Modularized artificial wetland system for synchronous heating and carbon supplementation by using biological fermentation

Abstract

The invention relates to the technical field of constructed wetlands. The invention provides a modular artificial wetland system for synchronous heating and carbon supplementation by using biological fermentation. The modular artificial wetland system comprises an artificial wetland purification module, a fermentation heating module, a carbon source release module and a control module. According to the invention, the constructed wetland system is designed into a plurality of functional modules, and each module independently exerts a specific function and can be flexibly combined and adjusted according to actual requirements, so that effective coordination of the whole process of heating, carbon supplement and purification is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of artificial wetlands, and in particular to a modular artificial wetland system utilizing biological fermentation for synchronous heat generation and carbon replenishment. Background Art

[0002] In winter, due to the significant decrease in temperature, the activity of microorganisms in artificial wetlands generally decreases. This decrease in activity directly affects the metabolic process of microorganisms, especially the growth and reproduction of denitrifying microorganisms, resulting in a significant limitation of their denitrification capacity. In the denitrification process, microorganisms need sufficient carbon sources to promote the reduction reaction of nitrates. However, in cold environments, the secretion of small molecular organic carbon by plant roots and the decomposition process of plant litter in wetlands are significantly reduced. Therefore, there is often a problem of insufficient carbon source in winter wetlands. Therefore, a new method is urgently needed that can not only provide sufficient carbon source in cold environments, but also maintain the activity of microorganisms by raising the ambient temperature. By providing heat and carbon source at the same time, the growth of denitrifying microorganisms can be effectively promoted, thereby significantly improving the nitrogen removal capacity of artificial wetlands in winter and ensuring the sustainability and efficiency of water purification effects. Summary of the invention

[0003] The purpose of the present invention is to provide a modular artificial wetland system that utilizes biological fermentation for simultaneous heat generation and carbon replenishment. The artificial wetland system is designed as a plurality of functional modules, each module independently performs a specific function, and can be flexibly combined and adjusted according to actual needs to achieve effective coordination of the whole process of "heat generation - carbon replenishment - purification".

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] The present invention provides a modular artificial wetland system for synchronously generating heat and replenishing carbon by using biological fermentation. The modular artificial wetland system comprises an artificial wetland purification module, a fermentation heating module, a carbon source releasing module and a control module.

[0006] Preferably, the artificial wetland purification module includes a nitrification zone and a denitrification zone;

[0007] The dissolved oxygen value in the nitrification zone is above 2 mg / L and the temperature is 15-35°C;

[0008] The water depth of the nitrification zone is 25-35 cm, and pebbles and gravels with a particle size of 1-3 cm are used as fillers, and the thickness of the fillers is 20-30 cm;

[0009] The dissolved oxygen value in the denitrification zone is 0.15-0.25 mg / L, and the temperature is 15-30°C;

[0010] The water depth of the denitrification zone is 45-55 cm, and crushed stone and gravel with a particle size of 2-5 cm are used as fillers, and the thickness of the fillers is 30-50 cm;

[0011] The denitrification zone is planted with wetland plants, the types of which are reeds, cattails or calamus; the density of the wetland plants is 15 to 25 plants / m 2 .

[0012] Preferably, the fermentation heating module comprises an outer shell and an insulation layer, the thickness of the insulation layer is 5 to 10 cm, and the volume of a single fermentation heating module is 80 to 120 m 3 The fermentation heating module utilizes organic matter such as kitchen waste, straw, and wetland plant litter to ferment and generate heat.

[0013] Preferably, the water body in the artificial wetland purification module and the fermentation heating module are connected by a heat exchange system.

[0014] Preferably, the carbon source release module is connected to the denitrification zone, and the carbon source release module includes the fermentation liquid produced in the fermentation heating module. During operation, the fermentation liquid is supplemented to the denitrification zone through the carbon source release module to maintain the C / N ratio in the denitrification zone at 5-7.

[0015] Preferably, the control module is used to monitor the temperature and C / N in real time, and start the fermentation heating module and the carbon source release module when the temperature is lower than the threshold value;

[0016] The control module includes a temperature sensor and a water quality monitor. The temperature sensor has a measurement range of -10 to 50°C and an accuracy of ±0.1°C. The water quality monitor is used to monitor the C / N in the denitrification zone.

[0017] The present invention provides a modular artificial wetland system that uses biological fermentation to generate heat and replenish carbon simultaneously, and the modular artificial wetland system includes an artificial wetland purification module, a fermentation heating module, a carbon source release module and a control module. The present invention designs the artificial wetland system into multiple functional modules, each module independently performs a specific function, and can be flexibly combined and adjusted according to actual needs to achieve effective coordination of the entire process of "heat generation-carbon replenishment-purification". BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The structural diagram of the artificial wetland system designed for the present invention, wherein ① is the nitrification zone, ② is the denitrification zone, ③ is the fermentation heating module, ④ is the heat exchange system, ⑤ is the carbon source release module, ⑥ is the temperature sensor, ⑦ is the water quality detector, and ⑧ is the fermentation liquid transmission pipeline. DETAILED DESCRIPTION

[0019] The present invention provides a modular artificial wetland system for synchronously generating heat and replenishing carbon by using biological fermentation. The modular artificial wetland system comprises an artificial wetland purification module, a fermentation heating module, a carbon source releasing module and a control module.

[0020] In the present invention, the artificial wetland purification module preferably includes a nitrification zone and a denitrification zone;

[0021] The dissolved oxygen value in the nitrification zone is preferably above 2 mg / L, and the temperature is preferably 15 to 35°C, more preferably 25 to 32°C;

[0022] The water depth of the nitrification zone is preferably 25 to 35 cm, more preferably 30 cm, and pebbles and gravels with a particle size of 1 to 3 cm are preferably used as fillers. The thickness of the fillers is preferably 20 to 30 cm, more preferably 25 cm;

[0023] The dissolved oxygen value of the denitrification zone is preferably 0.15 to 0.25 mg / L, more preferably 0.2 mg / L, and the temperature is preferably 15 to 30°C, more preferably 20 to 25°C;

[0024] The water depth of the denitrification zone is preferably 45 to 55 cm, more preferably 50 cm, preferably crushed stone and gravel with a particle size of 2 to 5 cm are used as fillers, and the thickness of the filler is preferably 30 to 50 cm, more preferably 40 cm;

[0025] The denitrification zone is planted with wetland plants, and the species of the wetland plants are preferably reeds, cattails or calamus; the density of the wetland plants is preferably 15 to 25 plants / m 2 , more preferably 20 plants / m 2 .

[0026] In the present invention, the fermentation heating module preferably includes a shell and an insulation layer, the thickness of the insulation layer is preferably 5 to 10 cm, more preferably 7 to 8 cm, and the volume of a single fermentation heating module is preferably 80 to 120 m 3 , more preferably 100m 3 The fermentation heating module utilizes organic matter such as kitchen waste, straw, and wetland plant litter to ferment and generate heat.

[0027] In the present invention, the water body in the artificial wetland purification module and the fermentation heating module are preferably connected by a heat exchange system.

[0028] In the present invention, the carbon source release module is preferably connected to the denitrification zone, and the carbon source release module includes the fermentation liquid produced in the fermentation heating module. During operation, the fermentation liquid is supplemented to the denitrification zone through the carbon source release module to maintain the C / N in the denitrification zone preferably at 5 to 7, and more preferably at 6.

[0029] In the present invention, the control module is used to monitor the temperature and C / N in real time, and start the fermentation heating module and the carbon source release module when the temperature is lower than the threshold value;

[0030] The control module preferably includes a temperature sensor and a water quality monitor. The temperature sensor has a measurement range of -10 to 50°C and an accuracy of ±0.1°C. The water quality monitor is used to monitor the C / N of the denitrification zone.

[0031] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0032] Example 1

[0033] The experiment was conducted in Beijing. Due to the low temperature in winter, the treatment efficiency of the tailwater of the sewage treatment plant is often affected by low temperature, especially the nitrogen removal rate is greatly reduced. To meet this challenge, the present invention designs and builds a modular artificial wetland system, which combines biological fermentation heating, carbon source supplementation and microbial activity enhancement technology to ensure the efficient operation of the wetland system under low temperature conditions, while achieving deep removal of nitrogen pollutants in the tailwater.

[0034] The specific construction steps are as follows:

[0035] Step 1: Design and construct wetland purification modules in different areas, including nitrification and denitrification areas. First, calculate the area of ​​artificial wetlands. The area of ​​wetlands is one of the key factors affecting the ability of wetlands to remove pollution. The larger the wetland area, the longer the hydraulic retention time, the lower the pollutant load per unit area, and the more stable the treatment effect. According to the provisions of the "Technical Guidelines for Artificial Wetland Water Purification", calculate the wetland area based on the recommended total nitrogen reduction load, ammonia nitrogen reduction load, and hydraulic load, and take the maximum value of the calculated results:

[0036] (1) Calculate the wetland area using the total nitrogen reduction load using the formula: A = W × (S 0 -S 1 ) / NA, where NA is the total nitrogen reduction load (g / m 2 / d), and the recommended value according to the "Guidelines for Artificial Wetland Water Purification Technology" is 0.4g / m 2 / d; W is the designed water volume of the artificial wetland (m 3 / d), 100m 3 / d;S 0 is the total nitrogen mass concentration of the artificial wetland influent (g / m 3 ), 18g / m 3 ; S 1 is the total nitrogen mass concentration of artificial wetland effluent (g / m 3 ), 2.0g / m 3Therefore, the artificial wetland area A = 4000m 2 .

[0037] (2) Calculate the wetland area using the ammonia nitrogen reduction load, using the formula: A = W × (S 0 -S 1 ) / NA, where NA is the ammonia nitrogen reduction load (g / m 2 / d), the recommended value is 0.2g / m 2 / d; W is the designed water volume of the artificial wetland (m 3 / d), 100m 3 / d;S 0 is the mass concentration of ammonia nitrogen in the artificial wetland influent (g / m 3 ), 8g / m 3 ; S1 is the mass concentration of ammonia nitrogen in the artificial wetland effluent (g / m 3 ), 0.5g / m 3 Therefore, according to the ammonia nitrogen reduction load, the artificial wetland area A = 3750m 2 .

[0038] (3) The hydraulic load is used to calculate the wetland area using the formula: A = W / HLR, where W is the designed water volume of the artificial wetland (m 3 / d), 100m 3 / d; HLR is the surface hydraulic load (m 3 / m 2 / d), the recommended value is 0.1m 3 / m 2 / d. Therefore, the wetland area is calculated based on the hydraulic load: A = 100 / 0.1 = 1000m 2 .

[0039] In summary, the wetland area is determined to be 4000m 2 .

[0040] The nitrification area and denitrification area are divided into zones. The nitrification area is 2500m 2 , water depth 30cm, volume 750m 3 , the filling material is pebbles and gravels (particle size 1-3cm, filling thickness 25cm); denitrification area: area 1500m 2 , water depth 50cm, volume 750m 3 The filler is crushed stone and gravel (particle size 2-5cm, filling thickness 40cm), and wetland plants such as reeds, cattails, and calamus are planted at 20 plants / ㎡, so the effective volume of the wetland is 750m 3 +750m 3 =1500m 3 . Hydraulic retention time HRT = V / W = 1500 / 100 = 15d.

[0041] Step 2: Install an independent fermentation heating module to ensure efficient and stable heat exchange with the wetland system.

[0042] The fermentation heating module is made of stainless steel with 5-10cm polyurethane foam as insulation layer. The volume of each fermentation module is 100m 3 Considering 15% buffer space, the effective volume of each fermenter is 85m 3 , can accommodate 4250kg of organic matter such as kitchen waste, straw, wetland plant litter, etc. Under the conditions of 80% fermentation efficiency and 3000kJ / kg heat production of organic matter, the total heat production of a single fermentation module is 10,200,000kJ. The efficiency of heat transfer from the fermentation module to the water body is 70%, so the designed effective heat production of a single fermentation module is 7,140,000kJ.

[0043] The daily heat dissipation of the wetland is calculated by the following formula: Q = h × A × ΔT × t, where h is the thermal conductivity, unit is W / (m 2 ·K); A is the wetland area, in m 2 ; ΔT is the difference between the water temperature and the ambient temperature, in degrees Celsius; t is the time, in seconds. In this embodiment, the thermal conductivity of the water-air interface is h = 20 W / (m 2 \K), the wetland area is 4000m 2 , temperature difference ΔT = Twater - Tenvironment = 20℃-5℃ = 15℃, time t = 24 hours × 3600 seconds / hour = 86400 seconds. It is calculated that the daily heat loss of the wetland is about 103,680,000 kJ. In order to meet the daily heat supplement demand, the number of fermentation modules required is: 103,680,000 / 7,140,000≈14.52. In order to ensure sufficient heat supply, 15 fermentation modules were finally selected. This design can not only meet the water heating needs, but also provide a certain buffering capacity to ensure the stability of the system in actual operation.

[0044] Step 3: Install a heat exchange system between the wetland water body and the fermentation module. The fermentation module transfers heat to the circulating water by heating water or through a heat exchanger. The hot water enters the heat exchanger through a pipe and indirectly contacts the wetland water body for heat transfer. The cooled hot water returns to the fermentation module through the return pipe for reheating.

[0045] Step 4: Set up the carbon source release module and connect it to the denitrification zone to ensure that the C / N ratio in the denitrification zone is 5-7.

[0046] The fermentation liquid produced in the fermentation module is pumped into the carbon source release module, and then the fermentation liquid is added to the denitrification area to maintain the C / N ratio at 5-7.

[0047] Step 5: Configure the control module to complete the intelligent integration of the system, monitor the temperature and C / N in real time, and automatically start the heating and carbon source modules when the temperature is below the threshold. Including temperature sensor: measuring range -10~50℃, accuracy ±0.1℃; water quality monitor: implement the monitoring of C / N in the denitrification area.

[0048] result:

[0049] In this embodiment, the concentration of ammonia nitrogen (NH4-N) is 10 g / m 3 , total nitrogen (TN) concentration is 18g / m 3 . Target daily processing capacity: 100m 3 / d. Water quality improvement target: ammonia nitrogen removal rate ≥ 90%; total nitrogen removal rate ≥ 75%. In winter, the system water temperature is maintained at 15-20℃.

[0050] As can be seen from the above embodiments, the present invention provides a modular artificial wetland system that uses biological fermentation for synchronous heat generation and carbon replenishment, and the modular artificial wetland system includes an artificial wetland purification module, a fermentation heating module, a carbon source release module and a control module. The present invention designs the artificial wetland system into multiple functional modules, each of which independently performs a specific function and can be flexibly combined and adjusted according to actual needs to achieve effective coordination of the entire process of "heat generation-carbon replenishment-purification".

[0051] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A modular artificial wetland system that uses biological fermentation to generate heat and replenish carbon simultaneously, characterized in that: The modular artificial wetland system comprises an artificial wetland purification module, a fermentation and heating module, a carbon source release module and a control module.

2. The modular artificial wetland system according to claim 1, characterized in that: The artificial wetland purification module includes a nitrification zone and a denitrification zone; The dissolved oxygen value in the nitrification zone is above 2 mg / L and the temperature is 15-35°C; The water depth of the nitrification zone is 25 to 35 cm, and pebbles and gravels with a particle size of 1 to 3 cm are used as fillers, and the thickness of the fillers is 20 to 30 cm; The dissolved oxygen value in the denitrification zone is 0.15-0.25 mg / L, and the temperature is 15-30°C; The water depth of the denitrification zone is 45-55 cm, and crushed stone and gravel with a particle size of 2-5 cm are used as fillers, and the thickness of the fillers is 30-50 cm; The denitrification zone is planted with wetland plants, the types of which are reeds, cattails or calamus; the density of the wetland plants is 15 to 25 plants / m 2 .

3. The modular artificial wetland according to claim 2, characterized in that: The fermentation heating module comprises an outer shell and an insulation layer, the thickness of the insulation layer is 5 to 10 cm, and the volume of a single fermentation heating module is 80 to 120 m 3 The fermentation heating module utilizes organic matter such as kitchen waste, straw, and wetland plant litter to ferment and generate heat.

4. The modular artificial wetland according to claim 3, characterized in that: The water body in the artificial wetland purification module and the fermentation heating module are connected by a heat exchange system.

5. The modular artificial wetland according to claim 4, characterized in that: The carbon source release module is connected to the denitrification zone. The carbon source release module includes the fermentation liquid produced by the fermentation heating module. During operation, the fermentation liquid is supplemented to the denitrification zone through the carbon source release module to maintain the C / N ratio in the denitrification zone at 5-7.

6. The modular artificial wetland according to claim 5, characterized in that: The control module is used to monitor the temperature and C / N in real time, and start the fermentation heating module and the carbon source release module when the temperature and C / N are lower than the threshold value; The control module includes a temperature sensor and a water quality monitor. The temperature sensor has a measurement range of -10 to 50°C and an accuracy of ±0.1°C. The water quality monitor is used to monitor the C / N in the denitrification zone.

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