Device and method for efficiently treating aquaculture wastewater by deeply coupling SND-AO process with sulfur autotrophic denitrification

Abstract

The invention discloses a device and a method for efficiently treating aquaculture wastewater by deeply coupling an SND-AO process with sulfur autotrophic denitrification. The device provided by the invention is based on a microenvironment theory of synchronous short-cut nitrification and denitrification and a sulfur autotrophic denitrification technology, tight substance exchange is realized through specific circulating reflux setting, the stability of the device is prevented from being influenced by an external environment due to a segmented deep coupling design, sulfate radicals are reduced to generate hydrogen sulfide in a gas phase and S < 2-> in a liquid phase, and the sulfur content in the gas phase is reduced. The sulfur autotrophic denitrification is enhanced through recycling, so that the pollutant removal efficiency is improved, the waste of sulfur elements is reduced, and the content of sulfate by-products is reduced. The device disclosed by the invention realizes efficient removal of nitrogen and organic pollutants in the aquaculture wastewater and cyclic utilization of sulfur, remarkably improves the operation stability, treatment effect and economical efficiency of the device, and is particularly suitable for efficient treatment of the aquaculture wastewater containing complex pollutants; the goal of efficiently removing organic pollutants and nitrogen pollution in the aquaculture wastewater is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of wastewater treatment, and more specifically, relates to a device and method for efficiently treating aquaculture wastewater by deeply coupling sulfur autotrophic denitrification with a SND-AO process. Background Art

[0002] With the rapid advancement of my country's agricultural modernization, livestock and poultry farming has gradually developed from small-scale and decentralized to intensive and large-scale. Traditional farms have gradually moved to the periphery of cities and towns. Although this has improved production efficiency, it has also brought serious environmental pollution problems. In particular, aquaculture wastewater has significantly increased the difficulty of treatment due to its complex water quality, high concentrations of ammonia nitrogen, total nitrogen and organic matter, and large fluctuations in emissions.

[0003] Since aquaculture wastewater not only contains high concentrations of organic pollutants and high concentrations of suspended solids, but is also rich in nutrients such as nitrogen and phosphorus, and has a high ammonia nitrogen content, it brings great difficulties to denitrification treatment, which is more difficult than the treatment of other domestic wastewater or dye wastewater. For example, existing studies have specifically used ammonia stripping process to treat aquaculture wastewater, but this method is not suitable for large-scale treatment. At the same time, the stripping process may also cause the pH value and COD mass concentration of the wastewater to increase, making it difficult to meet the emission standards. Therefore, the current treatment of aquaculture wastewater usually relies on the "A / O (anoxic / aerobic) + deep treatment" process, but this process still has many limitations, such as consuming a large amount of organic matter in the anaerobic / anoxic process, resulting in insufficient carbon source in the subsequent denitrification process, limiting the nitrogen removal efficiency. Even with a two-stage A / O process, the nitrogen removal rate is only 70%-80%, which is difficult to meet more stringent emission standards. The deep treatment unit mostly uses heterotrophic denitrification filter tanks, which require additional carbon sources, which not only increases the treatment cost, but also may cause secondary pollution.

[0004] In order to avoid adding an external carbon source, existing research has combined sulfur autotrophic denitrification (SAD) technology for treatment, using a reduced sulfur source to react in an anaerobic environment to reduce nitrates to nitrogen. In this process, sulfur oxidation and nitrogen reduction occur simultaneously, which can remove sulfur ions and nitrates at the same time, achieving the effect of treating waste with waste. However, this method will generate a large amount of sulfate byproducts, making the water smelly. There are also problems such as sulfur waste, pH fluctuations in the system effluent, and unstable treatment effects. For example, existing studies have combined sulfur autotrophic denitrification with short-range denitrification anaerobic ammonium oxidation to simultaneously remove ammonia nitrogen and nitrite nitrogen through anaerobic ammonium oxidation, but this method is not suitable for the treatment of aquaculture wastewater, and the device also needs to supplement alkalinity through exogenous sources and adjust pH to balance the stability of the sulfur autotrophic reaction itself; in short-range denitrification coupled with anaerobic ammonium oxidation, although it is mainly used to remove nitrogen, in the short-range denitrification process, excessive organic matter content will preferentially promote the growth of heterotrophic denitrifying bacteria, thereby inhibiting the activity of anaerobic ammonium oxidizing bacteria, resulting in low reaction efficiency and even system collapse. Using an internal circulation anaerobic reactor to treat aquaculture wastewater can achieve a higher organic matter removal rate, but the ammonia nitrogen concentration in the effluent may increase compared to the influent. Therefore, sulfur autotrophic denitrification combined with anaerobic treatment technology usually cannot achieve a high denitrification rate. Since aquaculture wastewater treatment is a complex process, current wastewater treatment technologies often find it difficult to achieve ideal denitrification effects, and their treatment effects need to be improved. Therefore, there is still a lack of devices and methods that can efficiently denitrify aquaculture wastewater. In order to improve the denitrification rate and overall treatment effect of aquaculture wastewater, maintain reaction stability, reduce pH fluctuations, and reduce the production of by-products, more new devices and methods that can efficiently and stably treat aquaculture wastewater need to be developed, so as to achieve the purpose of deep denitrification of aquaculture wastewater and energy saving and consumption reduction. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the defects of low denitrification rate of existing aquaculture wastewater and the shortcomings of devices and methods for treating aquaculture wastewater, and to provide a device and method for efficiently treating aquaculture wastewater by deeply coupling sulfur autotrophic denitrification through a SND-AO process.

[0006] The purpose of the present invention is to provide a device for efficiently treating aquaculture wastewater by deeply coupling sulfur autotrophic denitrification through a SND-AO process.

[0007] Another object of the present invention is to provide application of the above device.

[0008] Another object of the present invention is to provide a method for efficiently treating aquaculture wastewater by deeply coupling sulfur autotrophic denitrification through a SND-AO process.

[0009] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0010] A device and method for treating aquaculture wastewater by deeply coupling sulfur autotrophic denitrification with SND-AO process, comprising an aquaculture wastewater tank, a SND-AO system, a sulfur autotrophic denitrification-SAD reactor, a water outlet tank, and an electrical automatic control system connected in sequence; the SND-AO system comprises an SND pool, an A pool, and an O pool arranged adjacently; wherein the SND pool is provided with a water inlet Ⅰ, a mud discharge valve, an aeration fan, a stirrer Ⅰ, an aeration plate Ⅰ, an overflow port Ⅰ, a sensor assembly Ⅰ, and a reflux port Ⅰ; The mud valve and aeration plate Ⅰ are arranged at the bottom of the SND pool, and the aeration plate Ⅰ is connected to the aeration fan, and the wastewater enters the A pool through the overflow port Ⅰ; the A pool is a closed pool, and is provided with a stirrer Ⅱ, overflow port Ⅱ, air outlet Ⅰ, reflux port Ⅱ, reflux port Ⅲ, sensor assembly Ⅱ, and water outlet; the overflow port Ⅱ is arranged on the side close to the O pool and opposite to the overflow port Ⅰ; the air outlet Ⅰ is arranged at the top of the A pool and connected to the vortex fan, the reflux port Ⅱ is connected to the reflux port Ⅴ of the sulfur autotrophic denitrification-SAD reactor, and the water outlet is connected to the sulfur autotrophic denitrification reactor. The denitrification-SAD reactor is connected to the water inlet II, and the wastewater enters the O tank through the overflow port II; the O tank is provided with a stirrer III, an aeration plate II, a reflux port IV, a suction pump, a membrane assembly, a liquid level sensor, and a sensor assembly III; the aeration plate II is arranged at the bottom of the O tank and connected to the aeration fan, and the membrane assembly is connected to the suction pump and the water outlet tank in sequence; the sulfur autotrophic denitrification-SAD reactor is provided with sulfur-containing biological fillers, an air distribution plate, a water inlet II, an air outlet II, a reflux port V, a positive and negative pressure protector, a sensor assembly IV, One-way valve; the air distribution plate and the water inlet II are arranged at the bottom of the sulfur autotrophic denitrification-SAD reactor, the positive and negative pressure protectors are arranged at the top of the sulfur autotrophic denitrification-SAD reactor, and the air outlet II is connected to the vortex fan through a one-way valve; the reflux port IV of the O tank is connected to the reflux port I, the reflux port II, and the water inlet II in sequence; the electrical automatic control system is electrically connected to the aquaculture wastewater tank, the aeration fan, the stirrer I, the stirrer II, the stirrer III, the sensor components I to IV, the liquid level sensor, the membrane component, and the suction pump.

[0011] The invention utilizes the deep coupling of the synchronous shortcut nitrification and denitrification technology (SND), the anaerobic aerobic technology (AO) and the sulfur autotrophic denitrification (SAD), and proposes a system device for efficiently treating aquaculture wastewater based on the deep coupling of the synchronous shortcut nitrification and denitrification reactor (SND), the anaerobic aerobic reactor (AO) and the sulfur autotrophic denitrification (SAD). The system device integrates four main areas, namely, the synchronous shortcut nitrification and denitrification (SND pool), the anaerobic pool (A pool), the sulfur autotrophic denitrification pool (SAD pool) and the aerobic pool (O pool). Through a specific circulation setting and precise aeration control of the dissolved oxygen content (DO), the system is ensured to operate under the optimal conditions. The circulation zoning setting can synergistically treat nitrogen, sulfur and organic pollutants without the need for additional addition of a carbon source. The system device can efficiently and stably treat aquaculture wastewater, and realize the deep denitrification of aquaculture wastewater and the efficient recycling of resources. The device of the present invention strengthens the material flow through circulation, utilizes the mutual matching of production and demand in each area, is beneficial to the stability of regional reactions, reduces the influence of external conditions (such as pH, electron donors, etc.) on the overall system, and realizes efficient removal of nitrogen. The device of the present invention can realize the self-circulation of SND-AO-SAD, and can also complete the internal circulation of OA / SND and OA / SAD-A. Among them, after the aquaculture wastewater is sent to the SND pool for reaction, it enters the A pool, and the hydrogen sulfide gas produced by the reduction reaction is transported to the SAD. While ensuring that the electron donors in the sulfur autotrophic denitrification-SAD reactor are sufficient, the removal of COD in the wastewater by the A pool is strengthened, and the sulfate content of the effluent can be reduced; the sulfur autotrophic denitrification uses the sulfide in the biological filler module as an electron donor, and through the reduction of the nitrate in the system, efficient denitrification is realized without the need for an external carbon source; at the same time, the sulfate ions produced in the SAD are recycled to the A pool, and then the sulfate ions are reduced to generate hydrogen sulfide in the gas phase and S in the liquid phase. 2-Sulfur autotrophic denitrification is carried out to strengthen the removal and stability of organic matter by the system, and the efficiency of sulfur autotrophic denitrification is further improved, thereby achieving deep denitrification. The setting of the circulation of the material realizes the mutual promotion of the two reactors; finally, the water is discharged through the membrane reactor of the O pool. The present invention realizes the deep treatment of aquaculture wastewater without the need for an external carbon source. Compared with the traditional process, the device of the present invention significantly improves the denitrification efficiency, and the device itself can reach alkalinity balance without the need to supplement alkalinity. After operation, the pH of the system does not drop significantly, and stable reaction conditions are maintained; compared with the ordinary aquaculture wastewater two-stage AO system treatment, the residence time is shorter, and the treatment efficiency is improved; at the same time, the entire system setting is optimized, the operating energy consumption and floor space are reduced, and it has economic and environmental advantages, and promotes the development of wastewater treatment technology in a more efficient, environmentally friendly and economical direction.

[0012] The technical principle involved in the device of the present invention is that the aquaculture wastewater first enters the synchronous short-range nitrification and denitrification zone (SND pool), and in this area, by accurately controlling the dissolved oxygen (DO less than 0.3 mg / L) and the redox potential (ORP is -50 to +50 mv), a suitable micro-oxygen environment is achieved, so that nitrifying bacteria and denitrifying bacteria coexist, and synchronous short-range nitrification and denitrification are achieved, and organic matter (COD), ammonia nitrogen and total nitrogen (TN) in the aquaculture wastewater are effectively removed. The wastewater after SND treatment overflows into the anaerobic pool (pool A), which is in an anaerobic or anoxic state, which involves the conversion of ammonia nitrogen. Nitrates and nitrites in the wastewater are reduced to nitrogen gas by denitrifying bacteria in an anaerobic environment, thereby further removing nitrogen in the wastewater. At the same time, pool A provides a suitable reducing environment, which is conducive to the enrichment of sulfate-reducing bacteria, achieving the recycling of sulfur elements and reducing sulfate emissions, and the reduction of sulfate also strengthens the removal of COD. In order to ensure the smooth progress of this series of reactions, the redox potential (ORP) in pool A is controlled between -120 and -160 mV. An oxidizing environment is provided in the O pool, which can convert ammonia nitrogen into nitrate nitrogen. Nitrate nitrogen can be used as the main removal object in SAD, and it also has a certain removal effect on COD in the O pool. The mixed liquid of pool A and pool O is pumped into the sulfur autotrophic denitrification zone (SAD) through circulation. In this area, sulfur-containing biological carriers slowly release sulfide as electron donors, while enriching sulfur autotrophic bacteria to achieve deep denitrification. At the same time, the hydrogen sulfide gas produced in pool A is transmitted to the SAD to enhance the denitrification effect and ensure the stability of the system; and the SO4 produced by the SAD 2- The circulating effluent is reused in Pool A, where it undergoes a reduction reaction to produce hydrogen sulfide gas for SAD. The wastewater from Pool A and SAD treatment enters Pool O, where the membrane bioreactor (MBR) components are started to react and further remove ammonia nitrogen and organic matter. At the same time, the MBR components are used for efficient mud-water separation to improve the effluent quality, and the effluent is finally treated.

[0013] Furthermore, the aquaculture wastewater tank is provided with a lifting pump, a solenoid valve, and a flow meter which are connected in sequence, and is connected to the water inlet of the SND pool.

[0014] Furthermore, the sensor assembly I in the SND pool includes: pH sensor, DO sensor I, ORP sensor I, MLSS sensor, NH4 + -N sensor, NO2 - -N sensor Ⅰ, NO3 - -N sensor Ⅰ;

[0015] The sensor assembly II in pool A includes: H2S gas sensor I, ORP sensor II, DO sensor II, S 2- Sensor I;

[0016] The sensor component III in the O pool includes: DO sensor III, NO3 - -N sensor II.

[0017] Furthermore, the sensor assembly IV in the sulfur autotrophic denitrification-SAD reactor includes: H2S gas sensor II, NO2 - -N sensor Ⅱ, NO3 - -N sensor Ⅲ, S 2- Sensor II, SO4 2- sensor.

[0018] Furthermore, the electrical automatic control system is provided with a PLC control box and a computer which are connected in sequence.

[0019] Furthermore, the sulfur-containing biological filler is inoculated with sulfur autotrophic denitrification functional bacteria, which can be commonly used bacteria in the art.

[0020] The present invention provides application of the above device in aquaculture wastewater treatment.

[0021] The present invention provides a method for efficiently treating aquaculture wastewater by deeply coupling sulfur autotrophic denitrification through a SND-AO process, and the aquaculture wastewater is treated by using the above-mentioned device.

[0022] Furthermore, when the device is in operation, the DO content in the SND pool is controlled to be 0.3-0.5 mg / L, the ORP is -50-+50 mv, the pH is 6.5-8.5, and the hydraulic retention time is 3-4 d; the DO in the A pool is controlled to be less than 0.1 mg / L, the ORP is -120--160 mv, and the hydraulic retention time is 1-2 d; the DO in the wastewater overflowing into the O pool is controlled between 2.0-3.0 mg / L, and the hydraulic retention time is 0.5-1 d; the mixed liquor in the O pool is pumped back to the SND pool and the A pool through the reflux port, and the reflux ratios are set to 300% and 100%, respectively; the mixed liquor in the A pool and the O pool is pumped into the bottom water distribution space of the SAD reactor, the hydraulic retention time is set to 0.2-0.3 d, the mixed liquor reflux ratio is controlled according to the S / N ratio of 1.3, and the device is operated continuously for 24 hours.

[0023] Furthermore, the operating flux of the membrane assembly in the O pool is 12 to 15 LMH, and water is pumped out intermittently, pumping for 8 to 9 minutes and stopping for 1 to 2 minutes.

[0024] Preferably, the membrane assembly is provided with automatic cleaning, the cleaning cycle is 5 to 10 days, and the cleaning time is 20 to 30 minutes; the online cleaning is performed with 0.2 g / L sodium hypochlorite, and the system stops running during cleaning.

[0025] The present invention has the following beneficial effects:

[0026] (1) The present invention breaks through the bottleneck of existing aquaculture wastewater treatment technology. Through the deep coupling of synchronous short-range nitrification and denitrification (SND) and sulfur autotrophic denitrification (SAD), the multi-organism synergistic effect of carbon source and sulfur source and the self-circulation of SND-AO-SAD are realized, and at the same time, the internal circulation of OA / SND and OA / SAD-A can be completed; through the circulation reflux, close material exchange is realized, and the design of segmented deep coupling avoids the risk of affecting its stability due to fluctuations in the external environment (such as pH, dissolved oxygen and electron donor concentration, etc.). Under such a design, the device of the present invention realizes the efficient removal of nitrogen, sulfur and organic pollutants in aquaculture wastewater and the recycling of sulfur, which significantly improves the operating stability, treatment effect and economy of the system, and is particularly suitable for the efficient treatment of complex pollutants in aquaculture wastewater.

[0027] (2) Through the coupling between pool A and SAD zone, the hydrogen sulfide produced in pool A is reacted with S 2- Recycling to the SAD reactor reduces sulfur waste and avoids SO4 2- Accumulated pollution problems. At the same time, aeration flushing can also prevent the aging of the biofilm of SAD biological filler, further improving the stability and efficiency of the system.

[0028] (3) The device and method of the present invention are used to deeply denitrify aquaculture wastewater. No additional carbon source needs to be added during the whole process, which effectively reduces the system sludge production and wastewater treatment costs. Precise micro-aeration control is used to reduce system energy consumption. The entire device has a compact structure, can treat aquaculture wastewater on a large scale, has low operating costs, and has a more efficient process economy, meeting the requirements of energy conservation and emission reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a cross-sectional structural diagram of a device for efficiently treating aquaculture wastewater by deeply coupling sulfur autotrophic denitrification using the SND-AO process.

[0030] Figure 2 This is a top view of the device body of Example 1.

[0031] Figure 3 This is a schematic diagram of the process of treating aquaculture wastewater using the device in Example 1.

[0032] The following are marked in the figure: aquaculture wastewater tank-1, lifting pump-1.1, solenoid valve-1.2, flow meter-1.3, SND tank-2, water inlet Ⅰ-2.1, mud valve-2.2, aeration fan-2.3, agitator Ⅰ-2.4, aeration plate Ⅰ-2.5, overflow port Ⅰ-2.6, pH sensor-2.7, DO sensor Ⅰ-2.8, ORP sensor Ⅰ-2.9, MLSS sensor-2.10, NH4 + -N sensor-2.11, NO2 - -N sensorⅠ-2.12, NO3 - -N sensor Ⅰ-2.13, reflux port Ⅰ-2.14, A pool-3, agitator Ⅱ-3.1, overflow port Ⅱ-3.2, gas outlet Ⅰ-3.3, reflux port Ⅱ-3.4, reflux port Ⅲ-3.5, H2S gas sensor Ⅰ-3.6, ORP sensor Ⅱ-3.7, DO sensor Ⅱ-3.8, S 2- Sensor Ⅰ-3.9, water outlet-3.10, vortex fan-3.11, O tank-4, agitator Ⅲ-4.1, aeration plate Ⅱ-4.2, reflux port Ⅳ-4.3, suction pump-4.4, membrane assembly-4.5, liquid level sensor-4.6, DO sensor Ⅲ-4.7, NO3 - -N sensor Ⅱ-4.8, sulfur autotrophic denitrification-SAD reactor-5, sulfur-containing biological filler-5.1, gas distribution plate-5.2, water inlet Ⅱ-5.3, gas outlet Ⅱ-5.4, reflux port Ⅴ-5.5, positive and negative pressure protector-5.6, H2S gas sensor Ⅱ-5.7, NO2 - -N sensor Ⅱ-5.8, NO3 - -N sensor Ⅲ-5.9, S 2- Sensor II-5.10, SO4 2-Sensor-5.11, one-way valve-5.12, water outlet tank-6, electrical automatic control system-7, PLC control box-7.1, computer-7.2. DETAILED DESCRIPTION

[0033] The present invention is further described below in conjunction with the accompanying drawings and specific examples, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0034] Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0035] Example 1

[0036] A device for treating aquaculture wastewater by deep coupling of SND-AO process with sulfur autotrophic denitrification and high efficiency, the cross-sectional structure diagram of the device is as follows Figure 1 As shown, it includes an aquaculture wastewater tank 1, a SND-AO system, a sulfur autotrophic denitrification-SAD reactor 5, a water outlet tank 6, and an electrical automatic control system 7 which are connected in sequence.

[0037] The SND-AO system includes the adjacently arranged SND pool 2, A pool 3, and O pool 4; wherein the SND pool 2 is provided with a water inlet Ⅰ2.1, a mud discharge valve 2.2, an aeration fan 2.3, an agitator Ⅰ2.4, an aeration plate Ⅰ2.5, an overflow port Ⅰ2.6, a sensor assembly Ⅰ (pH sensor 2.7, DO sensor Ⅰ2.8, ORP sensor Ⅰ2.9, MLSS sensor 2.10, NH4 + -N sensor 2.11, NO2 - -N sensorⅠ2.12, NO3 - -N sensor Ⅰ2.13), return port Ⅰ2.14; mud discharge valve 2.2 and aeration plate Ⅰ2.5 are arranged at the bottom of SND tank 2, aeration plate Ⅰ2.5 is connected to aeration fan 2.3, and wastewater enters A tank 3 through overflow port Ⅰ2.6.

[0038] Pool A 3 is a closed pool, in which there are agitator II 3.1, overflow port II 3.2, gas outlet I 3.3, reflux port II 3.4, reflux port III 3.5, sensor assembly II (H2S gas sensor I 3.6, ORP sensor II 3.7, DO sensor II 3.8, S 2-sensor Ⅰ3.9), water outlet 3.10; overflow port Ⅱ3.2 is arranged on a side close to the O tank 4 and opposite to the overflow port Ⅰ2.6; the air outlet Ⅰ3.3 is arranged at the top of the A tank 3 and connected to the vortex fan 3.11, the reflux port Ⅱ3.4 is connected to the reflux port Ⅴ5.5 of the sulfur autotrophic denitrification-SAD reactor 5, the water outlet 3.10 is connected to the water inlet Ⅱ5.3 of the sulfur autotrophic denitrification-SAD reactor 5, and the wastewater enters the O tank 4 through the overflow port Ⅱ3.2.

[0039] The O tank 4 is provided with a stirrer III 4.1, an aeration plate II 4.2, a reflux port IV 4.3, a suction pump 4.4, a membrane assembly 4.5, a liquid level sensor 4.6, a sensor assembly III (DO sensor III 4.7, NO3 - -N sensor II 4.8); an aeration plate II 4.2 is arranged at the bottom of the O tank 4 and connected to the aeration fan 2.3, and a membrane assembly 4.5 is connected to a suction pump 4.4 and a water outlet tank 6 in sequence.

[0040] The sulfur autotrophic denitrification-SAD reactor 5 is provided with sulfur-containing biological filler 5.1, gas distribution plate 5.2, water inlet II 5.3, gas outlet II 5.4, reflux port V 5.5, positive and negative pressure protector 5.6, sensor assembly IV (H2S gas sensor II 5.7, NO2 - -N sensor Ⅱ5.8, NO3 - -N sensor Ⅲ5.9, S 2- Sensor II 5.10, SO4 2- sensor 5.11), one-way valve 5.12; the air distribution plate 5.2 and the water inlet II 5.3 are arranged at the bottom of the SAD reactor, the positive and negative pressure protector 5.6 is arranged at the top of the SAD reactor, and the air outlet II 5.4 is connected to the vortex fan 3.11 through the one-way valve 5.12.

[0041] The reflux port IV4.3 of the O pool 4 is connected to the reflux port I2.14, the reflux port II3.5 and the water inlet II5.3 in sequence; the aquaculture wastewater tank 1 is provided with a lifting pump 1.1, a solenoid valve 1.2 and a flow meter 1.3 which are connected in sequence and are connected to the water inlet 2.1 of the SND pool 2.

[0042] The electrical automatic control system 7 is provided with a PLC control box 7.1 and a computer 7.2 which are connected in sequence. The electrical automatic control system 7 is electrically connected to the aquaculture wastewater tank 1, the SND-AO system, and the sulfur autotrophic denitrification-SAD reactor 5; wherein the electrical automatic control system 7 is electrically connected to the aquaculture wastewater tank 1, the aeration fan 2.3, the agitator I 2.4, the agitator II 3.1, the agitator III 4.1, the sensor components I to IV, the liquid level sensor 4.6, the membrane component 4.5, and the suction pump 4.4.

[0043] The top view of the experimental device is shown in Figure 2As shown, the device is centered on the sulfur autotrophic denitrification-SAD reactor 5, and is arranged in the form of concentric circles from the inside to the outside, and the O pool 4, the A pool 3, and the SND pool 2 are arranged. The SND internal circulation requires a larger reflux ratio. The circular design is conducive to the self-circulation of the SND area, and the wastewater is used to flow inertia in the concentric circles and enter the next stage of reaction through overflow. This reasonable arrangement can save energy. Secondly, the wastewater is in an arc flow state in the concentric circles, which reduces the reaction dead corners, is conducive to the homogenization of the incoming water, and accelerates the reflux cycle. It can also be set according to actual needs.

[0044] During treatment, the wastewater in the aquaculture wastewater tank 1 is connected to the water inlet Ⅰ2.1 of the SND pool 2 in the SND-AO system by the lifting pump 1.1 through the solenoid valve 1.2 and the flow meter 1.3, and circulates under the action of the stirrer Ⅰ2.4. The air enters the SND pool 2 through the aeration fan 2.3 and the aeration plate Ⅰ2.5 in turn, and undergoes a low-oxygen aeration reaction to enter synchronous short-range nitrification and denitrification. In this area, by precisely controlling the dissolved oxygen (DO less than 0.3 mg / L) and the redox potential (ORP of -50 to +50 mv), a suitable micro-oxygen environment is achieved, so that nitrifying bacteria and denitrifying bacteria coexist, and synchronous short-range nitrification and denitrification is achieved, thereby effectively removing organic matter (COD), ammonia nitrogen and total nitrogen (TN) in the aquaculture wastewater. The aquaculture wastewater treated by SND pool 2 enters pool A 3 through overflow port Ⅰ2.6 and is circulated and treated under the action of agitator Ⅱ3.1. Pool A provides a suitable sulfate reduction environment, enriches sulfate-reducing bacteria, and achieves the recycling of sulfur elements and reduces sulfate emissions. In order to ensure the smooth progress of this series of reactions, the redox potential (ORP) in pool A is controlled between -120 and -160mV. Nitrates and nitrites in the wastewater in pool A are reduced to nitrogen gas by denitrifying bacteria in an anaerobic environment, thereby further removing nitrogen from the wastewater. At the same time, the sulfur-derived gas H2S produced by the reaction is pumped into the bottom of the sulfur autotrophic denitrification-SAD reactor 5 through the gas outlet Ⅰ3.3 at the top under the action of the vortex fan 3.11 through the gas distribution plate 5.2, providing electron donors for sulfur autotrophic denitrification. If the H2S produced by the reaction in pool A is not completely absorbed by the SAD reactor, after detection by the sensor in the SAD reactor, the gas will be refluxed to pool A from the gas outlet II5.4 through the one-way valve 5.12 under the action of the vortex fan 3.11, and it is necessary to ensure that its concentration does not exceed the discharge standard; and when pool A is under negative pressure, the gas pressure in pool A can also be balanced through the gas outlet II5.4 pipeline of the SAD reactor.

[0045] The sensors installed in the device transmit the collected signals to the PLC control box 7.1 of the electrical automatic control system 7, and then feed them back to the computer 7.2 to continuously monitor the pH range, DO, ORP, NH4 + -N, NO2- -N、NO3 - -N、SO4 2- , S 2- The mass concentration of H2S is determined by pre-setting the control index range and making real-time parameter adjustments based on the monitoring data, such as the mixed liquor reflux ratio, membrane suction start and stop, etc., to control the synchronous short-range nitrification and denitrification and sulfur autotrophic denitrification process.

[0046] The wastewater after the reaction in pool A 3 enters pool O 4 through overflow port II 3.2. An oxidizing environment is provided in pool O 4 to convert ammonia nitrogen into nitrate nitrogen. Nitrate nitrogen can be used as the main removal object in SAD, and pool O 4 also has a certain removal effect on COD. It flows back to pool A and SND pool or SAD through the reflux port for circulation. Ammonia nitrogen and organic matter are further removed through ammonia oxidation and carbon oxidation reactions under aerobic conditions in pool O 4. At the same time, a membrane bioreactor (MBR) component is arranged in the O pool 4, which is started when the water is discharged after the final circulation treatment is completed to perform efficient mud-water separation, which can be used to intercept microorganisms, improve the system MLSS, and improve the water quality of the discharged water; the operation of the membrane component 4.5 is automatically controlled by the liquid level sensor 4.6, and when the liquid level is higher than the membrane component by 1.0m (which can be set according to actual needs), it starts to run, and after the reaction, the treated water is transported to the water outlet tank 6 by the suction pump 4.4 to complete the treatment of the aquaculture wastewater; when the upper liquid level is less than 0.1m, the water production pump stops running to prevent the water level from being too low and causing the membrane to suck empty.

[0047] The mixed liquor of aquaculture wastewater treated by the SND-AO system enters the bottom of the sulfur autotrophic denitrification-SAD reactor 5 from the reflux ports of pool A 3 and pool O 4 through the water inlet II 5.3 to react. A sulfur-containing biological filler 5.1 is provided inside the sulfur autotrophic denitrification-SAD reactor 5. The sulfur-containing biological carrier slowly releases sulfide as an electron donor, and strengthens the sulfur autotrophic denitrification through the hydrogen sulfide in the gas phase, while enriching sulfur autotrophic bacteria to achieve deep denitrification. At the same time, the hydrogen sulfide gas in pool A 3 is transported back to the SAD through the top outlet I 3.3 under the action of the vortex fan 3.11, providing an electron donor, strengthening the denitrification effect, and ensuring the stability of the system; after detection by the sensor, the nitrogen generated can be discharged by starting the positive and negative pressure protector 5.6 at the top of the sulfur autotrophic denitrification-SAD reactor 5. The wastewater treated by SAD (SO4 produced by SAD) 2- ) refluxes to the A pool 3 through the reflux port V5.5, reacts and decomposes into H2S or provides electron donors for SAD, and the cycle is repeated to reduce the waste of sulfur and reduce the content of by-product sulfate; after the reaction, it finally flows into the O pool 4, and finally passes through the membrane component 4.5 in the O pool 4 to improve the water quality of the effluent, and the suction pump 4.4 transports the membrane effluent to the outlet tank 6 to complete the aquaculture wastewater treatment.

[0048] In summary, the device of the present invention integrates four main areas: synchronous short-range nitrification and denitrification (SND pool), anaerobic pool (A pool), sulfur autotrophic denitrification pool (SAD pool) and aerobic pool (O pool). Through internal and external circulation in different areas, nitrogen, sulfur and organic pollutants are synergistically treated to achieve deep denitrification of wastewater and efficient recycling of resources. The flow chart of the device is as follows: Figure 3 As shown, the device of the present invention can realize the self-circulation of SND-AO-SAD, and can also complete the internal circulation of OA / SND and OA / SAD-A. The circulation reflux of the device can realize close material exchange, and the design of segmented deep coupling can avoid the risk of affecting its stability due to fluctuations in the external environment (such as pH, dissolved oxygen and electron donor concentration, etc.). Sulfate ions are reduced in pool A, and the hydrogen sulfide gas produced by the reaction is recycled to SAD. While ensuring sufficient electron donors in the sulfur autotrophic denitrification-SAD reactor, the removal of COD in the wastewater by pool A is enhanced, and the sulfate content in the effluent can be reduced. At the same time, the sulfate ions produced in SAD are recycled to pool A, and the sulfate ions are reduced to generate hydrogen sulfide in the gas phase and S in the liquid phase. 2- Sulfur autotrophic denitrification is enhanced to achieve deep nitrogen removal. The setting of material circulation flow realizes the mutual promotion of the two reactors.

[0049] Under such a design, the device of the present invention realizes the efficient removal of nitrogen, sulfur and organic pollutants in aquaculture wastewater and the recycling of sulfur, significantly improving the operational stability, treatment effect and economy of the system, and is particularly suitable for the efficient treatment of complex pollutants in aquaculture wastewater. The entire device system is compact, has low operating costs, low energy consumption and stable treatment effects, and realizes efficient deep denitrification treatment of aquaculture wastewater without the need for additional carbon sources. The present invention is based on the microenvironment theory of synchronous short-range nitrification and denitrification and sulfur autotrophic denitrification technology. Aquaculture wastewater is denitrified by a system of synchronous short-range nitrification and denitrification deep coupling with sulfur autotrophic denitrification. The system stability is ensured by means of PLC automatic control, membrane bioreactor and the like, achieving the goal of efficiently removing organic pollutants and nitrogen pollution in aquaculture wastewater by synchronous short-range nitrification and denitrification.

[0050] Example 2

[0051] The aquaculture wastewater from a breeding enterprise in Guangxi Zhuang Autonomous Region was treated after solid-liquid separation and phosphorus removal by adding chemicals. + -N mass concentration is 400-500 mg / L, TN mass concentration is 300-600 mg / L, COD concentration is 2000-3000 mg / L, and pH is 8.2. The device described in Implementation 1 is used for treatment, wherein the SND tank, A tank, and O tank (the membrane module is placed in the O tank) used in the SND-AO system for realizing synchronous short-range nitrification and denitrification have effective volumes of 20.94 m 3、9.6m 3 , 4.0m 3 The pilot reactor of sulfur autotrophic denitrification-SAD reactor has an effective volume of 3m 3 The sulfur autotrophic biofiller in the SAD reactor is 60% polyurethane sponge and 40% sulfur-containing filler. The density, porosity and specific surface area of ​​the composite material are 0.3-0.5 g / cm 3 ,15%~25%,100~150cm 2 / g.

[0052] 1. System startup

[0053] (1) Start-up of SND-AO system: Inoculate the sludge of traditional AO process into the system, adjust the system operating conditions to SND operating control conditions, and perform sludge acclimatization. The actual aquaculture wastewater inlet water quality is COD = 2000 ~ 3000 mg / L, NH4 + -N=300~500mg / L, TN=400~600mg / L. By controlling the frequency of the aeration fan, the aeration volume of the reactor is controlled. The DO (dissolved oxygen content) in the SND pool is preset to 0.3~0.5mg / L, the ORP (oxidation-reduction potential) is -50~+50mv, and the pH is 6.5-8.5. The DO of the anaerobic pool is controlled to be less than 0.1mg / L, the ORP is -120~-160mv, and the DO of the aerobic MBR pool (membrane bioreactor) is controlled between 2.0~3.0mg / L. The mixed liquor of the aerobic pool is returned to the SND pool, and the return ratio is set to 300%. The system MLSS (mixed liquor sludge concentration) is controlled at 6000-8000mg / L, and sludge is discharged regularly. The operating flux of the membrane module is 12-15LMH, intermittent water production, suction for 4 minutes, stop for 1 minute; automatic backwashing is adopted, the backwashing cycle is 5-10 days, and the backwashing time is 20-30 minutes. When the reactor is operated under this condition, when the MBR effluent NH4 + When -N is less than 2mg / L, COD concentration is less than 90mg / L, and TN mass concentration is less than 30mg / L, it indicates that the SND-AO system is successfully started.

[0054] (2) Startup of the sulfur autotrophic denitrification-SAD reactor: The reactor is equipped with a replaceable sulfur autotrophic denitrification biological carrier module. During the startup phase, sulfur autotrophic denitrification functional bacteria are inoculated, and sulfur-containing biological carriers are used to provide sulfur for sulfur autotrophic denitrification bacteria. 2- and use NO3 - -N concentration of 30mg / L aquaculture wastewater enters the SAD reactor for circulation, and sulfur autotrophic denitrifying bacteria are cultivated and domesticated. After 3 days of circulation, under the condition of continuous inflow and outflow, when the reactor effluent NO3 - When the -N concentration is less than 10 mg / L, it indicates that the sulfur autotrophic denitrification-SAD reactor is successfully started.

[0055] (3) Coupling and startup of the SND-AO system and the sulfur autotrophic denitrification-SAD reactor system: Connect the corresponding circulation pipes, turn on the vortex fan to realize gas circulation, and pass the SAD effluent into pool A to enrich sulfate-reducing bacteria for SO4 2- The mixed liquid of O pool was refluxed to SND pool and A pool, and the reflux ratio was controlled to be 300% and 100% respectively; the mixed liquid of A pool and O pool of SND-AO system was pumped into the bottom water distribution space of SAD reactor to supplement S 2- and NO3 - -N (from pool A and pool O, respectively), the mixed liquor reflux ratio is controlled according to the S:N ratio of 1.3, and the mixed gas containing H2S at the top of the anaerobic tank is introduced into the bottom of the SAD reactor through a vortex blower. When the H2S concentration at the top of the SAD reactor is higher than 0.03 mg / m 3 When the H2S concentration at the top is lower than 0.03 mg / m 3 When the gas circulation and sulfur recycling are started, the TN concentration of the outlet water is less than 10mg / L, indicating that the system has been successfully started.

[0056] 2. Operation after system startup

[0057] (1) The aquaculture wastewater is pumped into the SND-AO system through the lifting pump in the water tank. The complete operation process includes water intake, stirring, hypoxic aeration, circulation and reflux, and membrane water outlet. After mixing in the SND pool, the aeration fan frequency is controlled to control the aeration volume of the reactor, and the DO content in the SND pool is controlled to be 0.3-0.5 mg / L, ORP is -50-+50 mv, pH is 6.5-8.5, and the hydraulic retention time is 2-3 days. It flows into the anaerobic pool through the overflow, and the DO of the anaerobic pool is controlled to be less than 0.1 mg / L, ORP is -120--160 mv, and the hydraulic retention time is 1-2 days. The overflow enters the aerobic pool, and the DO is controlled between 2.0-3.0 mg / L, and the hydraulic retention time of the aerobic pool is 0.4-1 day. The mixed liquid of the aerobic pool is pumped back to the SND pool through the reflux port, and the reflux ratio is set to 300%. The aerobic pool is equipped with a membrane component, and its operation is automatically controlled by a liquid level sensor. When the liquid level is 1.0m higher than the membrane component, it starts to run. When the upper liquid level is less than 0.1m, the water production pump stops running. The operating flux of the membrane component is 12-15LMH, and water is pumped out intermittently, pumping for 9 minutes and stopping for 1 minute; the membrane is cleaned automatically, with a cleaning cycle of 5-10 days and a cleaning time of 20-30 minutes. The agent used is 0.2g / L sodium hypochlorite for online cleaning. After the backwash is completed, the system automatically runs.

[0058] (2) The mixed liquor of pool A and pool O of the SND-AO system was pumped into the bottom water distribution space of the sulfur autotrophic denitrification-SAD reactor through the reflux pipeline, and the reflux ratio of the mixed liquor of pool O was controlled according to the S / N ratio of 1.3, and the operation was continuous for 24 hours; the sulfur autotrophic denitrification was enhanced by hydrogen sulfide in the gas phase, and the sulfur autotrophic denitrification in the sulfur autotrophic denitrification-SAD reactor was 1.3. 2- The concentration determines the replacement time of the filler module to ensure sufficient electron donors in the sulfur autotrophic denitrification-SAD reactor.

[0059] The actual aquaculture wastewater inlet water quality is COD = 2000 ~ 3000 mg / L, NH4 + -N=300~500mg / L、TN=400~600mg / L. Under this condition, after being treated by the device system, the final MBR effluent COD concentration is less than 90.0mg / L, NH4 + -N concentration is less than 2.0mg / L, TN mass concentration is less than 5.0mg / L, COD removal rate ≥97%, NH4 + -N removal rate ≥99%, TN removal rate ≥99%, the specific operation and treatment results of each link are shown in Table 1.

[0060] Comparative Example 1

[0061] The device for efficiently treating aquaculture wastewater by deep coupling of SND-AO process with sulfur autotrophic denitrification adopted in this comparative example is different from the device in Example 1 in that no sulfur circulation reflux and gas reuse treatment are performed, that is, the aquaculture wastewater is directly passed through the SND tank, A tank, O tank and sulfur autotrophic denitrification filter tank in sequence, and finally discharged from the sulfur autotrophic denitrification filter tank after treatment. The condition parameter settings of the device are the same as those in Example 2.

[0062] The treatment and operation results of different devices are shown in Table 1, which shows that the COD, ammonia nitrogen and total nitrogen are further removed by using the device in Example 1 to treat the aquaculture wastewater. The removal rates of ammonia nitrogen and TN in the effluent are ≥99%, and the SO4 2- The concentration is effectively reduced. Compared with the traditional denitrification process, the TN removal rate of this device is higher, and the device itself can reach alkalinity balance without the need to supplement alkalinity. After operation, the pH of the system does not fluctuate much, maintaining stable reaction conditions; compared with the ordinary two-stage AO system for aquaculture wastewater, the residence time is shorter, which improves the treatment efficiency; at the same time, the device ensures the efficient removal of TN in the wastewater without the need for additional carbon source addition, pH adjustment, and low aeration volume, reduces sulfur waste, and reduces the content of effluent by-products, effectively reducing the system sludge production and wastewater treatment costs. It has the advantages of compact structure, low operating cost, low energy consumption and stable treatment effect, and realizes the efficient deep denitrification treatment of aquaculture wastewater without the need for additional carbon source addition, simplifies the denitrification treatment process steps, and shows good engineering application potential.

[0063] Table 1 Operation results of the devices of Example 1 and Comparative Example 1

[0064]

[0065]

[0066] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A device for efficiently treating aquaculture wastewater by deep coupling of SND-AO process with sulfur autotrophic denitrification, characterized in that: It includes an aquaculture wastewater tank (1), a SND-AO system, a sulfur autotrophic denitrification-SAD reactor (5), a water outlet tank (6), and an electrical automatic control system (7) which are connected in sequence; The SND-AO system comprises: an SND pool (2), an A pool (3), and an O pool (4) which are arranged adjacently; The SND tank (2) is provided with a water inlet I (2.1), a mud discharge valve (2.2), an aeration fan (2.3), a stirrer I (2.4), an aeration plate I (2.5), an overflow port I (2.6), a sensor assembly I, and a return port I (2.14); the mud discharge valve I (2.2) and the aeration plate I (2.5) are arranged at the bottom of the SND tank (2), the aeration plate I (2.5) is connected to the aeration fan (2.3), and the wastewater enters the A tank (3) through the overflow port I (2.6); The A pool (3) is a closed pool, and is provided with a stirrer II (3.1), an overflow port II (3.2), an air outlet I (3.3), a reflux port II (3.4), a reflux port III (3.5), a sensor assembly II, and a water outlet (3.10); the overflow port II (3.2) is arranged on a side close to the O pool (4) and opposite to the overflow port I (2.6); the air outlet I (3.3) is arranged at the top of the A pool (3) and connected to a vortex fan (3.11); the reflux port II (3.4) is connected to a reflux port V (5.5) of a sulfur autotrophic denitrification-SAD reactor (5); the water outlet (3.10) is connected to a water inlet II (5.3) of the sulfur autotrophic denitrification-SAD reactor (5); and wastewater enters the O pool (4) through the overflow port II (3.2); An agitator III (4.1), an aeration plate II (4.2), a reflux port IV (4.3), a suction pump (4.4), a membrane assembly (4.5), a liquid level sensor (4.6), and a sensor assembly III are provided in the O tank (4); the aeration plate II (4.2) is provided at the bottom of the O tank (4) and connected to the aeration fan (2.3); the membrane assembly (4.5) is connected to the suction pump (4.4) and the water outlet tank (6) in sequence; The sulfur autotrophic denitrification-SAD reactor (5) is provided with a sulfur-containing biological filler (5.1), a gas distribution plate (5.2), a water inlet II (5.3), a gas outlet II (5.4), a reflux port V (5.5), a positive and negative pressure protector (5.6), a sensor component IV, and a one-way valve (5.12); the gas distribution plate (5.2) and the water inlet II (5.3) are arranged at the bottom, the positive and negative pressure protector (5.6) is arranged at the top, and the gas outlet II (5.4) is connected to the vortex fan (3.11) through the one-way valve (5.12); The reflux port IV (4.3) of the O tank (4) is connected to the reflux port I (2.14), the reflux port II (3.5), and the water inlet II (5.3) in sequence; The electrical automatic control system (7) is electrically connected to the aquaculture wastewater tank (1), the aeration fan (2.3), the stirrer I (2.4), the stirrer II (3.1), the stirrer III (4.1), the sensor components I to IV, the liquid level sensor (4.6), the membrane component (4.5), and the suction pump (4.4).

2. The device according to claim 1, characterized in that: The aquaculture wastewater tank (1) is provided with a lifting pump (1.1), a solenoid valve (1.2), and a flow meter (1.3) which are connected in sequence, and is connected to a water inlet (2.1) of the SND pool (2).

3. The device according to claim 1, characterized in that: The sensor assembly I in the SND pool (2) includes: pH sensor (2.7), DO sensor I (2.8), ORP sensor I (2.9), MLSS sensor (2.10), NH4 + -N sensor (2.11), NO2 - -N sensor Ⅰ(2.12), NO3 - -N sensor Ⅰ (2.13); sensor assembly Ⅱ in pool A (3) includes: H2S gas sensor Ⅰ (3.6), ORP sensor Ⅱ (3.7), DO sensor Ⅱ (3.8), S 2- Sensor I (3.9); sensor assembly III in O pool (4) includes: DO sensor III (4.7), NO3 - -N sensor II (4.8).

4. The device according to claim 1, characterized in that: The sensor assembly IV in the sulfur autotrophic denitrification-SAD reactor (5) includes: H2S gas sensor II (5.7), NO2 - -N sensor Ⅱ (5.8), NO3 - -N sensor Ⅲ (5.9), S 2- Sensor II (5.10), SO4 2- Sensor (5.11).

5. The device according to claim 1, characterized in that: The electric automatic control system (7) is provided with a PLC control box (7.1) and a computer (7.2) which are connected in sequence.

6. The device according to claim 1, characterized in that: Sulfur-containing biological filler (5.1) is inoculated with sulfur-autotrophic denitrifying functional bacteria.

7. Use of the device according to claim 1 in the treatment of aquaculture wastewater.

8. A method for efficiently treating aquaculture wastewater by deep coupling of SND-AO process with sulfur autotrophic denitrification, characterized in that: Aquaculture wastewater is treated by using the device described in any one of claims 1 to 6.

9. The method according to claim 8, characterized in that: When the device is in operation, the DO content in the SND pool is controlled to be 0.3-0.5 mg / L, the ORP is -50-+50 mv, the pH is 6.5-8.5, and the hydraulic retention time is 3-4 days; the DO in the A pool is controlled to be less than 0.1 mg / L, the ORP is -120--160 mv, and the hydraulic retention time is 1-2 days; the DO in the wastewater overflowing into the O pool is controlled between 2.0-3.0 mg / L, and the hydraulic retention time is 0.5-1 day; the mixed liquid in the O pool is pumped back to the SND pool and the A pool through the reflux port, and the reflux ratio is set to 300% and 100% respectively; the mixed liquid in the A pool and the O pool is pumped into the bottom water distribution space of the SAD reactor, the hydraulic retention time is set to 0.2-0.3 days, the mixed liquid reflux ratio is controlled according to the S / N ratio of 1.3, and it operates continuously for 24 hours.

10. The method according to claim 8 or 9, characterized in that: The operating flux of the membrane assembly in the O pool is 12-15LMH, and water is pumped out intermittently, pumping for 8-9 minutes and stopping for 1-2 minutes.

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