Denitrification and defluorination filler, preparation method thereof and photovoltaic wastewater denitrification and defluorination method

Abstract

The invention provides a denitrification and defluorination filler, a preparation method thereof and a photovoltaic wastewater denitrification and defluorination method, the denitrification and defluorination filler has a porous structure, and the defluorination filler comprises activated carbon, a reduced sulfur source, sodium bicarbonate, calcium carbonate and trace elements; the density rho of the nitrogen and fluorine removal filler is more than 0g / m < 3 > and less than 1g / m < 3 >. The filler performs nitrogen and fluorine removal based on a sulfur autotrophic denitrification technology, the activated carbon and the porous structure provide more attachment space for sulfur autotrophic bacteria, the reduced sulfur source provides an electron donor for sulfur autotrophic denitrification, and the sodium bicarbonate provides a carbon source for sulfur autotrophic denitrification and keeps acid-base balance. Therefore, the nitrogen and fluorine removal filler provided by the invention enables sulfur autotrophic bacteria to continuously perform denitrification reaction so as to remove nitrate ions in the water body, and calcium carbonate and activated carbon can remove fluorine ions in the water body. Therefore, the denitrification and defluorination filler can simultaneously perform denitrification and defluorination on a water body, and is suitable for purification treatment of high-concentration nitrate wastewater in the photovoltaic industry.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and in particular to a denitrification and defluorination filler and a preparation method thereof, as well as a photovoltaic wastewater denitrification and defluorination method. Technical Background

[0002] As a new energy industry, the photovoltaic industry aims to reduce environmental pollution and achieve efficient energy supply. However, the actual production process of photovoltaic solar panels not only involves the use of various toxic and hazardous substances, but also releases large amounts of pollutants into water and air, which conflicts with the original goal.

[0003] The texturing, phosphorus diffusion, etching, and pickling processes in the production of monocrystalline and multicrystalline silicon wafers utilize large quantities of chemicals such as hydrofluoric acid, nitric acid, phosphorus oxychloride, and isopropyl alcohol. Consequently, wastewater produced in this process exhibits the following characteristics: large volumes of wastewater and a complex pollutant composition. Specifically, this wastewater contains a variety of pollutants, including polyethylene glycol, nitrate ions, surfactants, and fluoride ions. These pollutants are characterized by high concentrations of these substances, as well as significant pH fluctuations. These wastewater characteristics pose significant challenges to wastewater treatment in the photovoltaic industry.

[0004] The "Battery Industry Pollutant Emission Standard" (GB30484-2013) sets limits on total nitrogen and fluoride ion emissions, stipulating that starting in 2016, total nitrogen emissions from the battery industry's wastewater must be below 15mg / L, and fluoride concentrations must be below 8mg / L. For fluoride removal, traditional primary coagulation and sedimentation tanks can only reduce fluoride ions to 15mg / L-20mg / L, which falls short of the required emission standards. To meet these standards, deep fluoride removal is still required. Summary of the Invention

[0005] One of the purposes of the present application is to provide a denitrification and defluorination filler and a preparation method thereof, as well as a photovoltaic wastewater denitrification and defluorination method.

[0006] The first aspect of the present application provides a denitrification and defluorination filler, wherein the denitrification is based on sulfur autotrophic denitrification technology, the denitrification and defluorination filler has a porous structure, and the denitrification and defluorination filler includes the following components: activated carbon, a reduced sulfur source, sodium bicarbonate, calcium carbonate and trace elements; the density ρ of the denitrification and defluorination filler is: 0g / m 3 <ρ<1g / m 3 .

[0007] The denitrification and defluorination filler is based on the sulfur autotrophic denitrification technology for denitrification and fluoridation. The activated carbon and porous structure provide a larger attachment space for sulfur autotrophic bacteria. The reduced sulfur source provides an electron donor and energy for sulfur autotrophic denitrification. Specifically, the reduced sulfur source releases electrons through an oxidation reaction, driving nitrate to be reduced to nitrogen gas, while meeting the energy requirements for microbial growth; sodium bicarbonate provides a carbon source for sulfur autotrophic bacteria and maintains the acid-base balance of the denitrification reaction in the pores. Therefore, the denitrification and defluoridation filler of the present application enables sulfur autotrophic bacteria to continuously and efficiently carry out denitrification reactions, thereby removing nitrate ions in the water body, the calcium ions in calcium carbonate can remove fluoride ions in the water body, and the carbonate ions in calcium carbonate can serve as a carbon source for sulfur autotrophic bacteria. On the other hand, the activated carbon that provides attachment space for sulfur autotrophic bacteria can also adsorb fluoride ions in the water body, and the low density of activated carbon makes the density of the denitrification and defluoridation filler lower than that of the water body. Therefore, the various components in the denitrification and defluorination filler of the present application can cooperate with each other to achieve simultaneous denitrification and defluorination of water bodies, and are suitable for the purification treatment of high-concentration nitrate wastewater in the photovoltaic industry.

[0008] Therefore, the denitrification and defluorination filler in this application integrates multiple multifunctional materials, and the effects of each material synergize with each other. This synergy enables the denitrification and defluorination filler in this application to achieve continuous denitrification by sulfur autotrophic bacteria using only a small amount of material, thereby reducing the nitrate and fluoride ion content in wastewater. Furthermore, the denitrification and defluorination filler in this application does not contain other toxic and harmful substances and will not affect the environment or organisms.

[0009] As for the precipitation generated by the removal of fluoride ions, since the density of the denitrification and defluorination filler is relatively low and is affected by greater fluctuations in the water body, the low-density denitrification and defluorination filler can quickly and efficiently separate the generated precipitation from the outside of the denitrification and defluorination filler through the developed pore structure when it is suspended and shaken, making it difficult for the material to be clogged by the precipitation, allowing the sewage to continuously enter the pores of the denitrification and defluorination filler, and the water body can continuously contact the sulfur autotrophic bacteria in the denitrification and defluorination filler, so that the nitrogen-containing water body is continuously denitrified. Therefore, in this application, the sulfur autotrophic bacteria can continuously and efficiently contact the sewage over a large area, and the sewage treatment is more efficient.

[0010] The denitrification and defluorination filler of the present application will not sink to the bottom of the reactor like traditional fillers due to its composition and manufacturing process. It can slowly release the effective ingredients in the denitrification and defluorination filler in the water body as the denitrification and defluorination reaction process progresses. The denitrification and defluorination filler can maintain its shape and performance unchanged during long-term operation, has stability and durability, and reduces replacement costs.

[0011] The denitrification and defluorination filler can be suspended on the surface of the water body because the denitrification and defluorination filler of this application has a density of less than 1g / m 3 Low density material, in some embodiments of the present invention, the density value of the denitrification and defluorination filler includes 0.99g / m3 , 0.95g / m 3 , 0.9g / m 3 , 0.85g / m 3 , 0.8g / m 3 , 0.75g / m 3 , 0.7g / m 3 , 0.65g / m 3 , 0.5g / m 3 , 0.45g / m 3 , 0.4g / m 3 , 0.35g / m 3 , 0.3g / m 3 , 0.25g / m 3 , 0.2g / m 3 , 0.15g / m 3 , 0.1g / m 3 , 0.5g / m 3 , 0.1g / m 3 , and values ​​between any two of the above values. The denitrification and defluorination filler of the present application uses low-density materials, which will not hinder the flow of water, can reduce the operating burden of the system, and help improve hydraulic flow and reaction efficiency.

[0012] In the present application, the reduced sulfur source includes a composite sulfur source formed by combining at least one or more of elemental sulfur, pyrite, sodium thiosulfate, and sodium sulfide.

[0013] Sulfur autotrophic denitrification is different from traditional heterotrophic biochemical processes. The denitrification process uses sulfur-containing compounds or elemental sulfur as electron donors and can complete denitrification without adding a carbon source. Therefore, sulfur autotrophic denitrification can effectively reduce carbon emissions and lower carbon source consumption.

[0014] In the denitrification and defluorination filler provided in this application, sulfur autotrophic denitrification uses inorganic carbon sources (such as CO2, HCO3 - ) as the sole carbon source, eliminating the need for additional organic carbon sources and thus reducing operating costs. Sulfur autotrophic denitrification produces primarily water and a small amount of sulfate as byproducts, avoiding the greenhouse gas emissions that can occur with traditional heterotrophic denitrification. Nitrogen removal using sulfur autotrophic bacteria is suitable for treating high-concentration nitrate wastewater in the photovoltaic industry. Furthermore, the autotrophic bacteria in water purification systems using sulfur autotrophic denitrification have a long lifespan and produce little sludge, resulting in lower disposal costs for excess sludge than traditional biochemical processes.

[0015] In some embodiments of the present application, the density ρ of the denitrification and defluorination filler is: 0.7 g / m 3 ≤ρ≤0.8g / m 3 In some embodiments of the present invention, the density of the denitrification and defluorination filler is 0.71 g / m 3, 0.72g / m 3 , 0.73g / m 3 , 0.74g / m 3 , 0.75g / m 3 , 0.76g / m 3 , 0.77g / m 3 , 0.78g / m 3 , 0.79g / m 3 , 0.8g / m 3 And the value between any two of the above values; when the density of the denitrification and defluorination filler is 0.7g / m 3 -0.8g / m 3 When the temperature is within the specified range, the denitrification and defluorination filler has a large specific surface area, which is conducive to the attachment of microorganisms, can provide abundant attachment sites, is conducive to the growth of sulfur autotrophic bacteria, and improves the ability to degrade pollutants.

[0016] In some embodiments of the present application, the porosity of the denitrification and defluorination filler is 40% to 55%, for example, it may be 40%, 45%, 50% or 55%.

[0017] In some embodiments of the present application, the pore size of the denitrification and defluorination filler is 50 μm to 400 μm, for example, 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, or 400 μm, etc. Such a configuration is conducive to the attachment of microorganisms and other components, and is more conducive to the growth of sulfur autotrophic bacteria.

[0018] In some embodiments of the present application, the mass ratio of the activated carbon, reduced sulfur source, sodium bicarbonate, calcium carbonate and trace elements is: (15-25): (35-55): (5-15): (18-29): (1-2).

[0019] In some embodiments of the present invention, based on the total mass of the denitrification and defluorination filler, the mass proportion of the reduced sulfur source is 35%-55%; the mass proportion of the sodium bicarbonate is 5%-15%, the mass proportion of the calcium carbonate is 18%-29%; the mass proportion of the trace elements is 1%-2%; and the mass proportion of the activated carbon is 15%-25%.

[0020] In some embodiments of the present invention, the reduced sulfur source includes elemental sulfur, and the activated carbon includes aluminum-loaded activated carbon.

[0021] In some embodiments of the present invention, based on the total mass of the denitrification and defluorination filler, the mass proportion of elemental sulfur is 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 55% and values ​​between any two of the foregoing values.

[0022] In some embodiments of the present invention, based on the total mass of the denitrification and defluorination filler, the mass of the sodium bicarbonate accounts for 5%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15% and values ​​between any two of the foregoing values.

[0023] In some embodiments of the present invention, based on the total mass of the denitrification and defluorination filler, the mass of the calcium carbonate accounts for 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29% and values ​​between any two of the foregoing values.

[0024] In some embodiments of the present invention, based on the total mass of the denitrification and defluorination filler, the mass of the trace elements accounts for 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2% and values ​​between any two of the foregoing values.

[0025] In some embodiments of the present invention, based on the total mass of the denitrification and defluorination filler, the mass of the aluminum-loaded bioactivated carbon accounts for 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25% and values ​​between any two of the foregoing values.

[0026] The reduced sulfur source includes at least one of elemental sulfur, pyrite, sodium thiosulfate, and sodium sulfide; and the activated carbon includes at least one of biological activated carbon and aluminum-loaded activated carbon.

[0027] In some embodiments of the present invention, the reduced sulfur source includes elemental sulfur, which is not easily oxidized and dissolved, releases sulfur relatively slowly, and can stably provide an electron donor in the water treatment system, avoiding fluctuations in treatment efficiency caused by rapid consumption. It can also avoid the inhibition of microorganisms caused by excessive instantaneous concentration due to rapid dissolution, or secondary pollution problems such as hydrogen sulfide escape and heavy metal precipitation and re-dissolution caused by rapid dissolution. Therefore, the denitrification and defluorination filler of the present application has the effect of long service life and avoidance of secondary pollution.

[0028] In some embodiments of the present invention, elemental sulfur includes various elemental sulfur-containing raw materials mainly containing elemental sulfur, such as at least one of sulfur granules, industrial-grade sulfur blocks, or stone sulfur.

[0029] In some embodiments of the present invention, the activated carbon is aluminum-loaded activated carbon. The aluminum-loaded activated carbon has aluminum hydroxyl (Al-OH) functional groups on its surface that can undergo coordination exchange reactions with fluoride ions (F-) in water to form stable Al-F complexes. Moreover, since the activated carbon has a high specific surface area, the aluminum-loaded activated carbon exhibits better fluorine adsorption capacity. The aluminum ions (Al3+) in the water can form insoluble precipitates with fluoride ions (F-), such as aluminum fluoride (AlF3), to further reduce the fluoride concentration in the water. Therefore, the denitrification and defluorination filler of the present application can also achieve the removal of fluoride in wastewater.

[0030] In some embodiments of the present invention, the activated carbon includes at least one of biological activated carbon and aluminum-loaded activated carbon.

[0031] In some embodiments of the present invention, the activated carbon is biological activated carbon.

[0032] In some embodiments of the present invention, the activated carbon is aluminum-loaded biological activated carbon.

[0033] In some embodiments of the present invention, the trace elements include at least one of aluminum, magnesium, molybdenum, copper, cobalt, zinc, and iron.

[0034] In some embodiments of the present invention, the trace elements include aluminum, magnesium, molybdenum, copper, cobalt, zinc, and iron.

[0035] In some embodiments of the present invention, the trace elements include at least one of aluminum sulfate, magnesium chloride, sodium molybdate, copper sulfate, cobalt chloride, zinc sulfate, and ferric chloride.

[0036] In some embodiments of the present invention, the trace elements include aluminum sulfate, magnesium chloride, sodium molybdate, copper sulfate, cobalt chloride, zinc sulfate, and ferric chloride.

[0037] In some embodiments of the present invention, the mass ratio of aluminum sulfate, polyaluminum chloride, magnesium chloride, sodium molybdate, copper sulfate, cobalt chloride, zinc sulfate, and ferric chloride in the trace elements is (350-400):(200-300):(150-250):(4-8):(1-3):1:(8-12):(50-70). This configuration provides the sulfur autotrophic bacteria with various trace element nutrients required for their reproduction, thereby facilitating the reproduction of the sulfur autotrophic bacteria.

[0038] In some embodiments of the present invention, the mass ratio of aluminum sulfate, polyaluminum chloride, magnesium chloride, sodium molybdate, copper sulfate, cobalt chloride, zinc sulfate, and ferric chloride in the trace elements is 372:248:208:6:2:1:10:60. This saves costs while ensuring that the sulfur autotrophic bacteria are not lacking in various nutrients.

[0039] The second aspect of the present application provides a method for preparing the denitrification and defluorination filler according to the first aspect, the preparation method comprising the following steps:

[0040] 1. Mixing sodium bicarbonate, activated carbon and calcium carbonate to obtain a first mixture;

[0041] 2. heating the reduced sulfur source to a molten state and then mixing it with the trace elements to obtain a second mixture;

[0042] 3. Evenly mix the first mixture and the second mixture, cool and shape them to obtain the denitrification and defluorination filler.

[0043] In the above preparation method, the molten reduced sulfur source carbon energy can be fully mixed with the trace elements, and the heat of the molten reduced sulfur source causes part of the sodium bicarbonate to decompose to produce CO2 and Na2CO3, and part of the calcium carbonate to decompose to produce CaO and CO2; the gas produced by the decomposition will form pores inside the material, and after cooling, a denitrification and defluorination filler in which sodium bicarbonate, activated carbon, calcium carbonate, and reduced sulfur source are evenly dispersed and tightly combined is obtained. The obtained denitrification and defluorination filler has a continuous and through cave structure like an ant nest, and the uneven inner surface increases the specific surface area, provides good growth conditions for sulfur autotrophic bacteria, and the attached microorganisms are not easy to fall off.

[0044] Based on the second aspect, in some embodiments of the present invention, the particle size of the reduced sulfur source is 20 mesh to 100 mesh;

[0045] Based on the second aspect, in some embodiments of the present invention, the particle size of the sodium bicarbonate is 20 mesh to 200 mesh;

[0046] Based on the second aspect, in some embodiments of the present invention, the particle size of the activated carbon is 100 mesh to 400 mesh;

[0047] Based on the second aspect, in some embodiments of the present invention, the particle size of the calcium carbonate is 200 mesh to 500 mesh.

[0048] Based on the second aspect, in some embodiments of the present invention, the calcium carbonate can be obtained by grinding calcium carbonate-containing materials such as limestone and shells. In this application, when the mesh sizes of sodium bicarbonate and calcium carbonate required for the filler are within the aforementioned ranges, the raw materials in the denitrification and defluorination filler can be evenly distributed within the filler and have a large contact area with the sewage, thereby increasing the rate of sulfur autotrophic denitrification.

[0049] Based on the second aspect of the present application, in some embodiments of the present invention, in step 1, sodium bicarbonate, aluminum-loaded biological activated carbon, and calcium carbonate powder are mixed in a mass ratio of 1: (1.5-2): (1.8-2) to obtain a first mixture;

[0050] Based on the second aspect of the present application, in some embodiments of the present invention, in step 2, the mass of the reduced sulfur source accounts for 45%-50% of the total mass of the denitrification and defluorination filler.

[0051] Based on the second aspect of the present application, in some embodiments of the present invention, in step 2, the mass of the trace elements accounts for 1%-2% of the total mass of the denitrification and defluorination filler;

[0052] Based on the second aspect of the present application, in some embodiments of the present invention, the following steps are included: in step 1, the mass ratio of sodium bicarbonate: activated carbon: calcium carbonate is 1:2:2.

[0053] Based on the second aspect of the present application, in some embodiments of the present invention, the following steps are included: in step 1, the mass ratio of sodium bicarbonate: activated carbon: calcium carbonate is 1:1.5:1.5.

[0054] Based on the second aspect of the present application, in some embodiments of the present invention, step 2 of the aforementioned method for preparing the denitrification and defluorination filler includes: the reduced sulfur source is elemental sulfur.

[0055] Based on the second aspect of the present application, in some embodiments of the present invention, the reduced sulfur source is sulfur, the activated carbon is aluminum-loaded biological activated carbon, and in steps one and two, the mesh size of sodium bicarbonate is in the range of 30-50, the mesh size of aluminum-loaded biological activated carbon is in the range of 120-150, the mesh size of calcium carbonate is in the range of 250-300, and the mesh size of sulfur is in the range of 30-50.

[0056] Based on the second aspect of the present application, in some embodiments of the present invention, in step 2, the reduced sulfur source includes elemental sulfur, and heating the reduced sulfur source to a molten state includes: adding the elemental sulfur into a container, controlling the heating temperature within the range of 120° C. to 140° C. until the elemental sulfur melts, maintaining the heating temperature within the range of 100° C. to 110° C. after the elemental sulfur melts, and maintaining stirring during the heating process;

[0057] Based on the second aspect of the present application, in some embodiments of the present invention, in step 2, heating the reduced sulfur source to a molten state and then mixing it with the trace elements to obtain the second mixture includes: adding the trace elements to the melted elemental sulfur and continuously stirring for 5 minutes to obtain the second mixture;

[0058] Based on the second aspect of the present application, in some embodiments of the present invention, in step three, mixing the first mixture with the second mixture includes: stirring the first mixture of step one and the second mixture of step two together for 5 minutes to mix them.

[0059] In a third aspect, the present application provides an application of the denitrification and defluorination filler as described in the first aspect in the field of denitrification and defluorination of photovoltaic wastewater.

[0060] In a fourth aspect, the present application provides a method for denitrification and defluorination of photovoltaic wastewater, comprising: attaching sulfur autotrophic bacteria to the denitrification and defluorination filler as described in the first aspect and curing it, and then putting it into the photovoltaic wastewater to be treated for denitrification and defluorination.

[0061] Based on the fourth aspect of the present application, in some embodiments of the present invention, attaching sulfur autotrophic bacteria to the denitrification and defluorination filler includes: culturing the denitrification and defluorination filler with sulfur autotrophic bacteria liquid for one week.

[0062] Based on the fourth aspect of this application, in some embodiments of the present invention,

[0063] The curing step includes culturing the denitrification and defluorination filler with a sulfur autotrophic bacteria solution for one week, wherein the culturing conditions include: 34.5°C to 35.5°C, a pH of 6.5 to 7.5, and an inoculum of 800 mg / L, so that the sulfur autotrophic bacteria can better grow in the pores of the filler.

[0064] Hydraulic retention time refers to the average time that the wastewater to be treated stays in the reactor, which reflects the length of time the wastewater is in contact with the treatment medium.

[0065] Based on the fourth aspect of the present application, in some embodiments of the present invention, the sewage to be treated has at least one of the following characteristics:

[0066] (1) The fluoride ion concentration in the sewage to be purified is 15 mg / L-30 mg / L;

[0067] (2) The total nitrogen concentration in the sewage to be purified is 300 mg / L-1000 mg / L;

[0068] (3) The hydraulic retention time of the sewage to be purified is 2h-14h.

[0069] For nitrate nitrogen-containing wastewater, the general treatment method is to use traditional biochemical treatment (such as A / O, that is, the "anoxic / aerobic" process, which connects the anoxic section and the aerobic section in series to achieve the degradation of organic matter in the sewage, the removal of ammonia nitrogen, and the removal of some phosphorus). This requires consideration of the C / N balance. The C / N balance in A / O refers to the ratio of carbon (C) to nitrogen (N). This ratio directly affects the efficiency and cost of the denitrification process. On the one hand, the C / N balance requires the addition of sufficient external carbon sources to support denitrification. Otherwise, the denitrification reaction cannot be carried out effectively, resulting in a decrease in denitrification efficiency. However, excessive addition of carbon sources will also cause a sharp increase in treatment costs and may cause secondary pollution. Therefore, the problem of carbon-nitrogen balance needs to be considered in the traditional biochemical process, and it is relatively complex and difficult to control the biochemical process to achieve carbon-nitrogen balance.

[0070] The sodium bicarbonate in the denitrification and defluorination filler of the present application can provide a carbon source for sulfur autotrophic bacteria. Since the denitrification and defluorination process of the present application does not require the addition of a carbon source to the water body, the denitrification process of the present application does not need to consider the C / N balance, which simplifies the wastewater treatment process and reduces the wastewater treatment cost. Moreover, since acid is produced during the sulfur autotrophic denitrification reaction, the pH value decreases. When the pH value is too low, the activity of microorganisms will be inhibited, thereby reducing the denitrification efficiency. In addition, photovoltaic wastewater has the characteristic of large pH fluctuations. Therefore, maintaining an appropriate pH value is crucial for the smooth progress of the reaction. The sodium bicarbonate and calcium carbonate in the denitrification and defluorination filler of the present application can also maintain the pH in the reaction system for sulfur autotrophic bacteria, and can adapt to changes in water quality over a large range, and can handle the treatment needs of wastewater with different concentrations and complex components.

[0071] Hydraulic retention time has an important influence on the operation efficiency of sewage treatment, and a shorter hydraulic retention time can reduce the volume and construction cost of the container required for sewage treatment, but too short hydraulic retention time may cause the reaction efficiency in sewage treatment to decline. Therefore, selecting suitable hydraulic retention time is the key to optimizing reaction rate, and through the exploration of this application, when the hydraulic retention time is 2h-14h, the sewage treatment effect of this application is better, especially when the fluorine ion concentration in the sewage to be treated is 15mg / L-30mg / L and the total nitrogen concentration is 300mg / L-1000mg / L, the aforementioned hydraulic retention time can preferably remove the fluorine ion, the nitrate ion in the sewage. Under this hydraulic retention time, water inlet speed is less, reduces the dissolved oxygen entering the main denitrification zone, so as to facilitate sulfur autotrophic bacteria to carry out denitrification reaction, remove the nitrogen in the water body.

[0072] The denitrification and defluorination filler of the present application can achieve a denitrification load of 0.5 kg / (m 3 *d)-1.0kg / (m3*d), which is much better than the traditional water purification process and can effectively reduce the problems of large reactor footprint and high investment cost; the denitrification load here is calculated by the nitrogen concentration of inlet and outlet water and the amount of nitrogen removed. The specific calculation method is: denitrification load kg / (m 3 *d) = (influent nitrogen concentration - effluent nitrogen concentration) × daily treated water volume / packing volume.

[0073] Beneficial effects: The denitrification and defluorination filler provided by the present application can be used for photovoltaic wastewater treatment after being placed in a sulfur autotrophic bacteria liquid for one week, wherein the pore structure in the denitrification and defluorination filler provides a good attachment environment for sulfur autotrophic bacteria, and the reduced sulfur source in the denitrification and defluorination filler provides the sulfur autotrophic bacteria with the electron donor required for sulfur autotrophic denitrification; since the denitrification and defluorination filler of the present application has a low density and can be suspended on the surface of the water body, the surface of the water body is greatly affected by the water body fluctuation, and the low-density denitrification and defluorination filler can quickly and efficiently separate the generated precipitate from the outside of the denitrification and defluorination filler when it is suspended and shaken. Sodium bicarbonate regulates pH and provides a carbon source for sulfur autotrophic denitrification. Calcium carbonate provides a carbon source for sulfur autotrophic denitrification and can combine with fluoride ions in the water to achieve the effect of water defluoridation. Trace elements provide necessary trace element nutrients for sulfur autotrophic denitrification. The raw materials in the denitrification and defluoridation filler of this application are organically combined and cooperate with the porous holes of the raw materials to jointly achieve denitrification and defluoridation of the water body. The denitrification load in the traditional water purification process is 0.3kg / (m 3 *d)~0.5kg / (m 3 *d), the denitrification and defluorination filler of this application can achieve a denitrification load of 0.5kg / (m 3 *d)~1.0kg / (m 3 *d), which is an improvement over traditional water purification processes and can effectively reduce problems such as large reactor footprint and high investment costs; when the denitrification and defluorination filler of the present application is used to purify water bodies, it not only meets the actual needs of efficient denitrification and deep defluorination, but also does not need to consider problems such as C / N imbalance and excessive addition of carbon sources in traditional biochemical processes. Moreover, the denitrification and defluorination filler of the present application does not contain other toxic and harmful substances, produces less sludge, and will not affect the environment and organisms. The denitrification and defluorination filler of the present application has a low density, which is conducive to hydraulic flow, can reduce the operating burden of the water purification system, and improve the efficiency of sulfur autotrophic denitrification reaction. Through the denitrification and defluorination filler of the present application, the various materials in the present application are slowly released in the water body to avoid the water flow from washing away part of the materials. The denitrification and defluorination filler can maintain its shape and performance unchanged during long-term operation, reducing the cost of material replacement. DETAILED DESCRIPTION

[0074] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0075] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular also includes the plural. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0076] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0077] Example 1

[0078] A method for preparing a denitrification and defluorination filler comprises the following steps:

[0079] a) Sodium bicarbonate with a mesh size of 30-50 mesh, aluminum-loaded biological activated carbon with a mesh size of 120-150 mesh, and calcium carbonate powder with a mesh size of 250-300 mesh are fully stirred and mixed in a mass ratio of 1:2:2 to obtain a primary mixed material for later use;

[0080] b) Take 30-50 mesh sulfur particles accounting for 48% of the total mass of the denitrification and defluorination filler and put them into the reactor for heating. The heating temperature is set to 120°C-140°C. The reactor must be equipped with a stirring paddle for continuous stirring.

[0081] c) completely melting the sulfur in step b into liquid form, opening the reactor feed port and continuing stirring, while controlling the heating temperature to maintain at 100° C.-110° C.;

[0082] d) adding 2% by mass of trace elements into the reactor and continuing stirring for 5 minutes to obtain a secondary mixed material, specifically, the trace elements include aluminum sulfate (Al2(SO4)3), polyaluminum chloride (PAC), magnesium chloride (MgCl2), sodium molybdate (Na2MoO4), copper sulfate (CuSO4·5H2O), cobalt chloride (CoCl2·6H2O), zinc sulfate (ZnSO4·7H2O), and ferric chloride (FeCl3), and the mass ratio of aluminum sulfate, polyaluminum chloride, magnesium chloride, sodium molybdate, copper sulfate, cobalt chloride, zinc sulfate, and ferric chloride is 372:248:208:6:2:1:10:60;

[0083] e) adding the primary mixed material in step a into a reactor and stirring for 5 minutes to obtain a final mixed material;

[0084] f) After stirring, pour the final mixed filler from the reactor into a square mold (shape is not critical, as long as it is easy to disassemble) and cool to room temperature. After removing the mold, the denitrification and defluorination filler is obtained. The filler must be incubated with sulfur autotrophic bacteria for one week before being added to the reactor.

[0085] Due to its composition and manufacturing process, the filler will not sink to the bottom of the reactor like traditional fillers. Instead, it slowly releases its active ingredients in the water as the denitrification and defluorination reactions proceed. The sodium bicarbonate and calcium carbonate contained in the filler stabilize the pH in the reactor while sulfur autotrophic acid is produced, and also provide an inorganic carbon source for sulfur autotrophic bacteria. Simultaneously, the calcium ions released by the calcium carbonate couple with the aluminum-loaded biologically activated carbon, further enhancing the deep defluoridation effect. Fluoride ions in the wastewater are partially adsorbed by the biologically activated carbon, while others combine with calcium ions. The resulting precipitate, due to the filler's porous structure, settles quickly and does not accumulate within the filler, thus reducing any adverse effects on the filler during the defluoridation process.

[0086] Example 2

[0087] A solar photovoltaic plant in a certain city produces 10,000 m3 of fluorine-containing and nitrogen-containing wastewater per day. 3 / d, plus the daily domestic sewage treatment capacity reaches 20,000m 3 / d.

[0088] The factory's self-built wastewater treatment plant adopts a three-stage defluorination system + AO process. After the influent undergoes primary defluorination and precipitation, the average fluoride ion concentration in the effluent is 20 mg / L, the average TN (total nitrogen) concentration is 445 mg / L, and the average C / N (ratio of carbon (Carbon, C) to nitrogen (Nitrogen, N)) is 1.7. If deep defluorination with defluorination agents + traditional biochemical treatment is still used, a large amount of defluorination agents must be added in the deep defluorination and a large amount of carbon source must be added in the anoxic section to ensure that the total nitrogen and fluoride ion in the effluent meet the standards, which results in huge production costs.

[0089] In this embodiment, 55% sulfur powder is placed in a reactor and heated until liquid. Then, 1% of the total mass of trace elements is added and mixed evenly. Specifically, the trace elements include aluminum sulfate (Al2(SO4)3), polyaluminum chloride (PAC), magnesium chloride (MgCl2), sodium molybdate (Na2MoO4), copper sulfate (CuSO4·5H2O), cobalt chloride (CoCl2·6H2O), zinc sulfate (ZnSO4·7H2O), and ferric chloride (FeCl3). The mass ratio of aluminum sulfate, polyaluminum chloride, magnesium chloride, sodium molybdate, copper sulfate, cobalt chloride, zinc sulfate, and ferric chloride is 372:248:208:6:2:1:10:60. Then, 15% sodium bicarbonate and 29% calcium carbonate are added and mixed evenly. After cooling and forming, a porous denitrification and defluorination filler is obtained. The denitrification and defluorination filler prepared in this embodiment has a pore size distribution between 100 μm and 350 μm and a porosity between 42% and 53%.

[0090] The pilot project for the implementation of this embodiment replaced the original three-stage defluorination system + A / O denitrification process behind the original first-stage defluorination sedimentation tank of the sewage treatment plant. The above-mentioned filler was first cultured with sulfur autotrophic bacteria for one week and then put into the reactor. The reactor used a top-in and bottom-out method to treat wastewater. The total hydraulic retention time was 14 hours and the operating temperature was room temperature. After the system was running stably, the final effluent fluoride ion concentration and TN concentration reached the emission indicators of the "Battery Industry Pollutant Emission Standard" (GB30484-2013). The average effluent fluoride ion concentration was 5.8 mg / L, and the average effluent TN was 21 mg / L. The denitrification load of the special filler can reach 0.8 kg / (m 3 *d). The TN removal rate in the denitrification stage is over 95.3%, and the fluoride ion is removed simultaneously in the denitrification stage, with the filler fluoride removal rate reaching over 71%.

[0091] Example 3

[0092] The wastewater treatment station of a new energy technology company has a wastewater volume of 5000m 3 / d, the influent water quality has an average TN content of 698 mg / L and an average fluoride ion content of 23 mg / L. The filler used is prepared according to the preparation steps described in Example 1 using 35% by mass of sulfur powder, 1% of trace elements, 15% of sodium bicarbonate, 29% of calcium carbonate, and 20% of aluminum-loaded bioactivated carbon. The mass proportions of the denitrification and defluorination filler raw materials in the filler are shown in Table 1. The trace elements include aluminum sulfate (Al2(SO4)3), polyaluminum chloride (PAC), magnesium chloride (MgCl2), sodium molybdate (Na2MoO4), copper sulfate (CuSO4·5H2O), cobalt chloride (CoCl2·6H2O), zinc sulfate (ZnSO4·7H2O), and ferric chloride (FeCl3). The mass ratio of aluminum sulfate, polyaluminum chloride, magnesium chloride, sodium molybdate, copper sulfate, cobalt chloride, zinc sulfate, and ferric chloride is 372:248:208:6:2:1:10:60. The pore size distribution of the denitrification and defluorination filler prepared in this embodiment is between 80 μm and 400 μm, and the porosity is between 40% and 52%.

[0093] The filler was first cultured with sulfur autotrophic bacteria for one week before being put into the reactor. The pilot project after using the filler verified that the hydraulic retention time was 8 hours, the operating temperature was room temperature, the average fluoride ion concentration in the effluent was 3.5 mg / L, and the fluoride removal rate was stable at more than 85%; the average TN value in the effluent was 17.5 mg / L, the average TN removal rate was 97.5%, and the denitrification load of the special filler could reach 0.9 kg / (m 3 *d).

[0094] Example 4

[0095] The amount of wastewater discharged from a semiconductor factory in a certain city is 5000m3 per day. 3 / d, the average TN content of the wastewater is 779 mg / L, and the average fluoride ion content is 25 mg / L. The mass ratio of the filler used is 43% sulfur powder, 2% trace elements, 15% sodium bicarbonate, 20% aluminum-loaded biological activated carbon, and 20% calcium carbonate. The filler is prepared according to the preparation steps described in Example 1. Specifically, the trace elements include aluminum sulfate (Al2(SO4)3), polyaluminum chloride (PAC), magnesium chloride (MgCl2), sodium molybdate (Na2MoO4), copper sulfate (CuSO4·5H2O), cobalt chloride (CoCl2·6H2O), zinc sulfate (ZnSO4·7H2O), and ferric chloride (FeCl3). The mass ratio of aluminum sulfate, polyaluminum chloride, magnesium chloride, sodium molybdate, copper sulfate, cobalt chloride, zinc sulfate, and ferric chloride is 372:248:208:6:2:1:10:60. The pore size distribution of the denitrification and defluorination filler prepared in this embodiment is between 50 μm and 320 μm, and the porosity is between 48% and 55%.

[0096] The filler is first cultured with sulfur autotrophic bacteria for one week before being put into the reactor. The reactor uses a top-in and bottom-out method to treat wastewater, with a total hydraulic retention time of 10 hours and an operating temperature of room temperature. In a pilot project, it was verified that after using this filler, the average fluoride ion concentration in the effluent was below 3.2 mg / L, and the fluoride removal rate was stable at more than 87%; the average total nitrogen concentration in the effluent was 13 mg / L, and the average total nitrogen removal rate was more than 98.3%. The denitrification load of the special filler can reach 0.9 kg / (m 3 *d).

[0097] Example 5

[0098] The amount of wastewater discharged from a pharmaceutical workshop is 2000m3 per day. 3 / d, the wastewater quality has an average TN content of 899 mg / L and an average fluoride ion content of 24 mg / L. The filler used is made of 48% sulfur powder, 2% trace elements, 10% sodium bicarbonate, 20% aluminum-loaded biological activated carbon, and 20% calcium carbonate. The filler is made according to the production steps described in Example 1. Specifically, the trace elements include aluminum sulfate (Al2(SO4)3), polyaluminum chloride (PAC), magnesium chloride (MgCl2), sodium molybdate (Na2MoO4), copper sulfate (CuSO4·5H2O), cobalt chloride (CoCl2·6H2O), zinc sulfate (ZnSO4·7H2O), and ferric chloride (FeCl3). The mass ratio of aluminum sulfate, polyaluminum chloride, magnesium chloride, sodium molybdate, copper sulfate, cobalt chloride, zinc sulfate, and ferric chloride is 372:248:208:6:2:1:10:60. The pore size distribution of the denitrification and defluorination filler prepared in this embodiment is between 90 μm and 380 μm, and the porosity is between 45% and 54%.

[0099] The filler is first cultured with sulfur autotrophic bacteria for one week before being put into the reactor. The reactor uses a top-in and bottom-out method to treat wastewater, with a total hydraulic retention time of 2 hours and an operating temperature of room temperature. In a pilot project, it was verified that after using this filler, the average fluoride ion concentration in the effluent was below 2.5 mg / L, and the average fluoride removal rate was stable at more than 90%; the average effluent total nitrogen concentration was 8.9 mg / L, and the total nitrogen removal rate was more than 99.0%. The denitrification load of the special filler can reach 1.0 kg / (m 3 *d).

[0100] Table 1: Denitrification and defluorination filler parameters and water purification effects of Examples 2-5

[0101]

[0102]

[0103] Note: “-” in Table 1 means no aluminum-loaded bioactivated carbon was added.

[0104] The above four cases prove that when the use of aluminum-loaded biological activated carbon is added to the filler in Cases 3 and 4, the fluoride removal effect of the filler on wastewater is improved. When the mass ratio of sodium bicarbonate: sulfur powder is increased, the fluoride removal effect is improved. At the same time, the upper limit of the denitrification effect is also significantly improved.

[0105] It can be seen from Case 5 that when the mass ratio of elemental sulfur is 45%-50%, the mass ratio of sodium bicarbonate, aluminum-loaded biological activated carbon and calcium carbonate powder is 1:2:2, and the added mass ratio of trace elements is 2%, the prepared combined filler has a better effect on denitrification and defluorination of wastewater.

[0106] The present invention uses a denitrification and defluorination filler inoculated with sulfur autotrophic bacteria. The pores in the denitrification and defluorination filler provide a good attachment environment for the sulfur autotrophic bacteria, and the sulfur in the denitrification and defluorination filler provides the autotrophic bacteria with the electron donor required for sulfur autotrophic denitrification. Since the denitrification and defluorination filler of the present invention has a low density, it can be suspended on the surface of the water body. The surface of the water body is greatly affected by the water body fluctuation. When the low-density denitrification and defluorination filler is suspended and shaken, the generated precipitation can be quickly and efficiently separated from the outside of the denitrification and defluorination filler. The denitrification load of the denitrification and defluorination filler of the present invention can reach 0.5kg / (m 3 *d)-1.0kg / (m 3 *d), which is an improvement over traditional water purification processes and can effectively reduce problems such as large reactor footprint and high investment costs; when the denitrification and defluorination filler of the present application is used to purify water bodies, it not only meets the actual needs of efficient denitrification and deep defluorination, but also does not need to consider problems such as C / N imbalance and excessive addition of carbon sources in traditional biochemical processes. Moreover, the denitrification and defluorination filler of the present application does not contain other toxic and harmful substances, produces less sludge, and will not affect the environment and organisms. The denitrification and defluorination filler of the present application has a low density, which is conducive to hydraulic flow, can reduce the operating burden of the water purification system, and improve the efficiency of sulfur autotrophic denitrification reaction. Through the denitrification and defluorination filler of the present application, the various materials in the present application are slowly released in the water body to avoid the water flow from washing away part of the materials. The denitrification and defluorination filler can maintain its shape and performance unchanged during long-term operation, reducing the cost of material replacement.

[0107] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A denitrification and defluorination filler, characterized in that: The denitrification and defluorination filler has a porous structure and includes the following components: Activated carbon, reduced sulfur source, sodium bicarbonate, calcium carbonate and trace elements; The density of the denitrification and defluorination filler is 0 g / m 3 <ρ<1g / m 3 .

2. The denitrification and defluorination filler according to claim 1, characterized in that: The density of the denitrification and defluorination filler is 0.7 g / m 3 ≤ρ≤0.8g / m 3 ; Preferably, the porosity of the denitrification and defluorination filler is 40% to 55%; Preferably, the pore size of the denitrification and defluorination filler is 50 μm to 400 μm.

3. The denitrification and defluorination filler according to claim 1, characterized in that: The mass ratio of the activated carbon, the reduced sulfur source, the sodium bicarbonate, the calcium carbonate and the trace elements is (15-25): (35-55): (5-15): (18-29): (1-2).

4. The denitrification and defluorination filler according to claim 1, characterized in that: Based on the total mass of the denitrification and defluorination filler, the mass proportion of the reduced sulfur source is 35%-55%; the mass proportion of the sodium bicarbonate is 5%-15%, the mass proportion of the calcium carbonate is 18%-29%; the mass proportion of the trace elements is 1%-2%; and the mass proportion of the activated carbon is 15%-25%.

5. The denitrification and defluorination filler according to any one of claims 1 to 5, characterized in that: The reduced sulfur source includes at least one of elemental sulfur, pyrite, sodium thiosulfate, and sodium sulfide; And / or, the activated carbon includes at least one of biological activated carbon and aluminum-loaded activated carbon; Preferably, the trace elements include at least one of aluminum, magnesium, molybdenum, copper, cobalt, zinc and iron; Preferably, the trace elements include at least one of aluminum sulfate, magnesium chloride, sodium molybdate, copper sulfate, cobalt chloride, zinc sulfate, and ferric chloride; Preferably, the mass ratio of aluminum sulfate, polyaluminum chloride, magnesium chloride, sodium molybdate, copper sulfate, cobalt chloride, zinc sulfate and ferric chloride in the trace elements is (350-400):(200-300):(150-250):(4-8):(1-3):1:(8-12):(50-70).

6. A method for preparing a denitrification and defluorination filler according to any one of claims 1 to 5, characterized in that: The preparation method comprises the following steps:

1. Mixing sodium bicarbonate, activated carbon and calcium carbonate to obtain a first mixture; 2. heating the reduced sulfur source to a molten state and then mixing it with the trace elements to obtain a second mixture; 3. Evenly mix the first mixture and the second mixture, cool and shape them to obtain the denitrification and defluorination filler.

7. The preparation method according to claim 6, wherein: The particle size of the reduced sulfur source is 20-100 mesh; the particle size of the sodium bicarbonate is 20-200 mesh; the particle size of the activated carbon is 100-400 mesh; the particle size of the calcium carbonate is 200-500 mesh; Preferably, in step 2, the original sulfur source includes elemental sulfur, and heating the reduced sulfur source to a molten state includes: adding the elemental sulfur into a container, controlling the heating temperature within the range of 120° C. to 140° C. until the elemental sulfur melts, maintaining the heating temperature within the range of 100° C. to 110° C. after the elemental sulfur melts, and maintaining stirring during the heating process; Preferably, in step 2, heating the reduced sulfur source to a molten state and then mixing it with the trace elements to obtain the second mixture comprises: adding the trace elements to the melted elemental sulfur and continuously stirring for 5 minutes to obtain the second mixture; Preferably, in the step three, mixing the first mixture and the second mixture comprises: stirring the first mixture of step one and the second mixture of step two together for 5 minutes to mix them evenly.

8. Use of the denitrification and defluorination filler according to any one of claims 1 to 5 in the field of denitrification and defluorination of photovoltaic wastewater.

9. A method for denitrification and defluorination of photovoltaic wastewater, characterized in that: The denitrification and defluorination filler according to any one of claims 1 to 5 is attached with sulfur autotrophic bacteria and maintained, and then added into photovoltaic wastewater to be treated for denitrification and defluorination.

10. The preparation method according to claim 9, characterized in that The sewage to be treated has at least one of the following characteristics: (1) The fluoride ion concentration in the sewage to be purified is 15 mg / L-30 mg / L; (2) The total nitrogen concentration in the sewage to be purified is 300 mg / L-1000 mg / L; (3) The hydraulic retention time of the sewage to be purified is 2h-14h; Preferably, the curing comprises curing the denitrification and defluorination filler with sulfur autotrophic bacteria liquid for one week, and the curing conditions include: curing at 34.5°C-35.5°C, pH 6.5-7.5, and a bacterial inoculation amount of 800 mg / L.

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