Tubular photo-biological reaction system and method for RO (Reverse Osmosis) concentrated water and flue gas treatment

Abstract

The invention discloses a tubular photo-biological reaction system and a tubular photo-biological reaction method for RO (Reverse Osmosis) concentrated water and flue gas treatment. According to the tubular photo-biological reaction system or method for RO concentrated water and flue gas treatment, provided by the invention, the RO concentrated water and flue gas CO2 can be synchronously treated by utilizing microalgae for treatment, and the dual purposes of efficient carbon sequestration and pollutant removal are achieved. The microalgae for treatment in the transparent reaction tube absorbs CO2 in the flue gas through photosynthesis under the action of illumination and converts the CO2 into biomass, so that the concentration of CO2 in the flue gas can be remarkably reduced; meanwhile, the microalgae for treatment can promote self growth by utilizing nutrient substances such as nitrogen and phosphorus in the strong brine, and harmful substances such as COD (Chemical Oxygen Demand), TN (Total Nitrogen) and TP (Total Phosphorus) in the strong brine are effectively degraded. By means of the synchronous treatment mode, CO2 emission is reduced, and a green and sustainable pollution treatment scheme can be provided for steel plants.

Description

Technical Field

[0001] The present invention relates to the field of environmental protection technologies, and particularly to a tubular photobioreactor system and method for treating RO concentrate and flue gas. Background Art

[0002] With the rapid development of the steel industry, the emissions of wastewater and waste gas have become important environmental protection issues that need to be urgently solved in this industry. During the production process of steel plants, a large amount of RO concentrate is generated. These concentrates usually contain high concentrations of pollutants such as nitrogen, phosphorus, calcium, magnesium, and chemical agents. If not properly treated, it will not only cause environmental pollution but also increase the cost of subsequent treatment. Traditional RO concentrate treatment technologies, such as advanced oxidation methods and evaporation crystallization, have problems of high cost, low efficiency, and possible secondary pollution. Therefore, it is crucial to develop a high-efficiency, economical, and green RO concentrate treatment technology.

[0003] Meanwhile, the steel industry has a huge CO2 emissions, making it an important object for emission reduction. Microalgae, as a highly efficient photosynthetic organism, can absorb nitrogen and phosphorus nutrients in water through photosynthesis, fix CO2, and convert it into biomass. This makes microalgae show great application potential in the fields of wastewater treatment and carbon emission reduction. Research shows that the addition of exogenous CO2 can significantly improve the growth rate of microalgae and enhance its ability to remove pollutants. However, existing research mainly focuses on the single treatment of wastewater and flue gas by microalgae, and rarely involves how to use microalgae for the synchronous treatment of wastewater and waste gas. Summary of the Invention

[0004] The purpose of the present invention is to provide a tubular photobioreactor system and method for treating RO concentrate and flue gas, so as to achieve the efficient removal of wastewater pollutants in RO concentrate and the effective reduction of CO2 in flue gas. By optimizing the growth conditions of microalgae, the present invention can reduce the treatment cost of RO concentrate and flue gas, and improve the resource recycling efficiency, providing a low-carbon and environmental protection comprehensive treatment solution for the treatment of RO concentrate and flue gas in the steel industry.

[0005] To achieve the above-mentioned invention purpose, the technical solution adopted by the present invention is as follows:

[0006] In the first aspect, the present invention provides a tubular photobioreactor system for treating RO concentrate and flue gas, and the tubular photobioreactor system includes:

[0007] A transparent reaction tube, provided with a reaction tube inlet and a reaction tube outlet; the transparent reaction tube is used for introducing a reaction liquid and flue gas, and the reaction liquid is a mixture of RO concentrate and microalgae for treatment;

[0008] The reaction liquid buffer device is provided with a circulating liquid outlet and a circulating liquid inlet. The circulating liquid inlet is communicated with the outlet of the reaction tube, and the circulating liquid outlet is communicated with the inlet of the reaction tube through a circulating pump. The reaction liquid buffer device is used to introduce reaction liquid into the transparent reaction tube and receive the reaction liquid from the transparent reaction tube.

[0009] The flue gas supply device is provided with a flue gas outlet, and the flue gas outlet can be communicated with the inlet of the reaction tube. The flue gas supply device is used to introduce flue gas into the transparent reaction tube.

[0010] The lighting device is used to provide light to the transparent reaction tube.

[0011] In an optional embodiment, the tubular photobioreactor system further includes:

[0012] The temperature monitoring device is used to monitor the temperature of the reaction liquid in the transparent reaction tube.

[0013] And / or, the pH monitoring device is used to monitor the pH value of the reaction liquid in the transparent reaction tube.

[0014] In an optional embodiment, the tubular photobioreactor system further includes:

[0015] The controller is electrically connected to at least the pH monitoring device and the flue gas supply device.

[0016] The controller can control the flue gas supply device to introduce flue gas into the transparent reaction tube when the pH monitoring device detects that the pH value of the reaction liquid in the transparent reaction tube is higher than the first preset pH value, or control the flue gas supply device to stop introducing flue gas into the transparent reaction tube when the pH monitoring device detects that the pH value of the reaction liquid in the transparent reaction tube is lower than the second preset pH value.

[0017] In a second aspect, the present invention provides a method for treating RO concentrated water and flue gas. The method includes the following steps:

[0018] Inoculate the microalgae for treatment into the RO concentrated water to obtain a reaction liquid.

[0019] Commonly introduce the reaction liquid and the flue gas into the transparent reaction tube, and provide light to the transparent reaction tube so that the microalgae for treatment synchronously treat the RO concentrated water and the flue gas.

[0020] In an optional embodiment, when introducing the flue gas into the transparent reaction tube, control the introduction amount of the flue gas so that the pH value of the reaction liquid in the transparent reaction tube is 6.5 - 7.5.

[0021] In an alternative embodiment, when the flue gas is introduced into the transparent reaction tube, the flow rate of the flue gas is 1 to 4 L / min;

[0022] and / or, the concentration of CO2 in the flue gas is 15% to 25%.

[0023] In an alternative embodiment, the conditions for the synchronous treatment include:

[0024] The treatment temperature is 20 to 35 °C;

[0025] and / or, the treatment time is 7 to 15 days;

[0026] and / or, the light intensity is 3000 to 10000 Lux.

[0027] In an alternative embodiment, the microalgae for the treatment are screened from the environment storing the RO concentrate, and the screening process includes:

[0028] Isolate multiple native algal strains from the environment storing the RO concentrate;

[0029] Screen out the algal strain with the strongest carbon fixation ability and the best adaptability from the multiple native algal strains as the microalgae for the treatment.

[0030] In an alternative embodiment, when the microalgae for the treatment are inoculated into the RO concentrate, the inoculation amount of the microalgae for the treatment is 0.01 to 0.05 g / L, or the OD of the reaction solution after inoculating the microalgae for the treatment 750 is 0.03 to 0.3.

[0031] In an alternative embodiment, after the synchronous treatment ends, the method further includes:

[0032] Recover 30% to 60% of the microalgae for the treatment in the reaction solution, and the remaining microalgae for the treatment continue to be used for the treatment of new RO concentrate of the same kind and flue gas.

[0033] The technical solution of the present invention has at least the following beneficial effects:

[0034] (1) It can achieve efficient carbon fixation and synchronous removal of pollutants.

[0035] The tubular photobioreactor system or method provided by the present invention for treating RO concentrated water and flue gas can simultaneously treat RO concentrated water and flue gas CO2 using treatment microalgae, achieving the dual goals of efficient carbon fixation and pollutant removal. The treatment microalgae in the transparent reaction tube absorb CO2 in the flue gas through photosynthesis under the action of light and convert it into biomass, which can significantly reduce the CO2 concentration in the flue gas. At the same time, the treatment microalgae can also utilize nutrients such as nitrogen and phosphorus in the concentrated salt water to promote their own growth and effectively degrade harmful substances such as COD, TN, and TP in the concentrated salt water. This synchronous treatment method not only reduces CO2 emissions but also provides a green and sustainable pollution treatment solution for steel plants.

[0036] (2) It can achieve energy conservation, emission reduction, and resource utilization.

[0037] The method provided by the present invention for treating RO concentrated water and flue gas significantly improves the carbon fixation efficiency and pollutant removal ability of microalgae by optimizing the algal strain culture conditions (such as temperature, light, CO2 concentration, etc.) and reactor operation parameters (such as flue gas flow rate, algal strain inoculation amount, etc.). Compared with traditional flue gas treatment technologies, the present invention uses microalgae for CO2 fixation without additional energy consumption, and the generated algal biomass can be further utilized as high-value-added products (such as biofuels, feeds, etc.), realizing the recycling of resources. In addition, by reducing the concentration of harmful substances in the concentrated salt water, the cost and difficulty of subsequent wastewater treatment are reduced. The application of the present invention not only helps steel plants achieve the "dual carbon" goal but also provides double benefits of economic and environmental benefits for them. Description of the Drawings

[0038] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0039] Figure 1 Schematically shows the structural diagram of a tubular photobioreactor system provided in an embodiment of the present invention;

[0040] Figure 2 Shows the temperature and pH changes of LJ3 under the introduction of RO concentrated water and flue gas CO2 in a steel plant in Example 2 of the present invention;

[0041] Figure 3 Shows the growth situation of LJ3 under the introduction of RO concentrated water and flue gas CO2 in a steel plant in Example 2 of the present invention;

[0042] Figure 4This is the nitrogen and phosphorus removal situation of LJ3 under the introduction of RO concentrated water from the steel plant and flue gas CO2 in Example 2 of the present invention.

[0043] Explanation of reference numerals:

[0044] 1. Transparent reaction tube; 2. Reaction liquid buffer device; 3. Flue gas supply device; 4. Circulation pump; 5. Controller. Detailed implementation manners

[0045] To further elaborate on the technical means and results adopted by the present invention to achieve the predetermined invention purpose, the following takes a preferred embodiment to detail the specific implementation manners, technical solutions and features according to the present invention as follows. The specific features, structures, or characteristics in the following descriptions of multiple embodiments can be combined in any suitable form.

[0046] For those steps or conditions not specified in the examples, the operations or conditions of the conventional experimental steps described in the literature in this field can be followed. For reagents or instruments not specified by the manufacturer, they are all conventional reagent products that can be obtained through commercial purchase.

[0047] The present invention provides a method for carbon fixation and emission reduction by using microalgae to synchronously treat RO concentrated brine from a steel plant and flue gas CO2, aiming to achieve the synchronous removal of CO2 fixation and pollutants (nitrogen and phosphorus, organic pollutants, metal ions, etc.) in the concentrated brine through the photosynthesis of microalgae, and achieve the dual goals of energy conservation, emission reduction and resource utilization.

[0048] The present invention provides a combined treatment method for using microalgae to synchronously treat RO concentrated water from a steel plant and CO2 waste gas. By introducing RO concentrated water and flue gas containing high-concentration CO2 into a transparent reaction tube and using the photosynthesis of microalgae, it is possible to remove pollutants such as nitrogen and phosphorus in the RO concentrated water and effectively fix the CO2 in the flue gas. This technology for synchronously treating wastewater and waste gas not only improves the recovery and utilization efficiency of resources, but also provides a new low-cost and environmentally friendly way for wastewater and waste gas treatment in the steel industry. The method specifically includes the following aspects:

[0049] (1) Isolation and screening of native algal strains

[0050] Isolate multiple (for example, 2 to 3 strains) native algal strains from places such as the RO concentrated water station, concentrated water storage tank, and discharge pipeline of the steel plant, and then screen out one dominant algal strain with the strongest carbon fixation ability and the best adaptability by comparing the carbon fixation ability, growth rate and pollutant tolerance of these native algal strains, and use it as the microalgae for treatment for the synchronous treatment of RO concentrated water and flue gas.

[0051] (2) Algal strain cultivation and flue gas carbon fixation

[0052] The selected dominant algal strains (microalgae for treatment) are inoculated into a medium containing RO concentrated water from a steel plant, and flue gas is introduced into the reactor for carbon fixation culture of the algal strains. The concentration of CO2 in the flue gas can be 15% to 25% (specifically subject to the actual CO2 concentration in the flue gas of the steel plant), including but not limited to 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, etc., and concentrations within this range are applicable.

[0053] (3) Optimization of culture conditions

[0054] Temperature control: During the culture process, the temperature of the medium is controlled at 20°C to 35°C, including 20°C, 22°C, 24°C, 26°C, 28°C, 30°C, 32°C, 34°C, 35°C, etc., and all temperatures within this range are applicable.

[0055] Light conditions: Provide a light intensity of 3000 to 10000 Lux (the light intensity can be controlled by a tubular photobioreactor system), and the light-dark cycle can be, for example, 12 hours of light: 12 hours of darkness (the light-dark ratio can be adjusted according to the actual environment of the steel plant) to promote the photosynthesis and growth of the algal strains.

[0056] Culture time: The carbon fixation culture time is usually 7 to 15 days, determined according to the remaining amount of nutrients in the RO concentrated water and the growth stage of the algal cells. When the remaining amount of nutrients is low or the algal cells enter the exponential growth phase, 30 - 60% of the algal cell mass can be recovered, and the remaining 40% - 70% of the algal liquid is re-inoculated into new concentrated brine for the next batch of culture. All recovery ratios within this range are applicable. The recovered algal cells are centrifuged for recycling.

[0057] (4) Reactor type and operation

[0058] A tubular photobioreactor is used for carbon fixation culture of the algal strains. This reactor can provide stable light and gas inflow to ensure the efficient growth of the algal strains and CO2 fixation.

[0059] (5) Synchronous treatment of RO concentrated water and flue gas CO2

[0060] During the carbon fixation culture process, the algal strains absorb CO2 in the flue gas through photosynthesis, and at the same time use nutrients (such as nitrogen, phosphorus, etc.) in the concentrated brine to promote their own growth, ultimately achieving the synchronous removal of CO2 in the flue gas and pollutants (such as organic pollutants like scale inhibitors and bacteriostatic agents) in the concentrated brine.

[0061] (6) Reactor operation parameters

[0062] Algal strain inoculation amount: The inoculation amount of the algal strains in the RO concentrated water is 0.01 to 0.05 g / L (or OD 750Reaching 0.03 - 0.3), specifically including 0.01 g / L, 0.02 g / L, 0.03 g / L, 0.04 g / L, 0.05 g / L, etc. All inoculation amounts within this range are applicable.

[0063] Flue gas flow control: The flow rate of the flue gas in the reactor is 1 to 4 L / min, specifically including 1 L / min, 2 L / min, 3 L / min, 4 L / min, etc.

[0064] pH control: The pH of the reaction solution is controlled by the tubular photobioreactor system and is set between 6.5 - 7.5. When the pH value of the reaction solution reaches 6.5, the flue gas is stopped from being introduced into the transparent reaction tube. When the pH value of the reaction solution exceeds 7.5, the flue gas continues to be introduced into the transparent reaction tube. By regulating the introduction of the flue gas based on the pH value of the reaction solution, the utilization rate of CO2 in the flue gas by microalgae can be significantly improved, thereby enhancing the removal efficiency of CO2 in the flue gas.

[0065] (7) Carbon sequestration effect

[0066] After culturing the algal strains, the algal strains with strong carbon sequestration ability can effectively absorb CO2 in the flue gas and simultaneously degrade harmful substances in the concentrated brine, achieving the dual goals of CO2 emission reduction and wastewater purification.

[0067] The following further describes the present invention in detail with specific embodiments, which should not be construed as limiting the scope claimed by the present invention.

[0068] Example 1

[0069] This example provides a tubular photobioreactor system for RO concentrated brine and flue gas treatment.

[0070] Figure 1 Schematically shows the structural schematic diagram of the tubular photobioreactor system of this example. As Figure 1 shown, the tubular photobioreactor system includes a transparent reaction tube 1, a reaction solution buffer device 2, a flue gas supply device 3, and a lighting device (not shown in the figure).

[0071] Among them, the transparent reaction tube 1 can be provided with a reaction tube inlet and a reaction tube outlet. The transparent reaction tube is used to introduce the reaction solution and the flue gas, and the reaction solution is a mixture of RO concentrated brine and microalgae for treatment. The material and shape of the transparent reaction tube can be selected within a certain range. For example, the material of the transparent reaction tube can be glass, specifically high borosilicate glass. The transparent reaction tube 1 can be composed of straight tubes and bent tubes. The straight tubes can be arranged in multiple rows and multiple layers, and the adjacent two rows of straight tubes or adjacent two layers of straight tubes are connected end to end through bent tubes, so that all the straight tubes and bent tubes form an integral body.

[0072] Exemplarily, the transparent reaction tube can be composed of 2 rows and 11 layers of straight tubes. The lower straight tubes in the front row and the upper straight tubes in the rear row are connected end to end through bent tubes, or the upper straight tubes in the front row and the lower straight tubes in the rear row are connected end to end through bent tubes, so that the transparent reaction tube is an integral pipeline with only one reaction tube inlet and one reaction tube outlet.

[0073] The reaction liquid buffer device 2 is provided with a circulating liquid outlet and a circulating liquid inlet. The circulating liquid inlet is communicated with the reaction tube outlet of the transparent reaction tube 1, and the circulating liquid outlet is communicated with the reaction tube inlet of the transparent reaction tube 1 through a circulating pump 4. The reaction liquid buffer device 2 is used to introduce the reaction liquid into the transparent reaction tube 1 and receive the reaction liquid from the transparent reaction tube 1.

[0074] The flue gas supply device 3 is provided with a flue gas outlet, and the flue gas outlet can be communicated with the reaction tube inlet of the transparent reaction tube 1. The flue gas supply device is used to introduce flue gas into the transparent reaction tube 1. The lighting device is used to provide light to the transparent reaction tube 1. The type of the lighting device can be selected within a certain range. Exemplarily, the lighting device can be a full-spectrum LED lamp.

[0075] In an optional implementation manner, the tubular photobioreactor system of this embodiment may further include a temperature monitoring device (not shown in the figure) and a pH monitoring device (not shown in the figure). Among them, the temperature monitoring device is used to monitor the temperature of the reaction liquid in the transparent reaction tube. The pH monitoring device is used to monitor the pH value of the reaction liquid in the transparent reaction tube.

[0076] In an optional implementation manner, the tubular photobioreactor system of this embodiment may further include a controller 5. The controller 5 is electrically connected to at least the above-mentioned pH monitoring device and the flue gas supply device 3. The controller 5 can control the flue gas supply device 3 to introduce flue gas into the transparent reaction tube 1 when the pH monitoring device detects that the pH value of the reaction liquid in the transparent reaction tube 1 is higher than the first preset pH value, or control the flue gas supply device 3 to stop introducing flue gas into the transparent reaction tube 1 when the pH monitoring device detects that the pH value of the reaction liquid in the transparent reaction tube 1 is lower than the second preset pH value.

[0077] In practical applications, in order to expand the equipment scale, the above-mentioned transparent reactor can be used as a reaction unit, and then a tubular photobioreactor system can be composed of several similar reaction units. Each reaction unit can operate independently, and the designed total breeding amount of each reaction unit reactor is 3m 3 , and the specific parameters are as follows:

[0078] (1) The total volume of each reaction unit is 3000L, the pipeline volume is 1200L, and it is assembled by high borosilicate glass tubes with an outer diameter of 75mm and a length of 2000mm;

[0079] (2) The glass pipelines are designed in two rows, each layer is connected by 8 straight glass pipes, with a total of 11 layers, and both ends are connected by U-shaped glass bent pipes;

[0080] (3) Controller: Set up a central control cabinet, which can display the breeding parameters such as temperature and pH in situ, automatically control the start and stop of the supplementary lighting system, and set the feedback control parameters;

[0081] (4) Power circulation system: Corrosion-resistant circulation pump, with a maximum head of 12m and a maximum flow rate of 15m 3 / h, and the flow rate is adjusted by a frequency converter;

[0082] (5) Automatic carbon supplementation system: Set the pH parameter range to achieve automatic carbon supplementation;

[0083] (6) Equipped with a 2000L buffer tank (reaction liquid buffer device), and there is an aeration device in the buffer tank;

[0084] (7) The whole is made of 304 stainless steel square pipes and assembled by on-site welding;

[0085] (8) The floor area is 10m × 1m;

[0086] (9) The working voltage is 380V.

[0087] Example 2

[0088] This example takes the actual wastewater and flue gas of a brine station of a steel plant in Linyi, Shandong, China as the research object, and simulates the synchronous treatment process of flue gas and brine. The CO2 concentration in the flue gas is 20%, and the main components of the brine are COD 148mg / L, TN 28.6mg / L, TP 1.85mg / L, pH is 8.3, and the temperature is 26°C.

[0089] This example provides a method for carbon fixation and emission reduction by synchronously treating the brine of a steel plant and flue gas CO2 using a native algal strain. The specific steps are as follows:

[0090] (1) Algal strain separation and screening:

[0091] Two native algal strains are separated from the brine station of the steel plant. By comparing their carbon fixation ability and growth rate, the algal strain with the strongest carbon fixation ability is selected as a strain of Desmodesmus subspicatus (hereinafter represented by LJ3), which is used as the microalgae for treatment and for subsequent experiments.

[0092] (2) Algal strain cultivation and flue gas carbon fixation:

[0093] The whole reaction is carried out in a tubular photobioreactor system of a steel plant in Linyi. LJ3 is inoculated into RO brine at an inoculation amount of OD 750 = 0.04, and to 3m 3In the tubular photobioreactor, flue gas is introduced at a flow rate of 2 L / min for carbon fixation cultivation.

[0094] (3) Cultivation conditions:

[0095] Temperature: The temperature of the RO concentrate is 26 °C, and the ambient temperature where the tubular reactor is located is 25 - 30 °C;

[0096] Light: The tubular reactor provides LED light with an intensity of 6000 Lux and a light - dark cycle of 12:12;

[0097] Cultivation time: The cultivation time in the first stage is 7 days until the algal cell concentration reaches a stable state. After 7 days, 60% of the algal cells are recovered, and the remaining 40% of the algal liquid is continuously inoculated with RO concentrate for cultivation. The recovered algal cells are centrifuged at 6000 g for 15 minutes, and the harvested algal cells are used for subsequent resource recovery.

[0098] (4) Reactor operation and parameter control:

[0099] Gas flow rate: The flue gas CO₂ inlet flow rate is 2 L / min;

[0100] pH regulation: Based on the pH value of the reaction solution, the introduction of flue gas is regulated. When the pH value of the reaction solution is lower than 6.5, the introduction of flue gas is stopped; when the pH value of the reaction solution is higher than 7.5, the flue gas is continuously introduced; when the pH value of the reaction solution is between 6.5 - 7.5, the flue gas is introduced for 5 seconds every 60 seconds to ensure efficient emission reduction of flue gas CO₂.

[0101] (5) Treatment effect evaluation:

[0102] After the cultivation is completed, the algal cell concentration, CO₂ fixation efficiency, and the removal rates of nitrogen and phosphorus in the RO concentrate are measured. In the tubular reactor, the changes in temperature and pH value show a relatively stable trend ( Figure 2 ). During the experiment, the temperature is maintained at 25.7 - 28.3 °C with a small fluctuation range, ensuring the stable progress of the reaction. Except for the initial inoculation of algae and the replacement of RO concentrate on the 8th day, the pH value is stable between 7.0 - 7.19, and the change range during the reaction process is small, basically maintaining within the set control range. The stability of temperature and pH is crucial for the continuity of the reaction process and the growth of microalgae.

[0103] Over time, the OD value of the reaction solution gradually increases ( Figure 3 ), indicating that the growth of microalgae is well - supported. In the initial stage of cultivation, the OD value is low, but after introducing RO concentrate and steel - mill flue gas CO₂, the photosynthesis of microalgae is promoted, and the OD value shows a stable upward trend, indicating the good adaptability of microalgae under these cultivation conditions. After the first batch of cultivation is completed, OD 750The value increased from 0.03 to 0.49; the OD of the second batch of cultivation after water replacement 750 reached 0.62.

[0104] In the tubular reactor, the removal of nitrogen and phosphorus showed significant effects. As the cultivation progressed, the concentrations of nitrogen (28.6 mg / L) and phosphorus (1.85 mg / L) in the reactor gradually decreased, indicating the effective absorption and removal of these nutrients by microalgae ( Figure 4 ). After a certain cultivation period, the maximum removal rates of nitrogen and phosphorus reached over 85% and 77% respectively, proving that microalgae can effectively remove nutrient salts in wastewater in this cultivation system, achieving the purpose of water purification.

[0105] In the tubular reactor, the carbon fixation rate gradually increased as the microalgae grew. By introducing the flue gas CO2 from the steel plant, microalgae can effectively absorb and convert the carbon dioxide therein. The carbon fixation rate showed a relatively rapid increase in the first few days, reaching a maximum of 70 mg / L / d, and then gradually stabilized, fluctuating between 30 mg / L / d and 45 mg / L / d. This demonstrated the good adaptability and carbon absorption ability of microalgae in a high-concentration CO2 environment, proving that microalgae can effectively reduce CO2 emissions while treating wastewater and have significant carbon fixation potential.

[0106] As described above, it is only the preferred specific embodiment of the present invention; however, the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution of the present invention and its improved concept, making equivalent substitutions or changes, should be covered by the protection scope of the present invention.

Claims

1. A tubular photobioreactor system for RO concentrated water and flue gas treatment, characterized in that, The tubular photobioreactor system includes: A transparent reaction tube, provided with a reaction tube inlet and a reaction tube outlet; the transparent reaction tube is used for introducing a reaction liquid and flue gas, and the reaction liquid is a mixture of RO concentrate and treatment microalgae; A reaction liquid buffer device, provided with a circulating liquid outlet and a circulating liquid inlet, the circulating liquid inlet is communicated with the reaction tube outlet, and the circulating liquid outlet is communicated with the reaction tube inlet through a circulating pump; the reaction liquid buffer device is used for introducing the reaction liquid into the transparent reaction tube and receiving the reaction liquid from the transparent reaction tube; A flue gas supply device, provided with a flue gas outlet, and the flue gas outlet can be communicated with the reaction tube inlet; the flue gas supply device is used for introducing flue gas into the transparent reaction tube; A lighting device, used for providing light to the transparent reaction tube.

2. The tubular photobioreactor system according to claim 1, wherein The tubular photobioreactor system further includes: A temperature monitoring device, used for monitoring the temperature of the reaction liquid in the transparent reaction tube; And / or, a pH monitoring device, used for monitoring the pH value of the reaction liquid in the transparent reaction tube.

3. The tubular photobioreactor system according to claim 2, wherein The tubular photobioreactor system further includes: A controller, electrically connected to at least the pH monitoring device and the flue gas supply device; The controller can control the flue gas supply device to introduce flue gas into the transparent reaction tube when the pH monitoring device detects that the pH value of the reaction liquid in the transparent reaction tube is higher than a first preset pH value, or control the flue gas supply device to stop introducing flue gas into the transparent reaction tube when the pH monitoring device detects that the pH value of the reaction liquid in the transparent reaction tube is lower than a second preset pH value.

4. A method for treating RO concentrated water and flue gas, characterized in that, The method includes the following steps: Inoculate the treatment microalgae into the RO concentrate to obtain a reaction liquid; Introduce the reaction liquid and flue gas into the transparent reaction tube together, and provide light to the transparent reaction tube so that the treatment microalgae synchronously treat the RO concentrate and the flue gas.

5. The method according to claim 4, characterized in that, When introducing the flue gas into the transparent reaction tube, control the introduction amount of the flue gas so that the pH value of the reaction liquid in the transparent reaction tube is 6.5 - 7.

5.

6. The method according to claim 5, wherein When introducing the flue gas into the transparent reaction tube, the flow rate of the flue gas is 1 - 4 L / min; And / or, the concentration of CO2 in the flue gas is 15% - 25%.

7. The method according to claim 4, wherein The conditions for the synchronous treatment include: The treatment temperature is 20 - 35 °C; And / or, the treatment time is 7 - 15 days; And / or, the light intensity is 3000 - 10000 Lux.

8. The method according to claim 4, wherein The treatment microalgae are screened from the environment storing the RO concentrate, and the screening process includes: Separate multiple native algal strains from the environment storing the RO concentrate; Screen out the algal strain with the strongest carbon fixation ability and the best adaptability from the multiple native algal strains as the treatment microalgae.

9. The method according to claim 4, wherein When inoculating the microalgae for treatment into the RO concentrate water, the inoculation amount of the microalgae for treatment is 0.01 - 0.05 g / L, or after inoculating the microalgae for treatment, the OD 750 of the reaction solution is 0.03 - 0.

3.

10. The method according to any one of claims 4 to 9, characterized in that, After the synchronous treatment ends, the method further includes: Recover 30 - 60% of the treatment microalgae in the reaction liquid, and the remaining treatment microalgae continue to be used for the treatment of new same-kind RO concentrate and flue gas.

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