A device and method for treating high-concentration suspended organic wastewater capable of synchronously recovering carbon, nitrogen, phosphorus and hydrogen

Abstract

This invention discloses a device and method for treating high-concentration suspended organic wastewater capable of simultaneously recovering carbon, nitrogen, phosphorus, and hydrogen. Belonging to the technical field of high-concentration suspended organic wastewater treatment, it includes 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 to the electrochemical struvite crystallization and precipitation system, which is also connected to the aerobic activated sludge degradation system. This invention employs the aforementioned device and method for treating high-concentration suspended organic wastewater capable of simultaneously recovering carbon, nitrogen, phosphorus, and hydrogen. The micro-electrolysis anaerobic dynamic membrane bioreactor system efficiently removes most of the organic matter and partially converts it into methane for recycling. The electrochemical struvite crystallization and precipitation system converts most of the ammonia nitrogen and orthophosphorus into struvite and generates hydrogen for recycling. The aerobic activated sludge degradation system removes residual organic matter to achieve compliant discharge.

Description

Technical Field

[0001] This invention relates to the field of high-concentration suspended organic wastewater treatment technology, and in particular to a device and method for treating high-concentration suspended organic wastewater that can simultaneously recover carbon, nitrogen, phosphorus and hydrogen. Background Technology

[0002] Livestock farming, biopharmaceutical manufacturing, and waste treatment industries generate large quantities of highly concentrated wastewater rich in suspended organic matter and nitrogen and phosphorus nutrients. The high concentrations of organic matter and nitrogen and phosphorus in this wastewater are carriers of resources and energy, necessitating efficient treatment methods to reduce pollutant emissions while simultaneously recovering resources and energy.

[0003] High-concentration suspended organic wastewater is typically treated anaerobicly to convert organic matter into carbon dioxide and methane for power generation, thus 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 solids (volatile suspended solids up to 20 g / L, COD up to 80%), and the slow dissolution / hydrolysis rate based on the extracellular surface reaction mechanism of microorganisms becomes the main bottleneck restricting its anaerobic digestion efficiency. High concentrations of suspended solids lead to long hydraulic retention times, large footprints, and low COD removal and methane conversion efficiency in traditional completely mixed anaerobic digestion processes. Furthermore, they affect the formation of granular sludge, requiring intensive pretreatment to significantly reduce its concentration before direct application to high-load anaerobic digestion processes, such as upflow anaerobic sludge blanket systems, thereby significantly increasing treatment costs.

[0004] After anaerobic digestion and solid-liquid separation, most of the suspended solids and organic matter in high-concentration suspended organic wastewater are removed. The remaining ammonium ions (containing ammonia nitrogen) and phosphate ions (containing phosphorus) in the effluent, along with added magnesium ions, will crystallize into struvite (magnesium ammonium phosphate) under appropriate conditions, thus precipitating out (Mg). 2+ +NH4 + +H n PO4 3-n +6H₂O→MgNH₄PO₄·6H₂O↓+nH + Furthermore, it can be recycled. Struvite is a high-quality slow-release nitrogen and phosphorus compound fertilizer, 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 from anaerobic digestion + solid-liquid separation process is a common method, but the resulting struvite crystals are fine and difficult to separate and dehydrate, and the cost of adding the chemicals is also relatively high.

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

[0006] The purpose of this invention is to provide a device and method for treating high-concentration suspended organic wastewater 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., phosphorus phosphate) in the wastewater into struvite and generate hydrogen for recycling. The aerobic activated sludge degradation system can remove residual organic matter in the wastewater to achieve compliant discharge.

[0007] To achieve the above objectives, the present invention provides a high-concentration suspended organic wastewater treatment device capable of simultaneously recovering carbon, nitrogen, phosphorus, and hydrogen, comprising 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 to the electrochemical struvite crystallization and precipitation system, and the electrochemical struvite crystallization and 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 via a mixed liquor circulation pump. An overflow return water pipe is also provided between the anaerobic tank and the membrane tank. The membrane tank is connected to an electrochemical struvite crystallization and precipitation system via a permeate pump.

[0009] Preferably, the anaerobic digester is connected to a biogas bag and an inlet pump. The anaerobic digester is also connected to a biogas circulation aerator and a low-cost carbon electrode micro-electrolysis unit. An oxidation-reduction potentiometer is installed in the anaerobic digester, and both the oxidation-reduction potentiometer and the low-cost carbon electrode micro-electrolysis unit are connected to a controller.

[0010] Preferably, the membrane tank is equipped with an inexpensive micro-mesh filter membrane with a dynamic sludge layer attached to its surface, a sludge discharge pump is installed at the bottom of the membrane tank, and the top of the membrane tank is connected to a biogas bag.

[0011] Preferably, the electrochemical struvite crystallization and precipitation system includes a fluidized bed electrolytic cell, which is connected to a hydrogen bag. A struvite precipitation and recovery component is installed at the bottom of the electrolytic cell. The electrolytic cell is connected to a pump for pumping water 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 connected to a secondary sedimentation tank, the secondary sedimentation tank being connected to a return pump, and the other end of the return pump being connected to the aeration tank.

[0013] This invention also provides a method for treating high-concentration suspended organic wastewater that can simultaneously recover carbon, nitrogen, phosphorus, and hydrogen, using the aforementioned device for treating high-concentration suspended organic wastewater that can simultaneously recover carbon, nitrogen, phosphorus, and hydrogen, comprising the following steps:

[0014] Step 1: First, high-concentration suspended organic wastewater is pumped to the anaerobic tank for anaerobic digestion. At the same time, a biogas circulating blower is used to maintain a uniform mixing state in the anaerobic tank, and a low-cost carbon electrode micro-electrolysis unit is controlled by an oxidation-reduction potentiometer to supply a small amount of oxygen and hydrogen to the anaerobic tank. Then, the treated anaerobic sludge mixture is pumped to the membrane tank through a mixed liquor circulation pump. A low-cost micro-mesh filter membrane with a dynamic sludge layer on its surface is used for sludge-water separation. The remaining sludge is discharged through a sludge discharge pump, and the biogas is collected and utilized through a biogas bag.

[0015] Step 2: The effluent from the inexpensive micro-mesh filter membrane in Step 1 is pumped into the electrolytic cell using a pumping permeate pump. An appropriate amount of ammonium salt or phosphate is added to the electrolytic cell using a metering pump to match the ammonia nitrogen and phosphate phosphorus molar ratio in the water to 1. The effluent from both the pumping permeate pump and the metering pump flows upward from below the electrodes through the electrode plate area. Struvite crystals are formed near the anode and then precipitate to the bottom and are collected and utilized through a recycling system. Near the cathode, recalcitrant organic matter is oxidized to produce hydrogen gas, which is collected and utilized through a hydrogen gas bag.

[0016] Step 3: The supernatant from Step 2 is discharged into the aeration tank through the supernatant overflow pipe. The 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 mixture is then fed into the secondary sedimentation tank for solid-liquid separation. Part of the precipitated sludge is returned to the aeration tank to maintain the microbial concentration, and the remaining sludge is discharged from the system.

[0017] Preferably, in step one, the micro-electrolysis unit uses inexpensive 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 inexpensive micromembrane filter is 5-15 L / m³. 2 / d; The micro-electrolysis unit operates automatically and intermittently based on the fluctuation of the oxidation-reduction potential in the anaerobic tank between -400mV and -150mV.

[0018] Preferably, in step two, 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 residence time of the electrolytic cell is 1-5 hours, the electrode voltage is 1.5-3V, and the electrode spacing is 0.5-1.5cm.

[0019] Preferably, in step three, 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] The use of inexpensive micromembrane filter membranes, such as those made of non-woven fabric, to replace the gravity sedimentation coupling in traditional anaerobic digestion processes in anaerobic dynamic membrane bioreactors has potential technological advantages in the treatment of high-concentration suspended organic wastewater. The inexpensive micromembrane filter membrane with a dynamic sludge layer attached to its surface has filtration precision similar to micro / ultrafiltration membranes, completely retaining anaerobic sludge flocs, efficiently retaining suspended organic matter, and partially retaining macromolecular organic matter. On the one hand, it achieves complete separation of hydraulic retention time and sludge retention time, allowing the anaerobic tank to operate in a highly efficient state with short hydraulic retention time and long sludge retention time (high COD removal and methane conversion rate, low effluent COD, and low excess sludge production); on the other hand, it extends the retention time of suspended and macromolecular organic matter (i.e., the biochemical reaction time with anaerobic microorganisms), achieving partial separation from the hydraulic retention time, thereby enhancing their degradation and methane production effects. Simultaneously, the cost of the inexpensive micromembrane filter membrane is far lower than that of the micro / ultrafiltration membranes used in traditional anaerobic membrane bioreactors, offering a significant cost advantage. Providing trace amounts of oxygen and hydrogen to an anaerobic dynamic membrane bioreactor system via micro-electrolysis using inexpensive carbon electrodes offers the following advantages: 1) Trace oxygen enhances the metabolic activity of hydrolytic bacteria, thereby increasing the dissolution / hydrolysis rate of suspended and macromolecular organic matter and promoting methanogenesis efficiency; 2) Trace oxygen removes hydrogen sulfide from biogas, reducing the cost of subsequent biogas utilization; 3) Trace oxygen promotes the aggregation of anaerobic sludge flocs, improving the filtration performance of anaerobic sludge mixed liquor; 4) Trace hydrogen promotes the reduction of carbon dioxide to methane, increasing the methane content in biogas; 5) Inexpensive carbon electrodes offer a significant cost advantage compared to traditional metal electrodes used in water electrolysis. Therefore, the micro-electrolysis anaerobic dynamic membrane bioreactor process can significantly improve organic matter removal, methane recovery, and membrane filtration efficiency when treating high-concentration suspended organic wastewater.

[0021] The micro-electrolysis anaerobic dynamic membrane bioreactor system, which utilizes magnesium anodes and inert cathodes to electrolyze effluent, provides magnesium and hydroxide ions to generate struvite. This system offers numerous advantages, including struvite preferentially depositing near the anode for easy separation and dehydration, high-purity struvite generated due to the absence of suspended solids in the water, the ability to oxidize some recalcitrant organic matter to reduce subsequent treatment costs, the utilization of renewable energy sources such as wind and solar power for low cost, and the generation of hydrogen as a high-value byproduct to further increase profitability and reduce costs.

[0022] After high-concentration suspended organic wastewater is treated by a combination of a micro-electrolysis anaerobic dynamic membrane bioreactor system and an electrochemical struvite crystallization sedimentation system, only a small amount of organic matter in the effluent needs to be removed to meet discharge standards. Aerobic activated sludge degradation is the most economical and effective method for removing this portion of organic matter.

[0023] Therefore, the present invention employs the above-mentioned device and method for treating high-concentration suspended organic wastewater 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., phosphorus phosphate) in the wastewater into struvite and generate hydrogen for recycling. The aerobic activated sludge degradation system can remove residual organic matter in the wastewater to achieve compliant discharge.

[0024] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0025] Figure 1 This is a flowchart of Embodiment 1 of the present invention, which describes a device and method for treating high-concentration suspended organic wastewater capable of simultaneously recovering carbon, nitrogen, phosphorus, and hydrogen.

[0026] Figure 2 This is a flowchart of Comparative Example 1 of a device and method for treating high-concentration suspended organic wastewater that can simultaneously recover carbon, nitrogen, phosphorus, and hydrogen according to the present invention.

[0027] Figure Labels

[0028] 1. Anaerobic digester; 2. Biogas bag; 3. Oxidation-reduction potentiometer; 4. Mixed liquor circulation pump; 5. Inlet pump; 6. Membrane tank; 7. Micromembrane filter; 8. Sludge pump; 9. Permeate pump; 10. Electrolytic cell; 11. Cathode; 12. Anode; 13. Hydrogen bag; 14. Metering pump; 15. Aeration tank; 16. Secondary sedimentation tank; 17. Return pump; 18. Controller; 19. Micro-electrolysis unit; 20. Biogas circulation aeration blower. Detailed Implementation

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

[0030] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0031] This invention provides a high-concentration suspended organic wastewater treatment device capable of simultaneously recovering carbon, nitrogen, phosphorus, and hydrogen. It includes 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 to the electrochemical struvite crystallization and precipitation system, which is also connected to the aerobic activated sludge degradation system. The micro-electrolysis anaerobic dynamic membrane bioreactor system is used for efficient anaerobic treatment of wastewater to remove organic matter and recover methane. The electrochemical struvite crystallization and precipitation system is used to electrochemically crystallize and precipitate nitrogen and phosphorus from the effluent treated by the micro-electrolysis anaerobic dynamic membrane bioreactor system to recover struvite and hydrogen. The aerobic activated sludge degradation system is used to deeply remove residual organic matter from the effluent treated by the combined micro-electrolysis anaerobic dynamic membrane bioreactor system and the electrochemical struvite crystallization and precipitation system to achieve compliant discharge.

[0032] The micro-electrolysis anaerobic dynamic membrane bioreactor system includes an anaerobic tank 1, which is used for anaerobic treatment of wastewater. The anaerobic tank 1 is connected to a biogas bag 2 and an influent pump 5. The influent pump 5 pumps wastewater into the anaerobic tank 1, and the biogas produced during the decomposition of organic matter in the wastewater is collected in the biogas bag 2. The anaerobic tank 1 is also connected to a biogas circulation aerator 20, which maintains a uniform mixing state in the anaerobic tank 1 through biogas circulation aeration, thereby promoting the anaerobic digestion reaction rate. The anaerobic tank 1 is connected to a low-cost carbon electrode micro-electrolysis unit 19, which supplies trace amounts of oxygen and hydrogen to the anaerobic tank 1 through water electrolysis, thereby promoting the metabolic activity of hydrolytic bacteria and hydrogen-producing methanogens, respectively, and thus improving the dissolution / hydrolysis rate and methanogenesis effect of suspended and macromolecular organic matter. An oxidation-reduction potentiometer 3 is installed in the anaerobic tank 1. The oxidation-reduction potentiometer 3 and the low-cost carbon electrode micro-electrolysis unit 19 are connected to the controller 18. The oxidation-reduction potentiometer 3 monitors the oxidation-reduction potential in the anaerobic tank 1 in real time, and controls the low-cost carbon electrode micro-electrolysis unit 19 to operate automatically and intermittently through the controller 18, thereby ensuring the anaerobic treatment effect.

[0033] Anaerobic tank 1 is connected to membrane tank 6 via mixed liquor circulation pump 4. Membrane tank 6 receives the mixed liquor treated by anaerobic tank 1. An overflow return pipe is also provided between anaerobic tank 1 and membrane tank 6 to balance the liquid levels in both tanks. Membrane tank 6 contains a low-cost micro-mesh filter membrane 7, which filters the anaerobic sludge mixed liquor to achieve solid-liquid separation. During filtration, sludge flocs deposit on the surface of the low-cost micro-mesh filter membrane 7, forming a dynamic sludge layer that enhances retention capacity, purifies the effluent, and concentrates the sludge. Membrane tank 6 is connected to an electrochemical struvite crystallization and sedimentation system via a permeate pump 9, which transports wastewater from membrane tank 6 to the electrochemical struvite crystallization and sedimentation system. A sludge discharge pump 8 is installed at the bottom of membrane tank 6 to discharge excess sludge. The top of the membrane tank is connected to a biogas bag 2 to collect the small amount of biogas produced within the membrane tank.

[0034] The electrochemical struvite crystallization and precipitation system includes a fluidized bed electrolytic cell 10, which receives effluent treated by a micro-electrolysis anaerobic dynamic membrane bioreactor system. The electrolytic cell 10 is connected to a hydrogen bag 13, which collects hydrogen generated during electrolysis. A struvite precipitation and recovery assembly is installed at the bottom of the electrolytic cell 10. This assembly, employing a structure found in existing technology, collects and recovers precipitates generated during electrolysis, further improving resource recovery efficiency. The cathode 11 and anode 12 of the electrolytic cell 10 are connected to the negative and positive terminals of a power source, respectively. The electrolytic cell 10 is connected to a metering pump 14, which has a supernatant overflow outlet pipe above it. The metering pump 14 precisely controls the amount of ammonium salt or phosphate added to match the ammonia nitrogen to phosphate phosphorus molar ratio in the water to 1. The effluent from the suction pump 9 and the metering pump 14 flows upward from below the electrodes through the electrode plate area. The effluent from the micro-electrolysis anaerobic dynamic membrane bioreactor system, using the magnesium anode 12 and the stainless steel cathode 11, provides magnesium ions and hydroxide ions to generate struvite crystals. This system has several advantages, including struvite preferentially depositing near the cathode 11 for easy separation and dehydration, no suspended solids in the water for high-purity struvite, the ability to oxidize some recalcitrant organic matter to reduce subsequent treatment costs, the ability to utilize renewable energy sources such as wind and solar power for low cost, and the generation of hydrogen as a high-value byproduct to further increase revenue and reduce costs.

[0035] The aerobic activated sludge degradation system includes an aeration tank 15, which receives the effluent after electrochemical struvite crystallization and sedimentation treatment. Sufficient dissolved oxygen is provided to the tank through air aeration, enabling aerobic microorganisms to remove residual organic matter and further purify the water. The aeration tank 15 is connected to a secondary sedimentation tank 16, which receives the mixed liquor treated in the aeration tank 15. A return pump 17 is connected to the secondary sedimentation tank 16, with its other end connected to the aeration tank 15. The return pump 17 returns the settled activated sludge to the aeration tank 15, replenishing the microbial population and maintaining the stable operation of the aerobic treatment system. In the secondary sedimentation tank 16, the aerated wastewater undergoes sludge-water separation, causing the activated sludge to settle. The supernatant is then used as treated effluent, meeting discharge standards or for further reuse.

[0036] This invention also provides a method for treating high-concentration suspended organic wastewater that can simultaneously recover carbon, nitrogen, phosphorus, and hydrogen. The method utilizes the aforementioned device for treating high-concentration suspended organic wastewater that can simultaneously recover carbon, nitrogen, phosphorus, and hydrogen, and includes the following steps:

[0037] Step 1: First, high-concentration suspended organic wastewater is transported to anaerobic tank 1 through inlet pump 5 for anaerobic digestion treatment. At the same time, the biogas circulation blower 20 is used to aerate and maintain a uniform mixing state in the anaerobic tank. The low-cost carbon electrode micro-electrolysis unit 19 is controlled by oxidation-reduction potentiometer 3 to supply a small amount of oxygen and hydrogen to anaerobic tank 1. Then, the treated anaerobic sludge mixture is transported to membrane tank 6 through mixed liquor circulation pump 4. The low-cost micro-mesh filter membrane 7 with a dynamic sludge layer on its surface is used for sludge-water separation. The remaining sludge is discharged through sludge discharge pump 8, and the biogas is collected and utilized through biogas bag 2.

[0038] The micro-electrolysis unit uses inexpensive 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 inexpensive micro-mesh filter membrane is 5-15 L / m³. 2 / d; The micro-electrolysis unit operates automatically and intermittently based on the fluctuation of the oxidation-reduction potential in the anaerobic tank between -400mV and -150mV.

[0039] Step 2: The effluent from the micro-mesh filter membrane 7 in Step 1 is pumped into the electrolytic cell 10 by the suction product water pump 9. An appropriate amount of ammonium salt or phosphate is added to the electrolytic cell 10 by the metering pump 14 to match the molar ratio of ammonia nitrogen to phosphate phosphorus in the water to 1. The effluent from the suction product water pump 9 and the metering pump 14 flows upward from the bottom of the electrode through the electrode plate area. Struvite crystals are formed near the anode 12 and precipitate to the bottom for collection and utilization through the recovery system. Near the cathode 11, the recalcitrant organic matter is oxidized to produce hydrogen gas, which is collected and utilized through 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, and the anode 12 is a magnesium plate. The hydraulic residence 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 from Step 2 is flowed into the aeration tank 15 through the supernatant overflow 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 mixture is then passed into the secondary sedimentation tank 16 for solid-liquid separation. Part of the precipitated sludge is 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 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 is as follows: total suspended solids 23.5 g / L, volatile suspended solids 20.8 g / L, total COD 24.6 g / L, dissolved 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 wastewater from the pig farm was treated using a micro-electrolysis anaerobic dynamic membrane bioreactor system, with a hydraulic retention time of 3 days, a sludge retention time of 50 days, a temperature of room temperature, and a membrane flux of 12 L / m³. 2 / d, the micro-electrolysis unit (carbon brush electrode spacing 1cm, voltage 1.5V), operating under automatic intermittent oxygen and hydrogen supply conditions with the oxidation-reduction potential in anaerobic tank 1 fluctuating between -400mV and -150mV as the standard, achieves an average effluent COD of 1250mg / L (average removal rate as high as 94.9%), average ammonia nitrogen of 435mg / L, and average orthophosphorus of 128mg / L (some organic nitrogen and phosphorus are converted into ammonia nitrogen and orthophosphorus under anaerobic conditions, hence the effluent is higher than the influent), average total nitrogen of 440mg / L, average total phosphorus of 130mg / L, no suspended solids, and an average biogas yield of 10.7m³. 3 / m 3 The treated water had an average methane content of 70% and a methane recovery rate of 0.32 m³. 3 / kg COD.

[0046] An electrochemical struvite crystallization and precipitation system was used to treat the effluent from the aforementioned micro-electrolysis anaerobic dynamic membrane bioreactor system. Under operating conditions including a magnesium plate for anode 12, a nickel-plated stainless steel plate for cathode 11, a hydraulic retention time of 5 h, an electrode voltage of 1.5 V, an electrode spacing of 1 cm, and an added phosphorus concentration of 835 mg / L (to meet the ammonia nitrogen and phosphorus molar ratio required for struvite precipitation), the effluent showed an average ammonia nitrogen of 5 mg / L, an average total nitrogen of 8 mg / L, an average phosphorus concentration of 4 mg / L, an average total phosphorus concentration of 5 mg / L, and an average COD of 1120 mg / L. The recovered struvite purity reached 96.3%, and the struvite recovery rate was 7.5 kg / m³. 3 Water treatment, hydrogen recovery rate 0.1m³ 3 / m 3 Water treatment.

[0047] When the effluent from the electrochemical struvite crystallization and sedimentation system was treated using an aerobic activated sludge degradation system, under 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 COD of the effluent was 310 mg / L, the average ammonia nitrogen was 2 mg / L, the average total nitrogen was 5 mg / L, the average phosphorus was 1 mg / L, and the average total phosphorus was 2 mg / L. These results were significantly better than the requirements of the National Standard for Pollutant Discharge from Livestock and Poultry Farming (GB 18596-2001) and the relevant local emission standards.

[0048] Based on the process parameters and operational results of this embodiment, the wastewater from the pig farm (1000m³) was treated. 3 / d) Conduct engineering design and cost-benefit analysis of a combined technology scheme of micro-electrolysis anaerobic dynamic membrane bioreactor-electrochemical struvite crystallization sedimentation-aerobic activated sludge degradation. The volumes of the micro-electrolysis anaerobic dynamic membrane bioreactor, the electrochemical struvite crystallization sedimentation reactor, and the aerobic activated sludge reactor are 3000 m³ / s. 3 208m 3 208m 3 The reinforced concrete structure costs 1000 yuan / m². 3 Based on a 50-year service life and depreciation calculation, the total investment cost of the reactor is 3.417 million yuan, and the depreciation operating cost is 0.2 yuan / m³. 3 The nonwoven filter membrane has an area of ​​3500 m². 2 Based on a cost of 30 yuan / m 2 Based on a 3-year depreciation calculation, the investment cost of the non-woven filter membrane is 105,000 yuan, and the depreciation and operating cost is 0.1 yuan / m³. 3 The total investment cost for water pumps, fans, micro-electrolysis units, and pipe fittings is 300,000 yuan. The operating cost, calculated based on a 10-year depreciation period, is 0.1 yuan / m³. 3 The power consumption of the micro-electrolysis anaerobic dynamic membrane bioreactor, electrochemical struvite crystallization precipitation, and aerobic activated sludge degradation is 0.4 kWh / m³, respectively.3 2.2kWh / m 3 0.5kWh / m 3 With an electricity price of 0.7 yuan / kWh, the total electricity cost is 2.2 yuan / m³. 3 The magnesium anode consumption is 0.75 kg / m³. 3 Based on a cost of 20 yuan / kg, the operating cost of magnesium anodes is 15 yuan / m³. 3 The added phosphorus content is 0.84 kg / m³. 3 Based on a cost of 49 yuan / kg, the additional operating cost of orthophosphorus is 41 yuan / m³. 3 Labor and other operating costs totaled 0.45 yuan / m². 3 Based on the above cost calculations, the total investment cost of the project is 3.82 million yuan, equivalent to 3,820 yuan / m². 3 The total operating cost of the project is 59 yuan / m² / d. 3 Methane production was 7.5 m³. 3 / m 3 At the market price of 0.7 yuan / m 3 The calculated revenue from methane is 5.2 yuan / m³. 3 The yield of struvite is 7.5 kg / m³. 3 Based on a market price of 7.7 yuan / kg, the profit from bird droppings is 58 yuan / m³. 3 Hydrogen production was 0.1 m³. 3 / m 3 At market price of 3 yuan / m 3 The calculated profit from hydrogen is 0.3 yuan / m³. 3 Based on the above calculations, the total revenue for the project is 63.5 yuan / m². 3 The net profit after deducting total operating costs is 4.5 yuan / m². 3 The investment cost recovery period is 2.3 years, which shows that the combined technology of micro-electrolysis anaerobic dynamic membrane bioreactor-electrochemical struvite crystallization precipitation-aerobic activated sludge degradation has good technical and economic advantages.

[0049] Comparative Example 1

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

[0051] The effluent from the completely mixed anaerobic digester + centrifugal dewatering system was treated using a chemical struvite crystallization and precipitation system. Under operating conditions including the addition of 2842 mg / L magnesium chloride hexahydrate and 806 mg / L orthophosphate (to meet the ammonia nitrogen and orthophosphate molar ratio required for struvite precipitation) and a hydraulic retention time of 5 h, the effluent showed average ammonia nitrogen of 4 mg / L, average total nitrogen of 9 mg / L, average orthophosphate of 6 mg / L, average total phosphorus of 8 mg / L, average COD of 4980 mg / L, and average suspended solids of 3140 mg / L. The struvite purity recovered was 80.3%, and the struvite recovery rate was 7.4 kg / m³. 3 Water treatment.

[0052] The effluent from the aforementioned chemical struvite crystallization and sedimentation system was treated using an aerobic activated sludge degradation system. Under conditions of a hydraulic retention time of 16 hours, a sludge retention time of 8 days, and dissolved oxygen not less than 2 mg / L, the effluent had an average COD of 367 mg / L, an average ammonia nitrogen of 2 mg / L, an average total nitrogen of 6 mg / L, an average orthophosphorus of 2 mg / L, and an average total phosphorus of 5 mg / L, which are better than the corresponding requirements of the National Standard for Pollutant Discharge from Livestock and Poultry Farming (GB 18596-2001).

[0053] Based on the process parameters and operational results of Comparative Example 1, the wastewater (1000m³) from this pig farm was analyzed. 3 / d) Engineering design and cost-benefit analysis of a combined technology scheme of completely mixed anaerobic digestion + centrifugal dewatering - chemical struvite crystallization sedimentation - aerobic activated sludge degradation. The volumes of the completely mixed anaerobic digester, the chemical struvite crystallization sedimentation reactor, and the aerobic activated sludge reactor are 20,000 m³ each. 3 209m 3 669m 3 The reinforced concrete structure costs 1000 yuan / m². 3 Based on a 50-year service life and depreciation calculation, the total investment cost of the reactor is 20.878 million yuan, and the depreciation operating cost is 1.14 yuan / m³. 3 The total investment cost for water pumps, fans, centrifuges, and pipe fittings was 406,000 yuan. The operating cost, calculated based on a 10-year depreciation period, is 0.11 yuan / m³. 3 The power consumption for completely mixed anaerobic digestion + centrifugal dewatering, chemical struvite crystallization and sedimentation, and aerobic activated sludge degradation is 0.2 kWh / m³. 3 0.1kWh / m 3 2kWh / m 3With an electricity price of 0.7 yuan / kWh, the total electricity cost is 1.6 yuan / m³. 3 The magnesium chloride consumption was 2.84 kg / m³. 3 Based on a cost of 5.6 yuan / kg, the operating cost of magnesium chloride is 15.8 yuan / m³. 3 The added phosphorus content is 0.81 kg / m³. 3 Based on a cost of 49 yuan / kg, the additional operating cost of orthophosphorus is 39.3 yuan / m³. 3 Labor and other operating costs totaled 0.45 yuan / m². 3 Based on the above cost calculations, the total investment cost of the project is 21.28 million yuan, equivalent to 21,280 yuan / m². 3 The total operating cost of the project is 58.4 yuan / m². 3 Methane production was 4.7 m³. 3 / m 3 At the market price of 0.7 yuan / m 3 The calculated revenue from methane is 3.3 yuan / m³. 3 The yield of struvite is 7.2 kg / m³. 3 Based on a market price of 7.7 yuan / kg, the profit from bird droppings is 55.8 yuan / m³. 3 Based on the above calculations, the total revenue for the project is 59.1 yuan / m². 3 The net profit after deducting total operating costs is 0.7 yuan / m². 3 The investment cost recovery period is 89.3 years.

[0054] The data above shows that the combined technology scheme of micro-electrolysis anaerobic dynamic membrane bioreactor-electrochemical struvite crystallization precipitation-aerobic activated sludge degradation in Example 1 is significantly more economical than the traditional combined technology scheme of completely mixed anaerobic digestion + centrifugal dewatering-chemical struvite crystallization precipitation-aerobic activated sludge degradation in Comparative Example 1.

[0055] Therefore, this invention employs the aforementioned wastewater treatment device and method for high-concentration suspended organic wastewater 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., phosphorus phosphate) in the wastewater into struvite and generate hydrogen for recycling. The aerobic activated sludge degradation system can remove residual organic matter in the wastewater to achieve compliant discharge, ultimately achieving a win-win situation for both 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 and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions 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 in that: It includes 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 to the electrochemical struvite crystallization and precipitation system, and the electrochemical struvite crystallization and precipitation system is connected to the aerobic activated sludge degradation system. The micro-electrolysis anaerobic dynamic membrane bioreactor system includes an anaerobic tank, which is connected to a biogas bag and an inlet pump. The anaerobic tank is also connected to a biogas circulation aerator and a low-cost carbon electrode micro-electrolysis unit. An oxidation-reduction potentiometer is installed in the anaerobic tank, and both the oxidation-reduction potentiometer and the low-cost carbon electrode micro-electrolysis unit are connected to a controller. The micro-electrolysis anaerobic dynamic membrane bioreactor system also includes a membrane tank, which contains an inexpensive micro-mesh filter membrane with a dynamic sludge layer attached to its surface. A sludge discharge pump is installed at the bottom of the membrane tank, and the top of the membrane tank is connected to a biogas bag. The electrochemical struvite crystallization and precipitation system includes a fluidized bed electrolytic cell, which is connected to a hydrogen bag. A struvite precipitation and recovery component is installed at the bottom of the electrolytic cell. The electrolytic cell is connected to a suction pump and a metering pump, and a supernatant overflow outlet pipe is provided above it. The anaerobic tank is connected to the membrane tank via a mixed liquor circulation pump, and an overflow return water pipe is also provided between the anaerobic tank and the membrane tank. The membrane tank is connected to the electrochemical struvite crystallization and precipitation system via a pump for pumping permeate. The aerobic activated sludge degradation system includes an aeration tank 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.

2. A method for treating high-concentration suspended organic wastewater capable of simultaneous recovery of carbon, nitrogen, phosphorus, and hydrogen, comprising the high-concentration suspended organic wastewater treatment device capable of simultaneous recovery of carbon, nitrogen, phosphorus, and hydrogen described in claim 1, characterized in that: Includes the following steps: Step 1: First, high-concentration suspended organic wastewater is pumped to the anaerobic tank for anaerobic digestion. At the same time, a biogas circulating blower is used to maintain a uniform mixing state in the anaerobic tank, and a low-cost carbon electrode micro-electrolysis unit is controlled by an oxidation-reduction potentiometer to supply a small amount of oxygen and hydrogen to the anaerobic tank. Then, the treated anaerobic sludge mixture is pumped to the membrane tank through a mixed liquor circulation pump. A low-cost micro-mesh filter membrane with a dynamic sludge layer on its surface is used for sludge-water separation. The remaining sludge is discharged through a sludge discharge pump, and the biogas is collected and utilized through a biogas bag. Step 2: The effluent from the inexpensive micro-mesh filter membrane in Step 1 is pumped into the electrolytic cell using a pumping permeate pump. An appropriate amount of ammonium salt or phosphate is added to the electrolytic cell using a metering pump to match the ammonia nitrogen and phosphate phosphorus molar ratio in the water to 1. The effluent from both the pumping permeate pump and the metering pump flows upward from below the electrodes through the electrode plate area. Struvite crystals are formed near the anode and then precipitate to the bottom and are collected and utilized through a recycling system. Near the cathode, recalcitrant organic matter is oxidized to produce hydrogen gas, which is collected and utilized through a hydrogen gas bag. Step 3: The supernatant from Step 2 is discharged into the aeration tank through the supernatant overflow pipe. The 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 mixture is then fed into the secondary sedimentation tank for solid-liquid separation. Part of the precipitated sludge is returned to the aeration tank to maintain the microbial concentration, and the remaining sludge is discharged from the system.

3. The method for treating high-concentration suspended organic wastewater capable of simultaneous recovery of carbon, nitrogen, phosphorus, and hydrogen according to claim 2, characterized in that: In step one, the micro-electrolysis unit uses inexpensive carbon brush electrodes with an electrode spacing of 1. 3cm, electrode voltage 1.2 2V; the hydraulic retention time in the anaerobic tank is 1. 5 days, sludge retention time is 30 days 100 days, at room temperature; the flux of the inexpensive micromembrane filter is 5. 15L / m 2 / d; The micro-electrolysis unit uses the redox potential in the anaerobic tank at... 400mV to Fluctuations within 150mV are the standard for automatic intermittent operation.

4. The method for treating high-concentration suspended organic wastewater capable of simultaneous recovery of carbon, nitrogen, phosphorus, and hydrogen according to claim 3, characterized in that: In step two, the cathode of the electrolytic cell is a nickel-plated stainless steel plate or a platinum-plated carbon plate, and the anode is a magnesium plate. The hydraulic residence time of the electrolytic cell is 1 hour. 5 hours, electrode voltage 1.5 3V, electrode spacing 0.5 1.5cm.

5. The method for treating high-concentration suspended organic wastewater capable of simultaneous recovery of carbon, nitrogen, phosphorus, and hydrogen according to claim 4, characterized in that: The hydraulic retention time in the aeration tank in step three is 6 seconds. 24h, sludge retention time is 10 Dissolved oxygen should be no less than 2 mg / L for 20 days.

Images