A landfill leachate membrane concentrate treatment system

Abstract

The present invention discloses a landfill leachate membrane concentrate treatment system, which comprises a pretreatment system, a biochemical system, and a deep oxidation treatment system. The pretreatment system comprises a membrane concentrate storage tank, an electrolytic reactor, an iridium-ruthenium-coated electrode assembly, a regulated DC power supply, and a treated liquid collection tank. The biochemical system includes a water distribution tank, an anaerobic membrane bioreactor, an aerobic membrane bioreactor, a nitrogen source storage tank, a carbon source storage tank, a sodium chloride storage tank and its associated dosing pump, a sludge storage tank, and a treated water storage tank. The deep oxidation treatment system comprises a Fenton reactor, an acid storage tank, an alkali storage tank, a ferrous sulfate storage tank, a hydrogen peroxide storage tank, and its associated dosing pump. This invention offers the advantages of low investment, good stability, high treatment efficiency, and convenient operation and management.

Description

Technical Field

[0001] The invention relates to landfill leachate treatment, in particular to a landfill leachate membrane concentrate treatment system. Background Art

[0002] Statistics show that my country's annual municipal solid waste production has increased from 150 million tons in 2008 to 240 million tons in 2019, with an annual growth rate of approximately 9-10%. Currently, sanitary landfill remains the primary method of treating municipal solid waste in my country (65.5% of which is landfill and 32.5% is incineration). During the sanitary landfill process, 0.2 m3 of leachate is generated for every ton of solid waste. Leachate contains high concentrations of toxic and hazardous substances such as ammonia nitrogen (NH4+-N), nitrate nitrogen (NO3--N), organic pollutants, and heavy metals. If contaminated, rivers, groundwater, and soil will pose a direct threat to human health.

[0003] Currently, the mainstream treatment process for landfill leachate utilizes a combination of biochemical methods and membrane filtration. Membrane filtration methods include nanofiltration (NF) and reverse osmosis (RO). Dilute water from membrane-treated water can be discharged if it meets standards, while concentrated water (NF and RO concentrates, typically 2-4 times the concentration of leachate) requires special treatment and disposal. Its water quality is characterized by high salinity (the salt content of reverse osmosis concentrate can reach 30-50g / L). High hardness and color (nanofiltration concentrate is brown-black); contains a variety of pollutants, including (1) high concentration of organic matter (nanofiltration concentrate COD is 3000-5000 mg / L, and it is difficult to degrade organic matter); (2) high concentration of nitrate nitrogen (nanofiltration concentrate mainly contains 200-400 mg / L ammonia nitrogen, reverse osmosis concentrate mainly contains 1000-1500 mg / L nitrate nitrogen); (3) inorganic salt ions including chloride ions (Cl-), sulfate ions (SO42-), calcium ions (Ca2+), etc.; (4) heavy metal ions (As , Cd, Cr, Co, Cu, Ni, Pb, Zn, etc.); (5) Soluble organic pollutants (DOM) mainly include humic acid (HA), fulvic acid (FA), hydrophilic organic compounds (Hyl), etc.; aromatic compounds, halogenated hydrocarbon compounds, etc. Heavy metal ions such as Zn, Fe, Mg, Cr, etc. in membrane concentrate can complex with refractory organic matter in the membrane concentrate to form substances with high molecular weight and biological toxicity. Therefore, research on treatment technology for landfill leachate membrane concentrate has become a hot spot in the current research and development of environmental protection technology.

[0004] Physicochemical treatment technologies for landfill leachate membrane concentrate include physical methods such as re-injection, evaporation, solidification, and coagulation sedimentation, as well as advanced oxidation methods such as ozone oxidation, Fenton oxidation, electrochemical oxidation, microwave radiation, and photoelectrocatalytic oxidation. Biochemical treatment technologies include traditional activated sludge, anaerobic upflow reactors, anaerobic membrane bioreactors, aerobic membrane bioreactors, and anaerobic ammonium oxidation. In addition, combined physicochemical and biochemical treatment processes are also used, such as a combination of ozone oxidation, electrocoagulation, and biochemical treatment.

[0005] Currently, some domestic landfills use a re-injection method to spray untreated membrane concentrate back into the landfill or into the front-end collection tanks of the landfill leachate treatment system. This results in a significant accumulation of pollutants such as heavy metals and nitrates in the treatment system. Other landfills use evaporation to treat the concentrate, but this leads to high operating costs and the generation of secondary pollutants due to corrosion in the evaporation equipment and the need to meet exhaust gas standards. Because the concentrate contains biotoxic organic matter, heavy metal ions, high Cl- concentrations, and other bio-inhibiting components, biochemical treatment processes currently require a combination of physicochemical pretreatment and biochemical treatment technologies to degrade and convert the concentrate's pollutants into harmless substances.

[0006] Effective treatment methods for recalcitrant COD components in leachate membrane concentrate primarily include ozone oxidation, Fenton oxidation, and electrolysis. In practice, the ozone concentration produced by the ozone generator is limited to removing organic pollutants with unsaturated bonds, resulting in limited oxidation effectiveness. The optimal pH range for Fenton oxidation is acidic conditions of 3-5, requiring pH adjustment before and after the reaction, making the process complex. Electrolysis offers advantages as a pretreatment for the concentrate, as the concentrate contains inorganic electrolytes, eliminating the need for electrolyte addition and pH adjustment. While it can achieve moderate removal of COD, salinity, and Cl-, it also requires high electrode plate and electricity costs. Membrane bioreactors can enrich sludge containing salt-tolerant microorganisms. During the startup of the biochemical reaction system, they effectively mitigate the effects of high salinity on the breakup of sludge flocs, maintain a high concentration of degrading bacteria, and particularly favor the enrichment of slow-growing nitrifying bacteria, ensuring that nitrification activity is not inhibited by high salinity. Therefore, anaerobic and aerobic membrane bioreactors are the most suitable options. Summary of the Invention

[0007] The purpose of the present invention is to provide a landfill leachate membrane concentrate treatment system, which has the advantages of low investment, good stability, high treatment rate and convenient operation and management.

[0008] The above-mentioned object of the present invention is achieved through the following technical solutions:

[0009] A landfill leachate membrane concentrate treatment system includes a pretreatment system, a biochemical system, and a deep oxidation treatment system. The pretreatment system comprises a membrane concentrate storage tank, an electrolytic reaction tank, an iridium-ruthenium-coated electrode assembly, a regulated DC power supply, and a treated liquid collection tank. The biochemical system includes a water distribution tank, an anaerobic membrane bioreactor tank, an aerobic membrane bioreactor tank, a nitrogen source storage tank, a carbon source storage tank, a sodium chloride storage tank and its associated dosing pump, a sludge storage tank, and a treated water storage tank. The deep oxidation treatment system comprises a Fenton reaction tank, acid and alkali storage tanks, a ferrous sulfate storage tank, a hydrogen peroxide storage tank, and its associated dosing pump.

[0010] The present invention is further configured as follows: the landfill leachate membrane concentrate includes a nanofiltration concentrate and a reverse osmosis concentrate. The nanofiltration concentrate is first pre-treated in an electrolytic reactor and then fed into a water distribution tank according to a given ratio to be mixed with the reverse osmosis concentrate. The mixed liquid passes through an anaerobic membrane bioreactor and an aerobic membrane bioreactor (inoculated with pre-acclimated salt-tolerant sludge) to remove ammonia nitrogen, nitrate and COD components in the concentrate. The treated water is then deeply treated in a Fenton oxidation reactor to remove the difficult-to-biodegrade COD, thereby basically meeting the recharge water quality standards of the landfill.

[0011] The present invention is further configured as follows: in the pre-acclimation seed sludge operation stage of the treatment system: the anaerobic tank and aerobic tank sludge of the municipal landfill leachate biochemical treatment facility are used as seed sludge, an anaerobic membrane bioreactor tank, an aerobic membrane bioreactor tank, and a semi-continuous operation mode are adopted, and the raw water with a step-by-step increase in salinity (sodium chloride as the salinity component) and a total nitrogen concentration and COD concentration close to that of the concentrate (ammonia nitrogen and nitrate nitrogen as the total nitrogen components, glucose as the COD component) is used to acclimate the seed sludge to improve its salt tolerance. The operating conditions and methods are as follows:

[0012] Step S1: installing a microfiltration flat membrane assembly (membrane pore size of 2-3 microns) in the anaerobic membrane bioreactor tank and the aerobic tank of the aerobic membrane bioreactor tank, with a volume ratio of 1:2 between the anaerobic tank and the aerobic tank, a total hydraulic retention time of 5 days, a dissolved oxygen concentration of 0.2 mg / L or less in the anaerobic tank, a dissolved oxygen concentration of 2 mg / L or more in the aerobic tank, a circulation pump flow rate between the anaerobic tank and the aerobic tank of 2 times the daily water inflow (i.e., a circulation ratio of 2), and a sludge concentration of 30 g / L or less.

[0013] Step S2, tap water is added to the water distribution tank, and the daily water intake is calculated based on the hydraulic retention time of 5d. The nitrogen source storage tank is respectively dosed with ammonium sulfate (ammonia nitrogen source) and potassium nitrate (nitrate nitrogen source), the carbon source storage tank is dosed with glucose solution, and the sodium chloride storage tank is dosed with sodium chloride solution; the daily dosage of the reagent is calculated based on the daily water intake, and the concentrations of the added ammonia nitrogen and nitrate nitrogen are 400mg / L and 1000mg / L respectively, the glucose concentration is 5000mg / L, and the sodium chloride concentration ranges from 10g / L, 15g / L, 20g / L, 25g / L, 30g / L step increase; Example of calculation of reagent dosage: Assuming that the total reaction volume of the anaerobic membrane bioreactor and the aerobic membrane bioreactor is 50m3, the hydraulic retention time is 5d, and the daily water inflow is 10m3, then the dosage of ammonia nitrogen and nitrate nitrogen is 4kg and 10kg respectively, the dosage of glucose is 50kg, and the dosage of sodium chloride increases from 100kg, 150kg, 200kg, 250kg and 300kg. The operation cycle of each additional concentration gradient is 10-15 days.

[0014] Step S3, adopting an intermittent water inlet operation mode, with water inlet to the anaerobic tank and water outlet from the aerobic tank (extracted through the flat membrane), the water inlet pump (including the raw water pump, the nitrogen source dosing pump, and the glucose dosing pump) and the extraction water pump running 5 times a day, each running for 60 minutes, the daily cumulative flow rate of the raw water pump and the extracted water is set according to the total reaction volume and the 5-day hydraulic retention time, the daily cumulative flow rate of the ammonia nitrogen, nitrate dosing pump and the glucose dosing pump is set according to the daily dosage of ammonia nitrogen, nitrate and glucose, and the membrane extracted water from the aerobic tank is sent to a water storage tank for storage;

[0015] Step S4: Sampling is performed at the inlet and outlet every two days for analysis of ammonia nitrogen, total nitrogen, COD, and salinity. Sludge concentration is measured every ten days. When the sludge concentration exceeds 30 g / L, 20% of the aerobic tank sludge liquid is discharged. The sludge pre-acclimation phase is terminated when the sodium chloride concentration is increased to 30 g / L and the system effluent total nitrogen removal rate stabilizes at above 80%.

[0016] The present invention is further configured as follows: 4-1 The electrolytic pretreatment operation method of the nanofiltration membrane concentrate is as follows:

[0017] Step S1: The nanofiltration membrane concentrate is fed into an electrolytic reaction tank, and a blower is started to feed air into the bottom of the electrolytic reaction tank, so that small bubbles are formed through the porous tubes arranged at the bottom to produce a weak stirring effect;

[0018] Step S2: The positive and negative electrode plates are placed crosswise (with a spacing of 1 cm between the plates). The surface of the electrode plates is coated with an iridium-ruthenium alloy film, which has good electrical conductivity and corrosion resistance. The service life of the plates is more than 1000 hours. A regulated DC power supply is turned on, a constant current is used, the current density is set to 10 mA / cm2, and the electrolysis reaction time is 2 hours.

[0019] Step S3: Turn off the blower, manually start the infusion pump, and send the electrolytically pretreated nanofiltration membrane concentrate into the water distribution tank;

[0020] The preparation method of the mixed solution of electrolytic pretreatment nanofiltration concentrate and reverse osmosis concentrate is as follows:

[0021] The nanofiltration membrane concentrate obtained by 4-1 electrolysis pretreatment and the reverse osmosis membrane concentrate in the reverse osmosis membrane concentrate storage tank are mixed according to the ratio of the liquid level height of the electrolysis pretreatment nanofiltration membrane concentrate to the liquid level height of the reverse osmosis membrane concentrate in the water distribution tank, and the content of the two concentrates in the mixed liquid is adjusted. When the liquid level ratios are 1:2 and 1:1 respectively, the content of the electrolysis pretreatment nanofiltration concentrate and the reverse osmosis concentrate in the mixed liquid in the water distribution tank are 33% and 67%, 50% and 50% respectively.

[0022] Under the inlet conditions where the content of electrolytic pretreatment nanofiltration concentrate and reverse osmosis concentrate is 50%, when the total anaerobic and aerobic reaction volume is 50m3, the hydraulic retention time is 10d, and the daily water inlet is 5m3, 2.5m3 of electrolytic pretreatment nanofiltration membrane concentrate and 2.5m3 of reverse osmosis membrane concentrate need to be mixed. If the electrolysis device processes 0.5m3 of nanofiltration concentrate every 2h, 5 batches of nanofiltration membrane concentrate need to be electrolyzed every day, which takes about 12h to complete. The water inlet pump is operated 5 times a day, once every 4h, and 1.0m3 of water is ingested each time (including 0.5m3 of electrolytic pretreatment nanofiltration membrane concentrate). A total of 2.5m3 of electrolytic pretreatment nanofiltration concentrate can be prepared every day.

[0023] By adopting the above technical solution,.

[0024] The present invention is further configured as follows: in the start-up operation stage of the treatment system for treating the mixed solution of the nanofiltration membrane concentrate and the reverse osmosis concentrate: the mixed solution of the nanofiltration membrane concentrate and the reverse osmosis concentrate that has been pretreated by electrolysis is added to the water distribution tank, and the operation method and conditions of the anaerobic membrane bioreactor and the aerobic membrane bioreactor described in 3.1 are followed, and the hydraulic retention time is calculated as 10d. The nitrogen source storage tank is only dosed with ammonium sulfate (ammonia nitrogen source) solution, and the carbon source storage tank is dosed with glucose solution. The daily dosage of the reagent is calculated according to the daily water inflow, and the added ammonia nitrogen concentration is 200mg / L and the glucose concentration is 5000mg / L (assuming the reverse The total reaction volume of the reactor is 50m3, the hydraulic retention time is 10d, and the daily water inlet is 5m3. The dosage of ammonia nitrogen and glucose is 2kg and 50kg respectively. The nitrogen content of the electrolytic pretreatment nanofiltration concentrate and the reverse osmosis concentrate of the mixed liquid in the water distribution tank is first set to 33% and 67%. After running for 21-42 days, when the total nitrogen removal rate of the system effluent is stabilized at about 80%, it is adjusted to 50% and 50%. It continues to run until the total nitrogen removal rate of the system effluent is stabilized at about 80% again. It is considered that the anaerobic membrane bioreactor and aerobic membrane bioreactor treatment systems have entered the stable operation stage.

[0025] Sampling is done at the inlet and outlet every 2 days to analyze the concentrations of ammonia nitrogen, total nitrogen, COD and salinity. The sludge concentration is measured every 10 days. When the sludge concentration exceeds 30 g / L, 20% of the aerobic tank sludge liquid is discharged.

[0026] Operate the raw water pump, nitrogen source dosing pump, glucose dosing pump and water extraction pump according to the operation method described in 3.3; the extracted water is stored in the biochemical effluent tank.

[0027] The present invention is further configured to use a Fenton oxidation process to deeply treat the effluent from the anaerobic membrane bioreactor tank and the aerobic membrane bioreactor tank in the biochemical effluent tank, and the operation method is as follows:

[0028] The biochemical effluent in the biochemical effluent tank is sent to the Fenton reaction tank, the agitator is started to run at a low speed, the acid tank metering pump is started (to prepare 1-2 mol / L sulfuric acid solution), and the sulfuric acid solution is sent to the Fenton reaction tank at a low flow rate. When the pH meter reading gradually decreases to 3, the acid tank metering pump is stopped; the ferrous sulfate tank metering pump (1.3 mol / L ferrous sulfate heptahydrate solution) is started, and the ferrous sulfate solution is sent to the Fenton reaction tank at a low flow rate. When the ferrous sulfate concentration in the reaction tank reaches 0.022 mol / L, the ferrous sulfate tank metering pump is stopped; and the ferrous sulfate tank metering pump is started. The metering pump of the hydrogen peroxide storage tank (30% hydrogen peroxide solution) delivers hydrogen peroxide at a low flow rate to the Fenton reaction tank. When the hydrogen peroxide concentration in the reaction tank reaches 0.25 mol / L, the metering pump of the hydrogen peroxide storage tank is stopped. The timing is started, and stirring is continued until the Fenton reaction reaches 2 hours. The metering pump of the alkali solution storage tank (0.2-0.4 mol / L sodium hydroxide solution) is started to deliver the alkali solution at a low flow rate to the Fenton reaction tank. The reading of the pH meter is observed to gradually rise to about 7, and the metering pump of the alkali solution tank is stopped. The infusion pump of the Fenton reaction tank is started to deliver all the treated water in the tank to the clean water storage tank.

[0029] In summary, the beneficial technical effects of the present invention are:

[0030] The project involves a landfill leachate membrane concentrate treatment system. The system consists of a pretreatment system, a biochemical system, and a deep oxidation treatment system. The pretreatment system comprises a membrane concentrate storage tank, an electrolytic reactor, an iridium-ruthenium-coated electrode assembly, a regulated DC power supply, and a treated liquid collection tank. The biochemical system includes a water distribution tank, an anaerobic membrane bioreactor, an aerobic membrane bioreactor, nitrogen source / carbon source / sodium chloride storage tanks and their associated dosing pumps, a sludge storage tank, and a treated water storage tank. The deep oxidation treatment system comprises a Fenton reactor, acid / alkali / ferrous sulfate / hydrogen peroxide storage tanks and their associated dosing pumps. The landfill leachate membrane concentrate includes nanofiltration membrane and reverse osmosis membrane concentrate. The nanofiltration concentrate is first pre-treated with high-concentration COD and salinity through an electrolysis reaction device to reduce its biological toxicity, and then mixed with the reverse osmosis membrane concentrate in a given ratio. It passes through anaerobic membrane bioreactors and aerobic membrane bioreactors (containing pre-cultured salinity-tolerant and concentrate-inhibited acclimated sludge) to remove ammonia nitrogen, nitrate and COD components in the concentrate. The treated water is then deeply treated in a Fenton oxidation reactor to remove difficult-to-biodegrade COD and color, basically meeting the recharge water quality standards of the landfill. It has the advantages of low investment, good stability, high treatment rate, and convenient operation and management. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a process flow chart of an embodiment of the present invention;

[0032] Figure 2 The device process of an embodiment of the present invention;

[0033] Figure 3 The time changes of TN, NH4+-N and COD concentrations of the inlet and outlet water during the sodium chloride tolerant salinity pre-acclimation sludge process of the embodiment of the present invention;

[0034] Figure 4 The time variation of the concentrations of TN, NO3--N and NH4+-N in the inlet and outlet water and their removal rates during the treatment of raw water with different mixing ratios of electrolytic pretreatment nanofiltration membrane concentrate (E-NF) and reverse osmosis membrane concentrate (RO) in the salt-tolerant sludge of the embodiment of the present invention;

[0035] Figure 5 The comparison of the removal rates of NH4+-N and NO3--N by salt-tolerant acclimated sludge under different raw water conditions of electrolytic pretreatment nanofiltration membrane concentrate content in the embodiment of the present invention;

[0036] Figure 6 The time variation of the COD concentration of the inlet and outlet water and its removal rate during the process of treating raw water with different mixing ratios of electrolytic pretreatment nanofiltration membrane concentrate (E-NF) and reverse osmosis membrane concentrate (RO) in the salt-tolerant acclimated sludge of the embodiment of the present invention;

[0037] Figure 7The time variation of COD removal rate in the electrolytic pretreatment nanofiltration concentrate of an embodiment of the present invention;

[0038] Figure 8 The time variation of salinity in the electrolytic pretreatment nanofiltration concentrate of an embodiment of the present invention;

[0039] Figure 9 The effect of plate spacing and current density on COD removal rate in the electrolytic pretreatment nanofiltration concentrate of the embodiment of the present invention;

[0040] Figure 10 The effect of the molar ratio of n(H2O2) to n(Fe2+) on COD removal in the nanofiltration membrane concentrate treated by Fenton oxidation in an embodiment of the present invention is shown;

[0041] Figure 11 The effect of pH on COD removal rate in the nanofiltration membrane concentrate treated by Fenton oxidation according to an embodiment of the present invention;

[0042] Figure 12 The time variation of COD removal rate of nanofiltration concentrate, reverse osmosis concentrate and biochemical effluent treated by Fenton oxidation in an embodiment of the present invention.

[0043] Explanation of the accompanying symbols: 1. Reverse osmosis membrane concentrate storage tank; 2. Nanofiltration concentrate storage tank; 3. Electrolysis reaction tank; 4. Regulated DC power supply; 5. Water distribution tank; 6. Anaerobic reaction tank; 7. Aerobic reaction tank; 8. Flat membrane assembly; 9. Biochemical effluent storage tank; 10. Fenton reaction tank; 11. Sludge storage tank; 12. Clean water storage tank; 13. Nitrogen source storage tank; 14. Carbon source storage tank; 15. Sodium chloride storage tank; 16. Acid storage tank; 17. Alkali storage tank; 18. Ferrous sulfate reagent storage tank; 19. Hydrogen peroxide storage tank; 20. pH meter. DETAILED DESCRIPTION

[0044] Example:

[0045] like Figure 1As shown, a landfill leachate membrane concentrate treatment system adopts an electrolysis pretreatment process + anaerobic membrane bioreactor, an aerobic membrane bioreactor biochemical process + Fenton oxidation deep treatment process to construct a membrane concentrate treatment system. The leachate membrane concentrate raw liquid (mainly the nanofiltration concentrate with high pollution) is first subjected to electrolysis pretreatment (the process parameters are determined by the concentrate electrolysis experiment) to degrade the high concentration of COD and salinity in the concentrate to alleviate the toxic inhibitory effect of these components on the subsequent biological treatment system; an anaerobic membrane bioreactor, an aerobic membrane bioreactor, and a semi-connected In the continuous operation mode, the anaerobic and aerobic tank sludge of the landfill leachate treatment facility is used as the seed sludge (with a certain tolerance to the toxic substances and salinity of the concentrate). In the pre-acclimation seed sludge stage, the raw water with step-by-step salinity increase (sodium chloride as the salinity component) and the total nitrogen concentration and COD concentration close to the concentrate (ammonia nitrogen and nitrate nitrogen as the total nitrogen components, glucose as the COD component) is used to enrich the salt-tolerant nitrifying bacteria and denitrifying bacteria. When the total nitrogen removal rate of the effluent of the anaerobic membrane bioreactor and the aerobic membrane bioreactor is stable at more than 80%, the pre-acclimation operation is completed; in the membrane concentrate In the sludge acclimation stage, a mixture of electrolytically pretreated nanofiltration membrane concentrate and reverse osmosis concentrate (the nanofiltration membrane concentrate content is increased from 30% to 75%) is used as raw water, and ammonia nitrogen and glucose are used as external sludge nutrient nitrogen sources and denitrification carbon sources. When the total nitrogen removal rate of the effluent from the anaerobic membrane bioreactor and the aerobic membrane bioreactor is stabilized at more than 80%, the membrane concentrate acclimation sludge process is completed. Through data analysis, the most suitable nanofiltration membrane concentrate content of the mixed solution of nanofiltration membrane concentrate and reverse osmosis concentrate is finally determined as the design of the membrane concentrate inlet composition of the present invention. Finally, the Fenton oxidation process is used to deeply treat the effluent from the anaerobic membrane bioreactor and aerobic membrane bioreactor to further oxidize and decompose the difficult-to-biodegrade COD components. The Fenton oxidation deep treatment process parameters are determined by the concentrated liquid Fenton treatment experiment. The effluent from the anaerobic membrane bioreactor and aerobic membrane bioreactor under the best acclimation effect influent conditions (i.e., the total nitrogen concentration and COD concentration are both the lowest) is used. The Fenton oxidation treatment experiment is carried out under the best Fenton oxidation process conditions to finally obtain the effluent from the membrane concentrate treatment system of the present invention. The water quality can meet the recharge water quality standards of the landfill. The process flow constructed according to this design concept is as follows: Figure 1 As shown:

[0046] Among the key technologies employed in this invention, the principle of electrolytic pretreatment technology is to utilize electrode reactions to initially decompose high-concentration COD and salinity in the concentrate, thereby alleviating the toxic inhibitory effects of these components on subsequent biological treatment systems. The anaerobic membrane bioreactor and aerobic membrane bioreactor technologies utilize anaerobic and aerobic sludge from landfill leachate treatment facilities as seed sludge (which exhibits a certain tolerance to the toxic substances and salinity of the concentrate) to denitrify the total nitrogen components in the mixture of the electrolytically pretreated nanofiltration membrane concentrate and the reverse osmosis concentrate by aerobic nitrification and anaerobic denitrification. The Fenton oxidation process is used to deeply treat the effluent from the anaerobic membrane bioreactor and aerobic membrane bioreactor, further oxidizing and decomposing the difficult-to-biodegrade COD components to ensure that the water quality meets the recharge water quality standards for landfills. The design of the raw water treatment for each treatment system in the entire process follows the principle of proceeding from easy to difficult and gradually deepening, ultimately achieving effective treatment of the membrane concentrate.

[0047] like Figure 2 As shown in FIG. 1 , (1) the pre-acclimation operation method of the sodium chloride salinity resistant sludge in the anaerobic membrane bioreactor and the aerobic membrane bioreactor:

[0048] Open the tap water valve and inject tap water into the water distribution tank 5 to the high liquid level point of the Y4-liquid level controller;

[0049] Fresh sludge liquid taken from the anaerobic tank and aerobic tank of the landfill leachate treatment facility is directly loaded into the anaerobic reaction tank 6 and the aerobic reaction tank 7 respectively, with the sludge loading height being 1 / 2 of the reaction tank depth. The J1-agitator is started and stirred at a low speed to suspend the sludge liquid in the anaerobic reaction tank 6. At the same time, the VG-2# valve is opened and the G2-blower is started to oxygenate and stir the aerobic reaction tank 7. The V-6# valve is opened, the P-6# pump is manually started, and the Y5-liquid level controller is started to send tap water from the water distribution tank 5 into the anaerobic reaction tank 6. When the liquid level is higher than the upper end of the partition between the anaerobic reaction tank 6 and the aerobic reaction tank 7, the anaerobic sludge liquid overflows into the 7-aerobic reaction tank 7. When the liquid level reaches the high point of the Y5-liquid level controller, the controller instructs the P-6# pump to stop. Open the V-11# valve and manually start the P-11# circulation pump. Set the circulation flow rate to the sum of the reaction volumes of the anaerobic reaction tank 6 and the aerobic reaction tank 7 / d. Return the sludge liquid from the aerobic reaction tank 7 to the anaerobic reaction tank 6. At the same time, the liquid from the anaerobic reaction tank 6 overflows to the aerobic reaction tank 7. After the P-11# circulation pump has been running for 24 hours, the sodium chloride salinity resistant sludge pre-acclimation operation can be started.

[0050] Operation method of pre-acclimation of sludge with sodium chloride salinity tolerance: The purpose of pre-acclimation of sludge with sodium chloride salinity tolerance is to enrich salt-tolerant nitrifying bacteria and denitrifying bacteria. The acclimation process adopts intermittent anaerobic water inlet and intermittent aerobic water outlet. The daily water inlet is set according to the total hydraulic retention time of anaerobic / aerobic for 5 days. The flow rate of P-11# circulation pump between anaerobic and aerobic is set to 2 times of the daily water inlet (i.e. the circulation ratio is 2); tap water is injected into the 5-water distribution tank 5 to about 2 / 3 of the tank depth every day; the PLC time relay is used to control the operation of P-6# water inlet pump and P-12# suction water outlet pump. Frequency and time, use microfiltration flat membrane assembly 8 to retain sludge in 7-aerobic reaction tank 7 (the pore size of the flat membrane is about 2-3 microns), intermittent operation of P-12# suction pump is conducive to overcoming membrane resistance, the membrane assembly box is equipped with a diffuser, and the small bubbles generated by the aeration pipe rise from the gaps between the membranes to continuously remove the dirt on the membrane surface. When it is found that the dirt on the surface of a membrane is seriously accumulated, use a tool to pull out the contaminated membrane from the membrane assembly box, wipe off the dirt with a sponge and then insert it into the membrane assembly box; the daily water intake is based on the total hydraulic stop of anaerobic / aerobic The retention time is set to 5 days, and the concentration of the reaction sludge is controlled within 30g / L. The P-6# water inlet pump and the P-12# water extraction pump are started 5 times a day, each operation is 60 minutes, and the membrane filtered water extracted by P-12# is sent to the biochemical effluent storage tank 9; ammonium sulfate and potassium nitrate are respectively added to the nitrogen source storage tank 13, glucose is added to the carbon source storage tank 14, and sodium chloride is added to the sodium chloride storage tank 15; the daily dosage of the reagents is calculated according to the daily water inflow, and the concentrations of ammonia nitrogen and nitrate nitrogen added are 400mg / L and 1000mg / L respectively, and the concentration of glucose is 5000m g / L, and the sodium chloride concentration was increased in steps from 10g / L, 15g / L, 20g / L, 25g / L, and 30g / L (each increase lasting 10-15 days). The daily dosage of the reagents was calculated as follows: assuming the total anaerobic and aerobic reaction volume was 50m3, the hydraulic retention time was 5d, the daily water inflow was 10m3, the ammonia nitrogen and nitrate nitrogen dosages were 4kg and 10kg respectively, the glucose dosage was 50kg, and the sodium chloride dosages were 100kg, 150kg, 200kg, 250kg, and 300kg respectively. When the sodium chloride salinity sludge pre-acclimation began, the V7#, V8#, and V9# valves were opened, and the PLC time relay was used to control the P-7#, P-8#, and P-9# metering pumps, which were operated 5 times a day, each for 60 minutes.

[0051] Sampling and Analysis Methods: Samples were collected at the inlet and outlet every two days for analysis of ammonia nitrogen, total nitrogen, COD, and salinity concentrations. Nitrification and denitrification activity, as well as the stability of COD degradation performance, were assessed by analyzing the temporal trends of these concentrations in the inlet and outlet water. Sludge concentration was measured every ten days. When the sludge concentration exceeded 30 g / L, 20% of the aerobic sludge was discharged to reduce the sludge concentration and mitigate the impact of membrane fouling on the effluent pump operation. The sodium chloride-tolerant salinity sludge pre-acclimation process concluded when the total nitrogen removal rate in the effluent stabilized above 80% around the 15th day after the sodium chloride concentration was increased to 30 g / L.

[0052] (2) Start-up method for treating the mixed solution of nanofiltration concentrate and reverse osmosis concentrate in anaerobic membrane bioreactor and aerobic membrane bioreactor:

[0053] 2-1 Preparation method of mixed solution of nanofiltration membrane concentrate and reverse osmosis membrane concentrate:

[0054] Open the V-1# valve, manually start the P-1# pump, start the Y1-liquid level controller, and send the reverse osmosis (RO) membrane concentrate of the landfill leachate treatment equipment into the reverse osmosis membrane concentrate storage tank 1 to the Y1-liquid level control liquid level high point (the opening and closing of P-1# is controlled by the Y1-liquid level device); open the V-2# valve, manually start the P-3# pump, start the Y2-liquid level controller, and then send the nanofiltration membrane (NF) concentrate of the landfill leachate treatment facility into the 2-nanofiltration concentrate storage tank 2 to the Y2-liquid level control liquid level (high point, the start and stop of the P-2# pump is controlled by the Y2-liquid level device).

[0055] Open the V-4# valve, manually start the P-4# pump, start the Y3-liquid level controller, and send the nanofiltration membrane concentrate from the nanofiltration concentrate storage tank 2 into the electrolysis reaction tank 3 to the high point of the Y3-liquid level controller (the start and stop of the P-4# pump is controlled by the Y3-liquid level controller), and record the volume of the nanofiltration concentrate VNF filled; open the VG-1# valve to about 1 / 3-1 / 2 opening, start the G1-blower to send air into the bottom of the electrolysis reaction tank 3, and form small bubbles through the porous tubes arranged at the bottom to produce a weak stirring effect, the purpose of which is to make the liquid mix evenly during the electrode reaction process. The positive and negative electrode plates are placed crosswise (the plate spacing is 1 cm), and the electrode plate surface is coated with an iridium-ruthenium alloy film with good conductivity. To ensure the water's resistance and corrosion resistance, turn on regulated DC power supply 4, operating at a constant current density of 10 mA / cm². After 2 hours of operation, the electrolysis operation is complete. Turn off blower G1, open valve V-5#, and manually start pump P-5# to deliver the VNF electrolytic pretreated nanofiltration membrane concentrate to distribution tank 5 until the liquid level reaches HNF. Open valve V-3#, manually start pump P-3#, and activate level controller Y4 to deliver reverse osmosis membrane concentrate from reverse osmosis membrane concentrate storage tank 1 to distribution tank 5. The level controller is set to 2HNF. When the level reaches this level, the Y4 level controller instructs pump P-3# to stop. At this point, the volume of reverse osmosis membrane concentrate delivered, VRO, equals VNF. This means that the content of the electrolytic pretreated nanofiltration concentrate in distribution tank 4 is 50%, and the content of the reverse osmosis membrane concentrate is also 50%. Similarly, when the control liquid level height of the Y4-liquid level controller is set to 3HNF, the volume of the reverse osmosis membrane concentrate VRO fed in is 2VNF, that is, the content of the electrolytic pretreatment nanofiltration concentrate in the water distribution tank 5 is 33%, and the content of the reverse osmosis membrane concentrate is 67%.

[0056] 2-2 Start-up method of the mixed solution of nanofiltration concentrate and reverse osmosis concentrate:

[0057] After (1) the pre-acclimation of the sodium chloride resistant salinity sludge is completed, the liquid storage tank 5 (mixture of the nanofiltration concentrate and reverse osmosis concentrate prepared in 2-1) is stored, and the daily water inlet is set according to the total hydraulic retention time of anaerobic / aerobic is 10d, and the flow rate of the P-11# circulation pump between anaerobic and aerobic is set to 2 times the daily water inlet (i.e., the circulation ratio is 2); the PLC time relay is used to control the operating frequency and time of the P-6# water inlet pump and the P-12# suction water outlet pump. The P-6# water inlet pump is sent to the anaerobic reaction tank 6, and the reaction sludge concentration is controlled within 30g / L. The P-6# water inlet pump and the P-12# extraction water pump are started 5 times a day, each operation is 60min, and the membrane filtered water extracted by P-12# is sent to the biochemical effluent water tank; ammonium sulfate and glucose are added to the nitrogen source storage tank 13 and the carbon source storage tank 14 respectively. The daily dosage of the reagents is calculated according to the daily water inflow. The concentration of ammonia nitrogen added is 200 mg / L, and the concentration of glucose is 5000 mg / L. No nitrate nitrogen and sodium chloride are added; the daily dosage of the reagents is calculated as follows: assuming that the total reaction volume of anaerobic and aerobic is 50 m3, the hydraulic retention time is 10 d, and the daily water inflow is 5 m3, then the daily ammonia nitrogen dosage is 2 kg and the glucose dosage is 50 kg; open the V7# and V8# valves, close the V9# valve, and use the PLC time relay to control the operating frequency and time of the P-7# and P-8# metering pumps, running 5 times a day, each time for 60 minutes.

[0058] Sampling and analysis method: sampling is conducted at the inlet and outlet every 2 days to analyze the concentration values ​​of ammonia nitrogen, total nitrogen, COD and salinity. The stability of nitrification and denitrification activities and COD degradation performance is examined through the time variation trend of the concentration values ​​of ammonia nitrogen, total nitrogen, COD and salinity in the inlet and outlet water. The sludge concentration is measured every 10 days. When the sludge concentration exceeds 30 g / L, 20% of the aerobic sludge liquid can be discharged to the sludge storage tank 11 to reduce the sludge concentration and alleviate the impact of membrane fouling on the operation of the outlet pump. When the sludge layer height in the sludge storage tank 11 reaches 80% of the storage tank depth, the V-21# valve is opened to discharge 50% of the sludge in the storage tank to the sludge treatment equipment room for dehydration.

[0059] According to the daily mixed liquor influent volume to be treated and the nanofiltration concentrate content in the influent, a certain amount of electrolytic pretreatment nanofiltration concentrate is prepared according to the operation method 2-1. For example, when the content of electrolytic pretreatment nanofiltration concentrate in the influent is 50%, when the total anaerobic and aerobic reaction volume is 50m3, the hydraulic retention time is 10d, and the daily influent volume is 5m3, 2.5m3 of electrolytic pretreatment nanofiltration concentrate and 2.5m3 of reverse osmosis concentrate need to be mixed. If the electrolysis device processes 0.5m3 of nanofiltration concentrate every 2h, 5 batches of nanofiltration concentrate need to be electrolyzed every day, which needs to be completed within about 12h. The inlet pump is operated 5 times a day, once every 4h, and 1.0m3 of water is ingested each time (including 0.5m3 of electrolytic pretreatment nanofiltration concentrate). In this way, the daily amount of electrolytic pretreatment nanofiltration concentrate required should meet the influent volume requirements of the biochemical treatment system.

[0060] The content of the electrolytic pretreatment nanofiltration concentrate and the reverse osmosis concentrate in the mixed liquid in the water distribution tank 5 is first set to 33% and 67%, and is operated for 21-42 days. When the total nitrogen removal rate of the system effluent is stabilized at about 80%, it is adjusted to 50% and 50%. It is continued to operate until the total nitrogen removal rate of the system effluent is stabilized at about 80% again. It is considered that the anaerobic membrane bioreactor tank and aerobic membrane bioreactor tank treatment systems have entered the stable operation stage.

[0061] The pumped water is stored in the biochemical outlet water tank. During this period, the Y6-liquid level controller needs to be started to control the operation of the P-12# biochemical system water pump. When the liquid level in the biochemical outlet water tank reaches the liquid level height set by the Y6-liquid level controller, the P-12# pump is stopped.

[0062] (3) Fenton oxidation deep treatment operation method of biochemical effluent:

[0063] Open the V-14# valve, manually start the P-14# pump, start the Y7-liquid level controller, and send the biochemical effluent collected in the 9-biochemical effluent tank during (2) operation to the Fenton reaction tank 10. When the high liquid level of the Y7-liquid level controller is reached, the P-14# pump automatically stops running and the J2-agitator is started to run at a low speed to ensure that the reaction liquid is mixed with the added acid, alkali and Fenton reagent during the reaction process and quickly reach a completely mixed state. Open the V-16# valve, manually start the P-16# metering pump, and fill the acid storage tank 16 (prepared with 1-2 mol / L sulfur Acid solution) is fed into the Fenton reaction tank 10 at a low flow rate. When the reading of the pH meter 20 is observed to gradually decrease to 3 (the optimal pH value for the Fenton reaction), the V-16# valve is closed and the P-16# metering pump is stopped. The V-18# valve is opened and the P-18# metering pump is manually started to feed the ferrous sulfate storage tank (1.3 mol / L ferrous sulfate heptahydrate solution) into the Fenton reaction tank 10 at a low flow rate until the ferrous sulfate concentration in the reaction tank reaches 0.022 mol / L (the optimal ferrous sulfate concentration for the Fenton reaction). The V-18# valve is then closed and the P-18# metering pump is stopped. Pump, open V-17# valve, manually start P-17# metering pump, and send 17-hydrogen peroxide storage tank 19 (30% hydrogen peroxide solution) into 10-Fenton reaction tank 10 at a low flow rate until the hydrogen peroxide concentration in the reaction tank reaches 0.25mol / L (optimal hydrogen peroxide concentration for Fenton reaction), close V-17# valve, and stop P-17# metering pump; after the Fenton reagent addition operation is completed, start timing and continue stirring until the Fenton reaction reaches 2h, open V-16# valve, start P-16# metering pump, and send alkali solution storage tank 17 (0.2-0.4 mol / L sodium hydroxide solution), and send it into the Fenton reaction tank 10 at a low flow rate. When the reading of the 20-pH meter is observed to gradually rise to 7 (the pH needs to be adjusted back to neutral after the Fenton reaction is completed), close the V-16# valve, stop the P-16# metering pump, and the Fenton reaction operation is completed; open the V-19# valve, manually start the P-19# pump, and send all the Fenton deep-treated water in the Fenton reaction tank 10 into the clean water storage tank 12, close the V-19# valve, manually stop the P-19# pump, open the V-20# valve, and recharge the deep-treated water into the landfill.

[0064] The biochemical effluent was further treated with Fenton oxidation according to the above operation. The experimental results showed that the maximum COD removal rate could only reach 50%. Fenton oxidation could remove 50% of the non-biodegradable organic matter in the biochemical effluent of the leachate concentrate.

[0065] like Figure 3 、 4 As shown in , 5, and 6, the research results of the salt-tolerant sludge treatment process of raw water with different mixing ratios of electrolytic pretreatment nanofiltration membrane concentrate and reverse osmosis membrane concentrate can be summarized as follows:

[0066] (1) During the pre-acclimation of the sludge to sodium chloride salinity, the influent NaCl salinity was increased in a step-by-step manner (10-30 g / L). Both nitrification and denitrification sludges could tolerate the inhibitory effect of higher NaCl salinity, and the nitrification rate and total nitrogen removal rate could be maintained above 85% and 90%, respectively.

[0067] (2) Both the salt-tolerant nitrification and denitrification sludges can withstand the inhibitory effect of 50% electrolytic pretreatment nanofiltration membrane concentrate influent, and the nitrification rate and NO3--N removal rate can be maintained above 85% and 90%, respectively.

[0068] (3) After the electrolytic pretreatment nanofiltration membrane concentrate content increased from 67% to 75%, the removal rates of NH4+-N and NO3--N by salt-tolerant nitrification and denitrification sludge remained at around 50% and 70%, respectively, indicating that the nanofiltration membrane concentrate had a significant inhibitory effect on nitrifying bacteria and denitrifying bacteria in the acclimated sludge.

[0069] (4) When the concentration of the nanofiltration membrane concentrate in the influent electrolysis pretreatment changes from 33% to 75%, the COD degradation activity of the salt-tolerant acclimated sludge is basically not affected by the salinity inhibition of the concentrate.

[0070] like Figure 7 As shown in Figures 8 and 9, the results of the research on the experimental process parameters of the electrolytic pretreatment of nanofiltration concentrate showed that the optimal conditions for COD and salinity of the electrolytic pretreatment of landfill leachate nanofiltration membrane concentrate were: plate spacing of 1 cm, current density of 10 mA / cm2, and reaction time of 2 h.

[0071] like Figure 10 As shown in Figures 11 and 12, the research results on the process conditions of Fenton oxidation deep treatment of nanofiltration concentrate, reverse osmosis concentrate and biochemical effluent showed that the optimal conditions for Fenton oxidation operation were: n(H2O2):n(Fe2+) was 12, pH was 3, reaction time was 2h, and the maximum COD removal rates for nanofiltration concentrate, reverse osmosis concentrate and biochemical effluent were 80%, 70% and 50%, respectively.

[0072] Table 1 is the water quality table of the leachate membrane concentrate of the embodiment of the present invention.

[0073]

[0074]

[0075] Table 2 is a table showing the treatment effects of various treatment systems in the embodiments of the present invention (unit: mg / L)

[0076] The embodiments of this specific implementation method are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A landfill leachate membrane concentrate treatment system, comprising a pretreatment system, a biochemical system, and a deep oxidation treatment system, characterized in that: The pretreatment system consists of a membrane concentrate storage tank, an electrolytic reaction tank, an iridium-ruthenium coated electrode group, a regulated DC power supply, and a treatment liquid collection tank; The biochemical system includes a water distribution tank, an anaerobic membrane bioreactor tank, an aerobic membrane bioreactor tank, a nitrogen source storage tank, a carbon source storage tank, a sodium chloride storage tank and its supporting dosing pump, a sludge storage tank, and a treated water storage tank; The deep oxidation treatment system consists of a Fenton reaction tank, an acid storage tank, an alkali storage tank, a ferrous sulfate storage tank, a hydrogen peroxide storage tank and its supporting dosing pumps; The landfill leachate membrane concentrate includes nanofiltration membrane concentrate and reverse osmosis membrane concentrate. The nanofiltration membrane concentrate is first pre-treated in an electrolytic reactor. The nanofiltration membrane concentrate and reverse osmosis membrane concentrate are mixed in a water distribution tank at a ratio of 1:2 or 1:

1. The mixed liquid passes through an anaerobic membrane bioreactor and an aerobic membrane bioreactor to remove ammonia nitrogen, nitrate nitrogen and COD components from the concentrate. The anaerobic membrane bioreactor and aerobic membrane bioreactor are inoculated with pre-acclimated salt-tolerant sludge. The treated water is then deeply treated in a Fenton oxidation reactor to remove difficult-to-biodegrade COD. The effluent meets the recharge water quality standards of the landfill. During the pre-acclimation sludge operation stage, the treatment system uses the anaerobic tank and aerobic tank sludge from the municipal landfill leachate biochemical treatment facility as the seed sludge. Anaerobic membrane bioreactors and aerobic membrane bioreactors are used in a semi-continuous operation mode. The raw water with step-by-step salinity increase and the total nitrogen concentration and COD concentration consistent with those of the membrane concentrate is used to acclimate the seed sludge to improve its salt tolerance. The operating conditions and methods are as follows: Step S1: installing microfiltration flat membrane modules in both the anaerobic membrane bioreactor and the aerobic membrane bioreactor, with a membrane pore size of 2-3 microns, a volume ratio of the anaerobic membrane bioreactor to the aerobic membrane bioreactor of 1:2, a total hydraulic retention time of 5 days, a dissolved oxygen concentration of 0.2 mg / L or less in the anaerobic membrane bioreactor, a dissolved oxygen concentration of 2 mg / L or more in the aerobic membrane bioreactor, a circulation pump flow rate between the anaerobic membrane bioreactor and the aerobic membrane bioreactor of 2 times the daily water inflow, and a sludge concentration of 30 g / L or less; Step S2, add tap water to the water distribution tank, and the daily water inflow is calculated based on the hydraulic retention time of 5d. The nitrogen source storage tank is dosed with ammonium sulfate and potassium nitrate solution, the carbon source storage tank is dosed with glucose solution, and the sodium chloride storage tank is dosed with sodium chloride solution; the daily dosage of the reagent is calculated based on the daily water inflow, and the concentrations of the added ammonia nitrogen and nitrate nitrogen are 400 mg / L and 1000 mg / L respectively, the glucose concentration is 5000 mg / L, and the sodium chloride concentration is increased in steps of 10g / L, 15g / L, 20g / L, 25g / L, and 30g / L; Example of calculation of reagent dosage: assuming that the total reaction volume of the anaerobic membrane bioreactor and the aerobic membrane bioreactor is 50m3, the hydraulic retention time is 5d, and the daily water inflow is 10m3, then the dosages of ammonia nitrogen and nitrate nitrogen are 4kg and 10kg respectively, the dosage of glucose is 50kg, and the dosage of sodium chloride is 100kg, 150kg, 200kg, 300kg, 400kg, 500kg, 600kg, 700kg, 800kg, 900kg, 1000kg, 15 ... kg, 250 kg and 300 kg were increased stepwise, and the operation period for each additional concentration gradient was 10-15 days; Step S3, adopting an intermittent water inlet operation mode, with water inletting the anaerobic membrane bioreactor and water outlet from the aerobic membrane bioreactor, the raw water pump, the nitrogen source dosing pump, the glucose dosing pump, and the extraction water pump operating five times a day, each operating time for 60 minutes, the daily cumulative flow rates of the raw water pump and the extraction water pump being set according to the total reaction volume and the 5-day hydraulic retention time, the daily cumulative flow rates of the ammonia nitrogen, nitrate nitrogen dosing pump, and the glucose dosing pump being set according to the daily dosages of ammonia nitrogen, nitrate nitrogen, and glucose, and the membrane extraction water of the aerobic membrane bioreactor being sent to a water storage tank for storage; Step S4: Sampling is performed at the inlet and outlet every 2 days to analyze the concentrations of ammonia nitrogen, total nitrogen, COD, and salinity. The sludge concentration is measured every 10 days. When the sludge concentration exceeds 30 g / L, 20% of the sludge liquid from the aerobic membrane bioreactor is discharged. When the sodium chloride concentration is increased to 30 g / L and the system is operated until the total nitrogen removal rate of the effluent is stabilized at more than 80%, the sludge pre-acclimation operation phase ends.

2. The landfill leachate membrane concentrate treatment system according to claim 1, characterized in that: The electrolytic pretreatment operation method of nanofiltration membrane concentrate is as follows: Step 1: The nanofiltration membrane concentrate is fed into the electrolytic reaction tank, and the blower is started to send air into the bottom of the electrolytic reaction tank, so that small bubbles are formed through the porous tubes arranged at the bottom to produce a weak stirring effect; Step 2: Place the positive and negative electrode plates crosswise with a spacing of 1 cm between the plates. The surface of the electrode plates is coated with an iridium-ruthenium alloy film, which has good conductivity and corrosion resistance. The service life of the plates is more than 1000 hours. Turn on the regulated DC power supply, use a constant current, set the current density to 10 mA / cm2, and the electrolysis reaction time is 2 hours. Step 3: Turn off the blower, manually start the infusion pump, and send the electrolytically pretreated nanofiltration membrane concentrate into the water distribution tank; The preparation method of the mixed solution of electrolytic pretreatment nanofiltration membrane concentrate and reverse osmosis membrane concentrate is as follows: The nanofiltration membrane concentrate obtained by electrolysis pretreatment and the reverse osmosis membrane concentrate in the reverse osmosis membrane concentrate storage tank are adjusted according to the ratio of the liquid level height of the nanofiltration membrane concentrate obtained by electrolysis pretreatment to the liquid level height of the reverse osmosis membrane concentrate in the water distribution tank. When the liquid level ratios are 1:2 and 1:1 respectively, the content ratios of the nanofiltration membrane concentrate obtained by electrolysis pretreatment and the reverse osmosis membrane concentrate in the mixed liquid in the water distribution tank are 33% and 67%, and 50% and 50% respectively. In the case of electrolytic pretreatment of nanofiltration membrane concentrate and reverse osmosis membrane concentrate with a water content of 50%, when the total anaerobic and aerobic reaction volume is 50m 3 , hydraulic retention time is 10d, daily water inflow is 5m 3 2.5m is required 3 Electrolytic pretreatment of nanofiltration membrane concentrate and 2.5m 3 Reverse osmosis membrane concentrate is mixed, such as the electrolysis device processes 0.5 m of nanofiltration membrane concentrate every 2 hours 3 , then 5 batches of nanofiltration membrane concentrate need to be electrolyzed every day, which needs to be completed within 12 hours. The water inlet pump needs to be run 5 times a day, once every 4 hours, and 1.0 m3 of water needs to be fed each time. 3 , which contains 0.5 m of electrolytic pre-treated nanofiltration membrane concentrate 3 , the total amount of electrolytic pretreatment nanofiltration membrane concentrate that can be prepared per day is 2.5m 3 .

3. The landfill leachate membrane concentrate treatment system according to claim 1, characterized in that: The treatment system is in the startup operation stage of treating the mixed liquor of the nanofiltration membrane concentrate and the reverse osmosis membrane concentrate: the mixed liquor of the nanofiltration membrane concentrate and the reverse osmosis membrane concentrate that have been pretreated by electrolysis is added to the water distribution tank, and the operation method and conditions of the anaerobic membrane bioreactor and the aerobic membrane bioreactor described in step S1 are followed, and the hydraulic retention time is calculated as 10 days. The nitrogen source storage tank is only dosed with ammonium sulfate solution, and the carbon source storage tank is dosed with glucose solution. The daily dosage of the reagent is calculated according to the daily water inflow. The added ammonia nitrogen concentration is 200 mg / L, and the glucose concentration is 5000 mg / L. The content of the electrolytic pretreated nanofiltration membrane concentrate and the reverse osmosis membrane concentrate in the mixed liquor in the water distribution tank is first set to 33% and 67%, and the system is operated for 21-42 days. When the total nitrogen removal rate of the system effluent stabilizes at 80%, the nitrogen removal rate is adjusted to 50% and 50%, and the operation is continued until the total nitrogen removal rate of the system effluent stabilizes at 80% again. It is considered that the anaerobic membrane bioreactor and the aerobic membrane bioreactor treatment system enter the stable operation stage; Sampling is done at the inlet and outlet every 2 days to analyze the concentrations of ammonia nitrogen, total nitrogen, COD and salinity. The sludge concentration is measured every 10 days. When the sludge concentration exceeds 30g / L, 20% of the sludge liquid from the aerobic membrane bioreactor is discharged. Run the raw water pump, nitrogen source dosing pump, glucose dosing pump, and water extraction pump according to the operation method described in step S3; The pumped water is stored in the biochemical effluent tank.

4. The landfill leachate membrane concentrate treatment system according to claim 1, characterized in that: The Fenton oxidation process is used to deeply treat the effluent from the anaerobic membrane bioreactor and aerobic membrane bioreactor in the biochemical effluent tank. The operation method is as follows: The biochemical effluent in the biochemical effluent tank is sent to the Fenton reaction tank, the agitator is started to run at a low speed, the acid storage tank metering pump is started, and the sulfuric acid solution is sent to the Fenton reaction tank at a low flow rate. When the reading of the pH meter is observed to gradually decrease to 3, the acid storage tank metering pump is stopped; the ferrous sulfate storage tank metering pump is started, and the ferrous sulfate solution is sent to the Fenton reaction tank at a low flow rate. When the ferrous sulfate concentration in the reaction tank is 0.022 mol / L, the ferrous sulfate storage tank metering pump is stopped; the hydrogen peroxide storage tank metering pump is started, and the hydrogen peroxide is sent to the Fenton reaction tank at a low flow rate. When the hydrogen peroxide concentration in the reaction tank is 0.25 mol / L, the hydrogen peroxide storage tank metering pump is stopped; the timing is started, and stirring is continued until the Fenton reaction reaches 2 hours, the alkali solution storage tank metering pump is started, and the alkali solution is sent to the Fenton reaction tank at a low flow rate. The pH meter reading is observed to gradually rise to 7, and the alkali solution storage tank metering pump is stopped; the Fenton reaction tank infusion pump is started to send all the treated water in the tank into the clean water storage tank.

Images