A method for treating leachate from a waste incineration power plant

Abstract

The present invention belongs to the technical field of landfill leachate treatment, and specifically relates to a method for treating leachate from a waste incineration power plant. The treatment method includes preparation of a heavy metal stabilizer, mechanochemical ball milling treatment and SBR biological treatment. The method includes the following steps: (a) using water extraction treatment to remove soluble salts in fly ash to obtain a heavy metal stabilizer for the leachate; (b) mixing the heavy metal stabilizer obtained in (a) with the leachate from the waste incineration power plant for mechanochemical ball milling treatment. At this stage, more than 90% of the humic acid, fulvic acid and total phosphorus in the leachate can be quickly and effectively degraded within 1 hour, and some nitrogen compounds (ammonia nitrogen and total nitrogen) can be degraded, and heavy metals can be stabilized in a solid stabilizer. No sludge will be generated in this mechanical or chemical ball milling treatment stage; (c) using SBR biological treatment to treat the ball milled leachate produced in (b) to achieve standard discharge.

Description

Technical Field

[0001] The invention belongs to the technical field of mechanochemical treatment of leachate from a garbage incineration power plant, and in particular relates to a ball milling equipment material, operating parameters and a treatment method. Background Art

[0002] Mechanochemistry is one of the commonly used mature materials science technologies. In recent decades, it has been often used in the preparation of nanopowders. In the past two decades, it has been cited in the field of environmental engineering for the treatment of pollutants, such as the stabilization of heavy metals in soil and waste incineration fly ash, the degradation of dioxins in waste incineration fly ash, and the degradation of POPs. In the application of sewage treatment, the principle of mechanochemistry is to promote the destruction of pollutant structure through the energy transfer and chemical reaction of grinding balls and grinding aids in the process of converting mechanical energy into chemical energy. Because its reaction driving force is a chemical reaction converted from mechanical energy, compared with biological reactions and advanced oxidation technologies, it reduces the generation of sludge. Therefore, this technology is a novel, effective and very promising treatment technology for degrading pollutants.

[0003] Landfill leachate has long been a source of pollution that everyone pays attention to. There are thousands of patents related to leachate treatment technology, and countless related scientific research papers. The main principles include: biological treatment (combination of anaerobic, aerobic, anoxic and biological agents), advanced oxidation (Fenton; Fenton / UV; Fenton / O3; Fenton / biological treatment), membrane separation technology (ultrafiltration membrane, nanofiltration membrane, reverse osmosis membrane, membrane distillation, reverse osmosis / freeze concentration, reverse osmosis / high temperature treatment), catalytic reaction (photocatalysis, thermal catalysis, enzyme catalysis, electrocatalysis, catalytic oxidation), etc. In addition, the leachate from waste incineration power plants can be regarded as the leachate from the early stage of landfill, and its pollution level is also of great concern to everyone.

[0004] Chinese patent CN101357368B, a method for stabilizing heavy metals in garbage incineration ash, discloses a method for stabilizing heavy metals using the ball milling principle;

[0005] Taiwan Patent No. I349656, a method for stabilizing heavy metals in urban waste incineration ash and recycling ash, discloses a method for stabilizing heavy metals in fly ash using the ball milling principle and recycling the ball milled ash;

[0006] Chinese patent CN101407380B, a method for recycling fly ash from garbage incineration as cement material, discloses a method for stabilizing fly ash with heavy metals using the ball milling principle and recycling it as cement material;

[0007] Taiwan Patent No. I371437, a method for recycling fly ash from garbage incineration as cement material, discloses a method for stabilizing fly ash with heavy metals using the ball milling principle and recycling it as cement material;

[0008] Chinese patent CN106892676B, Humidity-controlled ceramics and their production method, discloses a method of stabilizing fly ash with heavy metals using the ball milling principle and reusing it as humidity-controlled ceramics;

[0009] Taiwan Patent No. I568702, Humidity Control Ceramics and Their Manufacturing Method, discloses a method of stabilizing heavy metal fly ash using the ball milling principle and reusing it as humidity control ceramics;

[0010] Taiwan Patent No. I716910, Ceramic Filter Membrane and Method for Recycling Waste Incineration Fly Ash to Make Ceramic Filter Membrane, discloses a method of using ball milling principle to stabilize heavy metal fly ash and reusing it as ceramic filter membrane;

[0011] Journal of Hunan Institute of Technology (Natural Science Edition), "Ultrasonic-assisted ball milling to degrade ammonia nitrogen in simulated landfill leachate" research publicly used ultrasound and ball milling to conduct experiments, and configured artificial simulated leachate containing ammonia nitrogen (ammonia nitrogen concentration of 100-5,000 mg / L) as the treatment object. The equipment and operating conditions include a cleaning tank ultrasonic generator (40-100W), a constant speed stirrer (speed 250-700rpm), a polytetrafluoroethylene stirring rod, a three-necked flask, an iron ball (Φ=1mm, 50-200g), pH (3-13), and a reaction time (30-280min).

[0012] At present, the mechanochemical principle is used to treat environmental pollutants, mainly waste incineration fly ash and biphenyl-type difficult-to-degrade pollutants. It has been proved that the heavy metals in the water-extracted fly ash can be stabilized by ball milling technology.

[0013] Although mechanochemistry is a very promising driving force for wastewater treatment reactions, the literature on its related research is still very limited. Considering the purified environment and a single pollutant to discuss the effectiveness of leachate treatment, once faced with the actual complex composition of leachate, the traction between various factors will not be close to the actual situation.

[0014] Therefore, how to use the actual leachate as the treated wastewater and comprehensively discuss the removal of the main pollutants in the leachate, such as heavy metals, organic matter (COD, BOD, humic acid and fulvic acid), nitrogen compounds (ammonia nitrogen and total nitrogen) and total phosphorus, is still an important and undeveloped research field. Summary of the invention

[0015] In view of the problems existing in the prior art, the present invention provides a method for treating leachate from a waste incineration power plant. Mechanochemical ball milling can efficiently degrade humic acid, fulvic acid and total phosphorus in the leachate without producing sludge, and can stabilize heavy metals in water-extracted fly ash. Combined with the SBR biological treatment method, the pollution problem of the leachate can be simplified and effectively treated.

[0016] To achieve the above object, the present invention provides the following technical solutions:

[0017] A method for treating leachate from a waste incineration power plant, comprising: preparation of a heavy metal stabilizer, mechanochemical ball milling and SBR biological treatment; the mechanochemical ball milling treatment method comprises ball milling equipment and materials, ball milling parameters, ball milling liquid and a heavy metal stabilizer; the ball milling equipment comprises a ball mill, a ball milling tank and grinding balls; the ball mill is a horizontal ball mill and a planetary ball mill; the ball milling tank is made of zirconium oxide, aluminum oxide and stainless steel, and the grinding balls are made of zirconium oxide, aluminum oxide and stainless steel; the ball milling parameters include a grinding ball particle size of 1 mm to 20 mm, a ratio of the two grinding balls of 1:1, a heavy metal stabilizer The weight ratio of the agent to the ball milling liquid is 0.025-0.2, the volume ratio of the ball milling liquid to the ball milling jar is 0.05-0.65, the volume ratio of the grinding slurry plus the grinding balls to the ball milling jar is 0.3-0.7, the rotation speed of the ball milling jar is 50-800rpm, and the ball milling treatment time is 0.1 hour-100 hours; the ball milling liquid is the leachate stock solution, the heavy metal stabilizer is the water-extracted fly ash, and the heavy metal stabilizer and the ball milling liquid are mixed in a weight ratio called a ball milling slurry; the water-extracted fly ash has a liquid-to-solid ratio of 3-50, a water extraction time of 1 minute-60 minutes, and a water extraction procedure of 1-5 times, and the solid is separated from the solid. The SBR procedure includes the aeration stage of the SBR reaction tank, in which the MLSS concentration in the tank is 2000mg / L-5000mg / L, the influent COD concentration is 500mg / L-2000mg / L, the aeration volume per liter of wastewater in the aeration stage of the reaction tank is maintained at 0.1-1.5 liters / minute, the aeration reaction time is 2-18 hours, and continuous mechanical stirring.

[0018] The preparation of the heavy metal stabilizer in the method of the present invention is mainly to reduce the soluble chloride salts that are not conducive to the stabilization of heavy metals and the structural strength of the subsequent fly ash recycling material. This preparation method mainly uses water extraction to remove water-soluble salts in fly ash, which is beneficial to the stabilization of heavy metals in the subsequent ball milling process and can shorten the time for ball milling to stabilize heavy metals. Therefore, the present invention uses the fly ash after water extraction as a heavy metal stabilizer in the leachate treatment process. The mechanochemical ball milling process in the method of the present invention is the first discovery that the chemical energy converted from the mechanical energy of ball milling can directly and effectively degrade humic acid, fulvic acid and total phosphorus in the leachate by more than 90% within 1 hour, as well as part of COD, BOD, ammonia nitrogen and total nitrogen, and can stabilize the heavy metals in the leachate in the solid water-extracted fly ash to achieve the purpose of removing heavy metals in the leachate; this ball milling process does not produce sludge. The SBR biological treatment process in the method of the present invention verifies that the pollutants in the leachate after the mechanochemical ball milling process can be effectively removed by biological treatment and can meet the discharge standards.

[0019] Leachate is a common problem faced by landfills and waste incineration power plants. The present invention uses mechanochemical methods for the first time to efficiently treat humic acid, fulvic acid and total phosphorus, and stabilize heavy metals in fly ash. The mechanochemical ball milling process does not produce sludge, which can effectively reduce the sludge output and heavy metal content of the entire treatment method. The subsequent combination with the SBR biological treatment method can achieve standard emissions.

[0020] The method of mechanochemical treatment technology of leachate from waste incineration power plants related to the present invention includes: A. Preparation of heavy metal stabilizer (water extraction process): using efficient and water-saving low liquid-to-solid ratio and multi-stage water extraction process to remove water-soluble chloride salts in fly ash, thereby improving the ability of fly ash to stabilize heavy metals and its reuse value; B. Mechanochemical ball milling process: efficiently decompose humic acid, fulvic acid and total phosphorus in leachate; remove heavy metals in leachate and stabilize them in water-extracted fly ash solids; degrade part of COD, BOD, ammonia nitrogen and total nitrogen; no sludge is produced in this stage; C. The leachate obtained in step B is introduced into the SBR biological treatment method. Since step B has removed the difficult-to-biodegrade humic acid, fulvic acid and heavy metals, the SBR biological treatment method can effectively treat the leachate to meet the discharge standards.

[0021] The method of the present invention utilizes SBR biological treatment technology to treat the leachate after the mechanochemical ball milling process. After the ball milling treatment, the humic acid and fulvic acid of the leachate are greatly reduced, and the heavy metals are also separated from the liquid. At this time, the leachate is suitable for treatment using a biological treatment method. SBR can effectively remove organic matter (COD and BOD), ammonia nitrogen and total nitrogen. By controlling the sludge concentration, aeration volume, aeration time and continuous mechanical stirring of the reaction tank, the leachate can be treated to meet the discharge standards.

[0022] According to the method of the present invention, a ball milling technology is provided which can efficiently and simultaneously solve the main problems in the treatment of leachate, and produce two benefits. One is that the high molecular weight humic acid and fulvic acid in the leachate are reduced in a short period of time and the heavy metals in the liquid are removed, which is beneficial to the subsequent biological treatment; the other is that no sludge is produced in this reaction stage, which is beneficial to the saving of sludge treatment costs.

[0023] The heavy metals in the leachate and fly ash are stabilized in the water-extracted fly ash. The water-extracted fly ash stabilized by ball milling can pass the TCLP heavy metal dissolution standard. Because the crystal structure of the fly ash after ball milling has reached amorphous, it can effectively reduce the temperature of the sintering material technology and reduce energy consumption; on the other hand, it can increase the production of cement CSH colloids, shorten the reaction time and increase the strength of the structure, making it suitable as a raw material for recycling technologies such as sintering material and cement additives.

[0024] The following is a more detailed description of each step of the method for treating leachate from a waste incineration power plant of the present invention.

[0025] A. Preparation steps of heavy metal stabilizer:

[0026] The heavy metal stabilizer preparation (water extraction procedure) step of the waste incineration power plant leachate treatment method of the present invention can use single-stage and multi-stage water extraction procedures. In terms of extraction theory, when the extractant dosage is the same, the effect of multi-stage extraction will be better than that of single-stage extraction. The solid-liquid ratio of the experimental single-stage extraction is 1:2, 1:5, 1:8, and 1:10. When the solid-liquid ratio is 1:8 and 1:10, the chloride concentration in the extracted aqueous solution is the lowest and similar, and the extraction time is 5 minutes. If it is a multi-stage extraction, the chloride concentration of the aqueous solution has stabilized after extraction for more than two times.

[0027] B. Mechanochemical Ball Milling Steps:

[0028] The mechanochemical ball milling step in the method for treating the leachate from the waste incineration power plant of the present invention can adopt a ball milling device, and the ball mill can be a horizontal ball mill; select a suitable ball milling jar with a volume of 5 liters and a diameter of 20 cm, and the ball milling jar is made of alumina; select the grinding ball material as zirconium oxide; select the grinding ball particle size of 5 mm and 15 mm, and the two grinding balls are prepared in a ratio of 1:1; select the solid-liquid ratio (weight ratio) of the leachate and the heavy metal stabilizer as 10:1, and fully mix them to form a ball milling slurry; the volume ratio of the grinding ball to the ball milling jar is 0.22; the volume ratio of the ball milling slurry to the ball milling jar is 0.34; select the volume ratio of the grinding ball plus the ball milling slurry to the grinding ball jar as 0.56; calculate the rotation speed of the ball milling jar to be 104 rpm; and determine the ball milling reaction time of 1-96 hours. However, the use of the above-mentioned ball milling equipment is only a preferred means for implementing the method of the present invention. According to the method of the present invention, no matter whether a ball mill, a planetary ball mill or other ball milling equipment is used, as long as the ball milling method is used, the leachate can be treated effectively.

[0029] In the mechanochemical method for treating the leachate from a waste incineration power plant of the present invention, the leachate used in the mechanochemical ball milling step is a raw liquid without any treatment.

[0030] In the method of treating the leachate of a waste incineration power plant by mechanochemical ball milling of the present invention, the heavy metal stabilizer used in the mechanochemical ball milling step is water-extracted fly ash.

[0031] According to the method of mechanochemical ball milling technology for treating leachate from a waste incineration power plant of the present invention, after the leachate is subjected to the ball milling process, the heavy metal concentration of the leachate is reduced to a level that meets the water quality standard (Class A) for sewage discharge into urban sewers, and the removal rates of lead, chromium, copper and zinc are 71.94%, 100%, 74.49% and 82.09% respectively, indicating that the ball milling process has a removal effect on heavy metals in the leachate. The heavy metals in the leachate are stabilized in the water-extracted fly ash due to the conversion of mechanical energy generated by ball milling into chemical energy, so that the leachate meets the water quality standard (Class A) for discharge into urban sewers; the heavy metals stabilized in the water-extracted fly ash are subjected to the toxic characteristic leaching procedure (TCLP) announced by USEPA, and their leaching concentration can also be lower than the leaching concentration limit value of toxic substances.

[0032] The mechanochemical ball milling in the method of the present invention can be divided into horizontal ball milling and planetary ball milling, and the operating ball milling parameters are described as follows:

[0033] 1. Horizontal ball milling:

[0034] The ball mill can be a horizontal ball mill; the ball mill jar is made of alumina, zirconia and stainless steel; the grinding balls are made of alumina and zirconia; the grinding balls are prepared with particle sizes of 5mm and 15mm, and the two grinding balls are prepared in a ratio of 1:1; the solid-liquid ratio (weight ratio) of the leachate and the heavy metal stabilizer is selected to be 5-30, and the full mixing is called ball mill slurry; the volume ratio of the grinding balls to the ball mill jar is 0.05-0.65; the volume ratio of the ball mill slurry to the ball mill jar is 0.05-0.65; the volume ratio of the ball mill slurry plus the grinding balls to the ball mill jar is 0.3-0.7; the ball mill sets the ball mill jar speed to 50-150rpm; the operating time is 0.1 hour-100 hours.

[0035] 2. Planetary ball mill:

[0036] The ball mill can use a planetary ball mill; the ball mill is made of zirconium oxide and stainless steel; the grinding balls are made of stainless steel and zirconium oxide; the grinding balls are prepared with a particle size of 1mm to 30mm, and two types of grinding balls are selected to prepare different ratios; the solid-liquid ratio (weight ratio) of the leachate and the heavy metal stabilizer is selected to be 5-30, and the full mixing is called ball mill slurry; the volume ratio of grinding balls to ball mill is 0.05-0.65; the volume ratio of ball mill slurry to ball mill is 0.05-0.65; the volume ratio of ball mill slurry plus grinding balls to ball mill is 0.3-0.7; the ball mill sets the ball mill speed to 50-800rpm; the running time is 0.1 hour to 30 hours, and during ball milling, it is necessary to stop the machine from time to time to open the tank to release gas and reduce the temperature.

[0037] 3. Solid-liquid separation steps:

[0038] In the method for treating the leachate of a waste incineration power plant of the present invention, the ball milled slurry after mechanochemical ball milling needs to be separated into solid and liquid, and any separation method can be used for the solid-liquid separation without limitation. The present invention uses high-pressure suction filtration, and the separated liquid enters the SBR biological treatment process, and the solid can pass the heavy metal TCLP dissolution test.

[0039] C. SBR biological treatment steps:

[0040] According to the method for treating the leachate of a waste incineration power plant of the present invention, the leachate can be treated by mechanochemical ball milling and then by SBR biological treatment to achieve standard discharge. For example, the leachate treated by mechanochemical ball milling can be mixed with domestic sewage to a COD concentration of 1000-2000 mg / L, and the MLSS concentration after taming in the SBR reaction tank is 2000 mg / L-4000 mg / L. The aeration volume per liter of wastewater in the aeration stage of the reaction tank is maintained at 0.1-1.5 liters / minute, the aeration reaction time is 2-18 hours, and mechanical stirring is continued, then the concentrations of COD and ammonia nitrogen can be treated to meet the discharge standards.

[0041] Beneficial Effects

[0042] Compared with the prior art, the present invention has the following beneficial effects: the mechanochemical ball milling stage enables more than 90% of humic acid, fulvic acid and total phosphorus to be removed within 1 hour, and part of organic matter, ammonia nitrogen and total nitrogen are degraded, and heavy metals leave the water body and are stabilized in the solid stabilizer (water-extracted fly ash), which is very beneficial to subsequent biological treatment, and no sludge is generated in this stage; the SBR stage enables COD, ammonia nitrogen and total phosphorus to meet the comprehensive sewage discharge standard (GB 8978-1996). BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0044] Figure 1 Flow chart of leachate treatment method for waste incineration plant;

[0045] Figure 2 Changes in chloride salt concentration in single-stage and multi-stage water extraction;

[0046] Figure 3 Concentration changes and removal rates of humic acid at different ball milling times;

[0047] Figure 4 Concentration changes and removal rates of fulvic acid at different ball milling times;

[0048] Figure 5 COD concentration changes and removal rates at different ball milling times;

[0049] Figure 6 Concentration changes and removal rates of BOD at different ball milling times;

[0050] Figure 7 Changes in the ratio of BOD / COD at different ball milling times;

[0051] Figure 8 Concentration changes and removal rates of total phosphorus at different ball milling times;

[0052] Fig. 9 Concentration changes and removal rates of ammonia nitrogen at different ball milling times;

[0053] Fig.10 Concentration changes and removal rates of total nitrogen at different ball milling times;

[0054] Fig.11 Changes in Pb concentration in leachate at different ball milling times;

[0055] Fig.12 Changes in Cd concentration in leachate at different ball milling times;

[0056] Fig.13 Changes in Cr concentration in leachate at different ball milling times;

[0057] Fig.14 Changes in Cu concentration in leachate at different ball milling times;

[0058] Fig.15 Changes in Zn concentration in leachate at different ball milling times;

[0059] Fig.16 Changes in COD concentration and removal rate during the complete experimental period;

[0060] Fig.17 Changes in COD removal rate under different aeration rates;

[0061] Fig.18 Changes in ammonia nitrogen concentration and removal rate during the complete experimental period;

[0062] Fig.19 The removal rate of ammonia nitrogen changes at different aeration rates. DETAILED DESCRIPTION

[0063] The present invention is further described in detail with the following examples, but the examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0064] Example 1

[0065] Water Extraction Procedure for Fly Ash from Waste-to-Energy Plants

[0066] Description of experimental conditions: This experiment is divided into two parts, single-stage extraction and multi-stage extraction. The single-stage extraction procedure is: Place fly ash and reagent water in a tank at a solid-liquid ratio of 1:2, 1:5, 1:8, 1:10 (weight ratio) each time, and use TCLP dissolution rotor to extract water for 5 minutes. After water extraction, let it stand for 20 minutes to obtain the upper layer liquid for chloride monitoring. The multi-stage extraction procedure is: Step 1 Place water and fly ash in a tank at a liquid-to-solid ratio of 5 (weight ratio) each time, Step 2 Use TCLP dissolution rotor to extract water for 5 minutes, Step 3 Let it stand for 20 minutes after water extraction to extract the upper layer liquid for chloride monitoring, Step 4 Collect the remaining solids for use, and repeat the above steps 1 to 4 for the second extraction, and repeat the above steps 1 to 4 for the third extraction, until the fifth extraction experiment is completed. The experimental results are as follows Figure 1 shown.

[0067] Experimental results:

[0068] Chloride salt removal by water extraction is an effective method. Figure 1 It can be found that when the solid-liquid ratio of a single-stage water extraction is above 1:8, the extractable chloride concentration in the water has reached a stable level. For multi-stage water extraction, the chloride concentration in the water has not changed much after the second water extraction and reaches a stable level after the third water extraction.

[0069] Example 2

[0070] Effect of mechanochemical ball milling on leachate quality

[0071] Experimental conditions: The experimental equipment is a horizontal ball mill. Take a 5-liter alumina ball mill jar. The liquid-to-solid ratio (weight ratio) of the leachate and heavy metal stabilizer (water-extracted fly ash) is 10:1. The particle size of the zirconium oxide grinding balls is 5mm and 15mm. The two grinding balls are prepared in a ratio of 1:1. The volume ratio of the grinding balls to the ball mill jar is 22%, the volume ratio of the ball mill slurry to the ball mill jar is 34%, and the ball mill is set to a ball mill jar speed of 104rpm; the running time is 1-96 hours, in order to explore the effect of mechanochemical energy on the leachate water quality under different ball milling times. The experimental results are as follows: Figure 2-14 shown.

[0072] Experimental results:

[0073] 1. Influence of organic matter: After humic acid and fulvic acid are ball-milled for 1 hour, the removal rate can reach more than 90%. Figure 2 and Figure 3 This result shows that the mechanochemical ball milling reaction has a rapid removal effect on higher molecular weight organic matter. Figure 4 COD concentration and removal rate changes and Figure 5 The data of BOD concentration and removal rate change show that COD removal rate increases with the increase of treatment time, while BOD removal rate decreases and then increases. This phenomenon is because humic acid and fulvic acid, which are difficult to biodegrade, are degraded into low-molecular organic compounds that are easily biodegraded, resulting in an increase in BOD concentration and a decrease in removal rate. As the ball milling time continues to increase, the removal rates of COD and BOD have the same increasing trend. The BOD / COD ratio also increases from 0.64 to 0.77, indicating that the treated leachate is more suitable for biological treatment. During the experiment, the ball milling must be suspended in time and the ball mill jar must be opened for exhaust. It is inferred that as the ball milling time increases, the organic matter in the ball mill jar is converted into carbon dioxide under the action of mechanical chemical energy.

[0074] 2. Impact of total phosphorus: Ball milling has a significant effect on the removal of total phosphorus. Figure 7 This indicates that the total phosphorus removal rate can reach over 90% after one hour of ball milling.

[0075] 3. Effect of ammonia nitrogen and total nitrogen: The treatment trends of mechanochemical ball milling on ammonia nitrogen and total nitrogen are roughly the same, and the removal rates increase with the increase of treatment time. Figure 8 and Fig. 9 During the experiment, the ball milling must be stopped at the right time and the ball mill jar must be opened to exhaust gas. The exhaust gas is colorless and odorless. It is inferred that as the ball mill time increases, the ammonia nitrogen and total nitrogen are converted into nitrogen gas under the action of mechanical chemical energy.

[0076] 4. Influence of heavy metal concentration in leachate: During the ball milling process, the concentration of Pb in the leachate increases first and then slowly decreases. This phenomenon is because the Pb in the fly ash is released into the liquid due to the reduction of particle size in the early stage of ball milling. Then, as the ball milling time increases, the Pb in the liquid slowly stabilizes in the solid state, and finally achieves the purpose of removing heavy metals in the leachate. Fig.10 As shown. Due to their own characteristics, other heavy metals Cd, Cr, Cu, and Zn in the leachate will not be released from the fly ash in the early stage of ball milling. They will increase with the increase of ball milling time and will eventually be stabilized in the solid fly ash. Therefore, the concentration of Cd, Cr, Cu, and Zn in the leachate will decrease with the increase of ball milling time, as shown. Figure 11-14 shown.

[0077] Example 3

[0078] Effect of SBR on the water quality of leachate after ball milling

[0079] Experimental conditions: The experiment was conducted according to the SBR standard treatment process. The reaction tank operating parameters included: the MLSS concentration in the tank was 3000mg / L-3200mg / L, the influent COD concentration was 1300-2200mg / L, the aeration volume per liter of sewage during the aeration stage was 0.1-1.5 liters / minute, the aeration reaction time was 12 hours, and mechanical stirring was added during aeration. The experimental results are as follows: Figure 15-18 shown.

[0080] Experimental results:

[0081] 1. Impact of COD: Fig.15 This is the data of the complete experimental stage. The cycle description in the figure is: 1-8 cycles in the first stage of cultivation (2 cycles per day), 9-12 cycles in the second stage of cultivation, 13-20 cycles in the third stage of cultivation, 21-31 cycles in the acclimatization stage, 32-39 cycles in the first stage of treatment (aeration volume is 0.27 liters / minute per liter of sewage), 40-47 cycles in the second stage of treatment (aeration volume is 0.34 liters / minute per liter of sewage), 48-65 cycles in the third stage of treatment (aeration volume is 0.4 liters / minute per liter of sewage). In the treatment stage, different aeration volumes have different treatment efficiencies. Fig.16 It can be seen from the experiments with different aeration rates that the removal rate increases with the increase of aeration rate, and the removal rate is highest when the aeration rate is 0.4 liters / minute per liter of sewage.

[0082] 2. Impact of ammonia nitrogen: Fig.17 These are the data for the complete experimental phase. The cycle descriptions in the figure are the same as those for COD. Fig.18 It shows that when the aeration volume reaches 0.34 liters / minute per liter of sewage, the removal rate of ammonia nitrogen can reach more than 95%; when the aeration volume reaches 0.27 liters / minute per liter of sewage, the removal rate of ammonia nitrogen can reach 67%-90%.

[0083] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for treating leachate from a waste incineration power plant, characterized in that: The following steps are involved: A. Preparation of heavy metal stabilizer; B. Mechanical chemical ball milling treatment; C. SBR biological treatment; Step A: Preparation of heavy metal stabilizer: solid fly ash obtained by removing water-soluble salts from fly ash from an incineration power plant by water extraction is used as a stabilizer for heavy metals in leachate; The mechanochemical ball milling treatment in step B is as follows: the heavy metal stabilizer prepared in step A is mixed with the original leachate solution according to a proportion, and a mechanochemical ball milling reaction is performed; Step C SBR biological treatment is: finally, the leachate after ball milling in step B is treated by SBR biological treatment process to remove organic matter and ammonia nitrogen; The heavy metal stabilizer in step A is the solid obtained by solid-liquid separation of fly ash after a water extraction process with a liquid-to-solid ratio of 3-50:1, a water extraction time of 1 minute to 60 minutes, and 1 to 5 water extractions; The mechanochemical ball milling treatment in step B specifically comprises the following steps: Step 1, using the leachate stock solution as the ball milling solution; Step 2, preparing a horizontal ball mill or a planetary ball mill as a ball mill; Step 3, prepare a ball mill made of zirconium oxide, aluminum oxide or stainless steel; Step 4: Prepare grinding balls made of zirconium oxide, aluminum oxide or stainless steel; Step 5, mixing the heavy metal stabilizer with the leachate stock solution of step 1, with a mixing weight ratio of 0.025-0.2, which is called ball mill slurry; Step 6, selecting the grinding ball particle size range of step 4 to be 1 mm to 20 mm; Step 7, select two grinding balls with different particle sizes in step 6, and the volume ratio thereof is 1:1; Step 8, selecting the two grinding balls with different particle sizes described in step 7 and the ball mill described in step 3, and configuring the volume ratio of the grinding balls to the ball mill to be 0.05-0.65; Step 9, mixing the ball mill slurry of step 5 with the grinding balls of step 7, the total volume of which is 0.3-0.7 of the volume of the ball mill jar of step 3; Step 10, placing the ball milling jar configured in step 9 into the ball mill in step 2 for ball milling, setting the ball milling jar speed to 50-800 rpm, and the operating time to 0.1 hour to 100 hours; Step 11: After the ball milling is completed in step 10, solid-liquid separation is performed, and the liquid obtained after separation is called ball milling leachate, and the solid is called ball milling fly ash; The step C SBR biological treatment specifically comprises the following steps: Step 12, introducing the ball milling leachate from step 11 into the SBR reaction tank, wherein the concentration of the domesticated MLSS in the tank is 2000 mg / L-5000 mg / L; The operating parameters of the SBR reaction tank in step 13 and step 12 include maintaining an aeration rate of 0.1-1.5 liters / minute per liter of wastewater during the aeration stage, continuous mechanical stirring during the reaction, and a reaction time of 2-18 hours.

2. A method for treating leachate from a waste incineration power plant according to claim 1, characterized in that: When selecting a horizontal ball mill: the material of the ball mill is alumina, zirconia and stainless steel; the material of the grinding ball is alumina and zirconia; the particle size of the grinding ball is 5mm and 15mm, and the ratio of the two grinding balls is 1:1; the solid-liquid ratio of the leachate and heavy metal stabilizer (heavy The volume ratio of the ball mill to the ball mill jar is 0.05-0.65; the volume ratio of the ball mill slurry to the ball mill jar is 0.05-0.65; the volume ratio of the ball mill slurry plus the grinding balls to the ball mill jar is 0.3-0.7; the ball mill sets the ball mill jar speed to 50-150rpm; the running time is 0.1 hour to 100 hours.

3. A method for treating leachate from a waste incineration power plant according to claim 1, characterized in that: When choosing a planetary ball mill: the ball mill is made of zirconium oxide and stainless steel; the grinding balls are made of stainless steel and zirconium oxide; the grinding balls are prepared with a particle size of 1mm to 30mm, and two types of grinding balls are selected with different ratios; the solid-liquid ratio (weight ratio) of the leachate and the heavy metal stabilizer is selected to be 5-30, and the full mixing is called ball mill slurry; the volume ratio of the grinding balls to the ball mill is 0.05-0.65; the volume ratio of the ball mill slurry to the ball mill is 0.05-0.65; the volume ratio of the ball mill slurry plus the grinding balls to the ball mill is 0.3-0.7; the ball mill sets the ball mill speed to 50-800rpm; the operating time is 0.1 hour to 30 hours, and during the ball milling period, it is necessary to stop the machine from time to time to open the tank to release gas and lower the temperature.

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