Non-membrane combined advanced oxidation leachate treatment system

Abstract

The application discloses a non-membrane combined advanced oxidation landfill leachate treatment system. In the application, a non-membrane landfill leachate treatment process is obtained by optimizing combination of a physical and chemical method and an advanced oxidation method, the treatment efficiency of the leachate is high, the effluent water quality is stable and up to the standard, there is no membrane concentrated liquid disposal problem, the operation cost is reduced, less wearing parts are used, and the later maintenance and management are convenient. The aerobic short-term nitrification and denitrification, Fenton-iron carbon micro-electrolysis and denitrification advanced nitrogen removal process are combined, the iron carbon micro-electrolysis is used in the front section to reduce nitrite nitrogen into nitrogen, the Fenton reagent is added in the iron carbon micro-electrolysis process, nitrite and organic matter are further oxidized, residual nitrite nitrogen is converted into nitrate nitrogen, is removed through the rear section denitrification process, the ozone advanced oxidation reflux liquid can provide the carbon source for the denitrification process, the denitrification efficiency is high, and the biological treatment process can always maintain high efficiency.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of landfill leachate treatment, and particularly relates to a non-membrane combined landfill leachate treatment system of advanced oxidation. BACKGROUND

[0002] At present, the garbage classification means adopted in China is not thorough, and the domestic garbage generally has problems of high water content and large proportion of organic garbage. Garbage leachate is generated in the process of garbage treatment, disposal and stacking. About 5.0*10 7 t of garbage leachate is generated in China every year. The garbage leachate has complex components, and main pollution components include COD, BOD, SS, nitrogen, phosphorus, heavy metals and complex high-molecular organic matters, etc. The pollution sources are organic matters, plastics, waste paper, metals and textiles in the garbage. The garbage leachate of landfill sites in different regions of China has great differences in water quality. The leachate has characteristics of pungent odor, high colority, poor biodegradability, many types of pollutants, high concentrations of COD and ammonia nitrogen, etc. And the concentrations of various pollutants change with the increase of landfill time. The garbage leachate is harmful, and it is particularly important to treat the leachate to reach the standard. Organic substances in the leachate produce odor substances such as ammonia and hydrogen sulfide under the action of microorganisms, polluting the air environment. If the leachate is discharged into water bodies without proper treatment, it may cause serious water pollution problems. The carcinogenic substances such as heavy metals in the leachate may cause harm to human health through enrichment. And the salt and acidic substances in the leachate can destroy the soil structure and cause soil salinization. Therefore, it is very important to study the garbage leachate technology with strong pertinence, strong practicability, wide application range, high reliability and high efficiency according to local conditions.

[0003] At present, the garbage leachate in China is mainly treated by pretreatment + membrane treatment process. However, the existing garbage leachate treatment system and method has the following disadvantages: the pretreatment + deep membrane treatment process produces membrane concentrate, and faces problems of regular replacement of membrane components, frequent membrane washing, high operation and maintenance cost, etc. The membrane treatment process essentially filters and retains the pollutants in the leachate, and does not degrade the pollutants. Most of the pollutants are retained in the membrane concentrate, which needs to be disposed again. The disposal of the membrane concentrate is difficult, and improper disposal may cause secondary pollution problems. The pretreatment + biological treatment + membrane deep treatment is the current mainstream technology. However, with the passage of time, the biodegradability of the garbage leachate gradually becomes poor, the biological treatment efficiency becomes low, the pollutant concentration of the biological treatment effluent increases, and the subsequent membrane treatment pressure increases, which will cause problems of membrane blockage, reduced water yield and water quality fluctuation, etc. SUMMARY

[0004] The purpose of the application is to solve the above-mentioned problems, and provide a non-membrane combined landfill leachate treatment system of advanced oxidation.

[0005] The technical solution adopted in this invention is as follows: a non-membrane combined advanced oxidation landfill leachate treatment system, the non-membrane combined advanced oxidation landfill leachate treatment system comprising: a coagulation sedimentation pretreatment tank, an anaerobic hydrolysis acidification tank, an aerobic short-cut nitrification-denitrification tank, a Fenton-iron-carbon micro-electrolysis tank, a deep denitrification tank, an ozone advanced oxidation tank, and a high-efficiency sedimentation tank;

[0006] The aerobic short-cut nitrification-denitrification tank mainly includes: MBBR packing material 1, aeration device 1, inclined plate, built-in effluent pipe, sludge discharge pipe, water temperature controller, built-in self-circulation pipeline, dissolved oxygen monitor 1, and dissolved oxygen monitor 2.

[0007] The Fenton-iron-carbon micro-electrolysis cell includes: Fenton reagent dosing port, baffle plate, iron-carbon packing, aeration device 2, water inlet device, and water pump;

[0008] The deep denitrification tank includes: MBBR packing material II, aeration device III, mixed liquor return pump, and baffles;

[0009] In a preferred embodiment, the coagulation sedimentation pretreatment tank 1 reduces pollutants such as SS, COD and TP in the leachate by adding coagulants and flocculants, thereby reducing the color of the leachate.

[0010] In a preferred embodiment, the supernatant after coagulation and sedimentation treatment flows by gravity to an anaerobic hydrolysis acidification tank. Since the pH adaptation range for hydrolytic fermentation bacteria and acid-producing bacteria is 5.0–6.5, sodium bicarbonate is added to adjust the pH of the leachate to between 5.5 and 6.5 for hydrolysis acidification. The hydraulic retention time is controlled to be 3–5 days. The main function of anaerobic hydrolysis acidification is to convert Kjeldahl nitrogen into ammonia nitrogen. Anaerobic hydrolysis acidification can convert more than 80% of Kjeldahl nitrogen into ammonia nitrogen, and the COD removal rate exceeds 15%.

[0011] In a preferred embodiment, the effluent from the hydrolysis acidification tank flows by gravity into the outer ring of the aerobic short-cut nitrification-denitrification tank. The aerobic short-cut nitrification-denitrification tank has a ring structure design, with an internal self-circulating pipe and a gravity outlet at the bottom of the inner ring wall, which can form an internal self-circulating reflux liquid without additional power equipment. An aeration device is provided on the outer ring.

[0012] In a preferred embodiment, the second dissolved oxygen monitor can detect the DO concentration of the outer ring mixture online in real time and control the DO concentration of the outer ring to be 2~4 mg / L; the first dissolved oxygen monitor can detect the DO concentration of the inner ring mixture online in real time.

[0013] In a preferred embodiment, the MBBR packing material is used for microbial attachment and growth, and the incoming water temperature can be adjusted between 26 and 32°C via a water temperature controller.

[0014] In a preferred embodiment, the outer ring sewage self-circulates into the inner ring, the upper part of the inner ring is provided with an inclined plate, which helps the sludge to sink, and the settled sludge is discharged periodically through a sludge discharge pipe. The supernatant enters the built-in water outlet pipe and is pumped into the Fenton-iron carbon micro-electrolysis cell by a water pump. The Fenton-iron carbon micro-electrolysis cell is provided with two uniform water distribution devices and aeration devices at the bottom and is filled with iron-carbon filler.

[0015] In a preferred embodiment, the sewage flows into the deep denitrification tank, the deep denitrification tank mainly operates in an anaerobic-anoxic-aerobic mode, and the deep denitrification tank is provided with MBBR filler two for microbial attachment and growth, aeration device three, mixed liquid reflux pump and baffle.

[0016] In a preferred embodiment, the deep denitrification tank can remove nitrate in the incoming water and nitrate in the internal reflux mixed liquid by denitrification. The refluxed oxidation liquid provides a carbon source for the denitrification process, and the sludge external reflux ensures the biomass concentration in the system, ensuring that the microorganisms can efficiently treat the leachate. The deep denitrification tank is a pool in which the phosphorus-releasing polyphosphorus bacteria in the anaerobic section and the phosphorus-absorbing polyphosphorus bacteria in the aerobic section can remove part of the TP in the leachate, playing a role in biological phosphorus removal.

[0017] In a preferred embodiment, the effluent of the deep denitrification tank flows into the ozone advanced oxidation tank. The ozone has a high oxidation-reduction potential of 2.07V in water, second only to fluorine, ranking second. It is commonly used for disinfection, deodorization and removal of refractory organic matter and color in water. Ozone advanced oxidation can oxidize and decompose refractory organic matter in the leachate, reduce color, sterilize and disinfect, and has a fast reaction speed. An ozone concentration of 300~1000mg / L is used. After ozone advanced oxidation, the refractory organic matter in the leachate is further decomposed and oxidized, and the oxidation liquid refluxed to the deep denitrification tank is used as a denitrification carbon source. The degradation of organic matter improves the denitrification capacity of the system.

[0018] In summary, due to the adoption of the above technical solutions, the present application has the following advantages:

[0019] 1. In the present application, the front-end pretreatment unit is coagulation sedimentation + anaerobic hydrolysis acidification. Coagulants and flocculants are added in the coagulation sedimentation zone to remove SS, TP and organic pollutants in the leachate, etc., and to improve the transparency of the wastewater. The treatment of the leachate by anaerobic hydrolysis acidification is controlled in the anaerobic hydrolysis acidification stage, mainly converting Kjeldahl nitrogen into ammonia nitrogen. Hydrolysis acidification can convert part of the non-dissolved organic matter and refractory organic matter in the leachate into dissolved organic matter and easily biodegradable small molecular organic matter, improving the biodegradability of the leachate.

[0020] 2、In the application, the deep treatment unit comprises: aerobic short-cut nitrification and denitrification, Fenton-iron-carbon micro-electrolysis, deep denitrification, ozone advanced oxidation and high-efficiency sedimentation tank. The aerobic short-cut nitrification and denitrification reaction controls the nitrification process of ammonia nitrogen at nitrite nitrogen, the nitrite nitrogen is reduced to nitrogen by the iron-carbon micro-electrolysis reaction, and part of the organic matter is also decomposed. The Fenton reagent is added to the iron-carbon micro-electrolysis reaction zone, which can further oxidize the nitrite and the organic matter, convert the residual nitrite nitrogen into nitrate nitrogen, and improve the biodegradability of the leachate and reduce the toxicity of the leachate.

[0021] 3、In the application, the deep denitrification unit carries out the denitrification reaction, the residual nitrate nitrogen in the iron-carbon micro-electrolysis unit and the nitrate nitrogen in the reflux mixed liquid are removed by denitrification, and the oxidation liquid refluxed by the ozone advanced oxidation can provide a carbon source for the denitrification process. Because the ozone advanced oxidation oxidizes and decomposes the refractory organic matter in the leachate to form biodegradable small-molecule organic matter, the reflux liquid can act as a carbon source in the denitrification process. Finally, the high-efficiency sedimentation unit further improves the water quality, so that the drainage water quality is stable and meets the standard. The non-membrane combined advanced oxidation landfill leachate treatment system is stable in operation, does not produce membrane concentrated liquid, has low treatment cost and is convenient to operate and manage.

[0022] 4、In the application, a non-membrane landfill leachate treatment process is obtained by optimizing the combination of physical and chemical methods and advanced oxidation methods, the leachate treatment efficiency is high, the effluent water quality is stable and meets the standard, there is no membrane concentrated liquid disposal problem, the operation cost is reduced, fewer spare parts are used, and the late maintenance and management are convenient. The anaerobic hydrolysis, Fenton-iron-carbon micro-electrolysis and ozone advanced oxidation processes are adopted, the non-dissolved organic matter and the refractory organic matter in the leachate can be converted into dissolved organic matter and easily biodegradable organic matter, the biodegradability of the leachate is greatly improved, and the biological treatment process always maintains high efficiency. The aerobic short-cut nitrification and denitrification, Fenton-iron-carbon micro-electrolysis and denitrification deep denitrification processes are combined, the nitrite nitrogen is reduced to nitrogen by the iron-carbon micro-electrolysis in the front section, the Fenton reagent is added to the iron-carbon micro-electrolysis process to further oxidize the nitrite and the organic matter, the residual nitrite nitrogen is converted into nitrate nitrogen, and the nitrate nitrogen is removed by the denitrification process in the rear section, the reflux liquid of the ozone advanced oxidation can provide a carbon source for the denitrification process, and the denitrification efficiency is high. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is the process diagram of the non-membrane combined advanced oxidation landfill leachate treatment system of the application;

[0024] Figure 2 is the structure schematic diagram of the aerobic short-cut nitrification and denitrification tank of the application;

[0025] Figure 3is the Fenton-iron carbon micro-electrolysis cell structure schematic diagram of the present application;

[0026] Figure 4 is the deep denitrification pool structure schematic diagram of the present application;

[0027] Figure 5 is the pollutant removal effect diagram of each process section of the system.

[0028] Marked in the figure: 1-coagulation sedimentation pretreatment pool, 2-anaerobic hydrolysis acidification pool, 3-aerobic short-cut nitrification and denitrification pool, 4-Fenton-iron carbon micro-electrolysis cell, 5-deep denitrification pool, 6-ozone advanced oxidation pool, 7-high-efficiency sedimentation pool, 31-MBBR filler one, 32-aeration device one, 33-inclined plate, 34-embedded water outlet pipe, 35-sludge discharge pipe, 36-water temperature controller, 37-embedded self-circulation pipeline, 38-dissolved oxygen monitor one, 39-dissolved oxygen monitor two, 41-Fenton reagent adding port, 42-baffle, 43-iron-carbon filler, 44-aeration device two, 45-water inlet device, 46-water pump, 51-MBBR filler two, 52-aeration device three, 53-mixed liquid reflux pump, 54-baffle. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0030] Reference Figures 1-5 ,

[0031] Example:

[0032] A non-membrane combined advanced oxidation landfill leachate treatment system, comprising: a coagulation sedimentation pretreatment pool 1, an anaerobic hydrolysis acidification pool 2, an aerobic short-cut nitrification and denitrification pool 3, a Fenton-iron carbon micro-electrolysis cell 4, a deep denitrification pool 5, an ozone advanced oxidation pool 6, and a high-efficiency sedimentation pool 7. The aerobic short-cut nitrification and denitrification pool 3 mainly comprises: MBBR filler one 31, aeration device one 32, inclined plate 33, embedded water outlet pipe 34, sludge discharge pipe 35, water temperature controller 36, embedded self-circulation pipeline 37, 38 dissolved oxygen monitor 1, and 39 dissolved oxygen monitor 2. The Fenton-iron carbon micro-electrolysis cell 4 comprises: Fenton reagent adding port 41, baffle 42, iron-carbon filler 43, aeration device two 44, water inlet device 45, and water pump 46. The deep denitrification pool 5 comprises: MBBR filler two 51, aeration device three 52, mixed liquid reflux pump 53, and baffle 54.

[0033] A non-membrane combined advanced oxidation landfill leachate treatment system process diagram, see Figure 1 . The aerobic short-cut nitrification and denitrification pool schematic diagram, seeFigure 2 Fenton-iron-carbon micro-electrolysis cell schematic diagram, see Figure 3 Deep denitrification pool schematic diagram, see Figure 4 .

[0034] The application discloses a non-membrane combined advanced oxidation landfill leachate treatment system.

[0035] The application adds a proper amount of flocculating agent, which can further improve the instability of the floc, make small flocs coagulate into large flocs, improve the settling capacity of the floc, and make the floc more easily separated from water. 3+ The application adds aluminum salt or iron salt coagulant, and the optimal addition amount of the coagulant ranges from 100 mg / L to 300 mg / L equivalent Fe 3+ / Al 3+ The optimal addition ratio of the coagulant to the flocculating agent is 3:1 to 4:1. The coagulation and sedimentation pretreatment has an organic matter removal rate of more than 50%, a TP removal rate of more than 70%, and reduces the colority of the leachate.

[0036] The supernatant after the coagulation and sedimentation treatment flows to the anaerobic hydrolysis acidification tank 2 by itself. The hydrolysis and acidification tank is used for hydrolysis and acidification of the leachate by adding sodium bicarbonate to adjust the pH of the leachate to 5.5 to 6.5, and controlling the hydraulic retention time (HRT) to be 3 to 5 days. The anaerobic hydrolysis acidification mainly converts Kjeldahl nitrogen into ammonia nitrogen. The anaerobic hydrolysis acidification can convert more than 80% of the Kjeldahl nitrogen into ammonia nitrogen, and the COD removal rate is more than 15%.

[0037] The effluent of the hydrolysis acidification tank flows into the outer ring of the aerobic short-cut nitrification and denitrification tank 3 by itself. The aerobic short-cut nitrification and denitrification tank 3 has a ring structure design, is provided with an internal self-circulation pipeline 37 and a self-flowing port at the bottom of the inner ring wall, can form internal self-circulation reflux liquid, has no additional power equipment, and is provided with an aeration device one 32 at the outer ring. The aeration device one 32 can adjust the dissolved oxygen (DO) concentration of the solution at any time. The DO concentration of the mixed liquid in the outer ring can be detected on line and in real time through a 39 dissolved oxygen monitor 2, and the DO concentration in the outer ring is controlled to be 2 to 4 mg / L. The DO concentration of the mixed liquid in the inner ring can be detected on line and in real time through a 38 dissolved oxygen monitor 1, and the DO concentration in the inner ring is controlled to be 0.1 to 0.4 mg / L. The anaerobic-anoxic-aerobic state of the inner and outer rings is realized, the inner ring can also perform denitrification reaction while the outer ring is aerated, and synchronous nitrification and denitrification is performed, so that the denitrification performance is greatly improved.

[0038] The outer ring adds MBBR filler 31 for microorganism to attach and grow, and the water temperature can be adjusted to 26-32℃ by the water temperature controller 36. In combination with adjustment of sludge retention time and HRT, the ammonia nitrogen in the leachate can be converted into nitrite nitrogen by aerobic short-cut nitrification, the ammonia nitrogen removal rate is over 90%, and the organic matter removal rate can reach 30%. The sewage in the outer ring is self-circulated into the inner ring, the inner ring is provided with a tilted plate 33 which is helpful for sludge sinking, and the settled sludge is discharged periodically through a sludge discharge pipe 35.

[0039] The supernatant enters the built-in outlet pipe and is pumped into the Fenton-iron carbon micro-electrolysis cell 4 by the water pump 46. The Fenton-iron carbon micro-electrolysis cell 4 is provided with a uniform water distribution device 45 and an aeration device 44 at the bottom, is filled with iron-carbon filler 43, is periodically back-flushed by aeration, and adopts the water pump upward water inlet mode, so that the iron-carbon filler layer will not be blocked.

[0040] The ammonia nitrogen is converted into nitrite nitrogen by aerobic short-cut nitrification, the nitrite nitrogen is directly reduced into nitrogen by using the iron-carbon micro-electrolysis reaction instead of the traditional anaerobic denitrification process for treating the leachate, the TN removal rate can reach over 70%, the mass ratio of Fe / C is controlled to be between 1.1:1 and 1.3:1, the reaction time is between 45 and 55 min, 0.04-0.08 mol / L of Fenton reagent is added through the Fenton reagent adding port 41, the mass ratio of H2O2 to Fe 2+ is 4:1, and the added H2O2 is catalyzed by Fe 2+ to form ·OH which has stronger oxidation and can oxidize and remove most of the organic matters in the leachate, the removal rate of COD can reach over 80%, the baffle plate 42 can prevent short flow of the Fenton reagent, the Fenton reagent degrades part of the refractory organic matters, further improves the biodegradability of the leachate, and oxidizes the residual nitrite nitrogen into nitrate nitrogen.

[0041] The sewage is self-flowed into the deep denitrification tank 5, the deep denitrification tank 5 mainly operates in the anaerobic-anoxic-aerobic mode, is provided with MBBR filler 2 51 for microorganism to attach and grow, aeration device 3 52, mixed liquid backflow pump 53 and baffle 54, the mixed liquid internal backflow ratio is 50%-100%, the sludge external backflow ratio is 30%-80%, and the oxidation liquid backflow ratio is 60%-120%. The deep denitrification tank 5 can remove the nitrate nitrogen in the incoming water and the nitrate nitrogen in the internal backflow mixed liquid by denitrification, the backflow oxidation liquid provides carbon source for the denitrification process, the sludge external backflow ensures the biomass concentration in the system, and ensures that the microorganism can efficiently treat the leachate.

[0042] The depth denitrification tank 5 is the phosphorus release of the polyphosphorus bacteria in the anaerobic section and the phosphorus absorption of the polyphosphorus bacteria in the aerobic section in the tank, can remove part of the TP in the leachate, and plays a role of biological phosphorus removal. The effluent of the depth denitrification tank 5 flows into the ozone advanced oxidation tank 6 by itself, because the ozone has a high oxidation-reduction potential 2.07V in water, only next to fluorine, ranks the second, is often used for disinfection, deodorization and removal of refractory organic matter and colority in water, the ozone advanced oxidation can oxidize and decompose the refractory organic matter in the leachate, reduce the colority, sterilize and disinfect, the reaction speed is fast, the ozone concentration is 300-1000mg / L, after the ozone advanced oxidation, the refractory organic matter in the leachate is further decomposed and oxidized, and the oxidized liquid of the depth denitrification tank is used as a denitrification carbon source, degrades the organic matter and improves the denitrification capacity of the system.

[0043] The effluent of the ozone advanced oxidation tank flows into the high-efficiency sedimentation tank 7 by itself, coagulant and flocculant are added, the coagulant forms a colloid with the pollutants in water, the flocculant has an electric neutralization effect on the colloid, the hydrolysis product has a bridging adsorption effect, has a selective adsorption effect on the dissolved substances, makes the colloid and fine suspended solids in the leachate coagulate into flocculation bodies, and the flocculation bodies are removed by sedimentation. The coagulant and flocculant can remove the COD, total phosphorus and other pollutants in the leachate, improve the colority, further improve the water quality of the sewage, the mixing time is 5-10min, the flocculation time is 15-25min, the surface load of the high-efficiency sedimentation tank is 10-15m 3 ·m -2 ·h -1 , and the effluent of the high-efficiency sedimentation tank can stably reach the standard of “Standard for Pollution Control on Solid Waste Landfill Sites” (GB 16889-2008).

[0044] The test uses the leachate generated by a landfill, and the initial concentration is: the COD concentration is about 4500mg / L, the total nitrogen concentration is about 1900mg / L, the ammonia nitrogen concentration is about 1200mg / L, and the TP concentration is about 35mg / L. After treatment, the actual effluent COD is <22mg / L, the total nitrogen is <31mg / L, the ammonia nitrogen is <10mg / L, and the TP is <0.15mg / L, and the continuous and stable operation can be realized, the drainage stably reaches the standard of Table 2 of GB 16889-2008, the operation and management are convenient, no concentrated liquid is generated, and the treatment and disposal cost is low. The pollutant removal effect diagram of each process section is shown in Figure 5 .

[0045] From the above experimental data, it can be known that:

[0046] In the application, the front-end pretreatment unit is coagulation sedimentation + anaerobic hydrolysis acidification, coagulation and flocculation are added in the coagulation sedimentation zone, mainly to remove SS, TP and organic pollutants in the leachate, and to improve the transparency of the wastewater; the anaerobic hydrolysis acidification is controlled in the anaerobic hydrolysis acidification stage, mainly to convert Kjeldahl nitrogen into ammonia nitrogen, and a part of non-dissolved organic matter and difficult biodegradable organic matter in the leachate is converted into dissolved organic matter and easily biodegradable small-molecule organic matter, improving the biodegradability of the leachate.

[0047] In the application, the advanced treatment unit includes: aerobic short-cut nitrification and denitrification, Fenton-iron-carbon micro-electrolysis, deep denitrification, ozone advanced oxidation and high-efficiency sedimentation tank. The aerobic short-cut nitrification and denitrification reaction controls the nitrification process of ammonia nitrogen in nitrite nitrogen, and the nitrite nitrogen is reduced to nitrogen by the iron-carbon micro-electrolysis reaction, and part of the organic matter is also decomposed. The Fenton reagent is added in the iron-carbon micro-electrolysis reaction zone, which can further oxidize the nitrite and the organic matter, convert the residual nitrite nitrogen into nitrate nitrogen, and the Fenton reagent decomposes the difficult biodegradable organic matter, improves the biodegradability of the leachate, and reduces the toxicity of the leachate.

[0048] In the application, the deep denitrification unit performs denitrification reaction, removes the nitrate nitrogen remaining in the iron-carbon micro-electrolysis unit and the nitrate nitrogen in the reflux mixed liquid, and the oxidation liquid refluxed by the ozone advanced oxidation can provide carbon source for the denitrification process. Because the ozone advanced oxidation oxidizes and decomposes the difficult-to-degrade organic matter in the leachate to form biodegradable small-molecule organic matter, the reflux liquid can act as a carbon source in the denitrification process. Finally, through the high-efficiency sedimentation unit, the water quality is further improved, so that the drainage water quality is stable and meets the standard. The non-membrane combined advanced oxidation landfill leachate treatment system is stable in operation, no membrane concentrate liquid is produced, the treatment cost is low, and the operation and management are convenient.

[0049] The present application is a non-membrane landfill leachate treatment process, which is obtained by combining physical and chemical method with advanced oxidation method, has high leachate treatment efficiency, stable effluent quality, no membrane concentrate liquid disposal problem, reduces operation cost, uses less wear parts and is convenient for later maintenance and management.

[0050] It should be noted that, in this document, relational terms such as first and second and the like can be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "comprises... a" does not, without more constraints, exclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.

[0051] The above examples are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions recorded in the foregoing examples can be modified, or some technical features can be replaced by equivalent ones; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A non-membrane combined advanced oxidation landfill leachate treatment system, characterized in that: The non-membrane combined advanced oxidation landfill leachate treatment system includes a coagulation sedimentation pretreatment tank (1), an anaerobic hydrolysis acidification tank (2), an aerobic short-cut nitrification-denitrification tank (3), a Fenton-iron-carbon micro-electrolysis tank (4), a deep denitrification tank (5), an ozone advanced oxidation tank (6), and a high-efficiency sedimentation tank (7), arranged in sequence. The aerobic short-cut nitrification-denitrification tank (3) mainly includes: MBBR packing material 1 (31), aeration device 1 (32), inclined plate (33), built-in effluent pipe (34), sludge discharge pipe (35), water temperature controller (36), built-in self-circulation pipeline (37), dissolved oxygen monitor 1 (38), and dissolved oxygen monitor 2 (39). The Fenton-iron-carbon microelectrolysis cell (4) includes: Fenton reagent dosing port (41), baffle plate (42), iron-carbon packing (43), aeration device II (44), water inlet device (45), and water pump (46). After coagulation and sedimentation pretreatment, the supernatant flows by gravity to the anaerobic hydrolysis acidification tank (2). Since the pH adaptation range of hydrolytic fermentation bacteria and acid-producing bacteria is 5.0~6.5, sodium bicarbonate is added to adjust the pH of the landfill leachate to between 5.5 and 6.5 for hydrolysis acidification. The hydraulic retention time is controlled to be 3~5 days. The main function of anaerobic hydrolysis acidification is to convert Kjeldahl nitrogen into ammonia nitrogen. Anaerobic hydrolysis acidification converts more than 80% of Kjeldahl nitrogen into ammonia nitrogen, and the COD removal rate exceeds 15%. The effluent from the anaerobic hydrolysis acidification tank flows by gravity into the outer ring of the aerobic short-cut nitrification and denitrification tank (3). The aerobic short-cut nitrification and denitrification tank (3) is designed with a ring structure, with an internal self-circulating pipe (37) and a gravity outlet at the bottom of the inner ring wall to form an internal self-circulating reflux liquid. There is no additional power equipment. An aeration device (32) is provided on the outer ring. The dissolved oxygen monitor 2 detects the DO concentration of the outer ring mixture online in real time and controls the DO concentration of the outer ring to be 2~4 mg / L; the dissolved oxygen monitor 1 (38) detects the DO concentration of the inner ring mixture online in real time. The MBBR packing material (31) is used for microbial attachment and growth, and the incoming water temperature is adjusted to between 26 and 32°C by the water temperature controller (36). The outer ring sewage is self-circulated into the inner ring. The upper part of the inner ring is provided with an inclined plate (33) to help the sludge settle. The settled sludge is periodically discharged through the sludge discharge pipe (35). The supernatant enters the built-in water outlet pipe and is pumped into the Fenton-iron-carbon micro-electrolysis cell (4) by the water pump (46). The bottom of the Fenton-iron-carbon micro-electrolysis cell (4) is provided with a uniform water distribution device (45) and an aeration device II (44), and the inside is filled with iron-carbon packing material (43).

2. The non-membrane combined advanced oxidation landfill leachate treatment system as described in claim 1, characterized in that: The wastewater flows by gravity into the deep denitrification tank (5). The deep denitrification tank (5) mainly operates in an anaerobic-anoxic-aerobic mode. The deep denitrification tank (5) is equipped with MBBR packing material II (51) for microbial attachment and growth, aeration device III (52), mixed liquor return pump (53), and baffle (54).

3. The non-membrane combined advanced oxidation landfill leachate treatment system as described in claim 1, characterized in that: The deep denitrification tank (5) removes nitrate nitrogen from the incoming water and nitrate nitrogen from the internal reflux mixed liquor through denitrification. The refluxed oxidizing liquid provides a carbon source for the denitrification process. The external sludge reflux ensures the biomass concentration in the system and ensures efficient microbial treatment of landfill leachate. The deep denitrification tank (5) is where polyphosphate-accumulating bacteria in the anaerobic section release phosphorus and polyphosphate-accumulating bacteria in the aerobic section absorb phosphorus, removing some TP from the landfill leachate and playing a role in biological phosphorus removal.

4. The non-membrane combined advanced oxidation landfill leachate treatment system as described in claim 1, characterized in that: The effluent from the deep denitrification tank (5) flows by gravity into the ozone advanced oxidation tank (6). Ozone has a high oxidation-reduction potential of 2.07V in water, second only to fluorine. It is often used for disinfection, deodorization, and removal of refractory organic matter and color from water. Ozone advanced oxidation oxidizes and decomposes the refractory organic matter in landfill leachate, reduces color, sterilizes and disinfects. The reaction speed is fast. The ozone concentration is between 300 and 1000 mg / L. After ozone advanced oxidation, the refractory organic matter in landfill leachate is further decomposed and oxidized. The oxidized liquid returned to the deep denitrification tank is used as a carbon source for denitrification, which degrades organic matter and improves the denitrification capacity of the system.

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