Application method of phycomycete synergy in livestock and poultry breeding wastewater treatment

Abstract

The invention provides an application method of phycomycete synergy in livestock and poultry breeding wastewater treatment, which comprises the following steps: S1, strengthening pretreatment: sequentially carrying out solid-liquid separation, demulsification and oil removal and water quality balance adjustment on livestock and poultry breeding wastewater; grease and refractory pollutants are removed through enhanced pretreatment, and a clean environment is created for metabolism of phycomycetes; the modified carrier and the composite flora improve the stability and the synergistic effect of the system; the photovoltaic system is matched with intelligent regulation and control and accurately adapts to the growth requirements of phycomycetes, so that efficient utilization of clean energy is realized, the influence caused by fluctuation of factors such as illumination and temperature is avoided, the wastewater treatment process is always kept in an efficient metabolic state, external energy consumption input is greatly reduced, and breakthrough optimization of a technical route is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wastewater treatment, in particular to an application method of algal-bacterial cooperation in treating livestock and poultry breeding wastewater. BACKGROUND

[0002] Livestock and poultry breeding wastewater is one of the main sources of agricultural non-point source pollution, which has the characteristics of high COD, high ammonia nitrogen, high phosphorus, and contains oil, suspended solids, and is complex in composition and high in pollutant concentration. If it is directly discharged, it will seriously pollute water bodies, soil and air, and threaten the ecological environment and public health, so efficient treatment of such wastewater has become an important issue in environmental governance. The current mainstream treatment technologies include physical and chemical methods and biological methods. The physical and chemical methods have the problems of high cost and easy secondary pollution, and the biological methods are the first choice due to environmental protection and economy. Algal-bacterial cooperation technology takes advantage of the mutualistic symbiotic relationship between microalgae and bacteria to degrade pollutants while realizing resource conversion, and is considered as a very promising treatment direction, which has gradually attracted attention and application in the treatment of livestock and poultry breeding wastewater in recent years.

[0003] The existing algal-bacterial cooperation treatment technology still has many limitations to be solved in practical application. The pretreatment link is relatively simple, and most of them only focus on solid-liquid separation, without targeted treatment of oil and refractory organic matter contained in the wastewater, which leads to the inhibition of the activity of the subsequent algal-bacterial system and may cause equipment blockage. The algal-bacterial system itself has deficiencies, most of which are single functional flora, the performance of the immobilized carrier is ordinary, and the bacteria and algae are easy to lose, and the denitrification and phosphorus removal synergistic effect is not good. At the same time, the technology is heavily dependent on natural light, and there is a lack of precise control means for key parameters such as temperature and dissolved oxygen, and the treatment effect is greatly affected by day and night and seasons, and the stability is poor, while artificial light supplement and aeration will lead to high energy consumption. In addition, the algal-bacterial biomass recovery is difficult, the resourceization path is single, and only limited to simple utilization, which cannot realize the value maximization, and is difficult to adapt to the diversified needs of practical application. SUMMARY

[0004] (I) Technical problems solved In view of the deficiencies of the prior art, the present application provides an application method of algal-bacterial cooperation in treating livestock and poultry breeding wastewater, which solves the problems of the existing algal-bacterial cooperation treatment technology that the pretreatment link is relatively simple, the technology is heavily dependent on natural light, there is a lack of precise control means for key parameters such as temperature and dissolved oxygen, and the algal-bacterial biomass recovery is difficult, and the resourceization path is single.

[0005] (II) Technical scheme In order to achieve the above purpose, the present application is implemented by the following technical scheme: an application method of algal-bacterial cooperation in treating livestock and poultry breeding wastewater, comprising the following steps: S1: strengthening the pretreatment step, sequentially performing solid-liquid separation, demulsification and oil removal, and water quality balance adjustment on the livestock and poultry breeding wastewater; S2: algae and bacteria synergistic treatment step, the pretreated wastewater is introduced into the reactor and contacted with the modified immobilized algae and bacteria symbiotic system to efficiently remove organic matter, nitrogen and phosphorus in the wastewater; During the contact reaction, the following intelligent closed-loop control sub-steps are performed: S21: using a solar photovoltaic power generation system equipped with a maximum power point tracking controller to provide stable operating power for the reactor and supporting equipment; S22: using an LED light source with adjustable light quality, light intensity and light duration to provide precise artificial light for the algae and bacteria symbiotic system in the reactor; S23: real-time monitoring of water quality parameters in the reactor, including ammonia nitrogen concentration, total phosphorus concentration, COD, dissolved oxygen and pH value; S24: based on the water quality parameters monitored in S23, dynamically adjusting the light parameters of the LED light source, the stirring rate of the reactor, the start-stop and intensity of the auxiliary aeration, and the temperature in the reactor.

[0006] Preferably, in S24, the dynamic adjustment of the light parameters of the LED light source specifically includes: adjusting the output intensity ratio of red light to blue light in the LED light source according to the monitored ammonia nitrogen concentration; when the ammonia nitrogen concentration is higher than the first set threshold, increasing the output intensity of the blue light component to strengthen the nitrification of algae.

[0007] Preferably, in S24, the dynamic adjustment of the start-stop of the auxiliary aeration specifically includes: starting the micro-bubble aeration device for auxiliary oxygen supply when the monitored dissolved oxygen concentration is lower than the second set threshold; stopping aeration when the dissolved oxygen concentration returns to the third set threshold.

[0008] Preferably, the immobilized algae and bacteria symbiotic system is algae and bacteria gel particles embedded with chlorella and nitrifying bacteria, or a three-dimensional elastic filler with algae and bacteria biofilm attached.

[0009] Preferably, during the contact reaction, a temperature control sub-step is also included: using photovoltaic power to drive heating or cooling devices to maintain the temperature in the reactor within a constant range of 20-30℃.

[0010] Preferably, after the algae and bacteria synergistic treatment step, the following steps are also included: S3: solid-liquid separation step to separate the treated water from the algae and bacteria biomass; S4: resource step, the separated algae and bacteria biomass is subjected to anaerobic fermentation to produce biogas, or is dried and processed into biofertilizer.

[0011] (Three) beneficial effects The application provides an application method of algal-bacterial cooperation in treating livestock and poultry breeding wastewater. 1、The application creates a clean environment for algal-bacterial metabolism by strengthening pretreatment to remove grease and refractory pollutants; the modified carrier and the complex bacterial population improve the system stability and synergistic efficiency; the photovoltaic system is matched with intelligent regulation and control to accurately adapt to the growth requirements of algal bacteria, which not only realizes efficient use of clean energy, but also avoids the influence of factors such as light and temperature fluctuations, keeps the wastewater treatment process in a high-efficiency metabolic state at all times, and greatly reduces external energy consumption input, achieving a breakthrough optimization of the technical route.

[0012] 2、The application realizes efficient recovery of algal-bacterial biomass through hierarchical solid-liquid separation, and combines multiple resource utilization paths to convert by-products into valuable products such as biogas, organic fertilizer or microalgae oil, etc., so that the treatment process extends from simple environmental governance to resource recycling, taking into account environmental and economic benefits. DETAILED DESCRIPTION

[0013] The technical solutions in the embodiments of the application will be described below in a clear and complete manner. Obviously, the described embodiments are only a part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the application.

[0014] Embodiment: The embodiment of the application provides an application method of algal-bacterial cooperation in treating livestock and poultry breeding wastewater, which comprises the following steps: S1: strengthening pretreatment step, sequentially performing solid-liquid separation, demulsification and oil removal, and water quality balance adjustment on livestock and poultry breeding wastewater; (1) solid-liquid separation: a mechanical grid with a pore size of 1-3 mm is used to continuously intercept and treat the livestock and poultry breeding wastewater, so as to remove fecal residues, feed debris and other large particle suspended solids, the grid overflow velocity is controlled at 0.8-1.2 m / s, the surface of the grid is rinsed at regular intervals every day to avoid blockage.

[0015] (2) demulsification and oil removal: the grid effluent is introduced into a demulsification tank, 80-150 mg / L of polyaluminum chloride or aluminum sulfate is added as a demulsifier according to the oil content (measured range 20-100 mg / L) of the wastewater, the stirring rate is 30-50 r / min, the stirring time is 10-15 minutes, and after standing for 20-30 minutes, the upper floating oil is collected by an oil skimmer, and the lower water enters the adjustment tank.

[0016] (3) Water quality balance regulation: The effective volume of the regulation tank is designed according to 1 / 3-1 / 2 of the daily discharge of wastewater, the residence time is 6-12 hours, a submersible mixer (power 0.5-1.5 kW) is arranged in the tank to keep the water uniformly mixed, so that the COD fluctuation range of the effluent is ≤±10%, the ammonia nitrogen fluctuation range is ≤±8%, and stable influent conditions are provided for the subsequent algal-bacterial treatment.

[0017] S2: Algal-bacterial synergistic treatment step, the pretreated wastewater is introduced into the reactor and contacted with the modified immobilized algal-bacterial symbiotic system to efficiently remove organic matter, nitrogen and phosphorus in the wastewater; (1) Reactor and algal-bacterial system: The reactor is made of cylindrical organic glass or stainless steel, with an effective volume of 5-50 m³ and a height-diameter ratio of 1.2-1.5. The modified immobilized algal-bacterial symbiotic system is added at 5%-10% of the wastewater volume, and the surface impurities are washed with physiological saline before adding to ensure the activity of bacteria and algae.

[0018] (2) Photovoltaic power generation system operation (S21): Single-crystal silicon solar photovoltaic panels are laid on the top of the reactor, and the total power is matched according to the equipment energy consumption (500-5000 W), with an MPPT controller and a battery pack (capacity 100-1000 Ah). The MPPT controller real-time tracks the maximum power output point of the photovoltaic panel, and the power conversion efficiency is improved to 18%-22%, and the battery pack ensures the continuous operation of the equipment at night or in rainy days, and the power supply stability is ≥95%.

[0019] (3) LED lighting system setting (S22): LED light panels are evenly arranged on the inner wall or top of the reactor, with a spacing of 30-50 cm, red light (660 nm) and blue light (450 nm) are the core light quality, the initial light intensity is controlled at 50-100 μmol / (m²・s), the light illumination time is 12 h / d by default, the light panel protection level is ≥IP65, and it is suitable for humid environment.

[0020] (4) Multi-parameter monitoring implementation (S23): One set of multi-parameter sensors is installed at three positions on the reactor, including ammonia nitrogen (detection range 0-100 mg / L, accuracy ±0.1 mg / L), total phosphorus (0-50 mg / L, accuracy ±0.05 mg / L), COD (0-5000 mg / L, accuracy ±5%), dissolved oxygen (0-20 mg / L, accuracy ±0.1 mg / L), and pH value (0-14, accuracy ±0.05), the data acquisition frequency is 5 minutes / minute, and the data is transmitted to the intelligent control system in real time.

[0021] (5) Intelligent control starting logic (S24): After receiving the sensor data, the control system triggers the control command according to the preset threshold, the control response delay is ≤10 minutes, all control parameters are automatically recorded and archived for subsequent optimization and adjustment.

[0022] In the process of the contact reaction, the following intelligent closed-loop regulation sub-steps are performed: S21: A solar photovoltaic power generation system equipped with a maximum power point tracking controller is used to provide stable operating power for the reactor and the supporting equipment; S22: An LED light source with adjustable light quality, light intensity, and light duration is used to provide precise artificial light for the algae-bacteria symbiotic system in the reactor; S23: Real-time monitoring of water quality parameters in the reactor, including ammonia nitrogen concentration, total phosphorus concentration, COD, dissolved oxygen, and pH value; S24: Based on the water quality parameters monitored in S23, dynamically regulating the light parameters of the LED light source, the stirring rate of the reactor, the start-stop and intensity of the auxiliary aeration, and the temperature in the reactor.

[0023] In S24, the dynamic regulation of the light parameters of the LED light source specifically includes: adjusting the output intensity ratio of red light to blue light in the LED light source according to the monitored ammonia nitrogen concentration; when the ammonia nitrogen concentration is higher than the first set threshold, increasing the output intensity of the blue light component to strengthen the nitrification of algae; (1) Light quality ratio adjustment: the first ammonia nitrogen set threshold is preset to 50 mg / L, when the monitoring value is > 50 mg / L, the control system sends instructions to the LED drive module, the red light and blue light intensity ratio is adjusted from the initial 7:1 to 5:1, the blue light intensity is increased to 60-80 μmol / (m²·s), the activity of algal nitrification enzyme is strengthened; when the ammonia nitrogen concentration is ≤20 mg / L, the initial light quality ratio is restored.

[0024] (2) Light duration adjustment: the first COD set threshold is preset to 1500 mg / L, and the second set threshold is 800 mg / L. When COD > 1500 mg / L, the light duration is extended to 16 h / d, the oxygen production is increased by increasing the time of algal photosynthesis to meet the needs of bacterial degradation of high-concentration organic matter; when COD ≤800 mg / L, the light duration is restored to 12 h / d to avoid energy waste.

[0025] (3) Light intensity auxiliary adjustment: when the total phosphorus concentration is > 10 mg / L, the red light intensity is increased to 80-100 μmol / (m²·s) at the same time to enhance the assimilation and absorption capacity of algae to phosphorus; when the total phosphorus is ≤3 mg / L, the light intensity is restored to the initial level.

[0026] In S24, the dynamic regulation of the start-stop of the auxiliary aeration specifically includes: when the monitored dissolved oxygen concentration is lower than the second set threshold, starting the micro-bubble aeration device for auxiliary oxygen supply; when the dissolved oxygen concentration recovers to the third set threshold, stopping the aeration; (1) Aeration device configuration: the micro-bubble aeration heads are uniformly arranged at the bottom of the reactor, with a pore diameter of 5-10 μm, and the aeration pipeline is made of UPVC material with strong corrosion resistance.

[0027] (2) Aeration intensity grading setting: the first-stage aeration intensity is 0.5-0.8 m³ / (m²·h), and the second-stage aeration intensity is 1.0-1.2 m³ / (m²·h).

[0028] (3) Control logic: the preset second setting threshold of dissolved oxygen is 2.0 mg / L, the third setting threshold is 1.0 mg / L, and the recovery threshold is 3.0 mg / L. When the dissolved oxygen < 2.0 mg / L, the first-stage aeration is started, and intermittent operation (operation for 30 minutes and stop for 10 minutes) is adopted; when the dissolved oxygen < 1.0 mg / L, the second-stage continuous aeration is switched to; and when the dissolved oxygen ≥ 3.0 mg / L, the aeration is stopped to ensure that the dissolved oxygen is maintained in the appropriate range of 2.0-3.0 mg / L.

[0029] The immobilized algae-bacteria symbiotic system is algae-bacteria gel particles embedded with chlorella and nitrifying bacteria, or a three-dimensional elastic filler attached with algae-bacteria biofilm.

[0030] (I) Modified algae-bacteria gel particles Preparation raw materials: sodium alginate, calcium chloride, zeolite powder, chlorella, nitrifying bacteria, denitrifying bacteria, and polyphosphorus bacteria.

[0031] Preparation process: the zeolite powder is uniformly dispersed in the sodium alginate solution, the bacteria-algae mixed solution (chlorella concentration 10 6 -10 7 cells / mL, and the concentrations of the three bacteria are all 10 8 -10 9 CFU / mL, with a volume ratio of 1:1:1:1) is added, and the mixture is uniformly stirred before being dripped into the calcium chloride solution through a peristaltic pump. After being solidified for 2-4 hours, the gel particles with a diameter of 2-3 mm are formed, and then the gel particles are washed with normal saline for 2-3 times and reserved.

[0032] Application characteristics: the mechanical strength of the gel particles is ≥0.15 MPa, and the bacteria-algae immobilization rate is ≥90%. The service life can reach 3-6 months, and the expired gel particles can be directly recycled as organic fertilizer raw materials.

[0033] (II) Modified three-dimensional elastic filler Preparation raw materials: polypropylene three-dimensional elastic filler and nano titanium dioxide.

[0034] Preparation process: the three-dimensional elastic filler is soaked in the nano titanium dioxide suspension, ultrasonic treatment is performed for 30 minutes, and then the filler is taken out and dried at 60-80°C for 2 hours, so that the nano titanium dioxide is uniformly loaded on the surface of the filler to form a photocatalytic modified layer.

[0035] Application characteristics: the hydrophilicity of the modified filler is improved, the biofilm attachment rate of algae and bacteria is 20%-30% faster than that of ordinary fillers, the biofilm thickness is maintained at 0.5-1.0 mm, and the denitrification and phosphorus removal synergistic efficiency is improved by 15%-25%.

[0036] In the contact reaction process, a temperature control sub-step is also included: a photovoltaic electric energy driven heating or cooling device is used to maintain the temperature in the reactor within a constant range of 20-30°C.

[0037] (1) Temperature control device configuration: a photovoltaic driven plate heat exchanger or an electric heating tube (power 500-1000W, matched according to the reactor volume) is used, matched with a temperature sensor (detection range 0-50°C, accuracy ±0.1°C), installed in the middle of the reactor.

[0038] (2) Control logic: the preset temperature control range is 25±3°C, when the monitored temperature is <22°C, the heating device is started, and the heating power is dynamically adjusted according to the temperature deviation (the larger the deviation, the higher the power); when the temperature is >28°C, the cooling device (or cooling circulating water is introduced) is started; when the temperature is maintained at 23-27°C, the temperature control device is standby, and the control accuracy can reach ±0.5°C.

[0039] Emergency support: when the battery power is insufficient due to continuous rainy weather, the municipal power grid can be switched to auxiliary power supply (priority is given to the temperature control system operation) to avoid the influence of temperature fluctuations on the activity of algae and bacteria.

[0040] After the algae-bacteria synergistic treatment step, the following steps are also included: S3: solid-liquid separation step, separating the treated water from the algae-bacteria biomass; S4: resource utilization step, anaerobic fermentation of the separated algae-bacteria biomass to produce biogas, or drying treatment to produce biofertilizer.

[0041] (I) Graded solid-liquid separation Primary separation: inclined plate sedimentation tank is used, the inclination angle of the inclined plate is 60°, the surface load is 1.0-1.5 m³ / (m²·h), the residence time is 2-3 hours, and 80%-90% of the algae-bacteria biomass can be removed, and the turbidity of the supernatant is ≤50 NTU.

[0042] Deep separation: the supernatant after primary separation enters the ultrafiltration membrane assembly (pore size 0.1-0.2 μm, material PVDF), operating pressure 0.1-0.2 MPa, cross-flow velocity 1-2 m / s, membrane flux maintained at 50-100 L / (m²·h), periodic backwashing with clean water (1-2 times per day, 10-15 minutes each time), to remove a small amount of algae and bacteria and suspended solids intercepted on the membrane surface, and the final effluent turbidity is ≤5 NTU, meeting the livestock and poultry breeding wastewater discharge standard.

[0043] (II) Multi-resource utilization Anaerobic fermentation of biogas: Collect the algal-bacterial biomass (moisture content 60%-80%) from the bottom of the inclined plate sedimentation tank, and send it to the anaerobic fermentation tank. The fermentation temperature is controlled at 35-38℃, the residence time is 15-20 days, the gas production rate can reach 0.3-0.5m³ / kg volatile solids, and the methane content in the biogas is ≥60%. After desulfurization (desulfurization efficiency ≥95%), it can be used for heating or power generation.

[0044] Preparation of bio-organic fertilizer: Dry part of the biomass (moisture content 30%-50%) at 60-80℃ for 4-6 hours, crush to a particle size ≤2mm, add straw powder, humic acid and other auxiliary materials (mass ratio 3:1:1), and compost for 7-10 days to produce bio-organic fertilizer with total nitrogen, phosphorus and potassium content ≥5% and organic matter content ≥45%.

[0045] Extraction of microalgae oil: Dry the biomass to a moisture content <20%, use n-hexane as the extracting agent (solid-liquid ratio 1:5), extract at 50℃ for 2 hours, and obtain microalgae oil (extraction rate about 15%-20%) after centrifugal separation, which can be used for the preparation of biodiesel; the residue after extraction can still be mixed with other raw materials to produce organic fertilizer, without waste.

[0046] Although embodiments of the present application have been shown and described, it is to be understood that various modifications, substitutions, replacements and variations can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A method for the synergistic application of algae and bacteria in the treatment of livestock and poultry breeding wastewater, characterized in that, Includes the following steps: S1: Strengthen the pretreatment steps, and sequentially perform solid-liquid separation, demulsification and oil removal, and water quality equalization on livestock and poultry breeding wastewater; S2: Algae-bacteria co-treatment step, the pretreated wastewater is introduced into the reactor and reacted with the modified immobilized algae-bacteria symbiotic system to efficiently remove organic matter, nitrogen and phosphorus from the wastewater; During the contact reaction process, the following intelligent closed-loop control sub-steps are performed: S21: A solar photovoltaic power generation system equipped with a maximum power point tracking controller is used to provide stable operating power for the reactor and its supporting equipment; S22: Using an LED light source with adjustable light quality, intensity and duration, precise artificial lighting is provided for the algae-bacteria symbiotic system in the reactor. S23: Real-time monitoring of water quality parameters in the reactor, including ammonia nitrogen concentration, total phosphorus concentration, COD, dissolved oxygen, and pH value; S24: Based on the water quality parameters monitored in S23, dynamically adjust the illumination parameters of the LED light source, the stirring rate of the reactor, the start / stop and intensity of auxiliary aeration, and the temperature inside the reactor.

2. The method for applying algae-bacteria synergy in treating livestock and poultry breeding wastewater according to claim 1, characterized in that: In S24, the dynamic control of the illumination parameters of the LED light source specifically includes: adjusting the output intensity ratio of red light and blue light in the LED light source according to the monitored ammonia nitrogen concentration; when the ammonia nitrogen concentration is higher than the first set threshold, increasing the output intensity of the blue light component to enhance the nitrification of algae.

3. The method for applying algae-bacteria synergy in treating livestock and poultry breeding wastewater according to claim 1, characterized in that: In S24, the dynamic control of the start and stop of the auxiliary aeration specifically includes: when the detected dissolved oxygen concentration is lower than the second set threshold, starting the microbubble aeration device to provide auxiliary oxygen supply; when the dissolved oxygen concentration recovers to the third set threshold, stopping the aeration.

4. The method for applying algae-bacteria synergy in treating livestock and poultry breeding wastewater according to claim 1, characterized in that: The immobilized algae-bacterial symbiotic system is an algae-bacterial gel particle encapsulating Chlorella and nitrifying bacteria, or a three-dimensional elastic filler with an algae-bacterial biofilm attached.

5. The method for applying algae-bacteria synergy in treating livestock and poultry breeding wastewater according to claim 1, characterized in that: The contact reaction process also includes a temperature control sub-step: using photovoltaic power to drive a heating or cooling device to maintain the temperature inside the reactor within a constant range of 20-30°C.

6. The method for applying algae-bacteria synergy in treating livestock and poultry breeding wastewater according to claim 1, characterized in that: Following the algae-bacteria synergistic treatment step, the method further includes: S3: Solid-liquid separation step, which separates the treated water from the algae and bacteria biomass; S4: Resource recovery step, which involves anaerobic fermentation of the separated algae and bacteria biomass to produce biogas, or drying it to produce bio-fertilizer.