A water treatment method based on granular sludge coupled with flocculent sludge by biofilm method

Abstract

The present invention relates to the field of water treatment, and discloses a water treatment method based on granular sludge coupled with flocculent sludge by biofilm method, which includes: (1) Cultivation stage: Anaerobic ammonium oxidation granular sludge and nitrification / denitrification flocculent sludge are introduced into the reactor, wastewater is introduced, and the circulating return water is mixed with the wastewater and then passes through the bottom sludge bed, granular sludge reaction zone, biofilm reaction zone and three-phase separator in sequence under aeration. Part of it flows out from the three-phase separator, and the remaining part is used as circulating return water; The cultivation stage is sequentially divided into: Bacterial screening stage, adopting intermittent aeration and intermittent water inlet mode; Activity change stage, continuous aeration and water inlet mode are adopted in the activity improvement stage and the activity stabilization stage; (2) Stabilization stage: The same as the activity stabilization stage. The method of the present invention can improve the granularity of anaerobic ammonium oxidation granular sludge, reduce the amount of sludge running away, and maintain the activity for a long time; It can significantly shorten the start-up time of the traditional anaerobic ammonium oxidation process and improve the average total nitrogen removal efficiency.

Description

Technical Field

[0001] The present invention relates to the field of water treatment, and particularly to a water treatment method based on granular sludge coupled with flocculent sludge by a biofilm method. Background Art

[0002] High ammonia nitrogen sewage / wastewater has a wide range of sources, including but not limited to sludge digestion liquid, kitchen waste biogas slurry, monosodium glutamate wastewater, photovoltaic wastewater, etc. High ammonia nitrogen wastewater often also has a low carbon-nitrogen ratio. When treated by traditional nitrification and denitrification processes, there are many disadvantages such as low process nitrogen load, large required reaction tank volume, high demand for carbon sources, and high aeration energy consumption, which make the construction investment and operation treatment cost of high ammonia nitrogen sewage / wastewater remain high.

[0003] In view of the disadvantages of traditional processes, the anaerobic ammonium oxidation process has greatly reduced the sewage / wastewater treatment cost with its special nitrogen removal path. However, at the same time, the anaerobic ammonium oxidation process also has certain difficulties in application and promotion, that is, the growth and reproduction doubling time of anaerobic ammonium oxidation microorganisms is relatively long, resulting in the scarcity of seed sludge during the market promotion process.

[0004] At present, the main anaerobic ammonium oxidation processes are divided into two forms based on granular sludge and based on biofilm. Among them, the anaerobic ammonium oxidation process based on granular sludge has the advantages of high sludge concentration and high nitrogen load (up to 1.4 - 2.0 N kg / (m 3 *d)), but the formation conditions of granular sludge are relatively harsh, and there are strict requirements for the types and water quality parameters of sewage / wastewater, severely limiting its application scenarios; while the anaerobic ammonium oxidation process of flocculent sludge based on biofilm has a relatively lower nitrogen load (0.7 - 1.2 N kg / (m 3 *d)) compared with the granular sludge process, and it is prone to sludge loss, resulting in poor system operation stability.

[0005] In the start-up and operation of the anaerobic ammonium oxidation process, there are two start-up methods, but each has its own disadvantages: ① Starting with granulated sludge: Due to the lack of anaerobic ammonium oxidation granular sludge resources in actual engineering applications, and some water qualities cannot be continuously granulated during commissioning and operation, the originally inoculated granular sludge will gradually disintegrate and flow out with the effluent, restricting the application and promotion of this process; ② Starting with zero sludge: That is, it is obtained by gradually enriching and domesticating anaerobic bacteria, nitrifying bacteria or denitrifying bacteria for a long time. Although the abundance of anaerobic ammonium oxidation bacteria is higher for nitrifying bacteria and denitrifying bacteria in this method, they basically exist in the form of flocculent sludge. Therefore, during the long-term enrichment and domestication process, obvious flocculent sludge loss will occur, especially in upflow reactors.

[0006] Therefore, making full use of the respective characteristics of granular sludge and flocculent sludge and constructing technologies and devices that can maintain a relatively high sludge concentration in the reactor for a long time are important ways to solve the problems in the prior art such as the difficult start-up of the anaerobic ammonium oxidation process, significant sludge loss, and limited application scenarios. Summary of the Invention

[0007] Aiming at the technical problems in the prior art such as the difficult start-up of the anaerobic ammonium oxidation process, significant sludge loss, and limited application scenarios, the present invention provides a water treatment method based on granular sludge coupled with flocculent sludge by biofilm method. The method of the present invention can improve the granularity of anaerobic ammonium oxidation granular sludge, reduce the amount of running sludge, and maintain its activity for a long time; it can significantly shorten the start-up time of the traditional anaerobic ammonium oxidation process, and the average removal efficiency of total nitrogen can reach more than 90%.

[0008] The specific technical solution of the present invention is as follows: A water treatment method based on granular sludge coupled with flocculent sludge by biofilm method, comprising the following steps:

[0009] (1) Cultivation stage: Anaerobic ammonium oxidation granular sludge and nitrification / denitrification flocculent sludge are introduced into the reactor, and wastewater is introduced. After the appearance of circulating return water, it is mixed with the wastewater to form mixed wastewater and then introduced into the reactor. Under aeration, the water flow sequentially passes through the bottom sludge bed, granular sludge reaction zone, biofilm reaction zone, and three-phase separator in the reactor. Part of it flows out from the three-phase separator, and the remaining part is used as circulating return water.

[0010] The cultivation stage is sequentially divided into: the bacterial screening stage, adopting the intermittent aeration and intermittent water inlet mode; the activity change stage, the activity improvement stage, and the activity stabilization stage adopting the continuous aeration and water inlet mode; the dissolved oxygen and the reflux ratio of the circulating return water in the latter stage are not lower than those in the previous stage.

[0011] (2) Stabilization stage: Maintain the process of the activity stabilization stage.

[0012] In the cultivation stage of the present invention, the bottom sludge is dispersed by bottom aeration and rises to the granular sludge reaction zone through a reflux pump. Ammonia nitrogen and nitrite nitrogen in the wastewater will preferentially react for denitrification in the granular sludge reaction zone, and the ammonia nitrogen and nitrite nitrogen that are not completely removed will continue to complete the remaining denitrification in the biofilm reaction zone. The flocculent sludge generated in the granular sludge zone will float to the biofilm reaction zone along with the bubbles generated in the reactor and adhere to the packing to complete the interception of part of the sludge, and at the same time create a second denitrification area. When the wastewater completes the reaction in the granular sludge reaction zone and the biofilm reaction zone, nitrogen gas directly escapes from the top of the reactor, and the wastewater enters the three-phase separator for mud-water separation. After the separation is completed, the granular sludge and part of the flocculent sludge return to the lower part of the biofilm reaction zone again, and the effluent is discharged to the effluent tank through the upper part of the three-phase separator.

[0013] Based on the coupling of granular sludge and flocculent sludge, the present invention specifically divides this stage into four sub-stages, and different aeration and influent modes are adopted in each sub-stage. This method can improve the granularity of anaerobic ammonium oxidation granular sludge, reduce the sludge loss, and maintain the sludge activity for a long time. Compared with the traditional anaerobic ammonium oxidation process, the start-up time can be significantly shortened.

[0014] Preferably, in step (1), the four sub-stages of the cultivation stage are respectively:

[0015] The 1st - 30th day is the bacterial screening stage, adopting intermittent aeration and intermittent influent modes. When aerating, the dissolved oxygen in water is controlled at 0.5 - 0.7 mg / L, and when influenting, the reflux ratio of the recycled return water is 28 - 32%; in the bacterial screening stage, the intermittent aeration is 50 - 70 minutes of aeration followed by 50 - 70 minutes of stop; the intermittent influent is that after the single influent volume reaches the reactor capacity, it stops for 1.5 - 2.5 hours.

[0016] In the bacterial screening stage, intermittent aeration and influent with low dissolved oxygen (0.5 - 0.7 mg / L) and high reflux ratio (28 - 32%) are carried out. Among them, each time influent, the dissolved oxygen value DO in the reactor is feedback - linked and controlled at 0.5 - 0.7 mg / L through real - time monitoring of the dissolved oxygen in the monitoring sensor. The reactor with a high reflux ratio can evenly distribute the dissolved oxygen and material concentration in the reactor, and provide a higher upward flow velocity to accelerate the formation of granular sludge. Influenting every 1.5 - 2.5 hours can ensure that the ammonia nitrogen concentration in the reactor is sufficient for nitrite oxidation reaction. During low - dissolved - oxygen aeration (DO < 1.5 mg / L), especially when DO < 1 mg / L, the activity of nitrite oxidation reaction is much higher than that of nitrification reaction, so that ammonia - oxidizing bacteria AOB will gradually replace nitrite - oxidizing bacteria NOB. Since intermittent aeration is adopted, the ratio of anaerobic time to aerobic time is about 1:1, which can enable the nitrate generated by nitrification reaction to be fully consumed by the denitrification reaction dominated by denitrifying bacteria, rapidly increasing the content of nitrite and thus inhibiting the activity of nitrifying bacteria. In addition, at low dissolved - oxygen concentration, anaerobic ammonium - oxidizing bacteria can also slowly proliferate due to sufficient nitrite and ammonia nitrogen. Therefore, mainly nitrite - oxidizing bacteria are screened out and anaerobic ammonium - oxidizing bacteria are retained in this stage, and nitrifying bacteria are gradually eliminated due to their inability to adapt to the environment.

[0017] The 31st - 60th day is the activity change stage, adopting continuous aeration and continuous influent modes, controlling the dissolved oxygen in water at 0.7 - 1 mg / L, and the reflux ratio of the recycled return water is 28 - 32%.

[0018] During the activity change stage, continuous aeration and influent are carried out with long-term low dissolved oxygen (0.7 - 1 mg / L) and high reflux ratio (28 - 32%). The dissolved oxygen value DO in the reactor is feedback-linked controlled within 0.7 - 1 mg / L through real-time monitoring of the dissolved oxygen in the monitoring sensor. Keeping the high reflux ratio of the reactor (28 - 32%) unchanged, continue to evenly distribute the dissolved oxygen and material concentration in the reactor, and provide a relatively high upward flow velocity to accelerate the formation of granular sludge. After screening out nitrite bacteria and anaerobic ammonium oxidation bacteria, a continuous influent mode is adopted to provide sufficient substrates for the proliferation and reaction of nitrite bacteria, and appropriately increase the dissolved oxygen DO value (0.7 - 1 mg / L, < 1.5 mg / L), so that the dominant nitrite bacteria produce more nitrite, and during this process, the proliferation of denitrifying bacteria is inhibited to prevent denitrifying bacteria from directly using the remaining carbon source in the wastewater to directly remove nitrite as nitrogen, thereby enabling anaerobic ammonium oxidation bacteria to obtain sufficient nitrite and ammonia nitrogen as substrates for proliferation and reaction.

[0019] From the 61st to the 90th day is the activity improvement stage, adopting continuous aeration and continuous influent mode, controlling the dissolved oxygen in the water to be 0.9 - 1.1 mg / L, and the reflux ratio of the recycled backflow water to be 38 - 42%.

[0020] During the activity improvement stage, continuous aeration and influent are carried out with long-term low dissolved oxygen (0.9 - 1.1 mg / L) and high reflux ratio (38 - 42%). The dissolved oxygen value DO in the reactor is feedback-linked controlled around 1 mg / L through real-time monitoring of the dissolved oxygen in the monitoring sensor 12. Increase the high reflux ratio of the reactor to (38 - 42%) to accelerate the even distribution of the dissolved oxygen and material concentration in the reactor, and start to form anaerobic ammonium oxidation granular sludge. Maintain low dissolved oxygen (0.9 - 1.1 mg / L) to accelerate the proliferation of nitrite bacteria and convert more ammonia nitrogen into nitrite to provide nitrite for anaerobic ammonium oxidation granular sludge, and form anaerobic ammonium oxidation granular sludge through the synergistic action of nitrite bacteria and anaerobic ammonium oxidation bacteria.

[0021] From the 91st to the 110th day is the activity stabilization stage, adopting continuous aeration and continuous influent mode, controlling the dissolved oxygen in the water to be 1 - 1.5 mg / L, and the reflux ratio of the recycled backflow water to be 48 - 52%.

[0022] During the active stabilization stage, continuous aeration and influent feeding are carried out with a long-term low dissolved oxygen (1 - 1.5 mg / L) and a high reflux ratio (48 - 52%). The dissolved oxygen value DO in the reactor is feedback-linked and controlled at around 1 - 1.5 mg / L through real-time monitoring of the dissolved oxygen in the monitoring sensor 12. Continuously increase the high reflux ratio of the reactor to (48 - 52%) to accelerate the uniform distribution of dissolved oxygen and material concentration in the reactor, and the increased upward flow rate can quickly consolidate the anaerobic ammonium oxidation granular sludge and accelerate the separation of granular sludge and flocculent sludge, and promote the formation of more anaerobic ammonium oxidation granular sludge, and finally, anaerobic ammonium oxidation granular sludge with a higher granularity can be obtained.

[0023] During the entire cultivation stage, if the concentration ratio of nitrite nitrogen to ammonia nitrogen > 1.5:1, immediately stop aeration and / or stop influent feeding, and restart after recovery.

[0024] During the entire cultivation stage, once the concentration of nitrite nitrogen approaches the inhibitory concentration range (nitrite: ammonia nitrogen > 1.5:1), it is necessary to immediately shut down the aeration system, correspondingly reduce the dissolved oxygen in the reactor, thereby weakening the nitrification reaction and reducing the supply of nitrite nitrogen, or stop influent feeding. After a part of the nitrite nitrogen in the reactor is gradually consumed, then restart influent feeding. During the entire cultivation stage, in the context of completing nitrification / anaerobic ammonium oxidation in the reactor, control the dissolved oxygen concentration in the reactor between 0.5 - 1.5 mg / L, while inhibiting nitrite-oxidizing bacteria NOB, ensuring the positive activity of ammonia-oxidizing bacteria AOB and anaerobic ammonium-oxidizing bacteria AMX bacteria.

[0025] Preferably, in step (1), the water content of the anaerobic ammonium oxidation granular sludge and the nitrification / denitrification flocculent sludge for nitrogen removal is less than 90 wt%.

[0026] A higher sludge solid content can ensure the activity of the sludge.

[0027] Preferably, in step (1), the anaerobic ammonium oxidation granular sludge accounts for at least 50% of the total sludge mass; the inoculated anaerobic ammonium oxidation granules account for 45 - 55% of the total volume of the reactor, and the inoculated nitrification / denitrification flocculent sludge for nitrogen removal accounts for 25 - 35% of the total volume of the reactor.

[0028] Preferably, in step (1), the total volume of the biofilm reaction zone and the granular sludge reaction zone is not less than 80% of the total volume of the reactor, and the volume of the biofilm reaction zone is not greater than the sum of the bottom sludge bed and the granular sludge reaction zone; when the wastewater has an unfamiliar water quality and it is impossible to completely determine whether it can be stably granulated continuously, the volume ratio of the biofilm reaction zone to the sum of the bottom sludge bed and the granular sludge reaction zone is 0.8 - 1:1, and when the wastewater quality is determined to be able to granulate continuously and stably, the volume ratio of the two is 1:2.5 - 3.5.

[0029] Anaerobic ammonium oxidation granular sludge is formed in the biofilm reaction zone. The bottom sludge bed provides sludge matrix and bottom mud containing a small amount of anaerobic ammonium oxidation bacteria. Through high reflux ratio and screening by adapting to the environment for cultivation, the anaerobic ammonium oxidation granular sludge can grow on the biofilm reactor, enhancing the granulation degree of anaerobic ammonium oxidation bacteria and shortening the cultivation time.

[0030] Preferably, in step (1), the quality of the mixed wastewater meets the following requirements: the concentration of ammonia nitrogen and / or nitrite nitrogen does not exceed the maximum load that the anaerobic ammonium oxidation granular sludge in the reactor can bear; the conductivity is lower than the inhibition value of anaerobic ammonium oxidation bacteria in the anaerobic ammonium oxidation granular sludge in the reactor; the temperature is 33 - 37 °C; and the pH is 7.5 - 8.0.

[0031] Preferably, in step (1), the wastewater is pretreated before entering the water until the COD is lower than 1000 mg / L and the SS is lower than 1000 mg / L.

[0032] The influent with low COD can ensure the dominant growth of anaerobic ammonium oxidation bacteria, and too high SS will cause blockage of the reactor and deterioration of the microbial growth environment.

[0033] Preferably, the water treatment method is carried out in a water treatment system, which includes a reactor, a feed pump for feeding water into the bottom of the reactor, and a reflux pump for pumping out the circulating return water from the top of the reactor and re-introducing it from the bottom.

[0034] Inside the reactor:

[0035] The bottom is the bottom sludge bed, which is provided with a sludge discharge valve, an aerator, and a water distributor communicated with the feed pump;

[0036] The middle is the granular sludge reaction zone, which is provided with sensors for monitoring nitrite nitrogen / ammonia nitrogen / nitrate nitrogen / temperature / pH / dissolved oxygen / oxidation-reduction potential;

[0037] The top is the biofilm reaction zone and a three-phase separator. The biofilm reaction zone is provided with packing;

[0038] The three-phase separator is located in the biofilm reaction zone. Its top is provided with a water inlet and an effluent weir extending outside the reactor. The effluent weir is higher than the water inlet and lower than the liquid level in the reactor. A baffle separation zone for solid-liquid separation is provided in the channel between the water inlet and the effluent weir. The bottom of the three-phase separator is provided with a sludge outlet.

[0039] The water treatment system of the present invention comprises three major functional units, namely, a granular sludge reaction zone, a biofilm reaction zone, and a three-phase separator. The biofilm reaction zone is filled with packing materials. The three-phase separator of the present invention has downwardly turned water inlet for water inlet. Most of the gas is directly discharged from the top of the reactor. The water flow passes through a baffle separation zone, where the built-in baffles play a role in solid-liquid separation. The effluent of the three-phase separator overflows through an effluent weir. The granular sludge and other solid substances in the three-phase separator re-enter the lower part of the biofilm reaction zone through a sludge outlet. The height of the effluent weir is lower than the liquid level height of the reactor and higher than the height of the water inlet. In this three-phase separator, the wastewater passing through the biofilm reaction zone undergoes efficient solid-liquid separation through downwardly turned water inlet and the action of the baffles, reducing the loss of anaerobic ammonium oxidation granular sludge.

[0040] The aerator in the present invention operates with stage feedback through sensors. The anaerobic ammonium oxidation reaction mainly involves the reaction between nitrite and ammonium ions. The reaction equations involved in the entire cultivation process of anaerobic ammonium oxidation bacteria are as follows: NH 4 + +1.32NO 2 - +0.066HCO 3 - +0.13H + →1.02N 2 +0.26NO 3 - +2.03H 2 O + 0.066CH 2 O 0.5 N 0.15 (Anaerobic ammonium oxidation bacteria)

[0041] It is necessary to ensure the normal occurrence of nitritation reaction and the weakening of nitrification reaction in the whole reactor to obtain nitrite, so as to enable the normal progress of anaerobic ammonium oxidation reaction. The nitrite nitrogen and ammonia nitrogen probes read the concentrations of nitrite nitrogen and ammonia nitrogen in the reactor in real time to ensure that the ratio of the two is suitable for the survival of anaerobic ammonium oxidation bacteria. For anaerobic ammonium oxidation bacteria, ammonia nitrogen is not likely to inhibit anaerobic ammonium oxidation, while nitrite nitrogen is just the opposite. It will inhibit the growth of anaerobic ammonium oxidation bacteria under relatively low concentration conditions. Therefore, different aeration and reflux conditions need to be controlled at different cultivation stages.

[0042] Preferably, several two-fold baffles with an angle of 100 - 130° are provided in the baffle separation zone. The two-fold baffles are arranged in parallel, the center line of the two-fold baffles is parallel to the horizontal plane, and the gap between adjacent two-fold baffles forms the channel of the baffle separation zone.

[0043] Before the water flow enters the corrugated plate separation area of the three-phase separator, it needs to turn downward to the bottom of the corrugated plate separation area, and then overflow upward through the corrugated plate separation area for water outlet. This structural design easily causes sludge and suspended substances to stay in the corrugated plate separation area or before the corrugated plate separation area due to the instantaneous change in the hydraulic direction and the increase in the hydraulic path, strengthening the solid-liquid separation effect.

[0044] Preferably, the height-diameter ratio of the reactor is not less than 3:1.

[0045] A higher height-diameter ratio is beneficial for more quickly screening out granular sludge in the upflow reactor with circulation.

[0046] Preferably, the packing is fixed packing (IFAS) or suspended packing (MBBR).

[0047] Both IFAS and MBBR packings are suitable for biological enrichment in high-load environments. The biological carriers contained therein enable multiple different biological populations to act synergistically, enhancing the anaerobic ammonium oxidation process.

[0048] Compared with the prior art, the beneficial effects of the present invention are:

[0049] (1) The present invention couples the granular sludge biofilm method with flocculent sludge and divides the cultivation stage into four sub-stages. Throughout the cultivation stage, by adjusting condition parameters such as the circulation reflux ratio and aeration volume, it is easier to form granular sludge in the reactor, strengthening the denitrification effect of the reactor.

[0050] (2) Compared with the conventional anaerobic ammonium oxidation process, the present invention improves the granularity of anaerobic ammonium oxidation. The average granularity can reach more than 60%, the sludge running-off amount is reduced by 30%, and the activity of anaerobic ammonium oxidation granular sludge is ensured for a long time. The start-up time of the traditional anaerobic ammonium oxidation is shortened by more than 20%, and the average total nitrogen removal efficiency can reach more than 90%, solving the problems such as difficult start-up of the anaerobic ammonium oxidation process in the prior art, significant sludge loss, and limited application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 It is a schematic diagram of the system for treating sewage / wastewater by coupling granular sludge with biofilm method of flocculent sludge according to the present invention;

[0052] Figure 2 It is a schematic diagram of a structure of the three-phase separator according to the present invention.

[0053] The reference numerals are: reactor 1, inlet water pump 2, reflux pump 3, bottom sludge bed 4, sludge discharge valve 5, aerator 6, water distributor 7, granular sludge reaction area 8, sensor 9, biofilm reaction area 10, three-phase separator 11, packing 12, water inlet 111, water outlet weir 112, corrugated plate separation area 113, sludge outlet 114, second corrugated plate 115. Detailed implementation mode

[0054] The present invention will be further described below in conjunction with embodiments.

[0055] General embodiment

[0056] A water treatment method based on granular sludge coupled with flocculent sludge by biofilm method includes the following steps:

[0057] (1) Cultivation stage: Anaerobic ammonium oxidation granular sludge and nitrification / denitrification flocculent sludge are introduced into the reactor (the water content of both sludges is less than 90 wt%; the anaerobic ammonium oxidation granular sludge accounts for at least 50% of the total sludge mass; the anaerobic ammonium oxidation granules account for 45-55% of the total reactor capacity, and the nitrification / denitrification flocculent sludge accounts for 25-35% of the total reactor capacity). Pretreated wastewater (COD is less than 1000 mg / L, SS is less than 1000 mg / L) is introduced. After the appearance of circulating return water, it is mixed with the wastewater to form mixed wastewater (the concentration of ammonia nitrogen and / or nitrite nitrogen does not exceed the maximum tolerance of the anaerobic ammonium oxidation granular sludge; the conductivity is lower than the inhibition value of anaerobic ammonium oxidation bacteria; the temperature is 33-37 °C; pH = 7.5-8.0), and then introduced into the reactor. Under aeration, the water flow sequentially passes through the bottom sludge bed, granular sludge reaction zone, biofilm reaction zone and three-phase separator in the reactor. Part flows out from the three-phase separator, and the remaining part is used as circulating return water.

[0058] The cultivation stage is divided into four sub-stages:

[0059] The 1st - 30th day is the bacterial screening stage, adopting the intermittent aeration and intermittent feeding mode. When aerating, the dissolved oxygen in water is controlled at 0.5 - 0.7 mg / L, and when feeding, the reflux ratio of the circulating return water is 28 - 32%; in the bacterial screening stage, the intermittent aeration is to aerate for 50 - 70 min and then stop for 50 - 70 min; the intermittent feeding is to stop for 1.5 - 2.5 h after the single feed volume reaches the reactor capacity.

[0060] The 31st - 60th day is the activity change stage, adopting the continuous aeration and continuous feeding mode, controlling the dissolved oxygen in water at 0.7 - 1 mg / L, and the reflux ratio of the circulating return water is 28 - 32%.

[0061] The 61st - 90th day is the activity improvement stage, adopting the continuous aeration and continuous feeding mode, controlling the dissolved oxygen in water at 0.9 - 1.1 mg / L, and the reflux ratio of the circulating return water is 38 - 42%.

[0062] The 91st - 110th day is the activity stabilization stage, adopting the continuous aeration and continuous feeding mode, controlling the dissolved oxygen in water at 1 - 1.5 mg / L, and the reflux ratio of the circulating return water is 48 - 52%.

[0063] During the entire cultivation stage, if the concentration ratio of nitrite nitrogen to ammonia nitrogen > 1.5:1, immediately stop aeration and / or stop water inlet, and restart after recovery.

[0064] (2) Stable stage: Maintain the process in the stable activity stage.

[0065] Among them, the above water treatment method is carried out in a water treatment system, such as Figure 1 As shown, the water treatment system includes a reactor 1 (the height-diameter ratio is not less than 3:1), a water inlet pump 2 for inlet water at the bottom of the reactor, and a reflux pump 3 for pumping out the circulating return water from the top of the reactor and re-introducing it from the bottom.

[0066] Inside the reactor:

[0067] The bottom is the bottom sludge bed 4, equipped with a sludge discharge valve 5, an aerator 6, and a water distributor 7 connected to the water inlet pump.

[0068] The middle part is the granular sludge reaction zone 8, equipped with sensors 9 for monitoring nitrite nitrogen / ammonia nitrogen / nitrate nitrogen / temperature / pH / dissolved oxygen / oxidation-reduction potential.

[0069] The top is the biofilm reaction zone 10 and the three-phase separator 11. In the biofilm reaction zone, there are fillers 12 (fixed fillers IFAS or suspended fillers MBBR); if the form of suspended fillers is adopted, stainless steel flat sieves need to be set at the upper and lower limits of the flocculent sludge / biofilm respectively to ensure the operation of MBBR fillers and granular sludge in the corresponding areas. At the same time, a suitable sieve pore size (greater than or equal to 10 mm) is selected so that the lower flocculent sludge can pass through the sieve from the lower granular sludge reaction zone to the upper biofilm reaction zone. In the selection of MBBR fillers, the diameter should be greater than 10 mm, the number of holes is not less than 4, and the specific surface area is not less than 800 m 2 / m 3 , and the material should be HDPE.

[0070] Such as Figure 2 As shown, the three-phase separator is located in the biofilm reaction zone. Its top is provided with a water inlet 111 and an effluent weir 112 extending outside the reactor. The effluent weir is higher than the water inlet and lower than the liquid level in the reactor. In the channel between the water inlet and the effluent weir, there is a baffle separation zone 113 for solid-liquid separation. The bottom of the three-phase separator is provided with a sludge outlet 114. In the baffle separation zone, there are several two-baffle plates 115 at an angle of 100 - 130°. The two-baffle plates are arranged in parallel, the center line of the two-baffle plates is parallel to the horizontal plane, and the gap between adjacent two-baffle plates forms the channel of the baffle separation zone.

[0071] The total volume of the biofilm reaction zone and the granular sludge reaction zone is not less than 80% of the total volume of the reactor, and the volume of the biofilm reaction zone is not greater than the sum of the bottom sludge bed and the granular sludge reaction zone; when the wastewater has an unfamiliar quality and it is impossible to fully determine whether stable granulation can be sustained, the volume ratio of the biofilm reaction zone to the sum of the bottom sludge bed and the granular sludge reaction zone is 0.8 - 1:1, and when the wastewater quality is determined to be able to sustain stable granulation, the volume ratio of the two is 1:2.5 - 3.5.

[0072] Example 1

[0073] As Figure 1 shown, a water treatment system based on granular sludge coupled with biofilm method for flocculent sludge includes a reactor 1 (cylindrical, with a diameter of 1 m and a height of 4 m, and an effective volume of 2 m 3 ³), a feed pump 2 for feeding water into the bottom of the reactor, and a reflux pump 3 for pumping out the circulating return water from the top of the reactor and re-introducing it from the bottom.

[0074] Inside the reactor: at the bottom is a bottom sludge bed 4 with a volume of 0.4 m 3 ³, equipped with a sludge discharge valve 5, an aerator 6, and a water distributor 7 connected to the feed pump. In the middle is a granular sludge reaction zone 8 with a volume of 0.4 m 3 ³, equipped with a sensor 9 for monitoring nitrite nitrogen / ammonia nitrogen / nitrate nitrogen / temperature / pH / dissolved oxygen / oxidation-reduction potential. At the top are a biofilm reaction zone 10 and a three-phase separator 11. The volume of the biofilm reaction zone is 0.4 m 3 ³. In this area, there is a packing 12 (fixed packing IFAS), which uses elastic three-dimensional packing and is composed of EBCT three-dimensional packing of polypropylene. It is fixed at the upper end of the biofilm reaction zone, and then the fixed packing is evenly hung on the bracket. The length of the fixed packing shall not exceed the lower end of the biofilm reaction zone, and the distance between the stainless steel wires of the packing is 200 mm. As Figure 2 shown, the three-phase separator is located in the biofilm reaction zone. It has a water inlet 111 at the top and a weir 112 extending outside the reactor. The weir is higher than the water inlet and lower than the liquid level inside the reactor. The channel between the water inlet and the weir is a corrugated plate separation zone 113 for solid-liquid separation. The bottom of the three-phase separator has a sludge outlet 114. There are several two-corrugated plates 115 at 120° in the corrugated plate separation zone. The two-corrugated plates are arranged in parallel, the center line of the two-corrugated plates is parallel to the horizontal plane, and the gap between adjacent two-corrugated plates forms the channel of the corrugated plate separation zone.

[0075] A water treatment method based on granular sludge coupled with biofilm method for flocculent sludge includes the following steps:

[0076] (1) Cultivation stage: Anaerobic ammonium oxidation granular sludge and nitrification / denitrification flocculent sludge are introduced into the reactor bottom through an inlet pump (the water content of both sludges is 85 wt%; the inoculation amount of anaerobic ammonium oxidation granular sludge is 1 ton, and the inoculation amount of nitrification / denitrification flocculent sludge is 0.6 ton). Wastewater after pretreatment (the effluent of the anaerobic reactor in a certain landfill leachate treatment project, with an average effluent COD concentration of 900 mg / L, an average ammonia nitrogen concentration of 600 mg / L, an average total nitrogen concentration of 700 mg / L, and an average SS value of 600 mg / L) is fed in at a flow rate of 0.04 m 3 / h. The wastewater pumped into the reactor bottom is evenly distributed through a water distribution tray and then contacts the granular sludge bed above the water distribution tray. The maximum circulation flow rate of the reflux pump is 1 m 3 / h. After the circulating return water appears, the circulating return water is mixed with the wastewater to form mixed wastewater (the ammonia nitrogen and / or nitrite nitrogen concentration does not exceed the maximum tolerance of the anaerobic ammonium oxidation granular sludge; the conductivity is lower than the inhibition value of anaerobic ammonium oxidation bacteria; the temperature is 35°C; pH = 7.5 - 8.0), and then fed into the reactor. Under aeration, the water flow sequentially passes through the bottom sludge bed, granular sludge reaction zone, biofilm reaction zone, and three-phase separator in the reactor. Part of it flows out from the three-phase separator, and the remaining part is used as circulating return water.

[0077] During the water inlet process, the dissolved oxygen probe in the sensor is used to monitor the dissolved oxygen concentration in the system in real time, and jointly control with the blower to control the dissolved oxygen concentration in the reactor between 0.5 - 1.5 mg / L. The nitrite nitrogen and ammonia nitrogen probes read the nitrite nitrogen and ammonia nitrogen concentrations in the reactor in real time to ensure that the ratio of the two is 1:1. When the ratio of the two exceeds 1.5:1, it is necessary to adjust the blower air volume, reduce aeration, correspondingly reduce the dissolved oxygen in the system, thereby weakening the nitrification reaction, reducing the supply of nitrite nitrogen, or stopping the water inlet. Wait until the nitrite nitrogen in the reactor is gradually consumed, and then re-feed water. The aerator is cultivated through a four-stage cooperation with the reflux and water inlet modes.

[0078] In the bacterial screening stage (1 - 30 d), intermittent 1 h aeration and water inlet with low dissolved oxygen (0.7 mg / L) and high reflux ratio (30%, 0.6 m 3 / h circulation flow rate) are carried out. Among them, water is fed in once every 2 h, and the dissolved oxygen value DO in the reactor is feedback-linked and controlled around 0.7 mg / L through the dissolved oxygen real-time monitoring probe in the sensor. The aeration process is an intermittent mode of aeration for 1 h and stopping for 1 h.

[0079] In the activity change stage (31 - 60 d), long-term low dissolved oxygen (0.7 - 1 mg / L) and high reflux ratio (30%, 0.6 m 3Dynamic aeration and influent water (circulation flow rate of 0.8 m³ / h). The influent water mode is continuous influent. The dissolved oxygen value DO in the reactor is feedback-linked and controlled within 0.7 - 1 mg / L through the dissolved oxygen real-time monitoring probe in the sensor, and the aeration process is in continuous aeration mode.

[0080] In the activity improvement stage (61 - 90 d), carry out dynamic aeration and influent water with long-term low dissolved oxygen (1 mg / L) and high reflux ratio (40%, 0.8 m³ / h circulation flow rate). The influent water mode is continuous influent. The dissolved oxygen value DO in the reactor is feedback-linked and controlled at about 1 mg / L through the dissolved oxygen real-time monitoring probe in the sensor, and the aeration process is in continuous aeration mode. 3 Dynamic aeration and influent water (circulation flow rate of 0.8 m³ / h). The influent water mode is continuous influent. The dissolved oxygen value DO in the reactor is feedback-linked and controlled within about 1 mg / L through the dissolved oxygen real-time monitoring probe in the sensor, and the aeration process is in continuous aeration mode.

[0081] In the activity stable stage (91 - 110 d), carry out dynamic aeration and influent water with long-term relatively low dissolved oxygen (1 - 1.5 mg / L) and high reflux ratio (50%, 1 m³ / h circulation flow rate). The influent water mode is continuous influent. The dissolved oxygen value DO in the reactor is feedback-linked and controlled at about 1 - 1.5 mg / L through the dissolved oxygen real-time monitoring probe in the sensor, and the aeration process is in continuous aeration mode. 3 Dynamic aeration and influent water (circulation flow rate of 1 m³ / h). The influent water mode is continuous influent. The dissolved oxygen value DO in the reactor is feedback-linked and controlled within about 1 - 1.5 mg / L through the dissolved oxygen real-time monitoring probe in the sensor, and the aeration process is in continuous aeration mode.

[0082] The pH probe in the sensor monitors the pH change in the reactor in real time. The monitored and controlled pH range is between 7.5 and 8, and the reactor temperature is controlled at 35 ± 2 °C.

[0083] In the above water treatment system, the sludge at the bottom is dispersed through bottom aeration and rises to the granular sludge reaction zone through a reflux pump. Ammonia nitrogen and nitrite nitrogen in the wastewater will preferentially react for denitrification in the granular sludge reaction zone, and the ammonia nitrogen and nitrite nitrogen that are not completely removed will continue to complete the remaining denitrification in the biofilm reaction zone. The flocculent sludge generated in the granular sludge zone will float to the biofilm reaction zone along with the bubbles generated in the reactor, attach to the packing to complete the interception of part of the sludge, and at the same time create a second denitrification area.

[0084] When the wastewater completes the reaction in the granular sludge reaction zone and the biofilm reaction zone, nitrogen gas directly escapes from the top of the reactor. After the wastewater enters through the specially designed three-phase separator in a downward-turning manner, solid-liquid separation is carried out through the baffle area in the separator. After the separation is completed, the granular sludge and part of the flocculent sludge return to the lower part of the biofilm reaction zone again, and the effluent water is discharged to the effluent water tank through the effluent weir above the three-phase separator. This downward-turning influent three-phase separator effectively separates the three phases and reduces the sludge running situation in the reactor.

[0085] Finally, the average concentration of ammonia nitrogen in the effluent water is 31 mg / L, the average concentration of total nitrogen is 38 mg / L, no nitrite nitrogen is detected in the effluent water, the ammonia nitrogen removal rate is 95.2%, and the total nitrogen removal rate is 94.3%, which is much higher than that of the conventional anaerobic ammonium oxidation system.

[0086] After the system had been running for one year, it operated stably. A large amount of granulated anaerobic ammonium-oxidizing bacteria could be collected from the sludge discharge valve. Take 0.4 m 3 of anaerobic ammonium-oxidizing granular sludge as the seed sludge. Before taking the sludge, turn off all pumps. The granular sludge is directly discharged from the sludge outlet and stored in a plastic bucket with a lid.

[0087] Comparative Examples 1-3

[0088] The differences between Comparative Examples 1-3 and Example 1 are only in the aeration and influent parameters during the cultivation stage, as shown in the following table:

[0089]

[0090] In Comparative Example 1, a continuous aeration and influent mode with no difference was adopted throughout the process. The parameters were low dissolved oxygen (0.7 mg / L) and high reflux ratio (1 m 3 / h). Since a low dissolved oxygen mode was adopted throughout the process, it was easy to cause insufficient supply of nitrite in the early stage, resulting in the inability of ammonia nitrogen to be converted into nitrite in time to create a sufficient ratio of nitrite and ammonia nitrogen for anaerobic ammonium-oxidizing bacteria. Eventually, the removal rates of ammonia nitrogen and total nitrogen in the system decreased.

[0091] In Comparative Example 2, a continuous aeration and influent mode with no difference was adopted throughout the process. The parameters were low dissolved oxygen (1.5 mg / L) and high reflux ratio (1 m 3 / h). Since a high dissolved oxygen mode was adopted throughout the process, it was easy to cause excessive supply of nitrite in the early stage, resulting in too high a ratio of nitrite and ammonia nitrogen, and too high a proportion of nitrite in the system. And a long-term high dissolved oxygen mode in the early stage of cultivating anaerobic ammonium-oxidizing bacteria was likely to cause slower growth of anaerobic ammonium-oxidizing bacteria. Eventually, the removal rates of ammonia nitrogen and total nitrogen in the system decreased and there was a small amount of nitrite residue.

[0092] In Comparative Example 3, intermittent aeration (interval 1 h) with low dissolved oxygen (0.7 mg / L) and high reflux ratio (0.6 m 3 / h) and intermittent influent (interval 2 h) were adopted from day 1 to day 30, continuous aeration and influent mode with low dissolved oxygen (0.7 - 1 mg / L) and high reflux ratio (0.6 m 3 / h) were adopted from day 31 to day 60, and continuous aeration and influent mode with relatively low dissolved oxygen (1 - 1.5 mg / L) and high reflux ratio (1 m 3The continuous aeration and influent mode of ( / h). Among them, directly adopting a mode with higher dissolved oxygen and a high circulation ratio during the active growth period of anaerobic ammonium oxidation bacteria is likely to cause periodic nitrite accumulation during the cultivation process. Since the anaerobic ammonium oxidation bacteria have a slow growth rate and cannot quickly adapt to this suddenly increasing process, there are not enough anaerobic ammonium oxidation bacteria to adapt to this environment. Eventually, the ammonia nitrogen and total nitrogen removal rates in the system decrease and there is a small amount of nitrite residue.

[0093] Example 2

[0094] A water treatment system based on granular sludge coupled with flocculent sludge by biofilm method, including a reactor (cylindrical, with a diameter of 1 m and a height of 4 m, and an effective volume of 2 m 3 ), a feed pump for feeding water into the bottom of the reactor, and a reflux pump for pumping out the circulating return water from the top of the reactor and re-introducing it from the bottom.

[0095] Inside the reactor: The bottom is a bottom sludge bed of 0.4 m 3 , equipped with a sludge discharge valve, an aerator, and a water distributor connected to the feed pump. The middle is a granular sludge reaction zone with a volume of 1.2 m 3 , equipped with sensors for monitoring nitrite nitrogen / ammonia nitrogen / nitrate nitrogen / temperature / pH / dissolved oxygen / oxidation-reduction potential. The top is a biofilm reaction zone and a three-phase separator. The volume of the biofilm reaction zone is 0.4 m 3 , and in this area, there are fillers (suspended fillers MBBR)

[0096] Elastic three-dimensional fillers are used. Stainless steel flat sieves are respectively arranged at the upper and lower limits of the biofilm reaction zone to ensure the operation of the suspended fillers and granular sludge in the corresponding areas. At the same time, a suitable sieve pore diameter (10 mm) is selected so that the lower flocculent sludge can pass through the sieve from the lower reaction zone to the upper reaction zone. In the selection of MBBR fillers, the diameter is 10 mm, the number of holes is 10, and the specific surface area is 1200 m 2 / m 3 , and the material is HDPE. The three-phase separator is the same as in Example 1.

[0097] A water treatment method based on granular sludge coupled with flocculent sludge by biofilm method, including the following steps:

[0098] (1) Cultivation stage: 0.4 tons of anaerobic ammonium oxidation granular sludge cultivated in Example 1 is connected to the bottom of the reactor through the feed pump, with a flow rate of 0.04 m 3The flow rate of / h is introduced into the pretreated wastewater (the effluent of the anaerobic reactor in a certain landfill leachate treatment project, with an average effluent COD concentration of 1000 mg / L, an average ammonia nitrogen concentration of 850 mg / L, an average total nitrogen concentration of 900 mg / L, and an average SS value of 750 mg / L). The wastewater pumped to the bottom of the reactor is evenly distributed by a water distribution tray and then contacts the granular sludge bed above the water distribution tray. The maximum circulating flow rate of the reflux pump is 1 m 3 / h. After the circulating return water appears, the circulating return water is mixed with the wastewater to form mixed wastewater (the ammonia nitrogen and / or nitrite nitrogen concentration does not exceed the maximum tolerance of the anaerobic ammonium oxidation granular sludge; the conductivity is lower than the inhibition value of anaerobic ammonium oxidizing bacteria; the temperature is 35 °C; pH = 7.5 - 8.0), and then it is introduced into the reactor. Under aeration, the water flow sequentially passes through the bottom sludge bed, granular sludge reaction zone, biofilm reaction zone, and three-phase separator in the reactor. Part of it flows out from the three-phase separator, and the remaining part is used as circulating return water.

[0099] During the water inlet process, the dissolved oxygen probe in the sensor is used to monitor the dissolved oxygen concentration in the system in real time, and jointly with the blower, the dissolved oxygen concentration in the reactor is controlled between 0.5 - 1.5 mg / L. The nitrite nitrogen and ammonia nitrogen probes read the nitrite nitrogen and ammonia nitrogen concentrations in the reactor in real time to ensure that the ratio of the two is 1:1. When the ratio of the two exceeds 1.5:1, it is necessary to adjust the air volume of the blower, reduce aeration, and correspondingly reduce the dissolved oxygen in the system, thereby weakening the nitrification reaction, reducing the supply of nitrite nitrogen, or stopping the water inlet. Wait until the nitrite nitrogen in the reactor is gradually consumed, and then re-introduce water. The aerator is cultivated through a four-stage cooperation with the reflux and water inlet modes.

[0100] In the bacterial screening stage (1 - 30 d), intermittent aeration and water inlet with low dissolved oxygen (0.7 mg / L) and high reflux ratio (30%, 0.6 m 3 / h circulating flow rate) for 1 h are carried out. Among them, water is introduced every 2 h, and the dissolved oxygen value DO in the reactor is feedback-linked and controlled near 0.7 mg / L through the dissolved oxygen real-time monitoring probe in the sensor. The aeration process is an intermittent mode of aeration for 1 h and stopping for 1 h.

[0101] In the activity change stage (31 - 60 d), dynamic aeration and water inlet with long-term low dissolved oxygen (0.7 - 1 mg / L) and high reflux ratio (30%, 0.6 m 3 / h circulating flow rate) are carried out. Among them, the water inlet mode is continuous water inlet, and the dissolved oxygen value DO in the reactor is feedback-linked and controlled within 0.7 - 1 mg / L through the dissolved oxygen real-time monitoring probe in the sensor. The aeration process is a continuous aeration mode.

[0102] In the activity improvement stage (61 - 90 d), long-term low dissolved oxygen (1 mg / L) and high reflux ratio (40%, 0.8 m 3Dynamic aeration and influent for the / h recycle flow rate). The influent mode is continuous influent, and the dissolved oxygen value DO in the reactor is feedback-linked and controlled by the dissolved oxygen real-time monitoring probe in the sensor to about 1 mg / L of dissolved oxygen. The aeration process is a continuous aeration mode.

[0103] During the active stable stage (91 - 110 d), dynamic aeration and influent with a long-term low dissolved oxygen (1 - 1.5 mg / L) and a high reflux ratio (50%, 1 m 3 / h recycle flow rate) are carried out. The influent mode is continuous influent, and the dissolved oxygen value DO in the reactor is feedback-linked and controlled by the dissolved oxygen real-time monitoring probe in the sensor to about 1 - 1.5 mg / L of dissolved oxygen. The aeration process is a continuous aeration mode.

[0104] The pH probe in the sensor monitors the pH change in the reactor in real time. The monitored and controlled pH range is between 7.5 and 8, and the reactor temperature is controlled at 35 ± 2 °C.

[0105] Finally, the average concentration of ammonia nitrogen in the effluent is 46 mg / L, the average concentration of total nitrogen is 61 mg / L, no nitrite nitrogen is detected in the effluent, the ammonia nitrogen removal rate is 95%, and the total nitrogen removal rate is 93.3%, which is much higher than that of a conventional anaerobic ammonia oxidation system.

[0106] After the system has been operating for 6 months, the system operates stably. Take 0.4 m from the reactor 3 , and when commissioning and starting up, the inoculated sludge is directly pumped into the reactor through the influent pump of the influent tank. After the system starts up after operating for 6 months, it meets the conditions for inoculation as seed sludge. The anaerobic ammonia oxidation granular sludge is discharged from the sludge discharge valve. Every 6 months, the granular sludge reactor and Example 1 can provide about 1 m of inoculated granular sludge 3 .

[0107] In the present invention, the raw materials and equipment used, unless otherwise specified, are common raw materials and equipment in the art; the methods used in the present invention, unless otherwise specified, are conventional methods in the art.

[0108] The above are only the preferred embodiments of the present invention and do not impose any limitations on the present invention. Any simple modifications, changes, and equivalent transformations made to the above embodiments according to the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A water treatment method based on granular sludge coupled with flocculent sludge by biofilm method, characterized in that it includes: (1) Cultivation stage: Anaerobic ammonium oxidation granular sludge and nitrification / denitrification flocculent sludge are introduced into the reactor. After wastewater is introduced and circulating return water appears, it is mixed with the wastewater to form mixed wastewater and then introduced into the reactor. Under aeration, the water flow sequentially passes through the bottom sludge bed, granular sludge reaction zone, biofilm reaction zone and three-phase separator in the reactor. Part of it flows out from the three-phase separator, and the remaining part is used as circulating return water; The cultivation stage is sequentially divided into: The 1st - 30th day is the bacterial screening stage, adopting intermittent aeration and intermittent water inlet mode. When aerating, the dissolved oxygen in water is 0.5 - 0.7 mg / L, and when inletting water, the reflux ratio of the circulating return water is 28 - 32%; The 31st - 60th day is the activity change stage, adopting continuous aeration and continuous water inlet mode, controlling the dissolved oxygen in water to be 0.7 - 1 mg / L, and the reflux ratio of the circulating return water is 28 - 32%; The 61st - 90th day is the activity improvement stage, adopting continuous aeration and continuous water inlet mode, controlling the dissolved oxygen in water to be 0.9 - 1.1 mg / L, and the reflux ratio of the circulating return water is 38 - 42%; The 91st - 110th day is the activity stabilization stage, adopting continuous aeration and continuous water inlet mode, controlling the dissolved oxygen in water to be 1 - 1.5 mg / L, and the reflux ratio of the circulating return water is 48 - 52%; (2) Stabilization stage: Maintain the process of the activity stabilization stage.

2. The water treatment method according to claim 1, characterized in that: In step (1), In the bacterial screening stage, the intermittent aeration is aerating for 50 - 70 min and stopping for 50 - 70 min; the intermittent water inlet is stopping for 1.5 - 2.5 h after the single water inlet volume reaches the reactor capacity; In the whole cultivation stage, if the concentration ratio of nitrite nitrogen to ammonia nitrogen > 1.5:1, immediately stop aeration and / or stop water inlet, and restart after recovery.

3. The water treatment method according to claim 1 or 2, characterized in that: In step (1), the anaerobic ammonium oxidation granular sludge accounts for at least 50% of the total sludge mass; the inoculated anaerobic ammonium oxidation granules account for 45 - 55% of the total reactor capacity, and the inoculated nitrification / denitrification flocculent sludge accounts for 25 - 35% of the total reactor capacity.

4. The water treatment method according to claim 1 or 2, characterized in that: In step (1), the total volume of the biofilm reaction zone and the granular sludge reaction zone is not less than 80% of the total reactor volume, and the volume of the biofilm reaction zone is not greater than the sum of the bottom sludge bed and the granular sludge reaction zone; when the wastewater is of unknown quality and it is impossible to completely determine whether it can be stably granulated continuously, the volume ratio of the biofilm reaction zone to the sum of the granular sludge reaction zone and the bottom sludge bed is 0.8 - 1:1, and when the wastewater quality is determined to be able to granulate stably and continuously, the volume ratio of the two is 1:2.5 - 3.

5.

5. The water treatment method according to claim 1 or 2, characterized in that: In step (1), the wastewater is pretreated before inletting until the COD is lower than 1000 mg / L and the SS is lower than 1000 mg / L.

6. The water treatment method according to claim 1 or 2, It is characterized in that: In step (1), the water quality of the mixed wastewater meets the following requirements: The concentration of ammonia nitrogen and / or nitrite nitrogen does not exceed the maximum load that can be tolerated by the anaerobic ammonium oxidation granular sludge in the reactor; The conductivity is lower than the inhibition value of anaerobic ammonium oxidizing bacteria in the anaerobic ammonium oxidation granular sludge in the reactor; The temperature is 33 - 37 °C; The pH is 7.5 - 8.

0.

7. The water treatment method according to claim 1, It is characterized in that: It is carried out in a water treatment system, and the water treatment system includes a reactor, a feed pump for feeding water into the bottom of the reactor, and a reflux pump for pumping out the circulating return water from the top of the reactor and re-introducing it from the bottom; Inside the reactor: The bottom is a bottom sludge bed, provided with a sludge discharge valve, an aerator, and a water distributor communicated with the feed pump; The middle part is a granular sludge reaction zone, provided with sensors for monitoring nitrite nitrogen / ammonia nitrogen / nitrate nitrogen / temperature / pH / dissolved oxygen / oxidation-reduction potential; The top is a biofilm reaction zone and a three-phase separator. The biofilm reaction zone is provided with packing; The three-phase separator is located in the biofilm reaction zone. The top of the three-phase separator is provided with a water inlet and an effluent weir extending outside the reactor. The effluent weir is higher than the water inlet and lower than the liquid level in the reactor. A baffle separation zone for solid-liquid separation is provided in the channel between the water inlet and the effluent weir. The bottom of the three-phase separator is provided with a sludge outlet.

8. The water treatment method according to claim 7, It is characterized in that: The baffle separation zone is provided with a number of two-baffle plates at an angle of 100 - 130°. The two-baffle plates are arranged in parallel. The center line of the two-baffle plates is parallel to the horizontal plane. The gap between adjacent two-baffle plates forms the channel of the baffle separation zone.

9. The water treatment method according to claim 8, It is characterized in that: The height-diameter ratio of the reactor is not less than 3:

1.

10. The water treatment method according to claim 8, It is characterized in that: The packing is fixed packing or suspended packing.

Images