CN100406399C - A method and system for treating leachate in domestic waste landfill - Google Patents

Abstract

The invention discloses a treatment method for leachate of domestic waste landfill, which is composed of ammonia blow-off, coagulation sedimentation, biological treatment and membrane treatment, including: blowing off the leachate with ammonia, degrading the ammonia in the landfill leachate Ammonia nitrogen; coagulation and sedimentation treatment of the leachate after ammonia stripping to remove the biodegradability of organic matter and suspended matter; biochemical treatment of coagulation and sedimentation treated sewage; membrane treatment of biochemically treated sewage. The invention also discloses a system for treating leachate using the above method, including a regulating tank, a pre-aeration tank, a primary settling tank, an ammonia stripping tower, an intermediate water tank, a secondary settling tank, an ^A2 /O The process unit, final sedimentation tank, temporary storage tank, membrane treatment system and clear water tank, primary sedimentation tank, secondary sedimentation tank, final sedimentation tank and membrane treatment system are connected to the sludge tank through pipelines, and the sludge tank is connected with a filter press, The ammonia stripping tower is connected with the absorption tower. The invention can be widely used in landfill leachate engineering treatment.

Description

A method and system for treating leachate in domestic waste landfill

technical field

The invention relates to a method and system for treating landfill leachate by combining physical and chemical treatment with biological treatment and membrane technology, and belongs to the field of new environmental protection technologies.

Background technique

Landfill leachate is a kind of high-concentration organic wastewater that is difficult to treat. It mainly comes from the following three aspects: (1) natural rainfall and runoff in the landfill; (2) the original water content of the garbage itself; (3) in the landfill. The water produced by the anaerobic decomposition of microorganisms after sanitary landfill. When the water content of the garbage is 47%, each ton of garbage can produce 0.0722 tons of leachate. Biochemical reactions produce far less water. Atmospheric precipitation is concentrated, short-term and repetitive, and the leachate formed by the precipitation that has not been drained in time seeps through the garbage layer accounts for the vast majority of the total. At the same time, due to the complex composition of the garbage and the high content of organic matter, reactions such as decomposition, dissolution, and fermentation occur after landfilling, and the leachate contains a large amount of organic matter, nitrogen and phosphorus substances, and a variety of heavy metals with excessive content, among which CODcr, BOD _5. Heavy metals, ammonia nitrogen and salt content are all very high. Moreover, the biodegradability of landfill leachate is poor, organic matter with large molecular weight dominates, the proportion of microbial nutrient elements is out of balance, and it has certain toxicity. Specifically, landfill leachate has the following characteristics:

1. The leachate is light brown or dark in color and has a strong rancid smell;

2. The initial landfill leachate pH is 6-7, and as time goes by, the pH is 7-8;

3. The concentration of BOD and COD is high, up to tens of thousands of units, much higher than that of urban sewage. With the increase of time and microbial activity, the BOD ₅ in the leachate also gradually increased, reached the peak in 6 months to 2 and a half years, then gradually decreased, and the landfill was stable in 6-15 years, while the COD _cr value, the initial stage of landfill Slightly lower than BOD ₅ , but over time, BOD ₅ drops sharply, while COD _cr drops slowly;

4. The concentration of nitrogen compounds is high, mainly ammonia nitrogen, generally at 1500mg/l. Although the content of ammonia nitrogen is high, it lacks phosphorus, which brings certain difficulties to biological treatment;

5. The composition is complex, and there are many types of organic pollutants, including naphthalene, chlorinated aromatic compounds, phosphates, phthalates, phenolic compounds and aniline compounds that are difficult to biodegrade; Microorganisms produce inhibitory heavy metal ions.

Therefore, the focus of landfill leachate treatment is the treatment of COD _cr and ammonia nitrogen, especially the treatment of ammonia nitrogen.

In the prior art, there are many methods for treating domestic waste landfill leachate, generally including physical and chemical methods, biological methods and land methods.

Physical and chemical methods mainly include activated carbon adsorption, chemical coagulation precipitation, chemical oxidation, chemical reduction, density separation, membrane dialysis, gas and wet oxidation and other methods. Pretreatment of leachate with physical and chemical methods can effectively remove COD, ammonia nitrogen, heavy metal ions, chroma, etc. in the leachate, increase BOD ₅ /COD _cr , improve the biodegradability of the leachate, and minimize heavy metals and NH The inhibitory effect of ₃ -N on microorganisms reduces the load, creates good conditions for its subsequent biological treatment process, and saves treatment costs. Compared with the biological method, the physical chemical method is not affected by the change of water quality and quantity, and the effluent water quality is stable, especially for the leachate with a small BOD ₅ /COD _cr (0.07-0.20) that is difficult to treat biologically. Treatment costs are high, but necessary for the removal of some pollutants.

Biological methods mainly include activated sludge method, biological contact oxidation method, biological turntable method, A ² /O, SBR, biological fluidized bed, oxidation pond, soil treatment method, leachate recharge method, etc. Among them, the activated sludge process (oxidation pond and SBR) process is relatively stable and mature, but it occupies a large area, high power consumption, complex operation management, and long sludge cultivation time, especially during factory maintenance. live, the sewage treatment runs again and the sludge must be recultivated.

Land treatment mainly removes suspended solids and dissolved components in the filtrate through the filtration of soil particles, ion exchange adsorption and precipitation, and transforms organic matter and ammonia chloride in the leachate through the action of microorganisms in the soil. Microbial treatment of pollutants in the soil The ability is stronger than the corresponding microorganisms in the fluid, so the land method also has a good effect on treating landfill leachate. At present, the land methods used for landfill leachate treatment mainly include recharge method and constructed wetland method.

Due to the complex components of the leachate water quality, it is impossible to meet the first-level standard of the design with a single biological treatment or physical and chemical treatment, and it will cause uneconomical treatment costs. Therefore, it is necessary to consider the synergistic effect of multiple methods. In addition, high concentration of ammonia nitrogen (above 1000 mg/l) can significantly inhibit anaerobic microorganisms, making the anaerobic removal efficiency low.

Contents of the invention

The invention provides a landfill leachate treatment method, which is realized by combining ammonia stripping, coagulation sedimentation, biological treatment and membrane technology.

The invention also provides a treatment system for implementing the above method, which can treat the landfill leachate and discharge it up to the standard.

A method for treating leachate from domestic waste landfills, the method is composed of ammonia stripping, coagulation sedimentation, biological treatment and membrane treatment, and mainly includes the following steps:

(1) Perform ammonia stripping on the leachate to degrade the ammonia nitrogen in the landfill leachate;

(2) Carry out coagulation and precipitation treatment to the leachate after ammonia stripping, remove the biodegradability of organic matter and suspended matter;

(3) Carry out biochemical treatment to the sewage treated by coagulation and sedimentation;

(4) Membrane treatment is performed on the biochemically treated sewage.

The ammonia stripping treatment process adopts air stripping method.

The biochemical treatment process adopts the A ² /O process, and the A ² /O process is composed of anaerobic microbial treatment section, anoxic microbial treatment section and aerobic microbial treatment section.

The membrane treatment process uses a reverse osmosis process to perform advanced treatment on the leachate after biochemical treatment.

A system for treating leachate from domestic waste landfills, the system includes a regulating tank, a pre-aeration tank, a primary settling tank, an ammonia stripping tower, an intermediate water tank, a secondary settling tank, and an A ² /O Process unit, final settling tank, temporary storage tank, membrane treatment system and clean water tank, among which, primary settling tank, secondary settling tank, final settling tank and membrane treatment system are connected to the sludge tank through pipelines, and the sludge tank is connected with press filter machine, the ammonia stripping tower is connected to the absorption tower.

The primary sedimentation tank includes a pH adjustment tank, a vertical flow sedimentation tank and an intermediate tank.

The A ² /O process device is composed of an upflow anaerobic bed and an A/O pool connected in sequence through pipelines, and the A/O pool includes an anoxic pool and an aerobic pool.

The membrane treatment system includes a water inlet box, a booster pump, a mechanical filter and a reverse osmosis device connected in sequence by pipelines.

The reverse osmosis device is composed of a security filter, a first-stage high-pressure pump, a first-stage reverse osmosis, a second-stage high-pressure pump, a second-stage reverse osmosis and an alkali dosing device.

The process flow of the present invention is as follows: the leachate from the landfill is collected by the collection system, concentrated in the adjustment tank to adjust the water quality and water quantity; Adjust the PH value of the leachate to above 10; the effluent from the PH adjustment tank enters the sedimentation tank in the primary sedimentation tank, during which polymer PAM is added to make the emulsified sediment flocculate and agglomerate through the polymer to form a macromolecular precipitate , to accelerate the solid-liquid separation of precipitation; the effluent from the sedimentation tank enters the intermediate pool in the primary sedimentation tank, and the water in the intermediate pool is lifted by the pump into the stripping tower for blowing off nitrogen. area, which is conducive to the removal of ammonia nitrogen; the ammonia nitrogen blown out is absorbed by the absorption tower with concentrated sulfuric acid to form ammonium sulfate for recycling, so as to avoid the secondary pollution caused by the direct discharge of ammonia to the atmosphere; pool, add coagulant, remove some organic matter through isoelectric point flocculation, and increase the ratio of leachate BOD/COD; then enter the A ² /O process device, and treat the leachate and activated sludge through an upflow anaerobic bed Fully mix and decompose macromolecular organic matter by anaerobic bacteria to convert it into small molecular organic matter; the anoxic pool and aerobic pool in the A/O pool part hang combined fillers, and the anoxic pool is aerated and stirred through large pores to make the underwater activity The sludge and leachate are fully mixed, and some ammonia nitrogen is removed by nitrification and denitrification through the backflow of the leachate in the aerobic pool; the aerobic pool uses a three-leaf Roots blower and a microporous aeration head for aeration, and each pool operates independently , microbial phase separation, high treatment efficiency; the leachate after biological treatment enters the final sedimentation tank to settle sludge, and the effluent of the final sedimentation tank is subjected to sedimentation and oxidation disinfection treatment through the membrane treatment system to ensure that the leachate discharge meets the standard; among them, the primary sedimentation tank, The sludge from the secondary sedimentation tank, the final sedimentation tank and the remaining sludge from membrane treatment enter the sludge tank and are squeezed dry by the filter press before being sent to the landfill for treatment. The leachate that does not meet the discharge standard after membrane treatment is returned to the adjustment tank .

The present invention has the following advantages:

(1) Through ammonia stripping, the toxicity of ammonia to subsequent biochemical treatment can be reduced, and with subsequent nitrification and denitrification denitrification, ammonia nitrogen can be discharged close to the standard.

(2) Coagulation and sedimentation pretreatment, less investment, stable effect and easy management.

(3) The A ² /O process is selected, and the combined filler is hung in the pool, the process is stable in operation and easy to operate and manage.

(4) The A ² /O process can achieve biological nitrogen removal by controlling the return flow of sludge and mixed liquor.

(5) The amount of sludge produced is small, generally around 1-3%.

(6) The deep treatment process of the reverse osmosis device is advanced, which can completely solve the pollution problem and is easy to manage.

(7) Wide application, suitable for 50-800T/d landfill leachate engineering treatment.

Description of drawings

Fig. 1 is a schematic flow chart of the system structure of the present invention.

Detailed ways

A method for treating leachate from domestic waste landfills, the method is composed of ammonia stripping, coagulation sedimentation, biological treatment and membrane treatment, and mainly includes the following steps:

(1) Perform ammonia stripping on the leachate to degrade the ammonia nitrogen in the landfill leachate;

(2) Carry out coagulation and precipitation treatment to the leachate after ammonia stripping, remove the biodegradability of organic matter and suspended matter;

(3) Carry out biochemical treatment to the sewage treated by coagulation and sedimentation;

(4) Membrane treatment is performed on the biochemically treated sewage.

Process control of the present invention is described as follows:

1. Process control of primary sedimentation tank

The front reaction tank of the primary sedimentation tank is composed of three parts: reaction, coagulation and sedimentation. The prepared milk of lime is put into the fast reaction tank. The reaction tank has a built-in mixer to fully mix the leachate and the agent. Because the reaction speed of lime is relatively slow, it can quickly The effluent from the reaction tank enters the coagulation tank, and is stirred and reacted again by a slow mixer to avoid fluctuations in the pH value of the water quality produced in the subsequent process; due to the formation of CaCO ₃ and various hydroxide precipitations, in order to prevent micro flocs from entering the stripping tower, The polymer flocculant PAM is added into the coagulation tank, and after agglomeration and precipitation treatment, the molecular weight of the polymer flocculant is about 8 million, and the concentration of the agent is 1/1000. For the dosage of lime, when the pH value of the leachate is between 7-8, the dosage of lime is 9-12g/L, and the dosage of polymer flocculant is 2-6PPm; To avoid scaling, the sludge in the settling tank should be discharged in time every day. In order to avoid the agglomeration of CaCO ₃ and various hydroxide deposits, resulting in poor sludge discharge, the settling tank should be cleaned regularly to avoid scaling on the wall .

2. Ammonia stripping process control:

For landfill leachate with high ammonia nitrogen, the more economical and effective pre-treatment method is to use the gas stripping method for pre-treatment. By adjusting the pH value of the wastewater to about 10.5, a large amount of free ammonia is generated and then stripped and removed. At present, there are two methods of blowing off: air blowing off and steam blowing off, but steam blowing off requires a boiler, complex equipment, heavy engineering maintenance workload, and high operating costs. Therefore, the present invention selects the air stripping method for use, and the deammonification efficiency of the air stripping method is affected by the following elements:

(1) temperature

The general average air temperature of the present invention is at 15 DEG C-16 DEG C, and the average air temperature in summer is about 25 DEG C, and the blow-off of ammonia nitrogen is in the more suitable air temperature; Therefore, in order to improve the removal efficiency, the following methods should be adopted in winter to increase the removal rate of ammonia nitrogen: ① Increase the PH value of wastewater, which should be around 10 in summer and around 11 in winter. ②The shell of the pool is treated with foam plastic for heat preservation.

(2) Gas-liquid ratio

Under normal circumstances, with the increase of the gas-liquid ratio, the stripping efficiency of ammonia nitrogen will gradually increase, and an excessively high gas-liquid ratio will increase energy consumption, and in addition, part of the liquid will be taken out from the defogging plate, making recovery The sulfuric acid content of ammonia increases. According to the parameters of our company in the stripping test, and considering the energy consumption, the gas-liquid ratio should be controlled at about 2000-2500.

(3) pH adjustment

For the pH adjustment of air stripping, sodium hydroxide or lime can be used. However, considering the amount of dosing and operating costs of post-blowing treatment, the PH is adjusted by adding lime. Because the waste water from general landfills contains HCO ₃ ^-ions , and adding lime can make most of the carbonate ions precipitate out as CaCO ₃ , while sodium hydroxide can only remove part of it.

(4) Scaling problem of adding lime

A large amount of packing is built in the stripping tower, so that the liquid forms a liquid water film on the surface of the packing, and when the upstream gas passes through the surface of the packing, it performs gas-liquid exchange to facilitate the stripping of ammonia nitrogen. Due to the high pH value of the wastewater, a large amount of CaCO ₃ , Mg(OH) ₂ and heavy metal hydroxide precipitates are formed, most of which can be removed in the sedimentation tank, and a small part of the micro flocs enter the packed tower with the water flow, and bond On the packing, over time, it is easy to cause the packing to be blocked. Solution: ① The pre-sedimentation tank uses a polymer flocculant for coagulation to reduce microcoagulation entering the stripping tower. ② Add a small amount of Na ₂ CO ₃ to the lime to reduce the deposition of calcium ions.

3. Secondary sedimentation tank process control

The pH value of the landfill leachate effluent from the deamination tower is between 8.5 and 9.5, and the concentration of HCO ₃ ^- ions in the water is reduced due to the formation of CaCO ₃ precipitates. The coagulation sedimentation tank is composed of three parts: reaction, coagulation and sedimentation, during which KB composite flocculant is added for reaction, the dosing amount is 2g/L, and the coagulant aid is 4.0PPm. However, the dosing amount must be adjusted at any time according to the leachate water quality.

4. A ² /O process control

The leachate biochemical treatment subject of the present invention adopts the A ² /O process: "anaerobic + anoxic + aerobic" has the following characteristics:

The anaerobic reaction is dominated by anaerobic microorganisms, suspended and attached microorganisms mixed in the biological phase, directly adsorbing and degrading part of CODcr; by controlling the activated sludge return ratio, the sludge return ratio (0.5Q), increase the sludge concentration MLSS (mg/l), appropriately increase the sludge age, and improve the efficiency of hydrolyzing insoluble CODcr through the hydrolysis tank in the front stage. In addition, the anaerobic tank is internally circulated through the water pump to increase the upflow rate in the anaerobic tank to achieve anaerobic bacteria sludge The purpose of fully contacting with sewage, thereby improving the effect of anaerobic tank treatment.

The anoxic section adopts anoxic treatment microorganisms as the main part, and the biological phase is a mixture of suspended and attached microorganisms, which belongs to the transition stage from anaerobic to aerobic; the combined filler is suspended in the pool, and the perforated aeration tube is set below to mix the leachate and active The sludge is fully contacted, and the dissolved oxygen rate is controlled at (0.5-1.0mg/L), and the efficiency of nitrification and denitrification is carried out through the sludge reflux in the aerobic tank (reflux ratio 100%), and the NH ₃ -N treatment efficiency is increased.

The aerobic section adopts aerobic treatment of microorganisms as the main part, and the biological phase is mixed with suspended and attached microorganisms; the suspended composite packing can be used for re-cutting the air bubbles during the aeration process, and combined with the microporous aerator, the oxygen absorption rate is improved from ordinary perforated The 2% efficiency of the tube is increased to 8-9%, which improves the power efficiency and increases the efficiency of biochemical treatment.

Anaerobic + anoxic + aerobic microorganisms are strictly classified. Due to the anaerobic, anoxic, and aerobic processes, microorganisms are often in the alternation of internal/external respiration, and the amount of sludge generated is small. While realizing the degradation of organic matter, biological denitrification is realized.

5. Membrane treatment process control

The reverse osmosis device is selected for advanced treatment of the leachate after biological treatment.

Capacity of a single set of reverse osmosis equipment: 150m ³ /d (25°C), a total of one set is installed.

Operating pressure of reverse osmosis: 1.0MPa-1.8MPa.

Water recovery rate of reverse osmosis device: >80%.

The process description of membrane treatment is as follows:

(1) Water inlet tank and booster pump: provide the pressure and flow of the secondary reverse osmosis system.

(2) Mechanical filter: used to intercept mechanical particles and colloids in water.

(3) Reverse osmosis device: It consists of a security filter, a first-stage high-pressure pump, a first-stage reverse osmosis, a second-stage high-pressure pump, a second-stage reverse osmosis, and an alkali dosing device, which can remove more than 99% of inorganic salts and more than 95% of organic matter in water .

The technical process of the present invention is as follows: the leachate from the landfill is collected by the collection system, concentrated in the adjustment tank to adjust the water quality and water quantity; then the pump is lifted into the pH adjustment tank of the primary sedimentation tank, and the Lime adjusts the pH value of the leachate to above 10; the effluent from the pH adjustment tank enters the sedimentation tank in the primary sedimentation tank, during which polymer PAM is added to make the emulsified sediment flocculate and agglomerate through the polymer to form macromolecular precipitation Accelerate the solid-liquid separation of precipitation; the water from the sedimentation tank enters the intermediate pool in the primary sedimentation tank, and the water in the intermediate pool is lifted by the pump into the stripping tower to blow off nitrogen. The contact area is conducive to the removal of ammonia nitrogen; the ammonia nitrogen blown out is absorbed by concentrated sulfuric acid through the absorption tower to form ammonium sulfate for recycling, so as to avoid secondary pollution caused by ammonia being directly discharged into the atmosphere; the water from the blow off tower enters the secondary sedimentation tank through the intermediate pool Add coagulant to the reaction tank, remove some organic matter through isoelectric point flocculation, and increase the ratio of BOD/COD of the leachate; then enter the A ² /O process device, and treat the leachate and active The sludge is fully mixed, and the macromolecular organic matter is decomposed by anaerobic bacteria to convert it into a small molecular organic matter; the combined filler is suspended in the A/O anoxic pool and the aerobic pool, and the underwater activity is activated by aeration and stirring through large pores in the anoxic pool. The sludge and leachate are fully mixed, and some ammonia nitrogen is removed by nitrification and denitrification through the backflow of the leachate in the aerobic pool; the aerobic pool uses a three-leaf Roots blower and a microporous aeration head for aeration, and each pool operates independently , microbial phase separation, high treatment efficiency; the leachate after biological treatment enters the final sedimentation tank to settle sludge, and the effluent of the final sedimentation tank is subjected to sedimentation and oxidation disinfection treatment through the membrane treatment system to ensure that the leachate discharge meets the standard; among them, the primary sedimentation tank, The sludge from the secondary sedimentation tank, the final sedimentation tank and the remaining sludge from membrane treatment enter the sludge tank and are squeezed dry by the filter press before being sent to the landfill for treatment. The leachate that does not meet the discharge standard after membrane treatment is returned to the adjustment tank .

As shown in Figure 1, a system for treating leachate in domestic waste landfills, the system includes a regulating tank, a pre-aeration tank, a primary sedimentation tank, an ammonia stripping tower, an intermediate pool, and a secondary sedimentation tank connected in sequence by pipelines. Pool, A ² /O process unit, final sedimentation tank, temporary storage tank, membrane treatment system and clean water tank. Among them, the primary sedimentation tank, secondary sedimentation tank, final sedimentation tank and reverse osmosis device are connected to the sludge tank through pipelines, the sludge tank is connected with a filter press, and the ammonia stripping tower is connected to the absorption tower.

The primary sedimentation tank includes a PH adjustment tank, a vertical flow sedimentation tank and an intermediate tank.

The A ² /O process device consists of an upflow anaerobic bed and an A/O pool connected in sequence through pipelines, and the A/O pool includes an anoxic pool and an aerobic pool.

The membrane treatment system includes a water inlet tank, a booster pump, a mechanical filter and a reverse osmosis device connected in sequence by pipelines. The reverse osmosis device consists of a security filter, a first-stage high-pressure pump, a first-stage reverse osmosis, a second-stage high-pressure pump, a second-stage reverse osmosis and an alkali dosing device.

Below in conjunction with accompanying drawing, each point of the system of the present invention is introduced, and this refuse treatment plant is 100m ³ /d leachate treatment system:

Pre-exposure pool:

For homogenizing sewage. The capacity of the pool is 125m ³ , the height of the pool body is 3.0m, the size is: 4.0m×6.25m×5.0m, and the above-ground steel concrete structure. The pre-exposure tank is equipped with two lifting pumps, one for use and one for standby. The lifting pump is 25ZW8-15, 1.5Kw type; one input liquid level gauge is KY-2000 type, which automatically controls the operation of the pump.

Primary sedimentation tank PH adjustment tank:

Add lime to adjust the pH of the leachate. The size is: 0.8m×1.6m×1.1m, the tank is divided into reaction tank and coagulation tank, made of stainless steel. There are 2 sets of stirring devices, power 0.55KW; lime dosing device HT-10, 1 set (including hopper volume 10, air compressor 7.5KW, feeding and stirring system 1.67KW, dissolving and mixing system 0.55KW, dosing device Φ1.6 *6.8(m); storage tank Φ1.0*2.5(m)); dosing pump GW15-80, 1 set; PAM dosing uses diaphragm metering pump JWM-80, 0.25KW, 1 set; re-line PH meter 2 set.

Primary sedimentation tank vertical flow sedimentation tank and intermediate tank:

Used for precipitation to remove various heavy metal hydroxides and suspended solids. The surface load is 0.7m ³ /m ² .h, the effective pool capacity is 30.6m ³ , the pool body height is 5.0m, and the size is: 3.0m×3.0m×5.0m; with an intermediate pool of 1.5m×3.0m×5.0m, ground type steel concrete structure. One set of vertical flow tube Φ400; one set of triangular weir plate; one set of slag retaining plate; two lift pumps of 50ZW15-30 with power 3.0KW in the middle pool; and one set of KY-2000 input liquid level gauge.

Ammonia stripping tower:

The pH of the leachate is controlled to be above 10 by adding lye, and the ammonia is removed by blowing air. The stripping tower size is: Φ1.35*9.0m, the load design of the stripping tower is 3.0m ³ /m ² .h, the gas-liquid ratio is 2500, and the tower base size is: 5.0m×3.25m×0.3m. Matching absorption tower size: Φ1.35*6.0m; material PP structure. Set up one centrifugal fan (BF4-72-4.5), power 7.5KW, air volume 10562m ³ ; equipped with frequency conversion control system; two sulfuric acid pumps 40FB-20, one for use and one for standby, power 2.2KW.

Intermediate pool:

It is used to temporarily store the leachate after stripping. The capacity of the pool is 60m ³ , the height of the pool body is 3.0m, and the size is: 3.0m×4.5m×3.5m. It is an underground steel concrete structure. It is equipped with 2 lifting water pumps 25ZW8-15, 1.5Kw, 2 sets, one for use and one for standby; equipped with 1 set of KY-2000 input liquid level gauge, which automatically controls the operation of the water pump.

Secondary settling tank:

Dosing, coagulation and sedimentation to remove organic matter and suspended matter. The surface load is 0.7m ³ /m ² .h, the effective pool volume is 30.6m ³ , the pool body height is 5.0m, and the size is 3.0m×3.0m×5.0m; it is equipped with an intermediate pool of 1.0m×3.0m×5.0m, which is above ground steel concrete structure. Equipped with 2 sets of coagulation mixers; 2 sets of dosing equipment; vertical flow tube Φ400, 1 piece; 1 set of triangular weir plate; -265, 1 set; 0.55KW, 1 set; 1 set of online PH meter.

Upflow anaerobic bed:

Through the anaerobic hydrolysis acid production section, the macromolecular organic matter is converted into small molecular organic matter; in the methanogenic section, part of the organic matter is completely converted into methane and carbon dioxide. Volume load 1.24kgBOD ₅ /m ³ .d, MLSS: 4-6g/L, sludge load 0.31kgBOD ₅ /kgMLSS.d, ascending velocity 0.6m/h, pool capacity 330m ³ , pool height 5.5, Φ6. 5m×5.5m, 2 pieces, super height 0.4m, HRT3d; backflow pump jet flow siphon is used for water intake, and it is a semi-underground steel concrete structure. Equipped with return pump ZW40-20-15, power 2.2KW, 4 sets, two for two purposes and two for standby; combined packing 70m ³ ; two sets of three-phase separators, two sets of water distributors.

A/O pool:

Ammonia nitrogen is removed through nitrification and denitrification, and organic matter is further degraded. BOD ₅ sludge load: 0.13kgBOD ₆ /kgMLVSS.d, SVI＝150, X R＝10 ⁶ /SVI*υ＝6600mg/l, external return ratio 100%; concentration _of mixed liquid sludge in aeration tank X＝3300mg /l; TN removal rate η _N =(143-72)/143=50%, then internal reflux multiple R = η _N /(1-η _N )=1. The effective pool volume is 325m ³ , the pool depth is 4.5m, the pool width is 4.0m, the pool length is 18m, and the residence time is 78h. The output of excess sludge is 8.6Kg/d, the moisture content of sludge is 99.2%, the amount of excess sludge q=1.08m ³ /d, the sludge age is ts=26.54d; the oxygen demand is 241.35kgO ₂ /d; The air supply volume is 5.73m ³ /min. It is a semi-ground steel concrete structure. Equipped with 252m ³ of combined packing, 172 sets of microporous aeration heads; 1 set of internal return pump 25ZW8-15 self-priming pump; 2 sets of three-leaf fan SSR100-H, one for use and one for standby.

Final sinking pool:

Used for sedimentation of aerobic effluent sludge to make the effluent clear and light in mud quality. The surface load of the sedimentation tank is 0.25m ³ /m ² .h, jointly built, the pool capacity is 40m ³ , the size is 4.0m×7.0m×5.0m, and there is a reaction tank and a water distribution tank in front. It is a semi-ground steel concrete structure. Equipped with inclined pipe 17m ³ ; 2 sets of dosing equipment; 1 set of overflow weir; diaphragm metering pump JWM-40, 0.25KW, 1 set; JZM-256, 0.55KW, 1 set; 2 sets of mixers, power 0.55 KW.

Sludge pool:

It is used to store, concentrate and stabilize the remaining sludge from sedimentation and biochemical treatment; the PH value is adjusted by primary lime, the dosing amount is 1%, the sludge production is 0.8%, which is 0.8 tons, and the sludge moisture content is 97%, which is 26.67 m ³ /d; secondary physicochemical dosing amount is 0.2%, sludge production is 0.1%, which is 0.1 tons, and sludge moisture content is 98%, which is 5.0m ³ /d; sludge production in biochemical section: anaerobic section 0.1-0.2kg mud/kgBOD ₅ , total consumption of BOD ₅ 413Kg, mud production 82.6Kg/d, or 10.33m ³ ; mud production in the aerobic section is 8.6Kg/d, sludge moisture content is 99.2%, or 1.08m ³ /d; the daily sludge production is 10.8m ³ ; the total sludge production is 52.8m ³ /d, and the water content is 97-99%. The dry sludge is 1000kg; the size of the sludge tank is 3.0mL×6.5mW×3.5mH. It is an underground steel concrete structure. Equipped with screw pump G40, power 3.0KW, 2 sets; X _M Y80/1000 chamber filter press 2 sets, one for use and one for standby, power 3.0KW; mud pump 1PN, flow rate 16m ³ /d, power 3KW; sludge Reaction tank Φ1.2*1.8; power 1.5KW reaction mixer.

Reverse osmosis device:

Through membrane treatment, organic matter is completely removed. Treat 4.2m ³ /h. It is a complete set of stainless steel bracket and membrane tube structure.

Clean water tank:

Used for temporary storage of sewage. The size is 4.5m×5.5m×3.5m; steel concrete structure. Equipped with submersible sewage pump WQ50-20-7, two sets, power 0.75KW.

Application example 1:

The landfill leachate is treated with the above process, the average value of COD _cr at the water inlet is 9800mg/l, the average value of ammonia nitrogen at the water inlet is 1500mg/l, after treatment, the average value of COD _cr at the water outlet is 85mg/l, and the average value of ammonia nitrogen at the water outlet is 9.0mg/l.

Example 2:

Using the above process to treat landfill leachate, the average COD _cr of the raw liquid at the water inlet is 8000mg/L, and the average ammonia nitrogen of the raw liquid is 1046mg/l. After treatment, the average COD _cr and average ammonia nitrogen at the water outlet are 80mg/l and 8.5mg/l.

Claims (5)

1. A method for treating leachate from domestic waste landfill, characterized in that: the method is composed of ammonia stripping, coagulation sedimentation, biochemical treatment and membrane treatment, and mainly includes the following steps: (1) Carry out ammonia blow-off to leachate, degrade the ammonia nitrogen in the landfill leachate, described ammonia blow-off treatment process adopts air blow-off method; (2) Carry out coagulation and precipitation treatment to the leachate after ammonia stripping, remove the biodegradability of organic matter and suspended matter; (3) carry out biochemical treatment to the sewage treated by coagulation and sedimentation, the described biochemical treatment process adopts A ² /O process, and the described A ² /O process consists of anaerobic microbial treatment section, anoxic microbial treatment section and The composition of the aerobic microbial treatment section; (4) Membrane treatment is performed on the biochemically treated sewage, and the membrane treatment process uses a reverse osmosis process to perform advanced treatment on the biochemically treated leachate. 2. A device for treating leachate from a domestic waste landfill, characterized in that the device includes a regulating tank, a pre-aeration tank, a primary settling tank, an ammonia stripping tower, an intermediate pool, and a secondary settling tank connected in sequence through pipelines. tank, A ² /O process device, final sedimentation tank, temporary storage tank, membrane treatment system and clear water tank, the A ² /O process device is composed of upflow anaerobic bed, A/O tank connected in sequence through pipelines Composition, the A/O pool includes anoxic pool and aerobic pool, wherein, the primary sedimentation tank, secondary sedimentation tank, final sedimentation tank and membrane treatment system are connected to the sludge tank through pipelines, and the sludge tank is connected with a filter press, ammonia The stripping tower is connected with the absorption tower. 3. The device for treating leachate from domestic waste landfills as claimed in claim 2, wherein said primary sedimentation tank comprises a pH adjustment tank, a vertical flow sedimentation tank and an intermediate pool. 4. The device for controlling the leachate of domestic garbage landfill as claimed in claim 2, wherein: said membrane treatment system comprises a water inlet tank, a booster pump, a mechanical filter and a reverse filter which are successively connected by pipelines. Penetration device. 5. The device for treating the leachate of domestic garbage landfill as claimed in claim 4, characterized in that: the reverse osmosis device consists of a security filter, a first-stage high-pressure pump, a first-stage reverse osmosis, and a second-stage high-pressure pump , secondary reverse osmosis and alkali dosing device.

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