CN107140719B - Method for strengthening algae coagulation by using nitrogen-doped titanium dioxide and simultaneously degrading algae-containing sediment under visible light - Google Patents
Method for strengthening algae coagulation by using nitrogen-doped titanium dioxide and simultaneously degrading algae-containing sediment under visible light Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
- C02F1/5236—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents
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- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
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Abstract
The invention discloses a method for strengthening algae coagulation and simultaneously degrading algae-containing bottom mud under visible light by using nitrogen-doped titanium dioxide, belonging to the field of drinking water treatment. The method comprises the following steps: (1): adding an algae removal coagulant into the algae-containing water, and stirring to complete coagulation; (2): after standing and precipitating, settling the algae-containing flocs to the bottom, and removing algae in the supernatant; (3): removing supernatant, retaining bottom sediment containing algae, irradiating under visible light, stirring, and degrading algae and algal toxin after a certain time. The invention can reduce the consumption of coagulant, enhance the coagulation effect, degrade algae and microcystin in the bottom sludge, and is suitable for treating high algae density water source and high algae density bottom sludge.
Description
Technical Field
The invention relates to the field of drinking water treatment, in particular to a nitrogen-doped titanium dioxide (N-TiO)2) A method for strengthening algae coagulation and simultaneously degrading algae-containing sediment under visible light.
Background
In recent years, the eutrophication phenomenon of freshwater lakes and reservoirs in China is increasingly serious, and algae are propagated in large quantities to form water bloom which seriously influences the quality of raw water. The large-scale propagation of the algae changes the physicochemical environment of the water body, reduces the transparency, smells fishy smell of the water body and reduces the dissolved oxygen, thereby not only influencing the ecological system, water supply, tourism and ecological landscape of the culture water area, but also seriously interfering the normal life of human beings.
In the drinking water process, algae removal relies primarily on a coagulation process. However, because the algae has certain floatability, the generated flocs are not easy to settle, thereby reducing the removal efficiency of the algae and increasing the burden of the subsequent treatment process. In addition, among the algal cells settled in the bottom sediment, there are some harmful algae such as microcystis aeruginosa (microcystis aeruginosa), which can release microcystin, affecting human health. When the muddy water containing the algal toxins is discharged, secondary pollution of the water body can be caused. Therefore, how to strengthen the algae coagulation, enhance the algae removal efficiency and effectively degrade the algae-containing bottom mud so as to discharge the mud water harmlessly is a problem which needs to be solved at present.
Disclosure of Invention
The invention aims to provide an algae removal method which can improve the efficiency of coagulation algae removal, degrade algae-containing bottom mud under visible light and discharge sludge water harmlessly.
In order to solve the technical problems, the invention provides the following technical scheme:
the invention provides a method for simultaneously treating algae in water and bottom sediment, which comprises the following steps:
step (1): adding an algae removal coagulant into the algae-containing water, and stirring to complete coagulation;
the algae removal coagulant consists of the following components in parts by weight: 50-400 parts by weight of N-TiO2Powder, 7.5 parts by weight of polyaluminum ferric chloride;
step (2): after standing and precipitating, settling the algae-containing flocs to the bottom, and removing algae in the supernatant;
and (3): removing supernatant, retaining bottom sediment containing algae, irradiating under visible light, stirring, and degrading algae and algal toxin after a certain time.
Wherein the N-TiO is2The powder is prepared by the following method: heating 12-18 parts by weight of butyl titanate, 18-22 parts by weight of absolute ethyl alcohol, 0.05-0.5 part by weight of urea and 28-35 parts by weight of dilute nitric acid solution at 80-100 ℃ for 3-5 hours, and calcining at 400-500 ℃ for 3-5 hours to obtain white powder, namely N-TiO2。
Wherein, the preparation method of the algae removal coagulant comprises the steps of weighing N-TiO according to the set weight parts2The powder and the polyaluminum ferric chloride are uniformly mixed to obtain the algae removal coagulant.
Compared with the prior art, the invention has the following beneficial effects:
in the invention, the algae removal coagulant adopts N-TiO2The powder and the polyaluminum ferric chloride are compounded, so that the using amount of the polyaluminum ferric chloride coagulant which is independently adopted is reduced by 50 percent, the using amount of the coagulant is obviously reduced, and the algae removal efficiency is enhanced. Furthermore, N-TiO2The powder has little influence on the environment, does not cause secondary pollution to the water body, reduces the content of heavy metal in the water body due to the reduction of the consumption of the coagulant, avoids heavy metal pollution and further improves the water quality. After the coagulation is finished, the N-TiO2The powder is settled into the sediment along with the algae-containing flocs, and the sediment containing algae is irradiated by visible light and stirred at the same time, so that all algae can be degraded and broken within 12hAnd the degradation rate of the algal toxin released by the algae within 48 hours reaches more than 85 percent. The amount of the bottom mud is reduced, and the water quality of the discharged mud water is improved, so that the discharged mud water can be safely discharged or further recycled.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.
FIG. 1 shows the effect of different doses of PAFC on algae removal.
FIG. 2 shows PAFC, PAFC and different concentrations of N-TiO2The algae removal rate of the powder compounded coagulant in the coagulation process.
FIG. 3 shows PAFC, PAFC and different concentrations of N-TiO2The algae removal rate of the coagulant compounded from the powder in the sedimentation process of flocs.
FIG. 4 shows different concentrations of N-TiO2The change of chlorophyll in the process of degrading the algae-containing bottom mud by the powder under visible light.
FIG. 5 shows different concentrations of N-TiO2The change of Microcystins (MCs) in the process of degrading the algae-containing bottom mud by the powder under visible light.
Detailed Description
It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of the stated features, steps, operations, and/or combinations thereof, unless the context clearly indicates otherwise.
The materials, reagents and the like used in the present invention are commercially available unless otherwise specified.
In the invention, the calculation formulas of the algae removal rate, the algae cell degradation rate and the Microcystin (MCs) degradation rate are as follows:
algae removal (%) (Experimental Water Source OD680Supernatant OD680) X 100%/water source OD for experiment680；
The algae cell degradation rate (%) - (0h containing algae bottom mud chlorophyll content-containing algae bottom mud chlorophyll content at the measured time point) × 100%/0 h containing algae bottom mud chlorophyll content;
the percent degradation rate of microcystin (microcystin content when the algae cells in the algae-containing bottom mud are completely broken-microcystin content in the algae-containing bottom mud at the measured time point) is multiplied by 100 percent/microcystin content when the algae cells in the algae-containing bottom mud are completely broken.
As described in the background art, the method for removing algae in the drinking water process has certain disadvantages, and harmful substances released by some algae cannot be effectively degraded, and in order to solve the technical problems, the invention provides a method for simultaneously treating algae in water and sediment, which comprises the following steps:
step (1): adding an algae removal coagulant into the algae-containing water, and stirring to complete coagulation;
the algae removal coagulant comprises the following components in parts by weight: 50-400 parts by weight of N-TiO2Powder, 7.5 parts by weight of polyaluminum ferric chloride;
step (2): after standing and precipitating, settling the algae-containing flocs to the bottom, and removing algae in the supernatant;
and (3): and (4) discarding the supernatant, keeping the bottom containing the algae bottom mud, placing under visible light for irradiation and stirring, and degrading algae and algal toxins after a certain time (12-48 hours).
In the step (1), in a preferred technical scheme of the invention, the algae removal coagulant is prepared from the following components in parts by weight: 200 to 250 parts by weight of N-TiO2Powder, 7.5 parts by weight of polyaluminum ferric chloride.
In the most preferred technical scheme of the invention, the algae removal coagulant isThe composition comprises the following components in parts by weight: 200 parts by weight of N-TiO2Powder, 7.5 parts by weight of polyaluminum ferric chloride.
Wherein the N-TiO is2The powder is prepared by the following method: heating 12-18 parts by weight of butyl titanate, 18-22 parts by weight of absolute ethyl alcohol, 0.05-0.5 part by weight of urea and 28-35 parts by weight of dilute nitric acid solution at 80-100 ℃ for 3-5 hours, and calcining at 400-500 ℃ for 3-5 hours to obtain white powder, namely N-TiO2。
In the preferred technical scheme of the invention, from the aspects of improving the algae removal rate and degrading the algae-containing bottom mud, the N-TiO2The powder is prepared by the following method:
adding 15 parts by weight of butyl titanate into 20 parts by weight of absolute ethyl alcohol, and stirring to obtain a solution A;
adding 0.05-0.5 part by weight of urea into 30 parts by weight of dilute nitric acid solution, and mixing to form a solution B;
slowly adding the solution A into the solution B under the stirring condition, adjusting the pH to 7 by using a sodium hydroxide solution, and heating for 3 hours at 80 ℃;
then centrifuging the system, removing the supernatant, washing the precipitate for 3 times, calcining the precipitate for 3 hours at 400-500 ℃ to obtain white powder, namely N-TiO2。
The N-TiO compound2The particle size of the powder is 50-150 meshes; more preferably, the N-TiO2The particle size of the powder was 100 mesh.
In the preferable technical scheme of the invention, the preparation method of the algae removal coagulant comprises the step of weighing N-TiO according to the set weight parts2The powder and the polyaluminum ferric chloride are uniformly mixed to obtain the algae removal coagulant.
Wherein in the step (1), the density of the algae-containing water is 105～107cells/mL, wherein the stirring condition is 150-250 rpm for 1-2 min, and 30-60 rpm for 10-20 min.
The dosage of the coagulant PAFC is 7.5mg/L (no N-TiO is added)2The optimal dosage of the compound is 15mg/L), N-TiO2The dosage is 50-400 mg/L. PAFC andN-TiO2the method is characterized in that the method is put into algae-containing water and quickly stirred to quickly disperse the algae-containing water to form fine alum flocs, the water body becomes more turbid at the moment, water flow can generate violent turbulence, the flocculation stage is a process that the alum flocs grow and become coarse, proper turbulence degree and enough retention time (10-20 min) are required, and a large amount of alum flocs can be observed to slowly sink depending on gravity in the later stage. The OD of the remaining supernatant (2 cm below the liquid surface) was measured during coagulation680And (4) inspecting the sedimentation condition of the flocs in the coagulation process.
In the step (2), the standing time is 10-60 min. A large amount of coarse alumen ustum is deposited in the sedimentation stage, the upper layer water is clear water, the rest alumen ustum with small particle size and small density gradually falls down and continuously collides with each other to be larger, and the remaining turbidity is basically unchanged in the later stage. Determination of OD of supernatant turbidity during sedimentation680The time required for the flocs to settle completely was examined.
Usually, the algae cells in the water body have the characteristics of large quantity, small specific gravity, higher negative charge on the surface and the like, so that the algae cells are difficult to remove. In addition, the floc formed by the algae cells has certain floatability, so that the floc is difficult to settle, and the algae removal efficiency is reduced. The polyaluminum ferric chloride is an efficient inorganic high-molecular coagulant, and when a proper amount of N-TiO is added in the coagulation process2In powder form, N-TiO2Can be used as the core of micro floccules generated by the destabilization of a coagulant, and is matched with polyaluminium ferric chloride to ensure that coagulated algae cells form alum floc quickly and have high settling speed and good algae removal effect by utilizing the precipitate net-trapping mechanism, the electric neutralization and the bridging action.
In the step (3), the volume of the discarded supernatant accounts for 93-97% of the total volume, the illumination intensity is 3000-15000 Lux, and the stirring speed is 200-800 rpm.
TiO2The semiconductor is the most widely used photocatalyst due to its advantages of non-toxicity, low cost, stable performance and corrosion resistance. However, titanium dioxide photocatalysts also have some limitations in terms of their photocatalytic efficiency: the forbidden band width is 3.2eV, the light absorption waveband is narrow (mainly in an ultraviolet region), and the sunlight utilization efficiency is low; high recombination rate of semiconductor carriers, low quantum efficiency, and the like. WhileThe introduction of non-metal element N can enlarge TiO2The light response range, thereby improving the photocatalytic activity in the visible light region. Thus, N-TiO2Can efficiently degrade algae, algal toxins and intracellular and extracellular organic matters under visible light.
When the initial algae concentration is 105～107cell/mL, N-TiO2The adding amount of the powder is 50-400 mg/L, and the mixed adding amount of the polyaluminium ferric chloride is 7.5mg/L (no N-TiO is added)2The optimal dosage of the algae removal agent is 15mg/L), the algae removal rate can reach over 96 percent, and the algae removal rate is good. In the process of degrading the algae-containing bottom mud, the algae are completely degraded and broken within 12 hours, and the degradation rate of the algal toxin released by the algae reaches more than 85 percent within 48 hours.
In order to make the technical solution of the present invention more clearly understood by those skilled in the art, the technical solution of the present invention will be described in detail below with reference to specific examples and comparative examples.
Example 1
The algae removal coagulant consists of the following components in parts by weight: 50 parts by weight of N-TiO2Powder (particle size 100 mesh) and 7.5 parts by weight of polyaluminum ferric chloride.
Microcystis aeruginosa (Microcysticeruginosa) used in the experiment is cultured by adopting BG11 culture medium, the temperature is 25 ℃, the illumination is 12 hours, the darkness is 12 hours, the illumination intensity is 2000lux, and the microcystis aeruginosa is cultured to a logarithmic growth stage and is used for preparing the algae-containing water source for the experiment.
Diluting the algae solution to 1 × 10 with deionized water6cells/mL, preparing a water source for experiments, treating a water sample with the volume of 1L, and weighing N-TiO250mg of powder and 7.5mg of polyaluminum ferric chloride are mixed and added into each liter of experimental water source, fast stirring is carried out at 250rpm for 1min, and slow stirring is carried out at 30rpm for 30min, thus completing the coagulation process. Collecting supernatant at two cm below the liquid surface in the coagulation process and 2 hr after coagulation, and detecting its absorbance (OD) at 680nm wavelength680) The algae removal rate reached a maximum of 96% 1h after completion of coagulation. See fig. 2 and 3.
After the algal floc is settled, the supernatant is discarded, and the rest part is the algal bottom mud which accounts for about 7 percent of the original volume. The sediment containing algae is placed under 8000lux of visible light and stirred at 500rpm, after 48h, 41.6% of algae cells are degraded, and part of microcystins are still present in the algae cells. See fig. 4 and 5.
Example 2
The algae removal coagulant consists of the following components in parts by weight: 100 parts by weight of N-TiO2Powder (particle size 100 mesh) and 7.5 parts by weight of polyaluminum ferric chloride.
Microcystis aeruginosa (Microcysticeruginosa) used in the experiment is cultured by adopting BG11 culture medium, the temperature is 25 ℃, the illumination is 12 hours, the darkness is 12 hours, the illumination intensity is 2000lux, and the microcystis aeruginosa is cultured to a logarithmic growth stage and is used for preparing the algae-containing water source for the experiment.
Diluting the algae solution to 1 × 10 with deionized water6cells/mL, preparing a water source for experiments, treating a water sample with the volume of 1L, and weighing N-TiO2100mg of the powder and 7.5mg of the polyaluminum ferric chloride are mixed and added into each liter of experimental water source, the mixture is quickly stirred at 250rpm for 1min, and is slowly stirred at 30rpm for 30min to complete the coagulation process. Collecting supernatant at two cm below the liquid surface in the coagulation process and 2 hr after coagulation, and detecting its absorbance (OD) at 680nm wavelength680) The algae removal rate reached a maximum of 97% 1h after completion of coagulation. See fig. 2 and 3.
After the algal floc is settled, the supernatant is discarded, and the rest part is the algal bottom mud which accounts for about 7 percent of the original volume. The sediment containing algae is placed under 8000lux of visible light and stirred at 500rpm, after 48h, 59.9% of algae cells are degraded, and part of microcystins are still present in the algae cells. See fig. 4 and 5.
Example 3
The algae removal coagulant consists of the following components in parts by weight: 200 parts by weight of N-TiO2Powder (particle size 100 mesh) and 7.5 parts by weight of polyaluminum ferric chloride.
Microcystis aeruginosa (Microcysticeruginosa) used in the experiment is cultured by adopting BG11 culture medium, the temperature is 25 ℃, the illumination is 12 hours, the darkness is 12 hours, the illumination intensity is 2000lux, and the microcystis aeruginosa is cultured to a logarithmic growth stage and is used for preparing the algae-containing water source for the experiment.
Use awayDiluting the algae solution to 1 × 10 with ionized water6cells/mL, preparing a water source for experiments, treating a water sample with the volume of 1L, and weighing N-TiO2200mg of powder and 7.5mg of polyaluminum ferric chloride are mixed and added into each liter of experimental water source, fast stirring is carried out at 250rpm for 1min, and slow stirring is carried out at 30rpm for 30min to complete the coagulation process. Collecting supernatant at two cm below the liquid surface in the coagulation process and 2 hr after coagulation, and detecting its absorbance (OD) at 680nm wavelength680) The algae removal rate reached a maximum value of 98% 10min after completion of coagulation. See fig. 2 and 3.
After the algal floc is settled, the supernatant is discarded, and the rest part is the algal bottom mud which accounts for about 7 percent of the original volume. The sediment containing algae is placed under 8000lux of visible light to be irradiated and stirred at the rotating speed of 500rpm, after 12 hours, all algae cells are degraded, and after 48 hours, the degradation rate of microcystins is 84.2%. See fig. 4 and 5.
Example 4
The algae removal coagulant consists of the following components in parts by weight: 400 parts by weight of N-TiO2Powder (particle size 100 mesh) and 7.5 parts by weight of polyaluminum ferric chloride.
Microcystis aeruginosa (Microcysticeruginosa) used in the experiment is cultured by adopting BG11 culture medium, the temperature is 25 ℃, the illumination is 12 hours, the darkness is 12 hours, the illumination intensity is 2000lux, and the microcystis aeruginosa is cultured to a logarithmic growth stage and is used for preparing the algae-containing water source for the experiment.
Diluting the algae solution to 1 × 10 with deionized water6cells/mL, preparing a water source for experiments, treating a water sample with the volume of 1L, and weighing N-TiO2400mg of the powder and 7.5mg of the polyaluminum ferric chloride are mixed and added into each liter of experimental water source, the mixture is quickly stirred at 250rpm for 1min, and is slowly stirred at 30rpm for 30min to complete the coagulation process. Collecting supernatant at two cm below the liquid surface in the coagulation process and 2 hr after coagulation, and detecting its absorbance (OD) at 680nm wavelength680) The algae removal rate reached a maximum value of 98% 10min after completion of coagulation. See fig. 2 and 3.
After the algal floc is settled, the supernatant is discarded, and the rest part is the algal bottom mud which accounts for about 7 percent of the original volume. The sediment containing algae is placed under 8000lux of visible light to be irradiated and stirred at the rotating speed of 500rpm, after 12 hours, all algae cells are degraded, and after 48 hours, the degradation rate of the microcystins is 87.6 percent. See fig. 4 and 5.
In examples 1 to 4, the algaecide coagulant in example 3 is preferred. In examples 1 and 2, the algae in the substrate sludge are not completely degraded within 48 hours, and the treatment effect is not achieved. In example 4, N-TiO2The addition of the powder is too large, and part of the powder remains in the supernatant after coagulation is completed, so that the water quality is affected and the treatment cost is increased.
In the face of the technical problems of how to strengthen the coagulation of algae, enhance the efficiency of removing algae, reduce the dosage of conventional coagulants and effectively degrade the algae-containing bottom mud, the invention adopts the basic idea of strengthening the coagulation of algae and degrading the algae-containing bottom mud under visible light by mutually matching the photocatalyst and the conventional coagulants, and screens and optimizes the raw materials and the proportion content of the raw materials under the idea. For the type of photocatalyst, the inventor selects and optimizes the nitrogen-doped titanium dioxide photocatalyst, because research finds that compared with other metal or nonmetal-doped TiO2，TiO2After nitrogen doping, the charge balance of the titanium dioxide material is damaged to a certain extent, and according to the characteristics, the titanium dioxide material can be used as the core of a micro floccule generated by the destabilization of a coagulant, and is matched with polyaluminium chloride to be beneficial to the dispersion of the coagulant and the formation of the floccule, so that the flocculation effect is enhanced, and the phenomenon of alumen ustum floating in a short time can be solved; in addition, nitrogen-doped TiO2Degrading algae, algal toxins and intracellular and extracellular organic matters under visible light. For the screening of the coagulant and aiming at the characteristics of algae, polyaluminum ferric chloride is preferably selected, which integrates the advantages of aluminum salt and ferric salt, obviously improves the forms of aluminum ions and ferric ions, and greatly improves the polymerization degree; TiO doped with nitrogen2The maximum effect of treating the algae-containing water body is exerted by mutual matching; while for the choice of the amount, it is preferably 7.5 parts by weight of polyaluminum ferric chloride, as N-TiO2The using amount is certain (the best treatment effect and the lowest using amount are achieved), and when the using amount is more than 7.5 parts by weight of polyaluminum ferric chloride, the algae removal rate is reduced; when less than 7.5 parts by weight of polyaluminum ferric chloride, no matter the content of N-TiO2The treatment effect cannot be optimal due to the use amount of the poly aluminum ferric chloride, and 7.5 parts by weight of poly aluminum ferric chloride and 50-400 parts by weight of N-TiO are selected in consideration of the comprehensive consideration2And (3) powder.
When the effects of various raw materials and raw material proportions on the treatment of the algae-containing water body are researched, the results show that different raw material combinations have obvious differences on the effects on the treatment of the algae-containing water body, and only comparative examples 1 to 5 are taken as examples, but the research is not limited to the following comparative examples.
Comparative example 1
The algae removal coagulant consists of the following components in parts by weight: 7.5 parts by weight of polyaluminum ferric chloride.
Microcystis aeruginosa (Microcysticeruginosa) used in the experiment is cultured by adopting BG11 culture medium, the temperature is 25 ℃, the illumination is 12 hours, the darkness is 12 hours, the illumination intensity is 2000lux, and the microcystis aeruginosa is cultured to a logarithmic growth stage and is used for preparing the algae-containing water source for the experiment.
Diluting the algae solution to 1 × 10 with deionized water6cells/mL, preparing a water source for experiments, weighing 7.5mg of polymeric aluminum ferric chloride, mixing and adding into each liter of experimental water source, quickly stirring at 250rpm for 1min, and slowly stirring at 30rpm for 30min to complete the coagulation process, wherein the volume of the treated water sample is 1L. Collecting supernatant at two cm below the liquid surface in the coagulation process and 2 hr after coagulation, and detecting its absorbance (OD) at 680nm wavelength680) The removal rate of algae is shown in fig. 2 and fig. 3, and can be obtained from fig. 2, the flocculation speed is low, the removal rate of algae in the coagulation process is low and is only 5-6%, and can be obtained from fig. 3, the removal rate of algae is only about 60% in 30min during the sedimentation process of flocs, and the removal rate of algae reaches the maximum value only 80% in 120 min.
After the algal floc is settled, the supernatant is discarded, and the rest part is the algal bottom mud which accounts for about 7 percent of the original volume. The algae-containing substrate sludge is placed under 8000lux of visible light and stirred at the rotating speed of 500rpm, the degradation rate of algae cells is shown in figure 4, the change of microcystins is shown in figure 5, and the content of chlorophyll and microcystins is not changed greatly.
The effect of removing algae by using PAFC alone is shown in FIG. 1, and it can be seen from FIG. 1 that the algae removal rate is only about 60% when the PAFC dose is 7.5mg/L, and the algae removal rate is at maximum 90% when the PAFC dose is 15 mg/L.
Comparative example 2
The algae removal coagulant consists of the following components in parts by weight: 200 parts by weight of N-TiO2Powder (particle size 100 mesh) and 7.5 parts by weight of polyaluminum ferric silicate.
Microcystis aeruginosa (Microcysticeruginosa) used in the experiment is cultured by adopting BG11 culture medium, the temperature is 25 ℃, the illumination is 12 hours, the darkness is 12 hours, the illumination intensity is 2000lux, and the microcystis aeruginosa is cultured to a logarithmic growth stage and is used for preparing the algae-containing water source for the experiment.
Diluting the algae solution to 1 × 10 with deionized water6cells/mL, preparing a water source for experiments, treating a water sample with the volume of 1L, and weighing N-TiO2200mg of powder and 7.5mg of polyaluminum ferric chloride are mixed and added into each liter of experimental water source, fast stirring is carried out at 250rpm for 1min, and slow stirring is carried out at 30rpm for 30min to complete the coagulation process. Collecting supernatant at two cm below the liquid surface in the coagulation process and 2 hr after coagulation, and detecting its absorbance (OD) at 680nm wavelength680). In the sedimentation process of the flocs, the algae removal rate can reach 80 percent at 30 min.
Comparative example 3
The algae removal coagulant consists of the following components in parts by weight: 200 parts by weight of TiO2Powder (particle size 100 mesh) and 7.5 parts by weight of polyaluminum ferric chloride.
Microcystis aeruginosa (Microcysticeruginosa) used in the experiment is cultured by adopting BG11 culture medium, the temperature is 25 ℃, the illumination is 12 hours, the darkness is 12 hours, the illumination intensity is 2000lux, and the microcystis aeruginosa is cultured to a logarithmic growth stage and is used for preparing the algae-containing water source for the experiment.
Diluting the algae solution to 1 × 10 with deionized water6cells/mL, preparing a water source for experiments, treating a water sample with the volume of 1L, and weighing N-TiO2200mg of powder and 7.5mg of polyaluminum ferric chloride are mixed and added into each liter of experimental water source, fast stirring is carried out at 250rpm for 1min, and slow stirring is carried out at 30rpm for 30min to complete the coagulation process. Collecting supernatant at two cm below the liquid surface in the coagulation process and 2 hr after coagulation, and detecting its absorbance (OD) at 680nm wavelength680)。In the sedimentation process of the flocs, the algae removal rate can reach 85 percent in 30 min.
After the algal floc is settled, the supernatant is discarded, and the rest part is the algal bottom mud which accounts for about 7 percent of the original volume. The algal containing sediment was placed under 8000lux of visible light while stirring at 500 rpm. After 48 hours, only 49 percent of algae cells are degraded, and the degradation rate of the microcystins after 48 hours is only 48.4 percent.
Comparative example 4
The algae removal coagulant consists of the following components in parts by weight: 200 parts by weight of rare earth doped TiO2Powder (particle size 100 mesh) and 7.5 parts by weight of polyaluminum ferric silicate.
Wherein, the rare earth is doped with TiO2The powder is prepared by the following method:
taking 20ml of absolute ethyl alcohol, then adding butyl titanate, stirring for 2h, adding a rare earth lanthanum nitrate solution for hydrolysis, continuing to stir strongly until gel is generated, taking out and drying, and roasting in a 400 ℃ muffle furnace for 5h to obtain rare earth doped TiO2And (3) powder.
Microcystis aeruginosa (Microcysticeruginosa) used in the experiment is cultured by adopting BG11 culture medium, the temperature is 25 ℃, the illumination is 12 hours, the darkness is 12 hours, the illumination intensity is 2000lux, and the microcystis aeruginosa is cultured to a logarithmic growth stage and is used for preparing the algae-containing water source for the experiment.
Diluting the algae solution to 1 × 10 with deionized water6cells/mL, preparing a water source for experiments, treating a water sample with the volume of 1L, and weighing N-TiO2200mg of powder and 7.5mg of polyaluminum ferric chloride are mixed and added into each liter of experimental water source, fast stirring is carried out at 250rpm for 1min, and slow stirring is carried out at 30rpm for 30min to complete the coagulation process. Collecting supernatant at two cm below the liquid surface in the coagulation process and 2 hr after coagulation, and detecting its absorbance (OD) at 680nm wavelength680). In the sedimentation process of the flocs, the algae removal rate can reach 83 percent at 30 min.
After the algal floc is settled, the supernatant is discarded, and the rest part is the algal bottom mud which accounts for about 7 percent of the original volume. The algal containing sediment was placed under 8000lux of visible light while stirring at 500 rpm. After 48 hours, only 43 percent of algae cells are degraded, and the degradation rate of the microcystins after 48 hours is only 45.6 percent.
Comparative example 5
The algae removal coagulant consists of the following components in parts by weight: 200 parts by weight of N-TiO2Powder (particle size 100 mesh) and 10 parts by weight of polyaluminum ferric chloride.
Microcystis aeruginosa (Microcysticeruginosa) used in the experiment is cultured by adopting BG11 culture medium, the temperature is 25 ℃, the illumination is 12 hours, the darkness is 12 hours, the illumination intensity is 2000lux, and the microcystis aeruginosa is cultured to a logarithmic growth stage and is used for preparing the algae-containing water source for the experiment.
Diluting the algae solution to 1 × 10 with deionized water6cells/mL, preparing a water source for experiments, treating a water sample with the volume of 1L, and weighing N-TiO2200mg of powder and 7.5mg of polyaluminum ferric chloride are mixed and added into each liter of experimental water source, fast stirring is carried out at 250rpm for 1min, and slow stirring is carried out at 30rpm for 30min to complete the coagulation process. Collecting supernatant at two cm below the liquid surface in the coagulation process and 2 hr after coagulation, and detecting its absorbance (OD) at 680nm wavelength680). In the sedimentation process of the flocs, the algae removal rate can reach 90 percent in 30 min.
In conclusion, the algae removal coagulant provided by the invention adopts PAFC and N-TiO2Compared with a single coagulant or other coagulants, the dosage of the coagulant is reduced by 50 percent, the water treatment cost is obviously reduced, the algae removal efficiency is more than 96 percent, the effect is obviously higher than that of comparative examples 1-5, wherein N-TiO2The powder has little influence on the environment and can not cause secondary pollution to water. After the coagulation is finished, the N-TiO2Settling the powder with the algae-containing floc into the sediment, irradiating the sediment with visible light while stirring, adding appropriate amount of N-TiO2Under the dosage, all the algae can be degraded and broken within 12 hours, the degradation rate of the algal toxin released by the algae within 48 hours reaches more than 85%, and the effect is obviously higher than that of comparative examples 1-5. The amount of the bottom mud is reduced, and the water quality of the discharged mud water is improved, so that the discharged mud water can be safely discharged or further recycled. In addition, the dosage of each component in the algae removal coagulant is very critical, and the inventor adjusts the dosage of the raw materials in the test process, and finds that the dosage of the raw materials is adjustedThe algae removal rate of the algae removal coagulant and the effect of degrading the algae-containing sediment are obviously reduced.
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.
Claims (2)
1. A method for simultaneously treating algae in water and bottom sediment is characterized by comprising the following steps:
step (1): adding an algae removal coagulant into the algae-containing water, and stirring to complete coagulation;
the algae removal coagulant consists of the following components in parts by weight: 200 parts by weight of N-TiO2Powder, 7.5 parts by weight of polyaluminum ferric chloride; the N-TiO compound2The particle size of the powder is 100 meshes;
step (2): after standing and precipitating, settling the algae-containing flocs to the bottom, and removing algae in the supernatant;
and (3): removing supernatant, keeping bottom sediment containing algae, irradiating under visible light, stirring, and degrading algae and algal toxin after a certain time;
wherein, the N-TiO in the step (1)2The powder is prepared by the following method: heating 12-18 parts by weight of butyl titanate, 18-22 parts by weight of absolute ethyl alcohol, 0.05-0.5 part by weight of urea and 28-35 parts by weight of dilute nitric acid solution at 80-100 ℃ for 3-5 hours, and calcining at 400-500 ℃ for 3-5 hours to obtain white powder, namely N-TiO2；
In the step (1), the density of the algae-containing water is 105~107cells/mL, wherein the stirring condition is that stirring is carried out at 150-250 rpm for 1-2 min, and stirring is carried out at 30-60 rpm for 10-20 min;
in the step (1), the concentration of polyaluminum ferric chloride contained in the algae-containing water is 7.5 mg/L; N-TiO contained in algae-containing water2The concentration of (A) is 200 mg/L;
in the step (2), standing for 10-60 min;
in the step (3), the volume of the discarded supernatant accounts for 93-97% of the total volume, the illumination intensity is 3000-15000 Lux, and the stirring speed is 200-800 rpm.
2. The method for simultaneously treating the algae in the water body and the sediment according to claim 1, wherein in the step (1), the preparation method of the algae removal coagulant comprises the following steps: weighing N-TiO according to the set weight parts2The powder and the polyaluminum ferric chloride are uniformly mixed to obtain the algae removal coagulant.
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| CN201710352078.3A CN107140719B (en) | 2017-05-18 | 2017-05-18 | Method for strengthening algae coagulation by using nitrogen-doped titanium dioxide and simultaneously degrading algae-containing sediment under visible light |
| AU2017414238A AU2017414238B2 (en) | 2017-05-18 | 2017-09-29 | Method for enhancing algae coagulation using nitrogen-doped titanium dioxide and degrading algae-containing sediment in visible light simultaneously |
| PCT/CN2017/104482 WO2018209874A1 (en) | 2017-05-18 | 2017-09-29 | Method for enhancing algae coagulation using nitrogen-doped titanium dioxide and degrading algae-containing sediment in visible light simultaneously |
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| CN107140719B (en) * | 2017-05-18 | 2020-05-08 | 山东大学 | Method for strengthening algae coagulation by using nitrogen-doped titanium dioxide and simultaneously degrading algae-containing sediment under visible light |
| CN107098453B (en) * | 2017-05-18 | 2020-05-12 | 山东大学 | Algae removal coagulant for strengthening algae coagulation and simultaneously degrading algae-containing sediment under visible light, and preparation method and application thereof |
| CN107570197A (en) * | 2017-10-11 | 2018-01-12 | 南开大学 | A kind of synthetic method of hollow auto-dope structure bimetallic photochemical catalyst and application |
| CN107935269B (en) * | 2017-12-21 | 2020-05-12 | 山东大学 | Water treatment process capable of recycling coagulant and photocatalytic material and realizing zero discharge of muddy water |
| CN108147496B (en) * | 2017-12-21 | 2020-06-05 | 山东大学 | Method for degrading water pollutants by using nano photocatalyst flocs |
| CN110354833B (en) * | 2019-06-18 | 2022-12-23 | 中冶华天工程技术有限公司 | Method for preparing visible light response mesoporous titanium dioxide material by utilizing coagulated sludge |
| CN113511712A (en) * | 2021-05-25 | 2021-10-19 | 中国人民解放军陆军勤务学院 | Application of titanium trichloride and treatment method of high algae-laden water containing copper green microcystis |
| CN114890524B (en) * | 2022-04-18 | 2023-07-25 | 武汉理工大学三亚科教创新园 | Algae removing agent based on amphiphilic dendrimer and algae removing method thereof |
| CN114956412A (en) * | 2022-07-08 | 2022-08-30 | 天津农学院 | Catalytic treatment process for microcystin in aquaculture tail water |
| CN117494290A (en) * | 2023-12-29 | 2024-02-02 | 深圳市大鹏园林生态建设有限公司 | Ecological garden greening optimization method |
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| JP2004249148A (en) * | 2003-02-18 | 2004-09-09 | Touzai Kagaku Sangyo Kk | Algicidal method for cleaned water tank |
| KR100836527B1 (en) * | 2008-01-31 | 2008-06-10 | (주) 존인피니티 | Composition for removing red algae, green algae or diatom using porous nano sized titania photocatalyst, manufacturing method of said composition and red algae, green algae or diatom removing method using said composition |
| WO2010022394A2 (en) * | 2008-08-22 | 2010-02-25 | The Board Of Trustees Of The University Of Illinois | Catalytic compositions, composition production methods, and aqueous solution treatment methods |
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| CN105776688A (en) * | 2016-03-29 | 2016-07-20 | 刘牧 | Treatment method of algae-laden water or high-concentration organic waste water |
| CN106186231A (en) * | 2016-08-15 | 2016-12-07 | 山东大学 | Except algae coagulant and preparation thereof and algae-removing method |
| CN107140719B (en) * | 2017-05-18 | 2020-05-08 | 山东大学 | Method for strengthening algae coagulation by using nitrogen-doped titanium dioxide and simultaneously degrading algae-containing sediment under visible light |
| CN107098453B (en) * | 2017-05-18 | 2020-05-12 | 山东大学 | Algae removal coagulant for strengthening algae coagulation and simultaneously degrading algae-containing sediment under visible light, and preparation method and application thereof |
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