Treatment system for wastewater with high ammonia nitrogen and low carbon nitrogen ratio

Abstract

The utility model provides a treatment system for wastewater with high ammonia nitrogen and low carbon nitrogen ratio, which relates to the technical field of wastewater treatment and comprises an aeration sedimentation tank group, a primary denitrification reactor, a water tank, a secondary denitrification reactor and a nitrification tank which are sequentially arranged along the wastewater treatment direction, the aeration sedimentation tank group is used for removing organic matters and suspended matters in the sewage, reducing the concentration of metal ions and adjusting the pH value of the sewage; the primary denitrification reactor is communicated with the aeration sedimentation tank group and is used for carrying out short-cut nitrification reaction and anaerobic ammonia oxidation reaction; the top of the water tank is communicated with the primary denitrification reactor, and the bottom of the water tank is communicated with the secondary denitrification reactor through a first pipeline; the second-stage denitrification reactor is used for carrying out denitrification reaction coupling short-cut denitrification reaction and anaerobic ammonia oxidation reaction, and the second-stage denitrification reactor is provided with a first water outlet communicated with the first pipeline and a second water outlet communicated with the nitrification tank. The treatment system can ensure that high-ammonia-nitrogen low-carbon-nitrogen-ratio wastewater treatment reaches the nanotube standard.

Description

TECHNICAL FIELD

[0001] The utility model relates to wastewater treatment technical field especially is related to a kind of treatment system of high ammonia nitrogen low carbon nitrogen ratio wastewater. BACKGROUND

[0002] High ammonia nitrogen low carbon nitrogen ratio wastewater refers to the wastewater that little organic carbon source is supplied for microorganism to carry out denitrification and ammonia nitrogen concentration is higher.And common high ammonia nitrogen low carbon nitrogen ratio wastewater mainly has the industrial wastewater generated by monosodium glutamate, chemical fertilizer, coal chemical industry etc., the aged garbage leachate generated by landfill site, livestock and poultry breeding anaerobic fermentation wastewater, and dewatering filtrate after sludge anaerobic digestion of urban sewage treatment plant etc., these wastewaters all contain higher concentration ammonia nitrogen.

[0003] At present, traditional nitrification-denitrification denitrification technology is most widely used.However, when treating high ammonia nitrogen low carbon nitrogen ratio wastewater, traditional nitrification-denitrification technology has obvious short board.Firstly, the oxygen supply amount required by nitrification process is large, and energy consumption is high, and the aeration system of traditional sewage treatment plant accounts for about 50%-55% of the total power consumption of sewage treatment plant, and when treating high ammonia nitrogen wastewater, capital investment and energy consumption will increase greatly;Secondly, low carbon nitrogen ratio wastewater is deficient in organic carbon source due to high ammonia nitrogen, and additional carbon source needs to be added to meet the needs of microbial denitrification process, which increases the operation cost and may also cause secondary pollution.

[0004] In view of the above problems, short-cut nitrification-anaerobic ammonia oxidation process is a new biological denitrification technology for treating high ammonia nitrogen low carbon nitrogen ratio wastewater, compared with traditional nitrification-denitrification process, the process can reduce 60% of aeration amount, does not need organic carbon source, and sludge yield is low (about 90% reduction).Therefore, wastewater with high ammonia nitrogen and low carbon nitrogen ratio is suitable for denitrification treatment by short-cut nitrification-anaerobic ammonia oxidation technology.However, there is still residual nitrate nitrogen in the effluent of short-cut nitrification-anaerobic ammonia oxidation process, which is due to the production of nitrate nitrogen by-product in the process of anaerobic ammonia oxidation, accounting for 11% of the amount of ammonia nitrogen removed, so only through short-cut nitrification-anaerobic ammonia oxidation process cannot meet the total nitrogen discharge standard (70mg / L) and industry drainage standard (generally 40mg / L). UTILITY MODEL CONTENT

[0005] The utility model aims at providing a kind of treatment system of high ammonia nitrogen low carbon nitrogen ratio wastewater, can guarantee that high ammonia nitrogen low carbon nitrogen ratio wastewater treatment reaches the standard of being discharged into pipe.

[0006] To achieve the above object, the utility model provides the following technical scheme:

[0007] The utility model provides a kind of treatment system of high ammonia nitrogen low carbon nitrogen ratio wastewater, including aeration sedimentation tank group, primary denitrification reactor, water tank, secondary denitrification reactor and nitrification tank that are sequentially arranged along wastewater treatment direction.

[0008] The aeration sedimentation tank group is used for removing organic matters, suspended solids, reducing metal ion concentration and adjusting pH value of sewage;

[0009] The primary denitrification reactor is in communication with the aeration sedimentation tank group, and is used for carrying out short-cut nitrification reaction and anaerobic ammonia oxidation reaction;

[0010] The top of the water tank is in communication with the primary denitrification reactor, and the bottom of the water tank is in communication with the secondary denitrification reactor through a first pipeline, and the first pipeline is also used for being in communication with a carbon source;

[0011] The secondary denitrification reactor is used for carrying out denitrification reaction coupled with short-cut denitrification reaction and anaerobic ammonia oxidation reaction, and has a first water outlet in communication with the first pipeline and a second water outlet in communication with the nitrification tank, which is used for oxidizing ammonia nitrogen in wastewater into nitrate nitrogen.

[0012] Further, the aeration sedimentation tank group comprises a pre-aeration tank and a sedimentation tank;

[0013] The pre-aeration tank has an acid / alkali liquid feeding port, and the bottom of the pre-aeration tank is provided with a first aeration device;

[0014] Further, the primary denitrification reactor comprises a tank body, a stirrer, a second aeration device, a first filler assembly and a first settler, the second aeration device is installed at the bottom of the tank body, the first filler assembly is installed in the tank body and above the second aeration device, the stirrer extends into the tank body, and the first settler is installed at the outlet of the tank body.

[0015] Further, the first filler assembly comprises a filler frame and a plurality of filler units placed in the filler frame, the filler frame is supported on the bottom of the tank body by a support, and the plurality of filler units are arranged in layers one above another in a direction from the bottom to the top of the tank body;

[0016] In the two layers of adjacent filler units, the bottom of the upper filler unit is clamped to the top of the lower filler unit;

[0017] Each layer of the filler units comprises a plurality of rows and columns of filler units, and the adjacent filler units are tightly arranged.

[0018] Further, the filler unit comprises an outer frame, a filler body and a plurality of blocking supports;

[0019] The top end of the outer frame surrounds a limiting cavity, and the limiting cavity is used for the bottom of the outer frame of the upper filler unit to extend into;

[0020] A plurality of said baffle frames are installed in said outer frame in parallel and at intervals, and divide the space in said outer frame into a plurality of water passing cavities and a plurality of accommodating cavities distributed horizontally, and each of said accommodating cavities is provided with said filler body.

[0021] Further, an adjusting assembly is connected between each of said baffle frames and said outer frame, and said adjusting assembly is used to adjust the distance between adjacent said baffle frames.

[0022] Further, said primary denitrification reactor is also provided with an acid / alkali liquid feeding port, and / or a nutrient element feeding port.

[0023] Further, the bottom of said water tank is conical.

[0024] Further, said treatment system also comprises a water outlet tank in communication with the water outlet of said nitrification tank, said water outlet tank is provided with a third water outlet and a fourth water outlet, said third water outlet is used to communicate with a pipe network, and said fourth water outlet is in communication with the top of said water tank.

[0025] Further, along the direction of wastewater treatment, an adjusting tank is arranged upstream of said aeration sedimentation tank group.

[0026] The treatment system for high-ammonia-nitrogen and low-carbon-nitrogen-ratio wastewater provided by the utility model can produce the following advantages

[0027] Advantages:

[0028] Compared with the prior art, the treatment system for high-ammonia-nitrogen and low-carbon-nitrogen-ratio wastewater provided by the utility model adopts the treatment process of aeration sedimentation-primary denitrification-secondary denitrification-nitrification, and the bottom of the water tank can also collect anaerobic ammonia-oxidizing bacteria brought out of the primary denitrification reactor with the effluent and enter the secondary denitrification reactor with the influent from the first pipeline, so that the anaerobic ammonia-oxidizing bacteria resources can be fully utilized, and the wastewater in the secondary denitrification reactor can also return to the first pipeline, so that the high-ammonia-nitrogen and low-carbon-nitrogen-ratio wastewater treatment can reach the pipe network standard. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the specific embodiments of the utility model or the technical solutions in the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiments or the prior art description, and obviously, the drawings in the following description are some embodiments of the utility model, and those skilled in the art can also obtain other drawings according to these drawings without creating labor.

[0030] Figure 1 It is a structure schematic view of the treatment system for high-ammonia-nitrogen and low-carbon-nitrogen-ratio wastewater provided by the utility model embodiment;

[0031] Figure 2 A structure schematic view of the primary denitrification reactor is provided for the embodiment of the present application.

[0032] Figure 3 A front view of the first filler assembly (without filler frame) is provided for the embodiment of the present application.

[0033] Figure 4 A side view of the first filler assembly (without filler frame) is provided for the embodiment of the present application.

[0034] Figure 5 A side view of the filler unit is provided for the embodiment of the present application.

[0035] Icon: 1 - aeration sedimentation tank group; 11 - pre-aeration tank; 111 - first aeration device; 12 - sedimentation tank; 2 - primary denitrification reactor; 21 - tank body; 22 - agitator; 221 - blade; 23 - second aeration device; 24 - filler unit; 241 - outer frame; 2411 - annular surrounding edge; 2412 - outer frame body; 2413 - support frame; 242 - filler body; 243 - blocking frame; 244 - water passing cavity; 245 - containing cavity; 246 - sleeve; 247 - fastener; 25 - first precipitator; 26 - support; 27 - filler frame; 3 - water tank; 4 - secondary denitrification reactor; 5 - nitrification tank; 6 - first pipeline; 7 - water outlet tank; 8 - adjusting tank. DETAILED DESCRIPTION

[0036] The technical solutions of the present application will be described clearly and completely below with reference to the drawings. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0037] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0038] In the description of the utility model, it is necessary to explain, unless another explicit provision and limitation, term "installation", "link", "connection" should do broad sense understanding, for example, can be fixed connection, also can be detachable connection, or integrally connected;Can be mechanical connection, also can be electrical connection;Can be directly connected, also can be indirectly connected through intermediate medium, can be two elements inside the communication.For ordinary skilled in the art, the above terms can be understood according to the specific meaning in the utility model.

[0039] The specific embodiments of the utility model are described in detail below in conjunction with the drawings.It should be understood that the specific embodiments described herein are only used to illustrate and explain the utility model, and are not used to limit the utility model.

[0040] The embodiment is to provide a kind of high ammonia nitrogen low carbon nitrogen ratio wastewater treatment system, as shown in Figure Figure 1 It includes aeration sedimentation tank group 1, primary denitrification reactor 2, water tank 3, secondary denitrification reactor 4 and nitrification tank 5 arranged in sequence along the direction of wastewater treatment;

[0041] Aeration sedimentation tank group 1 is used to remove organic matter, suspended solids, reduce metal ion concentration and adjust the pH value of wastewater;

[0042] Primary denitrification reactor 2 is communicated with aeration sedimentation tank group 1, and primary denitrification reactor 2 is used for short nitrification reaction and anaerobic ammonia oxidation reaction;

[0043] The top of water tank 3 is communicated with primary denitrification reactor 2, and the bottom of water tank 3 is communicated with secondary denitrification reactor 4 through first pipeline 6, and first pipeline 6 is also used to communicate with carbon source;

[0044] Secondary denitrification reactor 4 is used for denitrification reaction coupled with short denitrification reaction and anaerobic ammonia oxidation reaction, and secondary denitrification reactor 4 has first water outlet communicated with first pipeline 6 and second water outlet communicated with nitrification tank 5, and nitrification tank 5 is used for oxidizing ammonia nitrogen in wastewater into nitrate nitrogen.

[0045] As shown in Figure 1The high-ammonia-nitrogen and low-carbon-nitrogen-ratio wastewater treatment system provided by the utility model has the advantages that when in use, wastewater first enters the aeration sedimentation tank group 1, the aeration sedimentation tank group 1 can remove organic matter and suspended solids in the wastewater, reduce the metal ion concentration and adjust the pH value of the wastewater, and reduce the influence on the reactions in the primary denitrification reactor 2; then the wastewater enters the primary denitrification reactor 2, short-cut nitrification and anaerobic ammonia oxidation are carried out in the reactor; then the wastewater discharged from the primary denitrification reactor 2 enters the water tank 3 from the top of the water tank, the bottom of the water tank 3 is communicated with the secondary denitrification reactor 4, the anaerobic ammonia oxidation bacteria carried out by the primary denitrification reactor 2 can be collected and enter the secondary denitrification reactor 4 from the first pipeline 6, meanwhile, the first pipeline 6 adds carbon sources into the wastewater, denitrification reaction, short-cut denitrification reaction and anaerobic ammonia oxidation are carried out in the secondary denitrification reactor 4, since the ammonia-nitrogen concentration in the effluent of the primary denitrification reactor 2 is usually 50-150 mg / L, and the effluent also contains nitrate nitrogen, the secondary denitrification reactor 4 can further remove ammonia-nitrogen and nitrate nitrogen in the water; finally, the wastewater discharged from the secondary denitrification reactor 4 enters the nitrification tank 5, after secondary denitrification, the main component of nitrogen in the wastewater is ammonia-nitrogen, the nitrification tank 5 can oxidize the ammonia-nitrogen in the wastewater into nitrate nitrogen, and in the above process, the wastewater in the secondary denitrification reactor 4 can also return to the first pipeline 6 and enter the secondary denitrification reactor 4 again to carry out short-cut denitrification reaction and anaerobic ammonia oxidation.

[0046] In the above process, it needs to be more specifically described that the primary denitrification reactor 2 mainly carries out short-cut nitrification and anaerobic ammonia oxidation to remove ammonia-nitrogen in the wastewater, and also has a certain removal of organic matter (COD), the reactor can be inoculated with ammonia-oxidizing bacteria (AOB) or enriched with anaerobic ammonium oxidation (Anammox) bacteria, or directly inoculated with seed sludge or biofilm filler similar to the seed sludge of an already operated project.

[0047] In addition, the secondary denitrification reactor 4 can be inoculated with denitrification granular sludge, mainly to complete denitrification to remove nitrite nitrogen and nitrate nitrogen, in addition, part of the anaerobic ammonia oxidation bacteria intercepted by the water tank 3 will enter the secondary denitrification reactor 4, or a small amount of anaerobic ammonia oxidation granular sludge is inoculated in the reactor to enrich, short-cut denitrification and anaerobic ammonia oxidation will occur, and ammonia-nitrogen and nitrate nitrogen in the incoming water can be removed, so the secondary denitrification reactor 4 will have the coupling of the two denitrification processes.

[0048] It should be further noted that the wastewater treatment system for high-ammonia-nitrogen and low-carbon-nitrogen-ratio wastewater is suitable for wastewater with ammonia-nitrogen concentration of 300-3000 mg / L, C / N < 1, especially C / N < 0.5, and the lower the COD (Chemical Oxygen Demand) concentration, the better, and the influent water temperature needs to be 25-38 ℃, and when the temperature is too low or too high, heat exchange equipment needs to be added, such as silane tower wastewater in the photovoltaic industry, high-ammonia-nitrogen wastewater in coal chemical industry, and ordinary sludge anaerobic digestion dewatering filtrate.

[0049] The wastewater treatment system for high-ammonia-nitrogen and low-carbon-nitrogen-ratio wastewater provided by the above embodiment has the following advantages:

[0050] 1. The wastewater treatment system for high-ammonia-nitrogen and low-carbon-nitrogen-ratio wastewater retains different functional bacteria in different reactors, and each species of bacteria can exert its maximum function. Compared with the traditional AO (Anaerobic Oxic) process, the design load is high, and the corresponding pool body is reduced, and at the same time, autotrophic bacteria can maintain a high concentration in the system and are not easy to be eliminated.

[0051] 2. The wastewater treatment system for high-ammonia-nitrogen and low-carbon-nitrogen-ratio wastewater is provided with a secondary denitrification reactor 4 and a nitrification tank 5. The anaerobic ammonia oxidation reaction occurring in the primary denitrification reactor 2 can effectively reduce the operating cost in treating high-ammonia-nitrogen and low-carbon-nitrogen-ratio wastewater, but the process will produce nitrate nitrogen, and a part of ammonia nitrogen will also remain in the system. The subsequent denitrification and nitrification can better solve this problem.

[0052] 3. The water tank 3 can recover the anaerobic ammonia oxidation bacteria and further exert their functions in the secondary denitrification reactor 4, so as to realize the full utilization of anaerobic ammonia oxidation bacteria resources.

[0053] 4. The secondary denitrification reactor 4 can be inoculated with denitrification granular sludge. Compared with the traditional AO process, the volume load is high, the anaerobic condition is better, and the carbon source dosage is low. The traditional AO carbon source dosage C / N is about 5, while the carbon source dosage C / N of the reactor is 3-3.5.

[0054] In an optional embodiment, as shown in Figure 1 along the wastewater treatment direction, an adjusting tank 8 is arranged upstream of the aeration sedimentation tank group 1, and the wastewater enters the adjusting tank 8 and is lifted to the aeration sedimentation tank group 1 by a lifting pump.

[0055] The structure of the aeration sedimentation tank group 1 will be described in detail below:

[0056] In an optional embodiment, as shown in Figure 1As shown, the aeration sedimentation tank group 1 includes a pre-aeration tank 11 and a sedimentation tank 12; the pre-aeration tank 11 is provided with an acid / alkali liquid feeding port, and the bottom of the pre-aeration tank 11 is provided with a first aeration device 111; the sedimentation tank 12 is provided with a coagulant feeding port and / or a flocculant feeding port.

[0057] In the above embodiment, the first aeration device 111 can remove part of the organic matter and suspended solids in the wastewater, and reduce the influence on the short-cut nitrification reaction and the anaerobic ammonia oxidation reaction in the first denitrification reactor 2. For the case that the concentration of certain metal ions in the wastewater exceeds the standard, personnel can pour alkali such as sodium carbonate and sodium hydroxide into the pre-aeration tank 11 through the acid / alkali liquid feeding port to adjust the pH value of the wastewater, remove the excessive metal ions, control the pH value of the wastewater between 7.3-8.3, and reduce the influence on the subsequent process section.

[0058] After pre-aeration by the first aeration device 111, personnel can pour coagulant into the wastewater through the coagulant feeding port, and / or pour flocculant into the wastewater through the flocculant feeding port, to remove the suspended solids in the water, so that the suspended solids are controlled below 100 mg / L.

[0059] The coagulant includes aluminum salt, iron salt, polymeric ferric sulfate, polyaluminum chloride, etc., and the flocculant is selected from polyaluminum ferric chloride, polyacrylamide (PAM), etc.

[0060] The structure of the first denitrification reactor 2 will be described in detail as follows:

[0061] In an optional embodiment, as shown in Figure 2 The first denitrification reactor 2 includes a tank body 21, a stirrer 22, a second aeration device 23, a first filler assembly, and a first settler 25; the second aeration device 23 is installed at the bottom of the tank body 21, the first filler assembly is installed in the tank body 21 and above the second aeration device 23, the stirrer 22 extends into the tank body 21, and the first settler 25 is installed at the outlet of the tank body 21.

[0062] Since the anaerobic ammonia oxidation bacteria inoculated in the first denitrification reactor 2 is granular sludge, it is difficult to achieve good mixing effect only by the second aeration device 23, especially at the initial stage of biofilm formation or when the system cannot be aerated due to high nitrite concentration, the stirrer 22 can achieve good stirring effect.

[0063] In addition, the addition of the first filler assembly in the first denitrification reactor 2 not only provides a better anaerobic environment for the anaerobic ammonia oxidation bacteria, but also is beneficial to the uniform distribution of sludge in the tank body 21, reducing the operating pressure of the inlaid sedimentation tank.

[0064] The first filler assembly can adopt a hydrophilic filler such as a sponge filler, which is beneficial to the adhesion and growth of the anammox bacteria, prevents the loss of the bacteria in the initial start-up period, is beneficial to the proliferation of the anammox bacteria, forms a biofilm, and provides micro-aerobic and anaerobic conditions.

[0065] Specifically, the reaction formula of the short-cut nitrification is as follows:

[0066] NH + 4+1.5O2→NO - 2+2H + +H2O;

[0067] The reaction formula of the anammox is as follows:

[0068] NH + 4+1.32NO - 2+0.066HCO - 3+0.12H + →1.0N2↑+0.26NO - 3+0.066C

[0069] H2O 0.5 N 0.15 +2.03H2O.

[0070] The above two reactions occur in the first-stage denitrification reactor 2, and the two types of bacteria are autotrophic bacteria with a long doubling time, and in particular, the doubling time of the anammox bacteria is as long as 11 days. As can be seen from the above reactions, aeration is required in the short-cut nitrification stage, and alkalinity is required to neutralize the acid produced by the reaction, the anammox bacteria are anaerobic bacteria and require an anaerobic environment to function, and the reactor has a high requirement for dissolved oxygen, so the pH and DO (Dissolved Oxygen) parameters need to be controlled in the reactor, the anaerobic environment for the anammox bacteria is created by the biological membrane and the particles, and based on the analysis of the influent water quality, the necessary nutrient elements for the growth of the anammox bacteria, such as Fe(II), Ni(II), Zn(II), Cu(II), Mn(II) and Co(II), are indispensable trace elements in the growth and metabolism process of the anammox microorganisms, and the compounds containing P, K, Na, Mg and the like required for the growth of the microorganisms are supplemented.

[0071] Therefore, in the optional implementation, the first-stage denitrification reactor 2 further has a nutrient element feeding port.

[0072] As can be seen from the above reaction formula, the reaction produces a small amount of nitrate nitrogen when removing ammonia nitrogen, accounting for about 11% of the concentration of removed ammonia nitrogen. In order to ensure that nitrification is stopped in the short nitrification section and prevent the proliferation of two-step nitrification bacteria, i.e., ammonia nitrogen is converted into nitrate nitrogen, which cannot provide nitrite nitrogen substrate for anaerobic ammonia oxidation bacteria, the reactor maintains a certain concentration of ammonia nitrogen, which is usually not less than 50 mg / L. Therefore, after the high ammonia nitrogen wastewater passes through the first denitrification reactor, the ammonia nitrogen concentration in the effluent is 50-150 mg / L, and the effluent also contains nitrate nitrogen. The second denitrification reactor 4 can remove the nitrate nitrogen produced by the first denitrification reactor 2, a small amount of ammonia nitrogen, and the nitrate nitrogen brought by nitrification reflux. The nitrification tank 5 can remove ammonia nitrogen, so that the ammonia nitrogen concentration is less than 25 mg / L, and the total nitrogen is less than 70 mg / L, meeting the pipe standard.

[0073] Specifically, based on the nutrient solution required for the anaerobic ammonia oxidation bacteria in the pool body 21, the reactor needs to control the DO to be 0-0.5 mg / L. The first denitrification reactor 2 also has an acid / alkali liquid pouring port to control the pH to be between 7.2-8.3, and the ammonia nitrogen concentration is controlled to be 50-150 mg / L, the nitrite nitrogen concentration is controlled to be less than 10 mg / L, and the detection of the ratio of nitrate nitrogen generation / ammonia nitrogen degradation is less than 0.15.

[0074] In an optional embodiment, as shown in Figure 2 The first filler assembly includes a filler frame 27 and a plurality of filler units 24 placed in the filler frame 27. The filler frame 27 is supported on the bottom of the pool body 21 by a support 26. During processing, each filler unit 24 can be processed separately, which facilitates the preparation of the first filler assembly.

[0075] The above-mentioned filler frame 27 can be one or multiple, and the number thereof can be selected according to the height of the pool body 21. When the filler frame 27 is multiple, the multiple filler frames 27 are stacked from bottom to top.

[0076] The arrangement of the multiple filler units 24 can be various. In an optional embodiment, in order to facilitate the stable placement of each filler unit 24 in the filler frame 27, as shown in Figures 2 to 4 The multiple filler units 24 are arranged layer by layer in the direction from the bottom to the top of the pool body 21. The bottom of the upper filler unit 24 in the adjacent two layers of filler units 24 is clamped to the top of the lower filler unit 24. Each layer of filler units 24 includes multiple rows and multiple columns of filler units 24, and the adjacent filler units 24 are tightly arranged.

[0077] In the above embodiments, the bottom of the upper filler unit 24 is clamped to the top of the lower filler unit 24, and the lower filler unit 24 can limit the upper filler unit 24, without the need for additional connection components such as a cable tie to fix the upper and lower adjacent filler units 24, facilitating the assembly of the filler units 24. In addition, the adjacent filler units 24 in each layer of filler units 24 are closely arranged and assist in supporting each other, and the adjacent filler units 24 can also be connected by a cable tie, so that the plurality of filler units 24 form a whole and are stably placed in the pool body 21.

[0078] On the basis of the above various embodiments, as shown in Figure 5 The filler unit 24 comprises an outer frame 241, a filler body 242, and a plurality of blocking frames 243, wherein:

[0079] The top end of the outer frame 241 is provided with an annular surrounding edge 2411, and the annular surrounding edge 2411 surrounds a limiting cavity. In assembly, the bottom of the outer frame 241 in the upper filler unit 24 can be clamped into the limiting cavity to limit the horizontal position of the upper filler unit 24.

[0080] The plurality of blocking frames 243 are installed in parallel and at intervals in the outer frame 241, and divide the space in the outer frame 241 into a plurality of horizontally distributed water passing cavities 244 and a plurality of accommodating cavities 245. Each accommodating cavity 245 is provided with a filler body 242, and the filler body 242 can be tied to the outer frame 241.

[0081] In the above embodiments, the accommodating cavity 245 can limit the position of the filler body 242. The purpose of the water passing cavity 244 is to form a water passing gap between the filler bodies 242 to increase the contact area between the filler bodies 242 and the sewage, as the filler bodies 242 are densely stacked and the second aeration device 23 is arranged below the first filler assembly.

[0082] Specifically, as shown in Figure 4 The water passing cavity 244 and the accommodating cavity 245 can be alternately distributed, that is, one water passing cavity 244 is clamped between two accommodating cavities 245, so that the two sides of the filler body 242 in the accommodating cavity 245 can be fully contacted with the sewage, avoiding the concentrated stacking of the filler, and improving the utilization rate of the filler.

[0083] In addition, the two filler bodies 242 close to each other between the two horizontally adjacent filler units 24 are also separated by the water passing cavity 244, so that a gap for water passing is formed between the two horizontally adjacent filler units 24.

[0084] In an optional embodiment, the outer frame 241 comprises an outer frame body 2412 and a support frame 2413 connected to the inner frame body 2412, the support frame 2413 is horizontally arranged, the top end of the blocking frame 243 is connected to the outer frame body 2412, the bottom end of the blocking frame 243 is connected to the support frame 2413, and a water passing cavity 244 is also formed between the lower part of the support frame 2413 and the outer frame body 2412, so that the adjacent two filler bodies 242 have a water passing gap, thereby increasing the contact area between the filler body 242 and the sewage.

[0085] In an optional embodiment, an adjusting assembly is connected between each blocking frame 243 and the outer frame 241, the adjusting assembly is used to adjust the distance between the adjacent blocking frames 243, so as to adjust the width of the containing cavity 245, and adapt to filler bodies 242 of different sizes.

[0086] Specifically, the adjusting assembly can comprise sleeves 246 arranged at the upper and lower ends of the blocking frame 243; the sleeve 246 at the lower end is sleeved outside the crossbeam of the support frame 2413 and can slide relative to the crossbeam; the sleeve 246 at the upper end is sleeved outside the crossbeam of the outer frame body 2412 and can slide relative to the crossbeam; a fastener 247 is arranged between each sleeve 246 and the crossbeam, the fastener 247 is threadedly connected with the sleeve 246, when the fastener 247 is loosened, the sleeve 246 can slide relative to the crossbeam, when the fastener 247 is tightened, the fastener 247 can lock the position of the sleeve 246 relative to the crossbeam, and the fastener 247 can be a screw.

[0087] In addition, the agitator 22 can comprise a motor, a rotating shaft and a blade 221, the motor is fixedly arranged at the top of the pool body 21, one end of the rotating shaft is connected with the power output shaft of the motor, and the other end extends into the pool body 21 and is connected with the blade 221, the rotating shaft can drive the blade 221 to rotate under the drive of the motor.

[0088] It should be noted that, in order to avoid that the agitator 22 generates a large shear force on the sewage during rotation, the rotating speed of the agitator 22 needs to be set relatively low.

[0089] Preferably, the agitator 22 adopts a double-curved-surface agitator.

[0090] The structure of the water tank 3 will be described below:

[0091] In an optional embodiment, as shown in Figure 1 the bottom of the water tank 3 is conical.

[0092] The conical tank bottom can collect the anammox bacteria brought out of the first-stage denitrification reactor 2 with the effluent and enter the second-stage denitrification reactor 4 with the influent, thereby realizing full utilization of the anammox bacteria resources.

[0093] The structure of the nitrification tank 5 will be described below:

[0094] In an optional embodiment, the nitrification tank 5 is provided with a second filler assembly, a third aeration device and a second settler, the third aeration device is installed at the bottom of the tank, the second filler assembly is installed in the tank and above the third aeration device, and the second settler is installed at the outlet of the tank.

[0095] The nitrification tank 5 is similar to the first denitrification reactor 2, and both are provided with a settler, so that sludge backflow can be omitted, the energy consumption of the sludge backflow pump is reduced, the particle morphology in the sludge is protected from being damaged by the backflow pump, and the sludge has good sedimentation.

[0096] The structure of the second filler assembly can be similar to that of the first filler assembly, and will not be described in detail here for the sake of brevity.

[0097] In an optional embodiment, the treatment system further comprises a water outlet tank 7 communicating with the water outlet of the nitrification tank 5, the water outlet tank 7 has a third water outlet and a fourth water outlet, the third water outlet is used to communicate with a pipe network, and the fourth water outlet communicates with the top of the water tank 3.

[0098] When the total nitrogen of the water outlet of the water outlet tank 7 is higher than the pipe connection standard, the water outlet can be backflowed to the water tank 3 through the fourth water outlet, mixed with the water outlet of the first denitrification reactor 2, and then enters the second denitrification reactor 4 to remove nitrate nitrogen, so as to ensure that the total nitrogen of the water outlet meets the discharge standard.

[0099] The following describes the use method of the treatment system for high-ammonia-nitrogen and low-carbon-nitrogen-ratio wastewater in a specific embodiment:

[0100] The water used in the pilot experiment is taken from the dewatering filtrate after anaerobic digestion of sludge in a sludge plant, and the sludge is not pretreated before anaerobic digestion. The water quality of the dewatering filtrate (biogas liquid) is as follows:

[0101] CODcr is 300-700 mg·L －1 , NH + 4-N is 500-1000 mg·L －1 , the total nitrogen content is 500-1000 mg·L －1 , the total phosphorus content is less than 1 mg·L －1 , the suspended solids content is 300-800 mg·L －1 , and the pH is 6-7.

[0102] The design of the pilot experimental device is 1-2 m 3 / day, and the treatment capacity is 1 kg N / d. The process flow is referred to the above embodiment. The biogas slurry is first lifted by a pump and then enters the pre-aeration tank 11. The aeration time is about 2 h. During this period, NaOH is added to adjust the pH to about 8. After the aeration, the biogas slurry enters the coagulation and sedimentation tank, and polyaluminum chloride solution is added. The content of the polyaluminum chloride is about 10%, and the dosage is 200-500 ml per ton of water. After the sedimentation, the suspended solids content of the effluent is 30-100 mg·L －1 , the COD is reduced from 500 mg·L －1 to about 400 mg·L －1 , and then enters the first denitrification reactor 2.

[0103] The first denitrification reactor 2 is directly inoculated with AOB bacteria and Anammox granular bacteria. The filler is hydrophilic sponge filler. The start-up is completed by controlling DO, pH and nitrite nitrogen concentration. The Anammox bacteria adhere to and grow on the filler. The outer edge of the biofilm is AOB bacteria, which improves the anaerobic environment for the Anammox bacteria in the biofilm. In addition, there are suspended sludge and granular sludge in the reactor. The three coexist in the first denitrification reactor 2, so that the AOB bacteria and the Anammox bacteria can play various roles in the aeration environment to complete the removal of ammonia nitrogen. In the early stage of start-up, the reactor is inoculated with flocculent sludge containing anaerobic ammonia oxidation bacteria. However, NOB bacteria proliferation occurs during operation, which is difficult to recover. Only re-start-up can be performed. Through a small-scale experiment of the short-cut nitrification-anaerobic ammonia oxidation process, a system in which biofilm, granular sludge and suspended sludge coexist is finally selected. At present, the process has been operated for 2 years, and NOB proliferation phenomenon has not occurred. The DO in the reactor is maintained at 0-0.5 mg·L －1 by adjusting the aeration amount. The pH in the reactor is controlled at about 7.5-8 by adding sodium carbonate solution. The water temperature is controlled at 25-35℃. The nitrite nitrogen concentration is maintained at 10 mg·L －1 . The effluent ammonia nitrogen is controlled at 50-150 mg·L －1 . The nitrate nitrogen concentration is 40-80 mg·L －1 . The COD is 200-300 mg·L －1 . In addition, since a large amount of iron salt is added during the plate and frame dehydration of the sludge after anaerobic digestion, the phosphorus content in the wastewater is reduced. Therefore, potassium dihydrogen phosphate solution needs to be added to supplement the phosphorus required for the growth of microorganisms. The phosphorus concentration in the first denitrification reactor is controlled at 2-5 mg·L －1 . An embedded sedimentation tank is arranged in the reactor, and the effluent enters the water tank 3.

[0104] The water tank 3 is arranged as a vertical flow sedimentation tank structure, suspended solids in the effluent of the first-stage denitrification reactor 2 continue to be separated in the water tank 3, and the suspended solids contain part of the anammox bacteria, at the initial stage of the process start-up, the settled sludge is returned to the first-stage denitrification reactor 2, and after the start-up is completed, the sludge enters the second-stage denitrification reactor 4 with the wastewater. At the initial stage of the experiment, the reactor is inoculated with anammox granular sludge, and the short-cut denitrification anammox process can be directly started by selecting sodium acetate as the carbon source, the effluent is added with the carbon source at a C / N ratio of about 2, the removal of ammonia nitrogen and nitrate nitrogen can be realized, the total nitrogen in the effluent is below 70 mg / L, but after the carbon source is replaced by the composite carbon source, the contribution rate of the short-cut denitrification-anammox denitrification reaction in the total nitrogen removal gradually decreases. Therefore, the second-stage denitrification is inoculated with the denitrification granular sludge cultured in the laboratory, and the start-up is directly completed, and most of the nitrate nitrogen in the influent can be removed by adding the composite carbon source at a C / N ratio of 3-3.5, the nitrate nitrogen in the effluent is about 10 mg / L, the ammonia nitrogen in the effluent is also reduced compared with the ammonia nitrogen in the effluent of the first-stage denitrification reactor, and is about 10%-20%, which indicates that the short-cut denitrification-anammox reaction also occurs. Therefore, considering the economy and operation stability, the second-stage denitrification reactor 4 selects the denitrification process mainly based on denitrification, and simultaneously supplemented by the short-cut denitrification-anammox reaction, which is also the secondary use of the anammox bacteria in the effluent of the first-stage denitrification reactor 2. The second-stage denitrification reactor 4 selects the UASB (Up-flow Anaerobic Sludge Bed / Blanket) structure, which has a good interception effect on the denitrification granular sludge, and the volume load is more than 5 times of that of the traditional AO process. The effluent of the second-stage reactor has ammonia nitrogen of 30-50 mg·L －1 , nitrate nitrogen of 0-15 mg·L －1 , nitrite nitrogen of 0-5 mg / L, and COD of about 300 mg·L －1 , and the effluent enters the nitrification tank 5.

[0105] The nitrification tank 5 mainly oxidizes the ammonia nitrogen in the effluent of the second-stage denitrification reactor 4 to nitrate nitrogen, and the bacteria mainly causing the reaction are AOB and NOB, which are autotrophic bacteria and have a long doubling time. Since the denitrification sludge of the second-stage denitrification reactor 4 is intercepted in the second-stage denitrification reactor 4 by the three-phase separator, the sludge discharge of the nitrification tank 5 is reduced, the sludge age is long, the number of nitrifying bacteria in the sludge is much higher than that in the traditional AO system, the sludge load is high, the tank capacity is small, and the land occupation is small. Based on the ammonia nitrogen concentration in the effluent of the first-stage denitrification reactor 2 of the denitrification system, the proportion of the nitrification tank effluent returned to the intermediate water tank is adjusted to ensure that the ammonia nitrogen in the nitrification tank effluent is controlled to be below 15 mg·L －1 , the total nitrogen concentration is below 60 mg·L －1 , and the COD is below 500 mg·L －1 .

[0106] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not limited thereto; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can still be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A treatment system for wastewater with high ammonia nitrogen and low carbon-to-nitrogen ratio, characterized in that, It includes an aeration sedimentation tank group (1), a primary denitrification reactor (2), a water tank (3), a secondary denitrification reactor (4), and a nitrification tank (5) arranged sequentially along the wastewater treatment direction; The aeration sedimentation tank group (1) is used to remove organic matter and suspended solids from sewage, reduce the concentration of metal ions, and adjust the pH value of sewage. The primary denitrification reactor (2) is connected to the aeration sedimentation tank group (1), and the primary denitrification reactor (2) is used for short-cut nitrification and anaerobic ammonia oxidation. The top of the water tank (3) is connected to the primary denitrification reactor (2), and the bottom of the water tank (3) is connected to the secondary denitrification reactor (4) through the first pipe (6). The first pipe (6) is also used to connect to the carbon source. The secondary denitrification reactor (4) is used to perform denitrification reaction coupled with short-cut denitrification reaction and anaerobic ammonia oxidation reaction. The secondary denitrification reactor (4) has a first outlet connected to the first pipeline (6) and a second outlet connected to the nitrification tank (5). The nitrification tank (5) is used to oxidize ammonia nitrogen in wastewater into nitrate nitrogen.

2. The wastewater treatment system for high ammonia nitrogen and low carbon-to-nitrogen ratio according to claim 1, characterized in that, The aeration sedimentation tank group (1) includes a pre-aeration tank (11) and a sedimentation tank (12); The pre-aeration tank (11) has an acid / alkali liquid inlet, and the bottom of the pre-aeration tank (11) is provided with a first aeration device (111). The sedimentation tank (12) has a coagulant inlet and / or a flocculant inlet.

3. The wastewater treatment system for high ammonia nitrogen and low carbon-to-nitrogen ratio according to claim 1, characterized in that, The primary denitrification reactor (2) includes a tank body (21), a stirrer (22), a second aeration device (23), a first packing assembly, and a first sedimentation tank (25). The second aeration device (23) is installed at the bottom of the tank body (21), the first packing assembly is installed inside the tank body (21) and above the second aeration device (23), the stirrer (22) extends into the tank body (21), and the first sedimentation tank (25) is installed at the outlet of the tank body (21).

4. The wastewater treatment system for high ammonia nitrogen and low carbon-to-nitrogen ratio according to claim 3, characterized in that, The first packing assembly includes a packing frame (27) and a plurality of packing units (24) placed inside the packing frame (27). The packing frame (27) is supported at the bottom of the pool body (21) by a bracket (26). The plurality of packing units (24) are stacked layer by layer inside the packing frame in the direction from the bottom of the pool body (21) to the top. In two adjacent layers of packing units (24), the bottom of the upper packing unit (24) is snapped into the top of the lower packing unit (24); Each layer of the packing unit (24) includes multiple rows and columns of the packing units (24), and adjacent packing units (24) are arranged in close contact.

5. The wastewater treatment system for high ammonia nitrogen and low carbon-to-nitrogen ratio according to claim 4, characterized in that, The packing unit (24) includes an outer frame (241), a packing body (242), and multiple baffles (243); The top of the outer frame (241) is surrounded by a limiting cavity, which is used for the bottom of the outer frame (241) of the upper filling unit (24) to extend into. Multiple baffles (243) are installed parallel to each other and spaced apart inside the outer frame (241), dividing the space inside the outer frame (241) into multiple horizontally distributed water passage chambers (244) and multiple receiving chambers (245), and each of the receiving chambers (245) is provided with the packing body (242).

6. The wastewater treatment system for high ammonia nitrogen and low carbon-to-nitrogen ratio according to claim 5, characterized in that, Each of the baffles (243) is connected to the outer frame (241) by an adjustment component, which is used to adjust the distance between adjacent baffles (243).

7. The wastewater treatment system for high ammonia nitrogen and low carbon-to-nitrogen ratio according to claim 1, characterized in that, The primary denitrification reactor (2) also has an acid / alkali inlet and / or a nutrient inlet.

8. The wastewater treatment system for high ammonia nitrogen and low carbon-to-nitrogen ratio according to any one of claims 1-7, characterized in that, The bottom of the water tank (3) is conical.

9. The wastewater treatment system for high ammonia nitrogen and low carbon-to-nitrogen ratio according to any one of claims 1-7, characterized in that, The treatment system also includes an outlet pool (7) connected to the outlet of the nitrification tank (5). The outlet pool (7) has a third outlet and a fourth outlet. The third outlet is used to connect to the pipeline network, and the fourth outlet is connected to the top of the water tank (3).

10. The treatment system for high ammonia nitrogen and low carbon-to-nitrogen ratio wastewater according to any one of claims 1-7, characterized in that, Along the wastewater treatment direction, an equalization tank (8) is provided upstream of the aeration sedimentation tank group (1).

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