Photovoltaic driving type integrated biological filter equipment and denitrification method thereof

Abstract

The invention discloses photovoltaic driving type integrated biological filter equipment and a denitrification method thereof, and relates to the technical field of biological filters, the biological filter equipment comprises a biological filter and a photovoltaic driving unit, the photovoltaic driving unit comprises a photovoltaic power generation module, an execution module and a denitrification reaction module, the denitrification reaction module monitors the illumination intensity and the ammonia nitrogen concentration of the sewage in the biological filter in real time, and distributes photovoltaic electric energy to the denitrification reaction module or other units needing power supply on the basis of comparison of the monitored illumination intensity and the ammonia nitrogen concentration of the sewage in the biological filter with a preset threshold, so that the energy use efficiency is optimized; the denitrification reaction module is arranged in the biological filter, controllable current is applied to accelerate denitrification of the biological filter, ammonia nitrogen is directly oxidized at an anode or indirectly oxidized through active chlorine, hydrogen is generated at a cathode to serve as a denitrification electron donor, nitrate is accelerated to be reduced into nitrogen, and the problem that a traditional denitrification carbon source is insufficient is solved.

Description

Technical Field

[0001] This invention relates to biofilter technology, and more particularly to a photovoltaic-driven integrated biofilter device and its denitrification method. Background Technology

[0002] Biological filters are used for the purification and treatment of domestic sewage. They use a microbial film attached to the surface of the filter media to biodegrade pollutants such as organic matter and ammonia nitrogen in the sewage. Traditional biological filters usually rely on the power grid to meet the power requirements for aeration and recirculation, resulting in high operating costs. Moreover, during the denitrification stage, insufficient carbon source often affects the denitrification effect, requiring the addition of additional carbon source, which increases the complexity and cost of operation.

[0003] To reduce energy consumption and improve system sustainability, existing technologies include biofilter systems that combine photovoltaic (PV) drive. For example, Chinese Patent Publication No. CN115611467A proposes a rural domestic sewage treatment device that combines PV drive with solar heating control. The PV system powers the filter and heating system, and the solar heating system maintains the water temperature in winter.

[0004] In this patent, microbial activity is maintained through heating, with heating control relying solely on a single temperature parameter. When the temperature of the insulated hot water tank falls below the set value, the electric heater activates regardless of the current wastewater load or the remaining battery power. During periods of limited sunlight, this rapidly depletes the limited battery capacity, making continuous operation impossible. Summary of the Invention

[0005] Based on the above-mentioned technical problems, this invention proposes a photovoltaic-driven integrated biological filter device and its denitrification method. The device monitors the light intensity and ammonia nitrogen concentration in wastewater in real time through the execution module, and dynamically allocates photovoltaic power to the denitrification reaction module or other power-requiring units to optimize energy use efficiency.

[0006] The technical solution of this invention is implemented as follows: A photovoltaic-driven integrated biofilter device includes a biofilter and a photovoltaic driving unit, characterized in that the photovoltaic driving unit includes: Photovoltaic power generation modules; The execution module is used to monitor the light intensity and the ammonia nitrogen concentration of the wastewater in the biological filter in real time, and to allocate the electrical energy generated by the photovoltaic power generation module based on the comparison between the monitored light intensity and the ammonia nitrogen concentration of the wastewater in the biological filter and a preset threshold. A denitrification reaction module is installed inside the biofilter, and a controllable current is applied to accelerate the denitrification of the biofilter.

[0007] Preferably, the execution module determines the intensity of light L(t) and the ammonia nitrogen concentration C(t) of the wastewater in the biological filter based on the monitored light intensity threshold L. set and ammonia nitrogen concentration threshold C set The comparison, When L(t) > L set And C(t) > C set At that time, electrical energy is preferentially allocated to the denitrification reaction module, and a high current density is applied; When L(t) > L set And C(t) <C set At that time, electrical energy is distributed to the denitrification reaction module, a low current density is applied, and excess electrical energy is used to charge the storage battery; When L(t) <L set And C(t) > C set At that time, electrical energy is distributed to the denitrification reaction module in conjunction with the discharge of the storage battery, and an adjusted current density is applied; When L(t) <L set And C(t) <C set At that time, only the minimum external power supply is maintained.

[0008] Preferably, the adjusted current density The calculation formula is as follows: ;

[0009] in, This represents the adjusted current density at time i; Indicates high current density; This represents the total output power of the photovoltaic panel at time i; Indicates the proportional control coefficient; This represents the state of charge of the storage battery at time i; This indicates the target charge setting value for the storage battery; This indicates the rated power of the denitrification reaction module.

[0010] Preferably, the proportional control coefficient Specifically: ;

[0011] in, Indicates the baseline value; as well as Indicates the weighting coefficient; This indicates the rate of change of charge in a storage battery; This indicates the fluctuation rate of the photovoltaic panel's output power.

[0012] Preferably, the filter tank includes a filter bed, filter media, water distribution nozzles, and an air distributor, wherein the filter media is ceramsite, activated carbon, quartz sand, or plastic balls, for microbial attachment and growth.

[0013] Preferably, the denitrification reaction module is installed on the side close to the gas distributor, and the denitrification reaction module is provided with one or more pairs of electrodes.

[0014] Preferably, the denitrification reaction module directly oxidizes ammonia nitrogen at the anode or indirectly oxidizes ammonia nitrogen through active chlorine, and generates hydrogen or hydrogen peroxide at the cathode. In this case, hydrogen acts as an electron donor for denitrifying microorganisms, accelerating the reduction of nitrate to nitrogen.

[0015] Preferably, the photovoltaic power generation module includes multiple photovoltaic panels and a DC / DC converter for supplying power to the filtration tank, aeration tank, equalization tank, backwashing tank, and denitrification reaction module.

[0016] Preferably, the execution module determines the total output power P of the multiple photovoltaic panels. pv (t) Perform power distribution, the total output power P of the multiple photovoltaic panels pv The formula for calculating (t) is as follows: ;

[0017] In the formula, A represents the total area of ​​multiple photovoltaic panels; L(t) represents the overall efficiency of the photovoltaic panel; L(t) represents the solar irradiance at time t; k represents the power temperature coefficient; T1(t) represents the temperature of the photovoltaic panel at time t; and T0 represents the reference temperature of the photovoltaic panel under standard test conditions.

[0018] A nitrogen removal method for a photovoltaic-driven integrated biological filter, characterized by comprising the following steps: Step 1: Start the photovoltaic power generation module, execution module and denitrification reaction module, and initialize the parameters of each module; Step 2: Use a light sensor to monitor the light intensity L(t) in real time, use an ammonia nitrogen sensor to monitor the ammonia nitrogen concentration C(t) in the wastewater in the biological filter in real time, and monitor the total output power P of the photovoltaic panel. pv (t) and the state of charge (SOC(t) of the storage battery; Step 3: The denitrification reaction module applies a controllable current to the biological filter to accelerate denitrification through electrochemical action; Step 4: The execution module switches between any of the following modes: S1, S2, S3, and S4, based on the comparison between real-time data and preset thresholds. Step 5: Dynamically adjust the current density. In S3 mode, calculate the adjusted current density.

[0019] The photovoltaic-driven integrated biological filter equipment and its nitrogen removal method of this invention have the following beneficial effects: 1. Direct power supply via photovoltaic power generation modules reduces reliance on the traditional power grid, lowering energy consumption and operating costs. The execution module monitors real-time sunlight intensity and wastewater ammonia nitrogen concentration, dynamically allocating photovoltaic power to the denitrification reaction module or other power-requiring units, optimizing energy efficiency. It also charges the storage battery when sunlight is sufficient, enabling energy storage and reuse.

[0020] 2. The denitrification reaction module applies a controllable current to directly oxidize ammonia nitrogen at the anode or indirectly through active chlorine, generating hydrogen gas at the cathode as an electron donor for denitrification, accelerating the reduction of nitrate to nitrogen gas and solving the problem of insufficient carbon source in traditional denitrification. Based on light intensity and ammonia nitrogen concentration thresholds, it dynamically and automatically switches between S1-S4 operating modes to ensure efficient denitrification under different conditions.

[0021] 3. In S3 mode, the current density is adjusted through an algorithm to avoid electrode impact and prevent over-discharge of the battery. The proportional control coefficient is dynamically adjusted based on the battery's state of charge and photovoltaic power fluctuations, enhancing the system's adaptability to uncertain environments and ensuring the continuity and reliability of the denitrification process. Attached Figure Description

[0022] Figure 1 This is a process flow diagram of the biological filter equipment of the present invention; Figure 2 This is a schematic diagram of the structure of the biological filter of the present invention; Figure 3 This is a schematic diagram of the structure of the photovoltaic driving unit of the present invention; Figure 4 This is another structural schematic diagram of the photovoltaic drive unit of the present invention; Figure 5 This is a logic block diagram of the photovoltaic driving unit of the present invention; Figure 6 This is a flowchart of the execution module of the present invention in S3 mode; Figure 7 This is a flowchart of the nitrogen removal method of the biological filter equipment of the present invention.

[0023] The reference numerals in the attached figures are: 100 photovoltaic drive unit, 101 photovoltaic power generation module, 102 execution module, 103 denitrification reaction module, 200 biological filter, 201 filter bed, 202 filter media, 203 water distribution nozzle, and 204 air distributor. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0025] Domestic sewage contains a large amount of organic matter (such as COD and BOD), nitrogen and phosphorus nutrients, and suspended solids. If it is discharged directly without treatment, it will easily cause eutrophication of water bodies.

[0026] Reference Figure 1 As shown, domestic sewage first enters the filtration tank, where large particulate impurities such as suspended solids, sand, and floating matter are removed through physical interception. After preliminary filtration, the sewage enters the aeration tank for aerobic treatment under aeration. The effluent from the aeration tank enters the equalization tank to adjust the pH of the sewage and balance the water quality. The water from the equalization tank then flows into the backwash tank to wash away suspended solids, biofilm, and other impurities that gradually accumulate on the filter media surface. The effluent from the backwash tank enters the biological filter, where a biofilm forms on the filter media surface. Microorganisms on the biofilm further degrade pollutants such as organic matter and ammonia nitrogen, achieving deep purification.

[0027] The filter media from the biological filter is then returned to the backwashing tank for regular backwashing to remove accumulated dirt and biofilm, maintaining the filtration efficiency and permeability of the biological filter.

[0028] The effluent from the biological filter enters the sludge filtration stage to remove residual suspended solids and some biological flocs. After filtration, it meets the reuse standards and can be reused.

[0029] Example 1

[0030] Reference Figures 2 to 6 As shown, the first embodiment of the present invention proposes a photovoltaic-driven integrated biological filter device including a photovoltaic drive unit 100, which is used to control or drive a filter tank, an aeration tank, an equalization tank, a backwashing tank, and a biological filter. The photovoltaic drive unit 100 includes a photovoltaic power generation module 101, an execution module 102, and a denitrification reaction module 103. The denitrification reaction module 103 is installed inside the biological filter.

[0031] In this embodiment, the biofilter 200 includes a filter bed 201 filled with granular filter media 202, such as ceramsite, activated carbon, quartz sand, or plastic balls. The filter media 202 provides a biological carrier and living space for microbial growth. A viscous biofilm, composed of a microbial community and its secreted extracellular polymers, adheres to the filter media 202. This biofilm serves as the biochemical reaction site for the biofilter 200.

[0032] The microbial community can be bacteria, fungi, protozoa, etc.

[0033] A water distribution nozzle 203 is provided at the top of the filter bed 201, which evenly distributes the wastewater to be treated on the surface of the filter bed 201. An air distributor 204 is provided at the bottom of the filter bed 201, which supplies air to the filter bed 201 for microbial respiration.

[0034] Specifically, the biofilter 200 mainly relies on nitrification, where biodegradation is completed by specific microorganisms under aerobic conditions.

[0035] Wastewater flows into filter bed 201 through water distribution nozzle 20, and then flows downward through filter media 202 under gravity. Pollutants in the wastewater, generally ammonia nitrogen and organic pollutants, diffuse from the flowing aqueous phase onto the biofilm attached to the surface of the filter media. After entering the biofilm, the pollutants are decomposed by the microorganisms within it.

[0036] When wastewater passes through filter media 202, the filter media 202 and the biofilm attached to it form a dense filter layer that can trap and remove suspended solids and colloidal substances in the wastewater.

[0037] Furthermore, ammonia nitrogen in wastewater is converted into nitrate through nitrification, which occurs in two stages: In the nitrosation stage, ammonia nitrogen is oxidized to nitrite. The chemical formula is: Energy; at this stage, a large amount of oxygen is consumed and hydrogen ions are produced, leading to a decrease in local pH.

[0038] During the nitration stage, nitrite is further oxidized to nitrate. The chemical formula is: energy.

[0039] Overall nitration reaction: Through nitrification, harmful ammonia nitrogen in the water is converted into nitrate nitrogen. It should be noted that for complete nitrogen removal, denitrification is required subsequently.

[0040] Furthermore, denitrification converts nitrates into nitrogen gas. Under anaerobic conditions, nitrates are gradually reduced back to nitrogen gas, with the chemical formula being: .

[0041] Overall denitrification reaction: The final product, N2, is a harmless gas that will escape from the water or be collected in canisters, thus achieving complete nitrogen removal.

[0042] In this embodiment, the photovoltaic power generation module 101 consists of multiple photovoltaic panels and a DC / DC converter. The multiple photovoltaic panels directly supply power to the filter tank, aeration tank, equalization tank, and backwashing tank, as well as drive the denitrification reaction module 103.

[0043] Among them, the execution module 102 determines the total output power P of the multiple photovoltaic panels. pv (t) Distribute electrical energy. The total output power P of multiple photovoltaic panels. pv The formula for calculating (t) is as follows: ;

[0044] In the formula, A represents the total area of ​​multiple photovoltaic panels; The overall efficiency of the photovoltaic panel reflects its efficiency in converting solar energy into electrical energy, typically ranging from 0.15 to 0.22; L(t) represents the solar irradiance at time t, measured by a light sensor; k represents the power temperature coefficient, indicating the relative decrease in output power for every 1°C increase in temperature, generally ranging from 0.4% to 0.5%; T1(t) represents the photovoltaic panel temperature at time t; and T0 represents the reference temperature of the photovoltaic panel under standard test conditions, typically 25°C.

[0045] The output power of a photovoltaic panel is directly proportional to its area, efficiency, and light intensity, but it is affected by temperature. That is, when the current temperature T1(t) of the photovoltaic panel is greater than the reference temperature T0, the output power will decrease; conversely, if the current temperature T1(t) of the photovoltaic panel is less than the reference temperature T0, the output power will increase.

[0046] In this embodiment, the power of the photovoltaic panel directly affects the amount of electrical energy it converts. The execution module 102 distributes the electrical energy converted by the photovoltaic panel. (Refer to...) Figure 3 and Figure 5 As shown, a light sensor measures the solar irradiance of the photovoltaic panel at time t, and an ammonia nitrogen sensor measures the ammonia nitrogen content of the wastewater in the biological filter 200. Based on the comparison between the real-time monitored light intensity L(t) and the ammonia nitrogen concentration C(t) in the wastewater of the biological filter and a preset threshold, the system adjusts to a predetermined operating mode to balance photovoltaic power and denitrification efficiency.

[0047] The execution module 102 defines the following states: When the current light intensity L(t) is greater than the light intensity threshold L set Furthermore, the current ammonia nitrogen concentration C(t) in the wastewater is greater than the ammonia nitrogen concentration threshold C. set When the execution module 102 ensures a stable external power supply, it distributes the electrical energy generated by the photovoltaic panel to the denitrification reaction module 103. The denitrification reaction module 103 applies a high current density to prioritize rapid denitrification, which is the S1 mode.

[0048] When the current light intensity L(t) is greater than the light intensity threshold L set And the current ammonia nitrogen concentration C(t) in the wastewater is less than the ammonia nitrogen concentration threshold C. set When the execution module 102 ensures a stable external power supply, it distributes the electrical energy generated by the photovoltaic panel to the denitrification reaction module 103. The denitrification reaction module 103 applies a low current density and charges the storage battery with the excess electrical energy, which is the S2 mode.

[0049] When the current light intensity L(t) is less than the light intensity threshold Lset Furthermore, the current ammonia nitrogen concentration C(t) in the wastewater is greater than the ammonia nitrogen concentration threshold C. set When the execution module 102 ensures stable external power supply, it distributes the electrical energy generated by the photovoltaic panel and the discharge of the storage battery to the denitrification reaction module 103. The denitrification reaction module 103 applies an adjusted current density, which is in S3 mode.

[0050] In S3 mode, the execution module 102 calls the intelligent algorithm to smoothly reduce and apply an optimized adjustment current density based on the battery discharge, so as to ensure continuous and efficient denitrification under limited power and prevent battery over-discharge.

[0051] When the current light intensity L(t) is less than the light intensity threshold L set And the current ammonia nitrogen concentration C(t) in the wastewater is less than the ammonia nitrogen concentration threshold C. set At this time, the power generated by the photovoltaic panels or the power stored in the batteries is used to maintain the external power supply, which is the S4 mode.

[0052] In S4 mode, only a minimal external power supply is maintained, relying mainly on the traditional biochemical functions of the biofilter itself, so that the entire equipment enters a low-power operation state.

[0053] In this embodiment, the denitrification reaction module 103 is installed near the gas distributor 204 to ensure aerobic conditions in a portion of the area, while simultaneously creating an anoxic / anaerobic microenvironment, and is equipped with one or more pairs of electrodes. By applying a controllable current to the denitrification reaction module 103, the denitrification process is accelerated.

[0054] Specifically, when the execution module 102 drives the denitrification reaction module 103, a current density J is applied to the electrode according to the current S1 to S4 modes.

[0055] At the anode surface, ammonia nitrogen in wastewater can be directly oxidized, while the active chlorine generated electrochemically indirectly oxidizes the ammonia nitrogen. The chemical formula is: .

[0056] On the cathode surface, a reduction reaction occurs to produce hydrogen gas (H2) or hydrogen peroxide (H2O2). Hydrogen gas serves as an excellent electron donor for denitrifying microorganisms, significantly increasing their reduction of nitrate (NO3). - The rate of reduction to nitrogen (N2) compensates for the limitation of insufficient carbon source in traditional denitrification.

[0057] At the same time, the applied electric field can also change the permeability of microbial cells and activate the activity of key enzymes, thereby improving the overall metabolic rate of microorganisms.

[0058] Furthermore, referring to Figure 6As shown, a common application scenario is when the ammonia nitrogen concentration C(t) in wastewater is greater than the ammonia nitrogen concentration threshold C. set At this time, the solar panel's illumination is affected by weather or external factors, and the illumination suddenly weakens, switching from S1 mode to S3 mode. It is necessary to smoothly reduce the current density of the denitrification reaction module 103 to avoid impacting the electrodes and to redistribute electrical energy. The current density of the denitrification reaction module 103 is adjusted using the following algorithm: ;

[0059] In the formula, at time i, the illumination suddenly decreases, switching from mode S1 to mode S3. This represents the adjusted current density at time i; Indicates high current density; This represents the total output power of the photovoltaic panel at time i; Indicates the proportional control coefficient; This represents the state of charge of the storage battery at time i; This indicates the target charge setting value for the storage battery, typically 50%. This indicates the rated power of the denitrification reaction module 103.

[0060] When the battery charge state of the storage battery at time i Significantly deviates from the target charge setting value of the storage battery When this absolute value increases, it leads to Increase. Increase It amplifies the impact of charge deviation on current density, thereby adjusting the current density to prevent over-discharge of the battery.

[0061] In this embodiment, the proportional control coefficient This is not a fixed value; when the state of charge of the storage battery decreases or the total output power of the photovoltaic panel decreases, the uncertainty of power generation prediction increases. The current density applied to the denitrification reaction module 103 is adjusted by increasing the current density to prevent over-discharge of the battery.

[0062] Among them, the rate of change of charge through the storage battery and the fluctuation rate of photovoltaic panel output power Therefore, the proportional control coefficient is adjusted. . Specifically: ;

[0063] In the formula, Indicates the baseline value. as well as This represents the weighting coefficient, obtained through pre-setting or online calibration. Among them, the rate of charge change of the storage battery... and the fluctuation rate of photovoltaic panel output power A sharp decline also led to The current density is increased to compensate for the reduced output power of the photovoltaic panels and insufficient power generation.

[0064] It should be noted that the high current density is 30-40 mA / cm², and the low current density is 5-15 mA / cm². In S3 mode, the denitrification reaction module 103 applies an adjusted current density of 15-30 mA / cm².

[0065] Example 2 Based on the above embodiments, referring to Figure 7 As shown, another embodiment of the present invention proposes a photovoltaic-driven integrated biological filter denitrification method, comprising the following steps: Step 1: Start the photovoltaic power generation module, execution module and denitrification reaction module, and initialize the parameters of each module; The parameters for each module include the light intensity threshold L. set ammonia nitrogen concentration threshold C set Target State of Charge (SOC) of a Storage Battery mid The rated power P of the denitrification reaction module ra Proportional control coefficient K p Weighting coefficient α, weighting coefficient β, and current density reference value, Among them, the current density reference value includes high current density J high Low current density J low And adjusting the current density J s .

[0066] Step 2: Use a light sensor to monitor the light intensity L(t) in real time. The ammonia nitrogen concentration C(t) in the wastewater of the biological filter was monitored in real time using an ammonia nitrogen sensor. Monitoring the total output power P of the photovoltaic panel pv (t) and the state of charge (SOC(t) of the storage battery.

[0067] Step 3: The denitrification reaction module applies a controllable current to the biological filter to accelerate denitrification through electrochemical action. The anode reaction directly oxidizes ammonia nitrogen or indirectly oxidizes it through active chlorine, while the cathode reaction generates hydrogen or hydrogen peroxide, which provides electron donors for denitrifying microorganisms and promotes the reduction of nitrate to nitrogen.

[0068] Step 4: The execution module switches between S1, S2, S3, and S4 modes based on the comparison between real-time data and preset thresholds. When L(t) > L set And C(t) > C setAfter switching to S1 mode and ensuring a stable external power supply, photovoltaic power is preferentially allocated to the denitrification reaction module, and a high current density J is applied. high Rapid denitrification; When L(t) > L set And C(t) < C set， After switching to S2 mode and ensuring a stable external power supply, the photovoltaic power is distributed to the denitrification reaction module, and a low current density J is applied. low And it will use the excess electrical energy to charge the storage battery; When L(t) < L set And C(t) > C set Switch to S3 mode. After ensuring a stable power supply to the external environment, the power is distributed to the denitrification reaction module in conjunction with the discharge of the storage battery, and the adjusted current density Js is applied. When L(t) < L set And C(t) < C set When switched to S4 mode, it maintains only a minimum external power supply and relies on the traditional biochemical functions of the biofilter to enter a low-power operation state.

[0069] Step 5: Dynamically adjust the current density. In S3 mode, calculate the adjusted current density.

[0070] In this embodiment, photovoltaic power is dynamically allocated and the denitrification process is optimized by real-time detection of light intensity and ammonia nitrogen concentration in wastewater.

[0071] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A photovoltaic-driven integrated biofilter apparatus comprising a biofilter and a photovoltaic driving unit, characterized by, The photovoltaic driving unit comprises: a photovoltaic power generation module; an execution module for monitoring the light intensity and the ammonia nitrogen concentration of sewage in the biological filter in real time, and distributing the electric energy generated by the photovoltaic power generation module based on the comparison of the light intensity, the ammonia nitrogen concentration of sewage in the biological filter and the preset threshold value obtained by the monitoring; a denitrification reaction module arranged in the biological filter, which applies a controllable current to accelerate the denitrification of the biological filter.

2. The photovoltaic-driven integrated biofilter apparatus according to claim 1, wherein The execution module compares the monitored light intensity L(t), the ammonia nitrogen concentration C(t) of the sewage in the biofilter with the light intensity threshold L set and the ammonia nitrogen concentration threshold C set , When L(t) > L set and C(t) > C set , the electrical energy is preferentially allocated to the denitrification reaction module, and a high current density is applied. When L(t) > L set and C(t) < C set , the electrical energy is distributed to the denitrification reaction module, and a low current density is applied, and the surplus electrical energy charges the storage battery; When L(t) < L set and C(t) > C set , the electrical energy is distributed to the denitrification reaction module in combination with the discharge of the storage battery, and an adjusted current density is applied. When L(t) < L set and C(t) < C set , only minimal external power is maintained.

3. The photovoltaic-driven integrated biofilter apparatus according to claim 2, wherein the adjusted current density The calculation formula is as follows: ； wherein, represents the current density adjusted at the instant i; represents a high current density; represents the total output power of the photovoltaic panel at the instant i; represents a proportional control coefficient; represents the state of charge of the storage battery at the instant i; represents the target charge set value of the storage battery; represents the rated power of the denitrification reaction module.

4. The photovoltaic-driven integrated biofilter apparatus according to claim 3, wherein The proportional control coefficient Specifically: ； wherein, represents a reference value; and represents a weight coefficient; represents a charge change rate of the storage battery; represents a photovoltaic panel output power fluctuation rate.

5. The photovoltaic-driven integrated biofilter apparatus according to claim 1, wherein The biological filter comprises a filter bed, filter material, water distribution nozzle and air distributor, wherein the filter material is ceramic, activated carbon, quartz sand or plastic ball for microbial attachment and growth.

6. The photovoltaic-driven integrated biofilter apparatus according to claim 5, wherein The denitrification reaction module is installed on one side close to the air distributor, and the denitrification reaction module is provided with one or more pairs of electrodes.

7. The integrated biotrickling filter device driven by photovoltaic power according to claim 6, characterized in that, The denitrification reaction module directly oxidizes ammonia nitrogen at the anode or indirectly oxidizes ammonia nitrogen through active chlorine, and generates hydrogen gas or hydrogen peroxide at the cathode, wherein the hydrogen gas serves as an electron donor for denitrifying microorganisms to accelerate the reduction of nitrate to nitrogen.

8. The integrated biotrickling filter device driven by photovoltaic power according to claim 1, characterized in that, The photovoltaic power generation module comprises a plurality of photovoltaic panels and a DC / DC converter for supplying power to the filter tank, the aeration tank, the adjustment tank, the backwashing tank and the denitrification reaction module.

9. The photovoltaic-driven integrated biofilter apparatus according to claim 8, wherein The execution module calculates the total output power P pv (t) of the plurality of photovoltaic panels based on the output power P pv (t) of each photovoltaic panel and the number of photovoltaic panels N pv (t) is calculated as follows: ； wherein A represents the total area of the plurality of photovoltaic panels; represents the overall efficiency of the photovoltaic panel; L(t) represents the solar irradiance at time t; k represents the power temperature coefficient; T1(t) represents the photovoltaic panel temperature at time t; and T0 represents the reference temperature of the photovoltaic panel under standard test conditions.

10. A method for denitrification of a photovoltaic-driven integrated biological filter apparatus comprising the photovoltaic-driven integrated biological filter apparatus according to claim 1, characterized by, The method comprises the following steps: Step 1: start the photovoltaic power generation module, the execution module and the denitrification reaction module, and initialize the parameters of each module; Step2: Real-time monitoring of light intensity L(t) using light sensor, real-time monitoring of ammonia nitrogen concentration C(t) in the biological filter using ammonia nitrogen sensor, monitoring the total output power P of photovoltaic panel pv (t) and the state of charge SOC(t) of the storage battery; Step 3: the denitrification reaction module applies a controllable current in the biological filter to accelerate denitrification through electrochemical action; Step 4: the execution module switches any one of S1 mode, S2 mode, S3 mode and S4 mode according to the comparison of real-time data and preset threshold value; Step 5: dynamically adjust the current density, and calculate the adjusted current density in S3 mode.

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