Sewage treatment system and method

Abstract

The invention discloses a sewage treatment system and method, belonging to the technical field of sewage treatment, comprising: a primary anaerobic reactor, a stripping and ammonia evaporation system, an electric reduction Fenton system, a secondary anaerobic reactor and an anaerobic ammonia oxidation system; the primary anaerobic reactor is used for three-phase separation of wastewater, biogas and microbial sludge, and converting degradable organic matter into biogas by anaerobic microorganisms; the stripping and ammonia evaporation system is used for synthesizing ammonium bicarbonate from ammonia nitrogen and carbon dioxide in the sewage separated by the primary anaerobic reactor; the electric reduction Fenton system is used for converting the chain-opening and ring-breaking of the refractory organic matter in the sewage treated by the stripping and ammonia evaporation system into microbially degradable organic matter; the anaerobic ammonia oxidation system is used for converting the remaining ammonia nitrogen and nitrate nitrogen in the sewage treated by the secondary anaerobic reactor into nitrogen; the invention does not generate carbon dioxide during the treatment process, can convert the organic matter in the sewage into high-value products, and realizes the resource utilization of organic matter and ammonia nitrogen.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and in particular to a sewage treatment system and method. Background Art

[0002] Climate change and the emergence of water, energy and resource crises have promoted the transformation of sewage treatment to a comprehensive resource recovery model, and achieving carbon neutrality has gradually become the development direction of future sewage treatment. The main pollutants in sewage are organic matter and ammonia nitrogen. At present, the mainstream sewage treatment process at home and abroad is the activated sludge process. This process occupies a large area, has high energy consumption, and has a large carbon emission, which is not suitable for the current carbon neutrality requirements.

[0003] Compared with the traditional aerobic activated sludge process, anaerobic digestion (AD) has lower energy demand and sludge production. The organic matter in the sewage can be recovered as energy in the form of methane, which is expected to achieve self-sufficiency in process operation energy consumption. Anaerobic membrane bioreactor (AnMBR) has gradually become a powerful technology for sewage treatment with its excellent effluent quality and high net production capacity potential. AnMBR can achieve complete separation of HRT and SRT in the reactor. Under short HRT conditions, sludge and suspended solids (SS) will be retained in the reactor by the membrane components, and the slow-growing anaerobic microorganisms can grow stably under long SRT conditions, maintaining a high sludge concentration in the reactor, thereby solving the shortcomings of the AD process in dealing with municipal sewage with low organic matter concentration, large temperature fluctuations and large treatment volume.

[0004] The main way to remove ammonia nitrogen from sewage is the traditional denitrification reaction, but its engineering application still has the problems of high energy consumption and difficulty in achieving low carbonization. Anaerobic ammonia oxidation (anammox) can use ammonia nitrogen as an electron donor and nitrite nitrogen as an electron acceptor under anaerobic conditions to achieve the simultaneous removal of ammonia nitrogen and nitrite nitrogen and generate nitrogen gas. Compared with the traditional nitrification and denitrification process, the new process based on anaerobic ammonia oxidation can effectively reduce aeration costs, reduce sludge production and the demand for organic carbon sources, and is an important development direction for biological denitrification of sewage in the future. Summary of the invention

[0005] The purpose of the present invention is to overcome the above technical deficiencies, propose a sewage treatment system and method, and solve the technical problems in the prior art.

[0006] In order to achieve the above technical purpose, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a sewage treatment system, comprising: a primary anaerobic reactor, a stripping ammonia evaporation system, an electro-reduction Fenton system, a secondary anaerobic reactor and an anaerobic ammonium oxidation system.

[0008] The primary anaerobic reactor, the stripping ammonia evaporation system, the electro-reduction Fenton system, the secondary anaerobic reactor and the anaerobic ammonium oxidation system are connected in sequence;

[0009] The primary anaerobic reactor is used to separate the three phases of wastewater, biogas and microbial sludge, and convert degradable organic matter into biogas through anaerobic microorganisms;

[0010] The stripping ammonia distillation system is used to synthesize ammonium bicarbonate from ammonia nitrogen and carbon dioxide in the sewage separated by the primary anaerobic reactor;

[0011] The electro-reduction Fenton system is used to convert the difficult-to-degrade organic matter in the sewage treated by the stripping and ammonia distillation system into organic matter that is easily degradable by microorganisms;

[0012] The secondary anaerobic reactor is used to perform anaerobic digestion on the organic matter after chain opening and ring breaking, and continue to convert the degradable organic matter into biogas through anaerobic microorganisms;

[0013] The anaerobic ammonium oxidation system is used to convert the remaining ammonia nitrogen and nitrate nitrogen in the sewage after treatment in the secondary anaerobic reactor into nitrogen gas.

[0014] In some embodiments, the primary anaerobic reactor and the secondary anaerobic reactor both include an anaerobic reaction unit, an anaerobic AnMBR membrane unit, and a biogas purification unit.

[0015] The anaerobic reaction unit is used to separate wastewater, biogas and microbial sludge into three phases, and the biogas outlet of the anaerobic reaction unit is connected to the biogas purification unit, and the wastewater outlet of the anaerobic reaction unit is connected to the anaerobic AnMBR membrane unit.

[0016] In some embodiments, the anaerobic reaction unit includes an anaerobic reaction tower, a three-phase separator, and a steam-water separator.

[0017] A first water inlet pipe is arranged below one side of the anaerobic reaction tower, and a first liquid level gauge is arranged on one side of the anaerobic reaction tower;

[0018] The three-phase separator is accommodated inside the anaerobic reaction tower. The three-phase separator includes two layers of herringbone baffles. The baffle angle is between 45° and 60°. The overlap of the two layers of herringbone baffles is 10 to 20 cm.

[0019] The steam-water separator is located above the three-phase separator and is connected to the anaerobic reaction tower. Pebbles are arranged inside the steam-water separator.

[0020] In some embodiments, an overflow weir is provided at a position corresponding to the top of the three-phase separator on one side of the anaerobic reaction tower, and a flushing pipe is provided at a position corresponding to the steam-water separator and the pebbles.

[0021] In some embodiments, the anaerobic AnMBR membrane unit includes a water collecting tank and a mud-water separation tank. The water collecting tank is connected to the sewage outlet of the anaerobic reaction unit through a first water production pipe. A diaphragm is provided inside the mud-water separation box, and one side of the mud-water separation box is connected to the water collecting tank through a first water inlet pump and a first circulation pump, and a second water production pipe is provided on the other side of the mud-water separation box. The mud-water separation box is also connected to the anaerobic reaction unit through a second circulation pump and a steam-water mixer, and one side of the steam-water mixer is connected to a steam pipe.

[0022] In some embodiments, the biogas purification unit includes a water seal tank and a biogas purification system.

[0023] The water seal tank is connected to the biogas outlet of the anaerobic reaction unit through a biogas production pipe. A first pressure gauge is arranged on the biogas production pipe. A water supply pipe and a second liquid level gauge connected thereto are arranged on the outer side of the water seal tank. A sewage pipe is arranged on the lower side of the water seal tank.

[0024] The biogas purification system is connected with the water seal tank through a connecting pipe, and a second pressure gauge is arranged on the connecting pipe.

[0025] In some embodiments, the stripping ammonia evaporation system includes an analytical reaction tower, a gas deammoniation tower, a condenser, a gas-liquid separator, an ammonia extraction mixer, an ammonia recovery tower, a slurry tank, a centrifuge and packaging equipment. The analytical reaction tower is connected to the primary anaerobic reactor, the gas deammoniation tower is connected to the analytical reaction tower and a saturated steam inlet is provided on one side of the gas deammoniation tower. The inlet of the condenser is connected to the analytical reaction tower, the water outlet and the gas outlet of the condenser are respectively connected to the gas-liquid separator and the ammonia extraction mixer, the gas-liquid separator is connected to the analytical reaction tower, the ammonia extraction mixer is connected to the ammonia recovery tower, and the outlet of the ammonia recovery tower is connected to the slurry tank, the centrifuge and the packaging equipment in sequence.

[0026] In some embodiments, the electro-reduction Fenton system includes a reaction box, two DC power supplies and a hydrogen peroxide storage tank. One side of the reaction box is connected to the stripping and ammonia distillation system through a second water inlet pipe, and a third water production pipe is provided on the other side of the reaction box. A first anode plate, a cathode plate and a second anode plate are arranged in sequence in the reaction box. The two DC power supplies are respectively connected to the first anode plate, the cathode plate and the second anode plate. The first anode plate includes an iron base plate, Q235B, 304 stainless steel or pig iron, etc., the second anode plate includes a titanium base plate, a ruthenium base plate, an iridium base plate or a platinum base plate, etc., the cathode plate includes graphite or graphite felt, etc., and the hydrogen peroxide storage tank is connected to the second water inlet pipe through a hydrogen peroxide dosing pump.

[0027] In some embodiments, the anaerobic ammonium oxidation system includes an anaerobic ammonium oxidation reaction tower and a water inlet tank, the water inlet tank is connected to the electro-reduction Fenton system, the anaerobic ammonium oxidation reaction tower is formed with a reaction chamber and a reflux chamber, granular sludge is arranged in the reaction chamber, the water inlet tank is connected to the reaction chamber of the reaction tower through a third water inlet pipe and a second water inlet pump, the reflux chamber is connected to the third water inlet pipe through a third circulation pump, and a fourth water production pipe is arranged on the upper side of the anaerobic ammonium oxidation reaction tower.

[0028] In a second aspect, the present invention further provides a sewage treatment method, which is applied to the sewage treatment system as described above, and the method comprises:

[0029] Separate wastewater, biogas and microbial sludge into three phases, and convert degradable organic matter into biogas through anaerobic microorganisms;

[0030] Synthesize ammonium bicarbonate from ammonia nitrogen and carbon dioxide in sewage separated by a primary anaerobic reactor;

[0031] The difficult-to-degrade organic matter in the sewage treated by the steam stripping and ammonia distillation system is converted into organic matter that is easily degradable by microorganisms by opening the chain and breaking the ring;

[0032] Anaerobic digestion is carried out on the organic matter after chain opening and ring breaking, and the degradable organic matter is further converted into biogas through anaerobic microorganisms;

[0033] The remaining ammonia nitrogen and nitrate nitrogen in the sewage after treatment in the secondary anaerobic reactor are converted into nitrogen gas.

[0034] Compared with the prior art, the beneficial effects of the present invention include:

[0035] 1. The primary anaerobic reactor can convert organic matter in sewage into high-value products. The electro-reduction Fenton system and the secondary anaerobic reactor can convert difficult-to-degrade organic matter into easily degradable organic matter, and then the degradable organic matter can be converted into biogas, thus realizing the resource utilization of organic matter.

[0036] 2. The steam stripping and ammonia evaporation system can transform ammonia nitrogen in sewage into high-value products, turning sewage into treasure;

[0037] 3. The treatment process of the primary anaerobic reactor and the secondary anaerobic reactor adopts anaerobic microbial technology, which has low energy consumption and belongs to sustainable development technology. The use of the electro-reduction Fenton system can reduce the amount of iron sludge by 40%, thus reducing the operating cost;

[0038] No carbon dioxide is produced during the entire treatment process, which meets the carbon neutrality requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a treatment process flow chart of an embodiment of a sewage treatment system provided by the present invention;

[0040] Figure 2 It is a structural schematic diagram of a primary anaerobic reactor and a secondary anaerobic reactor of a sewage treatment system provided by the present invention;

[0041] Figure 3 It is a process flow chart of the steam stripping and ammonia distillation system of the sewage treatment system provided by the present invention;

[0042] Figure 4 It is a structural schematic diagram of the electro-reduction Fenton system of the sewage treatment system provided by the present invention;

[0043] Figure 5 It is a structural schematic diagram of the anaerobic ammonium oxidation system of the sewage treatment system provided by the present invention;

[0044] Figure 6 is a flow chart of the sewage treatment method provided by the present invention;

[0045] Figure 7 yes Figure 4 A basic schematic diagram of an electro-reduction Fenton system of a sewage treatment system and method;

[0046] Figure 8 yes Figure 1 Table of pollutant removal and degradation in sewage treatment systems.

[0047] In the figure:

[0048] 1. Primary anaerobic reactor;

[0049] 11. anaerobic reaction unit; 111. anaerobic reaction tower; 112. three-phase separator; 113. steam-water separator; 114. first water inlet pipe; 115. first liquid level gauge; 116. overflow weir; 117. gas collecting hood; 118. cleaning pipe;

[0050] 12. Anaerobic AnMBR membrane unit; 121. Water collecting tank; 1211. First water production pipe; 122. Mud-water separation tank; 123. Diaphragm; 124. First water inlet pump; 125. First circulation pump; 126. Second water production pipe; 127. Second circulation pump; 128. Soda-water mixer; 129. Steam pipe;

[0051] 13. Biogas purification unit; 131. Water seal tank; 132. Biogas purification system; 133. First pressure gauge; 134. Water supply pipe; 135. Second liquid level gauge; 136. Drain pipe; 137. Connecting pipe; 138. Second pressure gauge;

[0052] 2. Steam stripping ammonia evaporation system; 21. Analytical reaction tower; 22. Gas deammonification tower; 23. Condenser; 24. Gas-liquid separator; 25. Ammonia extraction mixer; 26. Ammonia recovery tower; 27. Crystal slurry tank; 28. Centrifuge; 29. ​​Packaging equipment;

[0053] 3. Electro-reduction Fenton system; 31. Reaction box; 32. DC power supply; 33. Hydrogen peroxide storage tank; 34. Second water inlet pipe; 35. Third water production pipe; 36. First anode plate; 37. Cathode plate; 38. Hydrogen peroxide dosing pump; 39. Second anode iron;

[0054] 4. Secondary anaerobic reactor;

[0055] 5. Anaerobic ammonium oxidation system; 51. Anaerobic ammonium oxidation reaction tower; 511. Reaction chamber; 512. Reflux chamber; 52. Water inlet tank; 53. Third water inlet pipe; 54. Second water inlet pump; 55. Third circulation pump; 56. Fourth water production pipe; 57. Aeration fan. DETAILED DESCRIPTION

[0056] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0057] The present invention provides a sewage treatment system and method, which are described below respectively.

[0058] like Figures 1 to 5 As shown, a specific embodiment of the present invention discloses a sewage treatment system, including: a primary anaerobic reactor 1, a stripping ammonia evaporation system 2, an electro-reduction Fenton system 3, a secondary anaerobic reactor 4 and an anaerobic ammonia oxidation system 5.

[0059] The primary anaerobic reactor 1, the stripping ammonia evaporation system 2, the electro-reduction Fenton system 3, the secondary anaerobic reactor 4 and the anaerobic ammonium oxidation system 5 are connected in sequence.

[0060] The primary anaerobic reactor 1 is used to separate the three phases of wastewater, biogas and microbial sludge, and convert degradable organic matter into biogas through anaerobic microorganisms.

[0061] The stripping ammonia evaporation system 2 is used to synthesize ammonium bicarbonate from ammonia nitrogen and carbon dioxide in the sewage separated by the primary anaerobic reactor 1.

[0062] The electro-reduction Fenton system 3 is used to convert the difficult-to-degrade organic matter in the sewage treated by the stripping and ammonia evaporation system 2 into organic matter that is easily degradable by microorganisms.

[0063] The secondary anaerobic reactor 4 is used to perform anaerobic digestion reaction on the organic matter after chain opening and ring breaking, and continue to convert the degradable organic matter into biogas through anaerobic microorganisms.

[0064] The anaerobic ammonium oxidation system 5 is used to convert the remaining ammonia nitrogen and nitrate nitrogen in the sewage after being treated by the secondary anaerobic reactor 4 into nitrogen gas.

[0065] In this sewage treatment system, sewage first enters the primary anaerobic reactor 1, where anaerobic microorganisms convert degradable organic matter into biogas. The biogas is purified and reused or incinerated to generate electricity. The produced water enters the stripping and ammonia distillation system 2, where ammonia nitrogen and carbon dioxide in the sewage are synthesized into ammonium bicarbonate. The sewage then enters the electro-reduction Fenton system 3 to open the chain and break the ring of the difficult-to-degrade organic matter, converting it into organic matter that is easily degradable by microorganisms. The sewage then enters the secondary anaerobic reactor 4, where the organic matter is further converted into biogas, thereby realizing the resource utilization of the organic matter. The sewage finally enters the anaerobic ammonia oxidation system 5 to convert the remaining ammonia nitrogen and nitrate nitrogen into nitrogen gas. The entire treatment process does not produce carbon dioxide, thereby realizing the resource utilization of organic matter and ammonia nitrogen.

[0066] like Figure 2 As shown, in some embodiments, the primary anaerobic reactor 1 and the secondary anaerobic reactor 4 both include an anaerobic reaction unit 11 , an anaerobic AnMBR membrane unit 12 and a biogas purification unit 13 .

[0067] The anaerobic reaction unit 11 is used to separate wastewater, biogas and microbial sludge into three phases, and the biogas outlet of the anaerobic reaction unit 11 is connected to the biogas purification unit 13 , and the wastewater outlet of the anaerobic reaction unit 11 is connected to the anaerobic AnMBR membrane unit 12 .

[0068] Specifically, the anaerobic reaction unit 11 includes an anaerobic reaction tower 111 , a three-phase separator 112 and a steam-water separator 113 .

[0069] A first water inlet pipe 114 is provided below one side of the anaerobic reaction tower 111, and a first liquid level gauge 115 is provided on one side of the anaerobic reaction tower 111. The countercurrent upflow anaerobic reaction tower 111 is adopted, and water enters from the first water inlet pipe 114 at the bottom of the equipment, and produced water is discharged from the top of the equipment.

[0070] The three-phase separator 112 is accommodated in the interior of the anaerobic reaction tower 111. The wastewater, biogas and microbial sludge are separated into three phases at the top of the reactor during the rising process to achieve separation of the three. The three-phase separator 112 adopts two layers of herringbone baffles with an angle of 45° to 60°. The overlapping part of the two layers of herringbone baffles is 10 to 20 cm. A gas collecting hood 117 is arranged on the top to collect biogas.

[0071] The steam-water separator 113 is located above the three-phase separator 112 and is connected to the anaerobic reaction tower 111. Pebbles are arranged inside the steam-water separator 113. Since the biogas carries part of the wastewater during the rising process, the steam-water separator 113 is arranged on the top of the anaerobic reaction tower 111. The wastewater is secondary separated in the steam-water separator 113 by gravity. By arranging pebbles on the upper part of the steam-water separator 113, the wastewater is further intercepted during the rising process. In addition, a cleaning pipe 118 is arranged on the upper part of the pebbles, and the flushing pipe is connected to the external water pipe. Water can be flushed to the pebbles in the steam-water separator 113 through the flushing pipe, and the pebbles are flushed regularly to avoid clogging by the pebbles.

[0072] Furthermore, the volume load of the anaerobic reaction tower 111 is 10-20 kgCOD / (m3d), the hydraulic load is 0.1-1 m3 / (m2 h), and the water distribution pipes in the anaerobic reaction tower 111 adopt a multi-use and multi-reserve mode, such as 10 for 10, 8 for 8, etc., and adopt a 45° downward slanted serpentine nozzle mode. At the same time, the main pipe is provided with equidistant water distribution holes of different apertures, so that the reactor is in a turbulent state, so that the microorganisms and wastewater are fully contacted, and the generated biogas mixes the system more fully from bottom to top.

[0073] Furthermore, in some embodiments, an overflow weir 116 is provided on one side of the anaerobic reaction tower 111 at a position corresponding to the top of the three-phase separator 112 . When the water level on the three-phase separator 112 is high, the water can be discharged through the overflow weir 116 .

[0074] Furthermore, in some embodiments, the effluent from the anaerobic reaction tower 111 enters the anaerobic AnMBR membrane unit 12, and the anaerobic AnMBR membrane unit 12 includes a water collecting tank 121 and a mud-water separation tank 122. The water collecting tank 121 is connected to the sewage outlet of the anaerobic reaction unit 11 through a first water production pipe 1211, and a diaphragm 123 is provided inside the mud-water separation tank 122. One side of the mud-water separation tank 122 is connected to the water collecting tank 121 through a first water inlet pump 124 and a first circulation pump 125, and a second water production pipe 126 is provided on the other side of the mud-water separation tank 122. The mud-water separation tank 122 is also connected to the anaerobic reaction unit 11 through a second circulation pump 127 and a soda-water mixer 128, so that the sewage in the anaerobic reaction tower 111 can enter the water collecting tank 121 through the first water production pipe 1211, and the sewage in the water collecting tank 121 is discharged through the first water inlet pump 124 and the first circulation pump 125. 124 and the first circulation pump 125 are pumped to one side of the diaphragm 123 in the mud-water separation box 122. The water is filtered through the diaphragm 123 and flows to the other side of the diaphragm 123, and finally discharged through the second water production pipe 126. The diaphragm 123 adopts an external tubular ultrafiltration membrane made of ceramic membrane or PVDF, and is equipped with a water inlet pump, a circulation pump, and a cleaning pump. The flux of the diaphragm 123 is 50-60L / h / m2, and the water flow rate of the diaphragm 123 is 2-3m / s. The diaphragm 123 is tilted, and a high-speed cross-flow method is used to reduce the clogging of the diaphragm 123. The produced water that passes through the diaphragm 123 enters the stripping and ammonia distillation system 2, and the sludge trapped on the diaphragm 123 returns to the anaerobic reaction tower 111 under the impact of the water flow of 2-3m / s, thereby ensuring that the sludge concentration in the anaerobic reaction tower 111 is maintained at a high operating condition, and the BOD removal rate is achieved above 95%.

[0075] At the same time, the circulating pump draws water from the top of the anaerobic reaction tower 111 and returns it to the bottom of the anaerobic reaction tower 111 to fully mix the entire system. The flow rate of the circulating pump is 5 to 10 times that of the inlet water. A steam pipe 129 is connected to one side of the steam-water mixer 128. Steam is supplied to the sewage through the steam-water mixer 128 to increase the temperature, ensuring that the reactor is maintained between 30 and 36°. The steam-water mixer 128 adopts the Venturi tube principle. The steam is at the throat position, and a negative pressure is formed through the sudden change of the pipeline to suck in the steam and fully mix it.

[0076] Furthermore, in some embodiments, the biogas purification unit 13 includes a water seal tank 131 and a biogas purification system 132 .

[0077] The water seal tank 131 is connected to the biogas outlet of the anaerobic reaction unit 11 through a biogas production pipe. A first pressure gauge 133 is provided on the biogas production pipe. A water supply pipe 134 and a second liquid level gauge 135 are respectively provided on the outside of the water seal tank 131. A sewage pipe 136 is provided on the lower side of the water seal tank 131.

[0078] The biogas purification system 132 is connected to the water seal tank 131 through a connecting pipe 137, and a second pressure gauge 138 is provided on the connecting pipe 137. The biogas from the steam-water separator 113 enters the water seal tank 131. The pressure of the gas collecting hood 117 in the anaerobic reaction tower 111 is adjusted by controlling the liquid level in the water seal tank 131 to ensure that a gas chamber is formed on the top of the three-phase separator 112, so as to better separate the gas, cement and three phases. After exiting the water seal tank 131, the biogas enters the biogas purification system 132, and enters the biogas power generation system or the biogas purification system after dehumidification, desulfurization and dust removal to realize the resource treatment of organic matter.

[0079] The principle of high-value products is anaerobic biological treatment. Organic matter generates methane and hydrogen under the action of anaerobic microorganisms. The specific process is divided into four stages:

[0080] (1) Hydrolysis stage: Due to their large molecular weight, high molecular weight organic matter cannot directly pass through the cell wall of anaerobic bacteria and needs to be decomposed into small molecules by extracellular enzymes outside the microorganism. Typical organic substances in wastewater, such as cellulose, are decomposed into cellobiose and glucose by cellulase, starch is decomposed into maltose and glucose, and protein is decomposed into short peptides and amino acids. After decomposition, these small molecules can pass through the cell wall and enter the body of the cell for the next step of decomposition.

[0081] (2) Acidification stage: The above-mentioned small molecular organic matter enters the cell body and is converted into simpler compounds and distributed outside the cell. The main product of this stage is volatile fatty acids (VFA), and some alcohols, lactic acid, carbon dioxide, hydrogen, ammonia, hydrogen sulfide and other products are also produced.

[0082] (3) Acetogenesis stage: In this stage, the product of the previous step is further converted into acetic acid, carbonic acid, hydrogen and new cellular substances.

[0083] (4) Methane production stage: In this stage, acetic acid, hydrogen, carbonic acid, formic acid and methanol are converted into methane, carbon dioxide and new cell substances. This stage is also the most important stage of the entire anaerobic process and the rate-limiting stage of the entire anaerobic reaction process.

[0084] After the sewage is treated by the primary anaerobic reactor 1, the organic matter is converted into small molecules such as methane, carbon dioxide, and ammonia nitrogen. Figure 3As shown, in some embodiments, the stripping ammonia evaporation system 2 includes an analytical reaction tower 21, a gas deammonification tower 22, a condenser 23, a gas-liquid separator 24, an ammonia extraction mixer 25, an ammonia recovery tower 26, a slurry tank 27, a centrifuge 28 and a packaging device 29. The outlet of the second water production pipe 126 provided on the mud-water separation box 122 is provided with a water collecting tank. The wastewater discharged from the mud-water separation box 122 can enter the water collecting tank through the second water production pipe 126. The water collecting tank is connected to the analytical reaction tower 21 through a preheater, so that the wastewater After being heated by the preheater, the wastewater enters the analytical reaction tower 21. The wastewater in the analytical reaction tower 21 flows into the interior of the gas deamination tower 22. The gas deamination tower 22 is connected to the analytical reaction tower 21 and a saturated steam inlet is provided on one side of the gas deamination tower 22. Saturated steam is introduced into the wastewater to increase the wastewater temperature. When the wastewater temperature reaches about 40°, the carbon dioxide in the wastewater begins to overflow. When the wastewater temperature reaches 60°, 80% of the carbon dioxide overflows from the wastewater. When the carbon dioxide is precipitated from the wastewater, the solution The pH value gradually rises from neutral to about 10.5, at which time the ammonia nitrogen in the sewage begins to precipitate, and saturated steam is continuously added to the sewage. When the sewage temperature reaches about 80°, 80% of the ammonia nitrogen in the sewage is precipitated; the inlet of the condenser 23 is connected to the analytical reaction tower 21, and the water outlet and the gas outlet of the condenser 23 are respectively connected to the gas-liquid separator 24 and the ammonia extraction mixer 25, and the gas-liquid separator 24 is connected to the analytical reaction tower 21, and the hydrocondensate in the ammonia is discharged back to the analytical reaction tower 21 for further reaction, and the ammonia extraction mixer 25 is further connected to the ammonia extraction mixer 25. The device 25 is connected to the ammonia recovery tower 26. The outlet of the ammonia recovery tower 26 is connected to the slurry tank 27, the centrifuge 28 and the packaging equipment 29 in sequence. One side of the ammonia recovery tower 26 is connected to a carbon dioxide tank. When the ammonia nitrogen concentration in the sewage is high, the system appropriately supplements carbon dioxide, and the carbon dioxide and ammonia nitrogen are pumped into the carbon-ammonia recovery tower 26 through the ammonia extraction mixer 25 and the vacuum pump. The slurry tank 27 and the centrifuge 28 convert the carbon dioxide and ammonia nitrogen in the sewage into ammonium bicarbonate, thereby realizing nitrogen resource utilization and carbon capture, and the packaging is carried out using the packaging equipment.

[0085] Furthermore, the wastewater outlet of the gas deammonification tower 22 is connected to the water outlet pool through a deep cooler, and the water outlet pool is connected to the reaction box 31 to facilitate further treatment of the wastewater; the ammonia recovery tower 26 is connected to a tail gas recovery tower to discharge the waste gas in the ammonia recovery tower 26 into the interior of the tail gas recovery tower, and the slurry tank 27, the centrifuge 28, the packaging equipment and the interior of the tail gas recovery tower are all connected to the induced draft fan, and the exhaust outlet of the induced draft fan is connected to the tail gas purification tower to realize the centralized collection and treatment of the waste gas.

[0086] The wastewater treated by the stripping and ammonia distillation system 2 still contains some organic matter that is difficult to degrade by microorganisms and 10-20% of ammonia nitrogen and total nitrogen, which need to be further treated, such as Figure 4 , Figure 7As shown, in some embodiments, the electro-reduction Fenton system 3 includes a reaction box 31, two DC power supplies 32 and a hydrogen peroxide storage tank 33. One side of the reaction box 31 is connected to the stripping and ammonia distillation system 2 through a second water inlet pipe 34, and the other side of the reaction box 31 is provided with a third water production pipe 35. The reaction box 31 is sequentially arranged with a first anode plate 36, a cathode plate 37 and a second anode plate 39. The two DC power supplies 32 are respectively connected to the first anode plate 36, the cathode plate 37 and the second anode plate 39, wherein the cathodes of the two DC power supplies 32 are connected to the cathode plate 37, the first anode plate 37 is arranged on the side close to the second water inlet pipe 34, and the second anode plate 39 is arranged on the side close to the third water production pipe 35. The hydrogen peroxide storage tank 33 is connected to the second water inlet pipe 34 through a hydrogen peroxide dosing pump 38. 4 are connected, the electro-reduction Fenton system 3 adopts a high-frequency low-voltage pulse power supply, and an oxidation zone, a precipitation zone and an internal reflux are set. After the reactants enter the reaction box 31, the macromolecular difficult-to-degrade organic matter is converted into organic matter that is easily degradable by microorganisms through OH. Under the DC power supply 32, the anode and the cathode are energized to generate an oxidation-reduction reaction. The zero-valent iron of the first anode plate 36 loses electrons and is converted into divalent iron. The divalent iron reacts with hydrogen peroxide in the sewage to generate OH and trivalent iron. The trivalent iron gains electrons at the cathode and is converted into divalent iron, which continues to participate in the Fenton reaction, realizing the recycling of iron ions and reducing the generation of iron mud. At the same time, the divalent iron is slowly released through the second anode plate 39, avoiding the reaction of excessive divalent iron with hydroxyl radicals, and improving the utilization efficiency of hydroxyl radicals. In addition, the side reactions such as anodic oxidation and cathode adsorption of pollutants in the electro-reduction Fenton system 3 can promote the treatment of pollutants. The first anode plate 36 is made of an iron substrate, Q235B, 304 stainless steel or pig iron, the second anode plate 39 is made of a titanium substrate, a ruthenium substrate, an iridium substrate or a platinum substrate, the cathode plate 37 is made of one of inert electrodes such as graphite, graphite felt, etc., the plate spacing is 2 to 3 cm, the current density is 10 to 40 mA / cm2, the reaction time is 10 to 30 min, and the mass addition ratio of hydrogen peroxide is 0.01 to 0.1%.

[0087] After electro-reduction Fenton oxidation, the sewage enters the secondary anaerobic reactor 4 to carry out anaerobic digestion reaction on the organic matter after chain breaking and ring breaking, further degrading the organic matter in the sewage. The volume load is 5-10 kgCOD / (m3d), the hydraulic load is 0.1-1m3 / (m2h), and the BOD removal rate is above 95%. The produced water enters the anaerobic ammonia oxidation system 5.

[0088] like Figure 5As shown, in some embodiments, the anaerobic ammonium oxidation system 5 includes an anaerobic ammonium oxidation reaction tower 51 and a water inlet tank 52, the water inlet tank 52 is connected to the third water production pipe 35 in the electro-reduction Fenton system 3, the anaerobic ammonium oxidation reaction tower 51 is formed with a reaction chamber 511 and a reflux chamber 512, and granular sludge is arranged in the reaction chamber 511. The water inlet tank 52 is connected to the reaction chamber 511 of the anaerobic ammonium oxidation reaction tower 51 through a third water inlet pipe 53 and a second water inlet pump 54, and the reflux chamber 512 is connected to the third water inlet pipe 53 through a third circulation pump 55. The upper side of the anaerobic ammonium oxidation reaction tower 51 is provided with a fourth water production pipe 56. The reactor adopts a short-cut nitrification-anaerobic ammonium oxidation (PN-ANAMMOX) integrated reactor system and a countercurrent upflow reactor. Under the action of the second water inlet pump 54, the water enters from the third water inlet pipe 53 at the bottom of the equipment and enters the reaction chamber 511 to flow upward. An aeration fan 57 is provided on the side corresponding to the anaerobic ammonium oxidation reaction tower 51 and the reaction chamber 511. By controlling the reaction conditions such as aeration amount and pH, synchronous short-cut nitrification-anaerobic ammonium oxidation and efficient nitrogen removal are achieved, with a total nitrogen load of 0.5-1.5 kg / (m3·d), a dissolved oxygen content of 0.1-1 mg / L, a pH of 7.8-9, and a reactor temperature of 35-37°. In addition, the divalent iron ions provided by the electro-reduction Fenton system 3 can significantly improve the activity of the anaerobic ammonium oxidation reaction in the anaerobic ammonium oxidation system 5. As the divalent iron concentration increases from 5 mg / L to 20 mg / L, the concentration of N2O in the gas production increases from 3 mg / L to 10 mg / L, and its average emission increases from 0.05% of the denitrification amount to 0.17%, and the denitrification efficiency increases by 12%. The anaerobic ammonium oxidation system 5 adopts a granular sludge method. Granular sludge is an aggregate of microorganisms. Compared with flocculent sludge, it has a larger particle size and good sedimentation performance, so it can retain more biomass and increase the nitrogen load of the influent. In addition, due to the special structure of the granular sludge, it has a certain resistance to changes in the influent water quality (nitrogen load, toxic and harmful substances, etc.). The produced water of the anaerobic ammonia oxidation reaction tower 51 flows to the reflux chamber 512, and the medium can be re-entered into the reaction chamber 511 through the reflux chamber 512 through the circulation pump, so as to realize the circulation reaction in the anaerobic ammonia oxidation reaction tower 51, and finally the sewage is discharged from the fourth water production pipe 56 at the top of the equipment.

[0089] When the COD and ammonia nitrogen concentrations of sewage are low, the membrane system can be added to concentrate it to high COD and high ammonia nitrogen sewage, and then the following methods can be used: Figure 8 The processing route described.

[0090] In order to better implement the sewage treatment system in the embodiment of the present invention, on the basis of the sewage treatment system, such as Figure 6 As shown, the present invention also provides a sewage treatment method, which is applied to the sewage treatment system as described above, and the method comprises:

[0091] S1, separate the wastewater, biogas and microbial sludge into three phases, and convert the degradable organic matter into biogas through anaerobic microorganisms;

[0092] S2, synthesizing ammonium bicarbonate from ammonia nitrogen and carbon dioxide in the sewage separated by the primary anaerobic reactor 1;

[0093] S3, converting the difficult-to-degrade organic matter in the sewage treated by the stripping and ammonia distillation system 2 into organic matter that is easily degradable by microorganisms;

[0094] S4, performing anaerobic digestion reaction on the organic matter after chain opening and ring breaking, and continuing to convert the degradable organic matter into biogas through anaerobic microorganisms;

[0095] S5. Convert the remaining ammonia nitrogen and nitrate nitrogen in the sewage after being treated by the secondary anaerobic reactor 4 into nitrogen gas.

[0096] The present invention also provides a more specific embodiment to illustrate the above steps S1 to S5:

[0097] Step 1, wastewater enters through the first water inlet pipe 114 at the bottom of the anaerobic reaction tower 111, and during the rising process, the three-phase separator 112 arranged at the top of the reactor separates the wastewater, biogas and microbial sludge into three phases. The biogas is purified by the steam-water separator 113 and enters the water seal tank 131 through the connecting pipe 137. After coming out of the water seal tank 131, the biogas enters the biogas purification system 132, and enters the biogas power generation system or the biogas purification system after dehumidification, desulfurization and dust removal. The wastewater after three-phase separation enters the water collecting tank 121 through the first water production pipe 1211, and the sewage in the water collecting tank 121 is pumped to one side of the diaphragm 123 in the mud-water separation tank 122 through the first water inlet pump 124 and the first circulation pump 125. The water is filtered through the diaphragm 123 and flows to the other side of the diaphragm 123, and the sludge in the wastewater is filtered again, and finally discharged through the second water production pipe 126;

[0098] Step 2: The wastewater is heated by the preheater through the second water production pipe 126 and then enters the analytical reaction tower 21. The wastewater in the analytical reaction tower 21 flows to the interior of the gas deammonification tower 22. Saturated steam is introduced into the sewage through the saturated steam inlet to precipitate the ammonia nitrogen in the sewage. The hydrocondensate in the ammonia is discharged back into the analytical reaction tower 21 by the condenser 23 and the gas-liquid separator 24 to continue the reaction. The carbon dioxide and ammonia nitrogen are pumped into the carbon-ammonia recovery tower 26 by the ammonia extraction mixer 25 and the vacuum pump. The slurry tank 27 and the centrifuge 28 convert the carbon dioxide and ammonia nitrogen in the sewage into ammonium bicarbonate to realize nitrogen resource utilization and carbon capture, and the wastewater is packaged by the packaging equipment.

[0099] Step 3: The treated wastewater flows to the reaction box 31 in the gas deamination tower 22, and the macromolecular refractory organic matter is converted into organic matter that is easily degradable by microorganisms through chain breaking and ring breaking by OH. Under the DC power supply 32, the anode and the cathode are energized to generate an oxidation-reduction reaction, and the zero-valent iron at the anode loses electrons and is converted into divalent iron. The divalent iron reacts with hydrogen peroxide in the sewage to generate OH and trivalent iron. The trivalent iron gains electrons at the cathode and is converted into divalent iron, and continues to participate in the Fenton reaction to achieve the recycling of iron ions.

[0100] Step 4: The sewage in the reaction box 31 enters the anaerobic reaction tower 111 in the secondary anaerobic reactor 4 through the third water production pipe 35, and repeats the process of step 1 to send the treated sewage to the anaerobic ammonium oxidation system 5 through the second water production pipe 126;

[0101] Step 5. Under the action of the second water inlet pump 54, water enters from the third water inlet pipe 53 at the bottom of the equipment, and enters the reaction chamber 511 and flows upward. An aeration fan 57 is provided on the side corresponding to the anaerobic ammonia oxidation reaction tower 51 and the reaction chamber 511. By controlling the reaction conditions such as aeration amount and pH, synchronous short-range nitrification and anaerobic ammonia oxidation high-efficiency denitrification are achieved. The produced water of the anaerobic ammonia oxidation reaction tower 51 flows to the reflux chamber 512, and the medium can be re-entered into the reaction chamber 511 through the reflux chamber 512 through the circulation pump, so as to realize the circulation reaction in the anaerobic ammonia oxidation reaction tower 51. Finally, the sewage is discharged from the fourth produced water pipe 56 at the top of the equipment.

[0102] The present invention has the following beneficial effects:

[0103] 1. Provide a sewage treatment method: "primary anaerobic AnMBR + stripping ammonia evaporation + electro-reduction Fenton + secondary anaerobic mnMBR + anaerobic ammonia oxidation". The primary anaerobic reactor 1 can convert organic matter in sewage into high-value products, and the electro-reduction Fenton system 3 and the secondary anaerobic reactor 4 can convert difficult-to-degrade organic matter into easily degradable organic matter, and then the degradable organic matter can be converted into biogas, so as to realize the resource utilization of organic matter.

[0104] 2. The stripping ammonia evaporation system 2 can transform the ammonia nitrogen in the sewage into high-value fertilizer, turning the sewage into treasure.

[0105] 3. No carbon dioxide is produced during the entire treatment process, which meets the carbon neutrality requirements.

[0106] 4. The treatment process of the primary anaerobic reactor 1 and the secondary anaerobic reactor 4 adopts anaerobic microbial technology, which has low energy consumption and belongs to sustainable development technology.

[0107] 5. The three-phase separator 112 in the primary anaerobic reactor 1 and the secondary anaerobic reactor 4 can separate the sludge in the sewage, so that the amount of sludge generated by the system is small, which can solve the current problem of difficult sludge disposal at the source.

[0108] 6. The electro-reduction Fenton technology can realize the recycling of iron ions, reduce the dosage of reagents and the amount of sludge produced, reduce the amount of iron sludge by 40%, and reduce the operating cost by 20%.

[0109] The specific implementation of the present invention described above does not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A sewage treatment system, characterized in that: include: Primary anaerobic reactor, stripping ammonia system, electro-reduction Fenton system, secondary anaerobic reactor and anaerobic ammonium oxidation system, The primary anaerobic reactor, the stripping ammonia evaporation system, the electro-reduction Fenton system, the secondary anaerobic reactor and the anaerobic ammonium oxidation system are connected in sequence; The primary anaerobic reactor is used to separate the wastewater, biogas and microbial sludge into three phases, and convert the degradable organic matter into biogas through anaerobic microorganisms; The stripping and ammonia distillation system is used to synthesize ammonium bicarbonate from ammonia nitrogen and carbon dioxide in the sewage separated by the primary anaerobic reactor; The electro-reduction Fenton system is used to convert the difficult-to-degrade organic matter in the sewage treated by the stripping and ammonia evaporation system into organic matter that is easily degradable by microorganisms; The secondary anaerobic reactor is used to perform anaerobic digestion on the organic matter after chain opening and ring breaking, and continue to convert the degradable organic matter into biogas through anaerobic microorganisms; The electro-reduction Fenton system comprises a reaction box, two direct current power supplies and a hydrogen peroxide storage tank. One side of the reaction box is connected to the stripping and ammonia distillation system through a second water inlet pipe. The other side of the reaction box is provided with a third water production pipe. A first anode plate, a cathode plate and a second anode plate are sequentially arranged in the reaction box. The two direct current power supplies are respectively connected to the first anode plate, the cathode plate and the second anode plate. The first anode plate comprises an iron substrate, Q235B, 304 stainless steel or pig iron. The second anode plate comprises a titanium substrate, a ruthenium substrate, an iridium substrate or a platinum substrate. The cathode plate comprises graphite or graphite felt. The hydrogen peroxide storage tank is connected to the second water inlet pipe through a hydrogen peroxide dosing pump. The anaerobic ammonium oxidation system is used to convert the remaining ammonia nitrogen and nitrate nitrogen in the sewage after being treated by the secondary anaerobic reactor into nitrogen gas; the anaerobic ammonium oxidation system includes an anaerobic ammonium oxidation reaction tower and a water inlet tank, the water inlet tank is connected to the electro-reduction Fenton system, the anaerobic ammonium oxidation reaction tower is formed with a reaction chamber and a reflux chamber, granular sludge is arranged in the reaction chamber, the water inlet tank is connected to the reaction chamber of the reaction tower through a third water inlet pipe and a second water inlet pump, the reflux chamber is connected to the third water inlet pipe through a third circulation pump, and a fourth water production pipe is arranged on the upper side of the anaerobic ammonium oxidation reaction tower; an aeration fan is arranged on the side corresponding to the reaction chamber of the anaerobic ammonium oxidation reaction tower, and synchronous short-range nitrification~anaerobic ammonium oxidation efficient denitrification is realized by controlling the aeration amount and pH reaction conditions.

2. A sewage treatment system according to claim 1, characterized in that: The primary anaerobic reactor and the secondary anaerobic reactor both include an anaerobic reaction unit, an anaerobic AnMBR membrane unit and a biogas purification unit. The anaerobic reaction unit is used to separate wastewater, biogas and microbial sludge into three phases, and the biogas outlet of the anaerobic reaction unit is connected to the biogas purification unit, and the wastewater outlet of the anaerobic reaction unit is connected to the anaerobic AnMBR membrane unit.

3. A sewage treatment system according to claim 2, characterized in that: The anaerobic reaction unit includes an anaerobic reaction tower, a three-phase separator and a steam-water separator. A first water inlet pipe is provided below one side of the anaerobic reaction tower, and a first liquid level gauge is provided on one side of the anaerobic reaction tower; The three-phase separator is accommodated inside the anaerobic reaction tower, and the three-phase separator includes two layers of herringbone baffles, the baffle angle is between 45° and 60°, and the overlap of the two layers of herringbone baffles is 10 to 20 cm; The steam-water separator is located above the three-phase separator and is in communication with the anaerobic reaction tower. Pebbles are arranged inside the steam-water separator.

4. A sewage treatment system according to claim 3, characterized in that: An overflow weir is provided at a position corresponding to the top of the three-phase separator on one side of the anaerobic reaction tower, and a flushing pipe is provided at a position corresponding to the steam-water separator and the pebbles.

5. A sewage treatment system according to claim 2, characterized in that: The anaerobic AnMBR membrane unit includes a water collecting tank and a mud-water separation tank. The water collecting tank is connected to the sewage outlet of the anaerobic reaction unit through a first water production pipe. A diaphragm is arranged inside the mud-water separation tank. One side of the mud-water separation tank is connected to the water collecting tank through a first water inlet pump and a first circulation pump. A second water production pipe is arranged on the other side of the mud-water separation tank. The mud-water separation tank is also connected to the anaerobic reaction unit through a second circulation pump and a steam-water mixer. One side of the steam-water mixer is connected to a steam pipe.

6. A sewage treatment system according to claim 2, characterized in that: The biogas purification unit includes a water seal tank and a biogas purification system. The water seal tank is connected to the biogas outlet of the anaerobic reaction unit through a biogas production pipe, a first pressure gauge is arranged on the biogas production pipe, a water supply pipe and a second liquid level gauge connected thereto are arranged on the outside of the water seal tank, and a sewage pipe is arranged on the lower side of the water seal tank; The biogas purification system is connected to the water seal tank through a connecting pipe, and a second pressure gauge is provided on the connecting pipe.

7. A sewage treatment system according to claim 1, characterized in that: The stripping ammonia evaporation system includes an analytical reaction tower, a gas deammoniation tower, a condenser, a gas-liquid separator, an ammonia extraction mixer, an ammonia recovery tower, a slurry tank, a centrifuge and packaging equipment. The analytical reaction tower is connected to the primary anaerobic reactor, the gas deammoniation tower is connected to the analytical reaction tower and a saturated steam inlet is provided on one side of the gas deammoniation tower. The inlet of the condenser is connected to the analytical reaction tower, the water outlet and the gas outlet of the condenser are respectively connected to the gas-liquid separator and the ammonia extraction mixer, the gas-liquid separator is connected to the analytical reaction tower, the ammonia extraction mixer is connected to the ammonia recovery tower, and the outlet of the ammonia recovery tower is connected to the slurry tank, the centrifuge and the packaging equipment in sequence.

8. A sewage treatment method, applied to the sewage treatment system according to any one of claims 1 to 7, characterized in that: The method comprises: Separate wastewater, biogas and microbial sludge into three phases, and convert degradable organic matter into biogas through anaerobic microorganisms; Synthesize ammonium bicarbonate from ammonia nitrogen and carbon dioxide in sewage separated by a primary anaerobic reactor; The difficult-to-degrade organic matter in the sewage treated by the steam stripping and ammonia distillation system is converted into organic matter that is easily degradable by microorganisms by opening the chain and breaking the ring; Anaerobic digestion is carried out on the organic matter after chain opening and ring breaking, and the degradable organic matter is further converted into biogas through anaerobic microorganisms; The remaining ammonia nitrogen and nitrate nitrogen in the sewage after treatment in the secondary anaerobic reactor are converted into nitrogen gas.

Images