CN106745769B

CN106745769B - Solar constant-temperature microalgae cultivation domestic sewage treatment system

Info

Publication number: CN106745769B
Application number: CN201611188240.4A
Authority: CN
Inventors: 王昱; 时文强; 李金平; 连运涛; 卢世国; 任海伟; 郑健; 范严伟
Original assignee: Lanzhou University of Technology
Current assignee: Lanzhou University of Technology
Priority date: 2016-12-21
Filing date: 2016-12-21
Publication date: 2020-06-02
Anticipated expiration: 2036-12-21
Also published as: CN106745769A

Abstract

Solar constant-temperature culture microalgae domestic sewage treatment system, which comprises a sewage inlet filtering pond (1), a sunlight plate sunlight greenhouse (2), a microalgae culture pond (3), a solar heat collection water tank (4), a constant-temperature control system (5) and an outlet filtering pond (6), wherein the sewage inlet filtering pond (1) is communicated with the microalgae culture pond (3), the microalgae culture pond (3) is communicated with the sewage outlet filtering pond (6), the sunlight plate sunlight greenhouse (2) is assembled outside the microalgae culture pond (3) and the constant-temperature control system (5), the solar heat collection water tank (4) is assembled on the upper part of the sunlight plate sunlight greenhouse (2), the solar heat collection water tank (4) is connected with the constant-temperature control system (5), a heat conduction coil (5-5) in the constant-temperature control system is arranged in the microalgae culture pond (3), and the outlet filtering pond (6) is connected with the solar heat collection water tank (4), The microalgae culture pond (3) and the sewage inlet filtering pond (1) are connected with each other.

Description

Solar constant-temperature microalgae cultivation domestic sewage treatment system

Technical Field

The invention relates to an environment protection technology, in particular to a rural sewage treatment technology.

Background

With the acceleration of the pace of urban construction in rural areas in China, the water consumption of residents in the villages and the towns is continuously increased, so that the sewage discharge amount of the villages and the towns is increased year by year. However, the village and town sewage collection system and the harmless treatment facility are seriously deficient, and the domestic sewage treatment rate is less than 2.6 percent. The discharge amount of sewage in villages and towns is rapidly increased, and along with disordered and disordered flow or direct discharge of a large amount of untreated sewage, the environment pollution of a plurality of villages and towns is serious, the crisis of water resource shortage in China is aggravated, and the sustainable development of economy in villages and towns is severely restricted. The purification treatment of domestic sewage becomes one of the problems which need to be solved urgently in the urbanization development of rural areas in China. Rural domestic sewage has the characteristics of uneven discharge, obvious water quantity change and dispersed discharge. The traditional sewage treatment methods mainly comprise a physical treatment method, a chemical treatment method and the like, but the processes have the problems of high energy consumption for sewage treatment, high N, P plasma content in the treated water and high possibility of generating secondary pollution generally, and the methods are not suitable for rural areas generally. Therefore, the research and development of the technology for purifying and treating the domestic sewage in the villages and the towns are urgently needed.

The research direction for purifying and treating domestic sewage in villages and towns at home and abroad mainly aims at biological treatment. Since Oswald proposed the idea of purifying organic and inorganic compounds in sewage by using microalgae in 1957, various domestic and foreign research institutes have conducted a great deal of research on the feasibility, the purification effect of various kinds of sewage, and the like. The results prove that the algae can reduce or recycle various nitrogen and phosphorus nutrients and other organic and inorganic compounds in the sewage through the actions of physical adsorption, biological assimilation, absorption degradation, biological enrichment and the like other microorganisms such as bacteria and the like. Research shows that the growth of microalgae is closely related to the culture environment (illumination, temperature), the culture solution (hydrogen ion concentration index, salinity, CO2 concentration, and nutrient content of the culture medium) and the culture time. The proper illumination intensity and illumination time are beneficial to the growth of the microalgae, and the growth of the microalgae can be influenced by overhigh or overlow illumination. The optimal growth temperature range of most microalgae is 16-27 ℃, and when the temperature is lower than 16 ℃, the microalgae grows slowly; whereas temperatures above 35 ℃ may have lethal effects on some microalgae.

At present, the common modes for purifying and treating sewage by utilizing microalgae mainly comprise stable pond culture, immobilized culture, photobioreactor culture and the like. However, under the influence of environmental factors (light, temperature) and production efficiency, the sewage culture of microalgae is basically studied in a small scale in a laboratory. However, the actual indoor and outdoor conditions are very different, especially the conditions of illumination and temperature, and it is difficult to ensure the optimal growth conditions of microalgae in the laboratory outdoors, thereby limiting the popularization and application of microalgae large-scale culture and sewage purification. Therefore, the project utilizes the characteristic that the economical heat collection temperature of the solar heat collector is matched with the optimum growth temperature of the microalgae, integrates the microalgae culture and the solar heat collector system to purify and treat rural domestic sewage, directly provides solar heat energy for the microalgae, and overcomes the adverse factors of external environments such as season, illumination, temperature and the like when the microalgae is cultured in a large scale; meanwhile, by utilizing the characteristic that carbon, nitrogen, phosphorus and other nutrient substances are required to be consumed in the rapid growth process of the microalgae to synthesize complex organic matters in vivo, carbon, nitrogen and phosphorus elements in the domestic sewage can be adsorbed, and the aim of efficient purification treatment of the domestic sewage in villages and small towns is fulfilled.

Disclosure of Invention

The invention aims to provide a system for treating domestic sewage by culturing microalgae at constant temperature by using solar energy.

The invention relates to a domestic sewage treatment system for culturing microalgae at constant temperature by using solar energy, which comprises a sewage inlet filtering tank, a sunlight plate sunlight greenhouse, a microalgae culturing tank, a solar heat collecting water tank, a constant temperature control system and an outlet filtering tank, wherein the sewage inlet filtering tank is communicated with the microalgae culturing tank, the microalgae culturing tank is communicated with the sewage outlet filtering tank, the sunlight plate sunlight greenhouse is assembled outside the microalgae culturing tank and the constant temperature control system, the solar heat collecting water tank is assembled at the upper part of the sunlight plate sunlight greenhouse, the solar heat collecting water tank is connected with the constant temperature control system, a heat conducting coil in the constant temperature control system is arranged in the microalgae culturing tank, and the outlet filtering tank is connected with the solar heat collecting water tank, the microalgae culturing tank and the sewage inlet filtering tank.

The invention has the beneficial effects that: rural sewage is pretreated through a structure device in a sewage inlet filtering system, suspended matters, BOD, COD and SS in the sewage are effectively removed, large particles and floating objects are removed, the sewage enters a microalgae culture pond in a sunlight greenhouse of a sunlight plate, and after being filtered and adsorbed by a broken straw membrane, biogas fermentation can be carried out; the aim of purifying sewage is achieved by culturing microalgae in a microalgae culture pond, and meanwhile, the optimum conditions of temperature, illumination conditions, hydrogen ion concentration index and sewage dilution are provided for the growth and propagation of microalgae by utilizing a sunlight plate sunlight greenhouse, a solar heat collection water tank and a constant temperature control system. Realizing high-efficiency microalgae cultivation and rural sewage purification, and achieving the purpose of large-scale popularization and application.

Drawings

Fig. 1 is a schematic view of the whole structure flow of the present invention, fig. 2 is a structural view of a sewage inlet filtering tank 1, fig. 3 is a structural view of the inside of a solar panel solar greenhouse 2, fig. 4 is an indoor plan view of the solar panel solar greenhouse 2 of the solar constant temperature microalgae cultivation treatment rural sewage device of the present invention, fig. 5 is a structural view of a constant temperature control system 5, and fig. 6 is a structural view of an outlet filtering tank 6. Fig. 7 is a schematic view of the overall structural framework of the present invention.

Detailed Description

As shown in figure 1, the invention relates to a domestic sewage treatment system for culturing microalgae at constant temperature by using solar energy, which comprises a sewage inlet filtering pond 1, a sunlight plate sunlight greenhouse 2, a microalgae culture pond 3, a solar heat collecting water tank 4, a constant temperature control system 5 and a water outlet filtering pond 6, wherein the sewage inlet filtering pond 1 is communicated with the microalgae culture pond 3, the microalgae culture pond 3 is communicated with the sewage outlet filtering pond 6, the sunlight plate sunlight greenhouse 2 is assembled outside the microalgae culture pond 3 and the constant temperature control system 5, the solar heat collecting water tank 4 is assembled at the upper part of the sunlight plate sunlight greenhouse 2, the solar heat collecting water tank 4 is connected with the constant temperature control system 5, a heat conducting coil pipe 5-5 in the constant temperature control system is placed in the microalgae culture pond 3, and the water outlet filtering pond 6 is connected with the solar heat collecting water tank 4, the microalgae culture pond 3 and the sewage inlet filtering pond 1.

As shown in fig. 2, in the above system for treating domestic sewage by culturing microalgae, the sewage inlet filtering tank 1 comprises a grating 1-1, a grit chamber 1-2, a first crushed straw membrane component 1-3 and a quartz sand filtering tank 1-4, wherein the grating 1-1, the grit chamber 1-2, the crushed straw membrane component 1-3 and the quartz sand filtering tank 1-4 are sequentially arranged from left to right, and the crushed straw membrane component is composed of at least 3 crushed straws, and the aperture of the crushed straw membrane component is sequentially reduced along the water flow direction; the quartz sand filter tank 1-4 consists of a coarse particle size filter layer 1-4-1, a medium particle size filter layer 1-4-2 and a fine particle size filter layer 1-4-3 which are sequentially arranged from top to bottom.

As shown in FIG. 3, in the solar constant temperature microalgae cultivation domestic sewage treatment system, the microalgae cultivation pond 3 is composed of a water quality adjusting pond 3-1, a water quantity adjusting pond 3-2 and a microalgae cultivation channel 3-3.

As shown in fig. 4 and 5, in the system for treating domestic sewage by culturing microalgae with solar energy at constant temperature, the constant temperature control system 5 is formed by connecting a circulating water pump 5-1, a temperature sensor 5-2, a frequency converter 5-3, a temperature controller 5-4 and a heat conduction coil pipe 5-5; the temperature sensor 5-2 is arranged in the microalgae culture channel 3-3 and is connected with the temperature controller 5-4, the temperature controller 5-4 is connected with the frequency converter 5-3, the frequency converter 5-3 is connected with the circulating water pump 5-1, and the circulating water pump 5-1 is connected between the solar heat collection water tank 4 and the heat conducting coil pipe 5-5 to form a circulating loop.

As shown in fig. 2 and 4, in the system for treating domestic sewage by culturing microalgae with constant temperature by using solar energy, the effluent filtering tank 6 is composed of a second crushed straw membrane component 6-1 and an effluent collecting tank 6-2, the second crushed straw membrane component 6-1 is composed of at least 3 crushed straws, the aperture is sequentially reduced along the water flow direction, and the formed aperture is smaller than that formed by the first crushed straw membrane component 1-3.

In order to better exert the filtering effect of the sewage inlet filtering system, as shown in fig. 2, a sand discharge pipeline 1-2-1 is arranged at the bottom of a grit chamber 1-2, and the sediment at the bottom of the grit chamber 1-2 is discharged in time; three filtering membranes are arranged in the first crushed straw membrane component 1-3, the aperture of each filtering membrane is sequentially reduced along the flowing water direction, and impurities in sewage are removed as efficiently as possible; in order to better exert the effect of filtering impurities, the first crushed straw membrane component 1-3 needs to be replaced regularly, and the replaced first crushed straw membrane component 1-3 is transported to a methane tank to be fermented to generate methane; in the quartz sand filtering tank 1-4, in order to prevent the water distribution from being uneven when the flow is small, a water distribution layer 1-4-4 is arranged; in order to remove impurities more effectively, a coarse particle size filter layer 1-4-1, a medium particle size filter layer 1-4-2 and a fine particle size filter layer 1-4-3 are arranged on a quartz sand filter tank 1-4, wherein the filter layer thickness of the coarse particle size filter layer 1-4-1 is 200-300mm, the particle size is 10-20mm, the filter layer thickness of the medium particle size filter layer 1-4-2 is 100-200mm, the particle size is 5-10mm, the filter layer thickness of the fine particle size filter layer 1-4-3 is 50-100mm, and the particle size is 1-5 mm. In order to enable the quartz sand filter tank to work efficiently, a back washing pipeline 1-4-5 is arranged at the bottom of the filter tank, a gate valve 1-4-6 is arranged on a water outlet pipe of the sewage inlet filter tank to cooperate with back washing, and back washing is carried out on a filter layer at regular time, so that the working efficiency of the filter tank is improved.

As shown in figures 3, 4 and 5, the solar greenhouse 2 of the invention is provided with two systems, one is a microalgae breeding and culturing system, namely a microalgae culturing pond 3, and the other is a solar heat collecting water tank 4 and a constant temperature control system 5. The microalgae culture pond 3 comprises a water quality adjusting pond 3-1, a water quantity adjusting pond 3-2 and a microalgae culture channel 3-3; wherein the water quality adjusting tank 3-1 is connected with a water outlet pipe of the sewage inlet filtering tank; a water injection pipeline 3-1-1 from an effluent collecting tank is arranged in the water quality adjusting tank 3-1 to dilute the original sewage; a hydrogen ion concentration index detection and control device 3-1-2 is arranged on the water quality regulating tank 3-1, and is used for detecting and controlling the hydrogen ion concentration index value of the sewage to be 6-8; a stirrer 3-1-3 is arranged on the water quality adjusting tank 3-1 to uniformly mix the sewage concentration; a sewage lifting pump 3-1-4 is arranged on the water quality adjusting tank 3-1 to adjust the sewage from the lower water quality adjusting tank 3-1 to the higher water quantity adjusting tank 3-2. As can be seen from the combination of FIG. 3 and FIG. 4, the water quantity adjusting tank 3-2 is provided with uniform water distribution holes, so that the sewage flowing through the water quantity adjusting tank 3-2 can uniformly flow into the microalgae cultivation channel 3-3, and the sewage flows in an S shape in the microalgae cultivation channel.

In order to better meet the growth conditions of microalgae, as shown in fig. 3, a sunlight plate sunlight greenhouse 2 is designed into a closed form, a transparent sunlight plate 2-1 is adopted at the top of the sunlight plate sunlight greenhouse 2, vent holes 2-3 are arranged on a wall body 2-2 of the sunlight plate sunlight greenhouse, and energy-saving LED lamps 2-4 are arranged on a beam structure of the sunlight plate sunlight greenhouse 2. The transmittance of the transparent sunlight plate 2-1 is 20% -80%, sunlight is used for irradiation in the daytime, when the sunlight is insufficient, the energy-saving LED lamp 2-4 is used for keeping the illumination intensity at 4000-8000lux, and the requirement of microalgae growth and propagation is met; the air vents 2-3 on the wall 2-2 of the sunlight greenhouse of the sunlight plate are used for keeping indoor air circulation and preventing the transparent sunlight plate on the top of the greenhouse from being hardened and exposed to influence the transmission capability of sunlight.

In order to better satisfy the growth conditions of microalgae, as shown in fig. 3, 4 and 5, the constant temperature control system 5 of the invention is connected with the solar heat collection water tank 4. The upper part of the solar heat collection water tank 4 is provided with an overflow pipe 4-2 and a water injection pipe 4-1 connected with an effluent collecting tank 6-2, and the water level in the solar heat collection water tank 4 is controlled; the constant temperature control system 5 is formed by connecting a circulating water pump 5-1, a temperature sensor 5-2, a frequency converter 5-3, a temperature controller 5-4 and a heat conduction coil pipe 5-5; the heat conducting coil 5-5 is connected with the solar heat collecting water tank 4 to form a circulation loop, the temperature sensor 5-2 is arranged in the microalgae culture channel 3-3 and is connected with the temperature controller 5-4, the temperature controller 5-4 is connected with the frequency converter 5-3, the frequency converter 5-3 is connected with the circulating water pump 5-1, the circulating water pump 5-1 is connected to the heat conducting coil 5-5 and the solar heat collecting water tank 4 to form a circulation loop, and hot water is conveyed from the solar heat collecting water tank 4 through the heat conducting coil 5-5 in the microalgae culture channel 3-3 by the circulating water pump 5-1; the temperature controller 5-4 is used for setting the sewage environment inside the microalgae cultivation channel 3-3 to be 25-28 ℃, and in order to ensure that the sewage environment inside the microalgae cultivation channel 3-3 is heated uniformly, the heat conduction coil 5-5 is set to be a spiral coil, so that the contact area with sewage is increased, the heat conduction coil is heated uniformly, and the working efficiency of the heat conduction coil 5-5 is improved.

As shown in fig. 2, 3, 6 and 7, the effluent filtering tank 6 for filtering sewage of the present invention is composed of a crushed straw membrane module 6-1 and an effluent collecting tank 6-2, wherein at least three filtering membranes are arranged in the second crushed straw membrane module 6-1, and the aperture of each filtering membrane is sequentially reduced along the flowing water direction and is smaller than that of the crushed straw membrane module in the sewage inlet filtering tank, so as to efficiently remove microalgae in water; in order to better exert the effect of filtering microalgae, the second crushed straw membrane component 6-1 needs to be replaced periodically, and the replaced second crushed straw membrane component 6-1 is transported to a methane tank to be fermented to generate methane; the water filtered by the microalgae flows into an effluent collecting tank 6-2 and is a backflushing elution water supply source of a solar heat collecting water tank 4, a water quality adjusting tank 3-1 and a quartz sand filtering tank 1-4, wherein the backflushing pipeline 1-4-5 and a water injection pipeline 3-1-1 of the water quality adjusting tank 3-1 come from the same main pipe of the effluent collecting tank 6-2.

Claims

1. Little algae system of domestic sewage of processing is cultivateed to solar energy constant temperature, including sewage filtering ponds (1), sunshine board sunlight greenhouse (2), little algae breed pond (3), solar energy collection water tank (4), constant temperature control system (5) and play water filtering ponds (6), its characterized in that: the sewage inlet filtering pond (1) is communicated with the microalgae breeding pond (3), the microalgae breeding pond (3) is communicated with the sewage outlet filtering pond (6), the sunlight plate sunlight greenhouse (2) is assembled outside the microalgae breeding pond (3) and the constant temperature control system (5), the solar heat collecting water tank (4) is assembled at the upper part of the sunlight plate sunlight greenhouse (2), the solar heat collecting water tank (4) is connected with the constant temperature control system (5), a heat conducting coil (5-5) in the constant temperature control system is placed in the microalgae breeding pond (3), and the outlet filtering pond (6) is connected with the solar heat collecting water tank (4), the microalgae breeding pond (3) and the sewage inlet filtering pond (1);

two major systems are arranged in a sunlight greenhouse (2) of a sunlight plate, one is a microalgae breeding and culturing system, namely a microalgae culture pond (3), and the other is a solar heat collection water tank (4) and a constant temperature control system (5); the microalgae culture pond (3) comprises a water quality adjusting pond (3-1), a water quantity adjusting pond (3-2) and a microalgae culture channel (3-3); wherein the water quality adjusting tank (3-1) is connected with a water outlet pipe of the sewage inlet filtering tank; a water injection pipeline (3-1-1) from an effluent collecting tank is arranged in the water quality adjusting tank (3-1) to dilute the original sewage; a hydrogen ion concentration index detection and control device (3-1-2) is arranged on the water quality adjusting tank (3-1); a stirrer (3-1-3) is arranged on the water quality adjusting tank (3-1); a sewage lifting pump (3-1-4) is arranged on the water quality adjusting tank (3-1) and can adjust sewage from the water quality adjusting tank (3-1) with a lower position to the water quantity adjusting tank (3-2) with a higher position;

the sewage flows in an S shape in the microalgae culture channel.

2. The system for treating domestic sewage through solar constant-temperature culture of microalgae according to claim 1, characterized in that: the sewage inlet filtering tank (1) comprises a grating (1-1), a grit chamber (1-2), a first crushed straw membrane component (1-3) and a quartz sand filtering tank (1-4), wherein the grating (1-1), the grit chamber (1-2), the first crushed straw membrane component (1-3) and the quartz sand filtering tank (1-4) are sequentially arranged from left to right, and the crushed straw membrane component is composed of at least 3 crushed straws, and the aperture of the crushed straw membrane component is sequentially reduced along the water flow direction; the quartz sand filter tank (1-4) consists of a coarse particle size filter layer (1-4-1), a medium particle size filter layer (1-4-2) and a fine particle size filter layer (1-4-3), which are arranged in sequence from top to bottom.

3. The system for treating domestic sewage through solar constant-temperature culture of microalgae according to claim 1, characterized in that: the constant temperature control system (5) is formed by connecting a circulating water pump (5-1), a temperature sensor (5-2), a frequency converter (5-3), a temperature controller (5-4) and a heat conducting coil (5-5); the temperature sensor (5-2) is arranged in the microalgae culture channel (3-3) and is connected with the temperature controller (5-4), the temperature controller (5-4) is connected with the frequency converter (5-3), the frequency converter (5-3) is connected with the circulating water pump (5-1), and the circulating water pump (5-1) is connected between the solar heat collection water tank (4) and the heat conduction coil pipe (5-5) to form a circulating loop.

4. The system for treating domestic sewage through solar constant-temperature culture of microalgae according to claim 1, characterized in that: the effluent filtering tank (6) is composed of a second crushed straw membrane component (6-1) and an effluent collecting tank (6-2), the second crushed straw membrane component (6-1) is composed of at least 3 crushed straws, the pore diameters of the second crushed straw membrane component (6-1) are sequentially reduced along the water flow direction, and the formed pore diameter is smaller than that of the first crushed straw membrane component (1-3).

5. The system for treating domestic sewage through solar constant-temperature culture of microalgae according to claim 1, characterized in that: a sand discharge pipeline (1-2-1) is arranged at the bottom of a grit chamber (1-2) in the sewage inlet filter tank (1), so that the sediment at the bottom of the grit chamber (1-2) can be discharged in time; three filtering membranes are arranged in the first crushed straw membrane component (1-3), and the aperture of each filtering membrane is reduced along the water flow direction; a water distribution layer (1-4-4) is arranged in the quartz sand filter tank (1-4); a large-grain-size filter layer (1-4-1), a medium-grain-size filter layer (1-4-2) and a fine-grain-size filter layer (1-4-3) are arranged on a quartz sand filter tank (1-4), wherein the filter layer thickness of the large-grain-size filter layer (1-4-1) is 200-300mm, the grain size is 10-20mm, the filter layer thickness of the medium-grain-size filter layer (1-4-2) is 100-200mm, the grain size is 5-10mm, the filter layer thickness of the fine-grain-size filter layer (1-4-3) is 50-100mm, and the grain size is 1-5 mm; a back washing pipeline (1-4-5) is arranged at the bottom of the tank, and a gate valve (1-4-6) is arranged on a water outlet pipe of the sewage inlet filtering tank.

6. The system for treating domestic sewage through solar constant-temperature culture of microalgae according to claim 1, characterized in that: the water quantity regulating pool (3-2) in the microalgae culture pool (3) is provided with uniform water distribution holes, so that the sewage flowing through the water quantity regulating pool (3-2) can uniformly flow into the microalgae culture channel (3-3).

7. The system for treating domestic sewage through solar constant-temperature culture of microalgae according to claim 1, characterized in that: the sunlight greenhouse (2) with the sunlight plate is in a closed form, the top of the sunlight greenhouse (2) with the sunlight plate adopts a transparent sunlight plate (2-1), and the beam structure of the sunlight greenhouse (2) with the sunlight plate is provided with energy-saving LED lamps (2-4); the transmissivity of the transparent sunlight plate (2-1) is 20-80%, and the illumination intensity of the energy-saving LED lamp (2-4) is kept at 4000-8000 lux; the wall body (2-2) of the sunlight greenhouse of the sunlight plate is provided with vent holes (2-3).

8. The system for treating domestic sewage through solar constant-temperature culture of microalgae according to claim 1, characterized in that: the effluent filtering tank (6) is composed of a second crushed straw membrane component (6-1) and an effluent collecting tank (6-2), wherein at least three filtering membranes are arranged in the second crushed straw membrane component (6-1), and the aperture of each filtering membrane is sequentially reduced along the flowing water direction and is smaller than that of the crushed straw membrane component in the sewage inlet filtering tank; wherein the back flushing pipeline (1-4-5) and the water injection pipeline (3-1-1) of the water quality adjusting pool (3-1) are from the same main pipe of the water outlet collecting pool (6-2).