Method for treating coal chemical high ammonia-nitrogen wastewater based on Canon-A / O process of anaerobic ammonia oxidation

Abstract

The present application relates to the technical field of industrial wastewater treatment, in particular to a method for treating coal chemical high ammonia-nitrogen wastewater based on Canon-A / O process of anaerobic ammonia oxidation, which takes Canon reaction tank as the main denitrification unit and bears most of the ammonia-nitrogen removal load, and takes A / O biochemical tank as the subsequent guarantee unit to deeply purify residual nitrogen, and the two units work together to realize the cascade denitrification and deep treatment of high ammonia-nitrogen wastewater. The method provided by the present application can stably achieve more than 95% of the overall removal rate of ammonia-nitrogen and more than 90% of the removal rate of total nitrogen.

Description

Technical Field

[0001] This invention relates to the technical field of industrial wastewater treatment, specifically a method for treating high ammonia nitrogen wastewater from coal chemical industry based on the Canon-A / O process of anaerobic ammonia oxidation. Background Technology

[0002] As a crucial component of the national energy strategy, the coal chemical industry generates substantial amounts of wastewater with complex compositions and extremely high pollutant concentrations during its coal gasification, liquefaction, coking, and ammonia synthesis processes. Among these, high-ammonia-nitrogen wastewater presents a significant challenge in its treatment. This type of wastewater typically exhibits the following characteristics: extremely high ammonia-nitrogen concentrations (usually 300-1000 mg / L, and sometimes exceeding 2000 mg / L); severely imbalanced carbon-to-nitrogen ratios (COD / TN often below 3:1, or even less than 1:1); the presence of persistent toxic organic compounds such as phenols, cyanides, and polycyclic aromatic hydrocarbons; and significant fluctuations in water quality and quantity. Direct discharge of this type of wastewater without proper treatment will lead to eutrophication of receiving water bodies, posing a major threat to the ecological environment and human health.

[0003] Currently, the industry mainly adopts a process route of "pretreatment + biological treatment + advanced treatment" for the treatment of high ammonia nitrogen wastewater from coal chemical industry. In the core biological treatment unit, traditional methods generally rely on the nitrification-denitrification principle. The nitrification process, under aerobic conditions, reduces ammonia nitrogen (NH4+) to nitrogen. + -N) is oxidized to nitrite (NO2) - -N) and nitrates (NO3) - The denitrification process, under anaerobic conditions, utilizes an organic carbon source to reduce nitrate nitrogen to nitrogen gas (N2). However, directly applying this traditional process to high-ammonia-nitrogen wastewater from coal chemical plants reveals numerous insurmountable technical bottlenecks and economic problems: Severe carbon source shortage and high cost: Denitrification requires a sufficient organic carbon source as an electron donor. Theoretically, reducing 1g of nitrate nitrogen (in the form of NO3-) requires a significant amount of organic carbon. - The required COD (BOD) is approximately 2.86g (based on nitrogen content), but the actual requirement is higher due to efficiency issues. The inherently low carbon-to-nitrogen ratio of coal chemical wastewater means that the endogenous carbon sources in the influent are far from sufficient to meet the needs of complete denitrification. Therefore, a large amount of exogenous carbon sources, such as methanol, sodium acetate, and glucose, must be added. This not only makes reagent costs a major part of operating expenses (up to 40%-60%), but also increases the risk of subsequent COD (chemical oxygen demand) exceeding standards and sludge production.

[0004] Aeration consumes a huge amount of energy: Traditional full-process nitrification requires the complete oxidation of ammonia nitrogen to nitrate, a process that consumes a large amount of oxygen. Oxidation of 1g of NH4... + -N to NO3 -The theoretical oxygen demand for ammonia nitrogen (N) is 4.57 g O2. For wastewater with ammonia nitrogen concentrations as high as several hundred mg / L, the electricity consumption required for aeration is extremely considerable, making it a major energy-consuming unit in wastewater treatment plants.

[0005] Alkalinity consumption and pH regulation are complex: nitration is an acid-producing process, and for every 1g of NH4 oxidized... + -N will consume approximately 7.14g of alkalinity (calculated as CaCO3). Nitrification of high-ammonia nitrogen wastewater causes a sharp drop in system pH. If alkalinity is not replenished in time (e.g., by adding NaOH, Na2CO3, lime, etc.), the activity of nitrifying bacteria will be severely inhibited or even destroyed. Adding alkalinity further increases operating costs and complexity.

[0006] Large sludge production and high disposal costs: Heterotrophic denitrifying bacteria grow rapidly, and traditional processes generate a large amount of excess sludge. Sludge treatment (concentration, dewatering, drying, and disposal) is expensive and faces increasingly stringent environmental regulations.

[0007] The process is lengthy, requires a large footprint, and has weak resistance to shock loads: To achieve deep denitrification, complex processes such as multi-stage A / O and post-denitrification are often required, which prolongs the hydraulic retention time (HRT), increases infrastructure investment, and requires more land. At the same time, the system is sensitive to changes in influent water quality, quantity, and temperature, has insufficient resistance to shock loads, and the effluent water quality is difficult to consistently meet standards.

[0008] To address these challenges, the sequencing batch reactor (SBR) has been applied to the treatment of high ammonia nitrogen wastewater due to its operational flexibility and ability to achieve temporal and spatial alternation between anoxic and aerobic processes within a single reactor. However, the SBR process is essentially still within the framework of traditional nitrification and denitrification, and issues such as carbon source requirements, high energy consumption, and alkalinity depletion persist. Furthermore, its treatment efficiency and stability face challenges when dealing with ultra-high concentrations of ammonia nitrogen shocks.

[0009] In recent years, anammox, as a revolutionary autotrophic biological nitrogen removal technology, has received widespread attention. Anammox bacteria, under anoxic or anaerobic conditions, utilize nitrite (NO2) to produce nitrogen. - -N) acts as an electron acceptor, directly transferring ammonia nitrogen (NH4) + NH4+ is converted into nitrogen gas (N2) in the process, while a small amount of nitrate is produced. The simplified chemical formula is: NH4+ + NH4+. + + 1.32NO2 - →1.02N2+ 0.26NO3 -+ 2H2O. This technology boasts disruptive advantages such as requiring no organic carbon source, saving approximately 60% on aeration energy consumption, extremely low sludge production, and reducing greenhouse gas emissions. Based on this, the CANON (Completely Autotrophic Nitrogenremoval Over Nitrite) process is developed in a single reactor or biofilm system. By controlling low dissolved oxygen, ammonia-oxidizing bacteria (AOB) oxidize some ammonia nitrogen to nitrite, which is then coupled by anaerobic ammonia-oxidizing bacteria (AnAOB) to achieve fully autotrophic denitrification.

[0010] However, applying the pure Canon process directly to complex industrial wastewater, especially coal chemical wastewater, still faces significant challenges: AnAOB grows slowly (doubling time is about 10-14 days), making start-up and acclimatization difficult; it is extremely sensitive to water quality conditions (such as dissolved oxygen, pH, matrix concentration, and inhibitors); when the influent ammonia nitrogen concentration is extremely high, a single Canon reactor cannot achieve complete conversion of ammonia nitrogen, and the effluent still retains a certain concentration of ammonia nitrogen and nitrate nitrogen, which cannot meet the strict discharge standards.

[0011] Therefore, the key to solving the problem of treating high ammonia nitrogen wastewater from coal chemical industry lies in combining the high efficiency and energy-saving advantages of anaerobic ammonia oxidation technology with the stable and reliable characteristics of traditional processes to develop an integrated process that is highly adaptable, thoroughly denitrifies, and has low operating costs. Summary of the Invention

[0012] In view of the problems existing in the prior art, the present invention provides a method for treating high ammonia nitrogen wastewater from coal chemical industry based on the Canon-A / O process of anaerobic ammonia oxidation.

[0013] The technical solution of this invention to solve the above-mentioned technical problems is as follows: A method for treating high ammonia nitrogen wastewater from coal chemical industry based on the Canon-A / O process of anaerobic ammonia oxidation, comprising the following steps: S101. Construct a treatment system, inoculate the Canon reactor with a composite strain containing anaerobic ammonia oxidizing bacteria and ammonia oxidizing bacteria, control the dissolved oxygen, pH and temperature in the Canon reactor, and acclimatize the bacteria. S102. The high ammonia nitrogen wastewater from coal chemical industry is introduced into the equalization tank for water quality homogenization, and then pumped into the Canon reaction tank to control dissolved oxygen, pH, temperature and hydraulic retention time. S103. The coal chemical high ammonia nitrogen wastewater treated in step S102 is flowed into the first sedimentation tank for solid-liquid separation, and the supernatant and sludge are separated. S104. The supernatant from step S103 is fed into the A / O biological treatment tank for denitrification and nitrogen removal. The dissolved oxygen, hydraulic retention time, and mixed liquor reflux ratio are controlled in the aerobic and anoxic sections, respectively. S105. The coal chemical high ammonia nitrogen wastewater treated in step S104 is flowed into the second sedimentation tank for sludge-water separation. Part of the sludge is returned to the first end of the anoxic section of the A / O biological treatment tank, and the water is discharged as the final effluent.

[0014] 2. The method for treating high ammonia nitrogen wastewater from coal chemical industry using the Canon-A / O process based on anaerobic ammonia oxidation according to claim 1, characterized in that, in step S101, the dissolved oxygen in the Canon reactor is controlled at 0.2-0.5 mg / L, the pH at 7.5-8.2, the temperature at 30-35℃, and the acclimatization period is 60-120 days.

[0015] 3. The method for treating high ammonia nitrogen wastewater from coal chemical industry based on the Canon-A / O process of anaerobic ammonia oxidation according to claim 1, characterized in that, in step S102, the dissolved oxygen is controlled at 0.2-0.5 mg / L, the pH is controlled at 7.5-8.2, the temperature is controlled at 30-38℃, and the hydraulic retention time is controlled at 1-5 days.

[0016] Furthermore, in step S104, the dissolved oxygen in the aerobic zone is controlled to be 1.5-3.0 mg / L, the dissolved oxygen in the anoxic zone is less than 0.5 mg / L, the hydraulic retention time is 12-36 hours, and the mixed liquor reflux ratio is 100%-300%.

[0017] The invention also provides a system for treating high ammonia nitrogen wastewater from coal chemical industry based on the Canon-A / O process of anaerobic ammonia oxidation. The system includes an equalization tank, a Canon reaction tank, a first sedimentation tank, an A / O biochemical tank, and a second sedimentation tank.

[0018] Furthermore, the Canon reaction tank includes a Canon reactor and a Canon sedimentation tank.

[0019] Furthermore, the A / O biological treatment tank includes an anoxic section and an aerobic section, and the volume ratio of the anoxic section to the aerobic section is 1:(2-3).

[0020] Furthermore, the system also includes a dosing system and a monitoring and control system. The dosing system is used to adjust the pH of the Canon reactor and to supplement the carbon source in the A / O anoxic biological tank.

[0021] Furthermore, the monitoring and control system includes one or more of the following: online pH meter, DO meter, thermometer, liquid flow meter, and air flow meter.

[0022] The beneficial effects of adopting the above-mentioned further solutions are as follows: The present invention provides a method for treating high ammonia nitrogen wastewater from coal chemical industry based on anaerobic ammonia oxidation using the Canon-A / O process. Employing a Canon-A / O coupled process, through functional zoning and process coupling, it fully leverages the advantages of both anaerobic ammonia oxidation technology and traditional A / O processes, generating a significant synergistic effect. Specific technical effects and beneficial effects are as follows: 1. High and thorough nitrogen removal efficiency: This system uses a Canon reactor as the "main" unit, efficiently removing most of the ammonia nitrogen with a high load rate; the A / O biological treatment tank serves as the "support" unit, deeply purifying residual nitrogen. The combination of these two units achieves cascaded denitrification and deep purification of high-ammonia nitrogen wastewater. Pilot-scale operation results show that the system provided by this invention maintains an overall ammonia nitrogen removal rate consistently above 95%, a total nitrogen removal rate consistently above 90%, and ultimately, the total nitrogen in the effluent remains consistently below 25 mg / L, even reaching below 15 mg / L.

[0023] 2. Significantly reduce operating costs: Regarding carbon source consumption, the Canon autotrophic denitrification process requires no organic carbon source at all, fundamentally reducing the main cost of carbon source consumption in the treatment of high ammonia nitrogen wastewater. The A / O biological treatment tank unit only needs to treat low concentrations of nitrate nitrogen, reducing the carbon source dosage by 60%-80% compared to traditional processes. In terms of energy consumption, the Canon process operates under microaerobic conditions, saving approximately 50%-60% of aeration energy compared to the full nitrification process of traditional wastewater treatment systems. Simultaneously, due to the lower treatment load of the A / O biological treatment tank unit, its aeration requirements are also significantly reduced. Regarding alkalinity... In terms of consumption, the Anammox reaction consumes less alkalinity and can partially offset the acid production during nitrification. Moreover, most of the ammonia nitrogen has been removed in the Canon reactor unit, which reduces the amount of acid produced by nitrification in the subsequent A / O biological treatment unit. Overall, alkalinity consumption is reduced by about 40%–60% compared to traditional processes. In terms of sludge production, AnAOB is an autotrophic microorganism with slow growth. The system operates with a long sludge age, resulting in extremely low overall sludge production. Compared to the traditional activated sludge process, sludge production can be reduced by 70%–90%, greatly reducing sludge treatment and disposal costs.

[0024] 3. Strong resistance to shock loads and stable operation: The biofilm or granular sludge system in the Canon reactor unit has high biomass and a stable microbial community structure, making it highly tolerant to water quality fluctuations; the A / O biological treatment unit acts as a "buffer" and "fine treatment," further balancing the impact of water quality fluctuations on the final effluent. The two-stage treatment structure enhances the overall stability of the system.

[0025] 4. Relatively space-saving: The high volumetric load of the Canon process makes its unit volume processing capacity far exceed that of traditional processes, shortening the total hydraulic retention time. When achieving the same treatment target, it can save about 20%-30% of the space compared with the traditional multi-stage A / O process.

[0026] 5. Relatively simple operation and management: The core control parameters of the system are clearly defined, such as DO and pH in the Canon tank; DO and carbon source addition in the A / O tank; combined with modern automated control technology, a high degree of automation and intelligent management can be achieved, thereby reducing the dependence on the experience of operators.

[0027] 6. Environmentally friendly: The wastewater treatment method provided by this invention reduces carbon source and energy consumption, reduces carbon dioxide emissions at the source, and also reduces the risk of secondary environmental pollution caused by sludge disposal due to the low sludge production, thus having good environmental benefits. Attached Figure Description

[0028] Figure 1 The present invention provides a process flow diagram of a method for treating high ammonia nitrogen wastewater from coal chemical industry based on the Canon-A / O process of anaerobic ammonia oxidation. Figure 2 This is a connection block diagram of a system for treating high ammonia nitrogen wastewater from coal chemical industry based on the Canon-A / O process of anaerobic ammonia oxidation, provided by the present invention. Figure 3 This is a diagram showing the ammonia nitrogen removal effect of the Canon reactor unit during 60 days of this invention; Figure 4 This is a graph showing the change in total nitrogen in the system effluent over a 60-day period according to the present invention. Figure 5 This is a diagram showing the ammonia nitrogen removal effect of the Canon reactor unit during the pilot-scale test in the experimental example of this invention. Figure 6 This is a graph showing the change in total nitrogen in the system effluent during the pilot-scale test in the experimental examples of this invention; Figure 7 This is a diagram showing the COD removal effect of the system during the pilot-scale test in the experimental example of this invention. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0030] Reference Appendix Figure 1-7This invention provides a method for treating high ammonia nitrogen wastewater from coal chemical industry using the Canon-A / O process based on anaerobic ammonia oxidation.

[0031] Example This invention provides a system for treating high ammonia nitrogen wastewater from coal chemical industry based on the Canon-A / O process of anaerobic ammonia oxidation. The system includes, in sequence along the water flow direction, an equalization tank, a Canon reaction tank, a first sedimentation tank, an A / O biochemical tank, and a second sedimentation tank.

[0032] Specifically, the equalization tank is made of PE material and is used to store and homogenize high ammonia nitrogen wastewater from the site; The Canon reactor comprises a Canon reactor and a Canon sedimentation tank. The Canon reactor is a cylindrical, corrosion-resistant carbon steel structure. A certain proportion of bio-rope packing material is added to the reactor as a carrier for enriching and immobilizing anaerobic ammonia-oxidizing bacteria and ammonia-oxidizing bacteria. This carrier can be one or more of self-suspended packing, fixed packing, or granular sludge beds. The self-suspended packing material can be MBBR packing. An aeration membrane pipe is installed at the bottom, and the aeration rate is controlled by a rotor flow meter and an online DO meter. The Canon sedimentation tank is made of corrosion-resistant carbon steel and is used to separate and recirculate Canon sludge. The first sedimentation tank is a corrosion-resistant carbon steel structure, measuring 2m × 2m × 3.5m, used for the separation and return of Canon sludge. The A / O biological treatment tank is a rectangular carbon steel corrosion-resistant device with a partition in the middle dividing it into anoxic and aerobic sections with a volume ratio of 1:(2-3). The aerobic section is equipped with aeration pipes.

[0033] The second sedimentation tank is made of PE material and is used for the final separation of mud and water.

[0034] This invention provides a method for treating high ammonia nitrogen wastewater from coal chemical industry using the Canon-A / O process based on anaerobic ammonia oxidation, comprising: S101. Construct a treatment system, inoculate the Canon reactor with a composite strain containing anaerobic ammonia oxidizing bacteria and ammonia oxidizing bacteria, control dissolved oxygen, pH and temperature, and acclimatize the bacteria. Specifically, the treatment system is constructed according to the aforementioned system structure. Then, a composite strain containing anaerobic ammonia oxidizing bacteria and ammonia-oxidizing bacteria is inoculated into the Canon reactor. This strain can be derived from a stably operating anaerobic ammonia oxidation project or pilot plant, laboratory-cultured granular sludge, or biofilm packing. During the initial start-up phase, simulated wastewater with a low ammonia nitrogen concentration, such as 200-300 mg / L, or diluted actual wastewater is used for cultivation. The influent ammonia nitrogen load and proportion are gradually increased. Dissolved oxygen in the reactor is controlled at a microaerobic environment of 0.2-0.5 mg / L, pH is maintained at 7.5-8.2, and temperature is kept at 30-35℃. The acclimatization period is generally 60-120 days, until the Canon reactor achieves an ammonia nitrogen removal rate of over 80% and operates stably.

[0035] S102. The high ammonia nitrogen wastewater from coal chemical industry is introduced into the equalization tank for water quality homogenization and then pumped into the Canon reaction tank to control dissolved oxygen, pH, temperature and hydraulic retention time. Specifically, the high-ammonia-nitrogen wastewater from the coal chemical industry, homogenized in the equalization tank, is pumped into the Canon reactor. In this reactor, aeration is precisely controlled using micro-aeration or intermittent aeration methods to maintain dissolved oxygen (DO) within the range of 0.2-0.5 mg / L. Under these microaerobic conditions, ammonia-oxidizing bacteria (AOBs) gain dominance in the outer aerobic layer of the biofilm or granular sludge, reducing some of the NH4+ in the influent. + -N is oxidized to NO2 - -N. The generated NO2 - -N diffuses into the anoxic inner layer of the biofilm or granular sludge, where it mixes with the remaining NH4+. + -N undergoes a coupling reaction catalyzed by anaerobic ammonia-oxidizing bacteria (AnAOB) to generate nitrogen gas. This process achieves autotrophic denitrification using ammonia nitrogen itself as an electron donor without the need for an external organic carbon source.

[0036] Control the dissolved oxygen (DO) level to 0.2-0.5 mg / L. If the DO level is too low, the activity of Anammox bacteria (AOB) will be insufficient, resulting in a shortage of nitrite nitrogen supply. If the DO level is too high, nitrite-oxidizing bacteria (NOB) will proliferate, oxidizing nitrite to nitrate, which will destroy the Anammox reaction matrix. Furthermore, dissolved oxygen penetrating into the biofilm will inhibit AnAOB.

[0037] The pH value is 7.5-8.2, and the alkalinity is adjusted by online monitoring and automatic addition of alkalinity using NaHCO3 and Na2CO3 solutions. Preferably, the pH value is 8.0. The temperature is 30-38℃; The HRT (Heat Retention Time) is 1-5 days, which can be determined based on the influent ammonia nitrogen concentration and the designed removal load. For example, for influent with ammonia nitrogen of 500 mg / L, the designed HRT is 2-3 days.

[0038] Sludge duration (SRT) is the period of time maintained by controlling sludge discharge (usually >30 days) to facilitate the retention and enrichment of slow-growing AnAOB.

[0039] S103. The wastewater treated in step S102 flows into the first sedimentation tank for solid-liquid separation. Most of the sludge containing highly active AnAOB and AOB that settles is returned to the Canon reactor at a return ratio of 50%-150% to maintain the biomass concentration and community stability in the reactor. A small amount is discharged as excess sludge, and the supernatant is the Canon effluent, which enters the next stage A / O biological treatment tank.

[0040] S104. The supernatant from step S103 is fed into the A / O biological tank for denitrification and nitrogen removal. The dissolved oxygen, hydraulic retention time, and mixed liquor reflux are controlled in the aerobic and anoxic sections, respectively. Specifically, the anoxic section (Section A): its main function is denitrification. The nitrate nitrogen (NO3) in the Canon effluent... - -N) and some nitrite nitrogen (NO2) - In this section, the biodegradable organic matter (endogenous carbon source) remaining in the Canon effluent is used as an electron donor and reduced to nitrogen by denitrifying bacteria. Since the nitrogen load has been significantly reduced after passing through the Canon unit, and the residual organic matter may be insufficient, a small amount of exogenous carbon source can be added to the anoxic section through the dosing system according to the total nitrogen target of the effluent.

[0041] The aerobic stage (O stage) primarily functions to completely nitrify residual ammonia nitrogen and further degrade residual organic matter. After the anoxic stage, the ammonia nitrogen concentration in the water is already low. Under sufficient dissolved oxygen (DO controlled at 1.5-3.0 mg / L), the aerobic stage utilizes nitrifying bacteria to oxidize the remaining ammonia nitrogen into nitrate nitrogen. This newly generated nitrate nitrogen can be recycled through the mixed liquor to the anoxic stage for denitrification, thus forming a denitrification cycle within the A / O system, further reducing total nitrogen.

[0042] Control DO in the anoxic phase to <0.5 mg / L, DO in the aerobic phase to 1.5-3.0 mg / L, total HRT to 12-36 hours, and mixed liquor reflux ratio to 100%-300%.

[0043] S105. The wastewater treated in step S104 flows into the second sedimentation tank for final sludge-water separation. A portion of the settled sludge is returned to the beginning of the anoxic section of the A / O biological treatment tank to maintain the system's sludge concentration. The treated water is discharged as the final effluent, and its COD, ammonia nitrogen, and total nitrogen levels should meet the predetermined discharge standards.

[0044] Performance testing A small-scale test was conducted in the laboratory to treat artificially prepared simulated wastewater using the Canon-A / O process based on anaerobic ammonia oxidation described in Example 1. This further verified the process's adaptability and parameter boundaries. The specific parameters of the pilot-scale apparatus are as follows: (1) The equalization tank is made of transparent PVC board with dimensions of 500mm × 400mm × 400mm (length × width × height); the effective volume is 60L; the bottom of the equalization tank is equipped with an air drain valve and the top is equipped with a stirring device to ensure uniform water quality.

[0045] (2) The Canon reactor is made of plexiglass, cylindrical in shape, with an inner diameter of 150 mm and a height of 800 mm; the effective volume is 12 L; the main body of the reactor has 5 sampling ports located at 100 mm, 250 mm, 400 mm, 550 mm and 700 mm from the bottom, respectively, for process water quality analysis. The top is equipped with a sealed cover, with vent holes, pH / DO probe insertion ports and water inlet ports. The bottom is equipped with microporous aeration discs with a diameter of 80 mm and a pore size of 0.2 mm; the reactor is filled with polyethylene K3 type MBBR packing (diameter 25 mm, height 10 mm, specific surface area > 500 m²). 2 / m 3 It has a filling rate of 40% (i.e., 4.8L) and is equipped with a 20mm thick water bath jacket for constant temperature control.

[0046] (3) The first sedimentation tank is made of plexiglass and is a vertical flow sedimentation tank; the dimensions are 150mm × 150mm × 300mm (length × width × height) and the effective volume is 5L; a guide tube (50mm in diameter and 200mm in height) is set in the center of the tank, a conical sludge hopper (60° cone angle) is set at the bottom, and the sludge return pipe has a diameter of 10mm; an annular overflow trough is set at the top for collecting the supernatant.

[0047] (4) The A / O reactor is made of plexiglass; it is rectangular in shape, with internal partitions dividing it into anoxic and aerobic zones; the total dimensions are 600mm × 200mm × 300mm (length × width × height), and the total effective volume is 30L, of which the anoxic zone has a volume of 10L and the aerobic zone has a volume of 20L; the anoxic zone is 200mm × 200mm × 300mm (length × width × height), and has a built-in mechanical stirrer with an adjustable speed of 0-200 rpm; the aerobic zone is 400mm × 200mm × 300mm (length × width × height), with microporous aeration pipes (10mm diameter, 0.2mm aperture) at the bottom; water passage holes (20mm aperture) at the bottom of the partition between the anoxic and aerobic zones; a nitrification liquid return port at the end of the aerobic zone, returning the liquid to the front of the anoxic zone; both zones are equipped with suspended packing material, with a filling rate of 30% (3L in the anoxic zone and 6L in the aerobic zone), and the packing material type is the same as that of the Canon reactor.

[0048] (5) The second sedimentation tank is made of plexiglass and is a vertical flow sedimentation tank; its dimensions are 150mm × 150mm × 250mm (length × width × height) and its effective volume is 4L.

[0049] Wastewater influent conditions settings Operating Condition A (Medium Concentration): Influent NH4 + -N was 300 mg / L, COD was 400 mg / L, and C / N ≈ 1.3. The HRT of the Canon reactor unit was controlled at 2 days, and DO was 0.3-0.5 mg / L.

[0050] The results are as follows Figure 3-4 As shown, Canon's effluent NH4 + -N<15 mg / L, TN (total nitrogen) about 50 mg / L; after treatment by the A / O unit (HRT=1.5 days), the final effluent TN<10 mg / L.

[0051] Operating Condition B (High Concentration): Influent NH4 + -N was 800 mg / L, COD was 600 mg / L, and C / N ≈ 0.75. The HRT of the Canon reactor unit was extended to 4 days, and DO was 0.5-0.7 mg / L. NH4 in the effluent of the Canon reactor unit + -N is approximately 50 mg / L, and TN is approximately 150 mg / L; The HRT of the A / O biological treatment tank unit was extended to 2.5 days, and the carbon source addition was appropriately increased, resulting in a final effluent TN < 20 mg / L.

[0052] The results show that the process of the present invention has good adaptability to high ammonia nitrogen wastewater with different ammonia nitrogen concentrations, and excellent denitrification effect can be achieved by adjusting key parameters such as HRT and DO of each unit.

[0053] Experimental Example According to Embodiment 1 of the present invention, a method and system for treating high ammonia nitrogen wastewater from coal chemical industry based on the Canon-A / O process of anaerobic ammonia oxidation was tested on-site at Jinju Chemical Industry.

[0054] 1. Construction of pilot-scale system The pilot-scale system was constructed according to the process route of this invention, and the main structures and equipment are as follows: Raw water tank: PE material, 8m³ capacity 3 It is used for storing and homogenizing high ammonia nitrogen wastewater from the site.

[0055] Canon reactor: The main body is a cylindrical carbon steel corrosion-resistant device, with dimensions of Ø2.8m × 6.5m and an effective volume of 35m³.3 ; Canon sedimentation tank: Corrosion resistant carbon steel, dimensions 2m×2m×3.5m; A / O biological treatment tank: Rectangular carbon steel corrosion-resistant equipment, dimensions 2m×6m×3m, effective volume approximately 28m³. 3 The volume ratio of the hypoxic section to the aerobic section is approximately 1:2. Final outlet water tank: made of PE material, with a volume of 5m³. 3 ; The dosing system includes an alkalinity dosing tank (for adding 25% NaOH solution to adjust the pH of the Canon tank) and a carbon source dosing tank (for adding sodium acetate solution to supplement the carbon source in the A / O anoxic zone).

[0056] Monitoring and control system: equipped with online pH meter, DO meter, thermometer, liquid flow meter and air flow meter.

[0057] 2. Wastewater quality and operational objectives Influent water quality: COD 350-650 mg / L, NH4 + -N is 450-550 mg / L, TN is 450-550 mg / L, pH is 8.3-8.8, and water temperature is 32-36℃.

[0058] Designed effluent water quality: Meets the company's internal control standards for reuse or advanced treatment, i.e., COD < 80 mg / L, NH4 < 10 mg / L. + -N < 15 mg / L, TN < 25 mg / L.

[0059] 3. System startup and acclimatization First, half the volume of a mixture of on-site wastewater and tap water was injected into the Canon reactor. After dilution, the ammonia nitrogen concentration was approximately 200 mg / L. Then, 2 mg / L of [agent / concentration] solution was added. 3 Anaerobic ammonia oxidation biofilm packing was used as seed sludge. During the initial start-up phase, intermittent influent and intermittent micro-aeration were employed, with dissolved oxygen (DO) strictly controlled below 0.2 mg / L, and pH maintained at 7.8-8.0 by automatic NaOH addition. Ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen levels were monitored daily. After 30 days, simultaneous removal of ammonia nitrogen and nitrite nitrogen was observed, along with the generation of nitrogen bubbles, indicating successful Anammox reaction startup. Subsequently, the influent ratio and ammonia nitrogen concentration were gradually increased until raw water was used entirely, and the aeration strategy was optimized to stabilize DO at 0.2-0.5 mg / L. The entire acclimation and enhancement period lasted 90 days, and the ammonia nitrogen removal load of the Canon unit reached 0.5 kgN / (m³). 3 ·d) and above.

[0060] 4. Parameters and Controls During Stable Operation The system has entered the stable operation phase of continuous flow, and the key operating parameters are controlled as follows: (1) Canon reactor: control the influent flow rate to 38-40 m³ / h 3 / d (HRT ≈ 0.88-0.92 days), DO is controlled at 0.2-0.5 mg / L via an aeration valve and an online DO meter; pH is controlled at 7.5-8.0 by automatic control of alkali addition via an online pH meter; temperature is controlled at 32-36℃ by utilizing the heat of the wastewater itself; sludge return ratio is 100%. (2) A / O biological treatment tank: The total HRT is 1.8-2.2 days. Preferably, the HRT of the anoxic section is 0.6 days and the HRT of the aerobic section is 1.4 days. The DO of the anoxic section is <0.3 mg / L and the DO of the aerobic section is 2.0-2.5 mg / L. The mixed liquor reflux ratio is 200%. According to the monitoring of nitrate nitrogen in the effluent of the aerobic section, sodium acetate solution is added intermittently to maintain the nitrate nitrogen in the effluent of the anoxic section <10 mg / L. The average dosage is equivalent to 20-30 mg / L of COD.

[0061] 5. Analysis of Operational Results (1) Denitrification effect: The results are as follows Figure 3-4 As shown, the Canon unit exhibited highly efficient and stable ammonia nitrogen removal performance during operation, with an average removal rate exceeding 98%. The influent ammonia nitrogen concentration was approximately 400-600 mg / L, which was reduced to single digits after treatment. Although the total nitrogen in the effluent from the Canon reactor still contained tens of milligrams per liter (mainly nitrate nitrogen), after advanced treatment by the A / O unit, the final average ammonia nitrogen removal rate was stably controlled within the range of 10-25 mg / L, far below the design effluent water quality target of less than 25 mg / L. Moreover, the total nitrogen content in the effluent remained below 15 mg / L for most of the time, and the overall total nitrogen removal rate of the system remained stable at 95%-98%, indicating that the combined process has good denitrification stability and treatment efficiency.

[0062] (2) COD removal: Results are attached. Figure 5 As shown, the influent COD fluctuated significantly, ranging from 250 to 650 mg / L. The Canon reactor achieved autotrophic denitrification while also removing approximately 20%-40% of COD. This phenomenon is mainly attributed to the synergistic metabolic effect of heterotrophic microorganisms on easily degradable organic matter. Further degradation of remaining organic matter by the A / O unit resulted in a final effluent COD stable at 50-120 mg / L, averaging below the design effluent quality target of 80 mg / L.

[0063] Compared with the traditional "multi-stage A / O + large amount of carbon source" scheme, the system provided by this invention has significant advantages in terms of operating costs: In terms of carbon source consumption, only a trace amount of carbon source is added in the A / O stage, reducing the carbon source cost per ton of water by about 75%; in terms of energy consumption, the Canon unit adopts low DO operation, reducing the aeration power consumption per ton of water by about 55%; in terms of alkalinity consumption, the alkalinity addition amount per ton of water (calculated as NaOH) is reduced by about 50%; in terms of sludge production, the system's residual sludge production is only about 20% of that of the traditional process, significantly reducing the burden of sludge treatment and disposal.

[0064] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for treating high-ammonia nitrogen wastewater from coal chemical industry using the Canon-A / O process based on anaerobic ammonia oxidation, characterized in that, Includes the following steps: S101. Construct a treatment system, inoculate the Canon reactor with a composite strain containing anaerobic ammonia oxidizing bacteria and ammonia oxidizing bacteria, control the dissolved oxygen, pH and temperature in the Canon reactor, and acclimatize the bacteria. S102. The high ammonia nitrogen wastewater from coal chemical industry is introduced into the equalization tank for water quality homogenization, and then pumped into the Canon reaction tank to control dissolved oxygen, pH, temperature and hydraulic retention time. S103. The coal chemical high ammonia nitrogen wastewater treated in step S102 is flowed into the first sedimentation tank for solid-liquid separation, and the supernatant and sludge are separated. S104. The supernatant from step S103 is fed into the A / O biological treatment tank for denitrification and nitrogen removal. The dissolved oxygen, hydraulic retention time, and mixed liquor reflux ratio are controlled in the aerobic and anoxic sections, respectively. S105. The coal chemical high ammonia nitrogen wastewater treated in step S104 is flowed into the second sedimentation tank for sludge-water separation. Part of the sludge is returned to the first end of the anoxic section of the A / O biological treatment tank, and the water is discharged as the final effluent.

2. The method for treating high ammonia nitrogen wastewater from coal chemical industry based on the Canon-A / O process of anaerobic ammonia oxidation according to claim 1, characterized in that, In step S101, the dissolved oxygen in the Canon reactor is controlled at 0.2-0.5 mg / L, the pH at 7.5-8.2, the temperature at 30-35℃, and the acclimatization period is 60-120 days.

3. The method for treating high ammonia nitrogen wastewater from coal chemical industry based on the Canon-A / O process of anaerobic ammonia oxidation according to claim 1, characterized in that, In step S102, the dissolved oxygen is controlled at 0.2-0.5 mg / L, the pH at 7.5-8.2, the temperature at 30-38℃, and the hydraulic retention time at 1-5 days.

4. The method for treating high ammonia nitrogen wastewater from coal chemical industry based on the Canon-A / O process of anaerobic ammonia oxidation according to claim 1, characterized in that, In step S104, the dissolved oxygen in the aerobic zone is controlled to be 1.5-3.0 mg / L, the dissolved oxygen in the anoxic zone is less than 0.5 mg / L, the hydraulic retention time is 12-36 hours, and the mixed liquor reflux ratio is 100%-300%.

5. A system for treating high-ammonia nitrogen wastewater from coal chemical industry using the Canon-A / O process based on anaerobic ammonia oxidation, characterized in that, The system includes an equalization tank, a Canon reaction tank, a first sedimentation tank, an A / O biochemical tank, and a second sedimentation tank.

6. The system for treating high ammonia nitrogen wastewater from coal chemical industry based on the Canon-A / O process of anaerobic ammonia oxidation according to claim 5, characterized in that, The Canon reaction tank includes a Canon reactor and a Canon sedimentation tank.

7. A system for treating high-ammonia nitrogen wastewater from coal chemical industry based on the Canon-A / O process of anaerobic ammonia oxidation according to claim 5, characterized in that, The A / O biological treatment tank includes an anoxic section and an aerobic section, and the volume ratio of the anoxic section to the aerobic section is 1:(2-3).

8. A system for treating high-ammonia nitrogen wastewater from coal chemical industry based on the Canon-A / O process of anaerobic ammonia oxidation according to claim 5, characterized in that, The system also includes a dosing system and a monitoring and control system. The dosing system is used to adjust the pH in the Canon reactor and to supplement the carbon source in the A / O anoxic biological tank.

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