Device and method for treating late landfill leachate through integration of intermittent aeration/short-range denitrification-anaerobic ammonia oxidation
Technical Field
The invention relates to a device and a method for realizing advanced denitrification of late landfill leachate, belonging to the field of biological treatment of high ammonia nitrogen sewage and sludge.
Background
In recent years, with the increasing production of municipal solid waste, landfill has become the most widely used treatment and disposal method in the world. The leachate generated by landfill has the water quality characteristics of complex components, large water quality and water quantity change, high concentration of organic matters and ammonia nitrogen, imbalance proportion of microorganism nutrient elements and the like, so that the treatment of the leachate becomes one of the unsolved problems in the international range. NH is treated by the traditional biological denitrification process4 +Conversion of-N to N03 -N, and denitrifying N03 -N is converted to nitrogen which escapes from the water. The denitrification stage is shown as N03 -and-N is an electron acceptor, and the organic matter is used as an electron donor to convert ammonia nitrogen into nitrogen to complete biological denitrification. The serious shortage of organic carbon source is a barrier that the denitrification efficiency of the leachate at the late stage cannot be improved, so that the traditional biological denitrification efficiency is only improvedCan reach about 10 percent, and the added organic carbon source can greatly increase the cost of sewage denitrification.
The anaerobic ammonia oxidation technology belongs to an autotrophic nitrogen removal process, does not need an organic carbon source, has low sludge yield and does not need aeration, and is suitable for high ammonia nitrogen wastewater such as low C/N ratio late-stage landfill leachate and the like. The short-cut nitrification/anaerobic ammonia oxidation reactor has ammonia oxidizing bacteria and anaerobic ammonia oxidizing bacteria, and partial NH is generated by the ammonia oxidizing bacteria in the aeration stage4 +Conversion of-N to NO2 -N, residual NH is utilized by anaerobic ammonium oxidation bacteria in the stirring stage4 +N will transfer NO generated by the short-cut nitration stage2 -Conversion of-N to N2And a small amount of NO3 --N. The short-cut nitrification/anaerobic ammonia oxidation reaction system adopts a circulating intermittent aeration mode, partial nitrogen can be removed through aeration/stirring once until the nitrogen in the reactor is completely removed, the process is simple, the operation is convenient, and the efficiency is high. The removal of nitrogen in the shortcut nitrification/anaerobic ammonia oxidation reactor depends on the anaerobic ammonia oxidation action, but a large amount of nitrate nitrogen generated in the anaerobic ammonia oxidation process is the main reason for the effluent not reaching the standard. The problem of high nitrate nitrogen in the anaerobic ammonia oxidation effluent can be effectively solved in the short-cut denitrification process, the anaerobic ammonia oxidation and the short-cut denitrification can be simultaneously carried out in a single reactor, nitrate nitrogen generated by the anaerobic ammonia oxidation is reduced into nitrite nitrogen by short-cut denitrification bacteria, and the generated nitrite nitrogen is further removed by the anaerobic ammonia oxidation, so that the effluent TN concentration can be effectively reduced compared with that of the traditional anaerobic ammonia oxidation process.
At present, the intermittent aeration short-cut nitrification-anaerobic ammonia oxidation/short-cut denitrification-anaerobic ammonia oxidation technology is never applied to the treatment of the late-stage landfill leachate with complex components, large change of water quality and water quantity, high ammonia nitrogen concentration and imbalance of proportion of microorganism nutrient elements.
Disclosure of Invention
The invention provides a device and a method for treating late landfill leachate by intermittent aeration short-range nitrification-anaerobic ammonia oxidation/short-range denitrification-anaerobic ammonia oxidation. The method comprises the following steps: and pumping the late landfill leachate into a shortcut nitrification/anaerobic ammonia oxidation reactor by a peristaltic pump, and controlling the aeration amount to ensure that the dissolved oxygen of the reactor is 0.1-0.5mg/L in the aeration stage, thereby realizing the shortcut nitrification/anaerobic ammonia oxidation reaction. Through the operation mode of aeration/anoxic stirring … … aeration/anoxic stirring cyclic intermittent aeration, nitrite nitrogen generated by short-cut nitrification can be timely utilized by anaerobic ammonia oxidation bacteria, so that nitrite nitrogen residue does not exist in the reactor, wherein aeration is carried out for 30min, and stirring is stopped when the first derivative of a pH curve approaches zero by adopting real-time control on anoxic stirring time; pumping the effluent of the short-cut nitrification/anaerobic ammonia oxidation reactor containing nitrate nitrogen, the other part of late landfill leachate and an external carbon source into the short-cut denitrification/anaerobic ammonia oxidation reactor at the same time, firstly reducing the nitrate nitrogen into nitrite nitrogen by short-cut denitrifying bacteria, and further deeply removing the nitrite nitrogen through anaerobic ammonia oxidation;
the purpose of the invention is realized by the following technical scheme:
the device for treating the late landfill leachate by intermittent aeration short-cut nitrification-anaerobic ammonia oxidation/short-cut denitrification-anaerobic ammonia oxidation comprises a raw water tank (1), a short-cut nitrification/anaerobic ammonia oxidation reactor (2), an intermediate water tank (3), an external carbon source storage tank (4.3) and a short-cut denitrification/anaerobic ammonia oxidation reactor (4);
the raw water tank is provided with a first water outlet (1.1) and a second water outlet (1.2); the short-cut nitrification/anaerobic ammonia oxidation reactor is provided with an air compressor (2.1), a gas flow meter (2.2), an aeration sand head (2.3), a first water inlet (2.5), a first sampling port (2.9), a first water discharge port (2.10), a first stirrer (2.7), a first water inlet peristaltic pump (2.4), a pH/DO real-time monitoring device (2.8) and a first ORP real-time monitoring device (2.6); the short-cut denitrification/anaerobic ammonia oxidation device is provided with a vent pipe (4.6), a second water inlet (4.13), a second water inlet peristaltic pump (4.2), a third water inlet peristaltic pump (4.1), a first return port (4.9), a first return peristaltic pump (4.11), a second return port (4.12), a three-phase separator (4.7), an exhaust port (4.5), an air bag (4.4) and a second water outlet (4.8);
the raw water tank (1) is respectively connected with the shortcut nitrification/anaerobic ammonia oxidation reactor (2) and the shortcut denitrification/anaerobic ammonia oxidation reactor (4) through a first water inlet peristaltic pump (2.4)/a third water inlet peristaltic pump (4.1); a first water discharge port (2.10) of the shortcut nitrification/anaerobic ammonia oxidation reactor is connected with a first intermediate water tank (3), and air is pumped into the shortcut nitrification/anaerobic ammonia oxidation reactor (2) through an air compressor (2.1) and a gas flow meter (2.2) finally through an aeration sand head (2.3); the intermediate water tank (3) is connected with a second water inlet (4.13) of the short-cut denitrification/anaerobic ammonia oxidation reactor through a second water inlet peristaltic pump (4.2); an external carbon source storage tank (4.3) is connected with the short-cut denitrification/anaerobic ammonia oxidation reactor (4); the first reflux opening (4.9) of the short-cut denitrification/anaerobic ammoxidation reactor is connected with the second reflux opening (4.12) through a first reflux peristaltic pump (4.11).
The device is used for carrying out intermittent aeration short-cut nitrification-anaerobic ammonia oxidation/short-cut denitrification-anaerobic ammonia oxidation treatment on the late landfill leachate, and is characterized by comprising the following steps:
1) short-cut nitrification/anaerobic ammonia oxidation sludge and short-cut denitrification anaerobic ammonia oxidation sludge are respectively added into the reactors, and the sludge concentration of mixed liquor of each reactor after the addition is controlled to be 4011-4435mg/L and 4820-5231mg/L respectively.
2) The late landfill leachate in the raw water tank is pumped into a short-range nitrification/anaerobic ammonia oxidation reactor at one time; the short-range nitrification/anaerobic ammonia oxidation reactor controls the aeration rate by adjusting a gas flowmeter, so that the dissolved oxygen of the reactor is maintained at 0.1-0.5mg/L in the aeration stage; each operation period of the short-cut nitrification/anaerobic ammonia oxidation reactor comprises a water inlet unit, a 6-time aeration/anoxic stirring circulation alternate operation unit, a precipitation unit and a water drainage unit. Wherein, each time of aeration is 30min, the anaerobic stirring time adopts real-time control to stop stirring when the first derivative of the pH curve is less than 0.3, the rotating speed of the stirrer is 70r/min, and the water discharge ratio is 30%.
3) And respectively opening a second water inlet peristaltic pump and a third water inlet peristaltic pump to simultaneously pump the nitrate nitrogen-containing wastewater in the intermediate water tank and the late landfill leachate in the raw water tank into the short-cut denitrification/anaerobic ammonia oxidation reactor. And controlling the flow rates of the second and third water inlet peristaltic pumps to be 72mL/h and 6.6mL/h respectively, enabling the wastewater of the short-cut denitrification/anaerobic ammonia oxidation reactor to enter the second reflux port from the first reflux port through the first reflux peristaltic pump, and controlling the flow rate of the first reflux peristaltic pump to be 0.5L/h.
Principle of the technology
The device and the method for treating the advanced landfill leachate by intermittent aeration short-cut nitrification-anaerobic ammonia oxidation/short-cut denitrification-anaerobic ammonia oxidation are characterized in that the advanced landfill leachate is pumped into a short-cut nitrification/anaerobic ammonia oxidation reactor by a peristaltic pump, and the dissolved oxygen of the reactor in the aeration stage is 0.1-0.5mg/L by controlling the aeration amount, so that the short-cut nitrification/anaerobic ammonia oxidation reaction is realized. Through the operation mode of cyclic intermittent aeration of aeration/anoxic stirring, nitrite nitrogen generated by short-cut nitrification can be timely utilized by anaerobic ammonia oxidation bacteria, so that nitrite nitrogen residue does not exist in the reactor, wherein the aeration is carried out for 30min, and the stirring is stopped when the first derivative of a pH curve approaches zero by adopting real-time control on anoxic stirring time; pumping the effluent of the short-cut nitrification/anaerobic ammonia oxidation reactor containing nitrate nitrogen, the other part of late landfill leachate and an external carbon source into the short-cut denitrification/anaerobic ammonia oxidation reactor at the same time, firstly reducing the nitrate nitrogen into nitrite nitrogen by short-cut denitrifying bacteria, and further deeply removing the nitrite nitrogen through anaerobic ammonia oxidation; the invention can realize the purpose of deep denitrification of the late landfill leachate.
The device and the method for treating the advanced landfill leachate by intermittent aeration short-cut nitrification-anaerobic ammonium oxidation/short-cut denitrification-anaerobic ammonium oxidation have the following advantages:
1) the shortcut nitrification reaction and the anaerobic ammonia oxidation process can be carried out in the shortcut nitrification/anaerobic ammonia oxidation reactor, and compared with the traditional shortcut nitrification coupled anaerobic ammonia oxidation two-stage treatment process, the device is simple and easy to operate.
2) The short-cut nitrification of the ammonia oxidizing bacteria can save 60 percent of aeration amount, and the anaerobic ammonia oxidizing bacteria have no N in the metabolic process2O is generated, so the greenhouse gas emission of the process is low.
3) The process can reduce nitrate nitrogen generated by anaerobic ammonia oxidation and remove the nitrate nitrogen in situ, effectively improves the total nitrogen removal rate, and has high reaction rate of short-range denitrification and anaerobic ammonia oxidation and high nitrogen removal load;
4) the short-cut denitrification in the short-cut denitrification/anaerobic ammoxidation reactor only reduces nitrate nitrogen to nitrite nitrogen, so that the consumption of carbon sources is low, and the sludge yield is lower than that of the traditional denitrification process, thereby reducing the energy consumption and the cost of the subsequent sludge treatment.
5) The technology does not need to add an additional medicament, can directly treat the late-stage landfill leachate with high ammonia nitrogen and low carbon nitrogen ratio after domestication, and has simple and clear process and easy management.
Drawings
FIG. 1 is a schematic view of the apparatus of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
The device for treating the late landfill leachate by intermittent aeration short-cut nitrification-anaerobic ammonia oxidation/short-cut denitrification-anaerobic ammonia oxidation comprises a raw water tank (1), a short-cut nitrification/anaerobic ammonia oxidation reactor (2), an intermediate water tank (3), an external carbon source storage tank (4.3) and a short-cut denitrification/anaerobic ammonia oxidation reactor (4);
the raw water tank is provided with a first water outlet and a second water outlet; the short-cut nitrification/anaerobic ammonia oxidation reactor is provided with an air compressor (2.1), a gas flow meter (2.2), an aeration sand head (2.3), a first water inlet (2.5), a first sampling port (2.9), a first water discharge port (2.10), a first stirrer (2.7), a first water inlet peristaltic pump (2.4), a pH/DO real-time monitoring device (2.8) and a first ORP real-time monitoring device (2.6); the short-cut denitrification/anaerobic ammonia oxidation device is provided with a vent pipe (4.6), a second water inlet (4.13), a second water inlet peristaltic pump (4.2), a third water inlet peristaltic pump (4.1), a first return port (4.9), a first return peristaltic pump (4.11), a second return port (4.12), a three-phase separator (4.7), an exhaust port (4.5), an air bag (4.4) and a second water outlet (4.8);
the raw water tank (1) is respectively connected with the shortcut nitrification/anaerobic ammonia oxidation reactor (2) and the shortcut denitrification/anaerobic ammonia oxidation reactor (4) through a first water inlet peristaltic pump (2.4)/a third water inlet peristaltic pump (4.1); a first water discharge port (2.10) of the shortcut nitrification/anaerobic ammonia oxidation reactor is connected with a first intermediate water tank (3), and air is pumped into the shortcut nitrification/anaerobic ammonia oxidation reactor (2) through an air compressor (2.1) and a gas flow meter (2.2) finally through an aeration sand head (2.3); the intermediate water tank (3) is connected with a second water inlet (4.13) of the short-cut denitrification/anaerobic ammonia oxidation reactor through a second water inlet peristaltic pump (4.2); an external carbon source storage tank (4.3) is connected with the short-cut denitrification/anaerobic ammonia oxidation reactor (4); the first reflux opening (4.9) of the short-cut denitrification/anaerobic ammoxidation reactor is connected with the second reflux opening (4.12) through a first reflux peristaltic pump (4.11).
The water used in the specific test of the embodiment is the actual late landfill leachate, the average ammonia nitrogen concentration is 1263mg/L, the average COD concentration is 1516mg/L, and the average alkalinity is 3427mg/L (using CaCO)3Meter). The experimental shortcut nitrification/anaerobic ammonia oxidation reactor adopts sequencing batch SBR, the effective volume is 10L, and the water discharge ratio is 26%; the effective volume of the short-cut denitrification/anaerobic ammoxidation reactor is 2L by adopting an upflow anaerobic sludge blanket reactor (UASB);
the specific operation process is as follows:
1) short-cut nitrification/anaerobic ammonia oxidation sludge and short-cut denitrification anaerobic ammonia oxidation sludge are respectively added into the reactors, and the sludge concentration of mixed liquor of each reactor after the addition is controlled to be 4011-4435mg/L and 4820-5231mg/L respectively.
2) The late landfill leachate in the raw water tank is pumped into a short-range nitrification/anaerobic ammonia oxidation reactor at one time; the short-range nitrification/anaerobic ammonia oxidation reactor controls the aeration rate by adjusting a gas flowmeter, so that the dissolved oxygen of the reactor is maintained at 0.1-0.5mg/L in the aeration stage; each operation period of the short-cut nitrification/anaerobic ammonia oxidation reactor comprises a water inlet unit, a 6-time aeration/anoxic stirring circulation alternate operation unit, a precipitation unit and a water drainage unit. Wherein, each time of aeration is 30min, the anaerobic stirring time adopts real-time control to stop stirring when the first derivative of the pH curve is less than 0.3, the rotating speed of the stirrer is 70r/min, and the water discharge ratio is 30%.
3) And respectively opening a second water inlet peristaltic pump and a third water inlet peristaltic pump to simultaneously pump the nitrate nitrogen-containing wastewater in the intermediate water tank and the late landfill leachate in the raw water tank into the short-cut denitrification/anaerobic ammonia oxidation reactor. And controlling the flow rates of the second and third water inlet peristaltic pumps to be 72mL/h and 6.6mL/h respectively, enabling the wastewater of the short-cut denitrification/anaerobic ammonia oxidation reactor to enter the second reflux port from the first reflux port through the first reflux peristaltic pump, and controlling the flow rate of the first reflux peristaltic pump to be 0.5L/h.
The continuous test results show that:
the process has total nitrogen removal rate and total nitrogen removal rate of 97.4% and 0.24 kg/m under the conditions that the concentration of ammonia nitrogen, total nitrogen and COD in inlet water are 1263mg/L, 1342mg/L and 1516mg/L respectively3d. Water outlet TN<40mg/L, reaching the landfill leachate discharge standard.