Percolate low-energy-consumption desalting process based on PSP-MIL-53

Abstract

The invention belongs to the technical field of environmental engineering and membrane separation, and discloses a percolate low-energy-consumption desalting process based on PSP-MIL-53. According to the process, a metabolic coupling symbiotic system is constructed in an immobilized reactor by adopting a pH responsive material PSP-MIL-53 and domesticated autotrophic denitrifying flora, NH4 < + > is adsorbed by the material under an acidic condition and is released as required under an alkaline microenvironment, and the release rate is driven by denitrification alkali production to be dynamically matched with microbial metabolism. By adopting the technical scheme, high-efficiency denitrification can be realized under the near-zero aeration condition without an external carbon source, and the material is excellent in cycling stability. Through deep coupling and metabolic synergy of a material-microorganism interface, inherent contradictions in the aspects of efficiency, stability and energy consumption in the prior art are successfully overcome.

Description

Technical Field

[0001] This invention belongs to the field of environmental engineering and membrane separation technology, and relates to a low-energy desalination process for leachate based on PSP-MIL-53. Background Technology

[0002] Landfill leachate, as a complex organic wastewater with extremely high pollutant concentrations, has always been a key focus and challenge in the field of environmental engineering. With the continuous increase in the amount of municipal solid waste and the extension of landfill operation years, the accumulation of inorganic salts (especially ammonia nitrogen in the form of ammonium salts) in leachate has become increasingly prominent. This not only significantly inhibits the activity of subsequent biological treatment units, but also poses a serious scaling and pollution risk to advanced treatment processes such as membrane separation.

[0003] In the existing technological system, the removal of high-concentration ammonia nitrogen mainly relies on two pathways: physicochemical adsorption and traditional biological denitrification processes. The former often uses activated carbon, zeolite, or some metal-organic framework materials to capture ammonia nitrogen, and its advantages are simple operation and rapid response; the latter converts ammonia nitrogen into nitrogen gas through the metabolic activities of nitrifying-denitrifying microbial communities, which has the advantages of thorough treatment and no secondary pollution.

[0004] However, the adsorbent material is effective against ionic ammonium ions (NH4). + The adsorption capacity and selectivity of adsorbents are constrained by factors such as solution pH, competition among coexisting ions, and the regeneration stability of the material. The adsorption process is essentially only a phase transfer of pollutants and does not achieve the mineralization or detoxification of nitrogen. If the saturated material lacks efficient and low-cost regeneration methods, it will instead create a new burden for solid waste disposal.

[0005] While traditional biological denitrification can achieve complete nitrogen conversion, its reliance on the slow proliferation of autotrophic nitrifying bacteria results in long system start-up periods, weak resistance to shock loads, and easy inactivation in leachate environments with high salinity and low carbon-to-nitrogen ratios. To maintain sufficient biomass, additional carbon sources or complex process combinations are often required. Summary of the Invention

[0006] To achieve the aforementioned objectives, this invention provides a low-energy desalination process for landfill leachate based on PSP-MIL-53. This process involves constructing a functionalized metal-organic framework material, PSP-MIL-53, with pH-responsive ammonia nitrogen release characteristics, and forming a spatially ordered, metabolically coupled symbiotic system with a specific domesticated autotrophic denitrifying bacterial community within an immobilized bioreactor. This allows for the efficient, stable, and low-energy removal of high-concentration ammonium salts from landfill leachate without the need for external carbon sources or high-energy aeration.

[0007] The PSP-MIL-53 material is prepared by introducing benzenesulfonic acid groups (PSP) through post-synthetic modification based on the classic MIL-53(Al) framework. The specific preparation method includes: dispersing the MIL-53(Al) precursor in anhydrous dimethylformamide solvent, adding p-aminobenzenesulfonic acid and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride under nitrogen protection, and reacting at 80℃ for 24 hours; after the reaction, centrifuging, washing, and vacuum drying are performed to obtain the target product PSP-MIL-53. This material retains the rhombic channel characteristics of MIL-53 in its crystal structure, and its BET specific surface area is higher than 1200 m². 2 / g, with a pore size distribution concentrated in the range of 0.8 to 1.2 nm. The key lies in the introduction of PSP, which imparts strong Brønsted acidic sites to the material, resulting in high protonation at pH values ​​below 6.0 and strong resistance to NH4+. + It exhibits strong electrostatic adsorption; when the ambient pH rises above 7.5, the sulfonate groups deprotonate, causing reversible breathing expansion of the material framework, increasing the pore size, and simultaneously enhancing electrostatic repulsion, thus promoting the adsorption of NH4+. + Desorption and release at a controlled rate.

[0008] The autotrophic denitrifying bacterial community was selectively enriched and screened from sludge in the aerobic-anoxic interface zone of a long-running landfill leachate treatment system. Its core functional strains are a mixed community of *Thiobacillus* and *Paracococcus denitrifyingus*, with a volume ratio of 3:1. This community was acclimatized for 30 generations in an inorganic culture medium with sodium thiosulfate as the electron donor, nitrate as the electron acceptor, and an initial pH of 7.8. It exhibits the ability to maintain stable denitrification activity under extreme conditions of a C / N ratio below 0.5 and a salinity above 15 g / L. Its metabolic characteristics include the ability to utilize reduced sulfur compounds as an energy source to gradually reduce nitrates or nitrites to nitrogen gas, while simultaneously consuming protons, leading to a continuous increase in the pH of the microenvironment.

[0009] The main body of the process system of this invention is an upflow anaerobic sludge bed-immobilized packing composite reactor (UASB-IFR), which has a water distribution zone, a sludge suspension zone, an immobilized packing zone, and a three-phase separation zone arranged sequentially from bottom to top. The immobilized packing zone is filled with composite microspheres made of polyvinyl alcohol-sodium alginate blended gel encapsulating PSP-MIL-53 particles and the autotrophic denitrifying bacteria. The preparation method of the composite microspheres is as follows: PSP-MIL-53 powder is mixed with an autotrophic denitrifying bacteria suspension in the logarithmic growth phase at a mass-to-volume ratio of 1g:5mL, and then mixed with 8% polyvinyl alcohol solution and 2% sodium alginate solution at a volume ratio of 3:1. The mixture is then dropped into a crosslinking bath containing 3% boric acid and 0.1mol / L calcium chloride to solidify and form composite microspheres with a particle size of 3 to 5mm. Inside the microsphere, PSP-MIL-53 particles are uniformly dispersed, and the bacteria are effectively fixed in the pores of the gel network. The distance between the two is controlled within the range of 50 to 200 μm to ensure efficient material transfer.

[0010] The process flow of this invention specifically includes the following steps:

[0011] Step 1, Pretreatment: The leachate to be treated is first homogenized through a screen and equalization tank, then enters the chemical precipitation unit, where calcium hydroxide and sodium carbonate are added to adjust the pH to 10.5, causing some calcium, magnesium ions, and phosphates to precipitate. After solid-liquid separation in the sedimentation tank, the supernatant enters the next unit. This step aims to reduce the risk of scaling in subsequent treatment units and adjust the influent pH to an alkaline range conducive to ammonia nitrogen stripping. However, this invention does not perform stripping; instead, ammonia nitrogen is retained in the liquid phase.

[0012] Step 2, Acidification Adsorption: The pretreated leachate flows into a closed acidification adsorption tower filled with unloaded PSP-MIL-53 granules. The influent pH is precisely controlled to 5.5 ± 0.2 via an online pH meter and an automatic acid pump. Under these acidic conditions, PSP-MIL-53 effectively adsorbs NH4+. + The adsorption capacity reached its maximum, with a measured value exceeding 85 mg / g. The leachate residence time in the tower was 45 minutes, and the flow rate was 0.5 m / h, ensuring an ammonia nitrogen removal rate of over 90%. After adsorption saturation, the PSP-MIL-53 was carried by the water flow into the next reactor.

[0013] Step 3, Co-conversion: Adsorption of high concentrations of NH4 +The PSP-MIL-53, along with the leachate, enters the bottom distribution zone of the UASB-IFR reactor. The initial operating conditions within the reactor are set as follows: temperature 30±1℃, hydraulic retention time 24 hours, and upflow velocity 0.8 m / h. In the sludge suspension zone at the bottom of the reactor, a small number of facultative heterotrophic bacteria exist, which can convert easily degradable organic matter remaining in the leachate into nitrite, providing initial electron acceptors for the autotrophic bacteria in the upper layer. When the water flows upward to the immobilized packing zone, NH4+ adsorbed by the PSP-MIL-53... + The autotrophic denitrifying bacteria community begins to emerge. At this time, because the leachate itself is weakly alkaline (pH approximately 7.8), the PSP-MIL-53 skeleton undergoes respiratory expansion, and NH4+... + It begins to release slowly. The released NH4... + Instead of being directly utilized, under conditions of extremely low dissolved oxygen (<0.2 mg / L), it is first oxidized to nitrite (NO2) by a small amount of ammonia-oxidizing archaea (AOA) attached to the surface of the immobilized microspheres by a small amount of these archaea. - This process consumes alkalinity, but at a relatively slow rate. The key synergistic mechanism lies in the autotrophic denitrifying bacteria below utilizing sodium thiosulfate to reduce NO2. - During the process, for every 1 mol of NO2 reduced - It will consume 1 mol H + This caused the local pH value of the microspheres to rise above 8.2. This pH increase signal was sensed by PSP-MIL-53, triggering it to accelerate the release of NH4+. + ; released NH4 + It is then oxidized to NO2 by AOA. - The latter is then consumed by denitrifying bacteria, forming a positive feedback loop. This loop causes NH4 to... + The release rate and the metabolic rate of microorganisms are precisely matched dynamically, avoiding the inhibitory effect caused by excessively high local ammonia nitrogen concentration.

[0014] Step 4, Sulfur Source Replenishment and Regeneration: To maintain the continuous activity of autotrophic denitrifying bacteria, electron donors need to be replenished to the reactor influent periodically. This invention uses sodium thiosulfate (Na2S2O3·5H2O) as the sulfur source. The dosage is calculated based on the total amount of nitrate nitrogen and nitrite nitrogen in the influent, with a molar ratio of S2O3... 2-The ratio of nitrogen to phosphorus (N) is 1.2:1. Sodium thiosulfate is gradually oxidized to sulfate in the reactor. Some sulfate ions combine with calcium ions in the leachate to form gypsum precipitate, which can be removed by periodic sludge removal. It is worth noting that PSP-MIL-53 exhibits good stability of its sulfonic acid groups after multiple adsorption-release cycles, with an adsorption capacity decay rate of less than 5% after 100 cycles. When the ammonia nitrogen concentration in the effluent exceeds 5 mg / L for three consecutive days, the material is considered partially deactivated. At this point, the regeneration process is initiated: the feed water is stopped, a dilute hydrochloric acid solution with a pH of 2.0 is injected into the reactor, and the reactor is circulated and cleaned for 2 hours to remove residual NH4+. + Complete desorption was performed; then the mixture was rinsed with deionized water until neutral, and then injected with a solution containing 0.1 g / L p-aminobenzenesulfonic acid. The mixture was statically soaked at 30°C for 12 hours to repair any sulfonic acid groups that may have detached, thus completing the material regeneration.

[0015] Step 5, Solid-Liquid Separation and Effluent: The reacted mixture enters the three-phase separation zone, where gases (mainly N2), treated effluent, and a small amount of sludge are separated. The effluent, after monitoring and meeting standards, is either discharged or sent to subsequent advanced treatment units. The generated nitrogen is collected through a top gas collection hood and can be used for system agitation or energy recovery.

[0016] In a preferred embodiment of the present invention, the immobilized packing zone of the UASB-IFR reactor is divided into upper and lower functional layers. The upper packing microspheres contain PSP-MIL-53 at a mass ratio of 2:1 to bacterial cells, focusing on rapid ammonia nitrogen capture and initial conversion; the lower packing microspheres contain this ratio of 1:2, focusing on denitrification metabolism and pH regulation. A perforated partition is provided between the two layers, allowing free passage of liquid and gas but restricting packing mixing. This layered design further optimizes the spatial matching of adsorption-conversion.

[0017] In another preferred embodiment of the present invention, a buffer tank is added between the acidification adsorption tower and the UASB-IFR reactor. This tank is used to temporarily store the leachate that has completed adsorption, ensuring continuous operation of the upstream treatment during material regeneration or maintenance of the UASB-IFR reactor. The pH in the tank is maintained at 5.5 to prevent NH4+ ions from entering. + Premature desorption.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] 1. By utilizing the pH-responsive respiration effect of the PSP-MIL-53 material, intelligent regulation of ammonia nitrogen adsorption and release is achieved, fundamentally solving the problem of adsorption-conversion kinetic mismatch in traditional symbiotic systems. The material efficiently captures NH4 under acidic conditions. + It releases OH- on demand in an alkaline microenvironment, with the release rate determined by the OH- produced by microbial metabolic activity. -Concentration is adjusted in real time to form an adaptive closed-loop control.

[0020] 2. A nitrogen salt mineralization pathway centered on autotrophic denitrification was constructed, requiring no external organic carbon source throughout the process, significantly reducing operating costs and the risk of secondary pollution. Simultaneously, the denitrification process generates alkali, raising the local pH level and cleverly providing a driving force for the release of ammonia nitrogen from PSP-MIL-53, thus achieving internal recycling of energy and materials.

[0021] 3. The overall energy consumption of the system is significantly reduced. Compared with the high-intensity aeration required by the traditional nitrification-denitrification process (the air-to-water ratio is usually greater than 20:1), the present invention only needs to maintain a low-speed circulation in the upflow reactor, and the aeration requirement is almost zero.

[0022] 4. PSP-MIL-53 material exhibits excellent regeneration stability and anti-interference capabilities. It is effective even in environments containing high concentrations of Ca. 2+ Mg 2 + Na + In the leachate matrix of humic acid, its effect on NH4 + Selective adsorption coefficient (relative to Na) + The viscosity is as high as 15, effectively avoiding competitive interference from coexisting ions. The material maintains stable performance after hundreds of cycles and has a long service life.

[0023] 5. High degree of process system integration and simple operation. Through modular design, functional units such as adsorption, conversion, and regeneration are organically combined, making it easy to achieve automated control and suitable for leachate treatment projects of different scales.

[0024] 6. By deeply coupling and metabolic synergy at the material-microbe interface, the inherent contradictions in efficiency, stability and energy consumption of existing technologies have been successfully overcome. Detailed Implementation

[0025] This invention provides a low-energy desalination process for landfill leachate based on PSP-MIL-53. The core of this process lies in constructing a functionalized metal-organic framework material, PSP-MIL-53, with pH-responsive ammonia nitrogen release characteristics. This material is then integrated with a specific, domesticated autotrophic denitrifying bacterial community within an immobilized bioreactor to form a spatially ordered, metabolically coupled symbiotic system. This allows for efficient, stable, and low-energy removal of high-concentration ammonium salts from landfill leachate without the need for external carbon sources or high-energy aeration. The following detailed description, using specific embodiments, will elaborate on the technical solution of this invention from the perspectives of material preparation, bacterial community domestication, reactor construction, process flow, and operating parameters.

[0026] The technical solution of the present invention will be described in detail below with reference to specific embodiments and comparative examples, so as to ensure that those skilled in the art can fully understand and implement the present invention.

[0027] Example 1: Acidification adsorption pH 5.5; autotrophic denitrifying bacteria spp. Thiobacillus: Paracoccus denitrifying = 3:1; PSP-MIL-53 to bacterial mass ratio in the upper and lower layers of the immobilized packing zone was 2:1 and 1:2 respectively; hydraulic retention time was 24 hours; sodium thiosulfate addition molar ratio was 1.2:1;

[0028] Preparation process: leachate pretreatment → acidification adsorption → synergistic conversion in composite reactor → sulfur source replenishment → three-phase separation → effluent.

[0029] Example 2: Acidification adsorption at pH 5.3, with the remaining formulation and process the same as in Example 1;

[0030] Preparation process: Same as in Example 1.

[0031] Example 3: Acidification adsorption at pH 5.7, with the remaining formulation and process the same as in Example 1;

[0032] Preparation process: Same as in Example 1.

[0033] Example 4: Autotrophic denitrifying bacteria serotype: paranitrogenous bacteria = 2:1, the rest of the formula and process are the same as in Example 1;

[0034] Preparation process: Same as in Example 1.

[0035] Example 5: Autotrophic denitrifying bacteria spp. Thiobacillus: Paracoccus denitrifying = 4:1, the rest of the formula and process are the same as in Example 1;

[0036] Preparation process: Same as in Example 1.

[0037] Example 6: The immobilized packing zone is a single layer (PSP-MIL-53 to bacterial cell mass ratio 1:1), and the rest of the formulation and process are the same as in Example 1;

[0038] Preparation process: Same as in Example 1.

[0039] Example 7: Hydraulic retention time 20 hours, other formulations and processes are the same as in Example 1;

[0040] Preparation process: Same as in Example 1.

[0041] Example 8: Influent ammonia nitrogen concentration 2000 mg / L, other formulations and processes are the same as in Example 1;

[0042] Preparation process: Same as in Example 1.

[0043] Comparative Example 1: Without PSP-MIL-53 material and autotrophic bacteria, traditional nitrification-denitrification was used (with added carbon source glucose, and an aeration-to-water ratio of 20:1); the other treatment objects were the same as in Example 1.

[0044] Preparation process: leachate pretreatment → aeration nitrification → anoxic denitrification → sedimentation effluent.

[0045] Comparative Example 2: No autotrophic denitrifying bacteria, only PSP-MIL-53 adsorption-regeneration cycle; the rest of the formulation and process are the same as in Example 1;

[0046] Preparation process: leachate pretreatment → acidification and adsorption → material regeneration → effluent.

[0047] Test method:

[0048] Desalination efficiency test: Detect the ammonia nitrogen concentration in the influent and effluent, calculate the removal rate; monitor the consumption of sodium thiosulfate and the amount of nitrogen generated.

[0049] Energy consumption and stability testing: Statistical analysis of electricity consumption per ton of water; recording of the number of cycles of PSP-MIL-53 and the rate of adsorption capacity decay; evaluation of the duration of bacterial community activity retention.

[0050] Process performance testing: Detect indicators such as pH and salinity of the effluent; verify long-term operational stability under conditions without external carbon source.

[0051] The test data comparisons are shown in Table 1 and Table 2.

[0052] Table 1 Comparison of Ammonia Nitrogen Removal Rate, Electricity Consumption per Ton of Water, and External Carbon Source Requirement

[0053]

[0054] Table 2 Comparison of material decay rate and bacterial activity retention time after 100 cycles

[0055]

[0056] Examples 1-8 show ammonia nitrogen removal rates ≥91% and power consumption per ton of water ≤0.78kWh, which are far superior to the comparative examples. Comparative example 1 has high energy consumption and requires an external carbon source, while comparative example 2 has a low removal rate and rapid material decay, confirming that the coupling system is the key to low-energy and high-efficiency desalination.

[0057] The increased proportion of Thiobacillus (Examples 4→1→5) improves denitrification efficiency and reduces energy consumption; the adsorption pH is within the range of 5.3-5.7, and the material adsorption-release kinetics are stable; the layered packing design (Example 1) is superior to the single-layer design (Example 6), which is more conducive to kinetic matching.

[0058] The embodiment saves more than 60% energy compared to the traditional process, requires no external carbon source, and reduces operating costs; the PSP-MIL-53 has a decay rate of ≤5% after 100 cycles of use, and the bacterial activity is maintained for more than 150 days, making it suitable for long-term operation.

[0059] The process described in this example is suitable for leachate with high nitrogen load, produces effluent that meets standards, is easy to regenerate materials, has low energy consumption and is environmentally friendly, and solves the core problems of high energy consumption and the need for carbon sources in traditional processes.

[0060] The process described in this invention achieves low-energy and high-efficiency desalination of leachate through metabolic coupling between PSP-MIL-53 and autotrophic denitrifying bacteria. Different parameter combinations can meet the treatment requirements and are suitable for high-salt and high-nitrogen wastewater treatment scenarios such as landfill leachate.

[0061] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A low-energy desalination process for leachate based on PSP-MIL-53, characterized in that, Includes the following steps: S10: Pre-treat the landfill leachate by adjusting the pH to 10.5 through chemical precipitation, removing some calcium, magnesium and phosphate, and retaining ammonia nitrogen in the liquid phase; S20: The pretreated leachate is passed into an acidification adsorption tower filled with PSP-MIL-53 particles, and the pH of the influent is controlled at 5.5, so that the PSP-MIL-53 particles can efficiently adsorb NH4 under acidic conditions. + ; S30: The adsorption-saturated PSP-MIL-53 particles are introduced into an upflow anaerobic sludge bed-immobilized packing composite reactor along with the leachate. This reactor contains, from bottom to top, a water distribution zone, a sludge suspension zone, an immobilized packing zone, and a three-phase separation zone. The immobilized packing zone is filled with composite microspheres consisting of PSP-MIL-53 particles and autotrophic denitrifying bacteria encapsulated in a polyvinyl alcohol-sodium alginate blended gel. Inside the reactor, the leachate provides a weakly alkaline environment, promoting the respiratory expansion of the PSP-MIL-53 particles and the release of NH4+. + The released NH4 + The ammonia-oxidizing archaea attached to the surface of the microspheres oxidize the nitrite, while autotrophic denitrifying bacteria use sodium thiosulfate to reduce the nitrite to generate nitrogen gas and produce OH-. - The increase in local pH further accelerates NH4+. + Release, forming a positive feedback loop of dynamic matching; S40: Sodium thiosulfate is added to the system as an electron donor according to the nitrogen load of the influent water, and a regeneration procedure is performed when the material performance deteriorates. S50: After the reaction, the mixture enters the three-phase separation zone to achieve gas, liquid and solid separation, and the effluent meets the discharge standards.

2. The low-energy desalination process for leachate based on PSP-MIL-53 according to claim 1, characterized in that, The PSP-MIL-53 particles were synthesized by introducing PSP into the MIL-53(Al) framework through post-synthesis modification. They exhibited good resistance to NH4+ at pH < 6.

0. + It exhibits strong adsorption and can controllably release NH4 due to skeletal respiratory expansion at pH > 7.

5. + .

3. The low-energy desalination process for leachate based on PSP-MIL-53 according to claim 1 or 2, characterized in that, The autotrophic denitrifying bacteria are a mixed group of Thiobacillus and Paracoccus denitrifyingus in a volume ratio of 3:

1. After 30 generations of domestication, they can stably carry out denitrification metabolism under conditions where the C / N ratio is less than 0.5 and the salinity is higher than 15 g / L.

4. The low-energy desalination process for leachate based on PSP-MIL-53 according to claim 1, characterized in that, The composite microspheres are formed by mixing PSP-MIL-53 powder and autotrophic denitrifying bacteria suspension at a mass-volume ratio of 1g:5mL, then mixing them with 8% polyvinyl alcohol solution and 2% sodium alginate solution at a volume ratio of 3:1, and finally curing them by dropping them into a crosslinking bath containing 3% boric acid and 0.1mol / L calcium chloride.

5. The low-energy desalination process for leachate based on PSP-MIL-53 according to claim 1, characterized in that, The immobilized packing zone of the upflow anaerobic sludge bed-immobilized packing composite reactor is divided into upper and lower functional layers. The mass ratio of PSP-MIL-53 to bacteria in the microspheres of the upper packing layer is 2:1, and that of the lower layer is 1:

2. A perforated partition is provided between the two layers.

6. The low-energy desalination process for leachate based on PSP-MIL-53 according to claim 5, characterized in that, The perforated partition is 5mm thick, with a pore diameter of 10mm and an opening rate of 20%, allowing liquids and gases to pass through but restricting the mixing of the packing material.

7. The low-energy desalination process for leachate based on PSP-MIL-53 according to claim 1, characterized in that, A buffer tank is provided between the acidification adsorption tower and the upflow anaerobic sludge bed-immobilized packing composite reactor to temporarily store the leachate that has completed adsorption. The pH in the tank is maintained at 5.5±0.

1.

8. The low-energy desalination process for leachate based on PSP-MIL-53 according to claim 1, characterized in that, The molar ratio of sodium thiosulfate added to S2O3 2- The ratio of N to 1.2 is 1, and the injection point is located at the outlet of the equalization tank.

9. The low-energy desalination process for leachate based on PSP-MIL-53 according to claim 1, characterized in that, The regeneration process includes: after stopping the water intake, injecting dilute hydrochloric acid with a pH of 2.0 for circulating cleaning, then rinsing with deionized water until neutral, and finally injecting a buffer solution containing 0.1 g / L p-aminobenzenesulfonic acid for static soaking to repair sulfonic acid groups.

10. The low-energy desalination process for leachate based on PSP-MIL-53 according to claim 1, characterized in that, The three-phase separation zone has a built-in inclined plate sedimentation module made of polypropylene.

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