A high-salt landfill leachate biochemical treatment microorganism maintenance and full-quantitative treatment method

Abstract

The application provides a high-salt landfill leachate biochemical treatment microorganism maintenance and full-quantitative treatment method, which comprises the following steps: subjecting high-salt landfill leachate to biochemical AO treatment through a biochemical AO system, subjecting effluent obtained through the biochemical AO treatment to treatment through an AO microorganism maintenance system, obtaining first clear liquid and first thick liquid, subjecting the first clear liquid to backflow to the front end of a denitrification tank through a desalted water backflow system; subjecting sludge water obtained through the biochemical AO treatment to sludge water adjustment treatment, completing sludge water separation in a sedimentation tank, obtaining second clear liquid and first sludge, subjecting part of the first sludge to sludge treatment, and subjecting part of the first sludge to backflow to the front end of the denitrification tank; mixing the first clear liquid and the second clear liquid in a buffer tank, and pumping sewage in the buffer tank into a deep treatment system to flow into a clear water tank after reaching a standard. The application reduces the salt concentration of the AO system through the desalination function of the microorganism maintenance system, realizes the normal biochemical function of the biochemical AO system, does not produce high-salt wastewater backfilling, and realizes the balance between salt production of raw leachate and salt discharge of treated water.

Description

Technical Field

[0001] This invention relates to the field of high-salinity wastewater treatment technology, and in particular, to a method for the maintenance and full-scale treatment of microorganisms in the biochemical treatment of high-salinity landfill leachate. Background Technology

[0002] The treatment of leachate from municipal landfills has always been a very challenging problem in landfill design, operation, and management. Leachate is a product of gravity flow of liquids within the landfill, primarily originating from precipitation and the water content within the waste itself.

[0003] Landfill leachate has characteristics that differ from general urban wastewater: high BOD5 and COD concentrations, high metal content, large fluctuations in water quality and quantity, high ammonia nitrogen content, and an imbalance in the ratio of nutrients for microorganisms. Past leachate treatment processes have primarily relied on imported membrane treatment systems, employing pretreatment + biological treatment + membrane (UF + RO) systems or pretreatment + membrane systems (two-stage DTRO membranes). The concentrate has a high chloride ion concentration, and if reinjected into the equalization tank, the overall system salt concentration gradually increases, treatment becomes more difficult, effluent flow decreases, and a large accumulation of high-salt leachate occurs. Using MVR evaporation and cement kiln incineration to treat the concentrate is generally unacceptable due to high costs. If a biological AO system is used to treat high-salt landfill leachate, the microorganisms cannot survive, making biological treatment difficult. Currently, landfill leachate treatment plants using RO membrane systems have accumulated large amounts of concentrate or reinjected into equalization tanks, resulting in chloride ion concentrations in these tanks exceeding 5000 mg / L, typically ranging from 7000 to 10000 mg / L. This high-salt leachate poses a significant potential environmental pollution risk to landfill treatment plants; therefore, the proper treatment of this high-salt leachate is an important environmental protection task.

[0004] Chloride ion concentrations in common wastewater exceeding 4000 mg / L will have a certain toxic effect on the microorganisms in biological treatment systems; for example, when the chloride ion concentration in an aqueous solution is above 5000 mg / L, the osmotic pressure will increase to approximately 10. -30 At atmospheric pressure, under such high osmotic pressure, a large amount of water molecules within the microorganisms will permeate into the external solution, causing cell dehydration and plasmolysis, and in severe cases, microbial death. Engineering experience data shows that when the chloride ion concentration in wastewater exceeds 2000 mg / L, microbial activity is inhibited, and the COD removal rate decreases significantly; when the chloride ion concentration in wastewater exceeds 8000 mg / L, it causes sludge volume expansion, a large amount of foam to appear on the water surface, and the microorganisms subsequently die. Summary of the Invention

[0005] To address the problem of microbial toxicity to biochemical treatment systems caused by high-salt wastewater or concentrate in existing technologies, this invention provides a method for the maintenance and full-scale treatment of microorganisms in the biochemical treatment of high-salt landfill leachate. By reducing the salt concentration of the AO system through the desalination function of the desalination system, the normal biochemical function of the biochemical AO system is achieved. This avoids the re-injection of high-salt wastewater and balances the salt production from the raw leachate and the salt discharge from the treated water, thereby solving the problem that high-salt landfill leachate or concentrate is difficult to treat using a biochemical AO system.

[0006] To achieve the above objectives, the present invention provides a method for the maintenance and full-scale treatment of microorganisms in the biochemical treatment of high-salt landfill leachate, comprising the following steps:

[0007] Step 1: The high-salt waste leachate is sequentially subjected to denitrification and nitrification treatment through the biochemical AO system, with a portion being recycled back to the front end of the denitrification process;

[0008] Step 2: The effluent obtained in Step 1 is treated by the AO microbial maintenance system to obtain the first clear liquid and the first concentrated liquid. The first clear liquid is returned to the front end of the denitrification tank through the desalination water return system.

[0009] Step 3: The mud and water obtained in Step 1 are treated with mud and water conditioning. The sedimentation tank completes the mud and water separation to obtain the second clear liquid and the first sludge. Part of the first sludge is treated as sludge, and part is returned to the front end of the denitrification.

[0010] In step 4, the first clear liquid obtained in step 2 and the second clear liquid obtained in step 3 are mixed in a buffer tank. The wastewater in the buffer tank is then pumped sequentially into the Fenton system, the filter system, and the activated carbon system before flowing into the clear water tank after meeting the standards.

[0011] Furthermore, prior to step 1, the process includes: pre-treatment of the high-salt landfill leachate, specifically adjusting the pH value and performing filtration.

[0012] Furthermore, in step 2, the chloride ion concentration in the first clear solution is lower than that in the first concentrated solution.

[0013] Furthermore, in step 4, the wastewater from the buffer tank is sequentially pumped into the Fenton system for Fenton treatment. The organic pollutants that are difficult to biodegrade in the first concentrated liquid and the second clear liquid are oxidized by hydroxyl radicals generated by adding ferrous sulfate and hydrogen peroxide, resulting in the third clear liquid and the second sludge.

[0014] Furthermore, in step 4, the third clear liquid is treated by the filter system. The suspended solids (SS) in the third clear liquid are removed by nitrification and denitrification, and COD is removed by oxidation, resulting in the fourth clear liquid and the third type of sludge. After the fourth clear liquid meets the standards, it is discharged into the qualified water discharge system.

[0015] Furthermore, in step 4, the fourth clear liquid is treated with activated carbon by an activated carbon system. The activated carbon further adsorbs the recalcitrant organic matter in the fourth clear liquid to obtain the fifth clear liquid, which is discharged in compliance with standards.

[0016] Furthermore, the sludge obtained in step 3 is dewatered through a sludge dewatering system. Specifically, sludge-water separation is achieved by filter cloth interception, resulting in fourth sludge and sixth clear liquid. The fourth sludge is disposed of in a sanitary landfill, while the sixth clear liquid is reinjected into the sedimentation system for further processing.

[0017] Furthermore, in step 2, the desalination nitrification liquor reflux flow rate, i.e., the first clear liquor volume, is calculated as follows:

[0018] (Q 原水 *m 原水盐浓度 +R 脱盐回流水 *m 脱盐后盐浓度 ) / (Q 原水 +R 脱盐回流水 *Q 原水 ) = m 控制盐浓度 Q 原水 ---AO system raw water inflow, m 3 / h;

[0019] m 原水盐浓度 ---Initial influent salt ion concentration, mg / L;

[0020] R 脱盐回流水 ---Return ratio of wastewater with low salt ion concentration after desalination;

[0021] m 脱盐后盐浓度 ---Low ion concentration wastewater after desalination, mg / L;

[0022] m 控制盐浓度 ---The concentration of salt ions that need to be controlled in the AO biochemical system.

[0023] Furthermore, the first concentrated liquid volume in step 2 is calculated as follows:

[0024] 20% = Q 浓液 / Q 清液

[0025] Q 浓液 =20% * Q 清液

[0026] Q 浓液 ---Concentrated solution permeate, m 3 / h;

[0027] Q 清液 ---Clear liquid production rate, m 3 / h.

[0028] 80% --- The ratio of clear liquid to concentrated liquid produced by the desalination unit.

[0029] Furthermore, the sludge return flow rate is calculated as follows:

[0030] Q 污泥 =100% * Q 原水

[0031] Q 污水 ---Raw water inflow, m 3 / h;

[0032] Q 污泥 ---Sludge return flow rate, m 3 / h.

[0033] The present invention has the following beneficial effects:

[0034] (1) The salt ions in the raw water are temporarily extracted, creating a wastewater environment with a low salt concentration (3500 mg / L chloride ions) for the AO system. This prevents the water in the cells of microorganisms such as Bacillus, nitrifying bacteria, denitrifying bacteria, and actinomycetes in the biochemical system from actively diffusing into the wastewater. As a large number of microorganisms survive, they oxidize and decompose organic matter such as COD and obtain phosphorus pollutants to synthesize cells. The removal of total nitrogen is achieved through nitrification and denitrification.

[0035] (2) Temporarily reducing the salt concentration (removing chloride ions from the AO system) can treat high-concentration landfill leachate wastewater. Currently, the RO membrane process makes it impossible to treat high-salt landfill wastewater in the equalization tank and reservoir to meet discharge standards. Continuing to store it poses an environmental risk of spillage. Using MVR evaporation will consume a lot of energy and is economically unreasonable. The biochemical treatment method for high-salt landfill leachate provided by this invention, which involves microbial maintenance and full-scale treatment, will solve the problems of high-salt wastewater treatment costs and spillage risks.

[0036] (3) The AO microbial maintenance system in the biochemical treatment microbial maintenance and full-scale treatment method of high-salt landfill leachate provided by the present invention creates a low-salt environment (chloride ion) environment for the AO system, realizes the function of biochemical treatment of pollutants, reduces the pressure on subsequent deep treatment, and realizes the reagent cost of Fenton oxidation and the replacement frequency of activated carbon in deep treatment.

[0037] (4) This invention mainly uses an AO microbial maintenance system with disc filters to intercept salt ions (chloride ions) in the AO system, thereby reducing the salt concentration (chloride ions) in the AO system and activating the activity of microorganisms. This transforms high-salt leachate that cannot be biochemically treated into biochemically treatable wastewater, greatly reducing the cost of physical treatment. In addition, this invention adopts a full-volume treatment method. After the high-salt leachate enters the AO biochemical system, the salt is separated into two parts by the AO microbial maintenance system. One part is the low-salt wastewater that is returned to the front end of the AO system to dilute the high-salt leachate and protect the microorganisms in the AO system. The biochemical effluent is then mixed with the other part of the high-salt wastewater for further treatment to meet discharge standards. There is no reinjection of high-salt concentrated wastewater, achieving a balance between the inflow and outflow of wastewater and the inflow and outflow of salt ions in the wastewater.

[0038] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description

[0039] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0040] Figure 1 A simplified flowchart of a method for the maintenance and full-scale treatment of microorganisms in the biochemical treatment of high-salt landfill leachate provided by the present invention;

[0041] Figure 2 This invention provides a detailed flowchart of a method for the biochemical treatment of high-salt landfill leachate, including microbial maintenance and full-scale treatment. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of the embodiments of the invention clearer, the process solutions of the embodiments of the invention will be clearly and completely described below with reference to the accompanying drawings.

[0043] Furthermore, the terms “first” and “second” are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated.

[0044] This invention provides a method for the biochemical treatment of high-salinity landfill leachate, including microbial maintenance and full-scale treatment. The apparatus comprises a pretreatment system, a biochemical AO system, a sludge-water conditioning system, an AO microbial maintenance system, a buffer tank, a deep treatment system, a clear water tank, and a sludge dewatering system, all interconnected. The biochemical AO system includes denitrification, nitrification, and internal reflux systems; the AO microbial maintenance system includes a biological maintenance pretreatment system, a microbial maintenance system, and a sludge-water conditioning system; and the deep treatment system includes a Fenton system, a filter system, and an activated carbon adsorption system.

[0045] like Figure 1 and Figure 2 As shown in the figure, this invention provides a method for the maintenance and full-scale treatment of microorganisms in the biochemical treatment of high-salt landfill leachate. The process includes the following steps:

[0046] Step 1: Pre-treat the high-salt landfill leachate to adjust its physicochemical properties and remove suspended solids and large particulate pollutants (suspended solids and large particulate pollutants with a density less than water are intercepted by a screen, while suspended solids and large particulate pollutants with a density greater than water settle in the equalization tank, and the sludge at the bottom of the equalization tank is cleaned regularly).

[0047] Specifically, the physicochemical properties of high-salinity landfill leachate can be adjusted during pretreatment; for example, the pH value can be adjusted to 7-9. In this embodiment, suspended solids and large particulate pollutants can be removed from the high-salinity landfill leachate through a basket filter. At the same time, the equalization tank uses a large volume to mix wastewater with different pH values ​​before and after treatment, reducing large fluctuations in pH value and ensuring the water quality requirements of the high-salinity landfill leachate when it enters the next stage of treatment.

[0048] Step 2: The pretreated high-salt waste leachate is sequentially subjected to denitrification and nitrification treatments through the biochemical AO system, with a portion being recycled back to the denitrification front end.

[0049] Denitrification can decompose some COD pollutants, ammonify organic nitrogen, and complete the denitrification process by refluxing the nitrification liquid. Specifically, denitrifying bacteria reduce nitrates to nitrogen gas under the condition of providing a carbon source to achieve the denitrification function; at the same time, organic pollutants are decomposed into CO2 and H2O or some low molecular weight organic matter under the action of anaerobic bacteria.

[0050] Nitrification can oxidize and decompose part of COD, ammonify organic nitrogen, and nitrify ammonia nitrogen; the nitrification products are nitrates and nitrites, etc. Specifically, nitrifying bacteria reduce ammonia nitrogen to nitrates with the assistance of O2; at the same time, organic pollutants are decomposed into CO2 and H2O or some low molecular weight organic matter under the action of aerobic bacteria; the reflux of nitrification liquid provides a large amount of nitrates and other substances for denitrification.

[0051] The pretreated leachate reacts in a multi-stage AO system to remove pollutants such as COD, ammonia nitrogen, total nitrogen, and phosphorus from high-salinity landfill leachate. Specifically, through multi-stage anoxic-aerobic tank reactions, organic nitrogen is converted to ammonia nitrogen via ammonification, then ammonia nitrogen is nitrified to nitrate, and finally nitrate is denitrified back to nitrogen gas, achieving denitrification. Part of the COD is converted to inorganic substances such as CO2 and H2O through oxidation reactions in the anoxic-aerobic tanks. Phosphorus is removed from the wastewater through anaerobic release and aerobic dilution. Not only can nitrified liquor be recycled, but sludge can also be recycled to maintain the system's sludge concentration, while excess sludge is pumped out to a sludge tank. The specific recycling flow rate is calculated based on the wastewater quality and the formulas: nitrified liquor recycling flow rate calculation and sludge recycling flow rate calculation.

[0052] Step 3: The effluent obtained in Step 1 is treated by the AO microbial maintenance system to obtain a first clear liquid (with a small amount of chloride ions) and a first concentrated liquid (with a large amount of chloride ions). The first clear liquid is returned to the front end of the denitrification tank through the demineralized water return system. The biological maintenance pretreatment system and the microbial maintenance system achieve the separation of large particulate impurities and the chloride ion interception effect of the physical membrane, resulting in the first concentrated liquid and the first clear liquid. The first clear liquid is injected into the denitrification tank through the demineralized water return system, which reduces the salt ion concentration in the AO system.

[0053] Specifically, the leachate treated by the biochemical AO system removes most of the organic matter, nitrogen, and phosphorus, and then re-enters the biological pretreatment system to meet the influent water quality requirements of the biological pretreatment system. The wastewater flowing through the biological pretreatment system is pumped into the RO membrane, the main equipment of the biological pretreatment system. Through the physical separation principle of reverse osmosis, the concentrated brine and clear water are separated to obtain the first clear liquid (with a small amount of chloride ions) and the first concentrated liquid (with a large amount of chloride ions). The first clear liquid is returned to the front end of the denitrification system through the desalination nitrification liquid return system. The return flow rate is approximately 100%-200% of the influent flow rate, which can dilute the chloride ions of about 10,000 mg / L to below 5,000 mg / L. The specific calculation value is based on the water quality and the desalination nitrification liquid return flow rate.

[0054] Step 4: The mud and water obtained in Step 1 are subjected to mud and water conditioning treatment. The sedimentation tank completes the mud and water separation to obtain the second clear liquid and the first sludge. Part of the first sludge is treated as sludge, and part is returned to the front end of the denitrification.

[0055] In step 5, the first clear liquid obtained in step 2 and the second clear liquid obtained in step 3 are mixed in a buffer tank. The wastewater in the buffer tank is then pumped sequentially into a deep treatment system (including a Fenton system, a filter system, and an activated carbon system connected in sequence) and flows into a clear water tank after meeting the standards.

[0056] Wastewater from the buffer tank is sequentially pumped into the Fenton system for Fenton treatment. The organic pollutants that are difficult to biodegrade in the first concentrated liquid and the second clear liquid are oxidized by hydroxyl radicals generated by adding ferrous sulfate and hydrogen peroxide, resulting in the third clear liquid and the second sludge.

[0057] The third clear liquid is treated in the filter system. The suspended solids (SS) in the third clear liquid are removed by nitrification and denitrification, and COD is removed by oxidation, resulting in the fourth clear liquid and the third type of sludge. The fourth clear liquid meets the standards and can be discharged into the qualified water discharge system.

[0058] The fourth clear liquid is treated with activated carbon by an activated carbon system. The activated carbon further adsorbs the recalcitrant organic matter in the fourth clear liquid to obtain the fifth clear liquid, which is discharged in compliance with standards.

[0059] Specifically, the first and second clear liquids are mixed in a mixing tank and then pumped into the Fenton treatment system via a pump set (flow meter and valves). The Fenton system uses hydroxyl radicals generated by the addition of ferrous sulfate and hydrogen peroxide to oxidize recalcitrant organic matter. The mud-water mixture is separated by PAM coagulation when the pH is adjusted by alkali. The sludge is discharged into the sludge tank, and the wastewater flows by gravity into the filter system to further remove pollutants such as COD, ammonia nitrogen, total nitrogen, and SS. The wastewater treated by the filter enters the activated carbon to further adsorb pollutants through the carbon pores. After meeting the standards, it flows into the clear water tank for discharge.

[0060] Step 6: Excess AO sludge and Fenton chemical sludge are dewatered through a sludge dewatering system. The sludge is dewatered using a plate and frame filter press, and the sixth clarified liquid after plate and frame filtration is returned to the first stage of the multi-stage AO system. Alternatively, sludge-water separation can be achieved through filter cloth interception, yielding a fourth type of sludge (low moisture content) and a sixth clarified liquid. The fourth type of sludge is disposed of in a sanitary landfill, while the sixth clarified liquid is reinjected into the sedimentation system for further treatment.

[0061] In the invention's method for the biochemical treatment of high-salt landfill leachate, including microbial maintenance and full-scale treatment, the reflux flow rate is calculated as follows:

[0062] ① Total return flow calculation:

[0063] Q 回流泥水 =Q 原水 *R 总

[0064] R 总 =(TN 进水 -TN 出水 ) / TN 出水

[0065] Q 回流泥水 ---The sum of the three types of sludge-water mixtures: returned sludge, returned nitrified liquor, and returned desalination nitrified liquor, m 3 / h;Q 污水---Raw water inflow, m 3 / h;

[0066] TN 进水 ---Total nitrogen in raw water in biological treatment tank A, mg / L;

[0067] TN 出水 ---Total nitrogen in the effluent from the biological O-treatment tank, mg / L;

[0068] ② Calculation of desalination and nitrification liquor reflux flow rate (first clear liquor volume):

[0069] (Q 原水 *m 原水盐浓度 +R 脱盐回流水 *m 脱盐后盐浓度 ) / (Q 原水 +R 脱盐回流水 *Q 原水 ) = m 控制盐浓度 Q 原水 ---AO system raw water inflow, m 3 / h;

[0070] m 原水盐浓度 ---Initial influent salt ion concentration, mg / L;

[0071] R 脱盐回流水 ---Return ratio of wastewater with low salt ion concentration after desalination;

[0072] m 脱盐后盐浓度 ---Low ion concentration wastewater after desalination, mg / L;

[0073] m 控制盐浓度 The salt ion concentrations that need to be controlled in the AO biochemical system can be set to 3500 mg / L, 4000 mg / L, or 5000 mg / L.

[0074] ③ Calculation of sludge return flow:

[0075] Q 污泥 =100% * Q 原水

[0076] Q 污水 ---Raw water inflow, m 3 / h;

[0077] Q 污泥 ---Sludge return flow rate, m 3 / h.

[0078] ④ Calculation of nitrification liquid reflux flow rate:

[0079] Q 硝化液回流量 =(R 总 -100%-R 脱盐回流水 )*Q原水

[0080] ⑤ Calculation of the first concentrated liquid volume:

[0081] 20% = Q 浓液 / Q 清液

[0082] Q 浓液 =20% * Q 清液

[0083] Q 浓液 ---Concentrated solution permeate, m 3 / h;

[0084] Q 清液 ---Clear liquid production rate, m 3 / h.

[0085] 80% --- The ratio of clear liquid to concentrated liquid produced by the desalination unit.

[0086] The present invention will be described in detail below with reference to specific embodiments.

[0087] A landfill leachate treatment plant has a treatment capacity of 100m³. 3 / d, originally there was a box-type DTRO membrane treatment for leachate that had been refilled with a large amount of concentrated chloride ions; now, after renovation, the high-salt leachate is treated using a multi-stage AO biological system + MBR ultrafiltration membrane system + AO microbial maintenance system (desalination device) + buffer tank + deep treatment system (two-stage Fenton + filter + activated carbon) process. The influent water quality is shown in Table 1.

[0088] Table 1:

[0089] Serial Number Water quality indicators Total inflow values Total water output value unit 1 PH 6.8-8.5 6.0-9.0 2 COD 1500-2000 ≤100 mg / L 3 BOD 200-600 ≤25 mg / L 4 chloride ions 10000 ≤10000 mg / L 5 ammonia nitrogen 1200-1500 ≤25 mg / L 6 Total nitrogen 1300-1600 ≤40 mg / L

[0090] The present invention provides a method for the maintenance and full-scale treatment of microorganisms in the biochemical treatment of high-salt landfill leachate for a 100m³ site. 3 The high-salinity landfill leachate is treated as follows:

[0091] 1) Pretreatment: A large-volume equalization tank adjusts the pH of the water to 6-9, which is conducive to AO microorganisms. A basket filter intercepts large particles of debris in the sewage to protect the subsequent sewage pumps and pipelines.

[0092] 2) A two-stage AO (with chloride ion concentration controlled at 3500 mg / L) + MBR unit + AO microbial maintenance system (the chloride ion concentration in the clean water after desalination is set at 50 mg / L). The pretreated high-salt landfill leachate wastewater enters the two-stage AO + MBR unit + AO microbial maintenance system for further treatment. Specifically...

[0093] The reflux calculation is as follows:

[0094] a. Total AO reflux ratio (Level 1):

[0095] R 总 =(TN 进水 -TN 出水 ) / TN 出水 =(1600-229) / 219=6.3

[0096] b. Total AO reflux ratio (secondary):

[0097] R 总 =(TN 进水 -TN 出水 ) / TN 出水 =(219-30) / 30 = 6.3

[0098] Take the total reflux ratio of the MBR unit as R 总 =6.3

[0099] c. Sludge return ratio:

[0100] R 污泥 =100%=1.0

[0101] d. Calculation of desalination nitrification liquor reflux ratio:

[0102] (Q 原水 *C 原水盐浓度 +Q 原水 *R 脱盐回流水 *C 脱盐后盐浓度 ) / (Q 原水 +R 脱盐回流水 *Q 原水 ) = C 控制盐浓

[0103] Spend

[0104] (4.166*10000+4.166*R 脱盐回流水 *50) / (4.166+R 脱盐回流水 *4.166)=3500

[0105] Launch R 脱盐回流水 =1.88

[0106] e. Calculation of nitrification liquor return flow rate:

[0107] R 硝化液回流量 =R 总 -100%-R 脱盐回流水 =6.3 - 1.0 - 1.88 = 3.42

[0108] f. First concentrate product water yield:

[0109] Q浓液 =20% * Q 清液 =0.2 * 1.88 * 4.16 = 1.56 m³ / h

[0110] g. Calculate the chloride ion concentration of the concentrated solution based on chloride ion equilibrium:

[0111] 10000*(1.88*4.16+1.88*4.16*0.2)=1.88*4.16*50+C 浓液 *1.88*4.16*0.2

[0112] Launch C 浓液 =59750mg / L

[0113] According to the present invention, a method for the biochemical treatment of high-salinity landfill leachate using microbial maintenance and full-scale treatment was used to treat the above-mentioned high-salinity landfill leachate wastewater. The two-stage AO sludge return flow rate was 4.16 m³ / s. 3 / h, desalination nitrification liquor reflux is 7.82m 3 / h, nitrification liquor reflux 14.22m 3 / h, first concentrate production water rate 1.56m³ 3 / h. The chloride ion concentration of the first supernatant is 50 mg / L, and the chloride ion concentration of the first concentrate is 59750 mg / L.

[0114] The effluent quality of the MBR is shown in Table 2:

[0115] Table 2:

[0116]

[0117]

[0118] The MBR permeate flow rate is 11.98 m³. 3 / h; of which 2.6m 3 / h wastewater enters the buffer tank, 9.38m 3 Wastewater is treated in a desalination unit at a rate of 1.56 m³ / h. 3 / h, the first supernatant (desalinated nitrified liquid) is 7.82m³. 3 / h.

[0119] The mixed water quality in the buffer tank is shown in Table 3: (2.6m³ of MBR permeate water enters the buffer tank) 3 / h, while the first concentrate enters at 1.56m 3 / h)

[0120] Table 3:

[0121]

[0122] 3) Advanced treatment system (two-stage Fenton filter + activated carbon)

[0123] The effluent from the buffer tank is pumped into a two-stage Fenton system. After adding ferrous sulfate, hydrogen peroxide, caustic soda, and PAM, it flows into the filter to remove suspended solids (SS) and some pollutants. Pollutants that cannot be removed by Fenton advanced oxidation can be adsorbed by activated carbon filter and discharged in compliance with standards.

[0124] The water quality at each stage is shown in Table 4:

[0125] Table 4:

[0126]

[0127]

[0128] As shown in Table 4, the water quality after deep treatment by the advanced treatment system (specifically, two-stage Fenton + filter + activated carbon) meets the discharge standards.

[0129] In summary, this invention provides a method for the maintenance and full-scale treatment of high-salt landfill leachate through microbial processes. This method solves the problem of the toxic effects of high-salt wastewater or concentrate on the microorganisms in the biological treatment system. By reducing the salt concentration in the AO system through the desalination function of the desalination system, the normal biological functions of the AO system are achieved. This avoids the re-injection of high-salt wastewater, thus achieving a balance between salt production from the leachate raw water and salt discharge from the treated water. This invention employs a full-scale treatment method. After the high-salt leachate enters the AO biological system, the salt is separated into two parts by the AO microbial maintenance system. One part, low-salt wastewater, is returned to the front end of the AO system to dilute the high-salt leachate, protecting the microorganisms in the AO system. The biochemical effluent is then mixed with the other part of the separated high-salt wastewater for further treatment to meet discharge standards. There is no re-injection of high-salt concentrated wastewater, achieving a balance between wastewater volume and salt ion inflow and outflow. This invention uses an AO microbial maintenance system with disc filters to intercept salt ions (chloride ions) in the AO system, thereby reducing the salt concentration (chloride ions) in the AO system and activating the activity of microorganisms. This transforms high-salt leachate that cannot be biochemically treated into biochemically treatable wastewater, greatly reducing the cost of physical treatment.

[0130] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for the maintenance and full-scale treatment of microorganisms in the biochemical treatment of high-salt landfill leachate, characterized in that, Includes the following steps: Step 1: The high-salt landfill leachate is subjected to denitrification and nitrification treatment sequentially through the biochemical AO system, with a portion of the nitrified liquid being recycled back to the front end of the denitrification process; Step 2: The effluent obtained in Step 1 is desalinated by the AO microbial maintenance system to obtain a first clear liquid and a first concentrated liquid. The first clear liquid is returned to the front end of the denitrification tank through the desalination water return system to regulate the salt ion concentration in the denitrification tank and maintain the activity of denitrifying microorganisms. The first concentrated liquid is not reinjected to the front end of the biological AO system. Step 3: The mud and water obtained in Step 1 are treated with mud and water conditioning, and the mud and water are separated in a sedimentation tank to obtain the second clear liquid and the first sludge. Part of the first sludge is treated as sludge, and part is returned to the front end of the denitrification. In step 4, the first concentrated liquid obtained in step 2 and the second clear liquid obtained in step 3 are mixed in a buffer tank. The wastewater in the buffer tank is then pumped sequentially into the Fenton system, the filter system, and the activated carbon system. After meeting the standards, the wastewater flows into the clear water tank, thus achieving a total balance between the salt production from the leachate raw water and the salt discharge from the treated water.

2. The method for microbial maintenance and full-scale treatment of high-salt landfill leachate according to claim 1, characterized in that, Before step 1, the process also includes: pretreatment of the high-salt landfill leachate, specifically pH adjustment and filtration.

3. The method for microbial maintenance and full-scale treatment of high-salt landfill leachate according to claim 1, characterized in that, In step 2, the chloride ion concentration in the first clear solution is lower than that in the first concentrated solution.

4. The method for microbial maintenance and full-scale treatment of high-salt landfill leachate according to claim 1, characterized in that, In step 4, the wastewater in the buffer tank is pumped into the Fenton system for Fenton treatment. The organic pollutants that are difficult to biodegrade in the first concentrated liquid and the second clear liquid are oxidized by hydroxyl radicals generated by adding ferrous sulfate and hydrogen peroxide, resulting in the third clear liquid and the second sludge.

5. The method for microbial maintenance and full-scale treatment of high-salt landfill leachate according to claim 4, characterized in that, In step 4, the third clear liquid is treated by the filter system. The suspended solids (SS) in the third clear liquid are removed by nitrification and denitrification, and COD is removed by oxidation, resulting in the fourth clear liquid and the third type of sludge. After the fourth clear liquid meets the standards, it is discharged into the qualified water discharge system.

6. The method for microbial maintenance and full-scale treatment of high-salt landfill leachate according to claim 5, characterized in that, In step 4, the fourth clear liquid is treated with activated carbon by an activated carbon system. The activated carbon further adsorbs the recalcitrant organic matter in the fourth clear liquid to obtain the fifth clear liquid, which is discharged in compliance with standards.

7. The method for microbial maintenance and full-scale treatment of high-salt landfill leachate according to claim 1, characterized in that, The sludge obtained in step 3 is dewatered through a sludge dewatering system. Specifically, sludge and water are separated by filter cloth to obtain the fourth type of sludge and the sixth type of clear liquid. The fourth type of sludge is disposed of in a sanitary landfill, and the sixth type of clear liquid is reinjected into the sedimentation system for further processing.

8. The method for microbial maintenance and full-scale treatment of high-salt landfill leachate according to claim 1, characterized in that, In step 2, the desalination and nitrification liquor reflux flow rate, i.e., the first clear liquor volume, is calculated as follows: (Q 原水 ×m 原水盐浓度 +R 脱盐回流水 ×m 脱盐后盐浓度 ) / (Q 原水 +R 脱盐回流水 ×Q 原水 )=m 控制盐浓度 Q 原水 ---AO system raw water inflow, m 3 / h; m 原水盐浓度 ---Initial influent salt ion concentration, mg / L; R 脱盐回流水 ---Return ratio of wastewater with low salt ion concentration after desalination; m 脱盐后盐浓度 ---Concentration of salt ions in low-ion-concentration wastewater after desalination, mg / L; m 控制盐浓度 ---The salt ion concentration that needs to be controlled in the AO biochemical system, in mg / L.

9. The method for microbial maintenance and full-scale treatment of high-salt landfill leachate according to claim 1, characterized in that, The first concentrated liquid volume is calculated in step 2 as follows: 20%=Q 浓液 / Q 清液 Q 浓液 =20%×Q 清液 Q 浓液 ---Concentrated solution permeate, m 3 / h; Q 清液 ---Clear liquid production rate, m 3 / h.

10. The method for microbial maintenance and full-scale treatment of high-salt landfill leachate according to claim 1, characterized in that, The sludge return flow rate is calculated as follows: Q 污泥 =100%×Q 原水 Q 污水 ---Raw water inflow, m 3 / h; Q 污泥 ---Sludge return flow rate, m 3 / h.

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