Diversion treatment system and diversion treatment method for leachate of household garbage incineration plant

Abstract

The invention provides a domestic waste incineration plant leachate split-flow treatment system and a split-flow treatment method.The system comprises a filter, a first-stage pH adjusting pond, an adsorption pond, a primary sedimentation pond, a reaction pond and a clarification pond which are sequentially connected, and the clarification pond is connected with an anaerobic reactor and a second-stage pH adjusting pond through pipelines; the anaerobic reactor is sequentially connected with the front aerobic MBBR tank, the front anoxic FBBR tank, the rear aerobic MBBR tank, the rear anoxic FBBR tank, the micro-aerobic MBBR tank, the secondary sedimentation tank and the efficient sedimentation tank, the secondary pH regulating tank is sequentially connected with the deamination tower and the buffer tank through pipelines, and the buffer tank is respectively connected with the front anoxic FBBR tank and the rear anoxic FBBR tank through pipelines. According to the split-flow treatment system for the leachate of the household garbage incineration plant, part of the leachate enters the anaerobic reactor after residual sludge adsorption and chemical heavy metal removal clarification, and pollutants such as COD (Chemical Oxygen Demand), ammonia nitrogen and total nitrogen are removed through sludge-film blending biochemical nitrogen and carbon removal.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment, and in particular relates to a system and method for diverting leachate from a municipal solid waste incineration plant. Background Technology

[0002] With the acceleration of urbanization, the amount of municipal solid waste incinerated in my country has been increasing year by year. In 2024, the domestic waste incineration design capacity reached 388 million tons / year. Leachate from municipal solid waste incineration plants is produced by short-term composting of municipal solid waste in waste storage pits before incineration. The production of leachate from incineration plants accounts for about 10-30% of the waste treated. Both landfill leachate and wastewater from liquor enterprises are high-concentration organic wastewater with extremely high COD and BOD. Landfill leachate has a high concentration of easily biodegradable volatile fatty acids, which are easily utilized by denitrifying bacteria in activated sludge for denitrification.

[0003] Currently, the main technologies for treating leachate from municipal solid waste incineration plants include "pretreatment + MBR + membrane deep treatment," "pretreatment + two-stage DTRO," and "pretreatment + advanced oxidation + biochemical deep treatment." For example, Chinese invention patent CN114702196A discloses a multi-stage AO treatment process for landfill leachate, in which the leachate undergoes hydrolysis acidification + biological contact oxidation and MBR membrane separation to remove recalcitrant pollutants. Chinese invention patent CN115626711A discloses an integrated biochemical treatment process system and method for landfill leachate based on MABR, which treats landfill leachate through UBF anaerobic reaction + multi-stage MABR technology.

[0004] Landfill leachate is characterized by high salt and high toxicity. High salt concentrations have a significant inhibitory effect on microorganisms, while heavy metal salts are often highly toxic and can interact with enzymes or other key molecules within cells, thereby disrupting normal cell function and reducing biological activity. Therefore, conventional activated sludge processes cannot effectively remove pollutants. Membrane processes such as reverse osmosis produce 10-30% concentrate, and the treatment cost of concentrate is very high, which leads to a significant increase in the treatment cost of landfill leachate. Summary of the Invention

[0005] In view of this, the present invention aims to overcome the defects in the prior art and proposes a leachate diversion and treatment system and method for municipal solid waste incineration plants.

[0006] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0007] A leachate diversion and treatment system for a municipal solid waste incineration plant includes a filter, a primary pH adjustment tank, an adsorption tank, a primary sedimentation tank, a reaction tank, and a clarification tank connected in sequence. The clarification tank is connected to an anaerobic reactor and a secondary pH adjustment tank via pipelines. The anaerobic reactor is connected in sequence to a pre-aerobic MBBR tank, a pre-anoxic FBBR tank, a post-aerobic MBBR tank, a post-anoxic FBBR tank, a micro-aerobic MBBR tank, a secondary sedimentation tank, and a high-efficiency sedimentation tank. The secondary pH adjustment tank is connected in sequence to a deammoniation tower and a buffer tank via pipelines. The buffer tank is connected to the pre-anoxic FBBR tank and the post-anoxic FBBR tank via pipelines.

[0008] Furthermore, the secondary sedimentation tank, anaerobic reactor, and high-efficiency sedimentation tank are respectively connected to the adsorption tank via pipelines.

[0009] The graded treatment method using the aforementioned municipal solid waste incineration plant leachate diversion and treatment system includes the following steps:

[0010] (1) The landfill leachate enters the filter for filtration, and then is sequentially transported to the primary pH adjustment tank, primary sedimentation tank, reaction tank and clarification tank;

[0011] (2) The effluent from the clarifier is diverted to the anaerobic reactor and the secondary pH adjustment tank. The effluent from the anaerobic reactor is sequentially transported to the pre-aerobic MBBR tank, the pre-anoxic FBBR tank, the post-aerobic MBBR tank, the post-anoxic FBBR tank, the micro-aerobic MBBR tank, the secondary sedimentation tank and the high-efficiency sedimentation tank. The effluent from the secondary pH adjustment tank is sequentially transported to the deammoniation tower and the buffer tank.

[0012] (3) The effluent from the buffer tank is diverted to the pre-anoxic FBBR tank and connected to the post-anoxic FBBR tank; the excess sludge from the secondary sedimentation tank, anaerobic reactor and high-efficiency sedimentation tank is transported to the adsorption tank.

[0013] Furthermore, the outlet of the clarifier in step (2) is equipped with a COD detector, a total nitrogen detector and an online flow meter; the pipeline between the clarifier and the anaerobic reactor and the pipeline between the clarifier and the secondary pH adjustment tank in step (2) are equipped with flow meters and solenoid valves.

[0014] Furthermore, in step (2), a COD analyzer, a total nitrogen analyzer, and an online flow meter are installed on the pipeline between the pre-aerobic MBBR tank and the pre-anoxic FBBR tank; in step (2), a COD analyzer, a total nitrogen analyzer, and an online flow meter are installed on the pipeline between the post-aerobic MBBR tank and the post-anoxic FBBR tank; and in step (2), a flow meter and a metering pump are installed on the pipeline between the buffer tank and the pre-anoxic FBBR tank, and on the pipeline between the buffer tank and the post-anoxic FBBR tank.

[0015] Furthermore, the diversion step in step (2) is shown in the following formula:

[0016] Q1*(C TN1 -C TN0 )+Q2*((1-f)*C TN1 -C TN0 )=S*Q2*C cod / K Formula (I)

[0017] R = Q1 / Q2 = C cod *SK*((1-f)*C TN1 -C TN0 )) / K(C TN1 -C TN0 Formula (II)

[0018] Where R is the split ratio; K is the amount of COD consumed per unit of TN removed, K = 6-12 gCOD / gTN; Q1 is the flow rate entering the anaerobic reactor, m 3 / h; Q2 is the flow rate entering the secondary pH adjustment tank, m 3 / h;C TN1 The total nitrogen concentration in the effluent from the clarifier is mg / L; C TN0 The expected total nitrogen concentration in the effluent, mg / L; C cod denoted as COD concentration in the effluent of the clarifier (mg / L); f is the total nitrogen removal rate of the ammonia removal tower (f = 0.7-0.8); and S is the safety factor (S = 0.9-1.0).

[0019] Furthermore, in step (3), the flow rates Q3 and Q4 diverted from the buffer tank to the pre-anoxic FBBR tank and the post-anoxic FBBR tank in the diversion step are calculated as follows:

[0020] Q3=(K*(Q1+Q5-Q6)*C TN3 -(Q1+Q5-Q6)*C cod2 ) / C cod1 Formula (III)

[0021] Q4 = (K * (Q1 + Q5 - Q6 + Q3) * C) TN4 -(Q1+Q5-Q6+Q3)*C cod3 ) / C cod1 Formula (Ⅳ)

[0022] Where Q5 is the effluent flow rate of the pre-aerobic MBBR tank, in m 3 / h;C TN3 Q1 is the total nitrogen concentration in the effluent from the pre-aerobic MBBR tank, mg / L; Q2 is the sludge return flow rate in the secondary sedimentation tank, m³ / h. 3 / h; Q6 is the sludge discharge rate of the anaerobic reactor, m3 / h;C TN4 The total nitrogen concentration in the effluent from the post-aerobic MBBR tank is mg / L; C cod1 The COD value of the buffer tank is in mg / L; C cod2 The COD value of the effluent from the pre-aerobic MBBR tank is in mg / L; C cod3 The value of COD in the effluent from the post-aerobic MBBR tank is in mg / L.

[0023] Furthermore, the filter screen in step (1) has a mesh size of 0.2 mm; the pH value of the solution in the primary pH adjustment tank in step (1) is 7-8, and the stirring time is 5-10 minutes; the pH value of the solution in the secondary pH adjustment tank in step (2) is 9-10, and the stirring time is 5-10 minutes.

[0024] Furthermore, in step (1), sodium hydroxide, sodium carbonate, and sodium sulfide are added to the reaction tank. The dosage of sodium hydroxide is 100-500 mg / L, the dosage of sodium carbonate is 100-500 mg / L, and the dosage of sodium sulfide is 10-100 mg / L. In step (1), coagulant and flocculant are added to the clarification tank. The dosage of coagulant is 10-100 mg / L, and the dosage of flocculant is 0.5-3 mg / L. The coagulant is at least one of polyferric sulfate, polyaluminum chloride, or ferric chloride, and the flocculant is polyacrylamide.

[0025] Further, the retention time of the adsorption tank in step (1) is 0.5-2 hours; the retention time of the primary sedimentation tank in step (1) is 1.5-3 hours; the reaction time of the reaction tank in step (1) is 5-10 minutes; the clarification time of the clarification tank in step (1) is 10-30 minutes; the sludge concentration of the pre-aerobic MBBR tank in step (2) is 8000-15000 mg / L, with an aeration device at the bottom, a dissolved oxygen concentration of 2.0-6.0 mg / L, an MBBR filling rate of 50-70%, and a retention time of 24-72 hours; the sludge concentration of the pre-anoxic FBBR tank in step (2) is 8000-15000 mg / L, a dissolved oxygen concentration of 0-0.5 mg / L, an FBBR filling rate of 40-60%, and a retention time of 24-72 hours; the post-aerobic... The sludge concentration in the MBBR tank is 8000-15000 mg / L, with an aeration device at the bottom, a dissolved oxygen concentration of 2.0-6.0 mg / L, an MBBR filling rate of 40-60%, and a retention time of 12-24 h; the sludge concentration in the post-anoxic FBBR tank in step (2) is 8000-15000 mg / L, a dissolved oxygen concentration of 0-0.5 mg / L, an FBBR filling rate of 50-70%, and a retention time of 12-24 h; the sludge concentration in the micro-aerobic MBBR tank in step (2) is 8000-15000 mg / L, a dissolved oxygen concentration of 0.5-1.0 mg / L, an MBBR filling rate of 40-60%, and a retention time of 12-24 h; the retention time in the secondary sedimentation tank in step (2) is 2-4 h; and the retention time in the high-efficiency sedimentation tank in step (2) is 10-30 minutes.

[0026] Leachate from municipal solid waste incineration plants first undergoes filtration to remove most particulate matter. It then enters a primary pH adjustment tank to adjust the pH to 7-8. After thorough mixing, it proceeds to an adsorption tank, where it mixes with residual sludge from the secondary sedimentation tank, anaerobic reactor, and high-efficiency sedimentation tank. The residual sludge adsorbs heavy metals, COD, and other pollutants from the leachate, while simultaneously diluting the pollutant concentration in the original solution to ensure stable operation of subsequent systems. The leachate then enters a primary sedimentation tank, where flocculants are added. The supernatant enters a reaction tank, where heavy metal removal agents are added to further remove magnesium, copper, lead, chromium, nickel, and other metallic metals from the leachate. After the leachate undergoes a complete reaction, it enters a clarifier. In the clarifier, coagulants and flocculants are added. A portion of the supernatant enters an anaerobic reactor to remove most of the COD and simultaneously degrade large organic molecules into smaller ones. This supernatant then sequentially enters a pre-aerobic MBBR tank, a pre-anoxic FBBR tank, a post-aerobic MBBR tank, a post-anoxic FBBR tank, and a microaerobic MBBR tank to remove COD, ammonia nitrogen, and total nitrogen. The remaining portion enters a secondary pH adjustment tank to adjust the pH to 9-10 before entering a deammoniation tower to remove most of the ammonia nitrogen. This deammoniation then enters the pre-anoxic FBBR tank and the post-anoxic FBBR tank. Finally, suspended solids are removed through a secondary sedimentation tank and a high-efficiency sedimentation tank.

[0027] The leachate diversion and treatment system of a municipal solid waste incineration plant is as follows:

[0028] Filter: The landfill leachate is filtered through a filter with a filtration accuracy of 0.2mm to remove large particles and some suspended solids from the landfill leachate.

[0029] Primary pH Adjustment Tank: The filtered leachate is transported to the primary pH adjustment tank, and alkaline substances such as sodium hydroxide are added to adjust the pH value to between 7 and 8. The mixture is stirred for 5-10 minutes.

[0030] Adsorption tank: The excess sludge from the secondary sedimentation tank, anaerobic reactor, and high-efficiency sedimentation tank enters the adsorption tank to remove some heavy metals and COD pollutants from the landfill leachate. The retention time in the adsorption tank is 0.5-2 hours. The excess sludge in the adsorption tank adsorbs heavy metals through bioflocculation, the adsorption of extracellular polymers secreted by bacteria, and the adsorption-chelation of bacterial decomposition products, reducing the impact of heavy metals and other toxic substances on the subsequent activated sludge. At the same time, the excess activated sludge adsorbs pollutants such as COD in the raw liquid, reducing the treatment load of subsequent processes and improving the stability of the biological system.

[0031] Primary sedimentation tank: The retention time is 1.5-3 hours to achieve solid-liquid separation.

[0032] Reaction tank: Sodium hydroxide, sodium carbonate, sodium sulfide, and other chemical reagents are added to remove metal ions. Under alkaline conditions, Mg... 2+ Fe 3+ Cu2+ Plasma and OH - The mixture combines to form a precipitate, and the reaction time is 5-10 minutes.

[0033] Clarification tank: Add coagulants such as polyferric sulfate, polyaluminum chloride or ferric chloride, mix evenly, and then add flocculants such as polyacrylamide. Let it settle and clarify for 10-30 minutes to achieve solid-liquid separation.

[0034] Anaerobic reactor: In an anaerobic environment, landfill leachate is decomposed into small molecules by anaerobic microorganisms, thereby reducing COD and BOD.

[0035] Pre-aerobic MBBR tank: sludge concentration is 8000-15000 mg / L, aeration device is installed at the bottom, dissolved oxygen concentration is 2.0-6.0 mg / L, MBBR filling rate is 50-70%, and retention time is 24-72 h. This process converts ammonia nitrogen into nitrate nitrogen through nitrification by nitrifying bacteria, further removing ammonia nitrogen from landfill leachate.

[0036] Pre-anoxic FBBR tank: sludge concentration is 8000-15000 mg / L, dissolved oxygen concentration is 0-0.5 mg / L, FBBR filling rate is 40-60%, and retention time is 24-72 h. In this process, denitrifying bacteria convert nitrate nitrogen into nitrogen gas, further removing total nitrogen from landfill leachate.

[0037] Post-aerobic MBBR tank: sludge concentration is 8000-15000 mg / L, aeration device is installed at the bottom, dissolved oxygen concentration is 2.0-6.0 mg / L, MBBR filling rate is 40-60%, and retention time is 12-24 h. This process converts ammonia nitrogen into nitrate nitrogen through nitrification by nitrifying bacteria, further removing ammonia nitrogen from landfill leachate.

[0038] Post-anoxic FBBR tank: sludge concentration is 8000-15000 mg / L, dissolved oxygen concentration is 0-0.5 mg / L, FBBR filling rate is 50-70%, and retention time is 12-24 h. In this process, denitrifying bacteria convert nitrate nitrogen into nitrogen gas, further removing total nitrogen from landfill leachate.

[0039] Micro-aerobic MBBR tank: sludge concentration is 8000-15000 mg / L, dissolved oxygen concentration is 0.5-1.0 mg / L, MBBR filling rate is 40-60%, and retention time is 12-24 h. This process converts ammonia nitrogen into nitrate nitrogen through nitrification by nitrifying bacteria, while denitrifying bacteria in the MBBR packing convert nitrate nitrogen into nitrogen gas, achieving simultaneous nitrification and denitrification, and reducing the concentration of COD, ammonia nitrogen and total nitrogen in landfill leachate.

[0040] Secondary pH adjustment tank of the diversion section: Add alkaline substances such as sodium hydroxide to adjust the pH value of the landfill leachate to 9-10, and stir for 5-10 minutes.

[0041] Ammonia removal tower: Gas is passed into the water to ensure full contact between the gas and liquid phases. This allows dissolved free ammonia in the water to cross the gas-liquid interface and transfer to the gas phase, thereby removing ammonia nitrogen. After treatment in the ammonia removal tower, the water enters a buffer tank. The buffer tank is equipped with an overflow outlet, which is connected to the anaerobic reactor.

[0042] Secondary sedimentation tank: The retention time is 2-4 hours, which further removes suspended solids from the landfill leachate.

[0043] High-efficiency sedimentation tank: The retention time is 10-30 minutes, which further removes suspended solids from landfill leachate.

[0044] Compared with the prior art, the present invention has the following advantages:

[0045] The leachate diversion and treatment system for municipal solid waste incineration plants described in this invention, after adsorption of excess sludge and chemical clarification, partially enters the anaerobic reactor, where it undergoes biochemical denitrification and carbon removal to remove pollutants such as COD, ammonia nitrogen, and total nitrogen. The remaining portion, after pH adjustment, enters the deammoniation tower, where most of the ammonia nitrogen is removed, and then it enters the pre-anoxic FBBR and post-anoxic FBBR tanks respectively, fully utilizing the organic matter in the leachate for denitrification and carbon removal. The leachate diversion and treatment method monitors parameters such as the total nitrogen concentration in the aerobic MBBR tank effluent in real time, and calculates the leachate diversion flow rate based on the COD value of the clarifier effluent and the denitrification capacity of the leachate. This allows for the rational allocation of leachate for diversion and treatment, reducing the load on equipment such as the anaerobic reactor and deammoniation tower. It also fully utilizes the organic matter in the leachate to achieve zero carbon source addition for the biological system's denitrification and nitrogen removal, reducing treatment costs and demonstrating significant application value. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of the leachate diversion and treatment system of a municipal solid waste incineration plant as described in an embodiment of the present invention. Detailed Implementation

[0047] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art. Unless otherwise specified, the experimental reagents used in the following embodiments are conventional biochemical reagents; and the experimental methods described are conventional methods.

[0048] The present invention will be described in detail below with reference to embodiments.

[0049] Example 1

[0050] A waste incineration plant in Tianjin produces 100 tons of leachate per day. The initial pH of the raw leachate is 5.26, the COD concentration is 58,946 mg / L, the BOD concentration is 31,763 mg / L, the total phosphorus concentration is 35 mg / L, the total nitrogen concentration is 1,982 mg / L, the ammonia nitrogen concentration is 1,816 mg / L, and the suspended solids concentration is 4,760 mg / L.

[0051] The leachate from the municipal solid waste incineration plant first passes through a basket filter (filtration accuracy of 0.2 mm) to filter out most particulate matter. Then it enters the primary pH adjustment tank, where sodium hydroxide is added to adjust the pH of the leachate to 7. After stirring and mixing, it enters the adsorption tank, where the retention time is 1 hour. The flow rate of residual sludge in the secondary sedimentation tank, high-efficiency sedimentation tank, and anaerobic reactor is 20 tons / day. Afterward, it enters the primary sedimentation tank, where a prepared cationic polyacrylamide flocculant with a mass concentration of 3‰ is added at a dosage of 0.5 ml / L. After sedimentation for 2 hours, the supernatant enters the reaction tank, where sodium hydroxide, sodium carbonate, and sodium sulfide are added at a dosage of 200 mg / L, 100 mg / L, and 20 mg / L, respectively. The mixture is stirred and mixed for 10 minutes to remove most of the calcium, magnesium, chromium, copper, iron, and other metal ions from the leachate. After sufficient reaction, the mixture enters a clarification tank. A 12% polyaluminum chloride solution (30 mg / L) is added as a coagulant. After thorough mixing, a 3‰ cationic polyacrylamide flocculant (1 ml / L) is added. After stirring and mixing for 15 minutes, the mixture is clarified and the solid and liquid are separated. The COD of the supernatant is 44,000 mg / L, and the total nitrogen is 1,600 mg / L.

[0052] A portion of the effluent from the clarifier enters the anaerobic reactor, which is an upflow UASB reactor with a hydraulic retention time of 16 days and a design volumetric loading rate of 3.5 kg COD / m³. 3 The sludge concentration is 30-40 g / L, the COD of the anaerobic reactor effluent is about 4000 mg / L, and the total nitrogen is about 1600 mg / L.

[0053] The effluent from the anaerobic reactor enters the pre-aerobic MBBR tank. The sludge concentration in the aerobic MBBR tank is 10000 mg / L, the dissolved oxygen concentration is 4 mg / L, the MBBR packing filling rate is 50%, the sludge return ratio in the secondary sedimentation tank is 100%, and the retention time is 72 h. After passing through the pre-aerobic MBBR tank, most of the COD and some ammonia nitrogen in the water are removed. The ammonia nitrogen loading is 0.05 kg NH3-N / (kg MLSS·d). The COD concentration of the effluent from the pre-aerobic MBBR tank is approximately 400 mg / L, and the total nitrogen concentration is approximately 750 mg / L.

[0054] The effluent from the pre-aerobic MBBR tank enters the pre-anoxic FBBR tank. The sludge concentration in the pre-anoxic FBBR tank is 10000 mg / L, the dissolved oxygen concentration is less than 0.5 mg / L, the FBBR filling rate is 50%, and the retention time is 48 h. In this process, denitrifying bacteria convert nitrate nitrogen into nitrogen gas, further removing total nitrogen from the landfill leachate. The total nitrogen load is 0.03 kgTN / (kgMLSS·d), the effluent COD concentration is about 260 mg / L, and the total nitrogen concentration is about 120 mg / L.

[0055] The effluent from the pre-anoxic FBBR tank enters the post-aerobic MBBR tank. The sludge concentration in the post-aerobic MBBR tank is 10000 mg / L, the dissolved oxygen concentration is 4 mg / L, the MBBR filling rate is 50%, and the retention time is 12 hours. In this process, ammonia nitrogen is converted into nitrate nitrogen through nitrification by nitrifying bacteria. The effluent COD concentration is about 200 mg / L, and the total nitrogen concentration is about 120 mg / L.

[0056] The effluent from the pre-aerobic MBBR tank enters the post-anoxic FBBR tank. The sludge concentration is 10,000 mg / L, the dissolved oxygen concentration is less than 0.5 mg / L, the FBBR filling rate is 50%, and the retention time is 12 hours. The COD concentration of the effluent from the post-anoxic MBBR tank is about 150 mg / L, and the total nitrogen concentration is about 80 mg / L.

[0057] The effluent from the anoxic FBBR tank enters the micro-aerobic MBBR tank, with a sludge concentration of 10,000 mg / L, a dissolved oxygen concentration of 0.8 mg / L, an MBBR filling rate of 50%, and a retention time of 12 hours. The effluent from the micro-aerobic MBBR tank then proceeds to a secondary sedimentation tank and a high-efficiency sedimentation tank to remove suspended solids, meeting the emission standards stipulated in the "Standard for Pollution Control of Municipal Solid Waste Incineration" (GB18485-2014). The sediment from the primary sedimentation tank and clarifier is dewatered by a plate and frame dewatering machine before being transported to the incinerator for incineration.

[0058] Sodium hydroxide was added to the secondary pH adjustment tank to adjust the pH of the landfill leachate to about 9.5. After stirring for 10 minutes, the leachate was introduced into the deammoniation tower to remove most of the ammonia nitrogen. Gas was introduced into the water to ensure full contact between the gas and liquid phases, allowing the free ammonia dissolved in the water to pass through the gas-liquid interface and transfer to the gas phase, thereby removing ammonia nitrogen. The gas-liquid ratio of the deammoniation tower was 2000:1, the air temperature was 40℃, the stripping time was 6 hours, and the total nitrogen in the effluent was 450 mg / L.

[0059] The main indicators of leachate from municipal solid waste incineration plants after treatment using this method (meeting the direct discharge standards) are shown in Table 1.

[0060] Table 1 Key Indicators

[0061] index COD BOD TN ammonia nitrogen TP SS Color Value (mg / L) 84.6 12.5 36.4 19.7 1.24 7 10 index Total copper Total Zinc Total Mercury Total Chromium Total cadmium Total arsenic Total lead Value (μg / L) 122 562 0.74 78.6 6.20 36.9 26.4

[0062] Landfill leachate diversion and treatment methods:

[0063] The effluent from the clarifier has a COD of approximately 44,000 mg / L and a total nitrogen of 1,600 mg / L. The ammonia nitrogen removal rate of the deammoniation tower is 70%, and the COD removal rate of the anaerobic reactor is 90%. The target total nitrogen value for the effluent is 10 mg / L. The denitrification capacity of the landfill leachate is 8 gCOD / gTN. With a safety factor of 0.9, the calculated R value is 2.8, which means that Q2 is 26.3 tons / day, Q1 is 73.7 tons / day, Q3 flow rate is 22.4 tons / day, and Q4 flow rate is 3.9 tons / day.

[0064] Experiment on the denitrification capacity of landfill leachate: 50L of activated sludge from the end of the micro-oxygen MBBR tank was placed in the experimental container. The stirrer was turned on and stirred slowly to keep the sludge in a uniform mixing state. Dissolved oxygen was measured using a portable dissolved oxygen meter. After the dissolved oxygen concentration was below 0.5mg / L, the mixed liquid was taken to test COD and TN.

[0065] Add nitrate nitrogen standard solution (calculated as N) to the experimental container at a concentration of 50 mg / L. Add landfill leachate to the container according to a C / N ratio of 12 and begin the experiment. After stirring and reacting for 4 hours, take samples to detect COD and TN. Calculate Kexperiment = (CL + CN). cod front-C cod (after) / (C) TN front-C TN (After). Before the experiment, the total nitrogen value was 85 mg / L and the COD value was 680 mg / L. After the experiment, the total nitrogen value was 35 mg / L and the COD value was 280 mg / L. The calculated K value was 8 g COD / g TN.

[0066] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A leachate diversion and treatment system for municipal solid waste incineration plants, characterized in that: The system includes a filter, a primary pH adjustment tank, an adsorption tank, a primary sedimentation tank, a reaction tank, and a clarification tank connected in sequence. The clarification tank is connected to an anaerobic reactor and a secondary pH adjustment tank via pipelines. The anaerobic reactor is connected in sequence to a pre-aerobic MBBR tank, a pre-anoxic FBBR tank, a post-aerobic MBBR tank, a post-anoxic FBBR tank, a micro-aerobic MBBR tank, a secondary sedimentation tank, and a high-efficiency sedimentation tank. The secondary pH adjustment tank is connected in sequence to a deammoniation tower and a buffer tank via pipelines. The buffer tank is connected to the pre-anoxic FBBR tank and the post-anoxic FBBR tank via pipelines.

2. The leachate diversion and treatment system for municipal solid waste incineration plants according to claim 1, characterized in that: The secondary sedimentation tank, anaerobic reactor, and high-efficiency sedimentation tank are connected to the adsorption tank via pipelines.

3. A method for diverting leachate from a municipal solid waste incineration plant using the leachate diversion and treatment system described in claim 1 or 2, characterized in that: Includes the following steps: (1) The landfill leachate enters the filter for filtration, and then is sequentially transported to the primary pH adjustment tank, primary sedimentation tank, reaction tank and clarification tank; (2) The effluent from the clarifier is diverted to the anaerobic reactor and the secondary pH adjustment tank. The effluent from the anaerobic reactor is sequentially transported to the pre-aerobic MBBR tank, the pre-anoxic FBBR tank, the post-aerobic MBBR tank, the post-anoxic FBBR tank, the micro-aerobic MBBR tank, the secondary sedimentation tank and the high-efficiency sedimentation tank. The effluent from the secondary pH adjustment tank is sequentially transported to the deammoniation tower and the buffer tank. (3) The effluent from the buffer tank is diverted to the pre-anoxic FBBR tank and connected to the post-anoxic FBBR tank; the excess sludge from the secondary sedimentation tank, anaerobic reactor and high-efficiency sedimentation tank is transported to the adsorption tank.

4. The diversion processing method according to claim 3, characterized in that: The outlet of the clarifier in step (2) is equipped with a COD detector, a total nitrogen detector and an online flow meter; the pipeline between the clarifier and the anaerobic reactor and the pipeline between the clarifier and the secondary pH adjustment tank in step (2) are equipped with flow meters and solenoid valves.

5. The diversion processing method according to claim 3, characterized in that: In step (2), a COD analyzer, a total nitrogen analyzer, and an online flow meter are installed on the pipeline between the pre-aerobic MBBR tank and the pre-anoxic FBBR tank; in step (2), a COD analyzer, a total nitrogen analyzer, and an online flow meter are installed on the pipeline between the post-aerobic MBBR tank and the post-anoxic FBBR tank; in step (2), a flow meter and a metering pump are installed on the pipeline between the buffer tank and the pre-anoxic FBBR tank, and on the pipeline between the buffer tank and the post-anoxic FBBR tank.

6. The diversion processing method according to claim 5, characterized in that: The diversion step in step (2) is shown in the following formula: Q1*(C TN1 -C TN0 )+Q2*((1-f)*C TN1 -C TN0 )=S*Q2*C cod / K-type (I) R = Q1 / Q2 = C cod *S - K*((1 - f)*C TN1 -C TN0 )) / K(C TN1 -C TN0 ) Equation (Ⅱ) Where R is the split ratio; K is the amount of COD consumed per unit of TN removed, K = 6-12 gCOD / gTN; Q1 is the flow rate entering the anaerobic reactor, m 3 / h; Q2 is the flow rate entering the secondary pH adjustment tank, m 3 / h;C TN1 The total nitrogen concentration in the effluent from the clarifier is mg / L; C TN0 The expected total nitrogen concentration in the effluent, mg / L; C cod denoted as COD concentration in the effluent of the clarifier (mg / L); f is the total nitrogen removal rate of the ammonia removal tower (f = 0.7-0.8); and S is the safety factor (S = 0.9-1.0).

7. The graded processing method according to claim 5, characterized in that: The flow rates Q3 and Q4 diverted from the buffer tank to the pre-anoxic FBBR tank and the post-anoxic FBBR tank in step (3) are calculated as follows: Q3 = (K * (Q1 + Q5 - Q6) * C TN3 - (Q1 + Q5 - Q6) * C cod2 ) / C cod1 Equation (Ⅲ) Q4 = (K * (Q1 + Q5 - Q6 + Q3) * C TN4 - (Q1 + Q5 - Q6 + Q3) * C cod3 ) / C cod1 Equation (IV) Where Q5 is the effluent flow rate of the pre-aerobic MBBR tank, in m 3 / h;C TN3 Q1 is the total nitrogen concentration in the effluent from the pre-aerobic MBBR tank, mg / L; Q2 is the sludge return flow rate in the secondary sedimentation tank, m³ / h. 3 / h; Q6 is the sludge discharge rate of the anaerobic reactor, m 3 / h;C TN4 The total nitrogen concentration in the effluent from the post-aerobic MBBR tank is mg / L; C cod1 The COD value of the buffer tank is in mg / L; C cod2 The COD value of the effluent from the pre-aerobic MBBR tank is in mg / L; C cod3 The value of COD in the effluent from the post-aerobic MBBR tank is in mg / L.

8. The hierarchical processing method according to claim 3, characterized in that: The filter in step (1) has a mesh size of 0.2 mm; the solution in the primary pH adjustment tank in step (1) has a pH value of 7-8 and a stirring time of 5-10 minutes; the solution in the secondary pH adjustment tank in step (2) has a pH value of 9-10 and a stirring time of 5-10 minutes.

9. The hierarchical processing method according to claim 3, characterized in that: In step (1), sodium hydroxide, sodium carbonate, and sodium sulfide are added to the reaction tank. The dosage of sodium hydroxide is 100-500 mg / L, the dosage of sodium carbonate is 100-500 mg / L, and the dosage of sodium sulfide is 10-100 mg / L. In step (1), coagulant and flocculant are added to the clarification tank. The dosage of coagulant is 10-100 mg / L, and the dosage of flocculant is 0.5-3 mg / L. The coagulant is at least one of polyferric sulfate, polyaluminum chloride, or ferric chloride, and the flocculant is polyacrylamide.

10. The hierarchical processing method according to claim 3, characterized in that: The retention time in the adsorption tank in step (1) is 0.5-2 hours; the retention time in the primary sedimentation tank in step (1) is 1.5-3 hours; the reaction time in the reaction tank in step (1) is 5-10 minutes; the clarification time in the clarification tank in step (1) is 10-30 minutes; the sludge concentration in the pre-aerobic MBBR tank in step (2) is 8000-15000 mg / L, with an aeration device at the bottom, a dissolved oxygen concentration of 2.0-6.0 mg / L, an MBBR filling rate of 50-70%, and a retention time of 24-72 hours; the sludge concentration in the pre-anoxic FBBR tank in step (2) is 8000-15000 mg / L, a dissolved oxygen concentration of 0-0.5 mg / L, an FBBR filling rate of 40-60%, and a retention time of 24-72 hours; the post-aerobic MBBR tank in step (2) is... The sludge concentration in the BR tank is 8000-15000 mg / L, with an aeration device at the bottom, a dissolved oxygen concentration of 2.0-6.0 mg / L, an MBBR filling rate of 40-60%, and a retention time of 12-24 h; the sludge concentration in the post-anoxic FBBR tank in step (2) is 8000-15000 mg / L, a dissolved oxygen concentration of 0-0.5 mg / L, an FBBR filling rate of 50-70%, and a retention time of 12-24 h; the sludge concentration in the micro-aerobic MBBR tank in step (2) is 8000-15000 mg / L, a dissolved oxygen concentration of 0.5-1.0 mg / L, an MBBR filling rate of 40-60%, and a retention time of 12-24 h; the retention time in the secondary sedimentation tank in step (2) is 2-4 h; and the retention time in the high-efficiency sedimentation tank in step (2) is 10-30 minutes.

Images