CN116768357A - A polymeric sulfur compound-driven denitrification and denitrification method - Google Patents

Abstract

The invention provides a polymeric sulfur compound and a preparation method thereof, as well as a method for denitrifying sewage using the polymeric sulfur compound. The polymeric sulfur compound is prepared from elemental sulfur and oil containing unsaturated fatty acids, and the preparation method is simple. , as a filler in a biological filter, it can simultaneously carry out the heterotrophic denitrification process that generates alkalinity and the sulfur autotrophic denitrification process that generates acidity, maintaining the pH of the reaction system in a neutral range better, compared with the need for external The denitrification filter with organic carbon source and the biological filter with polymeric sulfur compound as filler do not need to add external organic carbon source, which can effectively avoid secondary pollution. At the same time, it has the advantages of high nitrate removal rate and high total nitrogen removal load.

Description

A polymeric sulfur compound-driven denitrification and denitrification method

Technical field

The invention belongs to the technical field of environmental engineering sewage treatment, and specifically relates to a polymerized sulfur compound-driven denitrification and denitrification method.

Background technique

Eutrophication of water bodies not only reduces the ornamental value of water bodies, but also harms biological survival and increases sewage treatment costs. It is a prominent phenomenon in surface water pollution problems. The increase of nitrogen in water bodies is one of the fundamental causes of eutrophication. Nitrate is the main pollutant, and various forms of nitrogen in nature can be converted into nitrate nitrogen. The national "Hygienic Standard for Drinking Water" (GB5749-2006) stipulates that the nitrate content limit in water bodies is 10 mg/L. However, in most areas of China, the nitrate nitrogen content in water bodies far exceeds this standard. Nitrate nitrogen has become a pollutant in water bodies in China. One of the main sources, when the content of NO ₃ ^- and NO ₂ ^- in drinking water is too high, it will increase the risk of water drinkers suffering from various diseases and harm human health. How to efficiently remove nitrogen is not only the focus of government departments at all levels, but also a difficulty in water environment management.

Biological denitrification has always been considered the most economical and effective method of nitrogen removal. Heterotrophic denitrification technology requires the consumption of a large amount of organic matter as a carbon source for denitrification. In view of the current water quality characteristics of low carbon to nitrogen ratio in secondary effluent, the existing heterotrophic denitrification technology The nitrification process requires the addition of an external carbon source. However, due to fluctuations in the incoming water volume and total nitrogen concentration, there are problems such as time differences in the feedback between the carbon source dosage and nitrogen concentration changes. Secondary damage caused by excessive addition of organic carbon sources may occur. Pollution increases the risk of effluent COD exceeding the standard, and the denitrification effect is extremely poor. At the same time, there are shortcomings of high alkalinity and sludge production, and the high dependence on carbon sources also leads to higher operating costs for deep nitrogen removal in heterotrophic denitrification.

Sulfur autotrophic denitrification technology does not require additional organic carbon sources to be added to low carbon to nitrogen ratio sewage, and will not cause secondary pollution of organic matter. When the COD of the incoming water reaches the standard, the effluent will not exceed the standard again. However, due to the poor solubility of elemental sulfur, microorganisms are limited in obtaining available soluble electrons from the sulfur surface, thus limiting the denitrification load of the system. Second, the sulfur-driven autotrophic denitrification reaction is an acid-generating process. When the pH is low, the activity of Thiobacillus will be inhibited, thus affecting the denitrification efficiency of the system.

Contents of the invention

Based on the above technical background, the inventors made forge ahead and found that: using polymerized sulfur compounds prepared from elemental sulfur and oil containing unsaturated fatty acids as fillers for wastewater denitrification, both sulfur and its reducing substances occurred. The autotrophic denitrification process is an electron donor, and the heterotrophic denitrification process using organic matter as a carbon source and electron donor also occurs, and polymeric sulfur compounds are more easily utilized by microorganisms than elemental sulfur. The alkalinity produced by the heterotrophic denitrification process in which the organic matter in the sulfur compound filler is the electron donor can offset part of the alkalinity consumed by the autotrophic denitrification process using sulfur as the electron donor, allowing the pH of the reaction system to be better maintained at neutral within the performance range, thereby obtaining a higher denitrification effect, and completed the present invention.

A first aspect of the present invention is to provide a polymeric sulfur compound, which is prepared from elemental sulfur and oil containing unsaturated fatty acids;

The oil containing unsaturated fatty acids is selected from one or more of rapeseed oil, sunflower oil, olive oil and soybean oil.

A second aspect of the present invention is to provide a method for preparing the polymerized sulfur compound described in the first aspect of the present invention, the preparation method comprising the following steps:

Step 1. Mix and react elemental sulfur and oil containing unsaturated fatty acids at high temperature to obtain an intermediate product;

Step 2: Clean and dry the intermediate product to obtain a polymeric sulfur compound.

The third aspect of the present invention is to provide the use of a polymeric sulfur compound according to the first aspect of the present invention or a polymeric sulfur compound prepared by the preparation method according to the second aspect of the present invention, which can be used as a filler in a biological filter. Wastewater denitrification.

A fourth aspect of the present invention is to provide a method for sewage denitrification using the polymeric sulfur compound described in the first aspect of the present invention or the polymeric sulfur compound prepared by the preparation method described in the second aspect of the present invention;

The method places polymerized sulfur compounds in a fixed bed reactor to denitrify wastewater.

Description of drawings

Figure 1 shows an upflow sulfur autotrophic denitrification fixed bed reactor according to a preferred embodiment of the present invention;

Figure 2 shows a photograph of the polymerized sulfur compound prepared in Example 1 of the present invention;

Figure 3 shows a scanning electron microscope photograph of the polymerized sulfur compound prepared in Example 1 of the present invention;

Figure 4 shows a high-magnification scanning electron microscope photograph of the polymerized sulfur compound prepared in Example 1 of the present invention;

Figure 5 shows the pH and alkalinity changes of the effluent from the denitrification systems of Example 2 and Comparative Example 1 under EBCT=1h;

Figure 6 shows the infrared spectra of polymerized sulfur compounds, elemental sulfur and rapeseed oil prepared in Example 1.

Explanation of reference numbers

1-Water tank;

2-Water pump;

3-Reaction device;

4-Water distribution support plate.

Detailed ways

The present invention will be described in detail below, and the features and advantages of the present invention will become clearer and clearer with these descriptions.

In the existing technology, elemental sulfur is often used as filler for sewage denitrification. The main microorganism that exerts the denitrification effect of elemental sulfur is the autotrophic denitrifying bacterium Thiobacillus denitrificans. However, the autotrophic denitrification reaction is an acid-producing process. process, the activity of denitrifying bacteria sulfur-oxidizing bacteria will be inhibited in an acidic environment, thereby reducing the denitrification effect. At the same time, the solubility of elemental sulfur is poor, and the microorganisms are limited in obtaining electrons from the sulfur surface, limiting the denitrification load.

A first aspect of the present invention is to provide a polymeric sulfur compound, which is prepared from elemental sulfur and oil containing unsaturated fatty acids.

The inventor found that when the polymeric sulfur compound treats wastewater, autotrophic denitrification and heterotrophic denitrification can occur simultaneously, and the carbon source can be stably released during the denitrification process. The amount of carbon source released is basically the same as the carbon source consumed in the heterotrophic denitrification process. There is no excess residual carbon source material in the wastewater after treatment. At the same time, the alkalinity consumption is small, and the pH of the reaction system can be maintained at a medium level. Within the performance range, a better denitrification effect can be achieved.

The oil containing unsaturated fatty acids is selected from one or more of rapeseed oil, olive oil, soybean oil and sunflower oil, preferably one or two types of rapeseed oil and olive oil, and more preferably rapeseed oil. Seed oil, the polymerized sulfur compound obtained from rapeseed oil as raw material has better denitrification effect and higher total nitrogen removal load.

The mass ratio of the elemental sulfur and the oil containing unsaturated fatty acids is (0.5-5):1, preferably the mass ratio is (0.7-3):1, and more preferably (0.9-1.5):1.

The mass ratio of elemental sulfur and oil containing unsaturated fatty acids will affect the sulfur content of polymerized sulfur compounds, which will in turn affect the removal effect and removal load of nitrogen in wastewater by polymerized sulfur compounds.

The mass fraction of sulfur in the polymeric sulfur compound of the present invention is 10% to 90%, preferably 20% to 80%, and more preferably 25% to 75%. Polymeric sulfur compounds with a sulfur content within the above range have a more stable denitrification effect, a higher total nitrogen removal load, and are more adaptable to volumetric load changes.

The maximum total nitrogen removal load of a biological filter using the polymerized sulfur compound as a filler can reach 1.7kgN/(m ³ ·d), the lowest effluent NO ₃ ^- -N concentration is 0.6mg/L, and the effluent NO ₂ ^- -N The minimum concentration is 0.2mg/L.

As for preparing the polymeric sulfur compound according to the present invention, it is prepared by a method including the following steps:

Step 1. Mix and react elemental sulfur and oil containing unsaturated fatty acids at high temperature to obtain an intermediate product;

Step 2: Clean and dry the intermediate product to obtain a polymeric sulfur compound.

A second aspect of the present invention is to provide a method for preparing the polymerized sulfur compound described in the first aspect of the present invention, the preparation method comprising the following steps:

Step 1. Mix and react elemental sulfur and oil containing unsaturated fatty acids at high temperature to obtain an intermediate product;

Step 2: Clean and dry the intermediate product to obtain a polymeric sulfur compound.

This step is described and illustrated in detail below.

Step 1. Mix and react elemental sulfur and oil containing unsaturated fatty acids at high temperature to obtain an intermediate product.

The mixing is preferably performed in a reaction kettle, and more preferably, the elemental sulfur is first heated and melted, and then the oil containing unsaturated fatty acid is added to the elemental sulfur.

The oil containing unsaturated fatty acids is added by dropwise addition. During the dripping process, the oil is continuously stirred to form a two-phase mixture of elemental sulfur and the oil containing unsaturated fatty acids.

The mixing reaction temperature is 160 to 200°C, preferably 170 to 190°C, and more preferably 180°C. Keep stirring and mixing at this temperature until an elastic solid is obtained, which is the intermediate product.

The reaction time is 10 to 60 minutes, preferably 15 to 45 minutes, more preferably 20 minutes.

The oil containing unsaturated fatty acids is selected from one or more of rapeseed oil, sunflower oil, olive oil and soybean oil, preferably one or both of rapeseed oil and olive oil, and more preferably rapeseed oil. seed oil.

The mass ratio of the elemental sulfur and the oil containing unsaturated fatty acids is (0.1-10):1, preferably the mass ratio is (0.2-5):1, and more preferably (0.3-4):1.

The polymerized sulfur compound prepared within the above mass ratio range has a suitable sulfur content and can be used as a filler in a biological filter to effectively denitrify sewage. Compared with elemental sulfur (rhomboidal sulfur), its total nitrogen removal load is high. More adaptable to changes in volume load.

Step 2: Clean and dry the intermediate product to obtain a polymeric sulfur compound.

The intermediate product is cut into particles, and the particle size is preferably 0.1 to 20 mm, more preferably 0.2 to 12 mm.

The specific surface area of particles is related to their particle size. The specific surface area of polymerized sulfur compounds within the above particle size range is moderate and can fully contact with wastewater to increase the denitrification removal load.

Clean the cut particles and soak them in an alkaline solution, preferably a 0.1 mol/L NaOH solution, to remove residual hydrogen sulfide.

Mechanical stirring is performed continuously during the soaking process, and the stirring time is 60 to 120 minutes, preferably 90 minutes. Fully remove residual hydrogen sulfide.

After soaking, filter out the alkaline solution, rinse the separated particles with water, and repeat the operation 2 to 5 times.

After cleaning, dry, preferably air-drying at room temperature, and the drying time is 20 to 30 hours, preferably 24 hours.

The polymerized sulfur compound prepared by the present invention can stably release carbon sources during the denitrification process and provide electron donors for the heterotrophic denitrification process. Tests have found that after the denitrification process, the sulfur on the polymerized sulfur compound filler The alcohol content has increased, indicating that the polymeric sulfur compound filler itself can participate in the denitrification process, turning the -[S] _n group of the long-chain polysulfide connected to the C atom in its structure into a sulfhydryl group (-SH). Thiols are generated. At the same time, it was found that polymeric sulfur compounds are more easily utilized by microorganisms than the ring structure of elemental sulfur.

The third aspect of the present invention is to provide the use of a polymeric sulfur compound according to the first aspect of the present invention or a polymeric sulfur compound prepared by the preparation method according to the second aspect of the present invention, which can be used as a filler in a biological filter. Wastewater denitrification.

The fourth aspect of the present invention is to provide a method for denitrifying wastewater using the polymeric sulfur compound described in the first aspect of the present invention or the polymeric sulfur compound prepared by the preparation method described in the second aspect of the present invention.

The method places polymerized sulfur compounds in a fixed bed reactor to denitrify wastewater.

The fixed bed reactor is shown in Figure 1. The fixed bed reactor is made of acrylic plates.

The inventor found that when the polymeric sulfur compound of the present invention is used as a filler in a fixed bed reactor, during the sewage treatment process, heterotrophic denitrifying bacteria, such as Stenotrophomonas and Pseudomonas aeruginosa, appear in the polymer filler. Monospora, not only the autotrophic denitrification process using sulfur and its reducing substances as electron donors, but also the heterotrophic denitrification process using organic matter as the carbon source and electron donor occurs, and Thiobacillus denitrificans The abundance increases to twice that of the elemental sulfur filler, and the population advantage is greater.

The fixed bed reactor includes a water tank 1, a water pump 2 and a reaction device 3. As shown in Figure 1, the water pump 2 is located between the water tank 1 and the reaction device 3. The water tank 1, the reaction device 3 and the water pump 2 are connected through pipelines. The water tank 1 is used to store sewage, and the water pump 2 is used to pump the water in the water tank 1 into the reaction device 3.

The sewage enters through the pipeline from the lower part of the reaction device and flows out through the upper part of the reaction device. Before the sewage is pumped into the reaction device, nitrogen is preferably used to blow off the dissolved oxygen in the sewage, and the lid is sealed to effectively remove the bed. The nitrogen in the layer creates an anoxic environment for the growth of microorganisms and ensures the normal operation of the reactor.

The lower part of the reaction device 3 is provided with a water inlet and a water distribution support plate 4. The sewage enters the reaction device from the water inlet and reaches the water outlet through the filler from bottom to top.

Small holes are evenly distributed on the water distribution support plate. The water distribution support plate 4 is used to support the filler. The distributed small holes are used to allow the sewage to be treated to reach the filler layer through the support plate.

Preferably, the diameter of the small hole is 0.5-2 mm, preferably 1 mm.

The diameter of the reaction device 3 is 30 to 50 mm, preferably 40 mm. The reactor height is 170-200mm, preferably 180-190mm.

According to a preferred embodiment of the present invention, the ratio of the volume of the polymerized sulfur compound filler to the total volume of the reaction device 3 is 1: (2-3), preferably 1: (2.5-2.8).

The volume of the polymeric sulfur compound used as filler in the present invention will affect the denitrification effect of sewage. If too little filler is used, the denitrification effect of sewage will be poor. If the filler is used too much, the cost of sewage treatment will be increased.

The sewage to be treated is pumped into the reaction device by a water pump. The flow rate of the sewage is 0.19 to 6.8 mL/min, preferably 0.5 to 2.26 mL/min, and more preferably 0.7 to 2 mL/min.

The time for the sewage to be treated to pass through the reaction device is 5 minutes to 10 hours, the preferred time is 10 minutes to 8 hours, and the more preferred time is 10 minutes to 6 hours.

The flow rate of sewage is too fast or the time it takes to pass through the reaction device is too short. The contact time between the denitrifying bacteria in the system and the nitrate nitrogen in the water body is reduced. The sewage fails to fully contact the filler. The denitrification performance in the system is reduced, and the effluent water The concentration of nitrate nitrogen increases significantly, resulting in poor denitrification effect. At the same time, too fast a flow rate will also affect the microorganisms in the reactor, causing the microorganisms to fall off the surface of the filler and be discharged with the water flow, resulting in a decrease in denitrification efficiency and a decrease in the flow rate of sewage. If it is too slow or the time it takes to pass through the reaction device is too long, the water treatment time will be extended, which is not conducive to improving the efficiency of sewage treatment.

The beneficial effects of the present invention are:

(1) Compared with sulfur packed bed biological filters, in addition to the ability to intercept suspended pollutants, the polymeric sulfur compound of the present invention can also be used as a filler in biological filters to simultaneously perform heterotrophic denitrification that generates alkalinity. As well as the sulfur autotrophic denitrification process that generates acidity, the amount of carbon source released is basically the same as the carbon source consumed by the heterotrophic denitrification process. There is no excessive residual carbon source material in the effluent, effectively avoiding secondary pollution;

(2) The polymeric sulfur compound packed bed biological filter of the present invention is more adaptable to changes in volume load and has a more stable denitrification effect;

(3) The maximum total nitrogen removal load of the biological filter in which the polymeric sulfur compound of the present invention is used as filler can reach 1.7kgN/(m ³ ·d), and the optimal EBCT is 1h. Under these conditions, the effluent NO ₃ ^- -N (Nitrate nitrogen refers to the nitrogen element contained in nitrate) The minimum concentration is 0.6mg/L, and the minimum concentration of NO ₂ ^- -N is 0.2mg/L;

(4) In the process of sewage treatment, polymeric sulfur compounds can stably release carbon sources and consume less alkalinity. There is no need to add alkali substances in the sewage treatment process.

Example

The present invention will be further described below through specific examples. These examples are only for illustrating the present invention and are not intended to limit the scope of the present invention.

Example 1

Add 20g of elemental sulfur (rhomboidal sulfur, composed of S ₈ cyclic molecules) into the reactor, stir and melt, then heat to 180°C, then add 20g of rapeseed oil drop by drop, stirring continuously during the period, so that the sulfur oil forms two phase mixture, continue stirring for 10 minutes, mix the sulfur oil thoroughly to form a brown viscous liquid, continue to heat at 180°C for 20 minutes, and stir continuously with a glass rod, and finally obtain an elastic solid.

Take the solid out of the reaction kettle, cut it into particles with diameters ranging from 0.2mm to 12mm (average diameter is 4mm), soak in 0.1mol/L NaOH solution, stir at room temperature for 90 minutes, remove residual hydrogen sulfide, and filter Then rinse the separated particles with 50 mL of deionized water, repeat the operation three times, and air-dry the particles at room temperature for 24 hours to obtain the polymerized sulfur compound, whose photo is shown in Figure 2.

Example 2

The fixed bed reactor is made of acrylic plates. The actual finished product is shown in Figure 1. The diameter of the main body of the device is 40mm, the height is 186mm, the total volume is 233mL, the carrier filling volume is 85mL, and the filler is the polymerized sulfur compound prepared in Example 1. The lower part of the device is equipped with a water inlet and a water distribution support plate. Small holes with a diameter of 1 mm are opened on the support plate to distribute water evenly. The system inoculation sludge is taken from the activated sludge (10g TSS/L) in the secondary sedimentation tank of Beijing Gaobeidian Wastewater Treatment Plant. After being placed in a sealed container for a long time, it becomes anaerobic activated sludge. It is filtered with a filter and used as seed sludge. Artificial water distribution simulates sewage, and the water quality is shown in Table 1 below:

Table 1

Pass the sewage through the reaction device in the fixed bed reactor, its flow rate in the reaction device is 1.13mL/min, and the time it takes to pass through the reaction device is 1 hour.

Example 3

The polymerized sulfur compound was prepared in a manner similar to Example 1, the only difference being that: 10g of elemental sulfur (rhombic sulfur, composed of S ₈ cyclic molecules) was added to the reaction kettle, stirred and melted, and then heated to 180°C. , then add 30g rapeseed oil drop by drop.

Example 4

The polymerized sulfur compound was prepared in a manner similar to Example 1, the only difference being that: 30g of elemental sulfur (rhombic sulfur, composed of S ₈ cyclic molecules) was added to the reaction kettle, stirred and melted, and then heated to 180°C. , then add 10g rapeseed oil drop by drop.

Example 5

Sewage denitrification is carried out in a manner similar to Example 2, the only difference being that the filler is the polymerized sulfur compound prepared in Example 3.

Example 6

Sewage denitrification was carried out in a manner similar to Example 2, the only difference being that the filler was the polymerized sulfur compound prepared in Example 4.

Example 7

Sewage denitrification was carried out in a similar manner to Example 2, the only difference being that the time for passing through the reaction device was 6 hours.

Example 8

Denitrification of sewage was carried out in a similar manner to Example 2, the only difference being that the time for passing through the reaction device was 0.5 h.

Example 9

Denitrification of sewage was carried out in a similar manner to Example 2, the only difference being that the time for passing through the reaction device was 15 minutes.

Example 10

Denitrification of sewage was carried out in a similar manner to Example 2, the only difference being that the time for passing through the reaction device was 10 minutes.

Comparative ratio

Comparative example 1

Sewage treatment was carried out in a manner similar to Example 2, the only difference being that the filler in the fixed bed reactor was elemental sulfur (rhombic sulfur, composed of S ₈ cyclic molecules), which was purchased from Sinopec Qilu Petrochemical Company , spherical in shape, with a particle size of 3 to 6 mm.

Experimental example

Experimental example 1 SEM test

The polymerized sulfur compound prepared in Example 1 was subjected to a scanning electron microscope test, and the test results are shown in Figures 3 and 4.

As can be seen from Figure 3, the surface structure of the polymeric sulfur compound filler is loose and layered, which can provide suitable attachment points and a good growth environment for microbial flora, indicating that the polymeric sulfur compound filler can be a good carrier for biofilm growth and medium

Figure 4 is a scanning electron microscope photo magnified 20,000 times. From Figure 4, it can be clearly seen that a large number of microorganisms are attached and grown on the polymeric sulfur compound filler. The sticky substances secreted by the microbial flora bind it closely to the polymeric sulfur compound filler. stick together to form a dense biofilm. At the same time, it can be seen that the shapes of microorganisms attached to the surface of the polymeric sulfur compound filler are mainly spherical and rod-shaped. It is proved that the polymeric sulfur compound filler can successfully attach a large number of functional bacteria, including both heterotrophic and denitrifying functional bacteria and autotrophic denitrifying functional bacteria. It shows that the polymeric sulfur compound filler can not only be used as an electron donor in the denitrification process, but also can be used as a carrier and medium for the growth and attachment of microbial flora.

Experimental Example 2 Nitrate Nitrogen Measurement

The nitrate nitrogen in the incoming and outgoing water was measured. The nitrate nitrogen was measured using an ion chromatograph, model 883Basic ICPlus, manufactured by Swiss Metrohm China Co., Ltd., and the total nitrogen removal load was: total nitrogen in the incoming water × total water volume/reaction volume. The measurement results are shown in Table 2:

Table 2

Influent nitrate nitrogen content Effluent nitrate nitrogen content Nitrate nitrogen removal rate Example 2 20.7mg/L 0.6mg/L 97.1% Example 7 21.955mg/L 0.51mg/L 97.68% Example 8 20.267mg/L 0.2745mg/L 98.65% Example 9 19.079mg/L 1.675mg/L 91.22% Example 10 19.211mg/L 1.699mg/L 91.16% Comparative example 1 19.1mg/L 4.7mg/L 75.3%

It can be seen from Table 2 that using the polymeric sulfur compound described in Example 1 of the present invention for denitrification of sewage can significantly reduce the nitrate nitrogen content of the effluent. According to the total nitrogen removal load formula, the total nitrogen removal load of Example 2 is 1.7kg·N/(m ³ ·d), and the total nitrogen removal load of Comparative Example 1 is 0.6kg·N/(m ³ ·d). It shows that the use of the polymeric sulfur compound of the present invention for denitrification of sewage has a higher total nitrogen removal load.

Comparing Examples 2 to 10, it can be seen that the time for the sewage to pass through the reaction device will affect the removal rate of nitrate nitrogen. When the time for the sewage to pass through the reaction device is 0.5 h, the removal rate of nitrate nitrogen in the sewage is the highest.

Experimental Example 3 System Outlet Water pH and Alkalinity Change Test

The pH value of the water body will change the charged state of the substrate and microbial enzymes, thereby affecting the activity of microbial enzymes and the degradation of the substrate by the microbial community. The pH of the suitable reaction system for denitrifying bacteria is in the range of 7-8.

The specific testing process of effluent pH and alkalinity is as follows: the filler is elemental sulfur as described in Example 2 and Comparative Example 1, and the effluent pH and alkalinity are tested under the condition that the time it passes through the sewage treatment device is 1 hour. During the sewage treatment process, the pH of the incoming water is maintained at 7.9±0.1, and the alkalinity is 212±6mg/L. The test results are shown in Figure 5.

The pH of the system effluent in Comparative Example 1 gradually decreased from 7.9±0.1 to 6.3±0.1, and the alkalinity was 111±3mg/L. This is because the sulfur autotrophic denitrification process is a process that consumes alkalinity. The pH of the effluent from the polymeric sulfur compound system in Example 2 decreased from 7.9±0.1 to 6.6±0.1, and the alkalinity was 151±20 mg/L. Compared with Comparative Example 1, the pH and alkalinity of the system effluent are higher, which shows that the alkalinity generated by the heterotrophic denitrification process inside the system offsets part of the acid generated by the sulfur autotrophic denitrification process, and self-balance can be achieved.

Experimental Example 4 Infrared Test

In order to study the correlation between the polymeric sulfur compound filler and the chemical structural functional groups of rapeseed oil, the Fourier transform infrared spectrum test and analysis of the polymeric sulfur compound filler prepared in Example 1 and rapeseed oil were carried out. The scanning wave number range was 3250-500cm. ^-1 . The test results are shown in Figure 6.

As can be seen from Figure 6, the peak of the polymerized sulfur compound filler at 1745cm ^-1 is generated by the stretching vibration of the C=O chemical bond, and the saturated CH stretching vibration peaks appear at 2925cm ^-1 and 2854cm ^-1 . These are consistent with the infrared spectrum of rapeseed oil. The unsaturated hydrocarbon stretching vibration peaks of C=CH and C=C appear respectively at 3010cm ^-1 and 1650cm ^-1 in the infrared spectrum of rapeseed oil, but are missing in the infrared spectrum of the polymerized sulfur compound filler. This is because It shows that sulfur reacts with olefins to form polysulfides.

Infrared spectroscopy analysis of polymeric sulfur compounds shows that polymeric sulfur compounds synthesized from rapeseed oil and elemental sulfur have the characteristics of chemical bonds of the two raw materials.

The present invention has been described in detail above with reference to specific embodiments and exemplary examples. However, these descriptions should not be construed as limitations of the present invention. Those skilled in the art understand that without departing from the spirit and scope of the invention, various equivalent substitutions, modifications or improvements can be made to the technical solution and its implementation of the invention, and these all fall within the scope of the invention. The scope of protection of the present invention is determined by the appended claims.

Claims (10)

1. A polymerized sulfur compound, characterized in that the polymerized sulfur compound is produced from elemental sulfur and an unsaturated fatty acid-containing oil;

the unsaturated fatty acid-containing oil is one or more selected from rapeseed oil, sunflower seed oil, olive oil and soybean oil.

2. The polymerized sulfur compound according to claim 1, wherein the mass fraction of sulfur in the polymerized sulfur compound is 10% to 90%.

3. The polymerized sulfur compound according to claim 1,

the maximum total nitrogen removal load of the biological filter with the polymer sulfur compound as the filler can reach 1.7 kgN/(m) ³ D), effluent NO ₃ ^- The minimum concentration of N is 0.6mg/L, and the NO in the effluent water ₂ ^- The concentration of N is at least 0.2mg/L.

4. A process for producing the sulfur compound in a polymerized state as defined in any one of claims 1 to 3, characterized by comprising the steps of:

step 1, mixing elemental sulfur and oil containing unsaturated fatty acid at high temperature for reaction to obtain an intermediate product;

and step 2, cleaning and drying the intermediate product to obtain the polymerized sulfur compound.

5. The method according to claim 4, wherein in step 1, the mass ratio of elemental sulfur to the unsaturated fatty acid-containing oil is (0.1 to 10): 1.

6. the process according to claim 4, wherein in step 1, the mixing reaction temperature is 160 to 200 ℃.

7. The process according to claim 4, wherein in step 2, the intermediate product is cut into granules, preferably having a particle size of 0.1 to 20mm.

8. Use of a polymeric sulfur compound according to one of claims 1 to 3 or a polymeric sulfur compound produced by the production process according to one of claims 4 to 7 as a filler for biofilters for sewage denitrification.

9. A method for denitrification of sewage using a polymeric sulfur compound, characterized in that the polymeric sulfur compound is the polymeric sulfur compound according to any one of claims 1 to 3 or the polymeric sulfur compound produced by the production method according to any one of claims 4 to 7;

the method is to place the polymerized sulfur compound in a fixed bed reactor for sewage denitrification.

10. The sewage denitrification method according to claim 9, wherein the fixed bed reactor comprises a water tank (1), a water pump (2) and a reaction device (3);

the lower part of the reaction device (3) is provided with a water inlet and a water distribution supporting plate (4), and the ratio of the volume of the polymeric sulfur compound filler to the total volume of the reaction device is 1: (2-3).