Integrated treatment apparatus and method for leachate from garbage transfer station

Abstract

Disclosed is an integrated treatment apparatus and method for leachate from a garbage transfer station. The treatment apparatus comprises a treatment unit and a control unit which are independently arranged. The treatment unit comprises an adjustment tank, a coagulation sedimentation tank, an air flotation tank, a middle water tank, an anaerobic digestion tank, an anoxic tank, an aerobic tank, an MBR tank, and a clean water tank which are sequentially separated and in communication with each other. A control area comprises an equipment room and a control room. In view of the water quality characteristics of leachate from garbage transfer stations, the present invention uses a coagulation-air flotation-anaerobic digestion-anoxic-aerobic-MBR treatment process. In view of the characteristics of the amount of water in landfill leachate and the actual conditions of garbage transfer stations, an integrated treatment means is used, and finally, convenient, efficient, and high-quality treatment of leachate from garbage transfer stations is achieved.

Description

Integrated treatment device and method for leachate from a garbage transfer station Technical Field

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

[0002] During operation, waste transfer stations generate leachate, characterized by high concentrations of organic matter, ammonia nitrogen, and heavy metal ions. It also contains large amounts of suspended solids and oil, resulting in complex water quality and high hazards. The amount of leachate from waste transfer stations fluctuates with the seasons, and even dry-ups occur in winter. Directly discharging leachate into the environment poses a significant threat to both humans and the environment, so it must be treated before discharge.

[0003] There are two treatment options for leachate from waste transfer stations: off-site and on-site. Off-site treatment involves transporting wastewater from the transfer station to a nearby sewage treatment plant for treatment. Due to the high concentration of pollutants in the wastewater, it cannot be discharged directly into the sewer network. Instead, it is collected and stored in tanks or reservoirs before being transported away by suction trucks. This method incurs high transportation costs and places an increased operational burden on the sewage treatment plant. Leachate contains a large amount of organic matter, which undergoes anaerobic digestion during storage and transportation, producing flammable and toxic gases such as methane, increasing storage and transportation risks. Furthermore, there is the risk of leakage during storage and transportation. On-site treatment involves installing dedicated wastewater treatment facilities within the station. Once treated to meet standards, the wastewater can be discharged into the municipal pipeline network. However, for some waste transfer stations, water supply is limited and unevenly distributed over time. The construction of fixed treatment facilities can lead to equipment downtime due to raw water supply interruptions, making it uneconomical from a cost-effective perspective. To reduce costs, many waste transfer stations currently use simple leachate pretreatment systems such as oil-separating lifts, multi-function pressure relief devices, and sedimentation tanks. These systems fail to effectively remove key pollutants, and their operation is currently inefficient. Therefore, based on the characteristics and current treatment status of leachate from waste transfer stations, it is crucial to develop treatment technologies and devices that are easily transportable, effective, and low-cost.

[0004] Summary of the Invention

[0005] The present invention aims to overcome the above-mentioned problems existing in the prior art of leachate treatment at garbage transfer stations and provides an integrated leachate treatment device and method for garbage transfer stations. In combination with the water quality characteristics of the leachate at 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 leachate and the actual situation of the garbage transfer station, an integrated integrated treatment mode is adopted, ultimately achieving convenient, efficient and high-quality treatment of the leachate at the garbage transfer station.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A garbage transfer station leachate integrated 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 digester, 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.

[0008] This invention addresses the water quality characteristics of leachate from waste transfer stations and utilizes a coagulation-flotation-anaerobic digestion-anoxic-aerobic-MBR treatment process. This process integrates a regulating tank, a coagulation-sedimentation tank, a flotation tank, an intermediate water tank, an anaerobic digestion tank, anoxic tank, aerobic tank, MBR tank, and a clear water tank into an integrated system. Furthermore, an equipment room and a control room are provided to house auxiliary equipment and automated control devices, respectively, to assist in the reaction and control of the equipment. The modular design of this integrated system allows for easy mobility and a compact structure. It can be placed aboveground or underground, requiring minimal floor space and effectively reducing infrastructure investment costs.

[0009] Preferably, a basket screen is provided at the entrance of the regulating tank, which can intercept and remove large suspended solids and floating objects in the leachate, thereby facilitating subsequent treatment of the leachate.

[0010] Preferably, the coagulation sedimentation tank includes a reaction zone and a sedimentation zone, wherein 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 reagents such as coagulants and coagulants to react, and the sedimentation zone is used for sedimentation and separation of flocs generated after the reaction.

[0011] Preferably, the flotation tank includes a flotation reaction zone and a flotation contact zone, wherein 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 a coagulant aid to react, and the flotation contact zone is used for introducing high-pressure dissolved air water for flotation.

[0012] Preferably, the anaerobic digester is provided with a plurality of staggered baffles, one end of each baffle being connected to a side wall of the anaerobic digester and the other end forming a water passage between the baffles and the opposite side wall of the anaerobic digester. Anaerobic sludge is provided in the anaerobic digester. The baffles can extend the flow path of leachate within the anaerobic digester, thereby reducing the area of ​​the anaerobic digester while extending the anaerobic reaction time and improving the treatment efficiency of the anaerobic digester.

[0013] The anoxic tank includes interconnected anaerobic and anoxic zones. The anaerobic zone is connected to the anaerobic digester, which in turn is connected to the aerobic tank. Anaerobic sludge is present in both the anaerobic and anoxic zones. In the anaerobic zone, phosphorus-accumulating bacteria in the sludge release phosphorus and absorb lower fatty acids. In the anoxic zone, denitrifying bacteria in the sludge convert nitrates into nitrogen gas.

[0014] Preferably, the aerobic tank is provided with an aeration device and aerobic sludge.

[0015] Preferably, the aerobic tank is provided with a nitrification liquid reflux pump and a nitrification liquid reflux pipeline, and the nitrification liquid reflux pipeline is connected to the anoxic tank. The nitrification liquid after aerobic treatment in the aerobic tank can be pumped into the anoxic tank by the nitrification liquid reflux pump to continue denitrification.

[0016] Preferably, an aeration device and an MBR membrane assembly are provided in the MBR pool.

[0017] 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:

[0018] (1) The leachate enters the regulating tank for pH adjustment;

[0019] (2) The leachate after pH adjustment enters the coagulation sedimentation tank, where a compound coagulant and coagulant aid are added for coagulation and sedimentation;

[0020] (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;

[0021] (4) The effluent from the intermediate pool is sequentially treated by the anaerobic digester, the anoxic pool, and the aerobic pool;

[0022] (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.

[0023] In view of the water quality characteristics of leachate from garbage transfer stations, the present invention adopts a treatment process of coagulation-flotation-anaerobic digestion-anoxic-aerobic-MBR. In the coagulation sedimentation tank, suspended solids and oil in the leachate gradually form flocs under the action of a compound coagulant and a coagulant aid, accumulate into a thin mud layer, and slide down and discharge by its own gravity; the supernatant flows to the flotation tank. Under the action of flotation, tiny suspended solids in the leachate can adhere to the surface of 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 for biological anaerobic digestion reaction to remove organic matter; gas is generated during the anaerobic digestion process, which stirs the mud-water mixture, making the sludge suspended and increasing the mud-water contact area. Improve the 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 nitrate into nitrogen; the effluent from the anaerobic digester enters the aerobic tank, where the nitrifying bacteria in the aerobic sludge convert ammonia into nitrate, and heterotrophic microorganisms convert organic matter into water and carbon dioxide, and the 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, the mud and water are separated through the MBR membrane. The treated water finally enters the clear water tank and can meet the discharge standards.

[0024] This invention utilizes a combined physicochemical and biochemical treatment process, avoiding the drawbacks of a single process and achieving greater efficiency and cost-effectiveness while ensuring effluent quality. Compared to existing combined biochemical and physicochemical treatment processes for landfill leachate, this invention incorporates physicochemical treatment both before and after the biochemical treatment. The pre-biochemical treatment removes suspended solids and emulsified oil from the leachate, reducing the pressure of the biochemical treatment and preventing biochemical reactor clogging and filler contamination. The post-biochemical treatment utilizes MBR membranes for mud-water separation, ensuring effluent quality meets standards.

[0025] 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.

[0026] The present invention adds PAC and fly ash-based coagulant as a composite coagulant in a coagulation and sedimentation unit, and adds an organic polymer coagulant aid PAM for coagulant aid. PAC (polyaluminum chloride) is an inorganic polymer coagulant that forms multinuclear complex ions through hydroxyl bridging. It can instantly neutralize the negative charge of colloid particles in water, making the colloid particles unstable and rapidly coagulating. It further bridges to form flocs and quickly precipitates. 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. It has the characteristics of small particles, high porosity, and large specific surface area. It also has a large number of active sites such as Al and Si, which can undergo physical and chemical adsorption with pollutants. The present invention adds fly ash-based coagulant and PAC as a composite coagulant, which can integrate physical adsorption and chemical coagulation to better remove impurities such as colloidal particles, small suspended matter, and metal ions in the leachate. The organic polymer coagulant added in the present invention has a huge linear molecule, and the chain links on the molecule have a very strong adsorption effect on the colloidal particles in the leachate, forming a "colloid-polymer-colloid" flocculent body, which settles. 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, causing the colloid particles to stick together, increasing the adsorption force and aggregation ability between the suspended particles, and promoting coagulation and precipitation. In view of the complex pollutant characteristics of the leachate from the garbage transfer station, the present invention adopts a compound coagulant and a coagulant aid to work together. Compared with the addition of a single type of coagulant and coagulant aid, the alum flocs formed by the compound coagulant and coagulant aid working together are larger and denser, the flocs settle quickly, the leachate after treatment is clearly stratified, the water quality is clear, and the coagulation and precipitation effect is better.

[0027] Preferably, the preparation method of the fly ash-based coagulant is:

[0028] A) adding fly ash into a mixed solution of hydrochloric acid and sulfuric acid, soaking and washing the fly ash to obtain pickled fly ash;

[0029] B) reacting the fly ash after pickling with an epoxy silane coupling agent to obtain epoxy-modified fly ash;

[0030] C) reacting the epoxy-modified fly ash with sodium allyloxyhydroxypropyl sulfonate to obtain allyl-modified fly ash;

[0031] D) performing a hydrosilylation reaction on the allyl-modified fly ash and heptamethyltrisiloxane to obtain the fly ash-based coagulant.

[0032] To address the difficulty of separating and removing emulsified oil from leachate from garbage transfer stations, the present invention surface-modifies fly ash to produce a fly ash-based coagulant with excellent demulsification properties. First, the fly ash is acid-washed to increase its specific surface area and surface adsorption sites. The fly ash surface is then modified with an epoxy silane coupling agent to introduce epoxy groups. The allyloxyhydroxypropyl sulfonate is then attached to the fly ash surface through a ring-opening reaction between the epoxy groups on the fly ash surface and the hydroxyl groups in sodium allyloxyhydroxypropyl sulfonate, introducing unsaturated double bonds and sulfonate ions. Finally, an organosilicon compound is attached to the fly ash surface through a hydrosilylation reaction between the unsaturated double bonds and the silicon-hydrogen bonds in heptamethyltrisiloxane. 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 achieve 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 good pretreatment effect.

[0033] 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;

[0034] 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 3-5%, adding the fly ash obtained after acid washing to the silane coupling agent solution at a mass volume ratio of 1 g:30-50 mL, and stirring the reaction at 60-80° C. for 4-6 hours to obtain epoxy-modified fly ash;

[0035] 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 NaOH is added at 3-5% by mass of the mixed solvent. After stirring evenly, nitrogen is introduced at 60-70°C for 5-8 hours to obtain allyl-modified fly ash;

[0036] The reaction conditions of step D) are as follows: dispersing the allyl-modified fly ash in DMF, adding a chloroplatinic acid catalyst, and then adding heptamethyltrisiloxane. The mixture is stirred 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 the heptamethyltrisiloxane is 3-4:1.

[0037] 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.

[0038] 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.

[0039] Preferably, the reflux ratio of the nitrification solution in the aerobic tank is 100-500%.

[0040] Preferably, the dissolved oxygen in the MBR tank in step (5) is 1 to 3 mg / L.

[0041] Therefore, the present invention has the following beneficial effects:

[0042] (1) Combining physicochemical and biochemical processes to treat leachate from garbage transfer stations; in view of the water quality characteristics of leachate from garbage transfer stations, the present invention adopts a sewage treatment process that combines 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 effluent water; compared with the general biochemical + physicochemical combined treatment process for leachate from garbage, the present invention sets 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, reduces the pressure of the biochemical treatment, and avoids the problems of clogging 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 water quality meets the standard;

[0043] (2) The treatment of leachate from garbage transfer stations is optimized and integrated into an integrated device. In view of the characteristics of small and fluctuating water volume of leachate from garbage transfer stations and the dispersion 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 the cost of infrastructure investment. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] FIG1 is a schematic structural diagram of the integrated processing device of the present invention.

[0045] 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 screen, 13 aeration device, 14 nitrification liquid reflux pump. DETAILED DESCRIPTION

[0046] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0047] 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 all conventional methods in the art.

[0048] The experimental water in the present invention was taken from the leachate generated by a garbage transfer station in Zhejiang Province. The water quality was as follows: CODcr was 30-35 mg·mL -1 , BOD5 is 8-10 mg·mL -1 SS is 8-10 mg mL -1 , NH4 + -N is 0.6-0.7 mg·mL -1 , pH is 5.5-7.0; conventional water quality indicators are determined using national standard methods.

[0049] Overall embodiment:

[0050] An integrated leachate treatment device for a garbage transfer station, as shown in FIG1 , includes independently arranged treatment units and control units. The treatment units include a regulating tank 1, a coagulation and sedimentation tank 2, an air flotation tank 3, an intermediate water tank 4, an anaerobic digester 5, an anoxic tank 6, an aerobic tank 7, an MBR tank 8, and a clear water tank 9, which are separated and interconnected in sequence. The control area includes an equipment room 10 and a control room 11.

[0051] A basket grille 12 is provided at the entrance of the regulating tank;

[0052] The coagulation sedimentation tank includes a reaction zone 2.1 and a sedimentation zone 2.2 connected to each other. The reaction zone is connected to the regulating tank, and the sedimentation zone is connected to the flotation tank.

[0053] 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.

[0054] The anaerobic digester is provided with a plurality of staggered baffles 5.1, one end of each baffle being connected to a side wall of the anaerobic digester and the other end thereof forming a water passage between the baffles and the opposite side wall of the anaerobic digester. Anaerobic sludge is provided in the anaerobic digester.

[0055] 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 digester, and the anoxic zone is connected to the aerobic tank. Anaerobic sludge is provided in both the anaerobic zone and the anoxic zone.

[0056] The aerobic tank is provided with an aeration device 13 and aerobic sludge; the aerobic tank is provided with a nitrification liquid return pump 14 and a nitrification liquid return pipeline, and the nitrification liquid return pipeline is connected to the anaerobic zone in the anoxic tank;

[0057] The MBR pool is equipped with an aeration device and MBR membrane components.

[0058] The above-mentioned integrated treatment device is used to treat leachate from a garbage transfer station. The method includes the following steps:

[0059] (1) The leachate enters the regulating tank for pH adjustment, and the pH of the leachate is adjusted to 7.5-8.5;

[0060] (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 15-30 mg / L, the addition amount of the 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;

[0061] (3) The supernatant of the coagulation sedimentation tank enters the flotation tank, and 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, and the amount of PAM added is 10-40 mg / L. The pressure during the preparation of 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;

[0062] (4) The effluent from the intermediate water tank is biologically treated in sequence through the anaerobic digester, the anoxic tank, and the aerobic tank; 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; the nitrified liquid in the aerobic tank is returned to the anaerobic zone in the anoxic tank, and the return ratio is 100 to 500%;

[0063] (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 dissolved oxygen in the MBR pool is 1-3 mg / L;

[0064] Wherein, the preparation method of fly ash-based coagulant is:

[0065] A) adding fly ash to a mixed solution of hydrochloric acid and sulfuric acid, soaking and washing the mixture 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;

[0066] B) adding an epoxy silane coupling agent to xylene to prepare a silane coupling agent solution having 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 1 g:30-50 mL, and stirring the mixture at 60-80° C. for 4-6 hours to obtain epoxy-modified fly ash;

[0067] 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, wherein the mass ratio of epoxy-modified fly ash to the mixed solvent is 1:10-15, and then adding NaOH in an amount of 3-5% by mass of the mixed solvent, stirring uniformly, and then passing nitrogen gas at 60-70° C. for 5-8 hours to obtain allyl-modified fly ash;

[0068] D) dispersing the allyl-modified fly ash in DMF, adding a 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 the heptamethyltrisiloxane is 3-4:1.

[0069] Example 1:

[0070] The above-mentioned integrated treatment device is used to treat leachate from a garbage transfer station. The method includes the following steps:

[0071] (1) The leachate enters the regulating tank for pH adjustment, and the pH of the leachate is adjusted to 7.5-8.5;

[0072] (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 fly ash-based coagulant; the addition amount of PAC is 20 mg / L, the addition amount of fly ash-based coagulant is 10 mg / L; the coagulant aid is PAM, and the addition amount of PAM is 50 mg / L;

[0073] (3) The supernatant of the coagulation sedimentation tank enters the flotation tank, and 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, and 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;

[0074] (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 by aeration to 1.25±0.75 mg / L, and the hydraulic retention time in the aerobic tank is 11 hours; the nitrified liquid in the aerobic tank is returned to the anaerobic zone in the anoxic tank, and the return ratio is 250%;

[0075] (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 by aeration to 2±1 mg / L;

[0076] Wherein, the preparation method of fly ash-based coagulant is:

[0077] A) adding fly ash to a mixed solution of hydrochloric acid and sulfuric acid, soaking and washing the mixture 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;

[0078] 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 1 g:40 mL, and stirring the mixture at 70° C. for 5 hours to obtain epoxy-modified fly ash;

[0079] C) adding sodium allyloxyhydroxypropyl sulfonate and epoxy-modified fly ash in a volume 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 NaOH in an amount of 4% by mass of the mixed solvent. After stirring, nitrogen is passed through the mixture and the mixture is reacted at 65° C. for 6 hours to obtain allyl-modified fly ash;

[0080] D) dispersing the allyl-modified fly ash in DMF, adding 25 ppm of chloroplatinic acid catalyst, and then adding heptamethyltrisiloxane. The mixture was stirred and reacted 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 was 3.5:1.

[0081] Example 2:

[0082] The above-mentioned integrated treatment device is used to treat leachate from a garbage transfer station. The method includes the following steps:

[0083] (1) The leachate enters the regulating tank for pH adjustment, and the pH of the leachate is adjusted to 7.5-8.5;

[0084] (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, 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;

[0085] (3) The supernatant of the coagulation sedimentation tank enters the flotation tank, and 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, and 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;

[0086] (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 by aeration to 1.25±0.75 mg / L, and the hydraulic retention time in the aerobic tank is 11 hours; the nitrified liquid in the aerobic tank is returned to the anaerobic zone in the anoxic tank, and the return ratio is 250%;

[0087] (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 by aeration to 2±1 mg / L;

[0088] Wherein, the preparation method of fly ash-based coagulant is:

[0089] A) adding fly ash to a mixed solution of hydrochloric acid and sulfuric acid, soaking and washing the mixture 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;

[0090] B) adding silane coupling agent KH560 to xylene to prepare a 3% by mass silane coupling agent solution, adding fly ash obtained after acid washing to the silane coupling agent solution at a mass volume ratio of 1 g:50 mL, and stirring the mixture at 60° C. for 6 h to obtain epoxy-modified fly ash;

[0091] 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 the epoxy-modified fly ash to the mixed solvent is 1:10, and then adding NaOH in an amount of 3% by mass of the mixed solvent. After stirring, nitrogen is passed through the mixture and the mixture is reacted at 60° C. for 8 hours to obtain allyl-modified fly ash;

[0092] 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.

[0093] Example 3:

[0094] The above-mentioned integrated treatment device is used to treat leachate from a garbage transfer station. The method includes the following steps:

[0095] (1) The leachate enters the regulating tank for pH adjustment, and the pH of the leachate is adjusted to 8.5;

[0096] (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 fly ash-based coagulant; the addition amount of PAC is 30 mg / L, the addition amount of fly ash-based coagulant is 5 mg / L; the coagulant aid is PAM, and the addition amount of PAM is 35 mg / L;

[0097] (3) The supernatant of the coagulation sedimentation tank enters the flotation tank, and 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, and 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;

[0098] (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 by aeration to 1.25±0.75 mg / L, and the hydraulic retention time in the aerobic tank is 11 hours; the nitrified liquid in the aerobic tank is returned to the anaerobic zone in the anoxic tank, and the return ratio is 250%;

[0099] (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 by aeration to 2±1 mg / L;

[0100] Wherein, the preparation method of fly ash-based coagulant is:

[0101] A) adding fly ash to a mixed solution of hydrochloric acid and sulfuric acid, soaking and washing the mixture 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;

[0102] B) adding silane coupling agent KH560 to xylene to prepare a 5% by mass silane coupling agent solution, adding the fly ash obtained after acid washing to the silane coupling agent solution at a mass volume ratio of 1 g:30 mL, and stirring the mixture at 80° C. for 4 hours to obtain epoxy-modified fly ash;

[0103] 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, wherein 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. After stirring, nitrogen is passed through and the mixture is reacted at 70° C. for 5 hours to obtain allyl-modified fly ash;

[0104] 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.

[0105] Comparative Example 1:

[0106] 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. The rest is the same as in Example 1.

[0107] Comparative Example 2:

[0108] 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.

[0109] Comparative Example 3:

[0110] 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 and 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 h; the rest is the same as in Example 1.

[0111] Comparative Example 4:

[0112] The difference between Comparative Example 4 and Example 1 is that the preparation method of the fly ash-based coagulant is:

[0113] A) adding fly ash to a mixed solution of hydrochloric acid and sulfuric acid, soaking and washing the mixture 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;

[0114] 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 1 g:40 mL, and stirring the mixture at 70° C. for 5 hours to obtain epoxy-modified fly ash;

[0115] 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 NaOH in an amount of 4% by mass of the mixed solvent, stirring uniformly, and then passing nitrogen gas at 65° C. for 6 hours to obtain a fly ash-based coagulant;

[0116] The rest are the same as in Example 1.

[0117] Comparative Example 5:

[0118] A method for pretreating leachate from a garbage transfer station comprises the following steps:

[0119] (1) Add alkali to adjust the pH of the leachate to 7.5-8.5;

[0120] (2) adding a composite coagulant to the leachate obtained after pH adjustment to carry out a coagulation reaction, wherein the composite coagulant includes PAC, a fly ash-based coagulant, sodium allyloxyhydroxypropyl sulfonate, and heptamethyltrisiloxane; 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 heptamethyltrisiloxane is 1 mg / L;

[0121] (3) Adding organic polymer coagulant PAM to the leachate after coagulation reaction to react and precipitate, and the precipitated sludge is discharged; the addition amount of PAM is 50 mg / L;

[0122] (4) adding an organic polymer coagulant aid PAM to the supernatant after precipitation to react again, with the addition amount of PAM being 30 mg / L, and then introducing high-pressure dissolved air water and performing flotation. The pressure during the preparation of high-pressure dissolved air water is controlled at 0.5 MPa, and the introduced high-pressure dissolved air water is 10% of the mass of the water to be treated. After removing the surface scum, the pre-treated leachate is obtained;

[0123] Among them, the preparation method of fly ash-based coagulant is: adding fly ash to a mixed solution of hydrochloric acid and sulfuric acid, soaking and washing 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.

[0124] During the 30 days of stable operation, the water quality in the clear water tanks of the above embodiments and comparative examples was continuously monitored, and the results are shown in Table 1.

[0125] Table 1: Water quality test results of the clear water tank.

[0126] As can be seen from Table 1, the method of the present invention is used in Examples 1 to 3, and the final effluent CODcr can reach 500 mg·L -1 Below, BOD5 is 100 mg·L -1 Below, SS is 20 mg·L -1 Below, NH4 + -N is 40 mg·L -1 The following results achieved removal rates of 95%, 99% and 94% for organic matter, suspended solids and ammonia nitrogen, which means flexible, economical and efficient leachate treatment for garbage transfer stations.

[0127] In Comparative Example 1, only PAC was added as a coagulant, and in Comparative Example 2, only a fly ash-based coagulant was added. The coagulation effect was significantly reduced compared with the use of the compound 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 compound 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 fly ash surface; in Comparative Example 4, only the sulfonic acid group was modified on the fly ash surface without modifying the organosilicon group, and the demulsification performance was reduced, resulting in a decrease in the pretreatment effect, and thus 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 fly ash surface, and the treatment effect in the examples was also not achieved. This may be because when the sulfonic acid group and the organosilicon group are modified on the fly ash surface, their demulsification effect can cooperate with the adsorption effect of the fly ash, which is more conducive to oil-water separation.

Claims

1. An integrated treatment device for leachate from a garbage transfer station, characterized in that: The invention comprises an independently arranged processing unit and a control unit, wherein the processing unit comprises 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 with each other; and the control area comprises an equipment room (10) and a control room (11).

2. The integrated treatment device for leachate from a garbage transfer station according to claim 1 is characterized in that: 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.

3. The integrated treatment device for leachate from a garbage transfer station according to claim 1 or 2, 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.

4. The integrated treatment device for leachate from a garbage transfer station according to claim 1 is 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; anaerobic sludge is provided in the anaerobic digester.

5. The integrated treatment device for leachate from a garbage transfer station according to claim 1 is characterized in that: 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 arranged in both the anaerobic zone and the anoxic zone.

6. The integrated treatment device for leachate from a garbage transfer station according to claim 1 is characterized in that: The aerobic pool is provided with an aeration device (13) and aerobic sludge. The aerobic pool is also provided with a nitrification liquid return pump (14) and a nitrification liquid return pipeline. The nitrification liquid return pipeline is connected to the anoxic pool.

7. The integrated treatment device for leachate from a garbage transfer station according to claim 1 is characterized in that: The MBR pool is provided with an aeration device and an MBR membrane assembly.

8. A method for treating leachate from a garbage transfer station using the integrated treatment device according to any one of claims 1 to 7, characterized in that: The steps include: (1) The leachate enters the regulating tank for pH adjustment; (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; (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; (4) The effluent from the intermediate pool is sequentially treated by the anaerobic digestion tank, the anoxic tank, and the aerobic tank; (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.

9. The preparation method according to claim 8, characterized in that: The composite coagulant in step (2) includes PAC and a fly ash-based coagulant; 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 pickled fly ash; B) reacting the fly ash after pickling 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 the allyl-modified fly ash and heptamethyltrisiloxane to a hydrosilylation reaction to obtain the fly ash-based coagulant.

10. The preparation method according to claim 9, characterized in that: 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; 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; 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; 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.

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