Integrated treatment device and method for leachate from garbage transfer station

Abstract

The present invention discloses an integrated treatment device and method for leachate from a garbage transfer station. The treatment device includes an independently arranged treatment unit and a control unit. The treatment unit includes a regulating tank, a coagulation sedimentation tank, a flotation tank, an intermediate water tank, an anaerobic digestion tank, an anoxic tank, an aerobic tank, an MBR tank and a clear water tank which are separated and interconnected in sequence; the control area includes an equipment room and a control room. The present invention adopts a treatment process of coagulation-flotation-anaerobic digestion-anoxic-aerobic-MBR in combination with the water quality characteristics of the leachate from the garbage transfer station; and adopts an integrated treatment mode in combination with the water volume characteristics of the garbage leachate and the actual situation of the garbage transfer station, so as to finally realize the convenient, efficient and high-quality treatment of the leachate from the garbage transfer station.

Description

Technical Field

[0001] The invention relates to the technical field of garbage leachate treatment, and in particular to an integrated treatment device and method for leachate from a garbage transfer station. Background Art

[0002] During the operation of the garbage transfer station, leachate will be generated. This leachate has the characteristics of high organic matter concentration, high ammonia nitrogen content, and high heavy metal ion content. It also contains a large amount of suspended solids and grease. The water quality is complex and harmful. The amount of leachate from the garbage transfer station changes with the seasons, and even stops flowing in winter. If the leachate from the garbage transfer station is discharged directly into the environment, it will pose a huge threat to humans and the environment, so it must be treated before being discharged.

[0003] There are two ways to treat leachate from garbage transfer stations: off-site treatment and on-site treatment. Off-site treatment means that the wastewater from the transfer station is transported to a nearby sewage treatment plant for treatment by a transport vehicle. Due to the high concentration of pollutants in the wastewater, it cannot be directly discharged into the sewer network. It can only be collected and stored in a tank or liquid storage tank, and then transported out by a fecal suction truck. This method will incur high transportation costs and increase the operating burden on the sewage treatment plant. The leachate contains a large amount of organic matter, and anaerobic digestion will occur during storage and transportation, producing flammable and toxic and harmful gases such as methane, which increases the risk of storage and transportation. In addition, there is also a risk of leakage during storage and transportation. On-site treatment means that wastewater treatment facilities are specially set up in the station, and after the treatment meets the standards, it can be discharged into the municipal pipe network. However, for some garbage transfer stations, the water volume is small and the time distribution is uneven. The construction of fixed treatment facilities will cause the equipment to shut down due to the interruption of raw water supply, which is not economical from the perspective of investment and treatment costs. In order to reduce costs, many garbage transfer stations currently use oil separators, multi-function pressure release devices and sedimentation tanks to perform simple pretreatment of leachate, which cannot effectively remove the main pollutants in the leachate, and the equipment cannot operate efficiently. Therefore, according to the characteristics and treatment status of leachate in garbage transfer stations, it is very necessary to develop treatment technologies and devices that are easy to move, have good treatment effects and are low in cost. Summary of the invention

[0004] The present invention aims to overcome the above-mentioned problems existing in the prior art of leachate treatment in garbage transfer stations, and provides an integrated treatment device and method for leachate from garbage transfer stations. In combination with the water quality characteristics of the leachate from garbage transfer stations, a treatment process of coagulation-flotation-anaerobic digestion-anoxic-aerobic-MBR is adopted; in combination with the water volume characteristics of the garbage leachate and the actual situation of the garbage transfer station, an integrated treatment mode is adopted, and finally convenient, efficient and high-quality treatment of the leachate from the garbage transfer station is achieved.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A garbage transfer station leachate integrated treatment device comprises an independently arranged treatment unit and a control unit, wherein the treatment unit comprises a regulating tank, a coagulation sedimentation tank, a flotation tank, an intermediate water tank, an anaerobic digestion tank, an anoxic tank, an aerobic tank, an MBR tank and a clear water tank which are separated in sequence and interconnected; and the control area comprises an equipment room and a control room.

[0007] The present invention adopts the treatment process of coagulation-flotation-anaerobic digestion-anoxic-aerobic-MBR in view of the water quality characteristics of the leachate from the garbage transfer station, and sets up a regulating tank, a coagulation sedimentation tank, an air flotation tank, an intermediate water tank, an anaerobic digestion tank, anoxic tank, aerobic tank, MBR tank and a clear water tank, and integrates them into an integrated device; at the same time, an equipment room and a control room are set up to place auxiliary equipment and automatic control equipment, etc., respectively, to assist in the reaction and control of the equipment. The integrated device in the present invention has a modular design, is easy to move, has a compact structure, can be placed on the ground or buried underground, occupies a small area, and can effectively reduce the cost of infrastructure investment.

[0008] Preferably, a basket grille is provided at the entrance of the regulating tank, which can intercept and remove larger suspended matter and floating matter in the leachate, which is beneficial to the subsequent treatment of the leachate.

[0009] Preferably, the coagulation sedimentation tank includes a reaction zone and a sedimentation zone connected to each other, the reaction zone is connected to the regulating tank, and the sedimentation zone is connected to the flotation tank. The reaction zone is used for adding coagulants and coagulant aids and other reagents for reaction, and the sedimentation zone is used for sedimentation and separation of flocs generated after the reaction.

[0010] Preferably, the flotation tank includes a flotation reaction zone and a flotation contact zone, the flotation reaction zone is connected to the coagulation sedimentation tank, and the flotation contact zone is connected to the intermediate water tank. The flotation reaction zone is used for adding coagulant aids for reaction, and the flotation contact zone is used for introducing high-pressure dissolved air water for flotation.

[0011] Preferably, the anaerobic digester is provided with a plurality of staggered baffles, one end of the baffle is connected to the side wall of the anaerobic digester, and the other end forms a water passage between the side wall of the opposite side of the anaerobic digester; and the anaerobic digester is provided with anaerobic sludge. The baffles are provided in the anaerobic digester to extend the flow path of the leachate in the anaerobic digester, and the anaerobic reaction time can be extended while reducing the area of ​​the anaerobic digester, thereby improving the treatment efficiency of the anaerobic digester.

[0012] As an effective method, the anoxic tank includes an anaerobic zone and an anoxic zone connected to each other, the anaerobic zone is connected to the anaerobic digestion tank, and the anoxic zone is connected to the aerobic tank; anaerobic sludge is provided in both the anaerobic zone and the anoxic zone. In the anaerobic zone, polyphosphate bacteria in the sludge release phosphorus and absorb low-level fatty acids, etc.; in the anoxic zone, denitrifying bacteria in the sludge convert nitrate into nitrogen.

[0013] Preferably, the aerobic pool is provided with an aeration device and aerobic sludge.

[0014] Preferably, a digestate reflux pump and a digestate reflux pipeline are provided in the aerobic pool, and the digestate reflux pipeline is connected to the anoxic pool. The digestate after aerobic treatment in the aerobic pool can be pumped into the anoxic pool by the digestate reflux pump to continue denitrification.

[0015] Preferably, an aeration device and an MBR membrane assembly are provided in the MBR pool.

[0016] The present invention also provides a method for treating leachate from a garbage transfer station using the above-mentioned integrated treatment device, comprising the following steps:

[0017] (1) The leachate enters the regulating tank for pH adjustment;

[0018] (2) The leachate after pH adjustment enters the coagulation sedimentation tank, and a compound coagulant and a coagulant aid are added for coagulation and sedimentation;

[0019] (3) The supernatant from the coagulation sedimentation tank enters the flotation tank, where it is flotated and the surface scum is removed, and the effluent enters the intermediate water tank;

[0020] (4) The effluent from the intermediate pool is sequentially treated by the anaerobic digestion tank, the anoxic tank, and the aerobic tank;

[0021] (5) The effluent from the aerobic pool enters the MBR pool, and after biological treatment and mud-water separation, the effluent finally enters the clean water pool.

[0022] In view of the water quality characteristics of the leachate from the garbage transfer station, the present invention adopts a treatment process of coagulation-flotation-anaerobic digestion-anoxic-aerobic-MBR. In the coagulation sedimentation tank, the suspended solids and oil in the leachate gradually form flocs under the action of the compound coagulant and the coagulant aid, accumulate into a thin mud layer, and slide down and discharge by its own gravity; the supernatant flows to the flotation tank, and under the action of flotation, the tiny suspended solids in the leachate can adhere to the surface of the bubbles and float up with the bubbles to be removed; after being homogenized in the intermediate water tank, the effluent enters the anaerobic digestion tank to perform biological anaerobic digestion reaction to remove organic matter; gas is generated during the anaerobic digestion process, which stirs the mud-water mixture to make the sludge suspended, thereby increasing the contact area between the mud and water. Improve pollutant removal rate; the effluent from anaerobic digestion enters the anoxic tank, where the polyphosphate bacteria in the sludge release phosphorus and absorb low-level fatty acids; in the anoxic zone, the denitrifying bacteria in the sludge convert nitrates into nitrogen; the effluent from the anaerobic digestion tank enters the aerobic tank, where the nitrifying bacteria in the aerobic sludge convert ammonia into nitrates, heterotrophic microorganisms convert organic matter into water and carbon dioxide, and polyphosphate bacteria absorb phosphorus to achieve denitrification and dephosphorization of the leachate; the effluent from the aerobic tank enters the MBR tank, where the heterotrophic bacteria in the sludge convert the remaining organic matter into water and carbon dioxide, further removing the organic matter, and at the same time separating mud and water through the MBR membrane, and the treated water finally enters the clear water tank and can meet the discharge standards.

[0023] The present invention adopts a treatment process combining physicochemical treatment technology with biochemical treatment technology, avoiding the defects of a single process and being more economical and efficient while ensuring the quality of effluent. Compared with the existing biochemical + physicochemical combined treatment process of landfill leachate, the present invention sets physicochemical treatment before and after biochemical treatment. The physicochemical treatment before biochemical treatment removes suspended solids and emulsified oil and other substances in the leachate, reduces the pressure of biochemical treatment, avoids the blockage of biochemical reactor and the pollution of filler; the physicochemical treatment after biochemical treatment uses MBR membrane to separate mud and water, ensuring that the effluent quality meets the standard.

[0024] Preferably, the compound coagulant in step (2) includes PAC and fly ash-based coagulant; the addition amount of PAC is 15-30 mg / L, and the addition amount of fly ash-based coagulant is 5-15 mg / L; the coagulant aid is PAM, and the addition amount of PAM is 35-65 mg / L.

[0025] The present invention adds PAC and fly ash-based coagulant as a composite coagulant in a coagulation and precipitation unit, and adds an organic polymer coagulant PAM for coagulation aid. PAC (polyaluminium chloride) is an inorganic polymer coagulant, which forms multi-nuclear complex ions through hydroxyl bridging, can instantly neutralize the negative charge of colloid particles in water, make the colloid particles unstable, rapidly coagulate, further bridge to form flocs, and rapidly precipitate; it has a high degree of electrical neutralization and bridging effect on colloids and particles in water, can strongly remove trace poisons and heavy metal ions, and has stable performance. Fly ash is a waste discharged from coal-fired boilers such as thermal power plants, has the characteristics of small particles, multiple pores, and large specific surface area, and has a large number of active sites such as Al and Si, which can be physically and chemically adsorbed with pollutants. The present invention adds fly ash-based coagulant and PAC as a composite coagulant, which can integrate physical adsorption and chemical coagulation, and better remove impurities such as colloidal particles, tiny suspended matter and metal ions in leachate. The organic polymer coagulant added in the present invention has a huge linear molecule, and the chain links on the molecule have a strong adsorption effect on the colloidal particles in the leachate, forming a "colloid-polymer-colloid" flocculent body, which settles, and the colloid particles are adsorbed and bridged on the polymer chain links. The precipitate finally formed can collect and capture the colloid and other particles in the leachate during its own sedimentation process, so that the colloid particles are bonded, the adsorption force and aggregation ability between the suspended particles are increased, and the coagulation and precipitation are promoted. Aiming at the complex pollutant characteristics of the leachate of the garbage transfer station, the present invention adopts the combined action of the compound coagulant and the coagulant. Compared with the addition of a single type of coagulant and coagulant, the alum flocs formed by the combined action of the compound coagulant and the coagulant are larger and denser, the floc sedimentation speed is fast, the leachate after treatment is obviously stratified, the water quality is clear, and the coagulation and precipitation effect is better.

[0026] Preferably, the preparation method of the fly ash-based coagulant is:

[0027] A) adding fly ash into a mixed solution of hydrochloric acid and sulfuric acid to soak and wash to obtain pickled fly ash;

[0028] B) reacting the fly ash after pickling with an epoxy silane coupling agent to obtain epoxy-modified fly ash;

[0029] C) reacting epoxy-modified fly ash with sodium allyloxyhydroxypropyl sulfonate to obtain allyl-modified fly ash;

[0030] D) subjecting the allyl-modified fly ash and heptamethyltrisiloxane to a hydrosilylation reaction to obtain the fly ash-based coagulant.

[0031] In view of the fact that the emulsified oil contained in the leachate of the garbage transfer station is difficult to separate and remove from water, the present invention performs surface modification on fly ash to prepare a fly ash-based coagulant with good demulsification effect. First, the present invention performs acid washing on the fly ash to increase its specific surface area and surface adsorption sites; then the fly ash surface is modified with an epoxy silane coupling agent to introduce epoxy groups on its surface; then, through the ring-opening reaction between the epoxy groups on the fly ash surface and the hydroxyl groups in sodium allyloxyhydroxypropyl sulfonate, sodium allyloxyhydroxypropyl sulfonate is connected to the fly ash surface, and unsaturated double bonds and sulfonate ions are introduced on the fly ash surface; finally, through the silylation reaction of the unsaturated double bonds and the silicon-hydrogen bonds in heptamethyltrisiloxane, the organosilicon compound is connected to the fly ash surface. The surface of the fly ash-based coagulant finally obtained is modified with sulfonate ions and organosilicon compounds at the same time. Through the electrical neutralization effect of sulfonate ions and the reduction of oil-water interfacial tension by organosilicon compounds, it can play a good demulsification effect and promote oil-water separation. Combined with the adsorption properties of fly ash, it can effectively remove the emulsified oil in the leachate, achieving a better pretreatment effect.

[0032] Preferably, in step A), the concentration of hydrochloric acid is 5-10 mol / L, the concentration of sulfuric acid is 20-30%, the volume ratio of hydrochloric acid to sulfuric acid in the mixed solution is 1:2-3; the mass ratio of fly ash to the mixed solution is 1:4-6, and the soaking time is 4-6 hours;

[0033] The reaction conditions of step B) are as follows: adding an epoxy silane coupling agent to xylene to prepare a silane coupling agent solution with a mass fraction of 3 to 5%, adding the fly ash obtained after acid washing to the silane coupling agent solution at a mass volume ratio of 1 g:30 to 50 mL, stirring and reacting at 60 to 80° C. for 4 to 6 hours to obtain epoxy-modified fly ash;

[0034] The reaction conditions of step C) are as follows: sodium allyloxyhydroxypropyl sulfonate and epoxy-modified fly ash in a mass ratio of 1:2-3 are added to a mixed solvent of water and ethanol in a volume ratio of 1:9-3:7, the mass ratio of epoxy-modified fly ash to the mixed solvent is 1:10-15, and then 3-5% of NaOH by mass of the mixed solvent is added, and after stirring evenly, nitrogen is introduced at 60-70° C. for reaction for 5-8 hours to obtain allyl-modified fly ash;

[0035] The reaction conditions of step D) are: dispersing the allyl-modified fly ash in DMF, adding chloroplatinic acid catalyst, and then adding heptamethyltrisiloxane, stirring and reacting at 50-60° C. for 1-2 hours to obtain the fly ash-based coagulant; the mass ratio of the added allyl-modified fly ash to heptamethyltrisiloxane is 3-4:1.

[0036] Preferably, in step (3), a coagulant is added to the flotation reaction zone in the flotation tank for reaction, and high-pressure dissolved air water is introduced into the flotation contact zone for flotation; the coagulant is PAM, and the amount of PAM added is 10 to 40 mg / L; the high-pressure dissolved air water introduced is 5 to 15% of the mass of the water to be treated, and the pressure when preparing the high-pressure dissolved air water is 0.2 to 0.6 MPa.

[0037] Preferably, in step (4), the dissolved oxygen content of the wastewater in the anaerobic digester is not higher than 0.2 mg / L, and the hydraulic retention time in the anaerobic digester is 2 to 4 hours; the dissolved oxygen content in the anoxic tank is 0.3 to 0.6 mg / L; the hydraulic retention time in the anoxic tank is 5 to 7 hours; the dissolved oxygen content in the aerobic tank is 0.5 to 2.0 mg / L, and the hydraulic retention time in the aerobic tank is 8 to 14 hours.

[0038] Preferably, the reflux ratio of the digestate in the aerobic tank is 100-500%.

[0039] Preferably, the dissolved oxygen in the MBR tank in step (5) is 1 to 3 mg / L.

[0040] Therefore, the present invention has the following beneficial effects:

[0041] (1) The physicochemical and biochemical processes are combined and applied to the treatment of leachate from the garbage transfer station. In view of the water quality characteristics of the leachate from the garbage transfer station, the present invention adopts a sewage treatment process combining physicochemical treatment technology with biochemical treatment technology, thereby avoiding the defects of a single process and being more economical and efficient while ensuring the quality of the effluent. Compared with the general biochemical + physicochemical combined treatment process for leachate from garbage, the present invention provides physicochemical treatment before and after the biochemical treatment. The physicochemical treatment before the biochemical treatment removes suspended solids and emulsified oil and other substances in the leachate, thereby reducing the pressure of the biochemical treatment and avoiding the problems of blockage of the biochemical reactor and contamination of the filler. The physicochemical treatment after the biochemical treatment uses the MBR membrane to separate mud and water, thereby ensuring that the effluent quality meets the standard.

[0042] (2) The treatment of leachate from garbage transfer stations is optimized and integrated into an integrated device. In view of the small and fluctuating water volume of leachate from garbage transfer stations and the scattered characteristics of garbage transfer stations, the present invention optimizes the combination of treatment reactors for leachate from garbage transfer stations and integrates them into an integrated device. The integrated device has a modular design, is easy to move, has a compact structure, can be placed on the ground or buried underground, occupies a small area, and can effectively reduce infrastructure investment costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a structural schematic diagram of the integrated processing device in the present invention.

[0044] In the figure: 1 regulating tank, 2 coagulation sedimentation tank, 2.1 reaction zone, 2.2 sedimentation zone, 3 flotation tank, 3.1 flotation reaction zone, 3.2 flotation contact zone, 4 intermediate water tank, 5 anaerobic digester, 5.1 baffle, 6 anoxic tank, 6.1 anaerobic zone, 6.2 anoxic zone, 7 aerobic tank, 8 MBR tank, 9 clear water tank, 10 equipment room, 11 control room, 12 basket grille, 13 aeration device, 14 digestate return pump. DETAILED DESCRIPTION

[0045] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0046] In the present invention, unless otherwise specified, all equipment and raw materials can be purchased from the market or are commonly used in the industry. The methods in the following embodiments, unless otherwise specified, are conventional methods in the art.

[0047] The experimental water in the embodiment of the present invention was taken from the leachate produced by a garbage transfer station in Zhejiang Province. The water quality is as follows: CODcr is 30-35 mg·mL -1 , BOD5 is 8~10mg·mL -1 SS: 8-10 mg mL -1 , NH4 + -N is 0.6~0.7mg·mL -1 , pH is 5.5-7.0; conventional water quality indicators are determined using national standard methods.

[0048] Overall embodiment:

[0049] An integrated treatment device for leachate from a garbage transfer station, such as Figure 1 As shown, it includes independently arranged processing units and control units, the processing unit includes a regulating tank 1, a coagulation sedimentation tank 2, a flotation tank 3, an intermediate water tank 4, an anaerobic digestion tank 5, an anoxic tank 6, an aerobic tank 7, an MBR tank 8 and a clear water tank 9 which are separated in sequence and interconnected; the control area includes an equipment room 10 and a control room 11;

[0050] A basket grille 12 is provided at the entrance of the regulating tank;

[0051] The coagulation sedimentation tank includes a reaction zone 2.1 and a sedimentation zone 2.2 which are connected to each other. The reaction zone is connected to the regulating tank, and the sedimentation zone is connected to the flotation tank.

[0052] The flotation tank includes a flotation reaction zone 3.1 and a flotation contact zone 3.2 which are connected to each other. The flotation reaction zone is connected to the sedimentation zone in the coagulation sedimentation tank, and the flotation contact zone is connected to the intermediate water tank.

[0053] The anaerobic digester is provided with a plurality of staggered baffles 5.1, one end of the baffle is connected to the side wall of the anaerobic digester, and the other end forms a water passage between the side wall of the opposite side of the anaerobic digester; the anaerobic digester is provided with anaerobic sludge;

[0054] The anoxic tank includes an anaerobic zone 6.1 and an anoxic zone 6.2 which are connected to each other. The anaerobic zone is connected to the anaerobic digestion tank, and the anoxic zone is connected to the aerobic tank. Anaerobic sludge is provided in both the anaerobic zone and the anoxic zone.

[0055] The aerobic tank is provided with an aeration device 13 and aerobic sludge; the aerobic tank is provided with a digestion liquid return pump 14 and a digestion liquid return pipeline, and the digestion liquid return pipeline is connected to the anaerobic zone in the anoxic tank;

[0056] The MBR pool is equipped with an aeration device and an MBR membrane assembly.

[0057] The above-mentioned integrated treatment device is used to treat the leachate from the garbage transfer station, and the method includes the following steps:

[0058] (1) The leachate enters the regulating tank for pH adjustment, and the pH of the leachate is adjusted to 7.5-8.5;

[0059] (2) the leachate after pH adjustment enters the coagulation sedimentation tank, a compound coagulant and a coagulant aid are added in the reaction zone to react, and precipitation is carried out in the sedimentation zone; the compound coagulant includes PAC and a fly ash-based coagulant; the addition amount of PAC is 15 to 30 mg / L, the addition amount of the fly ash-based coagulant is 5 to 15 mg / L; the coagulant aid is PAM, and the addition amount of PAM is 35 to 65 mg / L;

[0060] (3) The supernatant of the coagulation sedimentation tank enters the flotation tank, a coagulant is added to the flotation reaction zone to react, and then high-pressure dissolved air water is introduced into the flotation contact zone to perform flotation and remove surface scum, and the effluent enters the intermediate water tank; the coagulant is PAM, the amount of PAM added is 10-40 mg / L, the pressure when preparing the high-pressure dissolved air water is controlled at 0.2-0.6 MPa, and the high-pressure dissolved air water introduced is 5-15% of the mass of the water to be treated;

[0061] (4) The effluent from the intermediate water tank is biologically treated in the anaerobic digestion tank, the anoxic tank and the aerobic tank in sequence; the dissolved oxygen content of the wastewater in the anaerobic digestion tank is not higher than 0.2 mg / L, and the hydraulic retention time in the anaerobic digestion tank is 2 to 4 hours; the dissolved oxygen content in the anoxic tank is 0.3 to 0.6 mg / L; the hydraulic retention time in the anoxic tank is 5 to 7 hours; the dissolved oxygen content in the aerobic tank is 0.5 to 2.0 mg / L, and the hydraulic retention time in the aerobic tank is 8 to 14 hours; the digestate in the aerobic tank is returned to the anaerobic zone in the anoxic tank, and the return ratio is 100 to 500%;

[0062] (5) The effluent from the aerobic pool enters the MBR pool. After biological treatment and mud-water separation, the effluent finally enters the clean water pool. The dissolved oxygen in the MBR pool is 1-3 mg / L.

[0063] Wherein, the preparation method of fly ash-based coagulant is:

[0064] A) adding fly ash into a mixed solution of hydrochloric acid and sulfuric acid, soaking and washing to obtain acid-washed fly ash; the concentration of hydrochloric acid is 5-10 mol / L, the concentration of sulfuric acid is 20-30%, the volume ratio of hydrochloric acid to sulfuric acid in the mixed solution is 1:2-3; the mass ratio of fly ash to the mixed solution is 1:4-6, and the soaking time is 4-6 hours;

[0065] B) adding an epoxy silane coupling agent to xylene to prepare a silane coupling agent solution with a mass fraction of 3-5%, adding the fly ash obtained after acid washing to the silane coupling agent solution at a mass volume ratio of 1g:30-50mL, stirring and reacting at 60-80°C for 4-6h to obtain epoxy-modified fly ash;

[0066] C) adding sodium allyloxyhydroxypropyl sulfonate and epoxy-modified fly ash in a mass ratio of 1:2-3 to a mixed solvent of water and ethanol in a volume ratio of 1:9-3:7, the mass ratio of epoxy-modified fly ash to the mixed solvent is 1:10-15, and then adding 3-5% NaOH by mass of the mixed solvent, stirring evenly, passing nitrogen at 60-70° C. for reaction for 5-8 hours to obtain allyl-modified fly ash; D) dispersing allyl-modified fly ash in DMF, adding chloroplatinic acid catalyst, and then adding heptamethyltrisiloxane, stirring and reacting at 50-60° C. for 1-2 hours to obtain the fly ash-based coagulant; the mass ratio of the added allyl-modified fly ash to heptamethyltrisiloxane is 3-4:1.

[0067] Embodiment 1:

[0068] The above-mentioned integrated treatment device is used to treat the leachate from the garbage transfer station, and the method includes the following steps:

[0069] (1) The leachate enters the regulating tank for pH adjustment, and the pH of the leachate is adjusted to 7.5-8.5;

[0070] (2) The leachate after pH adjustment enters the coagulation sedimentation tank, and a compound coagulant and a coagulant aid are added in the reaction zone to react, and precipitation is carried out in the sedimentation zone; the compound coagulant includes PAC and a fly ash-based coagulant; the addition amount of PAC is 20 mg / L, and the addition amount of the fly ash-based coagulant is 10 mg / L; the coagulant aid is PAM, and the addition amount of PAM is 50 mg / L;

[0071] (3) The supernatant of the coagulation sedimentation tank enters the flotation tank, a coagulant is added to the flotation reaction zone for reaction, and then high-pressure dissolved air water is introduced into the flotation contact zone for flotation and removal of surface scum, and the effluent enters the intermediate water tank; the coagulant is PAM, the amount of PAM added is 30 mg / L, the pressure during the preparation of high-pressure dissolved air water is controlled at 0.5 MPa, and the high-pressure dissolved air water introduced is 10% of the mass of the water to be treated;

[0072] (4) The effluent from the intermediate water tank is biologically treated in the anaerobic digester, anoxic tank and aerobic tank in sequence; the sludge concentration in the anaerobic digester, anoxic tank and aerobic tank is 4000 mg / L, the dissolved oxygen content of the wastewater in the anaerobic digester is maintained at a level not higher than 0.2 mg / L, and the hydraulic retention time in the anaerobic digester is 3 hours; the dissolved oxygen content in the anoxic tank is maintained at 0.45±0.15 mg / L; the hydraulic retention time in the anoxic tank is 6 hours; the dissolved oxygen content in the aerobic tank is controlled to 1.25±0.75 mg / L through aeration, and the hydraulic retention time in the aerobic tank is 11 hours; the digestate in the aerobic tank is returned to the anaerobic zone in the anoxic tank, and the return ratio is 250%;

[0073] (5) The effluent from the aerobic pool enters the MBR pool, and after biological treatment and mud-water separation, the effluent finally enters the clean water pool; the sludge concentration in the MBR pool is 4000 mg / L, and the dissolved oxygen content of the wastewater in the MBR pool is controlled to 2±1 mg / L through aeration;

[0074] Wherein, the preparation method of fly ash-based coagulant is:

[0075] A) adding fly ash into a mixed solution of hydrochloric acid and sulfuric acid, soaking and washing to obtain acid-washed fly ash; the concentration of hydrochloric acid is 8 mol / L, the concentration of sulfuric acid is 25%, the volume ratio of hydrochloric acid to sulfuric acid in the mixed solution is 1:2.5; the mass ratio of fly ash to the mixed solution is 1:5, and the soaking time is 5 hours;

[0076] B) adding silane coupling agent KH560 to xylene to prepare a silane coupling agent solution with a mass fraction of 4%, adding the fly ash obtained after acid washing to the silane coupling agent solution at a mass volume ratio of 1g:40mL, stirring and reacting at 70°C for 5h to obtain epoxy-modified fly ash;

[0077] C) adding sodium allyloxyhydroxypropyl sulfonate and epoxy-modified fly ash in a mass ratio of 1:2.5 to a mixed solvent of water and ethanol in a volume ratio of 2:8, wherein the mass ratio of epoxy-modified fly ash to the mixed solvent is 1:12, and then adding 4% NaOH by mass of the mixed solvent, stirring evenly, passing nitrogen gas at 65° C. for reaction for 6 hours to obtain allyl-modified fly ash;

[0078] D) dispersing the allyl-modified fly ash in DMF, adding 25 ppm of chloroplatinic acid catalyst, and then adding heptamethyltrisiloxane, stirring and reacting at 55° C. for 1.5 hours to obtain the fly ash-based coagulant; the mass ratio of the added allyl-modified fly ash to the heptamethyltrisiloxane is 3.5:1.

[0079] Embodiment 2:

[0080] The above-mentioned integrated treatment device is used to treat the leachate from the garbage transfer station, and the method includes the following steps:

[0081] (1) The leachate enters the regulating tank for pH adjustment, and the pH of the leachate is adjusted to 7.5-8.5;

[0082] (2) The leachate after pH adjustment enters the coagulation sedimentation tank, and a compound coagulant and a coagulant aid are added in the reaction zone to react, and precipitation is carried out in the sedimentation zone; the compound coagulant includes PAC and a fly ash-based coagulant; the addition amount of PAC is 15 mg / L, and the addition amount of the fly ash-based coagulant is 15 mg / L; the coagulant aid is PAM, and the addition amount of PAM is 65 mg / L;

[0083] (3) The supernatant of the coagulation sedimentation tank enters the flotation tank, a coagulant is added to the flotation reaction zone for reaction, and then high-pressure dissolved air water is introduced into the flotation contact zone for flotation and removal of surface scum, and the effluent enters the intermediate water tank; the coagulant is PAM, the amount of PAM added is 10 mg / L, the pressure during the preparation of high-pressure dissolved air water is controlled at 0.6 MPa, and the high-pressure dissolved air water introduced is 5% of the mass of the water to be treated;

[0084] (4) The effluent from the intermediate water tank is biologically treated in the anaerobic digester, anoxic tank and aerobic tank in sequence; the sludge concentration in the anaerobic digester, anoxic tank and aerobic tank is 4000 mg / L, the dissolved oxygen content of the wastewater in the anaerobic digester is maintained at a level not higher than 0.2 mg / L, and the hydraulic retention time in the anaerobic digester is 3 hours; the dissolved oxygen content in the anoxic tank is maintained at 0.45±0.15 mg / L; the hydraulic retention time in the anoxic tank is 6 hours; the dissolved oxygen content in the aerobic tank is controlled to 1.25±0.75 mg / L through aeration, and the hydraulic retention time in the aerobic tank is 11 hours; the digestate in the aerobic tank is returned to the anaerobic zone in the anoxic tank, and the return ratio is 250%;

[0085] (5) The effluent from the aerobic pool enters the MBR pool, and after biological treatment and mud-water separation, the effluent finally enters the clean water pool; the sludge concentration in the MBR pool is 4000 mg / L, and the dissolved oxygen content of the wastewater in the MBR pool is controlled to 2±1 mg / L through aeration;

[0086] Wherein, the preparation method of fly ash-based coagulant is:

[0087] A) adding fly ash into a mixed solution of hydrochloric acid and sulfuric acid, soaking and washing to obtain acid-washed fly ash; the concentration of hydrochloric acid is 5 mol / L, the concentration of sulfuric acid is 30%, the volume ratio of hydrochloric acid to sulfuric acid in the mixed solution is 1:2; the mass ratio of fly ash to the mixed solution is 1:4, and the soaking time is 6 hours;

[0088] B) adding silane coupling agent KH560 to xylene to prepare a silane coupling agent solution with a mass fraction of 3%, adding the fly ash obtained after acid washing to the silane coupling agent solution at a mass volume ratio of 1g:50mL, stirring and reacting at 60°C for 6h to obtain epoxy-modified fly ash;

[0089] C) adding sodium allyloxyhydroxypropyl sulfonate and epoxy-modified fly ash in a mass ratio of 1:2 to a mixed solvent of water and ethanol in a volume ratio of 3:7, wherein the mass ratio of epoxy-modified fly ash to the mixed solvent is 1:10, and then adding 3% NaOH by mass of the mixed solvent, stirring evenly, and reacting at 60° C. for 8 hours under nitrogen to obtain allyl-modified fly ash;

[0090] D) dispersing the allyl-modified fly ash in DMF, adding 25 ppm of chloroplatinic acid catalyst, and then adding heptamethyltrisiloxane, stirring and reacting at 50° C. for 2 hours to obtain the fly ash-based coagulant; the mass ratio of the added allyl-modified fly ash to the heptamethyltrisiloxane is 3:1.

[0091] Embodiment 3:

[0092] The above-mentioned integrated treatment device is used to treat the leachate from the garbage transfer station, and the method includes the following steps:

[0093] (1) The leachate enters the regulating tank for pH adjustment, and the pH of the leachate is adjusted to 8.5;

[0094] (2) The leachate after pH adjustment enters the coagulation sedimentation tank, and a compound coagulant and a coagulant aid are added in the reaction zone to react, and precipitation is carried out in the sedimentation zone; the compound coagulant includes PAC and a fly ash-based coagulant; the addition amount of PAC is 30 mg / L, and the addition amount of the fly ash-based coagulant is 5 mg / L; the coagulant aid is PAM, and the addition amount of PAM is 35 mg / L;

[0095] (3) The supernatant of the coagulation sedimentation tank enters the flotation tank, a coagulant is added to the flotation reaction zone for reaction, and then high-pressure dissolved air water is introduced into the flotation contact zone for flotation and removal of surface scum, and the effluent enters the intermediate water tank; the coagulant is PAM, the amount of PAM added is 30 mg / L, the pressure during the preparation of high-pressure dissolved air water is controlled at 0.2 MPa, and the high-pressure dissolved air water introduced is 15% of the mass of the water to be treated;

[0096] (4) The effluent from the intermediate water tank is biologically treated in the anaerobic digester, anoxic tank and aerobic tank in sequence; the sludge concentration in the anaerobic digester, anoxic tank and aerobic tank is 4000 mg / L, the dissolved oxygen content of the wastewater in the anaerobic digester is maintained at a level not higher than 0.2 mg / L, and the hydraulic retention time in the anaerobic digester is 3 hours; the dissolved oxygen content in the anoxic tank is maintained at 0.45±0.15 mg / L; the hydraulic retention time in the anoxic tank is 6 hours; the dissolved oxygen content in the aerobic tank is controlled to 1.25±0.75 mg / L through aeration, and the hydraulic retention time in the aerobic tank is 11 hours; the digestate in the aerobic tank is returned to the anaerobic zone in the anoxic tank, and the return ratio is 250%;

[0097] (5) The effluent from the aerobic pool enters the MBR pool, and after biological treatment and mud-water separation, the effluent finally enters the clean water pool; the sludge concentration in the MBR pool is 4000 mg / L, and the dissolved oxygen content of the wastewater in the MBR pool is controlled to 2±1 mg / L through aeration;

[0098] Wherein, the preparation method of fly ash-based coagulant is:

[0099] A) adding fly ash into a mixed solution of hydrochloric acid and sulfuric acid, soaking and washing to obtain acid-washed fly ash; the concentration of hydrochloric acid is 10 mol / L, the concentration of sulfuric acid is 20%, the volume ratio of hydrochloric acid to sulfuric acid in the mixed solution is 1:3; the mass ratio of fly ash to the mixed solution is 1:6, and the soaking time is 4 hours;

[0100] B) adding silane coupling agent KH560 to xylene to prepare a silane coupling agent solution with a mass fraction of 5%, adding the fly ash obtained after acid washing to the silane coupling agent solution at a mass volume ratio of 1g:30mL, stirring and reacting at 80°C for 4h to obtain epoxy-modified fly ash;

[0101] C) adding sodium allyloxyhydroxypropyl sulfonate and epoxy-modified fly ash in a mass ratio of 1:3 to a mixed solvent of water and ethanol in a volume ratio of 1:9, the mass ratio of epoxy-modified fly ash to the mixed solvent is 1:15, and then adding 5% NaOH by mass of the mixed solvent, stirring evenly, and reacting at 70° C. for 5 hours with nitrogen to obtain allyl-modified fly ash;

[0102] D) dispersing the allyl-modified fly ash in DMF, adding 25 ppm of chloroplatinic acid catalyst, and then adding heptamethyltrisiloxane, stirring and reacting at 60° C. for 1 hour to obtain the fly ash-based coagulant; the mass ratio of the added allyl-modified fly ash to the heptamethyltrisiloxane is 4:1.

[0103] Comparative Example 1:

[0104] The difference between Comparative Example 1 and Example 1 is that only 30 mg / L of PAC is added in step (2), and no fly ash-based coagulant is added, and the rest is the same as in Example 1.

[0105] Comparative Example 2:

[0106] The difference between Comparative Example 2 and Example 1 is that only 30 mg / L of fly ash-based coagulant is added in step (2), and no PAC is added. The rest is the same as in Example 1.

[0107] Comparative Example 3:

[0108] The difference between Comparative Example 3 and Example 1 is that the preparation method of the fly ash-based coagulant is: fly ash is added to a mixed solution of hydrochloric acid and sulfuric acid, soaked and washed to obtain the fly ash-based coagulant; the concentration of hydrochloric acid is 5 mol / L, the concentration of sulfuric acid is 30%, and the volume ratio of hydrochloric acid to sulfuric acid in the mixed solution is 1:2; the mass ratio of fly ash to the mixed solution is 1:4, and the soaking time is 6 hours; the rest is the same as in Example 1.

[0109] Comparative Example 4:

[0110] The difference between Comparative Example 4 and Example 1 is that the preparation method of the fly ash-based coagulant is:

[0111] A) adding fly ash into a mixed solution of hydrochloric acid and sulfuric acid, soaking and washing to obtain acid-washed fly ash; the concentration of hydrochloric acid is 8 mol / L, the concentration of sulfuric acid is 25%, the volume ratio of hydrochloric acid to sulfuric acid in the mixed solution is 1:2.5; the mass ratio of fly ash to the mixed solution is 1:5, and the soaking time is 5 hours;

[0112] B) adding silane coupling agent KH560 to xylene to prepare a silane coupling agent solution with a mass fraction of 4%, adding the fly ash obtained after acid washing to the silane coupling agent solution at a mass volume ratio of 1g:40mL, stirring and reacting at 70°C for 5h to obtain epoxy-modified fly ash;

[0113] C) adding sodium allyloxyhydroxypropyl sulfonate and epoxy-modified fly ash in a mass ratio of 1:2.5 to a mixed solvent of water and ethanol in a volume ratio of 2:8, wherein the mass ratio of epoxy-modified fly ash to the mixed solvent is 1:12, and then adding 4% NaOH by mass of the mixed solvent, stirring evenly, passing nitrogen gas at 65° C. for reaction for 6 hours to obtain a fly ash-based coagulant;

[0114] The rest are the same as in Example 1.

[0115] Comparative Example 5:

[0116] A method for pretreating leachate from a garbage transfer station comprises the following steps:

[0117] (1) Add alkali to adjust the pH of the leachate to 7.5-8.5;

[0118] (2) adding a composite coagulant to the leachate obtained after adjusting the pH to carry out a coagulation reaction, wherein the composite coagulant includes PAC, a fly ash-based coagulant, sodium allyloxyhydroxypropyl sulfonate and heptamethyl trisiloxane; the addition amount of PAC is 20 mg / L, the addition amount of the fly ash-based coagulant is 10 mg / L, the addition amount of sodium allyloxyhydroxypropyl sulfonate is 4 mg / L; and the addition amount of heptamethyl trisiloxane is 1 mg / L;

[0119] (3) adding an organic polymer coagulant PAM to the leachate after the coagulation reaction to react and precipitate, and discharging the precipitated sludge; the amount of PAM added is 50 mg / L;

[0120] (4) adding an organic polymer coagulant aid PAM to the supernatant after precipitation again for reaction, the amount of PAM added is 30 mg / L, and then passing high-pressure dissolved air water and flotation, the pressure during the preparation of high-pressure dissolved air water is controlled at 0.5 MPa, the amount of high-pressure dissolved air water passed is 10% of the mass of the water to be treated, and the surface scum is removed to obtain the pre-treated leachate;

[0121] Among them, the preparation method of fly ash-based coagulant is: add fly ash into a mixed solution of hydrochloric acid and sulfuric acid, soak and wash to obtain the fly ash-based coagulant; the concentration of hydrochloric acid is 8 mol / L, the concentration of sulfuric acid is 25%, the volume ratio of hydrochloric acid and sulfuric acid in the mixed solution is 1:2.5; the mass ratio of fly ash to the mixed solution is 1:5, and the soaking time is 5 hours.

[0122] During the 30 days of stable operation, the water quality in the clear water tank in the above embodiments and comparative examples was continuously monitored, and the results are shown in Table 1.

[0123] Table 1: Results of water quality testing in the clean water pool.

[0124]

[0125] As can be seen from Table 1, the final effluent CODcr can reach 500 mg·L by using the method of the present invention in Examples 1 to 3. -1 Below, BOD5 is 100 mg·L -1 Below, SS is 20mg·L -1 Below, NH4 + -N is 40mg·L -1 Below, removal rates of 95%, 99% and 94% of organic matter, suspended solids and ammonia nitrogen were achieved, i.e. flexible, economical and efficient leachate treatment of garbage transfer stations was achieved.

[0126] In Comparative Example 1, only PAC was added as a coagulant, and in Comparative Example 2, only fly ash-based coagulant was added. The coagulation effect was significantly reduced compared with the composite coagulant, resulting in a decrease in the pretreatment effect, affecting the subsequent biological treatment, and causing the various indicators of the effluent to be significantly reduced compared with Example 1, indicating that the composite coagulant in the present invention also effectively improves the pretreatment effect. In Comparative Example 3, the sulfonic acid group and the organosilicon group were not modified on the surface of the fly ash; in Comparative Example 4, only the sulfonic acid group was modified on the surface of the fly ash, and the organosilicon group was not modified, and its demulsification performance was reduced, resulting in a decrease in the pretreatment effect, so that the various indicators of the effluent were reduced compared with Example 1; in Comparative Example 5, the sulfonate and the organosilicon compound were directly blended with the fly ash without connecting them to the surface of the fly ash, and the treatment effect in the embodiment could not be achieved either. This may be because when the sulfonic acid group and the organosilicon group were modified on the surface of the fly ash, their demulsification effect could cooperate with the adsorption effect of the fly ash, which was more conducive to oil-water separation.

Claims

1. A method for treating leachate from a garbage transfer station, characterized in that: The steps include: Step 1: The leachate enters the regulating tank for pH adjustment; Step 2: The leachate after pH adjustment enters a coagulation sedimentation tank, and a compound coagulant and a coagulant aid are added for coagulation and sedimentation; the compound coagulant includes PAC and a fly ash-based coagulant; Step 3: The supernatant of the coagulation sedimentation tank enters the flotation tank, where it is flotated and the surface scum is removed, and the effluent enters the intermediate water tank; Step 4: The effluent from the intermediate pool is sequentially treated by the anaerobic digestion tank, the anoxic tank and the aerobic tank; Step 5: The effluent from the aerobic pool enters the MBR pool, and after biological treatment and mud-water separation, the effluent finally enters the clean water pool; The preparation method of the fly ash-based coagulant is: A) adding fly ash into a mixed solution of hydrochloric acid and sulfuric acid to soak and wash to obtain acid-washed fly ash; B) reacting the acid-washed fly ash with an epoxy silane coupling agent to obtain epoxy-modified fly ash; C) reacting the epoxy-modified fly ash with sodium allyloxyhydroxypropyl sulfonate to obtain allyl-modified fly ash; D) subjecting allyl-modified fly ash and heptamethyltrisiloxane to a hydrosilylation reaction to obtain the fly ash-based coagulant.

2. The method for treating leachate from a garbage transfer station according to claim 1, wherein: The process is realized by an integrated treatment device for a garbage transfer station, the integrated treatment device for a garbage transfer station comprising an independently arranged treatment unit and a control unit, the treatment unit comprising a regulating tank (1), a coagulation sedimentation tank (2), an air flotation tank (3), an intermediate water tank (4), an anaerobic digestion tank (5), an anoxic tank (6), an aerobic tank (7), an MBR tank (8) and a clear water tank (9) which are separated in sequence and interconnected; the control unit comprises an equipment room (10) and a control room (11).

3. The method for treating leachate from a garbage transfer station according to claim 2, wherein: A basket grille (12) is provided at the entrance of the regulating tank.

4. The method for treating leachate from a garbage transfer station according to claim 2, wherein: The coagulation sedimentation tank comprises a reaction zone (2.1) and a sedimentation zone (2.2) which are connected to each other. The reaction zone is connected to the regulating tank, and the sedimentation zone is connected to the flotation tank.

5. The method for treating leachate from a garbage transfer station according to claim 2 or 4, characterized in that: The flotation tank comprises a flotation reaction zone (3.1) and a flotation contact zone (3.2) which are connected to each other. The flotation reaction zone is connected to the coagulation sedimentation tank, and the flotation contact zone is connected to the intermediate water tank.

6. The method for treating leachate from a garbage transfer station according to claim 2, characterized in that: The anaerobic digester is provided with a plurality of staggered baffles (5.1), one end of the baffle is connected to the side wall of the anaerobic digester, and the other end forms a water passage with the side wall on the opposite side of the anaerobic digester; and anaerobic sludge is provided in the anaerobic digester.

7. The method for treating leachate from a garbage transfer station according to claim 2, wherein: The anoxic tank comprises an anaerobic zone (6.1) and an anoxic zone (6.2) which are connected to each other. The anaerobic zone is connected to the anaerobic digestion tank, and the anoxic zone is connected to the aerobic tank. Anaerobic sludge is provided in both the anaerobic zone and the anoxic zone.

8. The method for treating leachate from a garbage transfer station according to claim 2, characterized in that: The aerobic pool is provided with an aeration device (13) and aerobic sludge.

9. The method for treating leachate from a garbage transfer station according to claim 2 or 8, characterized in that: A digestive liquid reflux pump (14) and a digestive liquid reflux pipeline are provided in the aerobic tank, and the digestive liquid reflux pipeline is connected to the anoxic tank.

10. The method for treating leachate from a garbage transfer station according to claim 2, characterized in that: The MBR pool is provided with an aeration device and an MBR membrane assembly.

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