Chemical conditioner for removing ammonia nitrogen from alkali residue

Abstract

The application provides a chemical conditioner for removing ammonia nitrogen from alkali residue, and belongs to the field of industrial solid waste treatment. The chemical conditioner is uniformly mixed by an ammonia nitrogen removal component, an excitation component and a chelating component, wherein the ammonia nitrogen removal component is 0.50-0.80 parts, the excitation component is 0.15-0.40 parts, and the chelating component is 0.05-0.10 parts. The chemical conditioner improves the calcium-magnesium ratio and pH in the alkali residue liquid, promotes the formation of magnesium ammonium phosphate precipitate, speeds up the denitrification speed of the alkali residue liquid, solves the denitrification treatment problem of the conventional chemical precipitation method in the alkali residue liquid, and realizes the rapid treatment of the alkali residue liquid.

Description

Technical Field

[0001] This invention relates to the field of industrial solid waste treatment, and in particular to a chemical conditioner for removing ammonia nitrogen from alkaline slag. Background Technology

[0002] Soda ash is a crucial chemical raw material, often referred to as the "mother of chemicals," and is widely used in light industry, building materials, chemicals, food, metallurgy, textiles, petroleum, and pharmaceuticals. In my country, the main production method for soda ash is the ammonia-soda process, which uses ammonia gas to adjust the pH of the solution to absorb carbon dioxide and produce soda ash. However, producing 1 ton of soda ash generates 0.3 tons of industrial alkali residue, and simultaneously discharges 10 cubic meters of wastewater. 3 The alkali residue liquid has excessive ammonia nitrogen content. Due to the difficulty in dewatering and utilizing the alkali residue, most alkali production enterprises use dams to store the difficult-to-treat alkali residue and alkali residue liquid, forming paste-like alkali residue lakes and alkali residue mountains, resulting in a waste of land resources. After years of accumulation, the volume of alkali residue and alkali residue liquid is enormous, posing a risk of dam failure, and with the tightening of environmental protection policies, rapid remediation is urgently needed.

[0003] Commonly used deammoniation methods include biological methods, physical methods, and chemical methods.

[0004] Biological methods primarily utilize microbial nitrification and denitrification to oxidize ammonia nitrogen into nitrite nitrogen. Nitrite is further oxidized into nitrate, and finally, nitrate is reduced back to nitrogen gas, thus removing ammonia nitrogen. However, biological methods require the selection of specific bacterial strains and must be carried out under specific water conditions. Alkali residue is high-alkalinity, high-salt wastewater. Microorganisms in such a high-salt environment will die due to plasmolysis caused by dehydration. Even highly salt-tolerant microorganisms cannot multiply rapidly due to the low organic matter content in the alkali residue, which lacks the energy and material necessary for microbial growth. Therefore, biological methods are not suitable for denitrification of alkali residue.

[0005] Physical methods mainly rely on air stripping for nitrogen removal. The basic principle of air stripping for ammonia nitrogen removal is that ammonium ions can be converted into free ammonia in an alkaline environment. Then, through the intense contact between gas and liquid, the free ammonia forms N2, thereby achieving the purpose of removing ammonia nitrogen. The stripping method is simple to operate, has a simple process, and stable treatment effect. It is suitable for the pretreatment of high-concentration ammonia nitrogen wastewater and is currently widely used in the industrial treatment of various high-concentration ammonia nitrogen wastewater. However, the air stripping method is affected by factors such as pH, temperature, gas-liquid ratio, residence time, and packing material in the water body: (1) stripping cannot be carried out when the temperature is below 0℃; (2) the stripping method is not effective for treating medium and low concentration ammonia nitrogen wastewater, and it is difficult to achieve the standard in one stripping operation; (3) the stripping equipment is prone to problems such as packing material fouling during actual application. The concentration of ammonia nitrogen in the alkaline sludge of the ammonia-soda process is not high, usually between 80-300 mg·L. -1Air stripping is not very effective. Furthermore, due to the long residence time, the stripping method is slow for treating accumulated alkaline residue waste liquid in the tens of millions of cubic meters. Large-scale processing in a short time requires large equipment and incurs high costs.

[0006] Chemical methods for treating ammonia nitrogen mainly utilize NH4 + With Mg 2+ and PO4 3- The process involves forming a sparingly soluble double salt, MgNH4PO4·6H2O (magnesium ammonium phosphate, commonly known as struvite, which is sparingly soluble in water), to remove ammonia nitrogen. The magnesium ammonium phosphate precipitate obtained from the chemical treatment of ammonia nitrogen wastewater is a slow-release compound fertilizer containing nitrogen, phosphorus, and magnesium, which can be used for crops, turning waste into treasure and achieving the rational and effective utilization of resources. While this method offers rapid and efficient ammonia nitrogen removal, it introduces chloride ions and residual phosphorus, which can easily cause secondary pollution to the environment. Alkali residue contains a large amount of magnesium and ammonia nitrogen, making chemical methods advantageous for ammonia nitrogen removal, as only an external phosphorus source is needed to form struvite precipitate. However, the alkaline residue contains a large amount of calcium salts and other metal ions, which can also react with the added PO42-. 3 - The reaction reduces the ammonia nitrogen removal rate. Summary of the Invention

[0007] In view of this, the present invention provides a chemical conditioner for ammonia nitrogen removal from alkaline residue. This chemical conditioner can effectively improve the calcium-magnesium ratio and pH in the alkaline residue solution to promote the formation of magnesium ammonium phosphate precipitate, accelerate the denitrification speed of the alkaline residue solution, improve treatment efficiency, solve the problem of denitrification treatment of alkaline residue solution by conventional chemical precipitation method, and realize the rapid treatment of alkaline residue solution.

[0008] The chemical conditioning agent for ammonia nitrogen removal from alkaline residue provided by the present invention is characterized by comprising the following components:

[0009] Ammonia nitrogen removal component: 0.50–0.80 parts.

[0010] 0.15–0.40 parts of the activating component;

[0011] Chelating component 0.05–0.10 parts.

[0012] Preferably, the ammonia nitrogen removal component is one or more of sodium hypophosphite, sodium phosphate, sodium metaphosphate, polyhexametaphosphate, potassium dihydrogen phosphate, and dipotassium hydrogen phosphate.

[0013] Preferably, the activating component is one or more of sodium carbonate, sodium sulfate, sodium oxalate, sodium acetate, and sodium silicate.

[0014] Preferably, the chelating component is one or more of sodium alginate, ethylenediaminetetraacetic acid, sodium ethylenediaminetetraacetic acid, citric acid, sodium citrate, ferric citrate, and sodium tartrate.

[0015] The ammonia nitrogen removal chemical conditioner for alkaline sludge provided by this invention has ammonia nitrogen removal components with good pH compatibility, which can effectively provide a phosphorus source. It can react rapidly with ammonium and magnesium ions in the highly alkaline environment of the alkaline sludge, reducing the ammonia nitrogen content of the alkaline sludge solution. Excess phosphorus can also continue to react with calcium insolubles to prevent phosphate pollution of water bodies. The activating components can effectively react with metal ions such as calcium ions in the solution to produce insolubles, playing a role in removing ions and assisting the reaction of ammonia nitrogen removal components, thereby enhancing and accelerating the formation of struvite precipitation. The chelating components can chelate high-valence ions in the alkaline sludge solution, protecting the ammonia nitrogen removal components and improving the calcium-magnesium ratio.

[0016] The present invention also provides a method for preparing an ammonia nitrogen removal chemical conditioner for alkaline residue. The specific steps are as follows: weigh the raw materials of ammonia nitrogen removal component, activation component and chelating component according to the above mass ratio, mix them evenly, and the ammonia nitrogen removal chemical conditioner is obtained.

[0017] According to a specific embodiment of the present invention, in the aforementioned chemical conditioning agent for ammonia nitrogen removal from alkaline residue, mixing is a conventional technical means in the art. During the mixing process, stirring can be performed to ensure that the ammonia nitrogen removal components, activation components, and chelating components are mixed more thoroughly, preventing local agglomeration.

[0018] According to a specific embodiment of the present invention, the order of addition of the ammonia nitrogen removal component, the activating component and the chelating component in the chemical conditioning agent for ammonia nitrogen removal of alkaline residue is not specifically required. Those skilled in the art can reasonably adjust the order of addition of these raw materials according to the needs of on-site operation.

[0019] For example, in a specific embodiment of the present invention, the ammonia nitrogen removal component can be added to the mixer for mixing first, the chelation component can be added to the mixer for mixing second, and the activation component can be added to the mixer for mixing third.

[0020] Compared with the prior art, the present invention has the following beneficial effects: The chemical conditioner in the present invention is mainly composed of ammonia nitrogen removal components, activating components and chelating components uniformly mixed together, which solves the problem of poor denitrification effect of chemical method in the treatment of high calcium and high salt alkaline slag, realizes rapid removal of ammonia nitrogen from alkaline slag liquid, and avoids water pollution by chemical conditioner. Detailed Implementation

[0021] To provide a clearer understanding of the technical features, objectives, and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail with reference to the following specific embodiments, but this should not be construed as limiting the scope of implementation of the present invention.

[0022] Example 1

[0023] A chemical conditioning agent for ammonia nitrogen removal from alkaline residue is composed of the following raw materials:

[0024] Ammonia nitrogen removal components: sodium phosphate, sodium metaphosphate;

[0025] Activating components: sodium oxalate, sodium acetate;

[0026] Chelating component: ethylenediaminetetraacetic acid. Specific proportions of each raw material are shown in Table 1.

[0027] Weigh the raw materials according to the above-mentioned quality, put them into a mixer and mix them. After mixing, a powdered chemical conditioner is formed and stored in a sealed container.

[0028] Weigh out 5‰ of the prepared chemical conditioner according to the mass of the alkali residue, mix it with the alkali residue liquid, stir evenly, and then determine its ammonia nitrogen content.

[0029] Examples 2-5

[0030] The types of raw materials, preparation methods, and application methods in Examples 2-5 are the same as in Example 1, except that the proportions of the raw materials are changed. The proportions of each raw material are shown in Table 1.

[0031] Table 1

[0032]

[0033] Example 6

[0034] A chemical conditioning agent for ammonia nitrogen removal from alkaline residue is composed of the following raw materials:

[0035] Ammonia nitrogen removal components: sodium phosphate, sodium metaphosphate;

[0036] Activating components: sodium oxalate, sodium acetate;

[0037] Chelating component: Sodium citrate. Specific proportions of each raw material are shown in Table 2.

[0038] Weigh the raw materials according to the above-mentioned quality, put them into a mixer and mix them. After mixing, a powdered chemical conditioner is formed and stored in a sealed container.

[0039] Weigh out 5‰ of the prepared chemical conditioner according to the mass of the alkali residue, mix it with the alkali residue slurry, stir evenly, and then determine its ammonia nitrogen content.

[0040] Examples 7-8

[0041] The types of raw materials, preparation methods, and application methods in Examples 7 and 8 are the same as in Example 6, except that the proportions of the raw materials are changed. The proportions of each raw material are shown in Table 2.

[0042] Table 2

[0043]

[0044]

[0045] Example 9

[0046] A chemical conditioning agent for ammonia nitrogen removal from alkaline residue is composed of the following raw materials:

[0047] Ammonia nitrogen removal components: sodium phosphate, sodium hypophosphite;

[0048] Activating components: sodium oxalate, sodium acetate;

[0049] Chelating component: Sodium citrate. Specific proportions of each raw material are shown in Table 3.

[0050] Weigh the raw materials according to the above-mentioned quality, put them into a mixer and mix them. After mixing, a powdered chemical conditioner is formed and stored in a sealed container.

[0051] Weigh out 5‰ of the prepared chemical conditioner according to the mass of the alkali residue, mix it with the alkali residue slurry, stir evenly, and then determine its ammonia nitrogen content.

[0052] Examples 10-11

[0053] The types of raw materials, preparation methods, and application methods in Examples 10 and 11 are the same as in Example 9, except that the proportions of the raw materials are changed. The proportions of each raw material are shown in Table 3.

[0054] Table 3

[0055]

[0056] Comparative Example 1

[0057] Sodium phosphate was weighed at 5‰ of the mass of the alkali residue and mixed with the alkali residue slurry. After stirring evenly, its ammonia nitrogen content was measured.

[0058] The results of the addition of chemical conditioners to Examples 1-11 and Comparative Example 1, and the determination of flocculation sedimentation time and volume sedimentation rate are shown in Table 4.

[0059] Table 4

[0060]

[0061]

[0062] The above description is merely an illustrative embodiment of the present invention and is not intended to limit the scope of the invention. The various components of the present invention can be combined with each other without conflict. Any equivalent changes and modifications made by those skilled in the art without departing from the concept and principles of the present invention should fall within the scope of protection of the present invention.

Claims

1. A chemical conditioning agent for ammonia nitrogen removal from alkaline residue, characterized in that, The components include the following parts by weight: Ammonia nitrogen removal component: 0.50–0.80 parts. 0.15–0.40 parts of the activating component; Chelating component 0.05–0.10 parts; The ammonia nitrogen removal component is one or more of sodium hypophosphite, sodium phosphate, sodium metaphosphate, polyhexametaphosphate, potassium dihydrogen phosphate, and dipotassium hydrogen phosphate. The activating component is one or more of sodium carbonate, sodium sulfate, sodium oxalate, sodium acetate, and sodium silicate. The chelating component is one or more of sodium alginate, ethylenediaminetetraacetic acid, sodium ethylenediaminetetraacetic acid, citric acid, sodium citrate, ferric citrate, and sodium tartrate.

2. The preparation method of the chemical conditioner for ammonia nitrogen removal from alkaline residue according to claim 1, characterized in that, The raw materials of ammonia nitrogen removal component, activating component and chelating component weighed according to the above mass proportions are mixed evenly to obtain the ammonia nitrogen removal chemical conditioning agent.

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