A system and method for treating rural grey water using bacterial and algal symbiosis

Abstract

The present invention relates to the technical field of sewage treatment, and discloses a system and method for treating rural grey water by using bacteria-algae symbiosis, including a mixing tank for collecting mixed grey water; a bacteria-algae symbiotic system, one side of the bacteria-algae symbiotic system is connected to the mixing tank through a first pipeline, a water inlet valve and a water inlet pump are installed on the first pipeline, and the other side of the bacteria-algae symbiotic system is connected to a disinfection system through a second pipeline, and a water outlet valve is installed on the second pipeline; a return pipe, one end of the return pipe is connected to the first pipeline and is located between the water inlet valve and the water inlet pump, and the other end of the return pipe is connected to the second pipeline and is located between the bacteria-algae symbiotic system and the water outlet valve, and a return valve is installed on the return pipe. The present invention realizes the efficient removal of different pollutants in rural grey water, and at the same time, the bacteria-algae symbiotic technology is a water treatment technology with simple operation, mild reaction conditions and environmental friendliness, and its characteristics are suitable for rural grey water treatment and reuse.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and in particular to a system and method for treating rural grey water by utilizing bacteria-algae symbiosis. Background Art

[0002] Greywater refers to domestic sewage discharged from residences, public buildings and other places that is not contaminated by feces and urine. It mainly includes washing, washing and kitchen sewage. After being treated to meet specific requirements, it has good reuse value. At present, the treatment of rural domestic sewage mainly targets black water, that is, the flushing water formed after the water toilet is converted. The treatment method of greywater, which accounts for 60%-70% of domestic sewage, mostly stays in direct dumping or direct use for flushing toilets, which pollutes the rural living environment and regional watersheds. Finding a suitable method to treat rural greywater can greatly improve the effect of improving the rural living environment. As a region dominated by the primary industry, rural areas use a huge amount of water for irrigation and animal husbandry. Greywater is a sewage source with a large amount of water, a relatively low degree of pollution, and is easy to reuse. Treating it and reusing it for non-drinking water scenarios such as farmland irrigation and flushing toilets can effectively help alleviate the problem of water shortage in rural areas and even in China as a whole.

[0003] At present, the commonly used gray water treatment methods mainly include physical and chemical treatment, biological treatment and ecological treatment. But in general, there are still a series of problems in the common treatment methods that restrict their application and promotion. Biological treatment is to use the adsorption and oxidation of microorganisms in water to decompose pollutants in water, thereby improving the water quality of treated water. Among them, bacteria and algae are the main organisms in the application process of the two treatment technologies. The combination of the two can play their strengths and avoid weaknesses in practical applications, and better play their removal effects. Through the symbiotic effect of the two: algae absorb carbon dioxide and other inorganic substances in the environment under the action of light, and convert them into oxygen and biomass, while oxygen and organic matter can be used by bacteria, and at the same time, N, P and other toxins in the environment are degraded, and the generated carbon dioxide continues to be used by algae, forming a virtuous cycle, which can achieve green and environmentally friendly sustainable treatment effects. Combined with the discharge and water quality characteristics of rural gray water, the low-cost and simple operation and management of bacteria and algae symbiotic water treatment system is developed according to local conditions, which is of great significance to improving the regional water environment protection model and saving water resources.

[0004] Therefore, there is an urgent need for a system and method for treating rural grey water using bacteria-algae symbiosis to solve the above-mentioned problems. Summary of the invention

[0005] The purpose of the present invention is to provide a system and method for treating rural grey water using bacteria-algae symbiosis to solve the problems existing in the above-mentioned prior art. The changes in the COD, ammonia nitrogen, total phosphorus and LAS concentrations in the effluent of the bacteria-algae symbiotic reactor are used as the basis for regulation to achieve refined regulation and efficiently remove different pollutants in rural grey water, thereby realizing the reuse of rural grey water and saving water resources.

[0006] To achieve the above object, the present invention provides the following solution: The present invention provides a system for treating rural grey water by using bacteria-algae symbiosis, comprising:

[0007] a mixing tank to collect mixed grey water;

[0008] A bacteria-algae symbiotic system, wherein one side of the bacteria-algae symbiotic system is connected to the mixing tank via a first pipeline, a water inlet valve and a water inlet pump are installed on the first pipeline, and the other side of the bacteria-algae symbiotic system is connected to a disinfection system via a second pipeline, a water outlet valve is installed on the second pipeline;

[0009] A reflux pipe, one end of which is connected to the first pipe and is located between the water inlet valve and the water inlet pump, the other end of which is connected to the second pipe and is located between the bacteria-algae symbiosis system and the water outlet valve, and a reflux valve is installed on the reflux pipe.

[0010] Preferably, the bacteria-algae symbiotic system includes a bacteria-algae symbiotic unit and a water reservoir connected to the bacteria-algae symbiotic unit, the first pipe and the second pipe are connected to the water reservoir respectively, an aerated sand tray is provided in the bacteria-algae symbiotic unit, the aerated sand tray is connected to an air compressor via a third pipe, and an air flow meter is installed on the third pipe.

[0011] Preferably, the water reservoir is provided with an observation port, an electronic display screen and a sensor module, and the detection end of the sensor module extends into the water reservoir.

[0012] Preferably, a grid is connected to one side of the mixing tank, the grid is connected to a lifting pump, and a dosing pump and a dosing tank are installed on the mixing tank.

[0013] Preferably, it also includes a control device, and the lifting pump, the grille, the dosing pump, the dosing tank, the water inlet valve, the water inlet pump, the bacteria-algae symbiosis system, the disinfection system, the water outlet valve and the reflux valve are electrically connected to the control device respectively.

[0014] Preferably, the sensor module includes a COD sensor, an ammonia nitrogen sensor, a total phosphorus sensor, a LAS sensor, a pH sensor and a temperature sensor, which are respectively used to monitor the COD, ammonia nitrogen, total phosphorus, LAS, pH and temperature of the gray water in the reservoir.

[0015] A method for treating rural grey water by using bacteria-algae symbiosis comprises the following steps:

[0016] S1, collecting grey water into the mixing tank and adding flocculant for mixing;

[0017] S2, the mixed grey water is transported to the bacteria-algae symbiotic system for treatment;

[0018] S3. The treated grey water is disinfected by the disinfection system and then used.

[0019] Preferably,

[0020] In step S2, the grey water first enters the sequential treatment stage:

[0021] The grey water is mixed with a coagulant and transported to the bacteria-algae symbiotic system. When the amount of stored water in the bacteria-algae symbiotic system reaches the maximum water level, the outlet valve and the return valve are closed, and the grey water reacts through the bacteria-algae symbiotic system. When the detected values ​​of the outlet COD, ammonia nitrogen, total phosphorus, and LAS concentrations in the bacteria-algae symbiotic system are less than the set values ​​and the concentrations remain stable, the outlet valve is opened to discharge the grey water into the disinfection system.

[0022] Preferably,

[0023] Loop processing phase:

[0024] In the sequential treatment stage, when the COD, ammonia nitrogen, total phosphorus and LAS concentration detection values ​​of the effluent of the bacteria-algae symbiotic system are greater than the set values ​​and show a continuous increasing trend, the circulation treatment stage is entered, the reflux valve is opened, and the gray water in the bacteria-algae symbiotic system re-enters the bacteria-algae symbiotic system through the reflux pipe for reaction, and the sequential treatment stage is entered when the COD, ammonia nitrogen, total phosphorus and LAS concentration detection values ​​of the effluent of the bacteria-algae symbiotic system are less than the set values ​​and the concentrations remain stable.

[0025] Preferably,

[0026] Intensive treatment stage:

[0027] In the circulation treatment stage, when the COD, ammonia nitrogen, total phosphorus and LAS concentration detection values ​​of the effluent from the bacteria-algae symbiotic system are equal to the set values, the enhanced treatment stage is entered, the outlet valve is closed, the return valve is opened, and the effluent from the bacteria-algae symbiotic system re-enters the bacteria-algae symbiotic system through the return pipe until the effluent COD, ammonia nitrogen, total phosphorus and LAS concentration detection values ​​of the bacteria-algae symbiotic system are greater than the set values, the circulation treatment stage is entered, and when the COD, ammonia nitrogen, total phosphorus and LAS concentration detection values ​​of the effluent from the bacteria-algae symbiotic system are less than the set values ​​and the concentrations remain stable, the sequential treatment stage is entered.

[0028] Compared with the prior art, the present invention has the following advantages and technical effects:

[0029] The present invention provides a system and method for treating rural grey water by using bacteria-algae symbiosis. The grey water is collected in a mixing pool and a coagulant is added for mixing. After mixing, the grey water is transported to the bacteria-algae symbiotic system. The bacteria and algae are used to treat the grey water. The bacteria and algae coexist synergistically, and resources are reused indirectly. After treatment, the grey water is disinfected by a disinfection system and then recycled for reuse. In the bacteria-algae symbiotic system, algae absorb carbon dioxide and other inorganic substances in the environment under the action of light and convert them into oxygen and biomass, which can be used by bacteria. At the same time, COD, ammonia nitrogen, total phosphorus, LAS and other toxins are degraded, and the generated carbon dioxide continues to be used by algae to form a virtuous cycle, which can achieve a green, environmentally friendly and sustainable treatment effect. It is an environmentally friendly process, and fine regulation is performed according to different types of pollutants in rural grey water. The regulation system is simple to operate, the reaction conditions are mild, it is environmentally friendly, the treatment cost is low, and it has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative labor:

[0031] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0032] Figure 2 This is a schematic diagram of the structure of the bacteria-algae symbiotic system of the present invention;

[0033] Figure 3 This is a diagram showing the actual effect of preparing the immobilized gel of the present invention;

[0034] Figure 4 This is a dissolution rate test diagram of the SA immobilized beads of the present invention;

[0035] Figure 5 This is a dissolution rate detection diagram of the PVA-SA immobilized beads of the present invention;

[0036] Figure 6 This is a pollutant removal effect diagram of different ratios of bacteria and algae under the immobilization conditions of the present invention;

[0037] Figure 7 This is a diagram showing the pollutant removal effect under different LAS concentration stresses of the present invention;

[0038] Figure 8 This is a diagram showing the pollutant removal effect under different hydraulic loads during continuous operation of the present invention;

[0039] Fig. 9 This is a pollutant removal effect diagram under different LAS impact loads during continuous operation of the present invention;

[0040] Among them, 1. lifting pump; 2. screen; 3. dosing pump; 4. dosing tank; 5. mixing tank; 6. water inlet valve; 7. water inlet pump; 8. bacteria-algae symbiosis system; 81. bacteria-algae symbiosis unit; 82. reservoir; 83. aeration sand table; 84. air compressor; 85. air flow meter; 86. observation port; 87. electronic display screen; 88. sensor module; 9. disinfection system; 10. water outlet valve; 11. reflux pipe; 12. reflux valve; 13. control device. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0043] Reference Figure 1-Figure 9 The present invention provides a system for treating rural grey water by using bacteria-algae symbiosis, comprising:

[0044] A mixing tank 5 for collecting mixed grey water;

[0045] A bacteria-algae symbiotic system 8, one side of the bacteria-algae symbiotic system 8 is connected to the mixing tank 5 through a first pipeline, a water inlet valve 6 and a water inlet pump 7 are installed on the first pipeline, and the other side of the bacteria-algae symbiotic system 8 is connected to a disinfection system 9 through a second pipeline, and a water outlet valve 10 is installed on the second pipeline;

[0046] The reflux pipe 11 has one end connected to the first pipe and located between the water inlet valve 6 and the water inlet pump 7 , and the other end connected to the second pipe and located between the bacteria-algae symbiotic system 8 and the water outlet valve 10 . A reflux valve 12 is installed on the reflux pipe 11 .

[0047] A further optimized solution is that the bacteria-algae symbiotic system 8 includes a bacteria-algae symbiotic unit 81 and a water reservoir 82 connected to the bacteria-algae symbiotic unit 81, the first pipe and the second pipe are connected to the water reservoir 82 respectively, an aerated sand tray 83 is provided in the bacteria-algae symbiotic unit 81, the aerated sand tray 83 is connected to an air compressor 84 via a third pipe, and an air flow meter 85 is installed on the third pipe.

[0048] The bacteria-algae symbiotic unit 81 in one embodiment of the present invention is prepared by the cross-linking effect of polyvinyl alcohol, sodium alginate and calcium chloride, that is, the concentrated algae suspension and the activated sludge concentrate are mixed according to a mass ratio, and then mixed with a sodium alginate SA matrix to form a mixed solution, and a cross-linking operation is performed to obtain a bacteria-algae symbiosis, wherein the bacteria-algae ratio is 1:3, the SA ratio is SA concentration of 2%-3%, the corresponding CaCl2 concentration is 2%-3%, and the PVA concentration is 10%-12%.

[0049] The activated sludge was collected from the aerobic treatment unit of the sewage plant, and was acclimated and cultured by inoculating gray water prepared in the laboratory. The activated sludge in the logarithmic growth phase was centrifuged at 4000 rpm using a low-temperature centrifuge, and resuspended with deionized water to obtain an activated sludge concentrate.

[0050] The bacteria-algae symbiotic unit 81 maintains a certain level of aeration and illumination. LED lamps are used on both sides to provide illumination. The illumination intensity is 200 μmol m-2 s-1, and the light-dark ratio is 6h:6h. An aeration sandbox 83 is used for aeration. Aeration is performed during the light period and is intermittent during the dark period. During aeration, the air compressor 84 and the air flow meter 85 are turned on and controlled by the control device 13.

[0051] To further optimize the solution, an observation port 86 , an electronic display screen 87 and a sensor module 88 are provided on the water reservoir 82 , and a detection end of the sensor module 88 extends into the water reservoir 82 .

[0052] The water level change can be observed through the observation port 86, and the pressure sensor on the upper part of the water reservoir 82 can monitor the water level. At the same time, automatic monitoring is performed through the electronic display screen 87, and the water level is automatically regulated by the control device 13. When the water reservoir 82 reaches the highest water level, the water inlet valve 6 is closed to stop water inlet, and when the water reservoir 82 reaches the lowest water level, the water outlet valve 10 is closed to stop water outlet. At the same time, manual water inlet and outlet buttons are provided to cope with emergencies.

[0053] According to a further optimized solution, a grille 2 is connected to one side of the mixing tank 5 , a lifting pump 1 is connected to the grille 2 , and a dosing pump 3 and a dosing tank 4 are installed on the mixing tank 5 .

[0054] The flocculant in the dosing tank 4 is selected from aluminum series flocculants.

[0055] In one embodiment of the present invention, the disinfection system 9 selects an ultraviolet disinfection system. The disinfection system starts ultraviolet irradiation when the water outlet valve 10 is opened, and turns off the ultraviolet irradiation when the water outlet valve 10 is closed. The system is controlled by the regulating device 13. The molecular structure of DNA or RNA in the cells of the microorganism is destroyed by ultraviolet irradiation, causing growth cell death and / or regenerative cell death, thereby achieving the effect of sterilization and disinfection.

[0056] A further optimized solution also includes a control device 13, and the lifting pump 1, the screen 2, the dosing pump 3, the dosing tank 4, the water inlet valve 6, the water inlet pump 7, the bacteria-algae symbiosis system 8, the disinfection system 9, the water outlet valve 10 and the reflux valve 12 are electrically connected to the control device 13 respectively.

[0057] To further optimize the solution, the sensor module 88 includes a COD sensor, an ammonia nitrogen sensor, a total phosphorus sensor, a LAS sensor, a pH sensor and a temperature sensor, which are used to monitor the COD, ammonia nitrogen, total phosphorus, LAS, pH and temperature of the gray water in the reservoir 82 respectively.

[0058] In one embodiment of the present invention, the equipment is operated in an intermittent mode with downward flow, an operation cycle of 12 hours, and two cycles per day.

[0059] Water volume design:

[0060] Daily water consumption for flushing toilets: Calculated based on the need for each person to urinate three times and defecate once a day, the flushing water volume for each urination is 3L, and the flushing water volume for each defecation is 4.5L. The daily water consumption for flushing toilets per household is 40.5-54L.

[0061] Water supply: The per capita grey water discharge in rural areas excluding kitchen water is 18-60L / person / d, and the total discharge is 54-240L / d; if kitchen water is included, the discharge is 30-80L / person / d, and the total discharge is 90-320L / d. It can be seen that it is completely sufficient to reuse rural grey water for flushing toilets, calculated according to the maximum water supply of 240L.

[0062] Equipment reactor part size design:

[0063] When the substrate is algae particles: the daily water treatment volume is the water supply volume, that is, 240L. When the HRT is 12h, the water treatment volume is 120L. If the requirements of reuse for flushing toilets are met, the reactor volume is 0.2m3, and the design size is 0.8m*0.4m*0.8m according to the redundancy of 20%.

[0064] The automatic control process must complete the water inlet task at a fixed time, regardless of the amount of water in the water tank, and ensure safe water inlet, without water pump idling failure, and without water tank and reactor overflow failure.

[0065] The automatic control process should set a fixed time for drainage, that is, to ensure the stability of HRT.

[0066] Manually controllable parts are required: respectively control the programs or switches of the water tank inlet valve, outlet valve and water pump.

[0067] A method for treating rural grey water by using bacteria-algae symbiosis comprises the following steps:

[0068] S1, the grey water is collected into a mixing tank 5 and a flocculant is added for mixing;

[0069] S2, the mixed grey water is transported to the bacteria-algae symbiotic system 8 for treatment;

[0070] S3. The treated grey water is disinfected by the disinfection system 9 and then used.

[0071] The lifting pump 1 lifts the rural grey water. The grey water delivered by the lifting pump 1 is mixed in the mixing tank 5 by the screen 2 and the dosing pump 3 through the dosing tank 4 with a certain concentration of flocculant. The mixed grey water flows through the inlet valve 6 and is delivered to the reservoir 82 by the inlet pump 7. When the water volume in the reservoir 82 reaches the maximum water level, the outlet valve 10 and the return valve 12 are closed. The grey water in the reservoir 82 is reacted with bacteria and algae. When the COD, ammonia nitrogen, total phosphorus and LAS concentrations of the effluent are detected, When the measured value is less than the set value and the concentration remains stable, the outlet valve 10 is opened, and the lifting pump 1, the grille 2, the dosing pump 3, the dosing tank 4, the mixing tank 5, the water inlet valve 6 and the water inlet pump 7 are closed; when the water storage tank 82 reaches the lowest water level, the outlet valve 10 is closed, the lifting pump 1, the grille 2, the dosing pump 3, the dosing tank 4, the mixing tank 5, the water inlet valve 6 and the water inlet pump 7 are opened, and the water inflows into the water storage tank 82 and is stored. The water discharged from the outlet valve 10 is disinfected by the disinfection system 9 and then used for toilet flushing, etc.

[0072] To further optimize the solution,

[0073] In step S2, the grey water first enters the sequential treatment stage:

[0074] The grey water is mixed with the coagulant and transported to the bacteria-algae symbiotic system 8. When the water storage volume in the bacteria-algae symbiotic system 8 reaches the maximum water level, the outlet valve 10 and the return valve 12 are closed, and the grey water reacts through the bacteria-algae symbiotic system 8. When the detected concentrations of COD, ammonia nitrogen, total phosphorus, and LAS in the effluent of the bacteria-algae symbiotic system 8 are less than the set values ​​and the concentrations remain stable, the outlet valve 10 is opened to discharge the grey water to the disinfection system 9.

[0075] The set values ​​of COD, ammonia nitrogen, total phosphorus and LAS concentrations of the effluent should meet the requirements for flushing toilets and vehicles. The detected values ​​of COD, ammonia nitrogen, total phosphorus and LAS concentrations are the actual reactions in the bacteria-algae symbiosis system 8 and the COD, ammonia nitrogen, total phosphorus and LAS contents detected by the sensor module 88.

[0076] To further optimize the solution,

[0077] Loop processing phase:

[0078] In the sequential treatment stage, when the COD, ammonia nitrogen, total phosphorus, and LAS concentration detection values ​​of the effluent of the bacteria-algae symbiotic system 8 are greater than the set values ​​and show a continuous increasing trend, the circulation treatment stage is entered, and the reflux valve 12 is opened, and the gray water in the bacteria-algae symbiotic system 8 re-enters the bacteria-algae symbiotic system 8 through the reflux pipe 11 for reaction. When the COD, ammonia nitrogen, total phosphorus, and LAS concentration detection values ​​of the effluent of the bacteria-algae symbiotic system 8 are less than the set values ​​and the concentrations remain stable, the sequential treatment stage is entered.

[0079] In the sequential treatment stage, when the concentration detection values ​​of various pollutants in the effluent of the bacteria-algae symbiotic system 8 are greater than the set values ​​and show a continuous increasing trend, the system enters the circulation treatment stage. At this time, the lifting pump 1, the grille 2, the dosing pump 3, the dosing tank 4, the mixing tank 5, the water inlet valve 6 and the water inlet pump 7 are closed, and the reflux valve 12 is opened. The effluent of the bacteria-algae symbiotic system 8 passes through the reflux pipe 11 and the water inlet pump 7 to re-enter the bacteria-algae symbiotic system 8. When the COD, ammonia nitrogen, total phosphorus and LAS concentration detection values ​​of the effluent of the bacteria-algae symbiotic system 8 are less than the set values ​​and the concentrations remain stable, the water outlet valve 10 is opened, the water inlet valve 6 and the reflux valve 12 are closed, and the control system enters the sequential treatment stage. When the water storage tank 82 in the bacteria-algae symbiotic system 8 reaches the lowest water level, the water outlet valve 10 is closed, the lifting pump 1, the grille 2, the dosing pump 3, the dosing tank 4, the mixing tank 5, the water inlet valve 6 and the water inlet pump 7 are opened, and the water storage tank 82 is filled with water for storage.

[0080] To further optimize the solution,

[0081] Intensive treatment stage:

[0082] In the circulation treatment stage, when the COD, ammonia nitrogen, total phosphorus, and LAS concentration detection values ​​of the effluent from the bacteria-algae symbiotic system 8 are equal to the set values, the enhanced treatment stage is entered, the outlet valve 10 is closed, and the return valve 12 is opened, and the effluent from the bacteria-algae symbiotic system 8 re-enters the bacteria-algae symbiotic system 8 through the return pipe 11, until the COD, ammonia nitrogen, total phosphorus, and LAS concentration detection values ​​of the effluent from the bacteria-algae symbiotic system 8 are greater than the set values, the circulation treatment stage is entered, and when the COD, ammonia nitrogen, total phosphorus, and LAS concentration detection values ​​of the effluent from the bacteria-algae symbiotic system 8 are less than the set values ​​and the concentrations remain stable, the sequential treatment stage is entered.

[0083] In the circulation treatment stage, when the COD, ammonia nitrogen, total phosphorus, and LAS concentration detection values ​​of the effluent of the bacteria-algae symbiotic system 8 are equal to the set values, the system enters the enhanced treatment stage through the control device 13. At this time, the outlet valve 10 is closed, the lifting pump 1, the grille 2, the dosing pump 3, the dosing tank 4, the mixing tank 5, the inlet valve 6, the inlet pump 7, and the return valve 12 are opened. At the same time, the effluent of the bacteria-algae symbiotic system 8 re-enters the bacteria-algae symbiotic system 8 through the return pipe 11 and the inlet pump 7 until the COD, ammonia nitrogen, total phosphorus, and LAS concentration detection values ​​of the effluent of the bacteria-algae symbiotic system 8 are greater than the set values. The control system enters the circulation treatment stage. At this time, the lifting pump 1, the grille 2, the dosing pump 3, The dosing tank 4 and the mixing tank 5 stop, the inlet valve 6 and the outlet valve 10 are closed, the reflux valve 12 is opened, and the effluent from the bacteria-algae symbiosis system 8 passes through the reflux pipe 11 and the inlet pump 7 to re-enter the bacteria-algae symbiosis system 8; when the COD, ammonia nitrogen, total phosphorus, and LAS concentration detection values ​​of the effluent from the bacteria-algae symbiosis system 8 are less than the set values ​​and the concentrations remain stable, the control system enters the sequential processing stage, at which time the outlet valve 10 is opened, the inlet valve 6 and the reflux valve 12 are closed, and when the water storage tank 82 in the bacteria-algae symbiosis system 8 reaches the lowest water level, the outlet valve 10 is closed, and the lifting pump 1, the grille 2, the dosing pump 3, the dosing tank 4, the mixing tank 5, the inlet valve 6, the inlet pump 7, and the reflux valve 12 are opened.

[0084] Based on the rural grey water generation, daily toilet flushing water consumption and water use patterns obtained from previous surveys, the flooding operation and emptying oxygen absorption times were set to strengthen the oxygenation of the bacteria-algae symbiotic system and achieve effective removal of pollutants without aeration.

[0085] The simulated rural grey water was used as the inlet water. Glucose was used as the carbon source, ammonium chloride was used as the nitrogen source, potassium dihydrogen phosphate was used as the phosphorus source, and sodium dodecylbenzene sulfonate was used as the LAS source.

[0086] Table 1 Configuration of grey water inlet water quality

[0087]

[0088] The following steps are used to prepare the bacterial-algal symbiosis: Using a low-temperature centrifuge, the protein ball Chlorella in the logarithmic growth period is centrifuged at 4000rpm, and resuspended with deionized water to obtain a concentrated algae suspension with a cell density of 108cell / ml protein ball Chlorella cells. Using a low-temperature centrifuge, the activated sludge in the logarithmic growth period is centrifuged at 4000rpm, and resuspended with deionized water to obtain an activated sludge concentrate. The concentrated algae suspension is mixed with the activated sludge concentrate according to a mass ratio; the mixed concentrate is mixed with SA or SA-PVA matrix to form a mixed solution, and dripped into the CaCl2 solution through a peristaltic pump to obtain bacterial-algal symbiotic gel beads. By comparison, the optimal SA ratio is that the SA concentration needs to be about 2%-3%, the corresponding CaCl2 concentration is 2%-3%, and the optimal PVA concentration needs to be 10%-12%.

[0089] A photobioreactor PBR is set up, and gray water is added through the raw water tank; aeration is provided for the PBR reactor; the PBR reactor is operated in a constant temperature laboratory. The reactor is cylindrical, with a total volume of 5L, an effective volume of 4L, a height of 50cm, and a diameter of 10cm; the raw water tank is cylindrical, with a height of 80cm and a diameter of 50cm; white LED lamps are used on both sides of the reactor to provide light, and the light-dark ratio is 6h:6h, which is switched every six hours; aeration is intermittently aerated through an aeration sandbox 83, with aeration during light periods and intermittent during dark periods. The constant temperature PBR reactor is achieved by a heating rod to maintain a constant temperature of 25℃; the bacteria-algae symbiosis unit 81 part of the bacteria-algae symbiosis system 8 is constructed.

[0090] In the fine control process of the method for treating simulated rural greywater, the control system first operates in a sequential treatment stage, at which the outlet valve 10 is opened, the lifting pump 1, the grille 2, the dosing pump 3, the dosing tank 4, the mixing tank 5, the inlet valve 6 and the inlet pump 7 are opened, and the outlet valve 10 and the return valve 12 are closed. The corresponding bacteria-algae symbiotic system is inoculated into the bacteria-algae symbiotic system 8, and the reactor is placed in an environment of 25°C, light: dark = 6: 6, switched every six hours, and each time the water inlet and outlet are 2L, and the cycle is 1d. The inlet and outlet water of the reactor are controlled by a peristaltic pump and a solenoid valve, respectively. The peristaltic pump and the solenoid valve are controlled by a time-controlled switch, and the water inlet time is about 5min and the water outlet time is about 2min. After the reactor runs stably, sampling is performed regularly at fixed time points. The sampling point is located at the drain outlet of the infiltration tank, and the raw water is directly collected from the sewage tank. For static and dynamic tests, 50 mL of water was sampled each time, and the water samples were placed in a refrigerator at 4°C. The conventional indicators CODCr, NH4+-N, TP and LAS were tested within 24 hours. Each sample was 50 ml, and the sampling time was 1 hour, 3 hours, 6 hours, 12 hours, 18 hours, and 24 hours after the water entered, in order to observe the removal of COD, nitrogen, phosphorus and LAS in the water.

[0091] The removal effects of the immobilized bacteria-algae symbiotic system 8 on the main pollutants in the simulated rural grey water were COD: 87.5±2.89%, ammonia nitrogen: 65.34±2.0%, TP: 60.4%±4.29%, and LAS: 91.07%±2.04%. The removal rates of COD, ammonia nitrogen, and total phosphorus were less than 90%, and the COD content was greater than 10 mg / L, which could not meet the requirements of flushing toilets and vehicles. At this time, when the concentration detection values ​​of various pollutants in the effluent of the bacteria-algae symbiotic system 8 are greater than the set values ​​and show a continuous increasing trend, the control system enters the circulation treatment stage. At this time, the lifting pump 1, the grille 2, the dosing pump 3, the dosing tank 4, the mixing tank 5, the water inlet valve 6 and the water inlet pump 7 are closed, and the reflux valve 12 is opened. The effluent of the bacteria-algae symbiotic system 8 re-enters the bacteria-algae symbiotic system 8 through the reflux pipe 11 and the water inlet pump 7; when the concentration detection values ​​of COD, ammonia nitrogen, total phosphorus and LAS in the effluent of the bacteria-algae symbiotic system 8 are less than the set values ​​and the concentrations remain stable, the effluent Valve 10 is opened, inlet valve 6 and return valve 12 are closed, and the control system enters the sequential treatment stage. When the water storage tank 82 in the bacteria-algae symbiotic system 8 reaches the lowest water level, the outlet valve 10 is closed, the lifting pump 1, the grille 2, the dosing pump 3, the dosing tank 4, the mixing tank 5, the inlet valve 6 and the inlet pump 7 are opened, and the water storage tank 82 is filled with water; until the COD, ammonia nitrogen, total phosphorus, and LAS concentration detection values ​​of the outlet water of the bacteria-algae symbiotic system 8 are equal to the set values, the control system enters the enhanced treatment stage, at this time, the outlet valve 10 is closed, the lifting pump 1, the grille 2, the total phosphorus, and the LAS concentration detection values ​​of the outlet water of the bacteria-algae symbiotic system 8 are equal to the set values, and the control system enters the enhanced treatment stage. The dosing pump 3, the dosing tank 4, the mixing tank 5, the water inlet valve 6, the water inlet pump 7 and the reflux valve 12 are turned on, and at the same time, the effluent of the bacteria-algae symbiotic system 8 re-enters the bacteria-algae symbiotic system 8 through the reflux pipe 11 and the water inlet pump 7, until the COD, ammonia nitrogen, total phosphorus and LAS concentration detection values ​​of the effluent of the bacteria-algae symbiotic system 8 are less than the set values, the control system enters the circulation treatment stage, at this time, the lifting pump 1, the grille 2, the dosing pump 3, the dosing tank 4 and the mixing tank 5 are stopped, the water inlet valve 6 and the water outlet valve 10 are closed, the reflux valve 12 is opened, and the effluent of the bacteria-algae symbiotic system 8 is discharged. The water re-enters the bacteria-algae symbiotic system 8 through the return pipe 11 and the water inlet pump 7; when the COD, ammonia nitrogen, total phosphorus, and LAS concentration detection values ​​of the effluent of the bacteria-algae symbiotic system 8 are less than the set values ​​and the concentrations remain stable, the control system enters the sequential treatment stage, at which time the outlet valve 10 is opened, the inlet valve 6 and the return valve 12 are closed, and when the water storage tank 82 in the bacteria-algae symbiotic system 8 reaches the lowest water level, the outlet valve 10 is closed, and the lifting pump 1, the grille 2, the dosing pump 3, the dosing tank 4, the mixing tank 5, the inlet valve 6, the inlet pump 7, and the return valve 12 are opened. The wastewater treated in the circulation treatment stage has the best pollutant removal effect, which is 82.86%, 95.61%, and 94.49% (COD, ammonia nitrogen, and LAS) (hydraulic load is 0.212m 3 / (m 2·d)), the effluent can meet the requirements of "Urban Wastewater Recycling and Urban Miscellaneous Water Quality" (GB / T18920-2020), effectively realizing the reuse of urban and rural grey water and saving water resources.

[0092] According to the above embodiments, the system and method for treating rural grey water by using bacteria-algae symbiosis provided by the present invention can perform fine regulation according to the changes in COD, ammonia nitrogen, total phosphorus, LAS concentration, temperature and pH of the effluent from the bacteria-algae symbiosis system, thereby realizing rapid, economical and effective treatment of rural grey water. The process is simple to operate, has mild reaction conditions and is environmentally friendly, and its characteristics are suitable for rural grey water treatment and reuse.

[0093] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0094] The above embodiments are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for treating rural grey water using bacterial-algal symbiosis, characterized in that: The systems used in this method include: A mixing tank (5) for collecting mixed grey water; A bacteria-algae symbiotic system (8), wherein one side of the bacteria-algae symbiotic system (8) is connected to the mixing tank (5) via a first pipe, and a water inlet valve (6) and a water inlet pump (7) are installed on the first pipe; and the other side of the bacteria-algae symbiotic system (8) is connected to a disinfection system (9) via a second pipe, and a water outlet valve (10) is installed on the second pipe; a return pipe (11), one end of the return pipe (11) being in communication with the first pipeline and being located between the water inlet valve (6) and the water inlet pump (7), the other end of the return pipe (11) being in communication with the second pipeline and being located between the bacteria-algae symbiotic system (8) and the water outlet valve (10), and a return valve (12) being installed on the return pipe (11); A grille (2) is connected to one side of the mixing tank (5), the grille (2) is connected to a lifting pump (1), and a dosing pump (3) and a dosing tank (4) are installed on the mixing tank (5); Also includes a control device (13); The bacteria-algae symbiotic system (8) comprises a bacteria-algae symbiotic unit (81) and a water reservoir (82); The following steps are involved: S1, collecting grey water into the mixing tank (5) and adding flocculant for mixing; S2, the mixed grey water is transported to the bacteria-algae symbiotic system (8) for treatment; S3, the treated grey water is disinfected by the disinfection system (9) and then used; In step S2, the grey water first enters the sequential treatment stage: The grey water is mixed with a coagulant and then transported to the bacteria-algae symbiotic system (8). When the amount of water stored in the bacteria-algae symbiotic system (8) reaches a maximum water level, the outlet valve (10) and the return valve (12) are closed, and the grey water reacts through the bacteria-algae symbiotic system (8). When the COD, ammonia nitrogen, total phosphorus, and LAS concentration detection values ​​of the outlet water in the bacteria-algae symbiotic system (8) are less than the set values ​​and the concentrations remain stable, the outlet valve (10) is opened to discharge the grey water to the disinfection system (9); Loop processing phase: In the sequential treatment stage, when the COD, ammonia nitrogen, total phosphorus, and LAS concentration detection values ​​of the effluent of the bacteria-algae symbiotic system (8) are greater than the set values ​​and show a continuous increasing trend, the circulation treatment stage is entered, the return valve (12) is opened, and the gray water in the bacteria-algae symbiotic system (8) re-enters the bacteria-algae symbiotic system (8) through the return pipe (11) to react, and when the COD, ammonia nitrogen, total phosphorus, and LAS concentration detection values ​​of the effluent of the bacteria-algae symbiotic system (8) are less than the set values ​​and the concentrations remain stable, the sequential treatment stage is entered; Intensive treatment stage: In the circulation treatment stage, when the COD, ammonia nitrogen, total phosphorus, and LAS concentration detection values ​​of the effluent of the bacteria-algae symbiotic system (8) are equal to the set values, the enhanced treatment stage is entered, the outlet valve (10) is closed, the return valve (12) is opened, and the effluent of the bacteria-algae symbiotic system (8) re-enters the bacteria-algae symbiotic system (8) through the return pipe (11), until the COD, ammonia nitrogen, total phosphorus, and LAS concentration detection values ​​of the effluent of the bacteria-algae symbiotic system (8) are greater than the set values, the circulation treatment stage is entered, and when the COD, ammonia nitrogen, total phosphorus, and LAS concentration detection values ​​of the effluent of the bacteria-algae symbiotic system (8) are less than the set values ​​and the concentrations remain stable, the sequential treatment stage is entered; In the circulation treatment stage, when the COD, ammonia nitrogen, total phosphorus, and LAS concentration detection values ​​of the effluent of the bacteria-algae symbiotic system (8) are equal to the set values, the system enters the enhanced treatment stage through the control device (13). At this time, the outlet valve (10) is closed, the lifting pump (1), the screen (2), the dosing pump (3), the dosing tank (4), the mixing tank (5), the inlet valve (6), the inlet pump (7), and the return valve (12) are opened, and at the same time, the effluent of the bacteria-algae symbiotic system (8) re-enters the bacteria-algae symbiotic system (8) through the return pipe (11) and the inlet pump (7) until the COD, ammonia nitrogen, total phosphorus, and LAS concentration detection values ​​of the effluent of the bacteria-algae symbiotic system (8) are greater than the set values. At this time, the control system enters the circulation treatment stage. At this time, the lifting pump (1), the screen (2), the dosing pump (3), the dosing tank (4 ), the mixing tank (5) stops, the inlet valve (6) and the outlet valve (10) are closed, the return valve (12) is opened, and the effluent of the bacteria-algae symbiotic system (8) re-enters the bacteria-algae symbiotic system (8) through the return pipe (11) and the inlet pump (7); when the COD, ammonia nitrogen, total phosphorus, and LAS concentration detection values ​​of the effluent of the bacteria-algae symbiotic system (8) are less than the set values ​​and the concentrations remain stable, the control system enters the sequential treatment stage, at which time the outlet valve (10) is opened, the inlet valve (6) and the return valve (12) are closed, and when the water storage tank (82) in the bacteria-algae symbiotic system (8) reaches the lowest water level, the outlet valve (10) is closed, and the lifting pump (1), the screen (2), the dosing pump (3), the dosing tank (4), the mixing tank (5), the inlet valve (6), the inlet pump (7), and the return valve (12) are opened.

2. The method for treating rural grey water by using bacteria-algae symbiosis according to claim 1, characterized in that: The water reservoir (82) is in communication with the bacteria-algae symbiotic unit (81); the first pipe and the second pipe are respectively in communication with the water reservoir (82); an aerated sand tray (83) is provided in the bacteria-algae symbiotic unit (81); the aerated sand tray (83) is in communication with an air compressor (84) via a third pipe; and an air flow meter (85) is installed on the third pipe.

3. The method for treating rural grey water by using bacteria-algae symbiosis according to claim 2, characterized in that: The water reservoir (82) is provided with an observation port (86), an electronic display screen (87) and a sensor module (88), and a detection end of the sensor module (88) extends into the water reservoir (82).

4. The method for treating rural grey water by using bacteria-algae symbiosis according to claim 1, characterized in that: The lifting pump (1), the grille (2), the dosing pump (3), the dosing tank (4), the water inlet valve (6), the water inlet pump (7), the bacteria-algae symbiotic system (8), the disinfection system (9), the water outlet valve (10) and the reflux valve (12) are respectively electrically connected to the control device (13).

5. The method for treating rural grey water by using bacteria-algae symbiosis according to claim 3, characterized in that: The sensor module (88) comprises a COD sensor, an ammonia nitrogen sensor, a total phosphorus sensor, a LAS sensor, a pH sensor and a temperature sensor, which are respectively used to monitor the COD, ammonia nitrogen, total phosphorus, LAS, pH and temperature of the grey water in the water storage tank (82).

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