High-concentration suspended organic wastewater treatment device and method capable of synchronously recovering carbon, nitrogen, phosphorus and hydrogen

Abstract

The invention discloses a high-concentration suspended organic wastewater treatment device and method capable of synchronously recovering carbon, nitrogen, phosphorus and hydrogen, and belongs to the technical field of high-concentration suspended organic wastewater treatment.The high-concentration suspended organic wastewater treatment device comprises a micro-electrolysis anaerobic dynamic membrane bioreactor system, an electrochemical struvite crystallization and precipitation system and an aerobic activated sludge degradation system, the micro-electrolysis anaerobic dynamic membrane bioreactor system is connected with the electrochemical struvite crystallization and precipitation system, and the electrochemical struvite crystallization and precipitation system is connected with the aerobic activated sludge degradation system. According to the high-concentration suspended organic wastewater treatment device and method capable of synchronously recovering carbon, nitrogen, phosphorus and hydrogen, the micro-electrolysis anaerobic dynamic membrane bioreactor system is used for efficiently removing most organic matters and partially converting the organic matters into methane to realize recycling; the electrochemical struvite crystallization and precipitation system converts most of ammonia nitrogen and phosphorus into struvite and generates hydrogen to realize recycling, and the aerobic activated sludge degradation system removes residual organic matters to realize up-to-standard discharge.

Description

Technical Field

[0001] The present invention relates to the technical field of high-concentration suspended organic wastewater treatment, and in particular to a high-concentration suspended organic wastewater treatment device and method capable of simultaneously recovering carbon, nitrogen, phosphorus and hydrogen. Background Art

[0002] Industries like livestock farming, biopharmaceuticals, and waste disposal generate large quantities of high-concentration wastewater rich in suspended organic matter and nitrogen and phosphorus nutrients. These high concentrations of organic matter, nitrogen, and phosphorus in wastewater are energy carriers, necessitating efficient treatment methods to reduce pollutant emissions while simultaneously recovering these resources and energy.

[0003] High-concentration suspended organic wastewater is usually first treated by anaerobic digestion to convert organic matter into carbon dioxide and methane that can be recycled for power generation, thereby achieving the removal and recycling of organic matter in the wastewater. However, the organic matter in high-concentration suspended organic wastewater mainly exists in the form of suspended matter (volatile suspended solids are as high as 20g / L, and COD accounts for as much as 80%). The slow dissolution / hydrolysis rate based on the microbial extracellular surface reaction mechanism has become the main bottleneck restricting its anaerobic digestion efficiency. On the one hand, high-concentration suspended matter leads to long hydraulic retention time, large floor space, and low COD removal and methane conversion efficiency in traditional completely mixed anaerobic digestion processes; on the other hand, it affects the formation of granular sludge, resulting in the need for high-intensity pretreatment to significantly reduce its concentration before high-load anaerobic digestion processes represented by upflow anaerobic sludge blankets can be directly applied, thereby significantly increasing treatment costs.

[0004] After high-concentration suspended organic wastewater is treated by anaerobic digestion + solid-liquid separation process, most of the suspended impurities and organic matter have been removed. The ammonium ions (containing ammonia nitrogen) and phosphate ions (containing phosphorus) retained in the effluent and the added magnesium ions will form struvite (i.e. magnesium ammonium phosphate) crystals under appropriate conditions and precipitate (Mg 2+ +NH4 + +H n PO4 3-n +6H2O→MgNH4PO4·6H2O↓+nH + ) and can be recycled. Struvite is a high-quality slow-release nitrogen and phosphorus compound fertilizer that is very suitable for crop cultivation and therefore has high economic value. A suitable alkaline environment and an appropriate amount of magnesium ions are necessary conditions for the formation of struvite. Directly adding sodium hydroxide and magnesium chloride to the effluent treated by anaerobic digestion + solid-liquid separation process is a common method, but the resulting struvite crystals are fine and difficult to separate and dehydrate by solid-liquid separation. In addition, the cost of adding the agent is also high.

[0005] After high-concentration suspended organic wastewater is treated by anaerobic digestion + solid-liquid separation and struvite precipitation, only a small amount of organic matter in the effluent needs to be removed to meet the discharge standards, and aerobic biological (activated sludge or biofilm) degradation is the most commonly used method to remove this part of organic matter. Summary of the Invention

[0006] The purpose of the present invention is to provide a high-concentration suspended organic wastewater treatment device and method that can simultaneously recover carbon, nitrogen, phosphorus and hydrogen. The micro-electrolysis anaerobic dynamic membrane bioreactor system can efficiently remove most of the organic matter in the wastewater and partially convert it into methane for recycling. The electrochemical struvite crystallization precipitation system can convert most of the ammonia nitrogen and orthophosphorus (i.e., phosphate phosphorus) in the wastewater into struvite and produce hydrogen for recycling. The aerobic activated sludge degradation system can remove residual organic matter in the wastewater to achieve standard discharge.

[0007] To achieve the above-mentioned objectives, the present invention provides a high-concentration suspended organic wastewater treatment device that can simultaneously recover carbon, nitrogen, phosphorus and hydrogen, including a micro-electrolysis anaerobic dynamic membrane bioreactor system, an electrochemical struvite crystallization precipitation system and an aerobic activated sludge degradation system. The micro-electrolysis anaerobic dynamic membrane bioreactor system is connected to the electrochemical struvite crystallization precipitation system, and the electrochemical struvite crystallization precipitation system is connected to the aerobic activated sludge degradation system.

[0008] Preferably, the micro-electrolysis anaerobic dynamic membrane bioreactor system includes an anaerobic tank, which is connected to the membrane tank through a mixed liquid circulation pump, and an overflow return pipe is provided between the anaerobic tank and the membrane tank. The membrane tank is connected to the electrochemical struvite crystallization precipitation system through a suction water pump.

[0009] Preferably, the anaerobic tank is connected to the biogas bag and the water inlet pump, and is also connected to the biogas circulation aeration fan and the cheap carbon electrode micro-electrolysis unit. A redox potentiometer is installed in the anaerobic tank, and the redox potentiometer and the cheap carbon electrode micro-electrolysis unit are both connected to the controller.

[0010] Preferably, a cheap micro-mesh filter membrane with a dynamic sludge layer attached to the surface is provided in the membrane pool, a sludge pump is installed at the bottom of the membrane pool, and the top of the membrane pool is connected to a biogas bag.

[0011] Preferably, the electrochemical struvite crystallization precipitation system includes a fluidized bed configuration electrolytic cell, the electrolytic cell is connected to a hydrogen bag, a struvite precipitation recovery component is installed at the bottom of the electrolytic cell, the electrolytic cell is connected to a suction water pump and a metering pump, and a supernatant overflow outlet pipe is provided above it.

[0012] Preferably, the aerobic activated sludge degradation system includes an aeration tank, the aeration tank is connected to a secondary sedimentation tank, the secondary sedimentation tank is connected to a return pump, and the other end of the return pump is connected to the aeration tank.

[0013] The present invention also provides a method for treating high-concentration suspended organic wastewater capable of simultaneously recovering carbon, nitrogen, phosphorus and hydrogen, which uses the above-mentioned high-concentration suspended organic wastewater treatment device capable of simultaneously recovering carbon, nitrogen, phosphorus and hydrogen, comprising the following steps:

[0014] Step 1: First, high-concentration suspended organic wastewater is transported to the anaerobic tank through the water inlet pump for anaerobic digestion treatment. At the same time, the anaerobic tank is kept uniformly mixed through aeration by the biogas circulation fan, and the inexpensive carbon electrode micro-electrolysis unit is controlled by the redox potentiometer to supply trace oxygen and hydrogen to the anaerobic tank. The treated anaerobic sludge mixture is then transported to the membrane tank through the mixed liquid circulation pump, and the inexpensive micro-mesh filter membrane with a dynamic sludge layer attached to the surface is used for mud and water separation. The remaining sludge is discharged through the sludge discharge pump, and the biogas is collected and utilized by the biogas bag;

[0015] Step 2: The effluent from the cheap micromesh filter in step 1 is sucked into the electrolytic cell through a suction water pump, and an appropriate amount of ammonium salt or phosphate is added to the electrolytic cell through a metering pump to match the molar ratio of ammonia nitrogen and phosphate phosphorus in the water to 1. The effluent from the suction water pump and the metering pump flows upward from the bottom of the electrode through the electrode plate area, and struvite crystals are generated near the anode and then precipitated to the bottom and collected and utilized by a recovery system. The refractory organic matter is oxidized near the cathode to generate hydrogen, which is collected and utilized by a hydrogen bag;

[0016] Step 3: The supernatant in step 2 is flowed into the aeration tank through the supernatant overflow outlet pipe. Aerobic activated sludge microorganisms use the oxygen provided by air aeration to decompose part of the residual organic matter in the wastewater into carbon dioxide and water, and part of it is used for microbial proliferation. The resulting mixed liquid is then passed into the secondary sedimentation tank for solid-liquid separation. The precipitated sludge is partially returned to the aeration tank to maintain the microbial concentration, and the remaining sludge is discharged from the system.

[0017] Preferably, in step 1, the micro-electrolysis unit uses cheap carbon brush electrodes, the electrode spacing is 1-3 cm, the electrode voltage is 1.2-2 V; the hydraulic retention time in the anaerobic tank is 1-5 days, the sludge retention time is 30-100 days, and the temperature is room temperature; the cheap micro-mesh filter flux is 5-15 L / m 2 / d; The micro-electrolysis unit automatically operates intermittently based on the fluctuation of the redox potential in the anaerobic tank between -400mV and -150mV.

[0018] Preferably, in step 2, the cathode of the electrolytic cell is a nickel-plated stainless steel plate or a platinum-plated carbon plate, the anode is a magnesium plate, the hydraulic retention time of the electrolytic cell is 1-5h, the electrode voltage is 1.5-3V, and the electrode spacing is 0.5-1.5cm.

[0019] Preferably, in step 3, the hydraulic retention time of the aeration tank is 6-24 hours, the sludge retention time is 10-20 days, and the dissolved oxygen is not less than 2 mg / L.

[0020] Anaerobic dynamic membrane bioreactor processes, which utilize inexpensive micromesh membranes, such as non-woven fabrics, to replace the gravity sedimentation coupled with traditional anaerobic digestion processes, offer potential technical advantages for treating high-concentration suspended organic wastewater. These inexpensive micromesh membranes, with a dynamic sludge layer attached to their surfaces, offer similar filtration accuracy to microfiltration / ultrafiltration membranes, completely intercepting anaerobic sludge flocs, efficiently intercepting suspended organic matter, and partially intercepting macromolecular organic matter. This achieves a complete separation between hydraulic retention time (HRT) and sludge retention time (SRT), enabling efficient anaerobic digestion with short HRT and long SRT (high COD removal and methane conversion rates, low effluent COD, and low excess sludge production). Furthermore, this extends the residence time of suspended and macromolecular organic matter (i.e., the time they spend reacting with anaerobic microorganisms), partially separating them from the HRT and enhancing their degradation, conversion, and methane production. Furthermore, these inexpensive micromesh membranes are significantly less expensive than the microfiltration / ultrafiltration membranes used in traditional anaerobic membrane bioreactors, offering significant cost advantages. Providing trace amounts of oxygen and hydrogen to an anaerobic dynamic membrane bioreactor system through microelectrolysis using inexpensive carbon electrodes offers the following advantages: 1) Trace oxygen enhances the metabolic activity of hydrolytic bacteria, thereby increasing the solubility / hydrolysis rate of suspended and macromolecular organic matter and promoting methanogenesis; 2) Trace oxygen removes hydrogen sulfide from biogas, reducing the cost of subsequent biogas utilization; 3) Trace oxygen promotes the agglomeration of anaerobic sludge flocs, thereby improving the filtration performance of the anaerobic sludge mixed liquor; 4) Trace hydrogen promotes the reduction of carbon dioxide to methane, thereby increasing the methane content in biogas; and 5) Inexpensive carbon electrodes offer significant cost advantages over conventional metal electrodes for water electrolysis. Therefore, the microelectrolysis anaerobic dynamic membrane bioreactor process for treating high-concentration suspended organic wastewater can significantly improve organic matter removal, methane recovery, and membrane filtration efficiency.

[0021] The effluent from the micro-electrolysis anaerobic dynamic membrane bioreactor system is electrolyzed using a magnesium anode and an inert cathode to provide magnesium ions and hydroxide ions to generate struvite. This process has many advantages, including the fact that struvite preferentially deposits near the anode, making it easy to separate and dehydrate; there is no interference from suspended matter in the water, resulting in high-purity struvite; it can oxidize some difficult-to-degrade organic matter, thereby reducing subsequent processing costs; it can utilize renewable electricity such as wind power and photovoltaics, thereby reducing costs; and it can produce hydrogen, a high-value byproduct, thereby further increasing profits and reducing costs.

[0022] After high-concentration suspended organic wastewater is treated by a micro-electrolysis anaerobic dynamic membrane bioreactor system combined with an electrochemical struvite crystallization precipitation system, only a small amount of organic matter needs to be removed from the effluent to meet emission standards. Aerobic activated sludge degradation is the most economical and effective method to remove this part of organic matter.

[0023] Therefore, the present invention adopts the above-mentioned high-concentration suspended organic wastewater treatment device and method that can simultaneously recover carbon, nitrogen, phosphorus and hydrogen. The micro-electrolysis anaerobic dynamic membrane bioreactor system can efficiently remove most of the organic matter in the wastewater and partially convert it into methane to achieve recycling and utilization. The electrochemical struvite crystallization precipitation system can convert most of the ammonia nitrogen and orthophosphorus (i.e., phosphate phosphorus) in the wastewater into struvite and produce hydrogen to achieve recycling and utilization. The aerobic activated sludge degradation system can remove residual organic matter in the wastewater to achieve standard discharge.

[0024] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a flow chart of Example 1 of a device and method for treating high-concentration suspended organic wastewater capable of simultaneously recovering carbon, nitrogen, phosphorus and hydrogen according to the present invention;

[0026] Figure 2 This is a flow chart of comparative example 1 of a high-concentration suspended organic wastewater treatment device and method capable of simultaneously recovering carbon, nitrogen, phosphorus and hydrogen according to the present invention.

[0027] Reference numerals

[0028] 1. Anaerobic tank; 2. Biogas bag; 3. Redox potentiometer; 4. Mixed liquor circulation pump; 5. Water inlet pump; 6. Membrane tank; 7. Micromesh filter membrane; 8. Sludge pump; 9. Suction water pump; 10. Electrolytic cell; 11. Cathode; 12. Anode; 13. Hydrogen bag; 14. Metering pump; 15. Aeration tank; 16. Secondary sedimentation tank; 17. Reflux pump; 18. Controller; 19. Micro-electrolysis unit; 20. Biogas circulation aeration fan. DETAILED DESCRIPTION

[0029] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments.

[0030] Unless otherwise defined, the technical or scientific terms used in the present invention shall have the usual meanings understood by persons of ordinary skill in the field to which the present invention belongs. The words "first", "second" and similar terms used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "include" or "comprise" mean that the elements or objects preceding the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0031] The present invention provides a high-concentration suspended organic wastewater treatment device capable of simultaneously recovering carbon, nitrogen, phosphorus, and hydrogen. The device comprises a micro-electrolysis anaerobic dynamic membrane bioreactor system, an electrochemical struvite crystallization precipitation system, and an aerobic activated sludge degradation system. The micro-electrolysis anaerobic dynamic membrane bioreactor system is connected to the electrochemical struvite crystallization precipitation system, which in turn is connected to the aerobic activated sludge degradation system. The micro-electrolysis anaerobic dynamic membrane bioreactor system is used to perform efficient anaerobic treatment of wastewater to remove organic matter and recover methane. The electrochemical struvite crystallization precipitation system is used to perform electrochemical struvite crystallization precipitation on the effluent treated by the micro-electrolysis anaerobic dynamic membrane bioreactor system to remove nitrogen and phosphorus and recover struvite and hydrogen. The aerobic activated sludge degradation system is used to deeply remove residual organic matter in the effluent treated by the combined micro-electrolysis anaerobic dynamic membrane bioreactor and electrochemical struvite crystallization precipitation process, thereby achieving standard discharge.

[0032] The micro-electrolysis anaerobic dynamic membrane bioreactor system includes an anaerobic tank 1, which is used to perform anaerobically treatment on wastewater. The anaerobic tank 1 is connected to a biogas bag 2 and a water inlet pump 5. The water inlet pump 5 is used to pump wastewater into the anaerobic tank 1. The biogas produced when the organic matter in the wastewater is decomposed is collected in the biogas bag 2. The anaerobic tank 1 is also connected to a biogas circulation aeration blower 20. The biogas circulation aeration maintains a uniform mixing state in the anaerobic tank 1, thereby promoting the anaerobic digestion reaction rate. The anaerobic tank 1 is connected to a low-cost carbon electrode micro-electrolysis unit 19. By electrolyzing water, the anaerobic tank 1 is supplied with trace amounts of oxygen and hydrogen, thereby promoting the metabolic activity of hydrolytic bacteria and hydrogenophilic methanogens, respectively, thereby increasing the solubility / hydrolysis rate and methane production of suspended and macromolecular organic matter. A redox potentiometer 3 is installed in the anaerobic tank 1. The redox potentiometer 3 and the cheap carbon electrode micro-electrolysis unit 19 are connected to the controller 18. The redox potentiometer 3 monitors the redox potential in the anaerobic tank 1 in real time, and controls the cheap carbon electrode micro-electrolysis unit 19 to automatically run intermittently through the controller 18 to ensure the anaerobic treatment effect.

[0033] The anaerobic tank 1 is connected to the membrane tank 6 via a mixed liquor circulation pump 4. The membrane tank 6 is used to receive the mixed liquor treated in the anaerobic tank 1. An overflow return pipe is also provided between the anaerobic tank 1 and the membrane tank 6 to balance the liquid levels of the two tanks. A low-cost micromesh filter 7 is installed within the membrane tank 6. The low-cost micromesh filter 7 is used to filter the anaerobic sludge mixed liquor to achieve solid-liquid separation. During the filtration process, sludge flocs are deposited on the surface of the low-cost micromesh filter 7, forming a dynamic sludge layer that enhances the retention capacity, purifying the effluent quality and simultaneously achieving sludge concentration. The membrane tank 6 is connected to the electrochemical struvite crystallization precipitation system via a suction water production pump 9. The suction water production pump 9 is used to transport the wastewater in the membrane tank 6 to the electrochemical struvite crystallization precipitation system. A sludge discharge pump 8 is installed at the bottom of the membrane tank 6 to discharge the excess sludge in the membrane tank 6. The top of the membrane tank is connected to the biogas bag 2 to collect the small amount of biogas produced in the membrane tank.

[0034] The electrochemical struvite crystallization precipitation system includes a fluidized bed configuration electrolytic cell 10, which is used to receive effluent treated by a micro-electrolysis anaerobic dynamic membrane bioreactor system. The electrolytic cell 10 is connected to a hydrogen bag 13, which is used to collect hydrogen generated during the electrolysis process. A struvite precipitation recovery component is installed at the bottom of the electrolytic cell 10. The struvite precipitation recovery component adopts a structure in the prior art and is used to collect and recover precipitates generated during the electrolysis process, further improving the recycling rate of resources. The cathode 11 and the anode 12 of the electrolytic cell 10 are respectively connected to the negative and positive poles of the power supply. The electrolytic cell 10 is connected to a metering pump 14, and a supernatant overflow outlet pipe is provided above it. The metering pump 14 is used to accurately control the amount of ammonium salt or phosphate added to match the molar ratio of ammonia nitrogen and phosphate phosphorus in the water to 1. The outlet water of the suction water production pump 9 and the metering pump 14 flows upward from the bottom of the electrode through the electrode plate area, and the magnesium anode 12 and the stainless steel cathode 11 are used to electrolyze the outlet water of the micro-electrolysis anaerobic dynamic membrane bioreactor system to provide magnesium ions and hydroxide ions to generate struvite crystals. The advantages include that the struvite is preferentially deposited near the cathode 11, thereby being easy to separate and dehydrate; there is no interference from suspended matter in the water, thereby generating high-purity struvite; some difficult-to-degrade organic matter can be oxidized, thereby reducing subsequent processing costs; renewable electricity such as wind power and photovoltaic power can be used, thereby reducing costs; and hydrogen, a high-value by-product, can be generated, thereby further increasing profits and reducing costs.

[0035] The aerobic activated sludge degradation system includes an aeration tank 15, which is used to receive effluent treated by electrochemical struvite crystallization precipitation. Sufficient dissolved oxygen is provided to the tank through air aeration, so that aerobic microorganisms can remove residual organic matter in the wastewater and further purify the water quality. The aeration tank 15 is connected to the secondary sedimentation tank 16, which is used to receive the mixed liquor treated by the aeration tank 15. The secondary sedimentation tank 16 is connected to a return pump 17, the other end of which is connected to the aeration tank 15. The return pump 17 returns the precipitated activated sludge to the aeration tank 15, replenishes the amount of microorganisms in the aeration tank 15, and maintains the stable operation of the aerobic treatment system. The wastewater treated by aeration in the secondary sedimentation tank 16 is subjected to mud-water separation to allow the activated sludge to settle, and the supernatant is used as the treated effluent to meet the discharge standards or be further reused.

[0036] The present invention also provides a method for treating high-concentration suspended organic wastewater capable of simultaneously recovering carbon, nitrogen, phosphorus and hydrogen, which uses the above-mentioned high-concentration suspended organic wastewater treatment device capable of simultaneously recovering carbon, nitrogen, phosphorus and hydrogen, comprising the following steps:

[0037] Step 1: First, the high-concentration suspended organic wastewater is transported to the anaerobic tank 1 through the water inlet pump 5 for anaerobic digestion treatment. At the same time, the anaerobic tank is kept in a uniform mixed state through aeration by the biogas circulation fan 20, and the cheap carbon electrode micro-electrolysis unit 19 is controlled by the redox potentiometer 3 to supply trace oxygen and hydrogen to the anaerobic tank 1. The treated anaerobic sludge mixed liquor is then transported to the membrane tank 6 through the mixed liquor circulation pump 4, and the cheap micro-mesh filter membrane 7 with a dynamic sludge layer attached to the surface is used for mud and water separation. The remaining sludge is discharged through the sludge pump 8, and the biogas is collected and utilized through the biogas bag 2.

[0038] The micro-electrolysis unit uses cheap carbon brush electrodes with an electrode spacing of 1-3 cm and an electrode voltage of 1.2-2 V. The hydraulic retention time in the anaerobic tank is 1-5 days, the sludge retention time is 30-100 days, and the temperature is room temperature. The flux of the cheap micro-mesh filter is 5-15 L / m 2 / d; The micro-electrolysis unit automatically operates intermittently based on the fluctuation of the redox potential in the anaerobic tank between -400mV and -150mV.

[0039] Step 2: The water effluent from the micromesh filter 7 in step 1 is sucked into the electrolytic cell 10 through the suction water pump 9, and an appropriate amount of ammonium salt or phosphate is added to the electrolytic cell 10 through the metering pump 14 to match the molar ratio of ammonia nitrogen and phosphate phosphorus in the water to 1. The water effluent from the suction water pump 9 and the metering pump 14 flows upward from the bottom of the electrode through the electrode plate area, and struvite crystals are generated near the anode 12 and precipitated to the bottom and collected and utilized by the recovery system. The difficult-to-degrade organic matter is oxidized near the cathode 11 and hydrogen is generated and collected and utilized by the hydrogen bag 13.

[0040] The cathode 11 of the electrolytic cell 10 is a nickel-plated stainless steel plate or a platinum-plated carbon plate, the anode 12 is a magnesium plate, the hydraulic retention time in the electrolytic cell 10 is 1-5 hours, the electrode voltage is 1.5-3V, and the electrode spacing is 0.5-1.5cm.

[0041] Step 3: The supernatant in step 2 is flowed into the aeration tank 15 through the supernatant overflow outlet pipe. Aerobic microorganisms use the oxygen provided by air aeration to decompose part of the residual organic matter in the wastewater into carbon dioxide and water, and part of it is used for microbial proliferation. The resulting mixed liquid is then passed into the secondary sedimentation tank 16 for solid-liquid separation. The precipitated sludge is partially returned to the aeration tank 15 to maintain the microbial concentration, and the remaining sludge is discharged from the system.

[0042] The hydraulic retention time in the aeration tank 15 is 6-24 hours, the sludge retention time is 10-20 days, and the dissolved oxygen is not less than 2 mg / L.

[0043] Example 1

[0044] like Figure 1 As shown, the high-concentration suspended organic wastewater treated in this embodiment was taken from an intensive pig farm in the suburbs of Guangzhou. The wastewater quality was as follows: total suspended solids 23.5 g / L, volatile suspended solids 20.8 g / L, total COD 24.6 g / L, soluble COD 5.5 g / L, ammonia nitrogen 402 mg / L, total nitrogen 448 mg / L, orthophosphorus 114 mg / L, and total phosphorus 133 mg / L.

[0045] The micro-electrolysis anaerobic dynamic membrane bioreactor system was used to treat the above pig farm wastewater. The system was used under the conditions of hydraulic retention time of 3 days, sludge retention time of 50 days, room temperature, and membrane flux of 12 L / m 2 / d, micro-electrolysis unit (carbon brush electrode spacing 1cm, voltage 1.5V), with the redox potential in anaerobic tank 1 fluctuating between -400mV and -150mV as the standard, automatic intermittent oxygen and hydrogen supply and other operating conditions, the average effluent COD 1250mg / L (average removal rate up to 94.9%), average ammonia nitrogen 435mg / L and average orthophosphorus 128mg / L (some organic nitrogen and phosphorus are converted into ammonia nitrogen and orthophosphorus under anaerobic conditions, so the effluent is higher than the inlet), average total nitrogen 440mg / L, average total phosphorus 130mg / L, no suspended solids, and average biogas production 10.7m 3 / m 3 Treated water, average methane content 70%, methane recovery 0.32m 3 / kg COD.

[0046] The electrochemical struvite crystallization precipitation system is used to treat the effluent of the micro-electrolysis anaerobic dynamic membrane bioreactor system. Under the operating conditions that the anode 12 is a magnesium plate, the cathode 11 is preferably a nickel-plated stainless steel plate, the hydraulic retention time is 5 hours, the electrode voltage is 1.5V, the electrode spacing is 1cm, and 835mg / L of orthophosphorus is added (to meet the molar ratio of ammonia nitrogen and orthophosphorus required for struvite precipitation), the effluent has an average ammonia nitrogen of 5mg / L, an average total nitrogen of 8mg / L, an average orthophosphorus of 4mg / L, an average total phosphorus of 5mg / L, and an average COD of 1120mg / L. The purity of the recovered struvite is as high as 96.3%, and the struvite recovery amount is 7.5kg / m 3 Treat water, hydrogen recovery volume 0.1m 3 / m 3 Treat water.

[0047] An aerobic activated sludge degradation system was used to treat the effluent from the electrochemical struvite crystallization precipitation system. Under the conditions of a hydraulic retention time of 5 hours, a sludge retention time of 15 days, and dissolved oxygen of not less than 2 mg / L, the average effluent COD was 310 mg / L, the average ammonia nitrogen was 2 mg / L, the average total nitrogen was 5 mg / L, the average orthophosphorus was 1 mg / L, and the average total phosphorus was 2 mg / L, which were significantly better than the corresponding requirements of the National Pollutant Emission Standard for Livestock and Poultry Farming (GB 18596-2001) and various local relevant emission standards.

[0048] According to the process parameters and operation results of this embodiment, the pig farm wastewater (1000m 3 / d) Conduct engineering design and cost-benefit analysis of the combined technology of micro-electrolysis anaerobic dynamic membrane bioreactor-electrochemical struvite crystallization precipitation-aerobic activated sludge degradation. The volumes of micro-electrolysis anaerobic dynamic membrane bioreactor, electrochemical struvite crystallization precipitation reactor, and aerobic activated sludge reactor are 3000m 3 、208m 3 、208m 3 , using reinforced concrete structure at a cost of 1000 yuan / m 3 , based on the depreciation calculation of 50-year service life, the total investment cost of the reactor is RMB 3.417 million, and the depreciation operating cost is RMB 0.2 / m 3 The non-woven filter membrane area is 3500m 2 , based on a cost of 30 yuan / m 2 , based on a 3-year service life depreciation calculation, the investment cost of the non-woven filter membrane is 105,000 yuan, and the depreciation operating cost is 0.1 yuan / m 3 The total investment cost of the water pump, fan, micro-electrolysis unit and pipe fittings is RMB 300,000. The operating cost is RMB 0.1 / m2 based on a 10-year depreciation service life. 3 The power consumption of micro-electrolysis anaerobic dynamic membrane bioreactor, electrochemical struvite crystallization precipitation, and aerobic activated sludge degradation is 0.4kWh / m3 , 2.2kWh / m 3 , 0.5kWh / m 3 The electricity price is calculated at 0.7 yuan / kWh, and the total electricity consumption cost is 2.2 yuan / m 3 The magnesium anode consumption is 0.75kg / m 3 Calculated at a cost of 20 yuan / kg, the operating cost of magnesium anode is 15 yuan / m 3 The amount of added phosphorus is 0.84kg / m 3 Calculated at a cost of 49 yuan / kg, plus the operating cost of orthophosphorus is 41 yuan / m 3 . Labor and other operating costs total 0.45 yuan / m 3 Based on the above cost calculation, the total investment cost of the project is RMB 3.82 million, equivalent to RMB 3,820 / m 3 / d, the total operating cost of the project is 59 yuan / m 3 . Methane production is 7.5m 3 / m 3 , according to the market price of 0.7 yuan / m 3 Calculation shows that the methane benefit is 5.2 yuan / m 3 The struvite production is 7.5kg / m 3 Calculated at the market price of 7.7 yuan / kg, the profit of struvite is 58 yuan / m 3 . Hydrogen production is 0.1m 3 / m 3 , according to the market price of 3 yuan / m 3 Calculation shows that the hydrogen revenue is 0.3 yuan / m 3 Based on the above calculation, the total project income is 63.5 yuan / m 3 After deducting the total operating costs, the net profit is 4.5 yuan / m 3 The investment cost recovery period is 2.3 years, indicating that the micro-electrolysis anaerobic dynamic membrane bioreactor-electrochemical struvite crystallization precipitation-aerobic activated sludge degradation combined technology solution has good technical and economic performance.

[0049] Comparative Example 1

[0050] like Figure 2 As shown, in Comparative Example 1, a completely mixed anaerobic digestion reactor + centrifugal dehydration system was used to treat the above-mentioned pig farm wastewater. Under the operating conditions of a hydraulic retention time and a sludge retention time of 20 days, room temperature, and a centrifugal force of 1000g for 30 minutes, the average COD of the effluent was 5150 mg / L (average removal rate of 79.1%), an average ammonia nitrogen of 418 mg / L, and an average orthophosphorus of 120 mg / L (part of the organic nitrogen and phosphorus were converted into ammonia nitrogen and orthophosphorus under anaerobic conditions, so the effluent was higher than the influent), an average total nitrogen of 442 mg / L, an average total phosphorus of 131 mg / L, and suspended solids of 3480 mg / L, and an average biogas production of 7.9 m3 / m 3 Treated water, average methane content 60%, methane recovery 0.24m 3 / kg COD.

[0051] The effluent from the above-mentioned completely mixed anaerobic digestion reactor + centrifugal dehydration system was treated by a chemical struvite crystallization precipitation system. Under the operating conditions of adding 2842 mg / L of magnesium chloride hexahydrate and 806 mg / L of orthophosphorus (to meet the molar ratio of ammonia nitrogen and orthophosphorus required for struvite precipitation) and a hydraulic retention time of 5 h, the effluent had an average ammonia nitrogen of 4 mg / L, an average total nitrogen of 9 mg / L, an average orthophosphorus of 6 mg / L, an average total phosphorus of 8 mg / L, an average COD of 4980 mg / L, and an average effluent suspended solids of 3140 mg / L. The recovered struvite had a purity of 80.3% and a struvite recovery of 7.4 kg / m 3 Treat water.

[0052] An aerobic activated sludge degradation system was used to treat the effluent from the chemical struvite crystallization precipitation system. Under the conditions of a hydraulic retention time of 16 hours, a sludge retention time of 8 days, and dissolved oxygen of not less than 2 mg / L, the average effluent COD was 367 mg / L, the average ammonia nitrogen was 2 mg / L, the average total nitrogen was 6 mg / L, the average orthophosphorus was 2 mg / L, and the average total phosphorus was 5 mg / L, which exceeded the corresponding requirements of the National Pollutant Emission Standard for Livestock and Poultry Breeding (GB 18596-2001).

[0053] According to the process parameters and operation results of comparative example 1, the pig farm wastewater (1000m 3 / d) to conduct engineering design and cost-benefit analysis of the combined technology of complete mixed anaerobic digestion + centrifugal dehydration - chemical struvite crystallization precipitation - aerobic activated sludge degradation. The volumes of the complete mixed anaerobic digestion reactor, chemical struvite crystallization precipitation reactor, and aerobic activated sludge reactor are 20,000 m 3 、209m 3 、669m 3 , using reinforced concrete structure at a cost of 1000 yuan / m 3 , based on a 50-year service life, the total investment cost of the reactor is RMB 20.878 million, and the depreciation operating cost is RMB 1.14 / m 3 The total investment cost of water pumps, fans, centrifuges and pipe fittings is RMB 406,000. The operating cost is RMB 0.11 / m2 based on a 10-year depreciation life. 3 The power consumption of fully mixed anaerobic digestion + centrifugal dehydration, chemical struvite crystallization precipitation, and aerobic activated sludge degradation is 0.2kWh / m 3 , 0.1kWh / m 3 , 2kWh / m 3The electricity price is calculated at 0.7 yuan / kWh, and the total electricity consumption cost is 1.6 yuan / m 3 The magnesium chloride consumption is 2.84kg / m 3 Calculated at a cost of 5.6 yuan / kg, the operating cost of magnesium chloride is 15.8 yuan / m 3 The amount of added phosphorus is 0.81kg / m 3 Calculated at a cost of 49 yuan / kg, plus orthophosphorus, the operating cost is 39.3 yuan / m 3 . Labor and other operating costs total 0.45 yuan / m 3 Based on the above cost calculation, the total investment cost of the project is 21.28 million yuan, equivalent to 21,280 yuan / m 3 / d, the total operating cost of the project is 58.4 yuan / m 3 . Methane production is 4.7m 3 / m 3 , according to the market price of 0.7 yuan / m 3 Calculation shows that the methane benefit is 3.3 yuan / m 3 The struvite production is 7.2kg / m 3 Calculated at the market price of 7.7 yuan / kg, the profit of struvite is 55.8 yuan / m 3 Based on the above calculation, the total project income is 59.1 yuan / m 3 After deducting the total operating costs, the net profit is 0.7 yuan / m 3 The investment cost recovery period is 89.3 years.

[0054] It can be seen from the above data that the economic efficiency of the micro-electrolysis anaerobic dynamic membrane bioreactor-electrochemical struvite crystallization precipitation-aerobic activated sludge degradation combined technical solution of Example 1 is significantly higher than that of the traditional completely mixed anaerobic digestion + centrifugal dehydration-chemical struvite crystallization precipitation-aerobic activated sludge degradation combined technical solution in Comparative Example 1.

[0055] Therefore, the present invention adopts the above-mentioned high-concentration suspended organic wastewater treatment device and method that can simultaneously recover carbon, nitrogen, phosphorus and hydrogen. The micro-electrolysis anaerobic dynamic membrane bioreactor system can efficiently remove most of the organic matter in the wastewater and partially convert it into methane to achieve recycling and utilization. The electrochemical struvite crystallization precipitation system can convert most of the ammonia nitrogen and orthophosphorus (i.e., phosphate phosphorus) in the wastewater into struvite and produce hydrogen to achieve recycling and utilization. The aerobic activated sludge degradation system can remove residual organic matter in the wastewater to achieve standard discharge, ultimately achieving a win-win situation of water ecology and economic benefits.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A device for treating high-concentration suspended organic wastewater capable of simultaneously recovering carbon, nitrogen, phosphorus and hydrogen, characterized by: It includes a micro-electrolysis anaerobic dynamic membrane bioreactor system, an electrochemical struvite crystallization precipitation system and an aerobic activated sludge degradation system. The micro-electrolysis anaerobic dynamic membrane bioreactor system is connected to the electrochemical struvite crystallization precipitation system, and the electrochemical struvite crystallization precipitation system is connected to the aerobic activated sludge degradation system.

2. The high-concentration suspended organic wastewater treatment device capable of simultaneously recovering carbon, nitrogen, phosphorus and hydrogen according to claim 1, characterized in that: The micro-electrolysis anaerobic dynamic membrane bioreactor system includes an anaerobic tank, which is connected to the membrane tank through a mixed liquid circulation pump. An overflow return pipe is also provided between the anaerobic tank and the membrane tank. The membrane tank is connected to the electrochemical struvite crystallization precipitation system through a suction water pump.

3. The high-concentration suspended organic wastewater treatment device capable of simultaneously recovering carbon, nitrogen, phosphorus and hydrogen according to claim 2, characterized in that: The anaerobic tank is connected to the biogas bag and the water inlet pump. The anaerobic tank is also connected to the biogas circulation aeration fan and the cheap carbon electrode micro-electrolysis unit. A redox potentiometer is installed in the anaerobic tank. The redox potentiometer and the cheap carbon electrode micro-electrolysis unit are both connected to the controller.

4. The high-concentration suspended organic wastewater treatment device capable of simultaneously recovering carbon, nitrogen, phosphorus and hydrogen according to claim 3, characterized in that: The membrane pool is equipped with a cheap micro-mesh filter membrane with a dynamic sludge layer attached to the surface. A sludge pump is installed at the bottom of the membrane pool, and the top of the membrane pool is connected to the biogas bag.

5. The high-concentration suspended organic wastewater treatment device capable of simultaneously recovering carbon, nitrogen, phosphorus and hydrogen according to claim 1, characterized in that: The electrochemical struvite crystallization precipitation system includes a fluidized bed configuration electrolytic cell, the electrolytic cell is connected to a hydrogen bag, a struvite precipitation recovery component is installed at the bottom of the electrolytic cell, the electrolytic cell is connected to a suction water pump and a metering pump, and a supernatant overflow outlet pipe is provided above the electrolytic cell.

6. The device for treating high-concentration suspended organic wastewater capable of simultaneously recovering carbon, nitrogen, phosphorus and hydrogen according to claim 1, characterized in that: The aerobic activated sludge degradation system includes an aeration tank, the aeration tank is connected to a secondary sedimentation tank, the secondary sedimentation tank is connected to a return pump, and the other end of the return pump is connected to the aeration tank.

7. A method for treating high-concentration suspended organic wastewater capable of simultaneously recovering carbon, nitrogen, phosphorus, and hydrogen, using the high-concentration suspended organic wastewater treatment device capable of simultaneously recovering carbon, nitrogen, phosphorus, and hydrogen according to any one of claims 1 to 6, characterized in that: The following steps are involved: Step 1: First, high-concentration suspended organic wastewater is transported to the anaerobic tank through the water inlet pump for anaerobic digestion treatment. At the same time, the anaerobic tank is kept uniformly mixed through aeration by the biogas circulation fan, and the inexpensive carbon electrode micro-electrolysis unit is controlled by the redox potentiometer to supply trace oxygen and hydrogen to the anaerobic tank. The treated anaerobic sludge mixture is then transported to the membrane tank through the mixed liquid circulation pump, and the inexpensive micro-mesh filter membrane with a dynamic sludge layer attached to the surface is used for mud and water separation. The remaining sludge is discharged through the sludge discharge pump, and the biogas is collected and utilized by the biogas bag; Step 2: The effluent from the cheap micromesh filter in step 1 is sucked into the electrolytic cell through a suction water pump, and an appropriate amount of ammonium salt or phosphate is added to the electrolytic cell through a metering pump to match the molar ratio of ammonia nitrogen and phosphate phosphorus in the water to 1. The effluent from the suction water pump and the metering pump flows upward from the bottom of the electrode through the electrode plate area, and struvite crystals are generated near the anode and then precipitated to the bottom and collected and utilized by a recovery system. The refractory organic matter is oxidized near the cathode to generate hydrogen, which is collected and utilized by a hydrogen bag; Step 3: The supernatant in step 2 is flowed into the aeration tank through the supernatant overflow outlet pipe. Aerobic activated sludge microorganisms use the oxygen provided by air aeration to decompose part of the residual organic matter in the wastewater into carbon dioxide and water, and part of it is used for microbial proliferation. The resulting mixed liquid is then passed into the secondary sedimentation tank for solid-liquid separation. The precipitated sludge is partially returned to the aeration tank to maintain the microbial concentration, and the remaining sludge is discharged from the system.

8. The method for treating high-concentration suspended organic wastewater capable of simultaneously recovering carbon, nitrogen, phosphorus and hydrogen according to claim 7, characterized in that: In step 1, the micro-electrolysis unit uses cheap carbon brush electrodes with an electrode spacing of 1-3 cm and an electrode voltage of 1.2-2 V. The hydraulic retention time in the anaerobic tank is 1-5 days, the sludge retention time is 30-100 days, and the temperature is room temperature. The flux of the cheap micro-mesh filter is 5-15 L / m 2 / d; The micro-electrolysis unit automatically operates intermittently based on the fluctuation of the redox potential in the anaerobic tank between -400mV and -150mV.

9. The method for treating high-concentration suspended organic wastewater capable of simultaneously recovering carbon, nitrogen, phosphorus and hydrogen according to claim 7, characterized in that: In step 2, the cathode of the electrolytic cell is a nickel-plated stainless steel plate or a platinum-plated carbon plate, the anode is a magnesium plate, the hydraulic retention time of the electrolytic cell is 1-5h, the electrode voltage is 1.5-3V, and the electrode spacing is 0.5-1.5cm.

10. The method for treating high-concentration suspended organic wastewater capable of simultaneously recovering carbon, nitrogen, phosphorus and hydrogen according to claim 7, characterized in that: In step 3, the hydraulic retention time of the aeration tank is 6-24 hours, the sludge retention time is 10-20 days, and the dissolved oxygen is not less than 2 mg / L.

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