An integrated device for leachate treatment at a waste transfer station

Abstract

This utility model discloses an integrated device for treating leachate from a waste transfer station, comprising a pretreatment unit, a biochemical unit, and a sludge treatment unit. The pretreatment unit includes a wastewater collection tank, a homogenization tank, and a dissolved air flotation (DAF) tank. The biochemical unit includes an anaerobic preparation tank, an anaerobic reactor, a two-stage AO reactor, and a secondary sedimentation tank. The sludge treatment unit includes a sludge storage tank and a screw press dewatering machine. The wastewater collection tank, homogenization tank, DAF tank, anaerobic preparation tank, anaerobic reactor, two-stage AO reactor, secondary sedimentation tank, sludge storage tank, and screw press dewatering machine are sequentially connected via pipelines. This utility model achieves full-volume treatment of leachate from waste transfer stations, and has advantages such as significant treatment effect, no secondary pollution, low operating cost, low energy consumption, and saving land area.

Description

Technical Field

[0001] This utility model relates to the field of leachate treatment technology, and in particular to an integrated device for leachate treatment in a waste transfer station. Background Technology

[0002] Waste transfer stations are a crucial link in the collection, transportation, and treatment of municipal solid waste, serving as vital hubs connecting waste collection and processing. During the transfer, compression, and temporary storage processes at these stations, a certain amount of leachate is generated. Statistics show that leachate production accounts for approximately 10% of the total waste volume. This leachate mainly consists of two parts: firstly, the wastewater generated during waste compression, with the following characteristics: pH between 2 and 4, conductivity 12000-18000 Us / cm, SS 5000-8000 mg / L, COD around 40000 mg / L, TN 1000 mg / L, ammonia nitrogen around 300 mg / L, TP 100-120 mg / L, chloride ion content 3000-4000 mg / L, sulfate content 300-500 mg / L, and TDS around 10000 mg / L. The second type is flushing wastewater, which mainly comes from cleaning garbage cans, garbage trucks, and the ground. The water quality of this wastewater is as follows: pH between 5 and 7, conductivity 1000 Us / cm, SS 200 mg / L, COD around 1000 mg / L, TN 15-30 mg / L, ammonia nitrogen around 10-20 mg / L, TP around 5 mg / L, chloride ion content 100 mg / L, and sulfate content around 10 mg / L. The mixture of these two wastewater streams becomes landfill leachate, and therefore, the characteristics of landfill leachate wastewater are as follows:

[0003] 1. The concentration of pollutants is relatively high, with the main pollutants being COD, SS, ammonia nitrogen, total nitrogen, and total phosphorus;

[0004] 2. The quantity and quality of water are unstable and vary widely;

[0005] 3. The wastewater contains a lot of floating oil and suspended solids, requiring a great deal of pretreatment to reduce the impact of water volume fluctuations and floating oil and suspended solids on the subsequent treatment system;

[0006] 4. The wastewater contains a large amount of chloride ions, which are highly corrosive, requiring high corrosion protection for the equipment and devices.

[0007] Regarding the aforementioned leachate water quality, current treatment methods mainly consist of three types: physical, chemical, and biological. Physical methods primarily include filtration, adsorption, and membrane separation. Filtration removes suspended solids (SS), colloids, and some large organic molecules from the leachate through physical sieving or retention, but it has limited effectiveness in removing dissolved COD and ammonia nitrogen. Adsorption utilizes the porous structure and surface activity of adsorbents to remove pollutants through physical or chemical adsorption, but it has low efficiency for treating high concentrations of pollutants, high adsorbent regeneration costs, and limited adsorption capacity. Membrane separation utilizes the selective permeability of membranes to separate pollutants under pressure or concentration gradients, but severe membrane fouling necessitates regular chemical cleaning, resulting in high investment and operating costs, and the concentrate is difficult to treat.

[0008] Chemical methods remove pollutants from water bodies using chemical means, mainly including coagulation and sedimentation, oxidation-reduction methods, and adsorption. Coagulation and sedimentation involves adding chemical agents to cause pollutants to agglomerate into flocs, facilitating separation. While this method is simple and quick to implement, the use of chemical agents carries certain risks and may cause secondary pollution, making it less safe. Oxidation-reduction methods include Fenton oxidation and ozone oxidation. Fenton oxidation has high costs for subsequent sludge treatment, while ozone oxidation has high energy consumption (10-20 kWh / kgO3), resulting in even higher operating costs. Adsorption utilizes the active sites on the surface of adsorbents to adsorb pollutants, but adsorbent regeneration costs are high, and adsorbents are easily saturated.

[0009] Traditional physical and chemical methods are expensive, energy-intensive, prone to secondary pollution, and unable to fundamentally solve the problem. Biological methods, on the other hand, offer significant advantages such as high treatment efficiency, no secondary pollution, low operating costs, low energy consumption, and space-saving design, making them a popular choice for leachate treatment at waste transfer stations. Common technologies include UASB+AO+MBR, air flotation+two-stage AO+MBR, AO+ultrafiltration+nanofiltration, MABR+MBBR+MBR, and Fenton+SBR+activated carbon adsorption. However, technologies such as ultrafiltration, nanofiltration, MABR, and MBBR produce a certain amount of concentrate, which is more difficult to treat and has higher processing costs, preventing the full-scale treatment of leachate from waste transfer stations. Utility Model Content

[0010] To solve the above-mentioned technical problems, this utility model designs an integrated device for leachate treatment in waste transfer stations.

[0011] The present invention adopts the following technical solution:

[0012] An integrated leachate treatment device for a waste transfer station includes a pretreatment unit, a biochemical unit, and a sludge treatment unit. The pretreatment unit includes a wastewater collection tank, a homogenization tank, and an air flotation tank. The biochemical unit includes an anaerobic preparation tank, an anaerobic reactor, a two-stage AO reactor, and a secondary sedimentation tank. The sludge treatment unit includes a sludge storage tank and a screw press dewatering machine. The wastewater collection tank, homogenization tank, air flotation tank, anaerobic preparation tank, anaerobic reactor, two-stage AO reactor, secondary sedimentation tank, sludge storage tank, and screw press dewatering machine are connected sequentially through pipelines.

[0013] Preferably, a sewage lift pump is installed on the pipeline connecting the wastewater collection tank and the homogenization tank.

[0014] Preferably, the homogenizing tank is equipped with a homogenizing tank agitator and a pH meter.

[0015] Preferably, the flotation tank and the anaerobic preparation tank are connected by a pipeline to an intermediate water tank, which is connected by a sewage return pump and then back to the homogenization tank. A level gauge is installed in the intermediate water tank.

[0016] Preferably, the bottom of the anaerobic preparation tank is connected back to the anaerobic preparation tank via a return pipe and a circulating water pump.

[0017] Preferably, the gas outlet of the anaerobic reactor is connected to a biogas burner via a pipeline, the bottom of the anaerobic preparation tank is connected to the bottom of the anaerobic reactor via a pipeline and an anaerobic preparation tank effluent pump, the bottom of the anaerobic reactor is equipped with an anaerobic reactor stepping water system, and a three-phase separator is installed inside the anaerobic reactor.

[0018] Preferably, the two-stage AO includes a first-stage anoxic tank, a first-stage aerobic tank, a second-stage anoxic tank, and a second-stage aerobic tank connected in sequence. Anoxic tank agitators and anoxic tank level gauges are arranged in the first-stage and second-stage anoxic tanks. Anoxic tank packing is arranged in the first-stage and second-stage anoxic tanks. Aerobic tank packing is arranged in the first-stage and second-stage aerobic tanks.

[0019] Preferably, the primary anoxic tank and the primary aerobic tank are connected by a return pipe and a mixed liquor return pump, and aerobic tank aerators are arranged in the primary aerobic tank and the secondary aerobic tank.

[0020] Preferably, the secondary sedimentation tank is connected back to the primary anoxic tank via a return pipe and a sludge return pump.

[0021] Preferably, the sludge storage tank is equipped with a sludge level gauge and a sludge storage tank agitator, and a sludge screw pump is installed on the pipeline between the sludge storage tank and the screw press dewatering machine.

[0022] The beneficial effects of this utility model are as follows: This utility model designs an integrated device for treating leachate from a waste transfer station, realizing the full-scale treatment of leachate from the waste transfer station. The dissolved air flotation (DAF) tank, through the addition of flocculants and liquid alkali to induce flocculation and adjust the pH, removes floating oil, suspended solids (SS), and some COD under the action of DAF. In the anaerobic reactor, the organic matter is converted into CO2 and CH4 through the decomposition action of microorganisms in the sludge layer. Biogas is separated by a three-phase separator and then incinerated by a matching biogas burner. In the primary anoxic tank, denitrifying bacteria convert nitrate nitrogen into nitrogen gas, achieving denitrification and reducing the concentration of nitrate nitrogen and COD. The physicochemical sludge produced by DAF is harmless and can be sent to a sludge storage tank. The biological sludge and physicochemical sludge are pumped into a screw press dewatering machine for dewatering before being transported off-site. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of this utility model;

[0024] In the diagram: 1. Wastewater collection tank; 2. Homogenizing tank; 3. Flotation tank; 4. Intermediate water tank; 5. Anaerobic preparation tank; 6. Anaerobic reactor; 7. Primary anoxic tank; 8. Primary aerobic tank; 9. Secondary anoxic tank; 10. Secondary aerobic tank; 11. Secondary sedimentation tank; 12. Sludge storage tank; 13. Biogas burner; A. Wastewater lift pump; B. Homogenizing tank agitator; C. pH meter; D. Wastewater return pump; E. Liquid... Level gauge, F, circulating water pump, G, anaerobic preparation tank effluent pump, H, anaerobic reactor step-water system, I, three-phase separator, J, anoxic tank agitator, K, anoxic tank level gauge, L, aerobic tank packing, M, anoxic tank packing, N, mixed liquor return pump, O, aerobic tank aerator, P, sludge return pump, Q, sludge storage tank level gauge, R, sludge storage tank agitator, S, sludge screw pump, T, screw press dewatering machine. Detailed Implementation

[0025] The technical solution of this utility model will be further described in detail below through specific embodiments and with reference to the accompanying drawings:

[0026] Example: Figure 1 As shown, an integrated leachate treatment device for a waste transfer station includes a pretreatment unit, a biochemical unit, and a sludge treatment unit. The pretreatment unit includes a wastewater collection tank 1, a homogenizing tank 2, and an air flotation tank 3. The biochemical unit includes an anaerobic preparation tank 5, an anaerobic reactor 6, a two-stage AO reactor, and a secondary sedimentation tank 11. The sludge treatment unit includes a sludge storage tank 12 and a screw press dewatering machine T. The wastewater collection tank, homogenizing tank, air flotation tank, anaerobic preparation tank, anaerobic reactor, two-stage AO reactor, secondary sedimentation tank, sludge storage tank, and screw press dewatering machine are connected sequentially through pipelines.

[0027] A sewage lift pump A is installed on the pipeline connecting the wastewater collection tank and the homogenization tank. A homogenization tank agitator B and a pH meter C are installed inside the homogenization tank.

[0028] An intermediate water tank 4 is connected to the flotation tank and the anaerobic preparation tank by a pipeline. The intermediate water tank is connected to the sewage return pump D by a pipeline and then back to the homogenization tank. A level gauge E is installed in the intermediate water tank.

[0029] The bottom of the anaerobic preparation tank is connected back to the anaerobic preparation tank via a return pipe and a circulating water pump F.

[0030] The gas outlet of the anaerobic reactor is connected to the biogas burner 13 through a pipeline. The bottom of the anaerobic preparation tank is connected to the bottom of the anaerobic reactor through a pipeline and the anaerobic preparation tank effluent pump G. The bottom of the anaerobic reactor is equipped with an anaerobic reactor stepping water system H. A three-phase separator I is installed inside the anaerobic reactor.

[0031] The two-stage AO consists of a first-stage anoxic tank 7, a first-stage aerobic tank 8, a second-stage anoxic tank 9, and a second-stage aerobic tank 10 connected in sequence. Anoxic tank agitators J and anoxic tank level gauges K are arranged in the first-stage and second-stage anoxic tanks. Anoxic tank packing material M is arranged in the first-stage and second-stage anoxic tanks. Aerobic tank packing material L is arranged in the first-stage and second-stage aerobic tanks.

[0032] The primary anoxic tank and the primary aerobic tank are connected by a return pipe and a mixed liquor return pump N. Aerobic tank aerators O are arranged in the primary aerobic tank and the secondary aerobic tank.

[0033] The secondary sedimentation tank is connected back to the primary anoxic tank via a return pipe and a sludge return pump P.

[0034] The sludge storage tank is equipped with a sludge level gauge Q and a sludge agitator R. A sludge screw pump S is installed on the pipeline between the sludge storage tank and the screw press dewatering machine.

[0035] In the application of this invention, the quality and quantity of wastewater from pressing and rinsing vary significantly. To facilitate operation and save on investment and operating costs, a wastewater collection tank is required. Wastewater is pumped from the collection tank to a homogenization tank for quality and quantity adjustment, then enters a flotation tank. Here, flocculants and liquid alkali are added to induce flocculation and adjust the pH. Under flotation, floating oil, suspended solids (SS), and some COD are removed. Finally, the wastewater enters an anaerobic preparation tank, where it is thoroughly mixed with the anaerobic effluent and then flows from the bottom of the anaerobic reactor into the anaerobic sludge bed. The sludge is evenly distributed within the anaerobic reactor via a step-water system and thoroughly mixed and contacted within the sludge layer. Through the decomposition by microorganisms in the sludge layer, organic matter is converted into CO2 and CH4. Biogas is separated by a three-phase separator and then incinerated by a matching biogas burner. After being separated by the three-phase separator, the sludge slides back into the anaerobic reaction zone along the inclined wall, causing a large accumulation of sludge in the reaction zone. The effluent, separated from the sludge, overflows from the top of the sedimentation zone's overflow weir and is discharged from the anaerobic reactor. The effluent from the anaerobic system flows by gravity into the subsequent two-stage A / O biological system, mixing with the mixed liquor returned from the first-stage aerobic tank. In the first-stage anoxic tank, denitrifying bacteria convert nitrate nitrogen into nitrogen gas, achieving denitrification and reducing nitrate nitrogen and COD concentrations. The effluent from the first-stage anoxic tank flows by gravity into the first-stage aerobic tank, where nitrification and aerobic phosphorus uptake occur through the action of nitrifying bacteria and polyphosphate-accumulating bacteria, consuming COD. The effluent from the first-stage aerobic tank flows by gravity into the second-stage A / O tank, where the operation of the first-stage A / O system is repeated to further achieve denitrification. The effluent from the two-stage A / O system flows into the secondary sedimentation tank for sludge-water separation. The supernatant flows into the discharge tank, and the settled sludge is returned via a sludge return pump to ensure stable sludge concentration and activity in the two-stage A / O system. Some excess sludge is discharged into a sludge storage tank. The sludge produced by the anaerobic reactor requires no treatment and has economic value. Under normal operating conditions, the two-stage A / O system requires daily or periodic sludge discharge, with the discharged aerobic excess sludge entering the sludge storage tank. The physicochemical sludge produced by air flotation is harmless and can be sent to the sludge storage tank. Biological sludge and physicochemical sludge are pumped into a screw press dewatering machine for dewatering. This process requires PAM conditioning, and the dewatered sludge cake is transported off-site for disposal.

[0036] In the dissolved air flotation (DAF) tank, the dosage of PAC is 40-60 mg / L, PAM is 1-5 mg / L, and liquid alkali (32%) is 100-150 mg / L. In the sludge storage tank, the dosage of PAM is 20-30 mg / L of wet sludge.

[0037] In the anoxic tank, DO < 0.5 mg / L; in the aerobic tank, DO > 2 mg / L.

[0038] The embodiments described above are merely preferred solutions of this utility model and are not intended to limit this utility model in any way. Other variations and modifications are possible without departing from the technical solutions described in the claims.

Claims

1. A waste transfer station leachate treatment integrated device, characterized in that, It includes a pretreatment unit, a biochemical unit, and a sludge treatment unit. The pretreatment unit includes a wastewater collection tank, a homogenization tank, and an air flotation tank. The biochemical unit includes an anaerobic preparation tank, an anaerobic reactor, a two-stage AO reactor, and a secondary sedimentation tank. The sludge treatment unit includes a sludge storage tank and a screw press dewatering machine. The wastewater collection tank, homogenization tank, air flotation tank, anaerobic preparation tank, anaerobic reactor, two-stage AO reactor, secondary sedimentation tank, sludge storage tank, and screw press dewatering machine are connected sequentially through pipelines.

2. The integrated device for leachate treatment of a waste transfer station according to claim 1, characterized in that, A sewage lift pump is installed on the pipeline connecting the wastewater collection tank and the homogenization tank.

3. The integrated leachate treatment device for a waste transfer station according to claim 1, characterized in that, The homogenization tank is equipped with a homogenization tank agitator and a pH meter.

4. The integrated device for leachate treatment of a waste transfer station according to claim 1, characterized in that, The air flotation tank and the anaerobic preparation tank are connected by a pipeline to an intermediate water tank. The intermediate water tank is connected by a sewage return pump and then back to the homogenization tank. A level gauge is installed in the intermediate water tank.

5. The integrated device for leachate treatment of a waste transfer station according to claim 1, characterized in that, The bottom of the anaerobic preparation tank is connected back to the anaerobic preparation tank via a return pipe and a circulating water pump.

6. The integrated device for leachate treatment of a waste transfer station according to claim 1, characterized in that, The gas outlet of the anaerobic reactor is connected to the biogas burner through a pipeline. The bottom of the anaerobic preparation tank is connected to the bottom of the anaerobic reactor through a pipeline and the anaerobic preparation tank effluent pump. An anaerobic reactor stepping water system is installed at the bottom of the anaerobic reactor. A three-phase separator is installed inside the anaerobic reactor.

7. The integrated device for leachate treatment of a waste transfer station according to claim 1, characterized in that, The two-stage AO includes a first-stage anoxic tank, a first-stage aerobic tank, a second-stage anoxic tank, and a second-stage aerobic tank connected in sequence. The first-stage and second-stage anoxic tanks are equipped with anoxic tank agitators and anoxic tank level gauges. The first-stage and second-stage anoxic tanks are equipped with anoxic tank packing materials. The first-stage and second-stage aerobic tanks are equipped with aerobic tank packing materials.

8. The integrated leachate treatment device for a waste transfer station according to claim 7, characterized in that, The primary anoxic tank and the primary aerobic tank are connected by a return pipe and a mixed liquor return pump. Aerobic tank aerators are arranged in the primary aerobic tank and the secondary aerobic tank.

9. The integrated leachate treatment device for a waste transfer station according to claim 7, characterized in that, The secondary sedimentation tank is connected back to the primary anoxic tank via a return pipe and a sludge return pump.

10. The integrated leachate treatment device for a waste transfer station according to claim 7, characterized in that, The sludge storage tank is equipped with a sludge level gauge and a sludge agitator, and a sludge screw pump is installed on the pipeline between the sludge storage tank and the screw press dewatering machine.

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