Hydrogen autotrophic nitrogen removal device

Abstract

The invention discloses a hydrogen autotrophic nitrogen removal device, and belongs to the field of biological nitrogen removal. The solubility of hydrogen in water is low, so that the rate of hydrogen autotrophic nitrogen removal reaction is limited. According to the invention, a hydrogen autotrophic percolation denitrification reactor is constructed in a mode that wastewater, hydrogen and carbon dioxide flow downwards at the same time, the hydrogen is a continuous phase, and the wastewater is a dispersed phase, which is equivalent to raining in a hydrogen atmosphere, so that gas-liquid mass transfer among the hydrogen, the wastewater and denitrification microorganisms can be greatly increased. The method is simple to operate, and only needs to regulate and control the flow of hydrogen and carbon dioxide without adding any medicine. The method can be used for deep denitrification of domestic sewage and industrial wastewater.

Description

Technical Field

[0001] The present invention relates to the technical field of biological denitrification, and particularly relates to a hydrogen autotrophic denitrification device and method. Background Art

[0002] The cost of using hydrogen mainly lies in hydrogen storage rather than hydrogen production. Hydrogen autotrophic denitrification can instantaneously utilize the low-pressure hydrogen generated by electrolyzing water under a relatively low hydrogen pressure, enabling the immediate production and use of hydrogen.

[0003] The existing denitrification processes generally adopt heterotrophic denitrification processes, using organic carbon sources as electron donors. This not only has a high cost but also causes secondary pollution of excessive effluent COD and releases carbon dioxide. Moreover, sulfur autotrophic and iron autotrophic denitrification in autotrophic denitrification still produce secondary pollutants such as sulfates and iron ions. Hydrogen autotrophic denitrification is clean and pollution-free, and can be coupled with photovoltaic power generation and electrolytic hydrogen production technologies. Hydrogen does not need to be stored, achieving the immediate production and use of hydrogen. However, the low solubility of hydrogen in water leads to a high hydrogen content in the tail gas, low hydrogen utilization rate, and low denitrification rate. The safety problem of the tail gas also needs to be solved. Summary of the Invention

[0004] To solve the above problems, the present invention provides a hydrogen autotrophic denitrification device, which includes a hydrogen gas source, a carbon dioxide gas source, a hydrogen control valve, a carbon dioxide control valve, a hydrogen flowmeter, a carbon dioxide flowmeter, a reactor, a water bath barrel, a water pump, and a heating and constant temperature device; the hydrogen gas source and the carbon dioxide gas source are regulated by the hydrogen valve and the carbon dioxide valve and then converge into the same pipeline and enter the top of the reactor. The flow rates of carbon dioxide and hydrogen can be observed in real time through the hydrogen flowmeter and the carbon dioxide flowmeter; the wastewater flows into the water bath barrel, is heated by the heating and constant temperature device and controlled at a certain temperature, and the water pump pumps the wastewater in the water bath barrel to the top of the reactor; after the wastewater reacts with hydrogen, carbon dioxide, and microorganisms in the reactor, it is discharged from the bottom of the reactor under the action of gas pressure; the hydrogen autotrophic denitrification device provided by the present invention can construct a hydrogen autotrophic percolation denitrification reactor in a way that the wastewater, hydrogen, and carbon dioxide flow downward simultaneously. Hydrogen is the continuous phase, and the wastewater is the dispersed phase, which is equivalent to raining in a hydrogen atmosphere, greatly increasing the gas-liquid mass transfer between hydrogen, wastewater, and denitrifying microorganisms; the present invention can control the temperature of hydrogen autotrophic denitrification at an appropriate level and at the same time ensure that the temperature of the wastewater entering the reactor is also in a relatively appropriate range; the present invention is simple to operate, only requiring the regulation of the hydrogen and carbon dioxide flow rates without adding any external drugs.

[0005] A hydrogen autotrophic denitrification device includes a hydrogen gas source, a carbon dioxide gas source, a hydrogen control valve, a carbon dioxide control valve, a hydrogen flowmeter, a carbon dioxide flowmeter, a reactor, a water bath barrel, a water pump, and a heating and constant temperature device.

[0006] The hydrogen gas source can come from electrolysis of water, methane cracking, etc., and the carbon dioxide gas source can come from a pure carbon dioxide cylinder.

[0007] The carbon dioxide flowmeter needs to accurately measure low-flow carbon dioxide, and the hydrogen flowmeter needs to be calibrated by the water displacement method.

[0008] The reactor needs to be able to withstand a certain pressure (0.05 - 0.2 Mpa), including a top liquid distributor, a gas inlet, a middle packing, and a bottom gas-liquid outlet. The liquid distributor can evenly distribute the wastewater above the packing. The gas inlet admits a mixture of hydrogen and carbon dioxide. The packing is one or several of a porous material woven from polyester fiber, gravel, and sponge. The particle size of the packing is about 1 / 20 of the reactor diameter, the thickness of the packing layer is about 9 / 10 of the reactor height, the pore diameter of the packing is about 200 - 600 μm, the packing can adsorb a large amount of hydrogen autotrophic denitrifying bacteria, and the bottom gas-liquid outlet is connected to a pipe flowing out of the water bath bucket. The water column in the pipe is not lower than the reactor height. Controlling the height of this water column can regulate the pressure in the reactor, and the overall density of the reactor is greater than that of water.

[0009] The water bath bucket can withstand a temperature below 40°C, and the water level is controlled below the reactor height.

[0010] The heating and constant temperature device is characterized in that it can control the temperature of the wastewater in the water bath bucket, and the control range is 25 - 30°C.

[0011] The gas and liquid flowing out of the gas-liquid outlet of the reactor need to be manually measured for total nitrogen concentration, pH, and hydrogen concentration, so as to adjust the influent flow rate, carbon dioxide flow rate, and hydrogen flow rate. Description of the Drawings

[0012] Figure 1, Schematic diagram of the hydrogen autotrophic denitrification device of the present invention.

[0013] Figure 2, Results of the cyclic startup of the hydrogen autotrophic denitrification device of the present invention.

[0014] Figure 3, Influence of temperature on the denitrification rate of the hydrogen autotrophic denitrification device of the present invention.

[0015] Figure 4, Continuous operation data of the hydrogen autotrophic denitrification device of the present invention. Detailed Embodiments

[0016] The present invention will be further described below in conjunction with the drawings and specific embodiments.

[0017] Embodiment 1 A hydrogen autotrophic denitrification device as shown in Figure 1, which includes a hydrogen generator 1, a carbon dioxide cylinder 8, a hydrogen flow control valve 2, a carbon dioxide flow control valve 11, a carbon dioxide bubble flowmeter 9, a reactor 6, a water bath bucket 5, a heating rod 7, and a peristaltic pump 4; The hydrogen generated by the hydrogen generator 1 and the carbon dioxide generated by the carbon dioxide cylinder 8 are regulated by the hydrogen valve 2 and the carbon dioxide valve 11 and then converge into the same pipeline. The hydrogen generator 1 can directly display the hydrogen flow rate, and the carbon dioxide flow rate is read by observing the carbon dioxide bubble bubbling rate through the bubble flowmeter 9. The carbon dioxide and hydrogen flow rates can be observed in real time through the hydrogen generator 1 and the carbon dioxide bubble flowmeter 9; The wastewater flows into the water bath bucket 5, is heated by the heating and constant temperature device and controlled at a certain temperature, and the peristaltic pump 4 pumps the wastewater in the water bath bucket into the top of the reactor 6; After the wastewater reacts with hydrogen, carbon dioxide, and microorganisms in the reactor, it is discharged from the bottom of the reactor under the action of gas pressure; The reactor can withstand a certain pressure (0.2 Mpa), is made of plexiglass, has an inner diameter of 10 cm, a height of 1 m, is connected by a flange at the top, and is sealed with a rubber ring; The reactor includes a top liquid distributor, a gas port, a middle filler, and a bottom gas-liquid outlet. The liquid distributor can evenly distribute the wastewater above the filler. The gas inlet is introduced with a mixture of hydrogen and carbon dioxide. The filler is a porous material woven from polyester fiber material. The filler particle size is about 5 mm of the reactor diameter, the filler layer thickness is about 0.9 m, and the filler pore diameter is about 400 μm. The filler can adsorb a large amount of hydrogen autotrophic denitrifying bacteria. The bottom gas-liquid outlet is connected to a pipeline flowing outside the water bath bucket. The water column height in the pipeline is 1 m, and the pressure in the reactor is controlled at 0.1 bar. The overall density of the reactor is greater than that of water, and it can be vertically placed in the water bath bucket and stand firm; The temperature of the wastewater in the water bath bucket is controlled at 30°C by the heating rod; When it is detected that the pH of the effluent is lower than 7, the carbon dioxide flow rate is reduced. When it is detected that the pH of the effluent is higher than 9, the carbon dioxide flow rate is increased; When it is detected that the total nitrogen in the effluent is higher than the discharge standard, the influent flow rate is reduced; When it is detected that the hydrogen concentration at the outlet is higher than 4%, the hydrogen flow rate is reduced.

[0018] Example 2 500 mL of anaerobic sludge from a sewage treatment plant was inoculated into the reactor. The sludge was thoroughly mixed with the packing material. A peristaltic pump was used to pump the simulated nitrate-nitrogen wastewater from the inlet water tank to the top of the reactor and flow through the reactor in the form of percolation. Hydrogen and carbon dioxide entered from the top. The hydrogen flow rate was 50 mL / min and the carbon dioxide flow rate was 3 mL / min. The volume of the simulated nitrate-nitrogen wastewater in the inlet water tank was 10 L. The effluent flowed back to the inlet water tank from the bottom outlet. An additional pore was left in the inlet water tank to discharge the waste gas out of the laboratory. Such cyclic cultivation was carried out to maximize the biomass in the reactor. The concentrations of nitrate-nitrogen and nitrite-nitrogen in the inlet water tank were detected at regular intervals. When the concentrations were too low, sodium nitrate was added to the inlet water tank and thoroughly mixed. The experimental results are shown in Figure 2. Sodium nitrate was added to the inlet water tank on the 4th and 6th days to increase the nitrate-nitrogen concentration. From the data of 0 - 4 days, 4 - 6 days, and 6 - 10 days, the nitrate-nitrogen removal rate was stable and the nitrite-nitrogen could be completely removed, indicating the successful startup of the reactor.

[0019] Example 3 The reactor was temperature-controlled by heating the reactor with a heating rod in a water bath. The relationship between the temperature and the denitrification rate of the reactor is shown in Figure 3. When the reactor temperature was 25°C, the denitrification rate was about 700 g N / (m 3 ·d). When the temperature was 27 - 29°C, the denitrification rate was about 1000 g N / (m 3 ·d). Therefore, the denitrification performance of the hydrogen autotrophic denitrification reactor was greater when the temperature was in the range of 27 - 29°C than when the temperature was below 25°C. When the temperature was not in the optimal temperature range for the hydrogen autotrophic bacteria to maintain the denitrification rate, the denitrification rate of the reactor would decrease significantly.

[0020] Example 4 The reactor was continuously operated under the following conditions: the influent nitrate-nitrogen concentration was controlled above 1000 mg N / L, the reactor temperature was controlled at 30°C by heating in a water bath, the liquid flow rate was controlled at 0.4 - 0.5 L / h, the hydrogen flow rate was 50 mL / min, and the carbon dioxide flow rate was 20 - 30 mL / min. The operation data of the reactor are shown in Figure 4. The denitrification rate of the reactor increased significantly, reaching a maximum of 1857 g N / (m 3 ·d). The average denitrification rate from the 12th to the 14th day was about 1650 g N / (m 3·d), the hydrogen concentration at the waste gas outlet can reach less than 4%, and even reach 0. On the 5th, 6th, and 7th days, due to the lag in CO2 regulation, the denitrification rate decreased, but it increased rapidly after adjustment, indicating that the reactor has good shock resistance. On the 12th day, hydrogen was completely utilized. At this time, the nitrogen concentration at the outlet was 89%, and the other gases might be water vapor, indicating that the final product of this hydrogen autotrophic denitrification device was harmless nitrogen.

[0021] The above-described embodiments only represent the preferred embodiments of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the invention patent, several deformations and improvements made all fall within the protection scope of the invention patent. Therefore, the protection scope of the invention patent shall be subject to the appended claims.

Claims

1. A hydrogen autotrophic denitrification device, characterized in that, It includes a hydrogen gas source, a carbon dioxide gas source, a hydrogen control valve, a carbon dioxide control valve, a hydrogen flowmeter, a carbon dioxide flowmeter, a reactor, a water bath bucket, a water pump, and a heating and constant temperature device; the hydrogen gas source and the carbon dioxide gas source are regulated by the hydrogen valve and the carbon dioxide valve and then converge on the same pipeline and enter the top of the reactor. The flow rates of carbon dioxide and hydrogen can be observed in real time through the hydrogen flowmeter and the carbon dioxide flowmeter; the wastewater flows into the water bath bucket and is heated by the heating and constant temperature device to be controlled at a certain temperature, and the water pump pumps the wastewater in the water bath bucket into the top of the reactor; after the wastewater reacts with hydrogen, carbon dioxide, and microorganisms in the reactor, it is discharged from the bottom of the reactor under the action of gas pressure.

2. The hydrogen autotrophic denitrification device according to claim 1, characterized in that, The hydrogen gas source can come from electrolyzed water, methane cracking, etc., and the carbon dioxide gas source can come from a high-purity carbon dioxide steel cylinder, etc.

3. The hydrogen autotrophic denitrification device according to claim 1, characterized in that, The carbon dioxide flowmeter needs to accurately measure low-flow carbon dioxide, and the hydrogen flowmeter needs to be calibrated by the water displacement method.

4. The hydrogen autotrophic denitrification device according to claim 1, characterized in that, The reactor needs to be able to withstand a certain pressure (0.05~0.2 Mpa), and includes a top liquid distributor, a gas inlet, a middle packing, and a bottom gas-liquid outlet. The liquid distributor can evenly distribute the wastewater above the packing. The gas inlet is for introducing a mixture of hydrogen and carbon dioxide. The packing is one or several of a porous material woven from polyester fiber material, gravel, and sponge. The particle size of the packing is about 1 / 10~1 / 20 of the reactor diameter, the thickness of the packing layer is about 8 / 10~9 / 10 of the reactor height, the pore diameter of the packing is about 200~600 μm, the packing can adsorb a large amount of hydrogen autotrophic denitrifying bacteria, the bottom gas-liquid outlet is connected to a pipeline flowing out of the water bath bucket, and the water column in the pipeline is not lower than the reactor height. Controlling the height of this water column can regulate the pressure in the reactor, and the overall density of the reactor is greater than that of water.

5. The hydrogen autotrophic denitrification device according to claim 1, characterized in that, The water bath bucket can withstand a temperature below 40°C, and the water level is controlled below the height of the reactor as described in claim 4.

6. The hydrogen autotrophic denitrification device according to claim 1, characterized in that, The heating and constant temperature device is characterized in that it can control the temperature of the wastewater in the water bath bucket, and the control range is 25~30°C.

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