Sulfur denitrification agent using sulfur-containing wastes

Abstract

The present invention relates to a sulfur denitrification agent using sulfur-containing wastes, which can be recycled as a denitrification agent for water treatment by using discarded mine drainage sludge, sulfur-containing wastes generated in a hydrogen sulfide removal process, and the like. The sulfur denitrification agent using sulfur-containing wastes of the present invention includes, on the basis of the total weight, 50-70 wt% of mine drainage sludge, 15-30 wt% of waste iron sulfide generated in a hydrogen sulfide removal process, and 15-30 wt% of sulfur powder, wherein as the sulfur powder, sulfur generated in a desulfurization process is used, and the sulfur generated in the desulfurization process is sulfur sludge generated in the desulfurization process using iron chelate (Fe-chelate) or sulfur-containing wastes generated in a bio-sulfur treatment process.

Description

sulfur denitrification agent using sulfur-containing waste

[0001] The present invention relates to a sulfur denitrifying agent using sulfur-containing waste that can be recycled as a denitrifying agent for water treatment by utilizing discarded mine drainage sludge, sulfur-containing waste generated in hydrogen sulfide removal processes, and sulfur components.

[0002] Wastewater treatment plants, anaerobic digestion leaching treatment plants, and leachate treatment plants apply many processes to remove nitrogen compounds contained in wastewater. Among them, nitrate nitrogen (NO3) in water - Since N) is a harmful substance that causes infantile cyanosis and cancer, the amount included in discharged water is strictly managed in accordance with rigorous water quality standards not only domestically but also globally.

[0003] Conventional biological denitrification processes use ammonia nitrogen (NH4) through aeration. + -N) is nitrate nitrogen (NO3 - After converting to -N, a heterotrophic denitrification process is performed using the plant's own organic matter as an electron donor, or by additionally injecting an external carbon source (such as methanol) when the C / N ratio is low due to a lack of plant organic matter.

[0004] Microorganisms use an external carbon source as an electron donor to produce nitrate nitrogen (NO3 - Nitrate nitrogen is finally removed by reducing -N) to nitrogen gas (N2). Heterotrophic denitrification has the disadvantages of the continuous costs incurred in using external carbon sources (such as methanol) and the carbon dioxide generated as the external carbon sources are converted into carbon dioxide, which accelerates global warming, and the generation of a large amount of sludge due to the use of organic matter is also pointed out as a problem.

[0005] On the other hand, the aforementioned autotrophic denitrification process is characterized by the fact that it does not require the injection of organic matter, as it uses inorganic matter (sulfur) as an electron donor instead of organic matter during the denitrification reaction. In autotrophic denitrification, sulfur-oxidizing denitrifying microorganisms convert various types of sulfur compounds into sulfate ions (SO4). 2- While oxidizing to ) simultaneously NO3 -It utilizes the principle of converting -N to N2(g). In other words, it uses denitrifying bacteria, such as sulfur-oxidizing denitrifying microorganisms like Thiobacillus denitrificans and Thiomicrospira denitrificans, to convert various types of sulfur compounds into sulfate ions (SO4). 2- The denitrification reaction proceeds while oxidizing to ). Since sulfur-reducing denitrifying microorganisms are autotrophic microorganisms, they do not require an external carbon source, and can economically and stably induce denitrification in wastewater with a low C / N ratio without adding methanol.

[0006] Accordingly, a technology was developed to contribute to a circular economy by recycling waste generated from the hydrogen sulfide (H2S) removal process for water treatment, utilizing autotrophic denitrification.

[0007] The objective of the present invention is to provide a sulfur denitrifying agent using sulfur-containing waste that can be recycled as a denitrifying agent for water treatment using discarded mine drainage sludge and sulfur-containing waste generated in the hydrogen sulfide removal process.

[0008] The sulfur denitrifying agent using sulfur-containing waste according to the present invention comprises, based on the total weight, 50 to 70 weight percent of mine drainage sludge, 15 to 30 weight percent of waste iron sulfide generated in a hydrogen sulfide removal process, and 15 to 30 weight percent of sulfur powder, wherein the sulfur powder is sulfur generated in a desulfurization process, and the sulfur generated in the desulfurization process is sulfur sludge generated in a desulfurization process using iron chelate (Fe-chelate) or sulfur-containing waste generated in a bio-sulfur treatment process.

[0009] Preferably, the mine drainage sludge is manufactured by the steps of: supplying mine drainage to a storage tank to store it while separating and settling solid foreign substances contained in the mine drainage; drying the settled mine drainage sludge to remove moisture to achieve a moisture content of 60 to 80%; and filtering the mine drainage sludge with improved moisture content through a sieve of a predetermined size to homogenize it into mine drainage sludge with a size smaller than or equal to a standard size.

[0010] Preferably, the waste iron sulfide generated in the hydrogen sulfide removal process is manufactured by the following steps: immersing the iron hydroxide-based waste desulfurizing agent, which has been destroyed by hydrogen sulfide in a desulfurization tower, in water to remove excess hydrogen sulfide and foreign substances attached to the surface of the waste desulfurizing agent while heating and stabilizing the waste iron sulfide; drying the stabilized waste iron sulfide to remove moisture; and homogenizing the dried waste iron sulfide to have a size smaller than or equal to a standard size.

[0011] The sulfur denitrifying agent of the present invention, utilizing sulfur-containing waste, can be recycled as a denitrifying agent for water treatment by using discarded mine drainage sludge, waste desulfurizing agents generated in hydrogen sulfide removal processes and landfilled, and sulfur generated in desulfurization processes, and has the advantage of contributing to a circular economy.

[0012] In addition, since the sulfur denitrifying agent contains a high concentration of sulfur due to the sulfur in the waste desulfurization agent and sulfur sludge, sulfur denitrifying microorganisms can utilize it as an electron donor for the sulfur denitrification reaction. Furthermore, because it maintains the characteristics of an adsorbent, it has a large specific surface area, which is favorable for the attachment and growth of sulfur denitrifying bacteria, resulting in the advantage of excellent denitrification efficiency.

[0013] FIG. 1 is a schematic diagram of the manufacturing process of a sulfur denitrifying agent using sulfur-containing waste according to the present invention.

[0014] FIG. 2(A) shows the results of analyzing the nitrate nitrogen concentration in the column effluent of a sulfur denitrifying agent prepared according to an embodiment of the present invention, and FIG. 2(B) shows the results of analyzing the nitrite nitrogen concentration in the column effluent.

[0015] FIG. 3(A) shows the results of analyzing the nitrate nitrogen concentration in the effluent of the reaction tank of the sulfur denitrification agent prepared according to an embodiment of the present invention, and FIG. 3(B) shows the results of analyzing the nitrite nitrogen concentration in the effluent of the reaction tank.

[0016] Figure 4 is an XRF result analysis table of a sulfur denitrifying agent prepared according to an embodiment of the present invention.

[0017] Hereinafter, embodiments of the present invention will be described with reference to the attached drawings.

[0018] The sulfur denitrifying agent using sulfur-containing waste according to the present invention comprises mine drainage sludge, waste iron sulfide generated in the hydrogen sulfide removal process, and sulfur powder.

[0019] Mine drainage sludge is used as a binder for sulfur denitrification agents. It is preferable that the mine drainage sludge be manufactured by the following steps: a step of separating solid foreign substances contained in the mine drainage while storing the mine drainage in a storage tank; a step of removing moisture by drying the settled mine drainage sludge to achieve a moisture content of 60-70%; and a step of homogenizing the mine drainage sludge with improved moisture content by filtering it through a sieve of a predetermined size to obtain a size smaller than a standard size. At this time, it is preferable to remove moisture from the mine drainage sludge by hot air drying or natural drying at room temperature, and it is preferable to homogenize the mine drainage sludge to obtain a size of approximately 20-40 mesh.

[0020] Mine drainage sludge is used at 50 to 80 weight percent based on the total weight. If less than 50 weight percent, there may be a problem with maintaining the shape during molding of the denitrifying agent produced, and also a problem with maintaining a consistent shape after molding. If more than 80 weight percent, there is a problem with the denitrification performance of the denitrifying agent being lowered.

[0021] Waste iron sulfide generated in the hydrogen sulfide removal process uses broken-down iron hydroxide-based waste desulfurization agents because iron hydroxide (Fe(OH)3) has a very high reactivity with hydrogen sulfide.

[0022] It is preferable to produce waste iron sulfide powder by immersing the iron hydroxide-based waste desulfurizing agent, which has been destroyed by hydrogen sulfide in a desulfurization tower, in water to remove excess hydrogen sulfide and foreign substances attached to the surface of the waste desulfurizing agent while stabilizing the iron sulfide, drying it to remove moisture, and then grinding it to a certain size. It is preferable to use the waste desulfurizing agent powder by homogeneously grinding the destroyed waste desulfurizing agent to have a mesh size of about 20 to 40.

[0023] These iron hydroxide-based waste desulfurizing agents contain large amounts of iron sulfides, such as FeS or Fe2S3, which are produced by the reaction of iron hydroxide (Fe(OH)3) with hydrogen sulfide; the sulfates separated from the iron sulfides in the iron hydroxide-based waste desulfurizing agents are used as electron donors in the sulfur denitrification reaction, and the sulfate ions (SO4) generated as a byproduct 2- ) disulfide (HS) by sulfur-reducing bacteria - After being converted into (see Reaction Equation 1), hydrogen ions (H) in water + When converted into hydrogen sulfide gas (H2S) by reacting with ) during the denitrification process, the hydrogen sulfide reacts again with the iron hydroxide from which sulfur was consumed, thereby not only removing the hydrogen sulfide odor but also extending the denitrification lifespan of the sulfur denitrifier by causing internal circulation of sulfur (see Reaction Equation 2).

[0024] [Reaction Equation 1]

[0025] 10FeS + 12NO3 - + 4H2O → 6N2 + 10SO4 2- + 10Fe(OH)3 + 8H +

[0026] SO4 2- + 9H + → HS - + 4H2O or Organics + SO4 2- → 2HCO3 - + HS -

[0027] [Reaction Equation 2]

[0028] HS- + H + → H2S

[0029] 3H2S + 2Fe(OH)3→ FeS + S + H2O

[0030] Waste iron sulfide generated in the hydrogen sulfide removal process is used at 15 to 30 weight percent based on the total weight. If less than 15 weight percent, there is a problem with the denitrification performance of the denitrifying agent being low, and also a problem with maintaining a consistent shape after molding. If more than 30 weight percent, there is a problem with the lifespan of the denitrifying agent being shortened because the elemental sulfur is insufficient by the excess amount.

[0031] Sulfur powder is used to provide sulfur ions consumed during the denitrification process. Sulfur can be obtained by using sulfur powder generated in a desulfurization process or by using elemental sulfur powder. In particular, it is preferable that the sulfur generated in the desulfurization process be sulfur sludge from a desulfurization process using iron chelates (Fe-chelates) or sulfur-containing waste from a bio-sulfur treatment process. Sulfur sludge from a wet desulfurization process using iron chelates or sulfur-containing waste from a bio-sulfur treatment process has a moisture content of approximately 60–85%, and most of the solid content consists of sulfur. Additionally, it is preferable to use sulfur that has been homogeneously ground to have a mesh size of approximately 20–40.

[0032] Sulfur powder is used in an amount of 15 to 30% by weight based on the total weight. If less than 15% by weight, there is a problem with the denitrification performance of the generated denitrifying agent being low, and if more than 30% by weight, there is a problem with the generation of bad odors due to the reduction of hydrogen sulfide (H2S) by sulfur-reducing bacteria.

[0033] A sulfur denitrifying agent is manufactured by uniformly mixing such mine drainage sludge powder, waste iron sulfide generated in the hydrogen sulfide removal process, and sulfur, placing the mixture into a mold of a predetermined shape, and molding it into a pellet shape, a cylindrical shape, etc.

[0034] Since the sulfur denitrifying agent produced in this way contains a high concentration of sulfur due to the sulfur in the waste desulfurization agent and sulfur sludge, sulfur denitrifying microorganisms can utilize it as an electron donor for the sulfur denitrification reaction. Additionally, because it maintains the characteristics of an adsorbent, it has a large specific surface area, which is favorable for the attachment and growth of sulfur denitrifying bacteria, resulting in excellent denitrification efficiency.

[0035] Hereinafter, experimental examples of the present invention will be described.

[0036] <Example>

[0037] After the sedimentation of solid foreign matter was completed, mine drainage sludge containing approximately 150 ppm of iron was dried to a moisture content of 60–70%, 30 g of the mine drainage sludge was mixed with 10 g of waste iron sulfide generated in the hydrogen sulfide removal process and 10 g of sulfur sludge generated in the desulfurization process using iron chelate (Fe-chelate). The mixture was then extruded into pellets and dried to produce a sulfur denitrifying agent using sulfur-containing waste.

[0038] <Treatment of Landfill Leachate Using Sulfur Denitrification Agents and Analysis of Nitrogen Content in Column Effluent>

[0039] Biologically and chemically treated leachate (NO3) generated from a landfill is passed through a peristaltic pump at the bottom of a column filled with the sulfur denitrifying agent of the manufactured example. - -N 35 ~ 66 mg / L, NO2 - -N (14 ~ 29 mg / L) was injected, and the trend of changes in nitrate and nitrite nitrogen concentrations in the column effluent was analyzed by operating the column in an upward flow continuous manner with the Empty Bed Contact Time (EBCT) varied from 8 hours to 4 hours.

[0040] The analysis of changes in the above nitrate and nitrite concentrations was performed using the HACH Spectrophotometer method. The HACH DR 3900 model was used, and the analysis of nitrate was performed using Method 10020 Nitrate HR, while the analysis of nitrite was performed using Method 10019 Nitrite LR.

[0041] Figure 2(A) shows the results of analyzing the nitrate nitrogen concentration in the column effluent, and Figure 2(B) shows the results of analyzing the nitrite nitrogen concentration in the column effluent.

[0042] As shown in the graph of the nitrate nitrogen concentration in the column effluent of Figure 2(A), when the EBCT of the sulfur denitrifying agent of the example was 8 hours, the activity of the sulfur denitrifying microorganisms was low for the first 4 days, resulting in high nitrate nitrogen concentration and low treatment rate in the effluent; however, the treatment rate increased from the 5th day of operation, and even when the EBCT was lowered to 4 hours, a nitrate nitrogen treatment rate of over 80% was observed.

[0043] In addition, as shown in the nitrite nitrogen graph of the column effluent in Fig. 2(B), the sulfur denitrifying agent of the example showed a low treatment rate due to the low activity of sulfur denitrifying microorganisms during the first 2 days when the EBCT was 8 hours, but showed a treatment rate of 90 to 100% from the 3rd day of operation. When the EBCT was lowered to 4 hours, it showed a treatment efficiency of about 90% for 2 days, but it was confirmed that the treatment rate was maintained at 60 to 70% when the nitrite nitrogen concentration of the leachate treatment water was injected at a high concentration of about 30 mg / L.

[0044] <Treatment of Wastewater Treatment Plant Effluent Using Sulfur Denitrification Agents and Analysis of Nitrogen Content in Reactor Effluent>

[0045] The effluent from a secondary sedimentation tank of a sewage treatment plant was injected into the bottom of a 25 L upward-flow reactor filled with the sulfur denitrifying agent of the prepared example through a peristaltic pump, and the trend of changes in the concentrations of nitrate nitrogen and nitrite nitrogen in the reactor effluent was analyzed by operating the reactor in a continuous upward-flow manner with the Empty Bed Contact Time (EBCT) varied from 8 hours to 1.5 hours.

[0046] The analysis of changes in the above nitrate and nitrite concentrations was performed using the HACH Spectrophotometer method. The HACH DR 3900 model was used, and the analysis of nitrate was performed using Method 10020 Nitrate HR, while the analysis of nitrite was performed using Method 10019 Nitrite LR.

[0047] Figure 3(A) shows the results of analyzing the nitrate nitrogen concentration in the effluent of the reactor, and Figure 3(B) shows the results of analyzing the nitrite nitrogen concentration in the effluent of the reactor.

[0048] As shown in the graph of the nitrate nitrogen concentration in the effluent of the reactor in Figure 3(A), when the EBCT of the sulfur denitrifying agent of the example was 8 hours, the activity of the sulfur denitrifying microorganisms was low during the first day, so nitrate nitrogen in the effluent was discharged and the treatment rate was about 80%, but the treatment rate increased from the second day of operation, and even when the EBCT was lowered to 4 hours and 1.5 hours, a nitrate nitrogen treatment rate of about 90% was observed.

[0049] In addition, as shown in the graph of nitrite nitrogen concentration in the reactor effluent in Fig. 3(B), when the EBCT of the sulfur denitrifying agent of the example was 8 hours, nitrite nitrogen was not treated and effluent was discharged during the first day due to the low activity of sulfur denitrifying microorganisms, but a treatment rate of over 90% was observed from the second day of operation. It was confirmed that a treatment efficiency of over 90% was consistently maintained even when the EBCT was lowered to 4 hours and 1.5 hours.

[0050] <XRF를 이용한 황탈질제 성상 분석>

[0051] X-ray Fluorescence (XRF) analysis was performed to confirm the sulfur, iron, and other properties of the sulfur denitrifying agent of the above-prepared example, and is shown in Fig. 4. For the XRF analysis, the above-prepared example was ground to homogenize the particle size to 350 μm, 5 g of the sample was taken, and the quantity and quantitative analysis of specific components of the example were performed using the S8 Tiger (Bruker AXS) model.

[0052] In the X-ray fluorescence analysis report of the sulfur denitrifying agent in the above example, sulfur oxides (SO3) and iron oxides (Fe2O3) account for approximately 88% of the total components, of which sulfur oxides account for 72% and iron oxides account for approximately 16%. The numbers expressed in the XRF analysis report are obtained because the analysis is performed after oxidation; however, in the actual sulfur denitrifying agent, the components do not exist as oxides but rather as iron sulfide, sulfur, etc.

[0053] Regarding the factors for denitrification performance and lifespan of the above-prepared example, it was confirmed that electron donors for sulfur denitrification microorganisms are sufficiently present due to the high sulfur content in the overall composition, and that iron components are also present in sufficient quantities to adsorb hydrogen sulfide (H2S) generated by sulfur components in the form of FeS or Fe2S3.

[0054] Those skilled in the art to which the present invention pertains will understand that the present invention may be implemented in other specific forms without altering its technical concept or essential features. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive, and the scope of the present invention is defined by the claims set forth below rather than by the detailed description, and all modifications or variations derived from the meaning and scope of the claims and equivalent concepts should be interpreted as being included within the scope of the present invention.

Claims

1. Based on the total weight, it comprises 50~70% by weight of mine drainage sludge, 15~30% by weight of waste iron sulfide generated from the hydrogen sulfide removal process, and 15~30% by weight of sulfur powder, and Sulfur powder uses sulfur generated in the desulfurization process, but, A sulfur denitrifying agent using sulfur-containing waste, characterized in that the sulfur generated in the desulfurization process is sulfur sludge generated in a desulfurization process using iron chelate (Fe-chelate) or sulfur-containing waste generated in a bio-sulfur treatment process.

2. In Claim 1, The mine drainage sludge is produced by a step of supplying mine drainage to a storage tank for storage while separating solid foreign substances contained in the mine drainage and allowing them to settle, and A step of removing moisture while drying the settled mine drainage sludge to achieve a moisture content of 60–80%, and A sulfur denitrifying agent using sulfur-containing waste, characterized by being manufactured by the step of filtering mine drainage sludge with improved moisture content through a sieve of a predetermined size and homogenizing it into mine drainage sludge having a size smaller than or equal to a standard size.

3. In Claim 1, The waste iron sulfide generated in the hydrogen sulfide removal process comprises a step of immersing the iron hydroxide-based waste desulfurizing agent, which has been broken down into hydrogen sulfide in a desulfurization tower, in water to remove excess hydrogen sulfide and foreign substances attached to the surface of the waste desulfurizing agent, while heating and stabilizing the waste iron sulfide; A step of drying stabilized waste iron sulfide to remove moisture, and A sulfur denitrifying agent using sulfur-containing waste, characterized by being manufactured by a step of homogenizing dried waste iron sulfide to have a size smaller than or equal to a standard size.

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