Hardness removal method and system for coal gasification wastewater

Abstract

The application provides a coal gasification wastewater hardness removal treatment method and system, which can be used for the pretreatment method of coal gasification wastewater with high suspended solids and high hardness. After the coal gasification wastewater is treated by the application, SS is less than 3 mg / L, total hardness is less than 10 mg / L, and the wastewater after treatment is basically free of hardness, which can effectively alleviate the scaling problem of the coal gasification device. In addition, the application provides a treatment method of anti-pollution filter material and a deep cleaning method of filter material. The anti-pollution filter material treated by chemical modification and plasma jet treatment is not scaled and polluted by itself, and the scaling formed by the suspended solids intercepted by the filter material can be removed by the combined use of stirring and a wringer, so that the filter material can always remain clean. The coal gasification wastewater hardness removal treatment method provided by the application has the characteristics of high treatment efficiency.

Description

Technical Field

[0001] This invention belongs to the field of applied chemical engineering, and in particular relates to a method and system for hardening treatment of coal gasification wastewater. Background Technology

[0002] Wastewater from coal gasification units using the Texaco process is characterized by high hardness, high COD, and high ammonia nitrogen. Since this wastewater is typically treated using biological processes such as SBR or A / O, the high hardness can cause scaling in transport pipelines, scaling and clogging of aeration discs in the biological treatment tanks, calcification of activated sludge, and blockage of reverse osmosis membranes for wastewater reuse. Therefore, hardness removal treatment of the coal gasification wastewater is necessary.

[0003] Currently, chemical hardening treatment can be used to remove hardness from coal gasification wastewater. This method involves adding alkaline substances such as sodium hydroxide and sodium carbonate to the wastewater, causing calcium and magnesium ions to precipitate and separate, thus achieving hardening removal. However, this method has drawbacks such as high reagent consumption and high sludge production.

[0004] To address the aforementioned shortcomings, some studies have employed resin adsorption processes to remove calcium and magnesium from coal gasification wastewater. Resin adsorption eliminates the need for introducing additional reagents into the wastewater, does not generate sludge, and produces relatively good water quality after treatment. However, due to the high suspended solids content in coal gasification wastewater, filter media is required to remove these solids before resin adsorption. Currently, the high hardness of the wastewater often leads to scaling on the filter media, resulting in decreased filtration performance and reduced efficiency in hardness removal.

[0005] Therefore, developing a high-efficiency method for hardening removal from coal gasification wastewater has become a research direction. Summary of the Invention

[0006] This invention provides a method for hardening treatment of coal gasification wastewater, which has the advantage of high treatment efficiency.

[0007] The present invention also provides a hardness removal treatment system for coal gasification wastewater, which has the characteristics of high treatment efficiency.

[0008] This invention provides a method for removing hardness from coal gasification wastewater, comprising the following steps: using anti-fouling filter media to sequentially filter the coal gasification wastewater and adsorb calcium and magnesium elements to obtain de-hardened water;

[0009] The antifouling filter media is prepared using a method comprising the following process:

[0010] The AFM glass filter media is brought into contact with an alkaline substance and subjected to alkaline etching treatment to obtain the alkaline etching product.

[0011] The alkaline etching product is contacted with an organic amine and then calcined to obtain an organic amine pore-expanding product.

[0012] The organic amine pore-expanding product is subjected to plasma jet treatment to obtain the antifouling filter material;

[0013] The calcium and magnesium adsorption treatment is performed using ion exchange resin.

[0014] The above-described method for treating coal gasification wastewater to remove hardness, wherein the calcination treatment temperature is 300-500℃ and the treatment time is 2-4 hours;

[0015] The plasma jet treatment has a processing voltage of 8-12kV and a processing time of 1-3h.

[0016] The method for removing hardness from coal gasification wastewater as described above further includes, before performing the calcium and magnesium element adsorption treatment, a first impurity removal adsorption treatment on the product obtained from the filtration treatment.

[0017] The method for removing hardness from coal gasification wastewater as described above further includes using a modified ion exchange resin to perform the calcium and magnesium adsorption treatment.

[0018] The modified ion exchange resin is prepared by a method comprising the following process:

[0019] The raw cation exchange resin was contacted with 1,2-dichloroethane to perform a first swelling treatment, thereby obtaining a first swollen product.

[0020] The first swollen product was contacted with an iron salt to obtain a first intermediate;

[0021] The first intermediate was contacted with 1,2-dichloroethane to undergo a second swelling treatment, resulting in a second swollen product.

[0022] The second swelling product is contacted with an amino acid porogen and hydroxyethyl sulfonic acid to obtain the modified ion exchange resin.

[0023] The first swelling treatment is carried out at a temperature of 70-90℃ for 5-15 hours.

[0024] The second swelling treatment is carried out at a temperature of 70-90℃ for 5-15 hours.

[0025] The iron salt is selected from at least one of ferric chloride and ferric sulfate;

[0026] The amino acid porogen is selected from at least one of glutamic acid, arginine, aspartic acid, and leucine.

[0027] In the above-described method for treating coal gasification wastewater to remove hardness, the raw material cation exchange resin is waste cation exchange resin from the desalination process.

[0028] The method for treating coal gasification wastewater as described above further includes regenerating the ion exchange resin after calcium and magnesium adsorption treatment using brine that has undergone ozone treatment and a second impurity removal adsorption treatment in sequence, to obtain regenerated wastewater.

[0029] The method for removing hardness from coal gasification wastewater as described above further includes ammonia removal treatment of the regenerated wastewater.

[0030] The present invention also provides a hardness removal treatment system for coal gasification wastewater, which is used to perform any of the above-mentioned hardness removal treatment methods for coal gasification wastewater, wherein the system includes a filter tank and a calcium and magnesium element adsorption tank that are interconnected.

[0031] The filter canister includes the anti-fouling filter media, and the calcium and magnesium element adsorption canister includes the ion exchange resin.

[0032] The coal gasification wastewater hardening treatment system described above further includes a filter media scrubber, the inlet of which is connected to the filter media outlet of the filter tank, and the outlet of which is connected to the filter media inlet of the filter tank.

[0033] The filter tank is provided with an anti-fouling filter material layer composed of the anti-fouling filter material, and the thickness of the anti-fouling filter material layer is 80-120cm.

[0034] The filter media outlet of the filter can is located below the filter media inlet of the filter can.

[0035] In the coal gasification wastewater hardening treatment system described above, the filter tank further includes an agitator, the agitator including agitator blades, the agitator blades being in contact with the anti-fouling filter media layer.

[0036] The coal gasification wastewater hardening treatment system described above further includes a first impurity removal adsorption tank, wherein the filter tank is connected to the calcium and magnesium element adsorption tank via the first impurity removal adsorption tank; and / or,

[0037] It also includes an ozone treatment tank and a second impurity removal adsorption tank that are interconnected, the outlet of the second impurity removal adsorption tank being connected to the reclaimed water inlet of the calcium and magnesium element adsorption tank; and / or,

[0038] It also includes a regenerated wastewater tank and an ammonia stripping tower. The inlet of the regenerated wastewater tank is connected to the regenerated wastewater outlet of the calcium and magnesium element adsorption tank, and the outlet of the regenerated wastewater tank is connected to the inlet of the ammonia stripping tower.

[0039] The coal gasification wastewater hardening treatment system described above further includes a filter tank, wherein the inlet of the filter tank is connected to the filter water outlet of the filter tank, the backwash water outlet of the filter tank is connected to the backwash water inlet of the filter tank, and the filter water outlet of the filter tank is connected to the filter water inlet of the calcium and magnesium element adsorption tank; and / or,

[0040] It also includes a water hardening tank, the inlet of which is connected to the water hardening outlet of the calcium and magnesium adsorption tank; and / or,

[0041] It also includes a backwash water collection tank, the inlet of which is connected to the backwash water outlet of the filter tank.

[0042] The present invention provides a method for hardening wastewater treatment from coal gasification. First, the wastewater is filtered using a non-fouling, scale-resistant filter media. Then, calcium and magnesium ion adsorption resin is used to remove calcium and magnesium ions from the wastewater, resulting in de-hardened water. The non-fouling filter media makes the filtration device less structurally complex and allows for long-term continuous operation. Therefore, the hardening treatment method for coal gasification wastewater provided by this invention is highly efficient. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced one by one below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 A schematic diagram of the first coal gasification wastewater hardening treatment system provided by the present invention;

[0045] Figure 2 A schematic diagram of the second coal gasification wastewater hardening treatment system provided by the present invention;

[0046] Figure 3 This is a schematic diagram of the third coal gasification wastewater hardening treatment system provided by the present invention.

[0047] Explanation of reference numerals in the attached figures:

[0048] 101 - Filter canister;

[0049] 102-Calcium and Magnesium Element Adsorption Tank;

[0050] 103 - Filter media scrubber;

[0051] 104 - Agitator;

[0052] 105 - First impurity removal adsorption tank;

[0053] 106 - Ozone Treatment Tank;

[0054] 107 - Second impurity removal adsorption tank;

[0055] 108 - Reclaimed wastewater tank;

[0056] 109 - Ammonia stripping tower;

[0057] 110 - Filter water tank;

[0058] 111 - Except for hard water tanks;

[0059] 112 - Backwash water collection tank. Detailed Implementation

[0060] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below. The specific embodiments listed below are merely descriptions of the principles and features of the present invention, and the examples are only for explaining the present invention and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0061] Currently, due to the high suspended solids content in coal gasification wastewater, filter media is needed to remove these solids before resin adsorption. However, the high hardness of coal gasification wastewater often leads to scaling on the filter media, reducing the hardness removal efficiency. The inventors analyzed that this is because the filter media used in existing technologies are prone to attracting dirt due to their surface properties, resulting in a large accumulation of dirt and subsequent scaling and caking. Therefore, if the surface of the filter media can be modified, scaling and caking can be prevented, thereby improving the hardness removal efficiency of coal gasification wastewater.

[0062] Based on this, the first aspect of the present invention provides a method for removing hardness from coal gasification wastewater, the method comprising the following steps: using anti-fouling filter media to sequentially filter the coal gasification wastewater and adsorb calcium and magnesium elements to obtain de-hardened water;

[0063] Antifouling filter media are prepared using a method that includes the following processes:

[0064] The AFM glass filter media is brought into contact with an alkaline substance and subjected to alkaline etching treatment to obtain the alkaline etching product.

[0065] The alkaline etching product is contacted with an organic amine and then calcined to obtain an organic amine pore-expanding product.

[0066] The pore-expanding products of organic amines were subjected to plasma jet treatment to obtain antifouling filter media;

[0067] The calcium and magnesium adsorption treatment was performed using ion exchange resin.

[0068] The present invention provides a method for removing hardness from coal gasification wastewater, specifically the calcium and magnesium ions present in the wastewater. The method first filters the wastewater to remove suspended solids, then uses an ion exchange resin to remove calcium and magnesium ions, thus completing the treatment and obtaining de-hardened water.

[0069] This invention does not limit the specific type of ion exchange resin, as long as it meets the requirement of adsorbing calcium and magnesium ions. For example, in one embodiment, the resin can be selected from at least one of the 001*7 type, HYA-10 type, and LSC-100 type cation exchange resins. Furthermore, this invention does not limit the source of the ion exchange resin; it can be virgin resin, regenerated resin, or a modified product obtained from waste cation exchange resin, as long as it meets the requirement of adsorbing calcium and magnesium ions.

[0070] Furthermore, in the above process, the antifouling filter media is obtained by modifying AFM glass filter media. Specifically, alkaline etching cleans impurities from the filter media surface and partially dissolves the silicon elements on the surface, preparing it for subsequent processing. Alkaline etching involves contacting the AFM glass filter media with an alkaline substance, which includes at least one of sodium hydroxide and potassium hydroxide. It is understood that to improve the efficiency of alkaline etching, the alkaline substance may also include water, i.e., dissolving at least one of sodium hydroxide and potassium hydroxide in water to form an aqueous solution for alkaline etching.

[0071] The present invention does not limit the processing conditions of alkaline etching. In one embodiment, the AFM glass filter material can be crushed to 0.25 mm to 0.5 mm and then mixed with a sodium hydroxide aqueous solution with a mass fraction of 2%. The resulting mixture is stirred at 80°C for 4 hours, then washed with deionized water 6 to 8 times and dried at 120°C to obtain the alkaline etching product.

[0072] The process of calcining the alkaline etching product after contact with an organic amine utilizes the reactivity between the organic amine and AFM glass filter media to increase the specific surface area of ​​the glass filter media, improve filtration accuracy, and reduce SS in the effluent. The organic amine is selected from at least one of ethanolamine and tetraethylammonium hydroxide. This invention does not limit the specific processing conditions of the above process. In one embodiment, the alkaline etching product, ethanolamine, and tetraethylammonium hydroxide are added to water in a mass ratio of 10:1:0.05 and stirred at 60°C for 12 hours. Then, the mixture is washed 3-5 times with deionized water, followed by calcination at 400°C for 3 hours in an air atmosphere to obtain the organic amine pore-expanding product.

[0073] Plasma jet treatment of organic amine pore-expanding products specifically refers to contacting the organic amine pore-expanding products with a plasma jet. This treatment can increase the ZETA potential of the resulting filter material surface, thereby improving its antifouling ability. This invention does not limit the specific conditions of the plasma jet treatment. In one embodiment, an array-type plasma jet device customized by the Institute of Metal Research, Chinese Academy of Sciences, can be used to perform plasma jet treatment on the organic amine pore-expanding products.

[0074] The hardness removal method for coal gasification wastewater provided by this invention uses a fouling-resistant filter media with a large specific surface area and a high Zeta potential to filter the wastewater, followed by the removal of calcium and magnesium ions using ion exchange resin. Because the fouling-resistant filter media is not prone to clogging and caking, it allows for a longer continuous filtration time, thus the hardness removal method for coal gasification wastewater provided by this invention is highly efficient.

[0075] In one embodiment, to enhance the antifouling properties of the filter material, the calcination treatment temperature can be controlled at 300–500°C, and the treatment time at 2–4 hours. Furthermore, the plasma jet treatment voltage can be controlled at 8–12 kV, the treatment frequency at 8.8 kHz, and the treatment time at 1–3 hours. Suitable treatment conditions can give the antifouling filter material a higher ZETA potential, resulting in more negatively charged surface groups and thus stronger antifouling properties.

[0076] Furthermore, in one specific embodiment, before the calcium and magnesium adsorption treatment, a first impurity removal adsorption treatment is performed on the product obtained from the filtration process. The inventors discovered that directly subjecting the filtered product to calcium and magnesium adsorption often leads to a shortened lifespan of the ion exchange resin. Through research, the inventors found that this is because coal gasification wastewater often contains iron, which cannot be removed during filtration. When iron comes into contact with the ion exchange resin used for calcium and magnesium adsorption, it occupies or blocks the active sites of the ion exchange resin, resulting in a shortened lifespan. Therefore, performing a first impurity removal adsorption treatment on the filtered product before calcium and magnesium adsorption removes iron, thereby extending the lifespan of the ion exchange resin used for calcium and magnesium adsorption. Consequently, the coal gasification wastewater hardening treatment method provided by this invention has higher efficiency and lower cost.

[0077] In one embodiment, the first metal element removal process is performed using a strong acidic ion exchange resin, such as D001 type resin, which can adsorb iron elements in water when in contact with water containing iron.

[0078] Furthermore, in order to reduce the cost of the coal gasification wastewater removal method provided by the present invention, one embodiment further includes using a modified ion exchange resin to perform calcium and magnesium adsorption treatment.

[0079] The modified ion exchange resin is prepared by a method comprising the following steps:

[0080] The raw cation exchange resin was contacted with 1,2-dichloroethane to perform a first swelling treatment, thereby obtaining a first swollen product.

[0081] The first swollen product was contacted with an iron salt to obtain the first intermediate;

[0082] The first intermediate was contacted with 1,2-dichloroethane to undergo a second swelling treatment, yielding a second swollen product.

[0083] The second swelling product was contacted with an amino acid porogen and hydroxyethyl sulfonic acid to obtain a modified ion exchange resin.

[0084] The first swelling treatment is carried out at a temperature of 70-90℃ for 5-15 hours.

[0085] The second swelling treatment is carried out at a temperature of 70-90℃ for 5-15 hours.

[0086] The iron salt is selected from at least one of ferric chloride and ferric sulfate;

[0087] The amino acid porogen is selected from at least one of glutamic acid, arginine, aspartic acid, and leucine.

[0088] The raw cation exchange resin was contacted with 1,2-dichloroethane to perform a first swelling treatment, thereby obtaining a first swollen product.

[0089] The first swollen product was contacted with an iron salt to obtain the first intermediate;

[0090] The first intermediate was contacted with 1,2-dichloroethane to undergo a second swelling treatment, yielding a second swollen product.

[0091] The second swelling product was contacted with an amino acid porogen and hydroxyethyl sulfonic acid to obtain a modified ion exchange resin.

[0092] The first swelling treatment is carried out at a temperature of 70-90℃ for 5-15 hours.

[0093] The second swelling treatment is carried out at a temperature of 70-90℃ for 5-15 hours.

[0094] The iron salt is selected from at least one of ferric chloride and ferric sulfate;

[0095] The amino acid porogen is selected from at least one of glutamic acid, arginine, aspartic acid, and leucine.

[0096] First, 1,2-dichloroethane is a crosslinking agent that can increase the degree of crosslinking of the resin and improve its stability. Therefore, using 1,2-dichloroethane for a first swelling treatment at a temperature of 70-90℃ for 5-15 hours, and a second swelling treatment at the same temperature for 5-15 hours, can further improve the stability of the raw material cation exchange resin.

[0097] Secondly, when the raw cation exchange resin is contacted with an iron salt selected from at least one of ferric chloride and ferric sulfate, the iron salt acts as a crosslinking agent, allowing the raw cation exchange resin to crosslink again, thereby providing a greater adsorption capacity for calcium and magnesium elements. After the raw cation exchange resin is contacted with the iron salt, when it is contacted with an amino acid porogen and hydroxyethyl sulfonic acid, the amino acid porogen and hydroxyethyl sulfonic acid can perform secondary pore formation and re-sulfonation on the resin, increasing the surface area and the number of sulfonic acid groups of the raw ion exchange resin, thereby further improving the resin surface area and adsorption capacity, resulting in a modified ion exchange resin. The raw cation exchange resin can be selected from at least one of the 001*7 type, HYA-10 type, and LSC-100 type cation exchange resins.

[0098] More specifically, the contact between the raw material cation exchange resin and iron salt, amino acid porogen, and hydroxyethyl sulfonic acid can all be carried out in 1,2-dichloroethane.

[0099] In one embodiment, the raw material cation exchange resin is first contacted with 1,2-dichloroethane for a first swelling treatment. Then, 0.5-1.5% by mass of iron salt is added to the 1,2-dichloroethane that has undergone the first swelling treatment, and the temperature is raised to 80°C to allow the iron salt to react with the raw material cation exchange resin for 8-12 hours. The cation exchange resin obtained after reacting with iron salts was extracted with ethanol for 10-14 hours, and then contacted again with 1,2-dichloroethane for a second swelling treatment. Subsequently, 0.005-0.02% (by weight of 1,2-dichloroethane) of amino acid porogen was added to the 1,2-dichloroethane that had undergone the second swelling treatment, and the reaction was carried out at 40-60°C for 4 hours. Then, 0.5-1.5% (by weight of 1,2-dichloroethane) of hydroxyethyl sulfonic acid was added to the reaction system, and the temperature was raised to 80°C for 8-12 hours. Finally, the mixture was washed 10 times with 5% sodium chloride solution to make the washing solution neutral, and then extracted with ethanol for 4 hours to obtain the modified ion exchange resin.

[0100] It is understood that, in order to further improve the performance of the modified ion exchange resin, in one embodiment, before the raw material cation exchange resin is brought into contact with 1,2-dichloroethane, the raw material cation exchange resin is subjected to acid washing treatment with hydrochloric acid solution and alkali washing treatment with sodium hydroxide aqueous solution, respectively, to remove contaminants such as organic matter, microorganisms, and inorganic salts from the surface of the raw material cation exchange resin.

[0101] In one embodiment, the raw material cation exchange resin refers to an ion exchange resin with calcium and magnesium adsorption function that has been replaced and phased out during the production process. Using the above method, the waste cation exchange resin can regain some of its calcium and magnesium adsorption function, allowing it to continue to be used for calcium and magnesium adsorption treatment, thereby reducing the cost of the coal gasification wastewater hardening treatment method provided by this invention. More specifically, the raw material cation exchange resin is a waste cation exchange resin from the desalination process.

[0102] In one embodiment, the method for treating coal gasification wastewater provided by the present invention further includes regenerating the ion exchange resin after calcium and magnesium adsorption treatment by using brine that has undergone ozone treatment and a second impurity removal adsorption treatment in sequence, to obtain regenerated water.

[0103] After calcium and magnesium adsorption treatment, the ion exchange resin needs to be regenerated to restore its adsorption capacity. To further reduce the hardness in the coal gasification wastewater treatment method provided by this invention, brine can be used as a raw material to regenerate the ion exchange resin. Brine is typically wastewater containing 8-20% sodium chloride by mass, with a TOC <15 mg / L, and may also contain organic matter and metal elements such as Fe, Mn, and Ti. Therefore, before using brine for regeneration, it needs to be contacted with ozone to degrade the organic matter, followed by a second impurity removal adsorption treatment. The second impurity removal adsorption treatment involves using a strongly acidic ion exchange resin to adsorb the Fe, Mn, Ti, and other metal elements contained therein. The resulting treated water is used to regenerate the ion exchange resin that performed the calcium and magnesium adsorption treatment, resulting in regenerated wastewater. During the regeneration process, sodium ions in the treated water displace the Ca and Mg ions adsorbed on the adsorption groups of the ion exchange resin, thus completing the regeneration of the ion exchange resin.

[0104] Specifically, in ozone treatment, the ozone dosage can be controlled at 2–5 kg / m³. 3 The treatment time was 1 hour, and the TOC in the desalinated water after ozone treatment was <8 mg / L.

[0105] The second impurity removal adsorption treatment for brine can use the same type of resin as the first impurity removal adsorption treatment.

[0106] This invention does not limit the specific regeneration process of the ion exchange resin, and commonly used regeneration processes in the art can be used. In one embodiment, the above regeneration process includes the following three steps performed sequentially:

[0107] 1) Clean the ion exchange resin in the calcium and magnesium adsorption tank with demineralized water at a rate of 2 bv / h for 2 hours;

[0108] 2) The ion exchange resin in the calcium and magnesium adsorption tank was cleaned for 2 hours with a mixture of demineralized water and brine at a rate of 1 bv / h. The dilution ratio of demineralized water to brine was 1:1 to 2.

[0109] 3) Clean the ion exchange resin in the calcium and magnesium adsorption tank with desalinated water at a rate of 2 bv / h for 2 hours.

[0110] In step 1), the desalinated water is not treated with ozone, but directly undergoes the second metal ion adsorption treatment to remove metal elements such as Fe, Mn, and Ti. After that, it comes into contact with the ion exchange resin in the calcium and magnesium element adsorption tank to replace the residual coal gasification wastewater in the ion exchange resin, thereby reducing the concentration of organic matter and ammonia nitrogen in the regenerated wastewater. The resulting wastewater is then discharged into a sewage treatment plant for treatment.

[0111] In step 2), the desalinated water is mixed with the ozone-treated brine and then subjected to a second metal ion adsorption treatment to remove metal elements such as Fe, Mn, and Ti. Afterward, it contacts the ion exchange resin in the calcium and magnesium adsorption tank. During this process, the brine regenerates the ion exchange resin, replacing residual organic matter, ammonia nitrogen, and calcium and magnesium elements adsorbed by the resin. The desalinated water is used to dilute and adjust the brine concentration, reducing the amount of brine used. The resulting regenerated wastewater undergoes ammonia removal treatment.

[0112] In step 3), the demineralized water undergoes no ozone treatment and is directly subjected to the second metal ion adsorption treatment to remove metal elements such as Fe, Mn, and Ti. Afterward, it contacts the ion exchange resin in the calcium and magnesium element adsorption tank. The purpose of introducing demineralized water after brine is to wash away the salt in the ion exchange resin and prevent salt from entering the hard water. The ion exchange resin is regenerated, and the resulting regenerated wastewater is then sent to the 109-ammonia stripping tower for ammonia removal.

[0113] In a more specific embodiment, the method for treating coal gasification wastewater provided by the present invention further includes ammonia removal treatment of the regenerated wastewater. The regenerated wastewater contains calcium and magnesium ions from the ion exchange resin and ammonium salts from the coal gasification wastewater. Ammonia removal treatment of the regenerated wastewater can remove the ammonium salts, thereby meeting emission standards. In one embodiment, the ammonia removal treatment includes adjusting the pH value of the regenerated wastewater to greater than 11 before it enters an ammonia stripping tower for ammonia removal. The ammonia stripping tower uses cross-flow trays with at least 30 trays. A pH value greater than 11 helps the nitrogen in the resin regeneration liquid to be converted into ammonia and then removed. Using cross-flow trays and having at least 30 trays in the ammonia stripping tower achieves better ammonia removal results.

[0114] A second aspect of the present invention provides a hardness removal treatment system for coal gasification wastewater, the system comprising a filter tank and a calcium and magnesium element adsorption tank connected to each other; the filter tank includes anti-fouling filter media, and the calcium and magnesium element adsorption tank includes ion exchange resin.

[0115] Figure 1 A schematic diagram of a first type of coal gasification wastewater hardening treatment system used in the coal gasification wastewater treatment method provided by the present invention is shown below. Figure 1 As shown, the device includes a 101-filter tank and a 102-calcium-magnesium element adsorption tank that are interconnected. Specifically, the filtered water outlet of the 101-filter tank is connected to the filtered water inlet of the 102-calcium-magnesium element adsorption tank. The 101-filter tank contains anti-fouling glass filter media with a certain thickness, forming an anti-fouling filter media layer. The 102-calcium-magnesium element adsorption tank contains ion exchange resin for calcium and magnesium element adsorption treatment, resulting in de-hardened water.

[0116] It is understood that, in one embodiment, the 101-filter tank, in addition to the anti-fouling filter media layer, also includes a support layer disposed at the bottom of the anti-fouling filter media layer. The present invention does not limit the specific structure of the support layer; commonly used filter media in the art can be used, such as glass sand with different particle sizes. More specifically, in one embodiment, the filter media in the 101-filter tank, from top to bottom, are: an anti-fouling filter media layer with a particle size of 0.25–0.5 mm and a thickness of 80–120 cm; glass sand with a particle size of 0.25–0.5 mm and a thickness of 80 cm; glass sand with a particle size of 0.4–0.8 mm and a thickness of 25 mm; and glass sand with a particle size of 1–2 mm and a thickness of 25 mm.

[0117] During the operation of the above system, the coal gasification wastewater enters the 101-filter tank and is filtered. Then, it enters the 102-calcium-magnesium adsorption tank through the filtered water outlet of the 101-filter tank and the filtered water inlet of the 102-calcium-magnesium element adsorption tank in sequence for calcium and magnesium element adsorption treatment, thus obtaining de-hardened water.

[0118] The coal gasification wastewater treatment device provided by this invention uses a 101-filter tank containing anti-fouling glass filter media to filter the coal gasification wastewater, and then uses a 102-calcium and magnesium element adsorption tank containing ion exchange resin to remove calcium and magnesium elements. The 101-filter tank is prone to scaling and has a long continuous operating time, thus the device has the characteristic of high treatment efficiency.

[0119] Figure 2 A schematic diagram of a second coal gasification wastewater hardening treatment system used in the coal gasification wastewater treatment method provided by the present invention is shown below. Figure 2 As shown, the device also includes a 103-filter media scrubber, the inlet of which is connected to the filter media outlet of the 101-filter tank, and the outlet of which is connected to the filter media inlet of the 101-filter tank.

[0120] The thickness of the anti-fouling filter layer is 80-120cm;

[0121] The filter media outlet of the filter canister is located below the filter media inlet of the filter canister;

[0122] The filter media outlet of the 101-filter tank is located at 80-110% of the laminar fluidization height of the antifouling filter media;

[0123] The filter media inlet of the 101-filter tank is located 10-30cm below the top of the anti-fouling filter media layer.

[0124] The fluidization height refers to the thickness of the antifouling filter media layer when it is in a fluidized state during backwashing. The filter media outlet of the 101-filter tank being located at 80-110% of the fluidization height of the top layer of the 101-filter tank means that the outlet is located between 20% of the fluidization height below the top of the fluidized antifouling filter media layer and 10% of the fluidization height above the top of the fluidized antifouling filter media layer. The filter media inlet of the 101-filter tank is located 10-30 cm below the top of the antifouling filter media layer, and its elevation is lower than the filter media outlet of the 101-filter tank.

[0125] The 103-filter media scrubber is used to scrub the filter media in the 101-filter tank. Through high-speed friction scrubbing, it disperses and breaks up the small amount of blocky agglomerates that have accumulated in the filter media during long-term operation, thus maintaining the cleanliness of the filter media layer. Specifically, firstly, the filtered water (i.e., the product obtained by filtering coal gasification wastewater) enters the 101-filter tank through the backwash water inlet, causing the anti-fouling filter media layer to become fluidized. The filter media is fluidized to 100% of its expansion height. The fluidized anti-fouling filter media then enters the 103-filter media scrubber through the filter media outlet of the 101-filter tank. The 103-filter media scrubber operates at a speed of 100-300 rpm. Under the rotational friction of the 103-filter media scrubber, the dirt attached to the anti-fouling filter media is detached. The detached dirt, along with the filtered water and the treated anti-fouling filter media, returns through the filter media inlet of the 101-filter tank, completing the scrubbing process. The filtered water containing dirt leaves the 101-filter tank for further treatment.

[0126] This invention does not limit the specific structure of the 103-filter media scrubber, and commonly used 103-filter media scrubbers in the art can be used. In one embodiment, the 103-filter media scrubber uses a cylindrical brush rod inside, the diameter of which is 200-400mm, and the brush rod material is one of nylon filament, stainless steel wire, or sisal.

[0127] Furthermore, the present invention is not limited to the method of introducing filter media into the 103-filter media scrubber; in one embodiment, a centrifugal pump can be used to drive ( Figure 1 (Not shown in the diagram). This invention does not limit the specific location of the centrifugal pump. It can be installed on any pipeline between 103-filter media scrubber and 101-filter tank. That is, it can be installed between the filter media outlet of 101-filter tank and the inlet of 103-filter media scrubber, or it can be installed between the outlet of 103-filter media scrubber and the filter media inlet of 101-filter tank.

[0128] To go further, such as Figure 2 As shown, the 101-filter tank further includes a 104-agitator, which comprises agitator blades that contact the antifouling filter media layer. More specifically, in one embodiment, the lowest point of the agitator blades is located 150 mm below the top of the antifouling filter media layer. The agitator blades extending to a suitable depth into the antifouling filter media layer facilitates effective agitation of the antifouling media, further improving efficiency while preventing scaling and solidification. It is understood that the 104-agitator can be driven by an electric motor.

[0129] 104-The agitator can be any of the rake agitator or a flat-blade disc turbine. 101-When the filtration pressure drop of the filter tank reaches 0.05-0.1MPa, turn on the 104-agitator to break up and disperse the caking material formed on the top of the anti-fouling filter layer. The agitator speed is 50-120rpm and the agitation and breaking time is 5-10min.

[0130] Figure 3 A schematic diagram of a third type of coal gasification wastewater hardening treatment system used in the coal gasification wastewater treatment method provided by the present invention is shown below. Figure 3 As shown, the first type of coal gasification wastewater treatment device provided by the present invention further includes 105-first impurity removal adsorption tank, and 101-filter tank is connected to 102-calcium and magnesium element adsorption tank through 105-first impurity removal adsorption tank. 105-first impurity removal adsorption tank is equipped with a strongly acidic ion exchange resin for adsorbing iron elements, used to adsorb metal elements from the product obtained by filtration. Specifically, the product obtained by filtration enters 105-first impurity removal adsorption tank for adsorption of metal elements, and the adsorbed product enters 102-calcium and magnesium element adsorption tank for adsorption of calcium and magnesium elements. Controlling the wastewater flow rate in 105-first impurity removal adsorption tank to 20-30 m / h can achieve better adsorption effect.

[0131] Furthermore, it also includes an interconnected 106-ozone treatment tank and 107-second impurity removal adsorption tank. The outlet of the 107-second impurity removal adsorption tank is connected to the reclaimed water inlet of the 102-calcium-magnesium element adsorption tank. The 106-ozone treatment tank is used for ozone treatment of brine. The 107-second impurity removal adsorption tank is equipped with the same type of resin as the 105-first impurity removal adsorption tank, used for adsorbing metal elements from brine that has undergone ozone treatment or has not, removing metal elements such as Fe, Mn, and Ti. Specifically, when the brine undergoes ozone treatment and metal element adsorption treatment sequentially, it first undergoes ozone treatment in the 106-ozone treatment tank, then enters the 107-second impurity removal adsorption tank for metal element adsorption treatment, and then enters the 102-calcium-magnesium element adsorption tank through the reclaimed water inlet to regenerate the cation exchange resin therein, removing impurities adsorbed by the cation exchange resin, resulting in reclaimed wastewater.

[0132] In one embodiment, the above-mentioned regeneration process includes the following three steps performed sequentially:

[0133] 1) Clean the ion exchange resin in the 102-calcium-magnesium element adsorption tank for 2 hours using demineralized water (from the plant's demineralized water preparation unit) at a rate of 2 bv / h;

[0134] 2) The ion exchange resin in the 102-calcium magnesium element adsorption tank was cleaned for 2 hours with a mixture of demineralized water and brine at a rate of 1 bv / h. The dilution ratio of demineralized water to brine was 1:1 to 2.

[0135] 3) Clean the ion exchange resin in the 102-calcium-magnesium element adsorption tank with desalinated water at a rate of 2 bv / h for 2 hours.

[0136] In step 1), the desalinated water is directly subjected to metal ion adsorption treatment without ozone treatment. After removing metal elements such as Fe, Mn, and Ti, it enters the 102-calcium-magnesium element adsorption tank through the regeneration water inlet. It comes into contact with the ion exchange resin in the 102-calcium-magnesium element adsorption tank, replacing the residual coal gasification wastewater in the ion exchange resin, reducing the concentration of organic matter and ammonia nitrogen in the regeneration wastewater, and the resulting wastewater is discharged into the sewage treatment plant for treatment.

[0137] In step 2), the desalinated water is mixed with the ozone-treated brine and then subjected to metal ion adsorption treatment to remove metal elements such as Fe, Mn, and Ti. The desalinated water then enters the 102-calcium-magnesium element adsorption tank through the regeneration inlet, contacting the ion exchange resin in the tank. During this process, the brine regenerates the ion exchange resin, replacing residual organic matter, ammonia nitrogen, and calcium and magnesium elements adsorbed by the resin. The desalinated water is used to dilute and adjust the brine concentration, reducing the amount of brine used. The resulting regenerated wastewater enters the 109-ammonia removal tower for ammonia removal treatment.

[0138] In step 3), the desalinated water undergoes direct metal ion adsorption treatment without ozone treatment. After removing metal elements such as Fe, Mn, and Ti, it enters the 102-calcium-magnesium element adsorption tank through the regeneration water inlet, contacting the ion exchange resin in the tank. The purpose of introducing desalinated water after the brine is to wash away salt from the ion exchange resin and prevent salt from entering the hard water. The resulting regenerated wastewater then enters the 109-ammonia stripping tower for ammonia removal treatment.

[0139] It is worth noting that in the above process, the demineralized water enters through the pipeline between the 106-ozone treatment tank and the 107-second impurity removal adsorption tank and flows to the 107-second impurity removal adsorption tank.

[0140] Furthermore, the wastewater treatment system for coal gasification includes a 108-regeneration wastewater tank and a 109-ammonia stripping tower. The inlet of the 108-regeneration wastewater tank is connected to the outlet of the 102-calcium-magnesium element adsorption tank, and the outlet of the 108-regeneration wastewater tank is connected to the inlet of the 109-ammonia stripping tower. The 108-regeneration wastewater tank receives the regeneration wastewater generated during the regeneration process in the 102-calcium-magnesium element adsorption tank. After temporary storage in the 108-regeneration wastewater tank, the regeneration wastewater enters the 109-ammonia stripping tower. The 109-ammonia stripping tower removes ammonium salts from the regeneration wastewater to meet emission standards. In one embodiment, the 109-ammonia stripping tower uses cross-flow trays with at least 30 trays. The 109-ammonia stripping tower with these characteristics achieves better ammonia removal efficiency.

[0141] Depend on Figure 3 As can be seen, the hardness removal treatment system for coal gasification wastewater provided by the present invention further includes a 110-filter water tank. The inlet of the 110-filter water tank is connected to the filtered water outlet of the 101-filter tank, the backwash water outlet of the 110-filter water tank is connected to the backwash water inlet of the 101-filter tank, and the filtered water outlet of the 110-filter water tank is connected to the filtered water inlet of the 102-calcium-magnesium element adsorption tank. The 110-filter water tank is used to contain the filtration product obtained from the filtration treatment of the coal gasification wastewater. This filtration product can enter the 102-calcium-magnesium element adsorption tank from the filtered water outlet of the 110-filter water tank through the filtered water inlet of the 102-calcium-magnesium element adsorption tank for calcium and magnesium element adsorption treatment. On the other hand, it can enter the 101-filter tank from the backwash water outlet of the 110-filter water tank through the backwash water inlet of the 101-filter tank to backwash the filter media, including the anti-fouling filter media, inside the 101-filter tank.

[0142] Furthermore, the coal gasification wastewater hardening treatment system provided by this invention also includes a 111-hardening water tank, the inlet of which is connected to the hardening water outlet of the 102-calcium and magnesium element adsorption tank. The 111-hardening water tank is used to temporarily hold the hardened water for subsequent process treatment.

[0143] Furthermore, the system also includes a 112-backwash water collection tank, the inlet of which is connected to the backwash water outlet of the 101-filter tank. The 112-backwash water collection tank is used to collect the wastewater generated from backwashing the 101-filter tank for subsequent process treatment.

[0144] The following specific embodiments further illustrate the method for treating coal gasification wastewater provided by the present invention.

[0145] Sources of raw materials and equipment:

[0146] AFM glass filter media, using 0# filter media, is sourced from Yixing Xinzhan Environmental Protection Company.

[0147] Ethanolamine, tetraethylammonium hydroxide, hydroxyethylsulfonic acid, glutamic acid, arginine, aspartic acid, and leucine are from Sinopharm Group Co., Ltd.

[0148] 1,2-Dichloroethane, sodium chloride, sodium hydroxide, and hydrochloric acid were obtained from Wanhua Chemical's PVC and chlor-alkali plants.

[0149] The waste ion exchange resin was taken from the desalination plant of Wanhua Chemical Environmental Protection Technology.

[0150] The equipment in the coal gasification wastewater hardening treatment system comes from the gasification unit of Wanhua Chemical's Fujian Industrial Park.

[0151] Example 1

[0152] The wastewater used in this embodiment was taken from the outlet wastewater of the black water settling tank of the coal gasification unit of Wanhua Chemical (Fujian) Co., Ltd., with a wastewater treatment capacity of 80m³. 3 / h, the wastewater contains 450mg / L calcium ions, 24mg / L magnesium ions, and 600mg / L COD.

[0153] This embodiment uses Figure 3 The hardness removal treatment system shown treats the coal gasification wastewater. For example... Figure 3 As shown, the system includes 101-filter tank, 102-calcium and magnesium element adsorption tank, 103-filter media scrubber, 104-stirring paddle, 105-first impurity removal adsorption tank, 106-ozone treatment tank, 107-second impurity removal adsorption tank, 108-regenerated wastewater tank, 109-ammonia stripping tower, 110-filtered water tank, 111-hard water removal tank, and 112-backwash water collection tank.

[0154] Among them, the filtered water outlet of 101-filter tank is connected in sequence to the filtered water inlet of 110-filter water tank, 105-first impurity removal adsorption tank and 102-calcium and magnesium element adsorption tank. The hard water outlet of 102-calcium and magnesium element adsorption tank is connected to the hard water outlet. The regenerated wastewater outlet of 102-calcium and magnesium element adsorption tank is connected to the inlet of 108-regenerated wastewater tank. The outlet of 108-regenerated wastewater tank is connected to the inlet of 109-ammonia stripping tower. The bottom outlet of 109-ammonia stripping tower is connected to the sea discharge pipeline.

[0155] In addition, the 106-ozone treatment tank is connected to the reclaimed water inlet of the 102-calcium and magnesium element adsorption tank via the 107-second impurity removal adsorption tank.

[0156] In addition, the backwash water outlet of the 110-filter water tank is connected to the backwash water inlet of the 101-filter tank, and the backwash water outlet of the 101-filter tank is connected to the inlet of the 112-backwash water collection tank.

[0157] In addition, 104 is the stirring paddle inside the 110-filter water tank, the filter media outlet of the 110-filter water tank is connected to the filter media inlet of the 103-filter media scrubber, the filter media inlet of the 110-filter water tank is connected to the filter media inlet of the 103-filter media scrubber, the filter media outlet of the 101-filter tank is located at 80% of the fluidization height of the antifouling filter media layer, and the filter media inlet of the 101-filter tank is located 20cm below the top of the antifouling filter media layer.

[0158] 101-Filter tank filled with 10m 3 The anti-fouling filter media has a particle size of 0.25mm to 0.5mm, a filtration accuracy of 1μm, a media filling height of 800mm, and a filtration speed of 8m / h. The stirring paddle extends 150mm into the anti-fouling filter media layer. At this point, the filter media in the filter tank (101) from top to bottom are: an anti-fouling filter media layer with a particle size of 0.25 to 0.5mm and a thickness of 80cm; glass sand with a particle size of 0.25 to 0.5mm and a thickness of 80cm; glass sand with a particle size of 0.4 to 0.8mm and a thickness of 25mm; and glass sand with a particle size of 1-2mm and a thickness of 25mm.

[0159] The antifouling filter material is prepared using the following method:

[0160] AFM glass filter media was crushed to 0.25mm-0.5mm and etched with 2% NaOH at 80℃ for 4 hours with stirring. After the reaction, it was washed with deionized water 6-8 times and dried at 120℃. Then, the dried filter media, ethanolamine, and tetraethylammonium hydroxide were added to water at a mass ratio of 10:1:0.05 and stirred at 60℃ for 12 hours to perform organic amine pore-expansion treatment. After washing with deionized water 3-5 times, it was calcined at 400℃ in air atmosphere for 3 hours and then cooled to room temperature. Finally, it was subjected to atmospheric pressure jet plasma treatment with a discharge voltage of 8-12kV, a frequency of 8.8kHz, and a treatment time of 3 hours to obtain antifouling filter media.

[0161] The operating parameters of the 101-filter tank are controlled as follows: operating pressure 0.2MPa, filtration time 7h, backwash time 30min, backwashing process consists of 5min stirring, 5min sedimentation, 10min water backwashing, 2min forward washing, and 8min scrubbing, with a stirring speed of 50rpm. The filter media is conveyed to the 103-filter media scrubber, and the outlet of the 103-filter media scrubber is connected to the filter media inlet 20cm below the top of the anti-fouling filter media layer. The 103-filter media scrubber uses cylindrical brush rollers with a diameter of 400mm, and the brush roller material is nylon filament.

[0162] 105-First impurity removal adsorption tank and 107-Second impurity removal adsorption tank are each filled with 1m³ of [unclear text - possibly a typo, should be "1m"]. 3The D001 strong acid ion exchange resin adsorbs metal elements in wastewater, with a wastewater flow rate of 20 m / h inside the tank.

[0163] 102-Calcium and magnesium element adsorption tank is filled with 20m 3 The modified ion exchange resin adsorbs calcium and magnesium ions in the wastewater. Each adsorption cycle lasts 18 hours. After treatment, part of the wastewater is discharged into the biological system and the rest is returned to the gasification system.

[0164] The modified ion exchange resin was prepared using the following method:

[0165] Waste HYA-10 cation exchange resin discarded from demineralized water purification cation exchange beds was soaked in 5% hydrochloric acid for 24 hours, followed by washing with 5% NaOH 3-5 times, and then washing with deionized water until the pH reached 6-9 to remove impurities from the waste resin. The resulting cation exchange resin was then soaked in 1,2-dichloroethane for 6 hours for the first swelling treatment. At 50°C, 1% (by weight) ferric chloride of 1,2-dichloroethane was added to the 1,2-dichloroethane and stirred for 1 hour. The temperature was then raised to 80°C and reacted for 10 hours. After the reaction, the resin was washed with deionized water until the washing liquid was clear, followed by extraction with ethanol for 12 hours to obtain... The post-crosslinked ion exchange resin was then soaked in 1,2-dichloroethane for 2 hours for a second swelling treatment. Subsequently, 0.01% (by weight of 1,2-dichloroethane) of glutamic acid porogen was added to 1,2-dichloroethane at 50°C, and the reaction was allowed to proceed for 4 hours. Then, 1% (by weight of 1,2-dichloroethane) of hydroxyethyl sulfonic acid was added to 1,2-dichloroethane, and the reaction was allowed to proceed for 10 hours at 80°C. Finally, the resin was washed 10 times with 5% sodium chloride solution, and the washing solution was washed with deionized water until neutral. Finally, the resin was extracted with ethanol for 40 hours to obtain the modified ion exchange resin.

[0166] During the operation of the above system, the coal gasification wastewater passes through the pipeline sequentially through the 101-filter tank, 110-filter water tank, 105-first impurity removal adsorption tank, and 102-calcium and magnesium element adsorption tank before entering the 111-hard water removal tank. The hard water is then either sent to the subsequent biochemical system or returned to the coal gasification system.

[0167] After the resin in the 102-calcium and magnesium element adsorption tank becomes saturated, it needs to be regenerated. During the regeneration process, brine with a salt content >10% and TOC <15mg / L is introduced into the 106-ozone treatment tank. Ozone is first introduced into the brine to oxidize the TOC in the brine. The ozone dosage is 5kg / m³. 3The oxidation time was 1 hour, and the TOC after oxidation was <8 mg / L. The oxidized brine entered the 107-second impurity removal adsorption tank to remove metal impurities from the brine, and then obtained regenerated water for regenerating the resin in the 102-calcium and magnesium element adsorption tank. Specifically, the resin in the 102-calcium and magnesium element adsorption tank was first washed with demineralized water at 2 bv / h for 2 hours, then washed with brine diluted with demineralized water at 1 bv / h for 2 hours, with the dilution ratio of demineralized water to brine being 1:2; finally, it was washed with demineralized water at 2 bv / h for 2 hours.

[0168] The regenerated wastewater after regeneration treatment has a Ca content of 9140 mg / L, an ammonia nitrogen content of 834 mg / L, and a TOC content of 9.5 mg / L. The regenerated wastewater is transported from tank 108 to ammonia stripping tower 109 for treatment. First, the pH of the regenerated wastewater is adjusted to 12 using 32% sodium hydroxide. Then, it enters the ammonia stripping tower 109, which uses a cross-flow tray design with 30 trays for ammonia removal. The bottom outlet of the ammonia stripping tower 109 is connected to a sea discharge pipeline, and the ammonia-removed regenerated wastewater is discharged into the sea.

[0169] The antifouling filter media in filter tank 101 needs to be backwashed periodically. During the backwashing process, the filtered water stored in filter water tank 110 enters filter tank 101 through the backwash water inlet, fluidizing the antifouling filter media to 100% expansion height. The fluidized antifouling filter media is then transported to filter media scrubber 103 by a high-speed centrifugal pump. Under the rotational friction action at 300 rpm, the contaminants in the filter media are broken down into suspended solids and returned to filter tank 101 for backwashing removal. The contaminants and backwash water enter backwash water collection tank 112 through the backwash water outlet of filter tank 101.

[0170] In this embodiment, the hard water obtained has SS < 3 mg / L and total hardness < 10 mg / L, meeting the biochemical and system reuse acceptance criteria. After 500 backwashes in the 102-calcium-magnesium element adsorption tank, the filtration flux decreased by 1%. After regeneration with brine that has undergone ozone treatment and pretreatment with the second metal element adsorption, the resin adsorption capacity in the 102-calcium-magnesium element adsorption tank recovered to 99.8%, and the resin adsorption regeneration life was > 600 cycles, effectively alleviating the scaling problem of the coal gasification unit. After ammonia stripping treatment, the regenerated wastewater has ammonia nitrogen < 1 mg / L and TOC < 10 mg / L, meeting the requirements for discharge into the sea.

[0171] Example 2

[0172] The antifouling glass filter media, the preparation method of the modified ion exchange resin, and the process flow used in this embodiment are consistent with those in Example 1, with adjustments only made to the wastewater source and operating parameters. The wastewater used in this embodiment is taken from the outlet wastewater of the black water settling tank of the coal gasification unit in the Yantai Industrial Park of Wanhua Chemical Group Co., Ltd., with a wastewater treatment capacity of 90 m³. 3 / h, the wastewater contains 400mg / L of calcium ions, 30mg / L of magnesium ions, and 700mg / L of COD.

[0173] The regenerated wastewater obtained after regeneration treatment has a Ca content of 9140 mg / L, an ammonia nitrogen content of 834 mg / L, and a TOC content of 9.5 mg / L. The regenerated wastewater is transported to the 109 ammonia stripping tower for treatment via the 108-regenerated wastewater tank. The pH of the regenerated wastewater is first adjusted to 12 using 32% sodium hydroxide, and then it enters the 109-ammonia stripping tower. The 109-ammonia stripping tower uses a cross-flow tray with 30 trays for ammonia removal treatment of the regenerated wastewater.

[0174] After treatment by this invention, SS < 3 mg / L, total hardness < 10 mg / L, and the treated wastewater has virtually no hardness, meeting the biochemical and system reuse acceptance indicators. After 500 backwashes in the 102-calcium-magnesium element adsorption tank, the filtration flux decreases by 0.5%. After regeneration using brine that has undergone ozone treatment and pretreatment with the second metal element adsorption, the resin adsorption capacity in the 102-calcium-magnesium element adsorption tank recovers to 99.1%, and the resin adsorption regeneration life is > 550 cycles, effectively alleviating the scaling problem in the coal gasification unit. After ammonia stripping treatment, the ammonia nitrogen in the regenerated liquid is < 1 mg / L, and the TOC is < 10 mg / L, meeting the requirements for discharge into the sea.

[0175] Comparative Example 1

[0176] The wastewater used in this comparative example was taken from the outlet wastewater of the coal gasification black water settling tank of Wanhua Chemical (Fujian) Co., Ltd. The wastewater treatment capacity was 80 m3 / h, the calcium ion content was 450 mg / L, the magnesium ion content was 24 mg / L, and the COD was 600 mg / L.

[0177] The system used in this comparative example does not include 104 - the agitator, nor 103 - the filter media scrubber.

[0178] Fill 10m into filter tank 101 3 Quartz sand filter media is used to replace anti-fouling filter media. Its particle size is 0.4mm to 0.8mm, the filter media filling height is 800mm, and the filtration setting is a linear velocity of 8m / h.

[0179] The operating parameters of filter tank 101 are controlled as follows: operating pressure 0.2MPa, filtration time 7h, backwash time 30min, and the backwash process consists of 10min of air backflushing, 15min of water backwashing, and 5min of forward washing. The SS of the coal gas wastewater obtained after filtration is <10mg / L. After 500 backwashes of filter tank 101, the filtration flux decreases by 30%. This indicates that when the system does not include impeller 104 or filter media scrubber 103, the performance of filter tank 101 degrades rapidly and cannot meet the long-term stable operation requirements for hardening removal of coal gasification wastewater.

[0180] 102-Calcium and magnesium element adsorption tank is filled with 20m 3 The HYA-10 cation exchange resin discarded from the desalination plant adsorbs calcium and magnesium ions in the wastewater. Each adsorption cycle takes 10 hours to complete, and the total hardness of the effluent is <30 mg / L. Part of the treated wastewater is discharged to the biological system, and the remainder is returned to the gasification system.

[0181] Untreated brine with a salt content >10% was used as the resin regenerator. After the resin was saturated, it was first washed with desalinated water at 2 bv / h for 2 hours, followed by washing with concentrated brine at 1 bv / h for 2 hours, and finally washed with water at 2 bv / h for 2 hours to complete resin regeneration. After brine regeneration, the resin adsorption capacity recovered to 96.5%, and the resin adsorption regeneration life was >300 cycles. It can be seen that the capacity recovery rate and resin adsorption regeneration life in this comparative example are relatively low.

[0182] The regenerated wastewater obtained from the regeneration treatment had a Ca content of 8100 mg / L, an ammonia nitrogen content of 951 mg / L, and a TOC content of 8.7 mg / L. The regenerated wastewater was then transported to a 109-ammonia stripping tower for treatment. First, a 32% sodium hydroxide aqueous solution was used to adjust the pH of the regenerated wastewater to 12 before it entered the 109-ammonia stripping tower, which uses a cross-flow tray design with 30 trays. The regenerated wastewater underwent ammonia removal treatment. After ammonia removal treatment, the ammonia nitrogen content in the regenerated liquid was <1 mg / L, and the TOC content was <10 mg / L, meeting the requirements for discharge into the sea.

[0183] Comparative Example 2

[0184] The wastewater used in this embodiment is taken from the outlet wastewater of the black water settling tank of the coal gasification unit in the Yantai Industrial Park of Wanhua Chemical Group Co., Ltd., with a wastewater treatment capacity of 90m³. 3 / h, the wastewater contains 400mg / L of calcium ions, 30mg / L of magnesium ions, and 700mg / L of COD.

[0185] The system used in this comparative example does not include 104 - the agitator, nor 103 - the filter media scrubber.

[0186] Fill 10m into filter tank 101 3Quartz sand filter media is used to replace anti-fouling filter media. Its particle size is 0.4mm to 0.8mm, the filter media filling height is 800mm, and the filtration setting is a linear velocity of 9m / h.

[0187] The operating parameters of filter tank 101 are controlled as follows: operating pressure 0.2MPa, filtration time 7h, backwash time 30min, and the backwash process consists of 10min of air backflushing, 15min of water backwashing, and 5min of forward washing. The SS of the gasified wastewater obtained after filtration is <10mg / L. After 500 backwashes of filter tank 101, the filtration flux decreases by 28%. This indicates that when the system does not include impeller 104 or filter media scrubber 103, the performance of filter tank 101 degrades rapidly and cannot meet the long-term stable operation requirements for hardening removal of gasified wastewater.

[0188] 102-Calcium and magnesium element adsorption tank is filled with 20m 3 The HYA-10 cation exchange resin discarded from the desalination plant adsorbs calcium and magnesium ions in the wastewater. Each adsorption cycle takes 12 hours to complete, and the total hardness of the effluent is <30 mg / L. Part of the treated wastewater is discharged to the biological system, and the remainder is returned to the gasification system.

[0189] Untreated brine with a salt content >10% was used as the resin regenerator. After the resin was saturated, it was first washed with desalinated water at 2 bv / h for 2 hours, followed by washing with concentrated brine at 1 bv / h for 2 hours, and finally washed with water at 2 bv / h for 2 hours to complete resin regeneration. After brine regeneration, the resin adsorption capacity recovered to 95.3%, and the resin adsorption regeneration life was >280 cycles. It can be seen that the capacity recovery rate and resin adsorption regeneration life are relatively low in this comparative example.

[0190] The regenerated resin rehydration solution contained 8200 mg / L of Ca, 911 mg / L of ammonia nitrogen, and 9.2 mg / L of TOC. The rehydration solution was then transported to a 109-ammonia stripping tower for treatment. First, a 32% sodium hydroxide aqueous solution was used to adjust the pH of the regenerated wastewater to 12 before it entered the 109-ammonia stripping tower. The 109-ammonia stripping tower used a cross-flow tray design with 30 trays. The regenerated wastewater underwent ammonia removal treatment. After ammonia removal treatment, the ammonia nitrogen content in the rehydration solution was <1 mg / L, and the TOC content was <10 mg / L, meeting the requirements for discharge into the sea.

[0191] Test case

[0192] 1. Take the antifouling glass filter media used in Example 1, the quartz sand filter media used in Comparative Example 1, and the AFM glass filter media used to prepare the antifouling glass filter media used in Example 1, and use a BELSORP MINI X specific surface area tester from Microtrabel to test the specific surface area. The test results are shown in Table 1.

[0193] Table 1 Specific surface area data of filter media

[0194]

[0195] As shown in Table 1, the anti-fouling glass filter media has a higher specific surface area than both quartz sand filter media and AFM filter media.

[0196] 2. Take the antifouling glass filter media used in Example 1, the quartz sand filter media used in Comparative Example 1, and the AFM glass filter media used to prepare the antifouling glass filter media used in Example 1, and perform ZETA potential tests. The test results are shown in Table 2.

[0197] The testing method is as follows:

[0198] The zeta potential of the filter media was tested using a SurPASS solid surface potential analyzer. Specifically, a 1 mmol / L potassium chloride electrolyte was circulated through a sample cell containing the test sample to create a flow pressure difference, and the zeta potential was measured by electrodes on both sides of the sample.

[0199] Table 2 ZETA Filter Media Potential Data

[0200]

[0201] As shown in Table 2, the anti-fouling glass filter media has a higher ZETA potential than both quartz sand filter media and AFM filter media.

[0202] 3. Take the anti-fouling glass filter media used in Example 1, the quartz sand filter media used in Comparative Example 1, and the AFM glass filter media used to prepare the anti-fouling glass filter media used in Example 1, and conduct filter media performance tests. The test results are shown in Table 3.

[0203] The testing method is as follows:

[0204] Different types of filter media were loaded into the filter columns for filtration testing. Wastewater containing 50 mg / L SS was introduced into each filter column at a filtration linear velocity of 10 m / h and filtered for 20 hours. The filtered water was taken at each cycle for effluent SS testing. The effluent SS was then enriched by vacuum filtration and the effluent SS particle size distribution was tested using a laser particle size distribution instrument. Subsequently, backwashing and regeneration were performed according to the backwashing conditions of each filter media. After regeneration, the filtration cycle was repeated for 20 cycles. Then, the mud content of each filter media was tested.

[0205] Table 3 Comparison of filter media performance

[0206]

[0207] As shown in Table 3, the anti-fouling glass filter media has higher filtration performance than both quartz sand filter media and AFM filter media.

[0208] 4. Take the modified ion exchange resin used in Example 1, as well as the waste HYA-10 cation exchange resin and fresh HYA-10 cation exchange resin used to prepare the modified ion exchange resin, and conduct resin performance tests. The test results are shown in Table 4.

[0209] The testing method is as follows:

[0210] Take 100 ml of different types of resin and pack them into the adsorption column. Pass an aqueous solution containing 1000 mg / L calcium chloride into each resin column until each resin column is saturated and breaks through. Regenerate the resin with 5% hydrochloric acid and calculate the adsorption capacity of the corresponding resin based on the calcium ion concentration in the regeneration solution.

[0211] Table 4 Comparison of Resin Properties

[0212] Waste HYA-10 cation exchange resin 21.6 Modified ion exchange resin 32.2 Fresh HYA-10 cation exchange resin 33.5

[0213] As shown in Table 4, the modified ion exchange resin has a higher adsorption capacity than the waste resin.

[0214] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0215] First, this invention provides a pretreatment method for coal gasification wastewater with high suspended solids and high hardness. After treatment by this invention, the SS of the coal gasification wastewater is less than 3 mg / L, the total hardness is less than 10 mg / L, and the treated wastewater has virtually no hardness, which can effectively alleviate the scaling problem of coal gasification equipment.

[0216] Secondly, the present invention provides a method for treating anti-fouling filter media and a method for deep cleaning filter media. The anti-fouling filter media itself will not form scale or become contaminated after chemical modification and plasma jet treatment. The caking formed by the filter media trapping suspended matter can be removed by a combination of stirring, crushing and scrubbing, which can ensure that the filter media always remains clean.

[0217] Third, the present invention provides a method for modifying waste ion exchange resin. By performing post-crosslinking, secondary pore formation and sulfonation treatment on the waste ion exchange resin, a modified ion exchange resin with high specific surface area and adsorption capacity is prepared for calcium and magnesium ion adsorption treatment.

[0218] Fourth, the present invention provides a method for using brine as a resin regenerator. The brine is used as a resin regenerator after ozone oxidation and resin impurity removal, which reduces the risk of resin contamination by impurities in the brine. Moreover, the brine regeneration process is safer and simpler than the common acid-base regeneration of resin.

[0219] Finally, this invention provides a method for treating resin regenerated liquid discharged into the sea. It uses ammonia stripping to remove high ammonia nitrogen from the regenerated wastewater, solving the problem that high-salt, high-ammonia nitrogen wastewater cannot be treated by biochemical methods, and achieving the standard discharge of resin regenerated liquid into the sea.

[0220] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the technical solutions of the embodiments of the present invention.

Claims

1. A method for removing hardness from coal gasification wastewater, characterized in that, The process includes the following steps: sequentially subjecting coal gasification wastewater to anti-fouling filter media filtration and calcium and magnesium adsorption treatment to obtain de-hardened water; The antifouling filter media is prepared using a method comprising the following process: The AFM glass filter media is brought into contact with an alkaline substance and subjected to alkaline etching treatment to obtain the alkaline etching product. The alkaline etching product is contacted with an organic amine and then calcined to obtain an organic amine pore-expanding product. The organic amine pore-expanding product is subjected to plasma jet treatment to obtain the antifouling filter material; The calcium and magnesium adsorption treatment is performed using ion exchange resin. It also includes using a modified ion exchange resin to perform the calcium and magnesium adsorption treatment; The modified ion exchange resin is prepared by a method comprising the following process: The raw cation exchange resin was contacted with 1,2-dichloroethane to perform a first swelling treatment, thereby obtaining a first swollen product. The first swollen product was contacted with an iron salt to obtain a first intermediate; The first intermediate was contacted with 1,2-dichloroethane to undergo a second swelling treatment, resulting in a second swollen product. The second swelling product is contacted with an amino acid porogen and hydroxyethyl sulfonic acid to obtain the modified ion exchange resin. The first swelling treatment is carried out at a temperature of 70-90℃ for 5-15 hours. The second swelling treatment is carried out at a temperature of 70-90℃ for 5-15 hours. The iron salt is selected from at least one of ferric chloride and ferric sulfate; The amino acid porogen is selected from at least one of glutamic acid, arginine, aspartic acid, and leucine.

2. The method for removing hardness from coal gasification wastewater according to claim 1, characterized in that, The calcination treatment is carried out at a temperature of 300-500℃ for 2-4 hours. The plasma jet treatment has a processing voltage of 8~12kV and a processing time of 1-3h.

3. The method for removing hardness from coal gasification wastewater according to claim 1 or 2, characterized in that, Before performing the calcium and magnesium element adsorption treatment, the product obtained from the filtration treatment is further subjected to a first impurity removal adsorption treatment.

4. The method for removing hardness from coal gasification wastewater according to claim 1 or 2, characterized in that, The raw material cation exchange resin is waste cation exchange resin from the desalination process; It also includes regenerating the ion exchange resin after the calcium and magnesium adsorption treatment by using brine that has undergone ozone treatment and a second impurity removal adsorption treatment in sequence to obtain regenerated wastewater. It also includes ammonia removal treatment of the regenerated wastewater.

5. A hardness removal treatment apparatus for coal gasification wastewater used in performing the hardness removal treatment method for coal gasification wastewater according to any one of claims 1-4, characterized in that, It includes interconnected filter tanks and calcium and magnesium element adsorption tanks; The filter canister includes the anti-fouling filter media, and the calcium and magnesium element adsorption canister includes the ion exchange resin.

6. The hardness removal treatment device for coal gasification wastewater according to claim 5, characterized in that, It also includes a filter media scrubber, the inlet of which is connected to the filter media outlet of the filter tank, and the outlet of which is connected to the filter media inlet of the filter tank; The filter tank is provided with an anti-fouling filter material layer composed of the anti-fouling filter material, and the thickness of the anti-fouling filter material layer is 80-120cm. The filter media outlet of the filter can is located below the filter media inlet of the filter can.

7. The hardness removal treatment device for coal gasification wastewater according to claim 6, characterized in that, The filter tank also includes a stirring paddle, which includes stirring blades that are in contact with the anti-fouling filter media layer.

8. The hardness removal treatment device for coal gasification wastewater according to claim 5 or 6, characterized in that, It also includes a first impurity removal adsorption tank, and the filter tank is connected to the calcium and magnesium element adsorption tank through the first impurity removal adsorption tank; It also includes an ozone treatment tank and a second impurity removal adsorption tank that are interconnected, with the outlet of the second impurity removal adsorption tank connected to the reclaimed water inlet of the calcium and magnesium element adsorption tank. It also includes a regenerated wastewater tank and an ammonia stripping tower. The inlet of the regenerated wastewater tank is connected to the regenerated wastewater outlet of the calcium and magnesium element adsorption tank, and the outlet of the regenerated wastewater tank is connected to the inlet of the ammonia stripping tower.

9. The hardness removal treatment device for coal gasification wastewater according to claim 5 or 6, characterized in that, It also includes a water filter tank, the inlet of which is connected to the water filter outlet of which is connected to the backwash water inlet of which is connected to the backwash water inlet of which is connected to the water filter outlet of which is connected to the water filter inlet of which is connected to the water filter outlet of which is connected to the water filter inlet of which is connected to the calcium and magnesium adsorption tank. It also includes a water hardening tank, the inlet of which is connected to the water hardening outlet of the calcium and magnesium adsorption tank. It also includes a backwash water collection tank, the inlet of which is connected to the backwash water outlet of the filter tank.

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