device. DETAILED DESCRIPTION

[0022] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0023] Unless otherwise defined, technical or scientific terms used in the present invention shall have the common meanings understood by one having ordinary skills in the field to which the present invention belongs.

[0024] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention. The experimental methods without specific conditions in the following examples are usually measured in accordance with national standards. The experimental instruments, equipment and reagents without source indication in the following examples are all commercially available raw materials.

[0025] Unless otherwise defined or indicated, all professional and scientific terms used in the present invention have the same meanings as those familiar to those skilled in the art. In addition, any methods and materials similar or equivalent to those described herein can be applied to the present invention.

[0026] The salt-tolerant strain of the genus Halomonas is Halomonas salina, strain number: DSM 5928.

[0027] A high-salinity wastewater treatment system combined with a salt-tolerant bacterial strain, comprising: Bioreactor 2: It is equipped with a culture system of Halomonas salt-tolerant strains, with a volume of 10 L-100 L, equipped with a temperature control system, a pH monitoring and adjustment system, and a stirring or aeration device to maintain the conditions of 20-40°C and pH 6.5-8.5. Wastewater is pumped into the bioreactor from the wastewater tank.

[0028] Adsorption reactor 3: used to remove dissolved salts in wastewater, the adsorption reactor is filled with adsorbent; Ion exchange column 4: used for ion exchange reaction, filled with strong acid and strong base ion exchange resins; Evaporation device 5: used to evaporate the salt in the crystallized wastewater, equipped with an automatic control system to recover the crystallized salt and achieve zero liquid discharge.

[0029] The wastewater treatment process is as follows: ① The wastewater is pumped from the wastewater tank 1 into the bioreactor 2, where the wastewater reacts with the salt-tolerant strains. After biodegradation treatment, the salinity of the wastewater is reduced to 3-8%. The wastewater is then pumped into the adsorption reactor 3 to remove dissolved salts in the wastewater. The wastewater is then pumped into the ion exchange column 4, where the concentration of dissolved salts in the wastewater is reduced to less than 1% after ion exchange treatment. Finally, the salt in the wastewater is evaporated and crystallized by the evaporation device 5, and the NaCl content in the recovered crystallized salt is greater than 80%.

[0030] 1. Process flow and system design of the present invention: 1. The processing process of the present invention is as follows: The first step is raw water conditioning: high-salt wastewater enters the comprehensive regulating tank to adjust the pH to neutral, the temperature to an appropriate range, and remove large impurities or suspended particles; The second step is biodegradation: biodegradation is carried out under the action of salt-tolerant bacteria, and COD and BOD are greatly reduced; The third step is adsorption: after conditioning, it enters the adsorption unit to remove some salt and residual macromolecular organic matter; Step 4, ion exchange: continue to remove dissolved salts in depth to reduce ion concentration; The fifth step is the evaporation device: the salt is recovered by concentration and crystallization to form a solid salt product at the end, achieving zero liquid discharge.

[0031] 2. Cultivation method of salt-tolerant strains of Halomonas genus: (1) Culture medium formula and cultivation conditions: 50-100 g / L (corresponding to 5%-10% salinity wastewater) NaCl; 10 g / L peptone; 5 g / L yeast extract; 2 g / L KCl; 2 g / L MgSO4·7H2O; 0.5 g / L KH2PO4; pH value is 7.0 (±0.2); inoculum size is 5%-10% (v / v); culture temperature is 20℃-40℃, usually around 30℃.

[0032] (2) The acclimatization strategy is as follows: the strain is first cultured under 5% NaCl conditions for 24 to 48 hours, and then gradually increased to 7%, 8%, and 10%; each salinity gradient must ensure the stable growth of the strain and maintain a high COD degradation capacity.

[0033] (3) Analysis of biodegradation mechanism: At the cellular level, Halomonas strains can eliminate excess Na by accumulating osmotic protectants (such as betaine, glutamate, etc.) or ion pumps. + To maintain the osmotic pressure balance inside and outside the cells; under aerobic conditions, the strain oxidizes organic matter into CO2 and H2O; under anaerobic conditions, intermediate products (such as acetic acid, ethanol, methane, etc.) may be produced, but COD and BOD can still be greatly reduced.

[0034] 3. Design and operation of bioreactor: (1) Reactor form: It can be a completely mixed stirred reactor, sequencing batch bioreactor (SBR) or membrane bioreactor (MBR), etc., which is determined based on the actual production scale and wastewater properties.

[0035] (2) Salt-tolerant strains: Halomonas bacteria are selected, which have an optimal salinity tolerance range of 5% to 15% and can grow normally under high osmotic pressure. Laboratory acclimatization and cultivation are required in advance to allow the bacterial flora to adapt to the organic matrix type and salt concentration in the wastewater.

[0036] (3) Operating parameters: temperature is 20-40℃; pH is in the range of 6.5-8.5; oxygen supply requirements, maintaining dissolved oxygen (DO) at around 2-6 mg / L (for aerobic strains), or maintaining a low oxygen or anaerobic environment in anaerobic systems; hydraulic retention time (HRT) is usually controlled at 12-72 hours, depending on the organic load.

[0037] 4. Design and operation of adsorption reactor: (1) Adsorbent types: ① Zeolite: has strong adsorption capacity for divalent cations such as calcium and magnesium; ② Activated carbon: has a rich pore structure and can adsorb organic matter and some ions at the same time; ③ Bentonite: also has a certain removal effect on heavy metals or polar organic matter.

[0038] (2) Operation mode: ① Static batch adsorption: contact in a stirred container for a certain period of time, and then solid-liquid separation; ② Dynamic column adsorption: wastewater continuously passes through the adsorption filler layer, and regeneration or replacement is carried out after adsorption saturation.

[0039] (3) Key parameters: temperature is controlled at 10-50 °C; adsorbent dosage is 5%-15% of the wastewater volume; contact time is 1-6 hours; after adsorption saturation, acid, alkali or salt solution can be used for regeneration, depending on the type and economic feasibility of the adsorbent.

[0040] 5. Design and operation of ion exchange columns: (1) Resin type: Strong acid resin (such as Dowex 50W×8): suitable for cations (Na + , Ca 2+ Mg 2+ Strong base resin (such as Amberlite IRA900): suitable for anion (Cl - 、SO4 2- Weakly acidic or weakly alkaline resins can also be selected and combined according to the main ion components of the wastewater to be treated to save chemical agents.

[0041] (2) Operating conditions: The flow rate is controlled at 0.5-3 BV / h (based on the resin volume); the exchange capacity is 10-30 meq / g; the operating temperature is room temperature or moderate heating (20-50°C); the regeneration method is that strong acid resins are usually regenerated with HCl or other acid solutions, and strong base resins can be regenerated with NaOH solution; the operating mode is divided into co-current regeneration or countercurrent regeneration to improve resin utilization and regeneration efficiency.

[0042] 6. Design and operation of evaporation crystallization unit: ① The evaporation method is atmospheric pressure evaporation or vacuum evaporation. Vacuum evaporation can significantly reduce the boiling point of water and save heating energy; ② Multi-effect evaporation: Use multi-stage flash evaporation or steam series to recover heat and further reduce total energy consumption. ③ The temperature range is controlled at 70-120°C, and the evaporation time is 6-24 hours, depending on the processing volume and the type of evaporator. ④ Salt recovery: The crystals produced by evaporation and crystallization can obtain high-purity NaCl or other crystalline salts through centrifugation, drying and screening. For wastewater containing multiple salts, it can be recovered step by step or selectively according to the solubility and crystallization characteristics of the salt system. ⑤ Condensate reuse: The condensed water produced during the evaporation process can be recycled back to the biological system or used as industrial water to achieve the recycling of water resources.

[0043] 2. Experimental methods and reaction mechanism analysis: 1. Experimental methods: Halomonas strains were inoculated into synthetic wastewater containing 5% to 10% NaCl or actual high-salt wastewater, and the COD and BOD reduction rates were measured after 24 to 48 hours. The adsorption and ion exchange processes were tested for Na + , Ca 2+ Mg 2+ Plasma removal rate; the concentrated liquid is evaporated and crystallized in a small evaporator, and the salt recovery rate and energy consumption are measured.

[0044] 1.1 Biodegradation experiment: The domesticated salt-tolerant strains are inoculated into simulated or actual high-salt wastewater containing 5% to 10% salt. Appropriate temperature and pH are maintained, and COD and BOD are tested regularly. The experimental group is compared with the control group (uninoculated strains or inoculated with non-salt-tolerant strains) to evaluate the degradation efficiency of the salt-tolerant strains.

[0045] The specific experimental design is as follows: Experimental group: The Halomonas salt-tolerant strain, which had been acclimated for 3 to 7 days, was used with an inoculation amount of 5% to 10%. Biodegradation treatment was carried out under 5% to 10% NaCl conditions for 48 hours.

[0046] Control group: no strain was inoculated or common strain that was not acclimated to salt tolerance was inoculated and treated under the same conditions.

[0047] Degradation efficiency (with COD and BOD as indicators): Experimental Group: The initial COD is about 800 mg / L, which can be reduced to about 200 mg / L after 48 hours of treatment, and the degradation efficiency is about 75%.

[0048] The initial BOD was about 600 mg / L, which dropped to about 120 mg / L after treatment, and the degradation efficiency was about 80%.

[0049] Control group: COD only dropped to about 600 mg / L, and the degradation efficiency was about 25%.

[0050] BOD dropped to about 450 mg / L, and the degradation efficiency was about 25%.

[0051] Due to different experimental environments and conditions, the above degradation efficiencies vary.

[0052] 1.2 Adsorption experiment: Different adsorption materials (zeolite, activated carbon, bentonite, etc.) were compared; the effects of adsorbent dosage, contact time, salt concentration and other factors on the removal rate of salt and organic matter were investigated; the Na + , Ca 2+ Mg 2+ The concentration of ions was used to evaluate the removal effect.

[0053] 1.3 Ion exchange experiment: The exchange effects of different types of resins on target ions were compared under the same test conditions (same flow rate, same contact time); the ion exchange capacity and removal rate were calculated by analyzing the concentration of ions in the water before and after treatment; the resin was regenerated multiple times to assess its service life and regeneration efficiency.

[0054] 1.4 Evaporation crystallization experiment: Take the wastewater after ion exchange and place it in a vacuum evaporator or a normal pressure evaporator for evaporation; record the temperature, evaporation rate, condensation amount and crystallization yield, and determine the composition and purity of the salt in the solid phase; calculate the comprehensive energy consumption and economic feasibility of the system based on the energy consumption and salt production.

[0055] 2. Industrial verification: A pilot test was conducted in a 10 L to 100 L bioreactor to examine the COD degradation efficiency as salinity, temperature, and pH changed. The system then entered a combined adsorption to ion exchange and evaporation crystallization system to verify the treatment effect and stability.

[0056] 3. Chemical reaction and physicochemical mechanism: 3.1 Biodegradation process: In a high-salt environment, Halomonas strains maintain normal metabolism by regulating intracellular osmotic pressure and membrane ion channels; during the logarithmic growth period, microorganisms grow vigorously, quickly decompose organic pollutants, and reduce COD and BOD; under aerobic conditions, O2 is used as an electron acceptor, and intermediate fermentation products may be produced under anaerobic conditions. This biochemical process greatly reduces the evaporation and processing energy consumption of subsequent processes. The chemical reaction process under aerobic conditions is: C6H 12 O6+6O2→6CO2+6H2O; anaerobic conditions may produce intermediates such as ethanol and methane; salt-tolerant strains can continue to grow and degrade pollutants under high osmotic pressure environments through physiological mechanisms such as regulating intracellular osmotic pressure and synthesizing osmotic protective substances.

[0057] 3.2 Adsorption process: Adsorption of Na by zeolite + For example: Zeolite-(M + )+Na + ⇋Zeolite-Na + +M + ; Where M⁺ represents the original metal ions in the zeolite. The actual process includes multiple mechanisms such as physical adsorption (van der Waals force) and ion exchange (chemical adsorption).

[0058] 3.3 Ion exchange process: Examples of strong acid resins exchanging sodium and calcium ions: R-H+Na + →R-Na+H + ; 2R-Na + Ca 2+ →R2Ca+2Na + ; 3.4 Evaporation crystallization process: The high-salt solution begins to evaporate at a certain temperature, and the salinity continues to concentrate. After reaching supersaturation, crystal nuclei are formed and grow into crystals; the final precipitated crystals can be separated from the solid and liquid by centrifugation or filtration.

[0059] 3. Comprehensive removal effect and energy consumption analysis: 3.1 Removal efficiency: COD and BOD are removed by 60% to 80% in the bioreactor respectively, and adsorption and subsequent processes can remove another 15% to 30%, so that the final effluent meets all standards; the salt is removed by multiple stages of adsorption, ion exchange and evaporation and crystallization, with a removal rate of more than 95%, and zero liquid discharge can be achieved.

[0060] 3.2 Energy consumption analysis: Compared with simple multi-effect evaporation, front-end biological treatment, adsorption and ion exchange reduce the salt content that needs to be evaporated, thereby reducing the evaporation load; by optimizing the design of each unit and multi-effect evaporation, energy consumption can be significantly saved (reducing evaporation heat consumption by approximately 20% to 40%).

[0061] 3.3 Recovery value: The salt obtained by crystallization can be recycled as industrial salt to a certain extent; wastewater mixed with multiple salts can be crystallized step by step to recover different proportions of NaCl, sulfate, calcium chloride, etc.

[0062] The following is a specific explanation using the high-salt wastewater from MCC Changtian Chemical Plant and the wastewater from Anyang Iron and Steel Plant as examples.

[0063] Example 1 Water quality and operating conditions: high-salt wastewater from MCC Changtian Chemical Plant, with a salt concentration of 5% and a COD of about 800 mg / L; Bioreactor: salt-tolerant strain Halomonas genus, aerobic conditions, HRT of 48 h, temperature of 30 °C, pH about 7.5; Adsorption: Batch method, add zeolite 5% (volume ratio), stir and adsorb for 3 h; Ion exchange: Use strong acid and strong base resins in series, with an exchange capacity of 15-25 meq / g and a flow rate of 1.5 BV / h; Evaporation crystallization: atmospheric pressure evaporator, temperature 90℃, evaporation time 12 h.

[0064] Treatment effect: COD of bioreactor effluent dropped to 200 mg / L; salt concentration dropped to 2% after adsorption; salt concentration further dropped to 0.5% after ion exchange; evaporation and crystallization achieved zero liquid discharge, and the purity of recovered salt NaCl was about 80%.

[0065] Example 2 Water quality and operating conditions: Anyang Iron and Steel Plant wastewater, salt concentration 10%, COD 1500 mg / L; Bioreactor: anaerobic-aerobic combination, salt-tolerant strain Halomonas genus, batch operation, cycle 48 h, temperature 35°C; Adsorption: activated carbon 10% (volume ratio), dynamic column adsorption, flow rate 0.8 BV / h, temperature 25°C; Ion exchange: strong acid resin Dowex 50W×8, flow rate 2 BV / h, operating temperature 30℃; Evaporation device: vacuum multiple-effect evaporation, operating temperature 70-80℃, evaporation time 10 h.

[0066] Treatment effect: COD dropped to below 500 mg / L after biodegradation; salt concentration dropped from 10% to 5% after adsorption; residual salt concentration dropped to 2% after ion exchange; vacuum evaporation achieved zero liquid discharge and recovered about 85% of salt.

[0067] The high-salt wastewater treatment method combined with the salt-tolerant bacteria of the present invention has the following excellent effects: (1) Halomonas salt-tolerant strains have strong biodegradation ability in high-salinity wastewater.

[0068] Through reasonable culture medium formulation, inoculation amount, temperature and pH optimization, the biodegradation ability of Halomonas salt-tolerant strains under 5% to 10% salinity conditions was significantly improved. The strains can metabolize efficiently in high-salt environments and reduce COD and BOD concentrations.

[0069] (2) Multi-level process collaboration.

[0070] The present invention adopts a multi-stage process of biodegradation → adsorption → ion exchange → evaporation and crystallization to coordinate, and the multi-stage treatment significantly improves the removal efficiency of organic matter and inorganic salts; ultimately, zero liquid discharge (ZLD) can be achieved, and high-purity salt can be recovered for resource utilization.

[0071] (3) Energy conservation, emission reduction and universality.

[0072] Compared with single multi-effect evaporation or reverse osmosis, the present invention reduces energy consumption; the process flow can be modularly applied to the fields of chemical industry, metallurgy, electric power, petroleum, etc., and has strong applicability.

[0073] (4) Economic and environmental benefits.

[0074] The present invention effectively reduces the pressure of high-salt wastewater discharge on the environment; recovers salt to increase economic value, and meets the sustainable development and green production needs of enterprises.

[0075] In summary, the present invention aims at the problems of high salt content, high COD and high energy consumption of traditional processes faced by high-salt wastewater treatment, and proposes a comprehensive treatment method and system that integrates multiple technologies such as biodegradation of Halomonas salt-tolerant strains, adsorption, ion exchange and evaporation crystallization. By regulating the microbial growth conditions such as culture medium formula, inoculation amount, salinity, temperature, etc., the strain can be effectively cultivated and utilized at a salt concentration of 5% to 10%, so that it can efficiently remove organic matter in wastewater; subsequent adsorption and ion exchange are combined to reduce salt, and then evaporation and crystallization are used to recover salt, so as to achieve the goal of water resource reuse and zero liquid discharge. It has broad application prospects and significant economic and social benefits in the treatment of various types of high-salt wastewater on an industrial scale.

[0076] Therefore, the present invention adopts the above-mentioned high-salt wastewater treatment method and system combined with salt-tolerant bacteria, discloses a high-efficiency wastewater treatment method that combines salt-tolerant bacteria biological treatment technology with adsorbent adsorption method and ion exchange technology, and is supplemented by evaporation crystallization process to achieve zero liquid discharge (ZLD). The method can be widely used in the industrial treatment of high-salt wastewater, such as chemical, metallurgical, electric power, petroleum and other industries.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for treating high-salt wastewater by combining salt-tolerant bacteria, characterized in that: The following steps are involved: Step 1, biodegradation treatment: using salt-tolerant bacteria to biodegrade organic pollutants in wastewater; The wastewater is conditioned and then inoculated with salt-tolerant strains to maintain dissolved oxygen at 2-6 mg / L or in an anaerobic state. The salt-tolerant strains convert organic matter in the wastewater into carbon dioxide, water and intermediate products. Step 2, adsorption treatment: sending the wastewater into an adsorption reactor and adding an adsorbent to adsorb the dissolved salts in the wastewater; Step 3, ion exchange treatment: The treated wastewater is sent to an ion exchange column, and a combination of strong acid and strong base resins is used to achieve effective exchange and removal of sodium ions, calcium ions, and magnesium ions; Step 4, evaporation and crystallization: Use an evaporation device to further concentrate and crystallize the recoverable salt.

2. The method for treating high-salt wastewater in combination with a salt-tolerant strain according to claim 1, characterized in that: The salt-tolerant strain in step 1 is of the genus Halomonas. Before biodegradation treatment, the strain of the genus Halomonas is adapted to high-salt wastewater by distributed domestication. The domestication time is 3-7 days. The conditions for biodegradation treatment are: NaCl concentration of 5%-10%, inoculation amount of 5%-10%, temperature of 20°C-40°C, pH of 6.5-8.

5. After biodegradation treatment, the salinity in the wastewater is reduced to 3-8%.

3. A method for treating high-salt wastewater in combination with salt-tolerant bacteria according to claim 1, characterized in that: The mechanism of biodegradation in step 1 is: Halomonas salt-tolerant strains synthesize osmotic protective substances or adjust ion channels in cells to adapt to high-salt environments, and use organic matter as a carbon source, and ultimately convert the carbon source into CO2, H2O or other intermediates through aerobic or anaerobic metabolic pathways, thereby significantly reducing the COD and BOD of the wastewater.

4. The method for treating high-salt wastewater in combination with a salt-tolerant strain according to claim 1, characterized in that: In step 2, the adsorbent is one or a combination of zeolite, bentonite, activated carbon, the particle size of the adsorbent is 0.5-5mm, the adsorption temperature is 10-50°C, the adsorption time is 1-6h, and the amount of the adsorbent is 5% to 15% of the wastewater volume.

5. The method for treating high-salt wastewater in combination with a salt-tolerant strain according to claim 1, characterized in that: In step 3, the resin exchange capacity is 10-30 meq / g, and the treatment time of the ion exchange reaction is 30-180 minutes.

6. The method for treating high-salt wastewater in combination with a salt-tolerant strain according to claim 1, characterized in that: In step 3, the inner diameter of the ion exchange column is 5 cm-30 cm, the column height is 50 cm-150 cm, the flow rate of the wastewater is 0.5-3 BV / h, and the dissolved salt concentration in the wastewater is reduced to less than 1% after ion exchange treatment.

7. The method for treating high-salt wastewater in combination with a salt-tolerant strain according to claim 1, characterized in that: In step 4, the temperature of the evaporation device is controlled at 70° C.-120° C., the evaporation reaction time is 6-24 hours, and the NaCl content in the recovered crystalline salt is greater than 80%.

8. A system for implementing a high-salt wastewater treatment method in combination with a salt-tolerant strain as described in any one of claims 1 to 7, characterized in that: include: Bioreactor: It is equipped with a culture system of Halomonas salt-tolerant strains, with a volume of 10 L-100 L, a temperature control system, a pH monitoring and adjustment system, and a stirring or aeration device to maintain the conditions of 20-40°C and pH 6.5-8.5; Adsorption reactor: used to remove dissolved salts from wastewater, the adsorption reactor is filled with adsorbent; Ion exchange column: used for ion exchange reaction, filled with strong acid and strong base ion exchange resin; Evaporation device: used to evaporate the salt in the crystallized wastewater, equipped with an automatic control system to recover the crystallized salt and achieve zero liquid discharge.

9. The system according to claim 8, characterized in that: The adsorption reactor adopts a dynamic bed or a fixed bed mode, and is equipped with a flow control and a regular backwashing system to extend the service life of the adsorbent; after adsorption saturation, the adsorbent can be regenerated with an acid, alkali or salt solution.

10. The system according to claim 8, characterized in that: The resin bed of the ion exchange column adopts a multi-layer filling structure and includes liquid level monitoring, pressure monitoring and flow rate control devices to ensure the ion exchange efficiency and the convenience of resin regeneration.

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