CN112759200B - Treatment method for achieving full quantity of landfill leachate to standard - Google Patents

Treatment method for achieving full quantity of landfill leachate to standard Download PDF

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CN112759200B
CN112759200B CN202110041066.5A CN202110041066A CN112759200B CN 112759200 B CN112759200 B CN 112759200B CN 202110041066 A CN202110041066 A CN 202110041066A CN 112759200 B CN112759200 B CN 112759200B
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anaerobic
denitrification
nitrogen
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bacteria
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CN112759200A (en
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王晓君
陈少华
冯华良
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Institute of Urban Environment of CAS
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    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F9/00—Multistage treatment of water, waste water or sewage
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/001—Processes for the treatment of water whereby the filtration technique is of importance
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
    • C02F1/467—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis by electrochemical disinfection; by electrooxydation or by electroreduction
    • C02F1/4672—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis by electrochemical disinfection; by electrooxydation or by electroreduction by electrooxydation
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/06—Contaminated groundwater or leachate
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00—Biological treatment of water, waste water, or sewage
    • C02F3/28—Anaerobic digestion processes
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00—Biological treatment of water, waste water, or sewage
    • C02F3/28—Anaerobic digestion processes
    • C02F3/2853—Anaerobic digestion processes using anaerobic membrane bioreactors
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00—Biological treatment of water, waste water, or sewage
    • C02F3/30—Aerobic and anaerobic processes
    • C02F3/301—Aerobic and anaerobic treatment in the same reactor
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00—Biological treatment of water, waste water, or sewage
    • C02F3/30—Aerobic and anaerobic processes
    • C02F3/302—Nitrification and denitrification treatment
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00—Biological treatment of water, waste water, or sewage
    • C02F3/30—Aerobic and anaerobic processes
    • C02F3/302—Nitrification and denitrification treatment
    • C02F3/307—Nitrification and denitrification treatment characterised by direct conversion of nitrite to molecular nitrogen, e.g. by using the Anammox process

Abstract

The invention relates to a treatment method for achieving the full quantity of landfill leachate, which comprises the following steps: s100: the garbage leachate is homogenized by a regulating tank and then enters a denitrification reactor, and short-cut nitrification, denitrification, short-cut denitrification and anaerobic ammonia oxidation are performed in the denitrification reactor to realize the synergic denitrification; s200: after being treated by the denitrification reactor, the effluent enters a filtering unit for mud-water separation, so that the concentration of suspended matters in the effluent is reduced; s300: filtered water enters an electrochemical advanced oxidation reactor, and refractory organic matters are converted into degradable organic matters by utilizing direct oxidation and indirect oxidation ways, so that the biodegradability of the leachate is improved; s400: and (4) feeding the electrolyzed effluent into a secondary biochemical tank, and performing denitrification reaction by using the degradable organic matters obtained by conversion in the step S300 to further reduce COD and TN in the water so as to ensure that the electrolyzed effluent meets the discharge standard.

Description

Treatment method for achieving full quantity of landfill leachate to standard
Technical Field
The invention belongs to the technical field of landfill leachate treatment, and particularly relates to a treatment method for achieving the full quantity of landfill leachate.
Background
With the development of the urbanization process, the annual output of fresh percolate of urban domestic garbage in China reaches 2900 ten thousand tons. Landfill leachate is a kind of wastewater with high ammonia nitrogen and difficult degradation, and ammonia Nitrogen (NH) of the wastewater 4 + The concentration of-N) generally fluctuates in the range of 1000-3000 mg/L, which is about 100 times of that of general urban domestic sewage. High concentration of NH 4 + The toxicity of N to microorganisms is a difficult point in biochemical treatment. In addition, the concentration of organic matters (measured by chemical oxygen demand COD) in the leachate can reach 1000-60000 mg/L, and the biodegradability presents obvious space-time difference.
The construction of the regulations for landfill leachate treatment in China is gradually perfected, wherein the landfill pollution control Standard (GB 16889-2008) stipulates that complete treatment systems need to be constructed in various constructed or put into use landfill sites to treat landfill leachate generated in reservoir areas, and COD, total nitrogen and ammonia nitrogen can reach the standard and can be discharged when the COD, the total nitrogen and the ammonia nitrogen respectively reach 100mg/L, 40mg/L and 25 mg/L. However, the condition that the landfill leachate treatment in each province and city does not reach the standard is more prominent, and especially the two indexes of COD and the concentration of nitrogen-containing substances reach the standard difficultly.
At present, the mainstream landfill leachate treatment process is an anoxic/aerobic (a/O) -Membrane Bioreactor (MBR) -Nanofiltration (NF) -Reverse Osmosis (RO) process, which is called a full-membrane process for short. The traditional A/O process needs to add carbon sources such as methanol, glucose and the like into the anoxic pond to promote denitrification, but the running cost is higher. Meanwhile, in order to reach the discharge standard that the COD of the effluent is less than 100mg/L, nanofiltration and reverse osmosis filtration are generally required to be added. As nanofiltration and reverse osmosis only play a role in physical filtration, 20-40% of concentrated solution in volume can be produced while the permeate reaches the standard. The concentration of refractory organic matters in the concentrated solution is very high, and the concentrated solution contains high-concentration salt, so that the treatment difficulty is higher, the cost is higher, and the method is one of the most troublesome problems encountered in the full-film process. In addition, the full-membrane process also has the problems of serious membrane pollution, short membrane life, long aeration time of MBR biochemical process, large additional carbon source requirement and the like, so the treatment cost is high and the financial burden is large. Therefore, development of alternative landfill leachate treatment processes capable of realizing long-term stable standard operation is urgently needed.
Disclosure of Invention
Aiming at the problems, the invention provides a treatment method for treating the garbage leachate with the full amount reaching the standard, the treatment method is used for treating wastewater with high ammonia nitrogen and refractory organic matters, such as the garbage leachate, on the basis of the traditional sewage treatment process, by adopting more efficient and environment-friendly anaerobic ammonia oxidation and electrochemical advanced oxidation technologies which are matched with each other, removing nitrogen-containing substances and refractory organic matters in the garbage leachate by utilizing the synergistic action of multifunctional bacteria in a denitrification reactor; the electrochemical advanced oxidation reactor is used for removing refractory organic matters, the biodegradability is improved, and the traditional technologies such as filtration, biochemistry and the like are matched, so that the total quantity of the landfill leachate reaches the standard, the landfill leachate can stably run for a long time and continuously, the treatment time is greatly shortened, and the treatment cost is reduced.
The treatment method for achieving the full quantity of the landfill leachate comprises the following steps:
s100: the landfill leachate is homogenized by a regulating tank and then enters a denitrification reactor, and shortcut nitrification, denitrification, shortcut denitrification and anaerobic ammonia oxidation are carried out in the denitrification reactor to realize synergic denitrification;
s200: after being treated by the denitrification reactor, the effluent enters a filtering unit for mud-water separation, so that the concentration of suspended matters in the effluent is reduced;
s300: filtered water enters an electrochemical advanced oxidation reactor, and nondegradable organic matters are converted into degradable organic matters by utilizing direct oxidation and indirect oxidation ways, so that the biodegradability of the leachate is improved;
s400: and (4) feeding the electrolyzed effluent into a secondary biochemical tank, and performing denitrification reaction by using the degradable organic matters obtained by conversion in the step S300 to further reduce COD and TN in the water so as to ensure that the electrolyzed effluent meets the discharge standard.
The treatment method utilizes the denitrification reactor to treat the high-ammonia nitrogen leachate, takes anaerobic ammonium oxidation bacteria as a main part in the denitrification reactor, takes shortcut nitrification, denitrification and shortcut denitrification bacteria as auxiliary parts, and performs synergistic treatment to reduce the concentration of nitrogen. On the other hand, after the leachate is subjected to electrochemical advanced oxidation treatment, organic matters which are difficult to degrade are removed and converted into degradable organic matters, and the biodegradability of the leachate is obviously improved. And (3) the sewage enters a secondary biochemical tank, the biological membrane utilizes degradable organic matters to carry out denitrification reaction under the anoxic condition, the residual carbon source is removed under the aerobic condition, and COD and TN in the water are further reduced to reach the standard and be discharged.
Optionally, anaerobic treatment may be further included before the step S100: the landfill leachate is homogenized by the regulating tank and then enters an anaerobic tank to degrade macromolecular organic matters and consume high-concentration organic carbon, so that favorable water inlet conditions are created for subsequent denitrification treatment.
The anaerobic treatment specifically comprises the following steps: an anaerobic tank is arranged between the regulating tank and the denitrification reactor, the garbage percolate is pumped into the anaerobic tank by a pump after being homogenized by the regulating tank, and easily degradable macromolecular organic matters in the garbage percolate are degraded under the action of anaerobic bacteria. The step can consume high-concentration organic carbon, preliminarily reduce the COD of the percolate, lighten the organic pollution of the percolate to a denitrification reactor, particularly the pollution to a biological membrane, in addition, the denitrification reactor contains various strains, and the lower concentration of the easily degradable organic carbon can prevent denitrifying bacteria in the reactor from excessively competing for anaerobic ammonium oxidation bacteria to form dominant strains, thereby creating favorable water inlet conditions for subsequent denitrification treatment.
Optionally, the removal load of the organic matter volume in the anaerobic tank is 0.6-1.5kg COD/(m) 3 ·d) According to different COD concentrations of the landfill leachate, the retention time of the landfill leachate in the anaerobic tank is 3-15 days, and preferably, the COD concentration of the effluent of the anaerobic tank is 200-2000mg/L.
Optionally, the step S100 specifically includes the following steps:
s101: a first biofilm carrier is arranged in an aerobic zone of the denitrification reactor, a second biofilm carrier is arranged in an anaerobic zone, ammonia oxidizing bacteria and nitrite oxidizing bacteria are attached to the first biofilm carrier, and anaerobic ammonia oxidizing bacteria and denitrifying bacteria are attached to the second biofilm carrier;
s102: the garbage percolate enters an aerobic zone of a denitrification reactor, is subjected to short-cut nitrification under the action of ammonia oxidizing bacteria to generate nitrite nitrogen, and is subjected to nitrification under the action of nitrite oxidizing bacteria;
s103: and (3) allowing the landfill leachate to enter an anaerobic zone, further converting part of nitrite nitrogen and the other part of ammonia nitrogen generated in the step S102 into nitrogen under the action of anaerobic ammonia oxidizing bacteria, and converting the nitrite nitrogen or nitrate nitrogen generated in the step S102 into nitrogen under the action of denitrifying bacteria to finish the removal of total nitrogen.
The principle of the S100 step is as follows: (1) ammonia oxidizing bacteria and nitrite oxidizing bacteria are arranged in an aerobic zone, a short-cut nitrification process mainly occurs, ammonia nitrogen in the landfill leachate generates nitrite nitrogen under the action of the ammonia oxidizing bacteria and is used as a substrate for anaerobic ammonia oxidation in the next step, and the ammonia oxidizing bacteria are aerobic autotrophic bacteria and are arranged in the aerobic zone to ensure the efficient conversion of the ammonia oxidizing bacteria; (2) in the nitrification process, nitrite nitrogen is converted into nitrate nitrogen under the action of nitrite oxidizing bacteria, so that raw materials are provided for denitrifying bacteria, and the appropriate content of nitrite nitrogen and nitrate nitrogen can be obtained by controlling the nitrification process; (3) anaerobic ammonia oxidizing bacteria and denitrifying bacteria are arranged in the anaerobic zone, the anaerobic ammonia oxidizing bacteria are combined with ammonia nitrogen and nitrite nitrogen to be converted into nitrogen, and meanwhile, a part of nitrate nitrogen is generated; (4) denitrifying bacteria are anaerobic heterotrophic bacteria, organic matters of landfill leachate are used as a carbon source, nitrate nitrogen and nitrite nitrogen generated in the three steps are used as substrates, denitrification and short-range denitrification are carried out, and residual nitrogen is removed or nitrate nitrogen is converted into nitrogen nutrition for self use.
The denitrification reactor has various bacteria, different bacteria are suitable for growing and proliferating and the environmental conditions of effective action stages are different, for example, although an aerobic zone and an anaerobic zone are divided, nitrite nitrogen is consumed by nitrification in the aerobic zone to a certain extent, which is not desirable in the invention, and pure ammonia oxidizing bacteria are obtained, which is technically difficult and cost-free, so that the reasonable control of nitrification of nitrite oxidizing bacteria is a technical difficulty; for another example, the method explores suitable reaction conditions to enable the anaerobic ammonium oxidation bacteria and the denitrifying bacteria in the anaerobic zone to achieve higher conversion efficiency. In a word, exploring a suitable process method to enable multiple processes of shortcut nitrification, denitrification, shortcut denitrification and anaerobic ammonia oxidation in the denitrification reactor to achieve higher efficiency of synergistic denitrification is also a technical difficulty.
Optionally, in order to solve the technical problem, the invention provides a denitrification reactor, which comprises an aerobic zone, an anaerobic zone and a biofilm carrier, wherein the biofilm carrier is a biological rotating disc, and a rotating shaft at the center of the biological rotating disc is parallel to the axial direction of the denitrification reactor; the biofilm carriers comprise a first biofilm carrier and a second biofilm carrier, the first biofilm carrier is arranged in the aerobic zone and is attached with ammonia oxidizing bacteria and nitrite oxidizing bacteria, and the second biofilm carrier is arranged in the anaerobic zone and is attached with anaerobic ammonia oxidizing bacteria and denitrifying bacteria; through holes are uniformly distributed on the biological rotating disc.
Optionally, a water pump is arranged between the aerobic zone and the anaerobic zone and used for inputting the percolate which completes the short-cut nitrification process into the anaerobic zone; a partition plate is arranged between the aerobic zone and the anaerobic zone, the liquid level of the aerobic zone is lower than that of the anaerobic zone, preferably, the liquid level of the aerobic zone is not higher than the central rotating shaft of the biological rotating disk, and the liquid level of the anaerobic zone is not higher than the top of the biological rotating disk.
Optionally, an aeration device is arranged at the bottom of the aerobic zone to provide oxygen for percolate in the aerobic zone, and an exhaust port is arranged at the top of the aerobic zone.
The denitrification reactor is designed in a targeted way by utilizing the advantages of the biological rotating disk of attaching and distributing the biological membrane and the characteristic of rotation between the waste water and the air, and the biological rotating disk is arranged in the aerobic zone and the anaerobic zone. In the aerobic zone, the leachate submerges part of the biological rotating disc, and a double oxygen supply environment is formed through an aeration device in the leachate and a space above the leachate, so that the biological treatment efficiency of aerobic bacteria is improved, meanwhile, the biological rotating disc is favorable for forming a biological film with a large specific surface area, and in the rotating process, the water disturbance is increased, and the contact of dissolved oxygen and pollutants with the biological film is promoted. In the anaerobic zone, the leachate submerges most of the area of the biological rotating disk, anaerobic ammonia oxidation and denitrification are carried out in the water body, and the anaerobic treatment efficiency is improved by means of the form and the rotation advantages of the biological rotating disk.
Optionally, the lateral wall that aerobic zone intake the side is equipped with the water inlet, and the shower is connected to the water inlet, the shower is established on the inner wall that aerobic zone intake the side and perpendicular to rivers direction, from the top down equipartition shower nozzle on the shower, and landfill leachate evenly sprays the biological rotating disc to first biomembrane carrier through the shower.
Optionally, the first biofilm carrier comprises a plurality of rotating biological discs, the porosity of the rotating discs is 40% -60%, each rotating disc is provided with a biofilm in a biofilm formation mode, and the abundance of ammonia oxidizing bacteria on the surfaces of the rotating discs is higher than that of nitrite oxidizing bacteria. The quantity of the biological rotating discs is changed according to the ammonia nitrogen load of the landfill leachate.
The design of the bacteria distribution mode ensures that nitrite oxidizing bacteria consume less nitrite nitrogen, converts ammonia nitrogen into nitrite nitrogen with proper concentration and provides a substrate with proper concentration for the anaerobic ammonia oxidation process of the anaerobic zone.
Optionally, the second biofilm carrier includes a plurality of rotating discs, the porosity of the rotating discs is 30% -40%, each rotating disc is provided with a biofilm in a biofilm formation mode, the total abundance of the anammox bacteria on the rotating disc is greater than that of the denitrifying bacteria, and the abundance of the denitrifying bacteria on the surface of the rotating disc is greater than that of the anammox bacteria.
Optionally, the rotating speeds of the plurality of biological rotating discs of the second biological membrane carrier gradually decrease from the water inlet side to the water outlet side, and preferably, the rotating speed of each rotating disc is 5% -10% slower than that of the previous rotating disc.
According to the bacteria distribution mode and the rotating speed design of the rotating disc, the porosity of the first biological membrane carrier is larger than that of the second biological membrane carrier, so that inflow water containing more pollutants can smoothly pass through the first biological membrane carrier, the first biological membrane carrier is prevented from being blocked, meanwhile, the specific surface area of the second biological membrane carrier can be increased, the bacteria hanging amount is increased, and the efficiency of an anaerobic treatment stage is improved; anaerobic ammonia oxidation bacteria are distributed in the biological rotating disc, sewage which is input from an aerobic area and is subjected to short-cut nitrification is treated, nitrate nitrogen generated in the anaerobic ammonia oxidation process and nitrite nitrogen which cannot be degraded continuously move to the surface of the rotating disc for a second time, and the nitrate nitrogen and the nitrite nitrogen are treated by denitrifying bacteria and are denitrified in a synergistic manner; the rotating speed of the rotating disc of the anaerobic zone is designed, because the flow rate of percolate entering the anaerobic zone is low, the rotating disc close to the aerobic zone is high in rotating speed, disturbance is increased, and the subsequent rotating disc does not need to be overlarge in rotating speed because mass transfer effect can be provided by generated nitrogen.
And the top and the bottom of the anaerobic zone are both provided with exhaust ports for exhausting nitrogen for treatment and conversion. A water outlet is arranged on the side wall of the water outlet side of the anaerobic zone, and the leachate after denitrification treatment is output to the filtering unit.
Optionally, the pH of the aerobic zone is 6.5-7.5; the concentration of dissolved oxygen in the anaerobic zone is 0.1-2mg/L, and the pH value is 7-9. The nitrogen removal load of the denitrification reactor is 0.1-10 kg/(m) 3 D) hydraulic retention time of 1 to 20 days. The denitrification contribution of the anaerobic zone accounts for 30-80% of the denitrification reactor, and the quantity, the rotating speed and the pH value of the biological rotating discs of the aerobic zone and the anaerobic zone are mainly adjusted.
Optionally, the reaction temperature in the denitrification reactor is 25-35 ℃.
Optionally, the COD concentration of the effluent of the anaerobic tank is 200-2000mg/L, and the too high COD concentration can aggravate the aging of the biological rotating disk biofilm and also provide more carbon sources for denitrifying bacteria, so that more denitrifying bacteria and anaerobic ammonium oxidation bacteria compete for substrates and become dominant bacteria.
The preparation method uses the denitrification reactor, utilizes the structural characteristics of the denitrification reactor to orderly carry out nitrification, denitrification and anaerobic ammonia oxidation, simultaneously combines the multi-dimensional conditions of the porosity, the rotating speed, the bacteria distribution, the pH value and the dissolved oxygen concentration of the biological rotating discs of the aerobic zone and the anaerobic zone, and provides different growth environments and hydraulic conditions for different bacteria, so that the multiple bacteria have synergistic effect and can efficiently denitrify and remove most of ammonia nitrogen in the landfill leachate.
Alternatively, the ammonia oxidizing bacteria are selected from the group consisting of Nitrosomonas, nitrosococcus, nitrosospira, etc., the nitrite oxidizing bacteria are Nitrospira, nitrobacter, etc., the anammox bacteria are selected from the group consisting of Brocadia, jettenia, kuenenia, scandina, anammoxima, anammoxoglobus, etc., and the denitrifying bacteria are selected from the group consisting of Thauera, flavobacterium, ignavibacter, comamoadaceae, xanthomonadaceae, etc.
Optionally, the filtering unit in the step S200 is an ultrafiltration unit, and the sludge of the denitrification reactor is retained to perform sludge-water separation, so that a sludge sedimentation tank is not required to be provided, the concentration of suspended solids in the effluent can be reduced, and no concentrated solution is generated.
Optionally, the pore diameter of the ultrafiltration unit is 1-50nm, the operating pressure is 0.1-0.6Mpa, and the permeation flux is 1-100L/(m) 2 ·h)。
The denitrification reactor, namely the COD of the ultrafiltration effluent after primary biochemical treatment is 200-2000mg/L, the total nitrogen is 100-500mg/L, most of the COD is organic matters which are difficult to degrade, and further treatment is needed.
The electrochemical advanced oxidation reactor in the step S300 comprises a plurality of electrolytic cell degradation units and circulating pumps, wherein an anode and a cathode are arranged in each degradation unit, and filtered water circularly passes through each electrolytic cell degradation unit in a reciprocating manner under the action of the circulating pumps to continuously degrade organic matters.
Optionally, the current density applied in the electrolysis process is 2-10 times of the calculated limit current density, the electrolysis time is 0.2-5h, and the balance between the COD degradation current efficiency and the electrolysis time can be obtained, namely, the effective current efficiency is improved in the shortest possible time, and the occurrence of side reactions is reduced.
The limiting current density (I) lim ) Calculated from the formula:
I lim ＝4Fk f COD
wherein F is the Faraday constant (96485C/mol), k f Is the contaminant mass transfer coefficient (m/s).
Optionally, the anode is made of boron-doped diamond and has stable property, high oxygen evolution overpotential and long service life; the cathode is made of stainless steel, and is stable in property, cheap and easy to obtain.
The principle of electrochemical advanced oxidation is as follows: under the action of electrolysis, the organic matters which are difficult to degrade in the landfill leachate are converted into degradable organic matters and even completely mineralized into CO 2 And H 2 O, thereby further reducing COD in the leachate; organic matters are adsorbed on the surface of the anode and are directly degraded through an electron transfer reaction on the surface of the anode; secondly, in a high oxygen evolution overpotential anode potential region, high-valence oxides can be formed on the surface of the anode, meanwhile, the electrode electrolyzes water to generate strong oxidizing substances such as hydroxyl free radicals (OH) and the like, and the active oxygen can lead pollutants to be indirectly oxidized and degraded into low-toxicity or non-toxicity micromolecule intermediate products and even be completely mineralized; in addition, the salt effect of a large amount of chloride ions in the landfill leachate also has a degradation effect on organic matters in water. The combined action of the three promotes the degradation efficiency of organic matters in the electrochemical process, further reduces the COD concentration and improves the biodegradability. In addition, the electrochemical process can not only convert and degrade COD, but also is very effective in removing chroma. The direct oxidation and the free radical indirect oxidation of the anode in the electrolysis process can convert the residual ammonia nitrogen in the water into nitrate nitrogen with high valence state, the nitrate nitrogen is left for the treatment of a secondary biochemical tank, and the salt effect of chloride ions is used for indirectly oxidizing the ammonia nitrogen into nitrogen.
The current density and the electrolysis time cannot meet the requirement that organic matters in the leachate are directly mineralized to reach the standard to be discharged, and the mode has high energy consumption and increases the operation cost; but converts most of the refractory organic matters in the filtered water into degradable organic matters to be treated in a subsequent secondary biochemical tank.
Further optionally, the electrolysis treatment is stopped for a period of time selected from the group consisting of COD in the water and BOD produced by the conversion 5 Until the difference is less than 100mg/L, BOD 5 At the second-stage biochemical poolCarbon source is provided in the process and is removed, so that energy consumption in the electrolytic process and carbon source added in the secondary biological treatment are saved.
The step S400 specifically includes: and (3) feeding electrolyzed effluent into a secondary biochemical tank, wherein the nitrogen of the landfill leachate almost completely exists in the form of nitrate nitrogen, the secondary biochemical tank is a biomembrane A/O tank, intermittent aeration is performed to alternately form an anoxic environment and an aerobic environment, the biomembrane performs denitrification reaction by utilizing degradable organic matters obtained by conversion in the step S300 under the anoxic condition, and residual carbon sources are removed under the aerobic condition, so that COD (chemical oxygen demand) and TN (total nitrogen) in water are further reduced, and the waste leachate is discharged after reaching the standard.
Through the electrochemical advanced oxidation process of S300, the residual nitrogen of the landfill leachate entering the secondary biochemical tank almost completely exists in the form of nitrate nitrogen, and denitrification reaction is performed in the secondary biochemical tank, so that compared with the traditional secondary biochemical treatment technology of the landfill leachate, the aeration energy consumption is saved.
Optionally, the secondary biochemical pond is provided with suspended fillers, and the running time ratio of oxygen deficiency to oxygen deficiency (2-23) is 1, preferably, the running time ratio of oxygen deficiency to oxygen deficiency (10-18) is 1.
Optionally, a carbon source is added in the aerobic stage, and the nitrogen loss amount of the landfill leachate reaching the discharge standard is calculated to obtain the content of residual nitrogen, so that the ratio of the degradable organic matters to the content of the residual nitrogen in the landfill leachate is (3-7): 1 after the carbon source is added.
The traditional method for treating the landfill leachate is to add a carbon source and perform a heterotrophic denitrification process in a primary biochemical treatment stage, the treatment method disclosed by the invention greatly saves the addition of the carbon source, reduces the energy consumption and saves the operation cost, and generally, after the landfill leachate is treated by a secondary biochemical tank, the COD (chemical oxygen demand), total nitrogen and ammonia nitrogen contents can reach the discharge standard.
Optionally, the step S400 may further include the following steps:
s500: coagulation: adding a coagulant into the effluent of the secondary biochemical tank to remove the total phosphorus in the sewage to obtain a coagulation mixed solution;
s600: and (3) precipitation: pumping the mixed liquid into a sedimentation tank for mud-water separation to obtain phosphorus-containing sludge and supernatant;
s700: activated carbon adsorption: the supernatant automatically overflows to an active carbon filter bed, and the effluent of the secondary biochemical tank is purified by utilizing the adsorption performance of the active carbon, so that the final effluent can stably and continuously reach the discharge standard.
Optionally, the coagulant is polyaluminium chloride, the adding amount (measured by L/d) is 0.01-0.05 time of the phosphorus removal amount (measured by g/d), the water and the coagulant are uniformly mixed and then react and flocculate, and the treatment time is 5-40min.
Optionally, the precipitation time in the step S600 is 1-5h.
Optionally, in the step S700, the filling rate of the activated carbon filter bed is 60% to 80%, the hydraulic retention time is 40 to 90min, and the activated carbon has a long service life and a low replacement frequency because the treatment target is relatively clean.
Compared with the prior art, the invention has the following technical advantages:
1. compared with the traditional nitrification-denitrification process, the denitrification process adopting anaerobic ammonia oxidation as the core reduces the energy consumption of blast aeration, mixed liquid reflux and the like, and the total electricity consumption is reduced by 50-60 percent; in the process section, additional carbon source is not needed for denitrification; the autotrophic anammox bacteria grow slowly, the sludge yield can be reduced by about 50 percent, and the subsequent sludge treatment cost is saved.
2. In the electrochemical advanced oxidation stage, reasonable current density is adopted, the balance of COD degradation current efficiency and electrolysis time is sought, and side reactions are reduced; in addition, the complete mineralization of the organic matter is not pursued at this stage, and COD in the water and BOD generated by conversion are used 5 The difference value is less than 100mg/L and is taken as the end point of the electrolytic reaction, thereby greatly saving the energy consumption.
3. The degradable organic matter obtained by the electrochemical advanced oxidation method is treated and removed by a subsequent secondary biochemical pond, and can be used as a carbon source for secondary biochemical denitrification, so that the energy consumption and the carbon source addition are saved; on the whole, compared with the traditional biological denitrification, the treatment method saves 60 to 85 percent of carbon source addition.
4. The treatment method of the invention has no generation of concentrated solution, reasonable process design of the system, short flow and low operation cost.
Drawings
FIG. 1 is a process flow chart of the treatment method for achieving the full amount of landfill leachate according to the invention.
FIG. 2 is a schematic view of the denitrification reactor.
In the attached figure, 1-an aerobic zone, 2-an anaerobic zone, 3-a first biomembrane carrier, 4-a second biomembrane carrier, 5-a clapboard, 6-a spray pipe and 7-an aeration device.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The ammonia oxidizing bacteria, nitrite oxidizing bacteria, anammox bacteria, brocadia and Jettenia bacteria, and denitrifying bacteria, thauera and Flavobacterium bacteria, in the following examples and comparative examples were a combination of nitromonas, nitrobacter, and nitrobacter.
Example 1
The implementation adopts fresh landfill leachate of a certain landfill site to generate 300m of landfill leachate every day 3 The water quality characteristics of the landfill leachate are as follows: COD concentration 3000mg/L, BOD 5 The concentration is 1800mg/L, the ammonia nitrogen concentration is 140mg/L, the nitrate nitrogen concentration is 0.9mg/L, the total nitrogen concentration is 1600mg/L, the total phosphorus concentration is 16mg/L, and the pH value is 8.4.
A treatment method for achieving the full quantity of landfill leachate, the process flow of which is shown in figure 1, comprises the following steps:
s100: the front end of the process flow is provided with an adjusting tank and an anaerobic tank, the garbage percolate is homogenized by the adjusting tank and then pumped into the anaerobic tank by a pump, and easily degradable macromolecular organic matters in the garbage percolate are degraded as much as possible under the action of anaerobic bacteria, so that high-concentration organic carbon is consumed, and favorable water inlet conditions are created for subsequent denitrification treatment;
the effective volume of the anaerobic tank is 1200m 3 The retention time of water conservancy is 4d, and the removal load of the organic matter volume is 0.6kg COD/(m) 3 D) COD of the effluent of the anaerobic tankThe concentration is 600mg/L;
s200: a first biofilm carrier is arranged in an aerobic zone of the denitrification reactor, a second biofilm carrier is arranged in an anaerobic zone, ammonia oxidizing bacteria and nitrite oxidizing bacteria are attached to the first biofilm carrier, and anaerobic ammonia oxidizing bacteria and denitrifying bacteria are attached to the second biofilm carrier; the effluent of the anaerobic tank enters an aerobic zone of a denitrification reactor, is subjected to short-cut nitrification under the action of ammonia oxidizing bacteria to generate nitrite nitrogen, and is subjected to nitrification under the action of nitrite oxidizing bacteria; the garbage percolate enters an anaerobic zone, an anaerobic ammonia oxidation process, a short-range denitrification process and a denitrification process are respectively carried out under the action of anaerobic ammonia oxidation bacteria and denitrifying bacteria, and the nitrite nitrogen generated in the last step is further converted into nitrogen to be removed;
the aerobic zone in the step S200 consumes alkalinity, sodium hydroxide needs to be supplemented in time, and the pH value of the aerobic zone is adjusted to 6.5-7.5; the anaerobic zone generates alkalinity, hydrochloric acid is added when necessary, and the pH value is adjusted to 7-9, so as to be beneficial to the continuous biochemical reaction; the dissolved oxygen concentration of the anaerobic zone is controlled to be 0.5-2mg/L by adjusting the aeration quantity of the aerobic zone. The effective volume of the denitrification reactor is 3000m 3 The retention time of water conservancy is 10 days, and the nitrogen removal load is 0.12 kg/(m) 3 D); the reaction temperature in the denitrification reactor is 35 ℃;
s300: after the treatment of the denitrification reactor, the effluent enters a filtering unit, namely an ultrafiltration unit, and the sludge of the denitrification reactor is intercepted for mud-water separation, so that a sludge sedimentation tank is avoided, and the concentration of suspended matters in the effluent is also reduced;
the aperture of the ultrafiltration unit is 50nm, the operating pressure is 0.4MPa, and the permeation flux is 80L/(m) 2 H) ultrafiltration membrane area of 190m 2 ；
The denitrification reactor, namely the COD of the ultrafiltration effluent after the primary biochemical treatment is 450mg/L, the total nitrogen is 400mg/L, most of the COD is organic matters which are difficult to degrade, and the further treatment is needed;
s400: the ultrafiltration effluent enters an electrochemical advanced oxidation reactor, and the nondegradable organic matters are converted into degradable organic matters by utilizing direct oxidation and indirect oxidation ways, so that the COD concentration is reduced, and the biodegradability of the leachate is improved;
the electrochemical advanced oxidation reactor comprises 10 electrolytic cell degradation units and a circulating pump, wherein an anode and a cathode are arranged in each degradation unit, and the ultrafiltration effluent passes through each electrolytic cell degradation unit in a circulating and reciprocating manner under the action of the circulating pump to continuously degrade organic matters; the boron-doped diamond electrode is used as an anode, the stainless steel electrode is used as a cathode, and the area of the single-side polar plate is 0.4m 2 The distance between the polar plates is 0.5cm, and the applied current density is 80mA/cm 2 The current density applied in the electrolysis process is 10 times of the calculated limit current density, the sewage flow rate is 0.06m/s, and the electrolysis time is 1h;
when the electrolysis treatment is stopped, the COD in the water and the BOD generated by the conversion 5 The difference is 70mg/L;
s500: the electrolyzed effluent enters a secondary biochemical tank, at the moment, the nitrogen of the landfill leachate almost completely exists in the form of nitrate nitrogen, the secondary biochemical tank is a biomembrane A/O tank, a biomembrane method is adopted, the intermittent aeration is performed to alternately form an anoxic environment and an aerobic environment, the intermittent aeration duration is 1h every 10h, the running time ratio of the anoxic environment to the aerobic environment is 10, an external carbon source (acetic acid) is adjusted to the ratio of the degradable organic matter to the residual nitrogen content is 3:1, the biomembrane performs denitrification reaction by utilizing the degradable organic matter obtained by the conversion in the step S400 under the anoxic condition, the residual carbon source is removed under the aerobic condition, the COD and TN in the water are further reduced, and the COD and TN reach the standard and are discharged;
effective volume of secondary biochemical reactor 1200m 3 Hydraulic retention time 4d, nitrogen removal load 0.1 kg/(m) 3 ·d)；
S600: the effluent of the secondary biochemical tank is mixed with a coagulant by using a dosing pump, the required phosphorus removal amount is 4800g/d, the dosing amount of the coagulant polyaluminium chloride (PAC) is 0.016 times of the required phosphorus removal amount, namely 78L/d, the reaction time is 10min, and the total phosphorus in the sewage is mainly removed.
S700: pumping the mixed liquid into a sedimentation tank for mud-water separation, wherein the effective volume of the sedimentation tank is 25m 3 The retention time is 2 hours, and supernatant fluid and phosphorus-containing sludge are obtained through separation;
s800: the supernatant automatically overflows to an active carbon filter bed, and the effluent of the secondary biochemical tank is purified by utilizing the adsorption performance of the active carbon, so that the final effluent can stably and continuously reach the discharge standard;
the effective volume of the activated carbon filter bed is 8m 3 The filling rate of the activated carbon is 70 percent, and the hydraulic retention time is 40min.
In the step S200 of this embodiment, the denitrification reactor provided by the present invention is used, the denitrification reactor includes an aerobic zone 1, an anaerobic zone 2, and a biofilm carrier, the biofilm carrier is a biological rotating disk, and a rotating shaft at the center of the biological rotating disk is parallel to the axial direction of the denitrification reactor; the biofilm carriers comprise a first biofilm carrier 3 and a second biofilm carrier 4, the first biofilm carrier is arranged in the aerobic zone and is attached with ammonia oxidizing bacteria and nitrite oxidizing bacteria, and the second biofilm carrier is arranged in the anaerobic zone and is attached with anaerobic ammonia oxidizing bacteria and denitrifying bacteria; through holes are uniformly distributed on the biological rotating disc.
A water pump (not shown) is arranged between the aerobic zone 1 and the anaerobic zone 2 and is used for inputting percolate which completes the short distance nitration process into the anaerobic zone 2; a partition plate 5 is arranged between the aerobic zone 1 and the anaerobic zone 2, the liquid level of the aerobic zone 1 is lower than that of the anaerobic zone 2, specifically, the liquid level of the aerobic zone 1 is equal to the height of a central rotating shaft of the biological rotating disk, and the liquid level of the anaerobic zone 2 is equal to the height of the top of the biological rotating disk.
Have 1 lateral wall of intaking side in oxygen district to be equipped with the water inlet, shower 6 is connected to the water inlet, and shower 6 is established on the inner wall of oxygen district's side of intaking and perpendicular to rivers direction, from the top down equipartition shower nozzle on shower 6, and landfill leachate evenly sprays the rotating biological disk to first biomembrane carrier 3 through the shower.
The first biological film carrier 3 comprises three biological rotating discs, the porosity of the rotating discs is 60 percent, each rotating disc is provided with a biological film in a film hanging mode, and the abundance of ammonia oxidizing bacteria of the rotating discs is 4.7 multiplied by 10 10 The abundance of copies/g VSS and nitrite oxidizing bacteria is 8.3 multiplied by 10 9 copies/g VSS, and the abundance of ammonia oxidizing bacteria on the surface of the rotating disc is higher than that of nitrite oxidizing bacteria. Four aeration heads 7 are arranged at the bottom of the aerobic zone 1 and used for providing oxygen, and an exhaust port is arranged at the top of the aerobic zone.
The second biofilm carrier 4 comprises three biological rotating discs with a porosity of 40% per discThe rotary discs are provided with biological membranes in a membrane hanging mode, and the abundance of anaerobic ammonium oxidation bacteria on the rotary discs is 2.1 multiplied by 10 11 copies/g VSS, abundance of denitrifying bacteria 6.7 × 10 10 The copes/g VSS, and the abundance of the denitrifying bacteria on the surface of the rotating disc is greater than that of the anaerobic ammonium oxidation bacteria. The rotating speed of the biological rotating discs of the second biological film carrier is gradually reduced from the water inlet side to the water outlet side, and the rotating speed of each rotating disc is 10% slower than that of the previous rotating disc. And exhaust ports are arranged at the top and the bottom of the anaerobic zone 2 and used for exhausting nitrogen converted by ammonia nitrogen treatment. A water outlet is arranged on the side wall of the water outlet side of the anaerobic zone, and the leachate after denitrification treatment is output to the filtering unit.
The processing effect and the running cost of this example were analyzed as shown in tables 1 and 2.
TABLE 1 Effect of the treatment of each procedure
Figure BDA0002895368170000111
Note: COD Cr The unit of ammonia nitrogen, total nitrogen and total phosphorus is mg/L, and the unit of chromaticity is dimensionless.
TABLE 2 running cost analysis (Yuan/m) 3 )
Figure BDA0002895368170000112
Note: the medicament consumption comprises an external carbon source, PAC, a filter membrane cleaning agent, an active carbon regeneration medicament and the like, and the electricity charge is calculated according to 0.8 yuan/kwh.
As can be seen from the analysis of tables 1 and 2, the effluent of the system after the landfill leachate treatment can meet the discharge requirement of the pollution control Standard for municipal solid waste landfills (GB 16889-2008), and the comprehensive treatment cost of the process is 56.1 yuan/m 3 (without water cost, labor, maintenance, etc.). The ton water treatment cost of the current membrane method is 30-80 yuan/m 3 (treatment without concentrate) and the cost for treating the concentrate is 200 Yuan/m 3 (based on the water yield of the concentrated solution of 60%). The treatment method for achieving the full quantity of landfill leachate to the standard can ensure that the system is stable, can achieve the standard and can continuously run, and does not haveCompared with the traditional membrane method, the method has great technical and economic advantages and brings good economic, social and environmental benefits.
Example 2
The landfill leachate that this implementation adopted is the same as embodiment 1, and first biomembrane carrier 3 includes three biological rotating discs in this embodiment, and the porosity of carousel is 40%, and second biomembrane carrier 4 includes three biological rotating discs, and the porosity of carousel is 30%, and the rotational speed of the biological rotating disc of second biomembrane carrier slows down from the side of intaking to the side of giving out water gradually, and the rotational speed of every carousel is 5% slower than the preceding carousel. The other steps of this example are the same as example 1.
Example 3
The landfill leachate used in this example was the same as in example 1, and the abundance of ammonia oxidizing bacteria in the rotating disk of the first biofilm carrier was 8.3 × 10 9 The abundance of copies/g VSS and nitrite oxidizing bacteria is 4.7 multiplied by 10 10 The nitrite oxidizing bacteria on the surface of the first biological membrane carrier are more abundant than the ammonia oxidizing bacteria; the abundance of the anaerobic ammonia oxidizing bacteria on the surface of the second biological membrane carrier is greater than that of the denitrifying bacteria. The other steps of this example are the same as example 1.
Example 4
The landfill leachate used in this example was the same as in example 1, the reaction temperature in the denitrification reactor was 25 ℃, and the other steps in this example were the same as in example 1.
Example 5
The landfill leachate adopted in the implementation is the same as that in the embodiment 1, the current density applied in the electrolysis process in the step S400 is 2 times of the calculated limit current density, the electrolysis time is 5h, and other steps in the embodiment are the same as those in the embodiment 1.
Example 6
The landfill leachate adopted in the implementation is the same as that in the embodiment 1, the secondary biochemical tank is a biomembrane A/O tank, a biomembrane method is adopted, intermittent aeration is carried out to alternately form an anoxic environment and an aerobic environment, the running time ratio of anoxic to aerobic environment is 18, and other steps in the implementation are the same as those in the embodiment 1.
Example 7
The landfill leachate adopted in the implementation is the same as that in the embodiment 1, the external carbon source (acetic acid) in the secondary biochemical pond is adjusted to the ratio of the degradable organic matter to the residual nitrogen content of 7:1, and other steps in the embodiment are the same as those in the embodiment 1.
Example 8
The landfill leachate used in this embodiment is the same as that used in embodiment 1, and a general denitrification reactor, that is, an aerobic zone and an anaerobic zone, are used instead of the denitrification reactor described in embodiment 1, and both zones use activated sludge corresponding to bacteria, and a spray pipe and a biological rotating disk are not provided, and other steps of this embodiment are the same as those of embodiment 1.
Example 9
The implementation adopts the leachate of a certain sealed landfill for ten years, and the leachate belongs to aged landfill leachate. Landfill leachate collected and treated by treatment station every day is 80m 3 . The water quality characteristics of the landfill leachate are as follows: COD concentration 850mg/L, BOD 5 The concentration is 160mg/L, the ammonia nitrogen concentration is 1200mg/L, the nitrate nitrogen concentration is 5mg/L, the total nitrogen concentration is 1250mg/L, the total phosphorus concentration is 10mg/L, and the pH value is 8.2.
The treatment method and the flow for the aged landfill leachate in the embodiment are basically the same as those in the embodiment 1, and the differences are as follows: because the concentration of degradable organic matters in the aged landfill leachate is very low, the anaerobic treatment in the step S100 can be omitted, so that the investment and the operation cost are saved; in step S200, the effective volume of the denitrification reactor taking anaerobic ammonia oxidation technology as core is 800m 3 Water conservancy retention time of 10d and nitrogen removal load of 0.12kg m -3 d -1 (ii) a Step S300 operating pressure of the ultrafiltration unit is 0.4MPa, and permeation flux is 80L m -2 h -1 Ultrafiltration membrane area 50m 2 (ii) a Step S400 electrochemical advanced oxidation process, wherein the area of a single-side polar plate is 1.1m 2 The distance between the polar plates is 0.5cm, and the applied current density is 80mA cm -2 Liquid flow rate of 0.06m s -1 The retention time of the treatment liquid in the device is 16min; step S500, a secondary biochemical pool with an effective volume of 320m 3 The retention time of water conservancy is 4d, and the nitrogen removal load is 0.1kg m -3 d -1 (ii) a Step S600 adding amount of coagulant polyaluminum chlorideIs 11L d -1 Reacting for 10min; step S700 effective volume of sedimentation tank 5.5m 3 The retention time is 2h; step S800 effective volume of activated carbon filter bed 2.7m 3 The filling rate of the activated carbon is 80 percent, and the hydraulic retention time is 90min.
Comparative example 1
The landfill leachate used in this comparative example was the same as in example 1, but did not include the step of treating the landfill leachate with a denitrification reactor, and the other steps in this example were the same as in example 1.
Comparative example 2
The landfill leachate used in this comparative example was the same as in example 1, but did not include the step of treating landfill leachate with an electrochemical advanced oxidation reactor, and the other steps in this example were the same as in example 1.
Table 3 total contaminant removal comparison of examples 1-9 and comparative examples 1-2
Figure BDA0002895368170000131
Figure BDA0002895368170000141
As can be seen from the above table, the treatment method for achieving the full amount of the landfill leachate can better treat the landfill leachate, and anaerobic ammonia oxidation and electrochemical advanced oxidation are the core of the leachate treatment process provided by the invention. Through setting the abundance of various bacteria in the denitrification reactor and the conditions such as the biological rotating disc, the synergistic denitrification of various bacteria is realized, and the total removal rate of ammonia nitrogen can reach 100 percent. By reasonably utilizing the electrochemical oxidation technology and combining the denitrification reactor, the total removal rate of COD is also higher. The treatment method has strong application and popularization values.

Claims (7)

1. A treatment method for achieving the full quantity of landfill leachate is characterized by comprising the following steps:
s100: the garbage leachate is homogenized by a regulating tank and then enters a denitrification reactor, and short-cut nitrification, denitrification, short-cut denitrification and anaerobic ammonia oxidation are performed in the denitrification reactor to realize the synergic denitrification;
s200: after being treated by the denitrification reactor, the effluent enters a filtering unit for mud-water separation, so that the concentration of suspended matters in the effluent is reduced;
s300: filtered water enters an electrochemical advanced oxidation reactor, and refractory organic matters are converted into degradable organic matters by utilizing direct oxidation and indirect oxidation ways, so that the biodegradability of the leachate is improved;
s400: the electrolyzed effluent enters a secondary biochemical tank, and denitrification reaction is carried out by utilizing the degradable organic matters obtained by conversion in the step S300;
the step S100 specifically includes the steps of:
s101: a first biofilm carrier is arranged in an aerobic zone of the denitrification reactor, a second biofilm carrier is arranged in an anaerobic zone, ammonia oxidizing bacteria and nitrite oxidizing bacteria are attached to the first biofilm carrier, and anaerobic ammonia oxidizing bacteria and denitrifying bacteria are attached to the second biofilm carrier;
s102: the effluent of the anaerobic tank enters an aerobic zone of a denitrification reactor, is subjected to short-cut nitrification under the action of ammonia oxidizing bacteria to generate nitrite nitrogen, and is subjected to nitrification under the action of nitrite oxidizing bacteria;
s103: the landfill leachate enters an anaerobic zone, part of nitrite nitrogen and the other part of ammonia nitrogen generated in the step S102 are further converted into nitrogen under the action of anaerobic ammonium oxidation bacteria, and the nitrite nitrogen or nitrate nitrogen generated in the step S102 is converted into nitrogen under the action of denitrifying bacteria to finish the removal of total nitrogen;
the first biological film carrier comprises a plurality of biological rotating discs, the porosity of each rotating disc is 40% -60%, and the abundance of ammonia oxidizing bacteria on the surfaces of the rotating discs is higher than that of nitrite oxidizing bacteria;
the second biological membrane carrier comprises a plurality of biological rotating discs, the porosity of each rotating disc is 30-40%, the total abundance of the anaerobic ammonia oxidizing bacteria on the rotating discs is greater than that of the denitrifying bacteria, and the abundance of the denitrifying bacteria on the surfaces of the rotating discs is greater than that of the anaerobic ammonia oxidizing bacteria;
the rotating speeds of a plurality of biological rotating discs of the second biological film carrier are gradually reduced from the water inlet side to the water outlet side, and the rotating speed of each rotating disc is 5-10% slower than that of the previous rotating disc;
the liquid level height of the aerobic zone is lower than that of the anaerobic zone, the liquid level height of the aerobic zone is not higher than the central rotating shaft of the biological rotating disk, and the liquid level height of the anaerobic zone is not higher than the top of the biological rotating disk.
2. The treatment method as claimed in claim 1, wherein the denitrification reactor comprises an aerobic zone, an anaerobic zone and a biofilm carrier, the biofilm carrier is a biological rotating disc, and a rotating shaft at the center of the biological rotating disc is parallel to the axial direction of the denitrification reactor; the biofilm carriers comprise a first biofilm carrier and a second biofilm carrier, the first biofilm carrier is arranged in the aerobic zone and is attached with ammonia oxidizing bacteria and nitrite oxidizing bacteria, and the second biofilm carrier is arranged in the anaerobic zone and is attached with anaerobic ammonia oxidizing bacteria and denitrifying bacteria; through holes are uniformly distributed on the biological rotating disc.
3. The treatment process of claim 2, wherein the aerobic zone has a pH of 6.5 to 7.5; the dissolved oxygen concentration of the anaerobic zone is 0.1-2mg/L, and the pH value is 7-9; the nitrogen removal load of the denitrification reactor is 0.1-10 kg/(m) 3 D) hydraulic retention time of 1 to 20 days.
4. The treatment method according to claim 2, wherein a water pump is arranged between the aerobic zone and the anaerobic zone and is used for inputting the percolate which completes the short distance nitration process into the anaerobic zone; a partition plate is arranged between the aerobic zone and the anaerobic zone, the liquid level of the aerobic zone is lower than that of the anaerobic zone, the liquid level of the aerobic zone is not higher than the central rotating shaft of the biological rotating disc, and the liquid level of the anaerobic zone is not higher than the top of the biological rotating disc;
the side wall of the water inlet side of the aerobic zone is provided with a water inlet which is connected with a spray pipe, the spray pipe is arranged on the inner wall of the water inlet side of the aerobic zone and is vertical to the water flow direction, spray heads are uniformly distributed on the spray pipe from top to bottom, and the garbage percolate is uniformly sprayed to the biological rotating disc of the first biological membrane carrier through the spray pipe;
the bottom of the aerobic zone is provided with an aeration device for providing oxygen, and the top of the aerobic zone is provided with an exhaust port;
the top and the bottom of the anaerobic zone are provided with exhaust ports for exhausting nitrogen converted by treatment; a water outlet is arranged on the side wall of the water outlet side of the anaerobic zone, and the leachate after denitrification treatment is output to the filtering unit.
5. The treatment method according to claim 1, wherein the electrochemical advanced oxidation reactor in the step S300 comprises a plurality of electrolytic cell degradation units and circulating pumps, each degradation unit is internally provided with an anode and a cathode, and filtered water passes through each electrolytic cell degradation unit in a circulating and reciprocating manner under the action of the circulating pumps to continuously degrade organic matters;
the current density applied in the electrolytic process is 2 to 10 times of the calculated limit current density, and the electrolytic time is 0.2 to 5 h;
the electrolysis treatment is stopped by the COD in the water and the BOD generated by conversion 5 Until the difference is less than 100 mg/L.
6. The processing method according to claim 5, wherein the step S400 specifically comprises: and (3) feeding electrolyzed effluent into a secondary biochemical tank, wherein the secondary biochemical tank is a biomembrane A/O tank, intermittently aerating to alternately form an anoxic environment and an aerobic environment, carrying out denitrification reaction on the biomembrane by using degradable organic matters obtained by conversion in the step S300 under the anoxic condition, removing residual carbon sources under the aerobic condition, and further reducing COD (chemical oxygen demand) and TN (total nitrogen) in the water to ensure that the water is discharged after reaching the standard.
7. The treatment method according to claim 6, wherein the secondary biochemical pond is provided with suspended fillers, and the running time ratio of anoxic to aerobic (2-23) is 1;
and (3) adding a carbon source in an aerobic stage, and calculating the nitrogen loss amount of the landfill leachate reaching the discharge standard to obtain the content of residual nitrogen, so that the ratio of the degradable organic matters to the content of the residual nitrogen in the landfill leachate is (3-7): 1 after the carbon source is added.
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