CN110642472A - Mixed flocculant and method for treating cyanobacteria blooms therewith - Google Patents

Abstract

The invention discloses a mixed flocculant and a method for treating cyanobacteria blooms by using the mixed flocculant. , talc and diatomaceous earth are mixed; the steps of controlling cyanobacterial blooms with mixed flocculants are as follows: Step 1, after weighing each raw material according to the mass ratio and mixing, place it in an electronic stirrer to stir and let stand to obtain mixed flocculation Step 2, put the mixed flocculant into the water body evenly, stir and disperse, and use a fishing net with a diameter of 0.149mm to salvage the cyanobacterial mud after flocculation for 6 hours; Step 3, mix the cyanobacterial mud, activated sludge and water in a volume ratio of 1:1 : 1 is placed in an anaerobic fermentation device, fermented for 90 days at 20.2 ° C and a pH value of 8.3, and the plants are irrigated with fermentation broth for secondary utilization; the mixed flocculant of the present invention has low cost and good flocculation effect. The treatment of cyanobacterial blooms is simple and thorough.

Description

Mixed flocculant and method for treating cyanobacteria blooms therewith

technical field

The invention belongs to the technical field of water pollution treatment, in particular to a mixed flocculant and a method for treating cyanobacteria blooms therewith.

Background technique

The surface layer of eutrophic water body is dense with algae, and blue-green algae bloom consumes a lot of dissolved oxygen in the water body, making it difficult for sunlight to penetrate into the deep water body, and the dissolved oxygen at the bottom of the lake decreases. , consume the dissolved oxygen in the deep water, and in severe cases, the dissolved oxygen in the deep water can be exhausted and become an anaerobic state. This anaerobic state can trigger or accelerate the accumulation of sediment in the water body and the release of nutrients, resulting in a high load of nutrients in the water body. , forming a vicious circle of eutrophic water bodies.

The growth of cyanobacterial blooms causes the disappearance of aquatic vegetation, the suffocation and death of a large number of fish, and the sharp reduction of species. The structure is destroyed, the material circulation and energy flow in the water ecosystem are blocked, and the balance of the entire water ecosystem is eventually destroyed.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a mixed flocculant, the clay flocculant is mixed for use, the flocculation effect of the flocculant is improved, and the cost of the mixed flocculant is low and economically feasible.

The purpose of the present invention is also to provide a method for controlling cyanobacterial blooms by using a mixed flocculant. The treatment process is simple and easy to operate, and the cyanobacterial blooms are flocculated and salvaged thoroughly, which can effectively curb the eutrophication of water bodies and restore the balance of water body ecosystems.

The technical scheme adopted in the present invention is that the mixed flocculant is prepared by mixing third-grade sepiolite wool, talc and diatomite with a mass ratio of (1-4):(3-12):(2-8).

Further, the mass ratio of tertiary sepiolite wool, talc and diatomaceous earth is 1:12:8.

The method for mixing flocculants to control cyanobacterial blooms specifically includes the following steps:

Step 1: Weigh the third-grade sepiolite wool, talc and diatomite according to the mass ratio, mix the raw materials, place them in an electronic stirrer, stir for 5 min, let stand for 1 h, repeat stirring and let stand three times to obtain a mixed flocculant;

In step 2, the mixed flocculant is evenly put into the water body, stirred and dispersed, and after flocculation for 6 hours, the cyanobacterial mud is salvaged using a fishing net with a pore diameter of 0.149 mm;

In step 3, the salvaged cyanobacterial mud, activated sludge, and water are placed in an anaerobic fermentation device at a volume ratio of 1:1:1, and fermented in an environment of 20.2° C. and a pH value of 8.3 for 90 days for recycling.

Further, the volume ratio of the mixed flocculant to the water body to be flocculated during the flocculation in step 2 is 1:10, and the temperature of the water body to be flocculated is 5°C to 30°C.

Further, the anaerobic fermentation device includes a large-diameter drum, and a vent hole is drilled on the top cover of the barrel. The other end is placed under the water surface to seal.

The beneficial effects of the present invention are as follows: the present invention uses clay flocculants in combination, improves the flocculation effect of the flocculants, and makes the treatment of cyanobacterial blooms in the water body more thorough; the mixing process of various flocculants is simple, the mixing cost is low, and the prepared mixed The flocculant is economical, feasible and non-toxic, and will not cause secondary pollution to the water body after application; the mixed flocculant is used to treat cyanobacterial blooms in the water body. The treatment process is simple and thorough, which can effectively curb the eutrophication of the water body and restore the ecosystem balance.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to these drawings without creative efforts.

Figure 1 is a flow chart for the management of cyanobacterial blooms.

Figure 2 is a graph showing the effect of cyanobacterial fermentation biogas slurry on the plant height of lettuce.

Figure 3 is a graph showing the effect of cyanobacterial fermentation biogas slurry on the fresh weight of lettuce.

Figure 4 is a graph showing the effect of cyanobacterial fermentation biogas slurry on the chlorophyll content of lettuce.

Figure 5 is a graph showing the effect of cyanobacterial fermentation biogas slurry on the nitrate content of lettuce.

Figure 6 is a graph showing the effect of cyanobacterial fermentation biogas slurry on lettuce soluble sugar.

Fig. 7 is a graph showing changes in the content of available N in potted soil.

Figure 8 is a graph showing changes in the content of available P in potted soil.

Fig. 9 is a graph showing changes in the content of organic matter in potted soil.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

The mixed flocculant is composed of three-grade sepiolite wool, talc and diatomite with a mass ratio of (1-4): (3-12): (2-8). When the mass ratio to diatomite is 1:12:8, the prepared mixed flocculant has better effect.

As shown in Figure 1, the method of using mixed flocculants to control cyanobacterial blooms includes the following steps:

Step 1, prepare a mixed flocculant, weigh three grades of sepiolite wool, talc and diatomite according to the mass ratio, mix the raw materials and place them in an electronic stirrer for 5 minutes at room temperature, stir for 1 hour, and repeat the above The mixed flocculant is obtained three times in the process, stirring and standing to make the talc and diatomite fully fill in the gaps of the third-grade sepiolite wool, so that the flocculated particles in the mixed flocculant are evenly dispersed, and the structure of the flocculation particles will not be damaged;

Step 2, place a fishing net with a pore size of 0.149mm at the bottom of the water body, put the mixed flocculant into the water body and stir, and perform flocculation and sedimentation. The volume ratio of the mixed flocculant to the water body is 1:10, and the temperature of the water body to be flocculated is 1:10. Keep at 5℃～30℃, after flocculation for 6 hours, take back the scooping net filled with the mixed flocculant and flocculation group; first put it into the scooping net to form the intercepting body, and the flocs accumulate and coagulate on the intercepting body to form a large number of flocs. The agglomeration plays a role in shortening the gravity sedimentation distance of the floc particles. On the other hand, the interception, adsorption and contact cohesion of the flocs are used to effectively improve the removal efficiency of the floc particles and the organic matter in the water;

The mixed flocculant has good thermal stability and has a wide range of temperature adaptation to the reaction system. When the volume ratio of flocculant to water is 1:10 and the flocculation time is 6h, the mixed flocculant can flocculate most of the cyanobacteria into clusters, and the flocculation The structure of the flocculation is relatively stable. At this time, salvaging the flocculation can completely remove the cyanobacteria in the water body and restore the balance of the water body ecosystem;

Step 3, prepare an anaerobic fermentation device, put the salvaged cyanobacterial mud, activated sludge and water in the anaerobic fermentation device according to a volume ratio of 1:1:1, and ferment for 90 days at 20.2 ° C and a pH value of 8.3 , the upper biogas slurry obtained; the anaerobic fermentation device includes a large-diameter drum, the top cover of the drum is punched as an exhaust hole, one end of the gas pipeline is inserted into the exhaust hole, and the outside of the gas pipeline and the exhaust hole are blocked The other end of the gas pipe is inserted into the water to prevent air from entering the fermenter.

Activated sludge has a large surface area, many internal pores, strong adsorption capacity, and the ability to degrade organic matter. The activated sludge enters the fermentation system for enhanced coagulation, which can improve the removal rate of colloids, suspended solids, algae and other impurities in the water body; fermentation broth The pH of the water is positively correlated with the growth of algae. With the increase of pH, the number of algae gradually increases, but the increase of pH will affect the flocculation effect, which is not conducive to the removal of water turbidity. Therefore, at 20.2 °C, when the pH is maintained at 8.3 Fermentation works best.

The secondary utilization of salvaged materials reduces the pollution of salvaged materials to the environment and solves the storage problem of salvaged materials; fermentation biogas slurry mainly contains nitrogen and phosphorus elements, which can increase plant chlorophyll, soluble sugar and starch content after watering plants. Toxic side effects on plants.

Due to the influence of many factors such as fermentation process and fermentation output results, biogas production is not economical. It is of realistic and far-reaching significance to select the clay flocculant with the best flocculation effect to control cyanobacterial bloom pollution. Comprehensive treatment of cyanobacteria-contaminated water bodies, analysis and comparison of related indicators, to find the optimal mixing ratio of mixed flocculants and verify through experiments, the application of mixed flocculants can make the separation of algae water completely and the cyanobacteria treatment cycle shortened.

According to the dosage of mixed flocculants and the mass ratio of raw materials, it is known that 200g-800g of tertiary sepiolite wool, 600g-2400g of talc and 400g-1600g of diatomaceous earth need to be put into the water body of ^1m3 . The market prices of talc and diatomite are: 1600 yuan/t, 1500 yuan/t, 2000 yuan/t respectively. It can be seen that the cost of mixed flocculants is low and economical.

The amount of biogas produced by the salvaged cyanobacteria fermented at 20.2 °C was 487.3 mL/g, and the volume content of methane in the biogas was 64.91%. Now that the eutrophication of water is becoming more and more serious, the use of eutrophic water flocculation for biogas fermentation can provide a large amount of water. resources; anaerobic fermentation of cyanobacteria as biomass raw materials can be industrialized on a large scale without dehydration, and a large number of intermediate products that can be used as nutrients are produced during the fermentation process, and algal toxins are also degraded to a certain extent. Therefore, the reduction, harmlessness and resource utilization of cyanobacteria can be realized, which can be safely used for plant irrigation, and the application amount of compound fertilizers is reduced, thereby reducing the accumulation of compound fertilizers in plants and the pollution of compound fertilizers to the environment.

Example 1

Taking the three-level sepiolite wool, talc and diatomaceous earth as factors, each factor is set to three levels, and the L ₉ (3 ⁴ ) table is used for orthogonal design, and the optimal formula of the mixed flocculant is selected. The orthogonal factor The table is shown in Table 1, the three-factor and three-level orthogonal table is shown in Table 2, and the analysis of the orthogonal experiment results is shown in Table 3; The volume ratio of the flocculant is 1:10, add each mixed flocculant in Table 3 in each beaker, and set 1000 mL of algae liquid as a control group. Stir for 1 min, and then take the liquid 3 cm below the liquid surface to measure the turbidity and absorbance after 0 min, 15 min, 30 min, 60 min, 120 min, and 180 min respectively.

Prepare turbidity standard solution according to ISO7027-1984, read the standard turbidity of each sample on the standard curve, then

Table 1 Flocculant Orthogonal Test Factor Level Table

Table 2 Three-factor and three-level orthogonal table

Table 3 Orthogonal test range analysis table

It can be seen from Table 2 that the removal rate of the orthogonal experimental group ranges from 72% to 83%, the removal rate of experimental group 8 is the lowest, the removal rate of NTU and cyanobacteria are 72.9% and 72.66%, respectively, and the removal rate of experimental group 3 is the highest. , NTU removal rate and cyanobacterial removal rate were 83.48% and 83.26%, respectively; the lowest cost of experimental group 1 was 1.01 yuan, the highest cost of experimental group 3 was 3.56 yuan, and the costs of other experimental groups ranged from 1 to 3 yuan , the cost is lower.

In Table 3, K ₁ , K ₂ , and K ₃ are the sum of the corresponding removal rate values in the experiments of the first level, the second level, and the third level, respectively, and k ₁ , k ₂ , and k ₃ represent the average value of the removal rate, respectively. , it can be seen from the range analysis that the primary and secondary order of the influence of factors A, B and C on the flocculation effect is C>B>A, measured by the NTU removal rate and the cyanobacteria removal rate, the best formula for the orthogonal test is C ₃ B ₃ A ₁ , that is, when the input amount of diatomite in the mixed flocculant is 0.8g, the input amount of talc is 1.2g, and the input amount of third-grade sepiolite wool is 0.1g, the flocculation effect on cyanobacteria water is the best.

Example 2

The flocculated cyanobacteria in the 3 beakers of the experimental group of Example 1 were taken out, put into a fermenter in a volume ratio of 1:1:1 with activated sludge and water and sealed, and fermented at 20.2 ° C for three months to obtain an upper-layer fermentation biogas slurry, The degradation characteristics of the fermented biogas slurry are shown in Table 4. It can be seen from Table 4 that it takes a long time for the salvaged cyanobacteria to degrade under natural conditions. The content of algal toxins MC-RR and MC-LR can be reduced to below the drinking water standard on the 8th day of fermentation, which greatly reduces the degradation process of the cyanobacterial salvage. Improved degradation efficiency.

Table 4 Degradation characteristics of algal toxins

Dilute the biogas slurry with clean water to the volume ratio of 100%, 75%, 50% and 25%; select lettuce seeds with normal and uniform shape and scatter them into the flowerpot. Consistently left in the pots, each pot was planted with 3 lettuces. After 20 days, each treatment group was irrigated with different volume concentrations of fermented biogas slurry. The control group was irrigated with the same amount of clear water. Weight, chlorophyll content, nitrate content, soluble sugar, to determine the impact of cyanobacterial fermentation biogas slurry on the quality of lettuce, the test results are shown in Figures 2-6, it can be seen from Figures 2-6 that the biogas slurry produced by the fermentation of the present invention has an impact on lettuce strains Height, weight, chlorophyll content, nitrate content, and soluble sugar content all have a promoting effect, and with the increase of the biogas slurry volume concentration, the promoting effect is more significant, and although the present invention increases the nitrate content in the lettuce, but The nitrate content in lettuce is still lower than the limit standard in GB19338-2003 "Limited Nitrate in Vegetables", and far below the overall level of nitrate content in leafy vegetables in China, which is 2000-3000 mg/kg. The quality of cyanobacteria has been significantly improved, and the use of cyanobacteria to prepare biogas slurry has good application prospects, which can be used as post-treatment for salvage cyanobacteria, and solve the problems of cyanobacteria accumulation and secondary infiltration pollution.

The available N content, available P content and organic matter content of potted soil before and after irrigating biogas slurry were detected. The test results are shown in Figures 7 to 9. It can be seen from Figure 7 that fermented biogas slurry can increase the available N content in the soil, and Figure 8 shows that Fermented biogas slurry can increase the content of available P in the soil. It can be seen from Figure 9 that the fermented biogas slurry can also increase the content of organic matter in the soil, and the increase of available N, the increase of available P, and the increase of organic matter are all the same as those of fermented biogas. The volume concentration of the liquid is directly proportional, that is, the fermented biogas slurry can increase the nutrients in the soil, promote the growth and development of plants, reduce the use of chemical fertilizers and the accumulation of chemical reagents in plants, and improve the safety of plants.

Each embodiment in this specification is described in a related manner, and the same and similar parts between the various embodiments may be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, as for the system embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and for related parts, please refer to the partial descriptions of the method embodiments.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims (5)

1. The mixed flocculant is characterized in that, the mixed flocculant is formed by mixing the three-stage sepiolite wool, talc and diatomite whose mass ratio is (1～4): (3～12): (2～8). . 2 . The mixed flocculant according to claim 1 , wherein the mass ratio of tertiary sepiolite wool, talc and diatomite is 1:12:8. 3 . 3. the method for using the mixed flocculant described in any one of claims 1 to 2 to control cyanobacteria blooms, is characterized in that, specifically comprises the following steps: Step 1: Weigh the third-grade sepiolite wool, talc and diatomite according to the mass ratio, mix the raw materials, place them in an electronic stirrer, stir for 5 min, let stand for 1 h, repeat stirring and let stand three times to obtain a mixed flocculant; In step 2, the mixed flocculant is evenly put into the water body, stirred and dispersed, and after flocculation for 6 hours, the cyanobacterial mud is salvaged using a fishing net with a pore diameter of 0.149 mm; In step 3, the salvaged cyanobacterial mud, activated sludge, and water are placed in an anaerobic fermentation device at a volume ratio of 1:1:1, and fermented in an environment of 20.2° C. and a pH value of 8.3 for 90 days for recycling. 4. the method for controlling cyanobacterial blooms with mixed flocculant according to claim 3, it is characterized in that, the volume ratio of mixed flocculant and water body to be flocculated is 1:10 during flocculation in described step 2, and the temperature of water body to be flocculated is 1:10. 5℃～30℃. 5. the method for controlling cyanobacterial blooms with mixed flocculant according to claim 3, is characterized in that, described anaerobic fermentation device comprises large-diameter drum, and is drilled with vent hole on the top cover of barrel, vent hole Connect one end of the gas delivery pipe, seal the gap between the exhaust hole and the gas delivery pipe, and place the other end of the gas delivery pipe under the water surface for sealing.

Images