Integrated treatment and reuse process and equipment for high organic nitrogen wastewater of chemical fiber

Abstract

The present application relates to the technical field of sewage treatment, and relates to an integrated treatment and reuse process and equipment for high organic nitrogen wastewater in the chemical fiber industry, which solves the problem of poor treatment effect in the prior art and provides an integrated treatment and reuse equipment for high organic nitrogen wastewater in the chemical fiber industry, which is integrated in one or more containers and comprises a conditioning tank, a demulsification and coagulation air flotation unit, a gradient anaerobic reactor, an overlapping biological denitrification reactor, a non-aeration MBR membrane system, an RO reverse osmosis system and a virtual intelligent expert algorithm system which are sequentially and communicatively arranged. The present application also provides an integrated treatment and reuse process for high organic nitrogen wastewater in the chemical fiber industry. The present application has the beneficial effects of high integration degree, high anaerobic ammonification efficiency, good denitrification effect, low energy consumption, greatly reduced MBR operation energy consumption, short process, no secondary pollution, full-automatic intelligent operation and the like.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment and reuse technology, and more specifically, to an integrated treatment and reuse process and equipment for high organic nitrogen wastewater from the chemical fiber industry. Background Technology

[0002] The chemical fiber industry is a core industry in my country's manufacturing sector. Wastewater from the production of spandex, nylon, aramid, and other chemical fiber products is typically high in organic nitrogen, with organic nitrogen accounting for ≥80% of total nitrogen. It also exhibits high COD concentrations, low B / C ratios, and contains bioinhibitory substances such as emulsified spinning oils. Therefore, achieving efficient nitrogen removal, low-energy treatment, and resource recovery for this type of wastewater is a core requirement for the industry.

[0003] The existing technology has the following shortcomings: (i) Low integration: Each functional processing unit is arranged as an independent component, which requires on-site assembly, resulting in a long installation and commissioning cycle and poor adaptability to the conditions of the factory site; (ii) Low efficiency of anaerobic ammoniation: Traditional anaerobic reactors only construct a single ORP gradient, which cannot match the reaction characteristics of stepwise hydrolysis and ammoniation of organic nitrogen; hydraulic stirring method is prone to forming water flow dead zone, resulting in poor mass transfer effect; (iii) Poor nitrogen removal effect: Conventional nitrogen removal reactors have a single aeration mode, low DO control accuracy, and limited overall nitrogen removal efficiency; (iv) High energy consumption: Traditional MBR requires high-intensity aeration to scrub the membrane surface, which consumes a lot of energy and the high DO sludge return disrupts the anoxic environment at the front end; (v) Low level of intelligence: process parameters are mostly adjusted manually, resulting in poor operational stability. Summary of the Invention

[0004] The purpose of this invention is to overcome the problems of poor treatment effect in the prior art and to provide an integrated, automated, and low-energy-consumption process and equipment for the treatment and reuse of high organic nitrogen wastewater from chemical fibers.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A process for integrated treatment and reuse of high organic nitrogen wastewater from chemical fiber processing is provided, including the following steps: Step 1: High organic nitrogen wastewater from chemical fibers enters the equalization tank to complete homogenization and equalization, and the pH value of the wastewater is adjusted to the range of 8.5~9.5. Then, it is pumped into the demulsification, coagulation and flotation unit, and targeted demulsifiers and flocculants are added to remove emulsified oils and suspended solids in the water. Step 2: The effluent from the air flotation enters the gradient anaerobic reactor, which forms an oxidation-reduction potential gradient and a sludge concentration gradient along the water flow direction, converting organic nitrogen in the wastewater into ammonia nitrogen and degrading organic matter. Step 3: The anaerobic effluent enters the overlapping biological denitrification reactor. Through the staggered operation of the non-foaming aeration system and the microporous aeration system in time or space, a dissolved oxygen gradient is formed in the reactor to achieve biological denitrification. Step 4: The denitrified mixture enters the non-aeration MBR membrane system, where mechanical reciprocating shaking of the membrane module replaces aeration and scrubbing to complete sludge-water separation; the MBR permeate is directly supplied to the RO reverse osmosis system, and some sludge is returned to the front end of the overlapping biological denitrification reactor; Step 5: The MBR permeate undergoes further treatment via an RO reverse osmosis system. The RO permeate is reused, while the concentrate is discharged. The entire process is controlled in real-time by a virtual intelligent expert algorithm system, achieving fully automated closed-loop operation.

[0006] In order to provide suitable ecological niches for different functional bacterial communities, the gradient anaerobic reactor in step two is divided into 3 to 5 gradient reaction zones along the water flow direction by a plate tower cross-flow structure. The oxidation-reduction potential gradient increases from -300 to -250 mV to -200 to -150 mV, and the sludge concentration gradient decreases step by step along the water flow direction.

[0007] To accommodate different influent ammonia nitrogen loads, the non-foaming aeration system and the microporous aeration system in step three are supplied with air by the same Roots blower, with a pressure reducing valve installed in the air supply branch of the non-foaming aeration system; the staggered operation includes the following two modes: Mode 1: The microporous aeration system and the non-foaming aeration system are turned on and off alternately at a set time interval. During non-foaming aeration, the dissolved oxygen is controlled at 0.3~0.5mg / L, and during microporous aeration, the dissolved oxygen is controlled at 0.8~1.0mg / L. Mode 2: Aeration valves at different aeration points are opened and closed alternately along the direction of water flow to create a continuous dissolved oxygen gradient of 0.2~1.0 mg / L in the reactor.

[0008] To achieve automation, the entire process is controlled in real time by a virtual intelligent expert algorithm system, realizing fully automated closed-loop operation from influent to effluent. The virtual intelligent expert algorithm system adjusts the frequency of mechanical reciprocating vibration in real time according to the transmembrane pressure difference of the non-aerated MBR membrane system; the dissolved oxygen in the membrane tank of the non-aerated MBR membrane system is maintained below 0.5 mg / L.

[0009] It also provides an integrated treatment and reuse equipment for high organic nitrogen wastewater from chemical fibers, which is integrated into one or more containers. It includes a regulating tank, a demulsification coagulation flotation unit, a gradient anaerobic reactor, an overlapping biological denitrification reactor, an aeration-free MBR membrane system, an RO reverse osmosis system, and a virtual intelligent expert algorithm system, which are arranged in sequence.

[0010] For details on the structure of each unit, please refer to the attached diagram and the section on specific implementation methods.

[0011] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art: 1. High degree of integration: All units are integrated into the container, with a modular design, small footprint, convenient installation, and short construction period; 2. High anaerobic ammoniation efficiency: By constructing a dual gradient environment of ORP and sludge concentration through the cross-flow structure of the plate tower, combined with a differentiated nitrification liquor reflux strategy and a coaxial multi-layer stirring system, the anaerobic hydrolysis, acid-producing, and methanogenic functional bacteria are spatially separated in an orderly manner, significantly improving the organic nitrogen ammoniation efficiency. 3. Excellent nitrogen removal effect and low energy consumption: The dual-mode operation of non-foaming aeration and microporous aeration forms a stable DO gradient, realizing short-cut nitrification and denitrification and in-situ synchronous nitrification and denitrification, which greatly saves aeration volume and the TN removal rate can reach more than 99%. 4. Significantly reduced energy consumption during MBR operation: Mechanical reciprocating vibration replaces aeration and scrubbing, completely eliminating membrane tank blower aeration, reducing energy consumption by more than 75%; at the same time, it avoids the disruption of the anoxic environment caused by the return of high-DO sludge. 5. Short process and no secondary pollution: MBR permeate is directly supplied to the RO system, eliminating the intermediate buffer tank and avoiding secondary pollution in the intermediate process; 6. Fully automated intelligent operation: The virtual intelligent expert algorithm system realizes closed-loop control of the entire process, unattended operation, dynamic optimization, and perfectly adapts to the characteristics of large fluctuations in water quality and quantity of chemical fiber wastewater. Attached Figure Description

[0012] The following sections will describe some specific embodiments of the invention in detail by way of example and not limitation, with reference to the accompanying drawings. The same reference numerals in the drawings denote the same or similar parts or portions. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings: Figure 1 This is a process flow diagram of the present invention; Figure 2 This is a schematic cross-sectional view of the pretreatment section of the present invention; Figure 3 for Figure 2 The diagram shows a top view of the preprocessing section. Figure 4 This is a schematic cross-sectional view of the core processing part of the present invention; Figure 5 for Figure 4 The diagram shows a top view of the core processing unit. Figure 6 This is a schematic diagram of a cyclone stirring system. The reference numerals in the attached figures are explained as follows: 1. Equalization tank; 11. Inlet I; 12. Swirl mixing system; 121. Swirl hood; 122. Swirl water distribution pipe; 123. Inlet pipe; 13. pH meter; 14. Static pressure level gauge; 15. Acid / alkali dosing port; 16. Raw water pump; 2. Demulsification, coagulation, and flotation unit; 21. Inlet II; 22. Vent outlet; 23. Chemical dosing reaction zone; 231. Demulsification chemical dosing tank; 232. PAM chemical dosing tank; 233. Mixer; 24. Dissolved air separation zone; 241. Dissolved air system; 242. Dissolved air release device; 243. Sludge scraping system; 25. Clear water tank; 251. Effluent weir plate; 252. Flotation effluent pump; 26. Automatic chemical dosing device I; 3. Gradient anaerobic reactor; 31. Inlet III; 32. Plate tower cross-flow structure; 33. Coaxial multi-layer stirring system; 331. Stirring motor; 332. Independent rotor; 34. ORP instrument; 35. Reflux port; 4. Overlapping biological denitrification reactor; 41. Bubble-free aeration system; 42. Microporous aeration system; 43. Mixed liquor reflux pump; 44. Mixed liquor lift pump; 45. Roots blower; 46. DO online instrument; 5. Non-aerated MBR membrane system; 51. Drive unit; 52. MBR membrane module; 53. Sludge return pump; 54. MBR permeate pump; 6. RO reverse osmosis system; 61. Security filter; 62. High-pressure pump; 63. RO membrane module; 64. Automatic dosing device II; 65. Product water outlet; 66. Concentrate outlet; 7. Virtual intelligent expert algorithm system; 8. Containers. Detailed Implementation

[0013] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. 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.

[0014] See Figures 1 to 5This example discloses an integrated treatment and reuse process and equipment for high organic nitrogen wastewater from chemical fiber processing. The entire system is integrated within one or more containers 8, including an equalization tank 1, a demulsification, coagulation, and flotation unit 2, a gradient anaerobic reactor 3, an overlapping biological denitrification reactor 4, an aeration-free MBR membrane system 5, an RO reverse osmosis system 6, and a virtual intelligent expert algorithm system 7. This equipment fundamentally solves the core bottlenecks of traditional chemical fiber wastewater treatment processes, such as low anaerobic ammonification efficiency, limited denitrification effect, and high MBR operating energy consumption, by constructing a dual-gradient anaerobic environment of ORP (oxidation-reduction potential) and sludge concentration, a dissolved oxygen gradient denitrification mode synergistic with bubble-free aeration and microporous aeration, and a direct connection between the aeration-free MBR and RO reverse osmosis mode.

[0015] The container is equipped with a ladder (not shown) and a maintenance platform (not shown) on its side for easy daily inspection and equipment maintenance. The processing capacity and dimensions of each treatment unit can be customized according to the water quality and quantity of high organic nitrogen wastewater from different chemical fibers, offering engineering advantages such as immediate installation and flexible expansion.

[0016] The following sections will introduce each part in detail.

[0017] See Figures 1 to 3 The equalization tank 1 is equipped with an inlet I 11, a vortex stirring system 12, a pH meter 13, a static pressure level gauge 14, an acid / alkali dosing port 15, and a raw water pump 16.

[0018] High-organic-nitrogen wastewater from chemical fiber processing enters equalization tank 1 through inlet I11. Unlike traditional equalization tanks that rely on external aeration pipes for agitation, the vortex mixing system 12 in this example is directly connected to the raw water pump 16. It utilizes the surplus effluent from the raw water pump 16 for self-circulating hydraulic mixing via an in-tank vortex distributor. This design eliminates the need for additional aeration blowers, simplifying equipment configuration and reducing operating energy consumption while achieving uniform wastewater quality and quantity.

[0019] like Figure 6 The swirling mixing system 12 includes a swirling shroud 121 and a swirling water distribution pipe 122. The swirling shroud 121 has a conical hollow structure with an open bottom. The swirling water distribution pipe 122 is horizontally arranged inside the swirling shroud 121, with outlets at both ends facing opposite directions. The water outlet direction is along the tangent of the cone shape and is basically perpendicular to the main body of the swirling water distribution pipe 122. The middle of the swirling water distribution pipe 122 is connected to an inlet pipe 123, through which water enters. In this way, the water outlet of the swirling water distribution pipe 122 forms a swirling flow inside the swirling shroud 121 and is finally released from the bottom edge of the swirling shroud 121.

[0020] like Figure 2 , Figure 3 The raw water pump 16 draws water from the equalization tank 1 and sends it to the inlet pipe 123 and the demulsification coagulation flotation unit 2 (described later) in two separate routes.

[0021] pH meter 13 is linked to the dosing pump at acid / alkali inlet 15. When pH meter 13 detects that the pH value of the wastewater in the tank deviates from the range of 8.5 to 9.5, the virtual intelligent expert algorithm system 7 automatically starts and stops the dosing pump, adding acid or alkali to adjust the pH value and ensure that the effluent pH value remains stable within the set range. Static pressure level gauge 14 monitors the liquid level in regulating tank 1 in real time and is interlocked with raw water pump 16 to prevent raw water pump 16 from running dry.

[0022] See Figure 1 , Figure 2 and Figure 3 The demulsification, coagulation, and flotation unit 2 is internally divided into a chemical dosing reaction zone 23, a dissolved air separation zone 24, and a clear water tank 25.

[0023] The chemical dosing reaction zone 23 is sequentially equipped with a demulsification dosing tank 231 and a PAM dosing tank 232, each containing a mixer 233. Overflow occurs between the demulsification dosing tank 231 and the PAM dosing tank 232. Water from the equalization tank is pumped to inlet II 21 by the raw water pump 16. Targeted demulsifier and PAM flocculant are added to the demulsification dosing tank 231 and the PAM dosing tank 232 respectively, and react fully under the action of the mixer 233 to form dense flocs. The effluent from the chemical dosing reaction zone 23 is connected to the dissolved air separation zone 24.

[0024] The dissolved air separation zone 24 includes a dissolved air system 241, a dissolved air releaser 242, and a scum scraping system 243. The dissolved air system 241 draws clean water from the clear water tank 25 and mixes it with compressed air. The resulting high-pressure dissolved air water is released after depressurization by the dissolved air releaser 242, producing a large number of tiny, uniformly distributed bubbles. The "floc-bubble" composite formed by the combination of bubbles and flocs rapidly rises to the water surface under buoyancy, forming a scum layer, which is continuously scraped off by the scum scraping system 243. The separated clean water enters the clear water tank 25 through a pipe.

[0025] The clear water tank 25 is equipped with an outlet weir 251 and an air flotation outlet pump 252. The height of the outlet weir 251 is adjustable to precisely control the system liquid level. The air flotation outlet pump 252 pumps the clear water in the clear water tank 25 to the subsequent gradient anaerobic reactor 3.

[0026] The automatic dosing device I26 is used to automatically add acid, alkali, targeted demulsifier and PAM flocculant to the corresponding reaction tank.

[0027] Vent vents 22 are provided at the bottom of the dosing reaction zone 23, the dissolved gas separation zone 24, and the clear water tank 25.

[0028] See Figure 1 , Figure 4 and Figure 5The gradient anaerobic reactor 3 is equipped with an inlet III 31, a plate tower cross-flow structure 32, a coaxial multi-layer stirring system 33, and an ORP instrument 34. Multiple reflux ports 35 are located along the reactor's flow path. The gradient anaerobic reactor 3 aims to solve the core problem of traditional anaerobic reactors, which suffer from a homogeneous internal environment and are unable to provide suitable ecological niches for different functional bacterial communities.

[0029] Specifically, the plate tower cross-flow structure 32 divides the gradient anaerobic reactor 3 into 3 to 5 gradient reaction zones along the water flow direction, used to construct ORP and sludge concentration gradients along the water flow direction. In this embodiment, a total of 3 gradient reaction zones are set up. Along the water flow direction, the ORP gradient increases from -300 to -250 mV to -200 to -150 mV, while the sludge concentration gradually decreases along the water flow direction. This dual-gradient environment allows anaerobic hydrolytic bacteria, acid-producing bacteria, and methanogenic bacteria to accumulate and grow in their most suitable redox potential and sludge concentration regions, achieving spatially ordered separation and synergistic metabolism of functional bacterial communities.

[0030] The coaxial multi-layer mixing system 33 includes a mixing motor 331 and independent rotors 332 arranged in layers along the axial direction. The rotation speed of each independent rotor 332 can be set independently to adapt to the mixing needs of different sludge concentration ranges. Furthermore, the size of the mixing blades is customized according to the sludge concentration of the corresponding layer; the higher the sludge concentration, the larger the size of the mixing blades, ensuring that each layer obtains a suitable mixing effect and preventing sludge deposition.

[0031] To ensure the long-term stability of the dual-gradient environment of ORP and sludge concentration, a differentiated reflux strategy was introduced in this case. The virtual intelligent expert algorithm system 7, based on the real-time monitoring values ​​of the ORP meters 34 in each section of the gradient anaerobic reactor 3, regulates the mixed liquor reflux pump 43 located in the overlapping biological denitrification reactor 4. The nitrate-rich mixed liquor is refluxed differentially into each gradient reaction zone of the gradient anaerobic reactor 3 through reflux ports 35 at different locations. By adjusting the reflux distribution ratio at each reflux port, the required electron acceptors are precisely replenished in each section, stabilizing the set ORP and sludge concentration gradients within the reactor. After treatment in the gradient anaerobic reactor 3, organic nitrogen in the wastewater is efficiently converted into ammonia nitrogen, most organic matter is degraded, and the biodegradability of the effluent is significantly improved.

[0032] See Figure 1 , Figure 4 and Figure 5The overlapping biological denitrification reactor 4 is structurally designed with an overlapping arrangement of a bubble-free aeration system 41 and a microporous aeration system 42. Both are supplied with air by a Roots blower 45. Considering the significant difference in air supply pressure between the two aeration methods—the bubble-free aeration system 41 only requires low-pressure gas to pass through the hollow fiber membrane wall for bubble-free oxygen transfer, while the microporous aeration system 42 requires higher pressure to overcome water pressure and generate microbubbles—a pressure reducing valve is installed on the air supply branch of the bubble-free aeration system 41 to meet its low-pressure air supply requirements, while the air supply branch of the microporous aeration system 42 directly supplies the Roots blower with full-pressure gas to meet its aeration pressure requirements. Each air supply branch is equipped with an automatically adjustable aeration valve.

[0033] The reactor is equipped with an online DO instrument 46 and a mixed liquor lift pump 44 at the outlet. The outlet of the mixed liquor lift pump 44 is connected to the front end of the non-aerated MBR membrane system 5.

[0034] The overlapping biological denitrification reactor 4 is equipped with two aeration operation modes, which are monitored by the DO online instrument 46 and automatically regulated by the virtual intelligent expert algorithm system 7. By controlling the opening and closing and the degree of opening of each aeration valve, the mode switching and the precise control of dissolved oxygen can be achieved.

[0035] Aeration Mode 1 (Intermittent On / Off Mode): The microporous aeration system 42 and the non-foaming aeration system 41 are alternately turned on and off at a set time interval; during microporous aeration, the dissolved oxygen in the reactor is controlled at 0.8-1.0 mg / L, and during non-foaming aeration through the hollow fiber membrane, the dissolved oxygen is controlled at 0.3-0.5 mg / L, forming a low-oxygen environment in the mixed liquor to promote short-cut nitrification.

[0036] Aeration Mode 2 (Spatial Interleaved Opening and Closing Mode): Aeration valves at different aeration points are opened and closed alternately along the water flow direction, creating a continuous dissolved oxygen gradient of 0.2–1.0 mg / L within the reactor. In this mode, the dissolved oxygen is lower in the initial stage, which is beneficial for denitrifying bacteria to reduce nitrate nitrogen to nitrogen gas; the dissolved oxygen gradually increases in the middle and later stages, meeting the needs of nitrifying bacteria to oxidize ammonia nitrogen to nitrate nitrogen.

[0037] Furthermore, the bubble-free aeration system 41 adopts a membrane aeration bioreactor structure. The biofilm attached to the membrane surface naturally forms a layered structure with an aerobic inner side and an anoxic outer side, realizing in-situ simultaneous nitrification and denitrification, further improving denitrification efficiency while reducing aeration energy consumption.

[0038] See Figure 1 , Figure 4 and Figure 5 The non-aeration MBR membrane system 5 includes a drive unit 51, a non-aeration MBR membrane module 52, a sludge return pump 53, and an MBR permeate pump 54.

[0039] Unlike traditional MBRs that rely on high-intensity aeration to scrub the membrane surface and control fouling, the aeration-free MBR membrane system 5 in this example uses the hydraulic shearing effect generated by the reciprocating vibration of the membrane modules instead of aeration scrubbing. Specifically, the drive unit 51 drives the aeration-free MBR membrane module 52 to reciprocate within the membrane tank, inhibiting the deposition and adhesion of pollutants on the membrane surface through the relative shearing effect generated by the membrane fibers in the water. This design completely eliminates the aeration system in the membrane tank, significantly reducing the operating energy consumption of the MBR and ensuring a low dissolved oxygen state within the membrane tank. In this embodiment, the dissolved oxygen inside the membrane tank is maintained below 0.5 mg / L, and the dissolved oxygen in the sludge return liquid is controlled below 0.3 mg / L, effectively avoiding the damage to the dissolved oxygen environment of the overlapping biological denitrification reactor 4 caused by high dissolved oxygen return.

[0040] The virtual intelligent expert algorithm system 7 adjusts the frequency of reciprocating vibration in real time based on the transmembrane pressure difference of the membrane system. During normal operation, the vibration frequency is maintained within a low baseline range; when the transmembrane pressure difference increases, the system automatically increases the vibration frequency to enhance the hydraulic shearing effect on the membrane surface and delay membrane fouling; when the transmembrane pressure difference returns to normal, the vibration frequency is automatically reduced to save drive energy consumption.

[0041] The outlet of sludge return pump 53 is connected to the front end of the overlapping biological denitrification reactor 4, used to return the activated sludge retained in the membrane tank to the overlapping biological denitrification reactor 4 to maintain the sludge concentration in the reactor. The outlet of MBR permeate pump 54 is directly connected to the inlet of the security filter 61 of RO reverse osmosis system 6, eliminating the intermediate buffer tank in the traditional process, shortening the treatment process, and avoiding secondary pollution in the intermediate links.

[0042] See Figure 4 , Figure 5 The RO reverse osmosis system 6 includes a security filter 61, a high-pressure pump 62, an RO membrane module 63, and an automatic dosing device II 64.

[0043] The outlet of MBR permeate pump 54 is directly connected to the inlet of security filter 61. The outlet of security filter 61 is connected to the inlet of RO membrane module 63 via high-pressure pump 62. The permeate outlet 65 of RO membrane module 63 is connected to the reuse pipeline, and the produced reclaimed water is reused in the chemical fiber production process. The concentrate outlet 66 of RO membrane module 63 is connected to the municipal sewage network, and the qualified concentrate is discharged into the municipal network. Automatic dosing device II 64 can add scale inhibitors and reducing agents according to the influent water quality to prevent RO membrane scaling and oxidative damage, ensuring the long-term stable operation of the membrane system.

[0044] The virtual intelligent expert algorithm system 7 can obtain process parameters such as DO, ORP, pH, transmembrane pressure difference, and pressure in real time from online monitoring instruments distributed in each unit, and adjust the mixed liquor return pump 43, each aeration valve, sludge return pump 53, MBR drive unit 51, RO high pressure pump 62 and each automatic dosing device accordingly.

[0045] In terms of gradient anaerobic control, the system adjusts the reflux flow rate of the mixed liquor reflux pump 43 and the distribution ratio of each reflux port 35 according to the monitoring values ​​of the ORP meter 34 in each section of the gradient anaerobic reactor 3, so as to stabilize the ORP value of each section within the set range.

[0046] In terms of overlapping biological nitrogen removal control, the system automatically selects the aeration operation mode based on the influent ammonia nitrogen load data, and adjusts the opening and closing of each aeration valve and the degree of opening through the DO online instrument 46 to achieve precise control of dissolved oxygen. When the influent ammonia nitrogen load is moderate, mode one is used first to reduce aeration energy consumption; when the influent water quality fluctuates greatly or the total nitrogen removal requirement is high, it switches to mode two to form a more stable dissolved oxygen gradient.

[0047] In terms of MBR control without aeration, the system monitors the changing trend of transmembrane pressure difference in real time. When the rate of increase of transmembrane pressure difference exceeds the set threshold, the frequency of membrane module vibration is automatically increased to achieve preventive control of membrane fouling.

[0048] The system supports automatic and manual dual-mode switching and features data storage, operation curve display, audible and visual alarms, and remote monitoring. When any process parameter exceeds its limit, the system automatically triggers an emergency control program to ensure stable process operation. The application of this system achieves fully automated closed-loop operation from influent to effluent, with operational stability and adaptability far exceeding traditional manual control, making it suitable for the large fluctuations in water quality and quantity of chemical fiber wastewater.

[0049] Each processing unit is integrated within one or more stainless steel containers 8. Container 8 has ladders and maintenance platforms (not shown in the diagram) on its sides for easy daily inspection and equipment maintenance. The containerized integrated design results in a small footprint, convenient installation and transportation, and a short construction period, making it particularly suitable for new projects and upgrades in chemical fiber plants with limited space.

[0050] The following details the beneficial technical effects of this invention through actual operation: This embodiment uses a single 80m³ / d containerized integrated treatment unit to treat high organic nitrogen wastewater from aramid production. Wastewater influent quality: COD=11000mg / L, TN=1000mg / L, Kjeldahl nitrogen=850mg / L, SS=200mg / L, pH=5.8~6.2. Equipment configuration: Two 40-foot stainless steel high cabinets are connected in series, housing an equalization tank, a demulsification coagulation flotation unit, a gradient anaerobic reactor, a superimposed biological denitrification system, a non-aerated MBR, and RO reverse osmosis. The gradient anaerobic reactor has four gradient reaction zones and four layers of coaxial stirring rotors. The superimposed biological denitrification reactor has a non-aerated membrane area of ​​4020m², the non-aerated MBR has a membrane area of ​​800m², and the RO system is equipped with four spiral wound membrane modules. Main operating parameters: pH in the equalization tank is automatically adjusted to 8.5~9.5; demulsifying, coagulating, and flotation targeted demulsifier dosage is 6 mg / L, and PAM dosage is 0.8 mg / L; gradient anaerobic digestion automatically adjusts the ORP gradient to -280mV→-260mV→-220mV→-180mV, and the sludge concentration gradient is 10000→9000→7000→6000 mg / L; the stirring speed is independently adjustable to 25, 22, 15, and 10 r / min; the overlapping biological denitrification adopts a time-intermittent alternating aeration mode with an alternation cycle of 35 min and MLSS=8000 mg / L; the non-aerated MBR membrane flux is 22 L / (m²·h); the RO operating pressure is 1.2 MPa, and the permeate rate is 70%. The entire process is controlled in real time by a virtual intelligent expert algorithm system to achieve fully automated closed-loop operation.

[0051] Treatment results: RO permeate COD ≤ 25 mg / L, TN ≤ 3.5 mg / L, SS ≤ 0.5 mg / L, exceeding the standards for cleaning water in chemical fiber production, with a reuse rate of 70%; RO concentrate COD = 350 mg / L, TN = 32 mg / L, meeting discharge standards. The entire process achieves a TN removal rate of 99.65% and a COD removal rate of 99.77%, with a unit energy consumption of only 0.9 kW·h / m³, saving more than 75% compared to traditional processes. In terms of operation and maintenance, the equipment requires no dedicated personnel: weekly cleaning of the sludge scraper and inspection of the membrane modules and aeration system; weekly online cleaning of the MBR; RO chemical cleaning every 3 months; monthly data backup and annual upgrades of the virtual system; only one maintenance personnel are needed for daily comprehensive inspections to ensure long-term stable operation.

[0052] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. An integrated treatment and reuse process for high organic nitrogen wastewater from chemical fiber processing, characterized in that, Includes the following steps: Step 1: High organic nitrogen wastewater from chemical fibers enters the equalization tank to complete homogenization and equalization, and the pH value of the wastewater is adjusted to the range of 8.5~9.

5. Then, it is pumped into the demulsification, coagulation and flotation unit, and targeted demulsifiers and flocculants are added to remove emulsified oils and suspended solids in the water. Step 2: The effluent from the air flotation enters the gradient anaerobic reactor, which forms an oxidation-reduction potential gradient and a sludge concentration gradient along the water flow direction, converting organic nitrogen in the wastewater into ammonia nitrogen and degrading organic matter. Step 3: The anaerobic effluent enters the overlapping biological denitrification reactor. Through the staggered operation of the non-foaming aeration system and the microporous aeration system in time or space, a dissolved oxygen gradient is formed in the reactor to achieve biological denitrification. Step 4: The denitrified mixture enters the non-aeration MBR membrane system, where mechanical reciprocating shaking of the membrane module replaces aeration and scrubbing to complete sludge-water separation; the MBR permeate is directly supplied to the RO reverse osmosis system, and some sludge is returned to the front end of the overlapping biological denitrification reactor; Step 5: The MBR permeate is further treated by the RO reverse osmosis system. The RO permeate is reused, and the concentrate is discharged.

2. The process according to claim 1, characterized in that: In step two, the gradient anaerobic reactor is divided into 3 to 5 gradient reaction zones along the water flow direction by a plate tower cross-flow structure. The oxidation-reduction potential gradient increases from -300 to -250 mV to -200 to -150 mV, and the sludge concentration gradient decreases step by step along the water flow direction.

3. The process according to claim 1, characterized in that: The bubble-free aeration system and the microporous aeration system mentioned in step three are supplied with air by the same Roots blower, wherein the air supply branch of the bubble-free aeration system is equipped with a pressure reducing valve; the staggered operation includes the following two modes: Mode 1: The microporous aeration system and the non-foaming aeration system are turned on and off alternately at a set time interval. During non-foaming aeration, the dissolved oxygen is controlled at 0.3~0.5mg / L, and during microporous aeration, the dissolved oxygen is controlled at 0.8~1.0mg / L. Mode 2: Aeration valves at different aeration points are opened and closed alternately along the direction of water flow to create a continuous dissolved oxygen gradient of 0.2~1.0 mg / L in the reactor.

4. The process according to claim 1, characterized in that: The entire process is controlled in real time by a virtual intelligent expert algorithm system, realizing fully automated closed-loop operation from water inlet to water outlet. The virtual intelligent expert algorithm system adjusts the frequency of mechanical reciprocating vibration in real time according to the transmembrane pressure difference of the non-aerated MBR membrane system. The dissolved oxygen in the membrane tank of the non-aerated MBR membrane system is maintained below 0.5 mg / L.

5. An integrated treatment and reuse device for high organic nitrogen wastewater from chemical fiber processing plants, characterized in that: The equipment is integrated into one or more containers (8), which include a regulating tank (1), a demulsification coagulation flotation unit (2), a gradient anaerobic reactor (3), an overlapping biological denitrification reactor (4), an aeration-free MBR membrane system (5), an RO reverse osmosis system (6), and a virtual intelligent expert algorithm system (7) for full-process control.

6. The device according to claim 5, characterized in that: The gradient anaerobic reactor (3) is equipped with an inlet (31), a plate tower cross-flow structure (32), a coaxial multi-layer stirring system (33), and an ORP instrument (34). The reactor is equipped with multiple return ports (35) along its flow path. The plate tower cross-flow structure (32) divides the gradient anaerobic reactor (3) into 3 to 5 gradient reaction zones along the water flow direction. The virtual intelligent expert algorithm system (7) controls the mixed liquor return pump (43) located in the overlapping biological denitrification reactor (4) according to the real-time monitoring value of the ORP instrument (34) in each gradient reaction zone. The mixed liquor rich in nitrate nitrogen is returned to different gradient reaction zones through the return ports (35) at different locations to maintain the oxidation-reduction potential gradient and sludge concentration gradient along the water flow direction.

7. The device according to claim 5, characterized in that: The overlapping biological denitrification reactor (4) has a non-foaming aeration system (41) and a microporous aeration system (42) arranged in an overlapping manner, both of which are supplied with gas by a Roots blower (45); the non-foaming aeration system (41) is equipped with a pressure reducing valve on the gas supply branch, and the microporous aeration system (42) directly supplies the Roots blower with full-pressure gas on the gas supply branch. Each gas supply branch is equipped with an automatically adjustable aeration valve; the reactor is equipped with an online DO instrument (46) and a mixed liquor return pump (43); the non-foaming aeration system (41) adopts a membrane aeration bioreactor structure.

8. The device according to claim 5, characterized in that: The non-aeration MBR membrane system (5) includes a drive device (51), a non-aeration MBR membrane module (52), a sludge return pump (53), and an MBR permeate pump (54); the drive device (51) drives the non-aeration MBR membrane module (52) to perform reciprocating shaking motion in the membrane tank; the virtual intelligent expert algorithm system (7) adjusts the frequency of reciprocating shaking in real time according to the transmembrane pressure difference; the outlet of the sludge return pump (53) is connected to the front end of the overlapping biological denitrification reactor (4); the outlet of the MBR permeate pump (54) is directly connected to the inlet of the security filter (61) of the RO reverse osmosis system (6).

9. The device according to claim 5, characterized in that: The virtual intelligent expert algorithm system (7) is connected to the online monitoring instruments of each unit, the mixed liquor return pump (43), each aeration valve, the sludge return pump (53), the MBR drive device (51), the RO high pressure pump (62), and each automatic dosing device. It is used to perform linkage control based on the process parameters obtained in real time. The system supports automatic and manual dual-mode switching and has data storage, operation curve display, audible and visual alarm and remote monitoring functions.

10. The device according to claim 5, characterized in that: The regulating tank (1) is equipped with a swirling stirring system (12), which is connected to the raw water pump (16) and uses part of the effluent from the raw water pump for self-circulating hydraulic stirring; the coaxial multi-layer stirring system (33) of the gradient anaerobic reactor (3) includes a stirring motor (331) and independent rotors (332) arranged in layers along the axial direction, and the speed of each independent rotor (332) can be set independently.

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