Treatment method of high-concentration mixed organic wastewater
By combining alkaline and acidic wet oxidation to treat high-concentration mixed organic wastewater, the problem of difficulty in treating compounds such as phenolic aldehydes and ketones in existing technologies is solved, efficient degradation and salt recycling are achieved, and efficient and economical treatment effects are achieved.
Patent Information
- Application Number
- CN202510868178.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-26
- Publication Date
- 2025-10-17
AI Technical Summary
Existing technologies are difficult to effectively treat high-concentration, multi-component mixed organic wastewater, especially wastewater containing compounds such as phenols, aldehydes and ketones. In addition, wet oxidation technology has limited removal effect on certain compounds in alkaline or acidic environments, making it difficult to meet emission standards.
A method combining alkaline and acidic wet oxidation is adopted. By using different wet oxidation catalysts (such as copper sulfate, ferrous sulfate, copper chloride or ferric chloride) under different pH conditions, the difficult-to-degrade compounds are first treated in an alkaline environment, and then further oxidized in an acidic environment, combined with resin adsorption and evaporation to recover salts.
The degradation rate of organic wastewater is significantly improved, the COD or TOC removal rate reaches more than 99%, meeting the emission standards, and realizing the recycling of salt, which is economically beneficial.
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Abstract
Description
TECHNICAL FIELD
[0001] The present application belongs to the technical field of wastewater treatment, and particularly relates to a treatment method for high-concentration mixed organic wastewater. BACKGROUND
[0002] The wet oxidation technology is a wastewater treatment method for oxidizing and decomposing high-concentration organic pollutants into CO2, water or small-molecule organic matters by using oxygen or air as an oxidant under high temperature (150-320℃) and high pressure (2-20 MPa). The wet oxidation technology has a significant oxidation effect on high-concentration and difficult-to-degrade organic matters (such as phenols, cyanides, polycyclic aromatic hydrocarbons, etc.), and the COD removal rate can reach 70%-80%.
[0003] The pollutants in chemical production wastewater are complex, usually containing multiple types of compounds, and have high concentration, high salt content and difficult biodegradability. The treatment efficiency is low, the treatment cost is high, and the generated salt is treated as hazardous waste by using the conventional combination process of advanced oxidation method, biological method and evaporation. The wet oxidation technology has a high removal rate of organic matters (some can be more than 90%), but for wastewater with COD of several ten thousand mg / L, the single wet oxidation treatment still cannot reach the expected treatment target, and the substances treated by the wet oxidation technology are often difficult to be further degraded, which will bring certain difficulties to the subsequent treatment process. In general, the removal effect of organic matters is higher in an acidic environment, but for wastewater containing aldehydes and ketones, the organic matters are more easily oxidized in an alkaline environment. However, the prior art lacks a good treatment method for such mixed organic wastewater. It is of great significance to develop a treatment process for high-concentration mixed organic wastewater with multiple components. SUMMARY
[0004] The purpose of the present application is to provide a treatment method for high-concentration mixed organic wastewater, which can significantly improve the degradation effect of difficult-to-treat wastewater containing phenolic aldehyde ketone and other organic matters, and the COD of the effluent reaches the discharge standard.
[0005] The technical solution adopted by the present application is as follows: A treatment method for high-concentration mixed organic wastewater, the method comprising the following steps: (1) adjusting the pH value of the high-concentration mixed organic wastewater to 9-13, adding a wet oxidation catalyst A, using oxygen or air as an oxidant, and performing alkaline wet oxidation at a temperature of 220-300℃; (2) adjusting the pH value of the effluent of the alkaline wet oxidation to 1-5, adding a wet oxidation catalyst B, using oxygen or air as an oxidant, and performing acid wet oxidation at a temperature of 220-300℃, so as to obtain treated salt-containing wastewater.
[0006] The wet oxidation catalyst A or B is copper sulfate, ferrous sulfate, copper chloride or iron chloride.
[0007] A and B are used to distinguish the wet oxidation catalysts in different steps and have no chemical meaning.
[0008] The high-concentration mixed organic wastewater generally refers to wastewater with COD greater than 20000 mg / L and / or wastewater with TOC greater than 5000 mg / L.
[0009] The method can further treat wastewater with COD greater than 50000 mg / L.
[0010] The method can also treat wastewater with TOC greater than 5000 mg / L, in particular wastewater with TOC greater than 10000 mg / L or even greater than 20000 mg / L.
[0011] Further, the high-concentration mixed organic wastewater at least includes at least one of aldehydes and ketones, preferably includes at least one of aldehydes and ketones and includes one or two of alcohols, phenols and esters.
[0012] In the step (1), the feeding amount of the wet oxidation catalyst A is 0.001-0.05% of the wastewater mass, preferably 0.005-0.03%, and more preferably 0.005-0.02%.
[0013] In the step (2), the feeding amount of the wet oxidation catalyst B is 0.05-0.5% of the wastewater mass, preferably 0.05-0.3%, and more preferably 0.05-0.2%.
[0014] Generally, the feeding amount of the wet oxidation catalyst B is greater than that of the wet oxidation catalyst A.
[0015] In the step (1), if turbidity and precipitate appear in the wastewater after the pH value is adjusted to 9-13, the solid impurities are removed by filtration, and then the wet oxidation catalyst A is added for alkaline wet oxidation.
[0016] In the step (2), if turbidity and precipitate appear in the wastewater after the pH value is adjusted to 1-5, the solid impurities are removed by filtration, and then the wet oxidation catalyst B is added for alkaline wet oxidation.
[0017] In the step (1), the pH value is generally adjusted to 9-13 by adding alkali, and in the step (2), the pH value is generally adjusted to 1-5 by adding acid. The alkali can be sodium hydroxide or potassium hydroxide, and the acid can be concentrated hydrochloric acid or sulfuric acid.
[0018] The specific acid and base are selected according to the cations and anions contained in the wastewater, for example, if the cation in the wastewater is mainly sodium ion, the base is selected as sodium hydroxide, if the cation is mainly potassium ion, the base is selected as potassium hydroxide.
[0019] If the anion in the wastewater is mainly chloride ion, the acid is selected as concentrated hydrochloric acid, if the anion is mainly sulfate ion, the acid is selected as sulfuric acid.
[0020] Generally, the wastewater contains more sodium ion, chloride ion and sulfate ion, so sodium hydroxide, concentrated hydrochloric acid and sulfuric acid are generally selected to adjust the pH value.
[0021] In the step (1), the pH value is generally adjusted to 9-13 by adding sodium hydroxide, and the pH value is preferably adjusted to 10-13.
[0022] In the step (2), the pH value is generally adjusted to 1-5 by adding concentrated hydrochloric acid or concentrated sulfuric acid, and the pH value is preferably adjusted to 2-4.
[0023] In the step (1), the reaction temperature is preferably 250-280℃, In the step (2), the reaction temperature is preferably 250-280℃.
[0024] In the step (1), the reaction time is 2-5h, preferably 3-4h.
[0025] In the step (2), the reaction time is 2-5h, preferably 3-4h.
[0026] In the step (2), the treated salt-containing wastewater can be treated by resin adsorption to recover the catalyst.
[0027] After the salt-containing wastewater obtained in the step (2) is adjusted to neutral pH value, water can be removed by evaporation to recover the salt. The recovered salt is generally sodium salt, such as sodium chloride, sodium sulfate, etc. Sodium hydroxide is generally added to adjust the pH value to neutral.
[0028] Evaporation can use MVR, multi-effect evaporation and other economical and energy-saving and environmentally friendly evaporation technologies.
[0029] The method of the present application first proposes to combine basic wet oxygen and acidic wet oxygen, first degrades compounds difficult to remove in acidic environment, such as aldehyde and ketone compounds, in basic wet oxygen, and then further degrades organic matter in acidic wet oxygen. After the first step of basic wet oxygen, the removal rate of COD or TOC is 80-90%, and after the second step of acidic wet oxygen, the total removal rate of COD or TOC reaches more than 99%. The method of the present application significantly improves the degradation rate of high-concentration mixed organic wastewater, and the salt in the wastewater can also be recovered in the form of industrial salt, etc. The present application is simple and efficient, economical and environmentally friendly, and has great economic benefit and application value. DETAILED DESCRIPTION
[0030] The technical solutions of the present application are further illustrated below by examples, but the protection scope of the present application is not limited thereto.
[0031] Example 1 Wastewater sample 1: mixed wastewater from a chemical company, containing organic matters such as alcohols, aldehydes, ketones and esters, orange in color, pH = 7.42, COD = 21460 mg / L, TOC = 6385 mg / L, salt content 13.9%, sodium chloride, and the treatment requirement is that the effluent TOC is less than 10 mg / L. The following Table 1 process is used for treatment, and experiments 1-5 are different treatment processes, and the treatment results are shown in Table 1.
[0032] The amount of catalyst in Table 1 refers to the ratio of the mass of catalyst added to the wastewater to the mass of wastewater.
[0033] Among them, the catalyst dosage of acidic wet oxygen is the amount of catalyst newly added in the effluent of alkaline wet oxygen, and the amount of catalyst originally contained in the effluent of alkaline wet oxygen is not counted.
[0034] Table 1 The effluent TOC requirement of this example is less than 10 mg / L, which is high and difficult to achieve with conventional means. The results of experiments 1-4 show that single alkaline wet oxygen or single acidic wet oxygen cannot meet the treatment requirements, and the TOC is more than 100 mg / L, which is difficult to achieve less than 10 mg / L. Among them, experiments 2-4 use acidic wet oxygen, and the catalyst copper chloride has different dosages, but from the results, it can be seen that as the dosage increases, the TOC removal rate increases, but even if the catalyst dosage increases to 0.3%, the TOC removal rate still cannot reach 99%, and the TOC is still more than 100 mg / L.
[0035] Experiment 5 uses the technical solution of the present application, combining alkaline wet oxygen and acidic wet oxygen, and the TOC can meet the company's treatment requirements, with a TOC removal rate of more than 99%, which is significantly better than experiments 1-4, and the catalyst dosage of acidic wet oxygen is lower than that of experiment 3, but achieves better treatment effect. The treated sodium chloride wastewater can be used as raw material for ion exchange membrane caustic soda. Experiment 6 combines alkaline wet oxygen and acidic wet oxygen, and the TOC is also reduced to less than 50 mg / L, with a TOC removal rate of more than 99%. Experiment 5 increases the catalyst dosage compared to experiment 6, and improves the TOC removal rate.
[0036] Example 2 Wastewater sample 2: a company producing pesticide intermediates, containing phenol and ketone wastewater, mainly containing phenolic and ketonic organic matter, light yellow, pH = 3.5, COD = 56350 mg / L, TOC = 21055 mg / L, salt content 19.2%, mainly sodium chloride, the requirement of wet oxygen effluent COD < 250 mg / L, the recovered sodium chloride salt reaches the standard of industrial salt. The following Table 2 process is used for treatment, experiments 7-12 are different treatment processes, and the obtained treatment results are shown in Table 2.
[0037] Table 2 Experiments 7-10 show that the COD removal rates of single alkaline wet oxygen and single acid wet oxygen are all above 90%, but cannot reach 99%, and the wet oxygen effluent COD is as high as 2000 mg / L or more. Experiments 11 and 12 use alkaline wet oxygen and acid wet oxygen in combination, and the COD removal rate is above 99%, and the COD is as low as 250 mg / L or less. The effluent is recovered by resin to recover the catalyst, and then the pH value is adjusted to neutral, and then evaporated and crystallized, and the sodium chloride salt is recovered to reach the standard of industrial salt.
Claims
1. A method for treating high-concentration mixed organic wastewater, characterized in that The method comprises the following steps: (1) Adjust the pH value of high-concentration mixed organic wastewater to 9-13, add wet oxidation catalyst A, use oxygen or air as oxidant, and perform alkaline wet oxidation at a temperature of 220-300°C; (2) The pH value of the alkaline wet oxidation effluent is adjusted to 1-5, a wet oxidation catalyst B is added, oxygen or air is used as an oxidant, and acidic wet oxidation is carried out at 220-300°C to obtain treated saline wastewater.
2. The method according to claim 1, wherein The wet oxidation catalyst A or B is copper sulfate, ferrous sulfate, copper chloride or ferric chloride.
3. The method according to claim 1, wherein The high-concentration mixed organic wastewater refers to wastewater with a COD greater than 20,000 mg / L and / or wastewater with a TOC greater than 5,000 mg / L.
4. The method according to claim 3, wherein The high-concentration mixed organic wastewater includes at least one of aldehydes and ketone compounds.
5. The method according to claim 4, wherein The high-concentration mixed organic wastewater includes at least one of aldehydes and ketone compounds and one or two of alcohols, phenols and esters.
6. The method according to claim 1, wherein In the step (1), the feeding amount of the wet oxidation catalyst A is 0.001-0.05% of the mass of the wastewater; in the step (2), the feeding amount of the wet oxidation catalyst B is 0.05-0.5% of the mass of the wastewater.
7. The method according to claim 1, wherein In the step (1), sodium hydroxide is used to adjust the pH value to 10-13; in the step (2), concentrated hydrochloric acid or concentrated sulfuric acid is added to adjust the pH value to 2-4.
8. The method according to claim 1, wherein In the step (1), the reaction temperature is 250-280°C, and in the step (2), the reaction temperature is 250-280°C.
9. The method according to claim 1, wherein In the step (2), the catalyst is recovered by resin adsorption in the treated salt-containing wastewater.
10. The method according to claim 9, wherein The salt-containing wastewater obtained in step (2) is adjusted to a neutral pH value after the catalyst is recovered, and water is removed by evaporation to recover the salt.