Denitrification process for high-ammonia-nitrogen wastewater based on anaerobic ammonia oxidation

Abstract

The application discloses a high-ammonia-nitrogen wastewater denitrification treatment process based on anaerobic ammonia oxidation, which comprises pretreatment, short-range nitrification, two-stage anaerobic ammonia oxidation combined with short-range denitrification, deep purification and effluent backflow regulation and control; the pretreatment removes suspended solids, grease and toxic organic matters; the short-range nitrification precisely regulates ammonia oxidation rate; a first-stage anaerobic ammonia oxidation reactor completes main denitrification by using immobilized composite carriers; a second-stage anaerobic ammonia oxidation reactor realizes nitrate reduction and nitrite regeneration by using endogenous carbon sources in raw water; a sulfur autotrophic denitrification or MBR membrane is matched in the rear end to realize deep purification, and an effluent backflow system is arranged to buffer high-ammonia-nitrogen load of influent water. The application realizes autotrophic denitrification by multi-stage microbial flora, does not need external organic carbon source in the whole process, reduces aeration energy consumption by more than 40%, greatly reduces sludge production, and stably realizes total nitrogen removal rate of more than 95%, and is suitable for low-cost stable deep denitrification of high-ammonia-nitrogen low C / N wastewater such as landfill leachate, breeding, chemical industry, sludge digestion liquid and the like.

Description

Technical Field

[0001] This invention relates to the field of high ammonia nitrogen wastewater treatment technology, specifically a high ammonia nitrogen wastewater denitrification treatment process based on anaerobic ammonia oxidation. Background Technology

[0002] High ammonia nitrogen wastewater is a typical pollutant wastewater generated during industrial production, livestock and poultry breeding, and landfilling. It is characterized by high ammonia nitrogen concentration, large fluctuations in water quality, poor biodegradability, and strong toxicity of pollutants. Direct discharge will cause eutrophication, algal blooms, and oxygen deficiency, resulting in blackening and foul odor in the water, which will seriously damage the aquatic ecological environment and endanger human health.

[0003] Anaerobic ammonia oxidation (AAO) is a rapidly developing novel biological nitrogen removal technology in recent years. Its basic principle is that under anaerobic conditions, anaerobic ammonia-oxidizing bacteria use ammonia nitrogen as an electron donor and nitrite as an electron acceptor, simultaneously converting both into nitrogen gas. Compared with traditional processes, AAO can save approximately 62.5% of aeration volume, requires no external carbon source, and has a low sludge yield, exhibiting significant energy-saving and consumption-reducing advantages. However, this technology still faces many challenges in practical engineering applications: (1) The doubling cycle of anaerobic ammonia oxidizing bacteria is as long as 10-14 days, the reactor start-up and acclimatization period is long, and the industrialization efficiency is low; (2) Short-range nitrification systems are difficult to stably inhibit nitrite-oxidizing bacteria (NOB), resulting in an imbalance in nitrite supply and nitrite accumulation that inhibits the activity of anaerobic ammonia-oxidizing bacteria; (3) Suspended solids, oils, and macromolecular organic matter in raw water will competitively inhibit anaerobic ammonia-oxidizing bacteria; (4) The main reaction of anaerobic ammonia oxidation will generate about 11% nitrate nitrogen. The total nitrogen removal rate of a single anaerobic ammonia oxidation unit is limited, and the total nitrogen in the effluent is difficult to meet the standard stably.

[0004] Therefore, there is an urgent need to develop a process that combines pretreatment and impurity removal, short-cut nitrification, multi-stage anaerobic ammonia oxidation with denitrification, and deep purification to achieve a high ammonia nitrogen wastewater denitrification solution that is fast to start up, stable in operation, has a high total nitrogen removal rate, and low operation and maintenance costs. This has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to solve the problems of long start-up cycle, difficulty in controlling the nitrite substrate ratio, organic matter inhibition, and residual nitrate in the effluent in the existing anaerobic ammonia oxidation process. It provides an integrated, multi-stage synergistic anaerobic ammonia oxidation denitrification process that does not require external organic carbon sources throughout the process, achieves a stable total nitrogen removal rate of ≥95%, reduces aeration energy consumption and sludge production, and is suitable for the industrial treatment of high-concentration, high-ammonia nitrogen wastewater with large water quality fluctuations.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A high-ammonia nitrogen wastewater denitrification process based on anaerobic ammonia oxidation includes the following steps: Step S1. Preprocessing High ammonia nitrogen wastewater is sequentially processed through a screen for slag removal, primary sedimentation, and air flotation for oil removal to remove suspended solids and grease. It is then sent to a pH adjustment tank to adjust the pH to 7.2-8.0, and then enters a hydrolysis acidification tank to hydrolyze large molecular organic matter and reduce organic inhibition. Step S2. Short-cut nitrification The hydrolyzed and acidified effluent enters a short-cut nitrification reactor, where DO is controlled at 0.3-1.0 mg / L, temperature at 30-35℃, pH at 7.5-8.0, and hydraulic retention time at 4-8 h. The ammonia nitrogen oxidation rate is controlled at 50%-60%, resulting in a nitrite to ammonia nitrogen molar ratio of 1.0-1.3:1 in the effluent. Nitrite-oxidizing bacteria are inhibited by controlling free ammonia at 0.1-1.0 mg / L. Step S3. Primary anaerobic ammonium oxidation for denitrification The short-cut nitrification effluent enters the primary anaerobic ammonium oxidation reactor, which is filled with a composite sludge system of anaerobic ammonium oxidation granular sludge and biological carrier. Under anaerobic and light-proof conditions, the denitrification reaction of ammonia nitrogen and nitrite is completed, generating nitrogen gas and nitrate. Step S4. Secondary anaerobic ammonium oxidation combined with short-cut denitrification The effluent from the primary anaerobic ammonia oxidation is sent to the intermediate equalization tank and mixed with some raw water at a volume ratio of 3:1-5:1. The organic matter in the raw water is used to reduce nitrate to nitrite. The mixture enters the secondary anaerobic ammonia oxidation reactor, where the remaining ammonia nitrogen and regenerated nitrite undergo anaerobic ammonia oxidation again. Step S5. Deep purification and mud-water separation The effluent from the secondary anammox reactor is sent to a deep purification unit to remove residual nitrate nitrogen and suspended solids. After sludge-water separation, part of the settled sludge is returned to the primary anammox reactor at a return ratio of 20%-40%. Step S6. Reflux stabilization control The supernatant after deep purification is returned to the pretreatment inlet at a rate of 20%-95% to dilute the ammonia nitrogen in the inlet water and buffer fluctuations in water quality and quantity. The remaining effluent is discharged in compliance with standards.

[0007] Furthermore, in step S1, the hydraulic retention time in the hydrolysis acidification tank is 6-12 hours, and the tank is filled with 30%-50% combined packing material; when pretreating wastewater with high suspended solids and heavy metals, a coagulation and sedimentation process is added, with 30-50 mg / L of polyaluminum chloride and 2-5 mg / L of polyacrylamide added, the mixture is stirred for 15-20 minutes, and the sediment is allowed to stand for 30-40 minutes.

[0008] Furthermore, in step S2, the short-cut nitrification reactor is a sequencing batch reactor or a continuous flow reactor, with a microporous aeration device and a stirring device installed at the bottom; the concentration of nitrified sludge in the reactor is 3000-4000 mg / L, and the sludge age is controlled at 8-10 days.

[0009] Furthermore, in step S3, the volume ratio of anaerobic ammonia oxidation granular sludge to biological carrier in the composite sludge system is 2:1-3:1; the granular sludge particle size is 0.5-3.0 mm, and the MLSS is 5000-10000 mg / L; the biological carrier is selected from one or more of polyurethane foam, hollow suspended packing, and biological rope, with a specific surface area of ​​500-2000 m³ / m²; the primary anaerobic ammonia oxidation reactor is controlled at a temperature of 30-35℃, pH 7.0-8.0, and hydraulic retention time of 6-12 h, with an influent ammonia nitrogen load ≤1.5 kgN / (m³・d).

[0010] Furthermore, in step S4, the secondary anaerobic ammonia oxidation reactor is filled with 20%-40% anaerobic ammonia oxidation biofilm packing material, the dissolved oxygen is controlled to be <0.2mg / L, and the hydraulic retention time is 4-8h.

[0011] Furthermore, in step S5, the deep purification unit is a sedimentation tank with built-in sulfur autotrophic denitrification packing, which relies on sulfur autotrophic bacteria to remove residual nitrates.

[0012] Furthermore, in step S5, the deep purification unit is a post-aerobic MBR membrane reactor, with DO controlled at 2-4 mg / L, hydraulic retention time at 2-4 h, hollow fiber membrane pore size at 0.1-0.4 μm, MBR sludge return ratio at 50%-95%, and sludge returned to the hydrolysis acidification tank or short-cut nitrification reactor.

[0013] Furthermore, in step S6, the recirculation ratio is adjusted according to the influent ammonia nitrogen concentration: 20%-40% recirculation for low-load influent and 50%-95% recirculation for high-impact load influent.

[0014] Furthermore, the entire process is equipped with a PLC intelligent control system, which monitors and automatically adjusts dissolved oxygen concentration, temperature, pH, hydraulic retention time, and effluent recirculation ratio online to achieve automated and stable operation.

[0015] The treatment system for treating high ammonia nitrogen wastewater based on anaerobic ammonia oxidation includes, in sequence along the water flow direction, a pretreatment unit, a short-cut nitrification reactor, a primary anaerobic ammonia oxidation reactor, an intermediate equalization tank, a secondary anaerobic ammonia oxidation reactor, and a deep purification unit, which are connected by pipelines. The pretreatment unit includes a bar screen, a primary sedimentation tank, an air flotation oil removal device, a pH adjustment tank, and a hydrolysis acidification tank connected in series. The intermediate adjustment tank is equipped with a raw water inlet pipe and a primary anaerobic ammonia oxidation effluent inlet pipe. The deep purification unit is equipped with a product water pipe, a sludge return pipe, and an effluent return pipe. All biochemical reactors are equipped with online pH monitoring, DO monitoring, temperature monitoring, and constant temperature control devices. The two-stage anaerobic ammonia oxidation reactors are equipped with a three-phase separator.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: This high ammonia nitrogen wastewater denitrification treatment process based on anaerobic ammonia oxidation has the following advantages: 1. Pretreatment multi-stage impurity removal: through grid, flotation and hydrolysis acidification, suspended solids, oils and macromolecular organic matter are removed in a coordinated manner, eliminating the competitive inhibition of organic matter on anaerobic ammonia oxidizing bacteria and greatly improving the system's anti-interference ability; 2. Short-cut nitrification stabilizes the substrate, and NOB is stabilized and suppressed by the combined regulation of DO, free ammonia, and sludge age. The ammonia nitrogen oxidation rate is precisely controlled to obtain the ammonia nitrogen / nitrite ratio suitable for anaerobic ammonia oxidation, thus avoiding the accumulation and inhibition of nitrite. 3. Two-stage anaerobic ammonium oxidation combined with short-cut denitrification solves the problem of nitrate residue. The primary stage is for nitrogen removal, and the secondary stage utilizes the carbon source from the raw water to reduce nitrate and regenerate nitrite for secondary nitrogen removal, achieving a stable total nitrogen removal rate of ≥95%; combined with immobilized composite carriers and gradient loading acclimatization, the reactor start-up period is shortened to less than 30 days; 4. No external organic carbon source is required throughout the process, significantly reducing operating costs. Compared to traditional nitrification and denitrification, carbon source and reagent costs are reduced by 95%; aeration energy consumption in low-oxygen aeration mode is reduced by 40%-50%; and the sludge production rate of autotrophic microorganisms is only 1 / 3 of that of traditional processes, significantly reducing sludge disposal costs. 5. Recirculation buffering and deep purification provide dual protection. The effluent is recirculated to dilute the high-load influent and buffer water quality fluctuations; sulfur autotrophic denitrification or MBR membrane post-treatment provides dual protection for effluent water quality, with ammonia nitrogen ≤15mg / L and total nitrogen consistently meeting the standards; 6. High degree of automation and wide applicability. The entire process is controlled by PLC linkage, which controls DO, pH, temperature, reflux ratio, and hydraulic retention time, making operation and maintenance simple; it is suitable for various high ammonia nitrogen wastewater with ammonia nitrogen of 500-2000mg / L and COD ≤200mg / L, and has strong industrial versatility. Detailed Implementation

[0017] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] This invention includes a first aspect: a process for denitrification of high-ammonia nitrogen wastewater based on anaerobic ammonia oxidation, comprising the following steps: Step S1. Wastewater pretreatment High ammonia nitrogen wastewater passes through a screen for slag removal and primary sedimentation to remove large suspended solids. The effluent then enters an air flotation oil removal device to remove floating oil and emulsified grease. The air flotation effluent enters a pH adjustment tank where acids and alkalis are added to adjust the pH to 7.2-8.0. After adjustment, the wastewater enters a hydrolysis acidification tank with a hydraulic retention time of 6-12 hours. The tank is filled with 30%-50% combined packing material to hydrolyze large, recalcitrant organic molecules into smaller molecules, reducing the inhibitory effect of organic load on anaerobic ammonia oxidizing bacteria. For wastewater with high suspended solids and heavy metals, add a coagulation and sedimentation process, add 30-50 mg / L polyaluminum chloride and 2-5 mg / L polyacrylamide, stir for 15-20 minutes, let it stand and settle for 30-40 minutes to remove colloidal and heavy metal toxic substances. Step S2. Short-cut nitrification The hydrolysis and acidification effluent is fed into a short-cut nitrification reactor, which is either a sequencing batch reactor (SBR) or a continuous flow reactor. The reactor is equipped with a microporous aeration and stirring device at the bottom. Process parameters are controlled as follows: dissolved oxygen (DO): 0.3-1.0 mg / L; temperature: 30-35℃; pH: 7.5-8.0; hydraulic retention time: 4-8 h; sludge age: 8-10 days; sludge concentration: 3000-4000 mg / L. Ammonia nitrogen oxidation rate is controlled at 50%-60% through online water quality monitoring. The effluent nitrite to ammonia nitrogen molar ratio is adjusted to 1.0-1.3:1, and the mass concentration ratio is 1:1.1-1.32. Simultaneously, the free ammonia concentration is controlled at 0.1-1.0 mg / L to continuously inhibit NOB activity, achieving stable nitrite accumulation and providing the optimal substrate for anaerobic ammonia oxidation. Step S3. Primary anaerobic ammonium oxidation for denitrification The effluent from short-cut nitrification enters the primary anaerobic ammonium oxidation reactor, which is filled with a composite sludge system: anaerobic ammonium oxidation granular sludge (particle size 0.5-3.0mm, MLSS 5000-10000mg / L) combined with a biological carrier, with a volume ratio of 2:1-3:1; the biological carrier is selected from polyurethane foam, hollow suspended packing or biological rope, with a specific surface area of ​​500-2000m² / m³. Process parameter control: temperature 30-35℃, pH 7.0-8.0, hydraulic retention time 6-12h, influent ammonia nitrogen load ≤1.5kgN / (m³・d), light-proof and anaerobic environment; anaerobic ammonia-oxidizing bacteria use NH4⁺ as electron donor and NO2⁻ as electron acceptor to convert most ammonia nitrogen and nitrite into N2, with a small amount of NO3⁻ as a byproduct; Step S4. Secondary anaerobic ammonium oxidation combined with short-cut denitrification for deep nitrogen removal. The effluent from the primary anaerobic ammonium oxidation is sent to the intermediate equalization tank and mixed with some raw water at a volume ratio of 3:1-5:1. The raw water uses small molecule organic matter as an electron donor to carry out short-cut denitrification, reducing the NO3⁻ generated in the primary reaction to NO2⁻. The mixed liquor is fed into a secondary anaerobic ammonia oxidation reactor, which is filled with 20%-40% anaerobic ammonia oxidation biofilm packing. The DO is controlled to be <0.2mg / L, and the hydraulic retention time is 4-8h. The newly generated nitrite reacts with the remaining ammonia nitrogen again in an anaerobic ammonia oxidation reaction, eliminating nitrate accumulation in situ and significantly reducing the total nitrogen in the effluent. Step S5. Deep purification and mud-water separation The effluent from the secondary anaerobic ammonia oxidation process enters the advanced treatment unit, which adopts either Option 1 or Option 2: Option 1: Built-in sulfur-based autotrophic denitrification packing material, no external carbon source required, sulfur autotrophic denitrification precipitation and purification, completely remove residual nitrate, complete sludge-water separation in the sedimentation tank, and part of the settled sludge is returned to the primary anaerobic ammonia oxidation reactor to supplement biomass; Option 2: Post-aerobic MBR membrane reactor, DO controlled at 2-4 mg / L, hydraulic retention time 2-4 h, hollow fiber membrane pore size 0.1-0.4 μm, thoroughly remove residual ammonia nitrogen, trace organic matter and suspended solids, effluent SS close to 0; MBR sludge return ratio 50%-95%, returned to hydrolysis acidification tank or short-cut nitrification reactor; Step S6. Stabilization and control of effluent recirculation A portion of the supernatant after deep purification is recycled to the pretreatment inlet, with a recycling rate of 20%-95%: 20%-40% for low-concentration inlet water and 50%-95% for high-concentration shock inlet water; this dilutes the high ammonia nitrogen inlet water concentration, buffers water quality and quantity fluctuations, reduces the inhibition of anaerobic ammonia-oxidizing bacteria by high nitrogen load, and ensures long-term stable operation of the system.

[0019] The present invention includes a second aspect, a system for performing the above-described high ammonia nitrogen wastewater denitrification treatment process based on anaerobic ammonia oxidation, comprising, in sequence along the water flow direction, a pretreatment unit, a short-cut nitrification reactor, a primary anaerobic ammonia oxidation reactor, an intermediate equalization tank, a secondary anaerobic ammonia oxidation reactor, and a deep purification unit, which are connected by pipelines in sequence. The pretreatment unit includes a bar screen, a primary sedimentation tank, an air flotation oil removal device, a pH adjustment tank, and a hydrolysis acidification tank connected in series; the intermediate adjustment tank is equipped with a raw water inlet pipe and a primary anaerobic ammonia oxidation effluent inlet pipe; the deep purification unit is equipped with a product water pipe, a sludge return pipe, and an effluent return pipe; all biochemical reactors are equipped with online pH detection, DO detection, temperature monitoring, and constant temperature control devices; the two-stage anaerobic ammonia oxidation reactors are equipped with a three-phase separator.

[0020] Example 1: Treatment of High Ammonia Nitrogen Wastewater from a Chemical Plant Influent water quality: ammonia nitrogen 1200-1500 mg / L, COD 100-150 mg / L, with large fluctuations in water quality.

[0021] The wastewater treatment steps are as follows: S1 Preprocessing High ammonia nitrogen wastewater is sequentially treated by screen slag removal, primary sedimentation, and air flotation to remove suspended solids and grease. Chemical plant wastewater is prone to heavy metal contamination, so coagulation and sedimentation treatment is added. 40 mg / L PAC and 3 mg / L PAM are added to the coagulation and sedimentation tank, stirred for 18 min, and settled for 35 min. The wastewater is then sent to a pH adjustment tank to adjust the pH to 7.7, and then enters a hydrolysis acidification tank for 9 h of reaction to hydrolyze large molecular organic matter. S2 Short-cut Nitrification The hydrolysis and acidification effluent enters the short-cut nitrification reactor, with DO controlled at 0.5 mg / L, temperature at 30℃, pH at 7.7, and hydraulic retention time at 5 h; the ammonia nitrogen oxidation rate is controlled at 55%, the sludge age at 9 days, and the molar ratio of nitrite to ammonia nitrogen in the effluent is 1.2:1. S3 Primary Anaerobic Ammonium Oxidation The effluent from the short-cut nitrification process enters the primary anaerobic ammonium oxidation reactor, which is filled with a composite sludge system: anaerobic ammonium oxidation granular sludge combined with a biological carrier, with a volume ratio of 2:1; the anaerobic ammonium oxidation granular sludge has a particle size of 1.0-2.0 mm and an MLSS of 8000 mg / L; the biological carrier is a hollow suspended packing material and biological rope with a specific surface area of ​​1200 m² / m³. Process parameter control: temperature 30℃, pH 7.8, hydraulic retention time 10h, influent ammonia nitrogen load 0.6kgN / (m³・d), light-proof and oxygen-deficient environment; S4 secondary combined with denitrification The effluent from the primary anaerobic ammonia oxidation process is sent to an intermediate equalization tank and mixed with a portion of the raw water at a volume ratio of 4:1. The organic matter in the raw water is used to reduce nitrates to nitrites. The mixture then enters the secondary anaerobic ammonia oxidation reactor, where the remaining ammonia nitrogen and regenerated nitrites undergo another anaerobic ammonia oxidation reaction. The process parameters are controlled as follows: temperature 30℃, pH 7.8, hydraulic retention time 6h, DO < 0.15mg / L. S5 Deep Purification The effluent from the secondary anammox reactor is sent to a sulfur autotrophic denitrification sedimentation tank. After sludge-water separation, part of the settled sludge is returned to the primary anammox reactor at a return ratio of 30%. S6 Reflux Control 30% of the supernatant after deep purification is returned to the pretreatment inlet to dilute the ammonia nitrogen in the inlet water and buffer fluctuations in water quality and quantity. The remaining effluent is discharged in compliance with standards.

[0022] After 6 months of continuous operation, the test results are as follows: effluent ammonia nitrogen ≤14mg / L, total nitrogen removal rate 96.2%; no external carbon source was added, aeration energy consumption was reduced by 48% compared with traditional process, and the system had no fluctuation in denitrification efficiency.

[0023] Example 2: Late-stage leachate treatment at landfills Influent water quality: ammonia nitrogen 1600-1900 mg / L, COD 150-200 mg / L; The wastewater treatment steps are as follows: S1 Preprocessing High ammonia nitrogen wastewater is sequentially treated by screen slag removal, primary sedimentation, and air flotation to remove suspended solids and grease. Based on the heavy metal content in the leachate wastewater, coagulation sedimentation treatment is added. PAC 50mg / L and PAM 5mg / L (adjusted according to heavy metal content) are added to the coagulation sedimentation tank, stirred for 20 minutes, and settled for 40 minutes. The wastewater is then sent to a pH adjustment tank to adjust the pH to 7.5, and then enters a hydrolysis acidification tank for 10 hours to hydrolyze large molecular organic matter. S2 Short-cut Nitrification The hydrolysis and acidification effluent enters the short-cut nitrification reactor, with DO controlled at 0.6 mg / L, temperature at 30℃, pH at 7.5, and hydraulic retention time at 6 h; the ammonia nitrogen oxidation rate is controlled at 58%, the sludge age at 9 days, and the molar ratio of nitrite to ammonia nitrogen in the effluent is 1.3:1. S3 Primary Anaerobic Ammonium Oxidation The effluent from the short-cut nitrification process enters the primary anaerobic ammonium oxidation reactor, which is filled with a composite sludge system: anaerobic ammonium oxidation granular sludge combined with a biological carrier, with a volume ratio of 3:1; the anaerobic ammonium oxidation granular sludge has a particle size of 1.5-2.0 mm and an MLSS of 10000 mg / L, and the biological carrier is a hollow suspended packing with a specific surface area of ​​1500 m² / m³. Process parameter control: temperature 30℃, pH 7.6, hydraulic retention time 12h, influent ammonia nitrogen load 0.5kgN / (m³・d), light-proof and oxygen-deficient environment; S4 secondary combined with denitrification The effluent from the primary anaerobic ammonia oxidation process is sent to an intermediate equalization tank and mixed with a portion of the raw water at a volume ratio of 4:1. The organic matter in the raw water is used to reduce nitrates to nitrites. The mixture then enters the secondary anaerobic ammonia oxidation reactor, where the remaining ammonia nitrogen and regenerated nitrites undergo another anaerobic ammonia oxidation reaction. The process parameters are controlled as follows: temperature 30℃, pH 7.6, hydraulic retention time 6h, DO < 0.20mg / L. S5 Deep Purification The effluent from the secondary anaerobic ammonia oxidation was sent to the subsequent aerobic MBR membrane reactor. The DO was controlled at 3 mg / L, the hydraulic retention time was 3 h, the hollow fiber membrane pore size was 0.2 μm, and the effluent SS was close to 0. The MBR sludge return ratio is 60%, and the sludge is returned to the hydrolysis acidification tank and the short-cut nitrification reactor. S6 Reflux Control 40% of the supernatant after deep purification is returned to the pretreatment inlet to dilute the ammonia nitrogen in the inlet water and buffer fluctuations in water quality and quantity. The remaining effluent is discharged in compliance with standards.

[0024] After three months of continuous operation, the test results are as follows: the total nitrogen removal rate is 95.1%, and the effluent ammonia nitrogen and total nitrogen both meet the "Pollution Control Standard for Municipal Solid Waste Landfills" and can withstand a 30% influent ammonia nitrogen concentration shock load.

[0025] Comparative Example 1: Traditional Nitrification-Denitrification Process In Example 1, the same quality chemical wastewater was treated using a traditional process with continuous addition of sodium acetate as a carbon source. After 6 months of continuous operation, the test results were as follows: the aeration energy consumption was 54% higher than that of Example 1, the sludge production was 46% higher than that of Example 1, the total nitrogen removal rate was only 82%-88%, the denitrification efficiency dropped significantly when the influent load fluctuated, and the overall operating cost was about twice that of the process cost of this invention.

[0026] The above are merely embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A high-ammonia nitrogen wastewater denitrification treatment process based on anaerobic ammonia oxidation, characterized in that, Includes the following steps: Step S1. Preprocessing High ammonia nitrogen wastewater is sequentially processed through a screen for slag removal, primary sedimentation, and air flotation for oil removal to remove suspended solids and grease. It is then sent to a pH adjustment tank to adjust the pH to 7.2-8.0, and then enters a hydrolysis acidification tank to hydrolyze large molecular organic matter and reduce organic inhibition. Step S2. Short-cut nitrification The hydrolyzed and acidified effluent enters a short-cut nitrification reactor, where DO is controlled at 0.3-1.0 mg / L, temperature at 30-35℃, pH at 7.5-8.0, and hydraulic retention time at 4-8 h. The ammonia nitrogen oxidation rate is controlled at 50%-60%, resulting in a nitrite to ammonia nitrogen molar ratio of 1.0-1.3:1 in the effluent. Nitrite-oxidizing bacteria are inhibited by controlling free ammonia at 0.1-1.0 mg / L. Step S3. Primary anaerobic ammonium oxidation for denitrification The short-cut nitrification effluent enters the primary anaerobic ammonium oxidation reactor, which is filled with a composite sludge system of anaerobic ammonium oxidation granular sludge and biological carrier. Under anaerobic and light-proof conditions, the denitrification reaction of ammonia nitrogen and nitrite is completed, generating nitrogen gas and nitrate. Step S4. Secondary anaerobic ammonium oxidation combined with short-cut denitrification The effluent from the primary anaerobic ammonia oxidation is sent to the intermediate equalization tank and mixed with some raw water at a volume ratio of 3:1-5:

1. The organic matter in the raw water is used to reduce nitrate to nitrite. The mixture enters the secondary anaerobic ammonia oxidation reactor, where the remaining ammonia nitrogen and regenerated nitrite undergo anaerobic ammonia oxidation again. Step S5. Deep purification and mud-water separation The effluent from the secondary anammox reactor is sent to a deep purification unit to remove residual nitrate nitrogen and suspended solids. After sludge-water separation, part of the settled sludge is returned to the primary anammox reactor at a return ratio of 20%-40%. Step S6. Reflux stabilization control The supernatant after deep purification is returned to the pretreatment inlet at a rate of 20%-95% to dilute the ammonia nitrogen in the inlet water and buffer fluctuations in water quality and quantity. The remaining effluent is discharged in compliance with standards.

2. The high-ammonia nitrogen wastewater denitrification treatment process based on anaerobic ammonia oxidation according to claim 1, characterized in that, In step S1, the hydraulic retention time in the hydrolysis acidification tank is 6-12 hours, and the tank is filled with 30%-50% combined packing material. For the pretreatment of wastewater with high suspended solids and heavy metals, a coagulation and sedimentation process is added, with 30-50 mg / L of polyaluminum chloride and 2-5 mg / L of polyacrylamide added, the mixture is stirred for 15-20 minutes, and the sediment is allowed to stand for 30-40 minutes.

3. The high-ammonia nitrogen wastewater denitrification process based on anaerobic ammonia oxidation according to claim 1, characterized in that, In step S2, the short-cut nitrification reactor is a sequencing batch reactor or a continuous flow reactor, with a microporous aeration device and a stirring device installed at the bottom; the concentration of nitrified sludge in the reactor is 3000-4000 mg / L, and the sludge age is controlled at 8-10 days.

4. The high-ammonia nitrogen wastewater denitrification treatment process based on anaerobic ammonia oxidation according to claim 1, characterized in that, In step S3, the volume ratio of anaerobic ammonia oxidation granular sludge to biological carrier in the composite sludge system is 2:1-3:1; the granular sludge particle size is 0.5-3.0 mm, and the MLSS is 5000-10000 mg / L; the biological carrier is selected from one or more of polyurethane foam, hollow suspended packing, and biological rope, with a specific surface area of ​​500-2000 m³ / m²; the temperature of the primary anaerobic ammonia oxidation reactor is controlled at 30-35℃, pH at 7.0-8.0, and hydraulic retention time at 6-12 h, with an influent ammonia nitrogen load ≤1.5 kgN / (m³・d).

5. The high-ammonia nitrogen wastewater denitrification process based on anaerobic ammonia oxidation according to claim 1, characterized in that, In step S4, the secondary anaerobic ammonia oxidation reactor is filled with 20%-40% anaerobic ammonia oxidation biofilm packing material, the dissolved oxygen is controlled to be <0.2mg / L, and the hydraulic retention time is 4-8h.

6. The high-ammonia nitrogen wastewater denitrification process based on anaerobic ammonia oxidation according to claim 1, characterized in that, In step S5, the deep purification unit is a sedimentation tank with built-in sulfur autotrophic denitrification packing, which relies on sulfur autotrophic bacteria to remove residual nitrates.

7. The high-ammonia nitrogen wastewater denitrification process based on anaerobic ammonia oxidation according to claim 1, characterized in that, In step S5, the deep purification unit is a post-aerobic MBR membrane reactor, with DO controlled at 2-4 mg / L, hydraulic retention time at 2-4 h, hollow fiber membrane pore size at 0.1-0.4 μm, MBR sludge return ratio at 50%-95%, and sludge returned to the hydrolysis acidification tank or short-cut nitrification reactor.

8. The high-ammonia nitrogen wastewater denitrification process based on anaerobic ammonia oxidation according to claim 1, characterized in that, In step S6, the recirculation ratio is adjusted according to the influent ammonia nitrogen concentration: 20%-40% recirculation for low-load influent and 50%-95% recirculation for high-impact load influent.

9. The high-ammonia nitrogen wastewater denitrification process based on anaerobic ammonia oxidation according to claim 1, characterized in that, The entire process is equipped with a PLC intelligent control system, which monitors and automatically adjusts dissolved oxygen concentration, temperature, pH value, hydraulic retention time, and effluent recirculation ratio online to achieve automated and stable operation.

10. A treatment system for high-ammonia nitrogen wastewater denitrification based on any one of claims 1-9, characterized in that, It includes the following components connected sequentially by pipes along the water flow direction: a pretreatment unit, a short-cut nitrification reactor, a primary anaerobic ammonium oxidation reactor, an intermediate equalization tank, a secondary anaerobic ammonium oxidation reactor, and a deep purification unit; The pretreatment unit includes a bar screen, a primary sedimentation tank, an air flotation oil removal device, a pH adjustment tank, and a hydrolysis acidification tank connected in series. The intermediate adjustment tank is equipped with a raw water inlet pipe and a primary anaerobic ammonia oxidation effluent inlet pipe. The deep purification unit is equipped with a product water pipe, a sludge return pipe, and an effluent return pipe. All biochemical reactors are equipped with online pH monitoring, DO monitoring, temperature monitoring, and constant temperature control devices. The two-stage anaerobic ammonia oxidation reactors are equipped with a three-phase separator.