DSD acid oxidation wastewater treatment method and application thereof

Abstract

The present application relates to the technical field of water treatment, in particular to a DSD acid oxidation wastewater treatment method, comprising wastewater extraction, macroporous resin adsorption, iron-carbon microelectrolysis, MVR evaporation concentration; DNS in water is extracted by extractant to prepare DSD acid in DNS reduction section, improve product yield; the remaining DNS is enriched by macroporous resin adsorption, and after elution, DNS can be directly used for reduction to prepare DSD acid, the comprehensive removal rate of CODCr in the first two steps is 90-95%; iron-carbon microelectrolysis is used for advanced treatment, the color of effluent is colorless and transparent, and CODCr is below 100 mg / L; high-quality salt is obtained by MVR concentration, and the evaporated water is used for S2 resin desorption or DSD preparation process; the problem of DSD acid oxidation wastewater treatment is effectively solved.

Description

Technical Field

[0001] This invention relates to the field of water treatment technology, CO2F9 / 00, and particularly to a method for treating DSD acid oxidation wastewater and its application. Background Technology

[0002] DSD acid (4,4'-diaminostilbene-2,2'-disulfonic acid) is an important dye intermediate. Its production process includes: ① sulfonation of p-nitrotoluene (PNT) with fuming sulfuric acid to obtain p-nitrotoluene-o-sulfonic acid (NTS); ② catalytic oxidation of NTS to obtain 4,4'-dinitrostilbene-2,2'-disulfonic acid (DNS acid); ③ catalytic hydrogenation reduction of DNS acid with iron powder, etc., to produce DSD acid.

[0003] In the above process, approximately 20 tons of wastewater will be generated for every ton of DSD acid produced. This wastewater contains a large amount of colored organic compounds containing sulfonic acid groups and nitro groups, as well as a large amount of Cl. - Red SO4 2- The wastewater contains salts, as well as large amounts of waste acid, intermediate products, and byproducts, resulting in extremely high CODcr values ​​(≥20000 mg / L), color (≥15000 times), and salt content. Direct discharge without treatment would severely pollute the environment and endanger human health. However, the organic matter in DSD acid wastewater is highly water-soluble, making it difficult to remove using traditional flocculation methods. Furthermore, its high salinity necessitates extensive dilution with clean water before any biological treatment can proceed, making this wastewater one of the most difficult chemical wastewaters to treat.

[0004] Chinese patent CN113603264A discloses a method for treating wastewater from the DNS acid reduction process. This method involves flocculation and diazo coupling reactions to remove water-soluble sodium 2,4-diaminobenzenesulfonate from the wastewater, while also generating water-insoluble azo compounds, thus improving the resource utilization rate of the wastewater. However, this method is only suitable for wastewater from the reduction process, and its treatment effect on wastewater from the oxidation process and the combined process is not good. Chinese patent CN1156407C discloses a method for treating and utilizing wastewater from the production of 4,4′-dinitrostilbene-2,2′-disulfonic acid. This patent uses a macroporous weak base anion exchange resin fixed bed to adsorb organic matter in the wastewater. The adsorbed effluent is nearly colorless, and the CODcr is reduced from 13,000-18,000 mg / L to 1,000 mg / L, but the CODcr content is still relatively high. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention first provides a method for treating DSD acid oxidation wastewater, mainly comprising complexation extraction, resin adsorption, and multi-effect concentration. The core idea is to recover the valuable intermediate DNS sodium salt (4,4′-dinitrostilbene-2,2′-disulfonate sodium salt) from the wastewater while effectively removing COD and color. Furthermore, the treated wastewater is evaporated via MVR to produce sodium sulfate as a byproduct, generating economic benefits. The distillate is reused in the reaction, improving the resource utilization rate of the wastewater.

[0006] Furthermore, the DSD acid oxidation wastewater treatment method includes the following steps:

[0007] S1. Wastewater extraction: First, extract the acid oxidation wastewater with an extractant to obtain primary wastewater and oil phase. Then, back extract the oil to obtain DNS concentrate. The DNS concentrate is recovered and used in the DNS reduction section to prepare DSD acid.

[0008] S2. Macroporous resin adsorption: Primary wastewater is adsorbed through macroporous resin to obtain secondary wastewater, and then desorbed by desorbent to recover DNS.

[0009] S3, Iron-Carbon Micro-Electrolysis: Iron and carbon are used to treat secondary wastewater through micro-electrolysis, and then inorganic adsorbents are used to treat the wastewater after micro-electrolysis to obtain tertiary wastewater;

[0010] S4, MVR evaporation and concentration: MVR evaporation and concentration of tertiary wastewater to obtain high-quality salt, and the distilled water is used for S2 resin desorption or DSD preparation process.

[0011] Furthermore, the components of the extractant include at least one of organic amine extractants, alcohol extractants, ester extractants, phosphate ester extractants, sulfoxide extractants, ether extractants, and other types of extractants.

[0012] Furthermore, the organic amine extractant includes, but is not limited to, at least one of trioctyldecyl tertiary amine (N235), trialkylmethylamine, quaternary ammonium salt, didecylamine, trioctylamine, trinonylamine, and dodecyl tertiary amine, preferably at least one of trioctyldecyl tertiary amine, quaternary ammonium salt, trioctylamine, and dodecyl tertiary amine.

[0013] Furthermore, the alcohol extractant includes, but is not limited to, at least one of isoamyl alcohol, 2-octanol, isooctanol, and n-octanol.

[0014] Furthermore, the ester extractant includes, but is not limited to, at least one of ethyl acetate, amyl acetate, and butyl acetate.

[0015] Furthermore, the phosphate ester extractant includes, but is not limited to, at least one of di(2-ethylhexyl) hexyl phosphate, dioctyl octyl phosphate, and tributyl phosphate, preferably tributyl phosphate.

[0016] Furthermore, the sulfoxide extractant includes, but is not limited to, at least one of dioctyl sulfoxide, diphenyl sulfoxide, and hydrocarbon sulfoxide.

[0017] Furthermore, the ether extractant includes, but is not limited to, at least one of diisopropyl ether, ethylhexyl ether, and 9-alkenyl-12-hydroxyoctadecanoic acid polyoxyethylene ether-10; preferably 9-alkenyl-12-hydroxyoctadecanoic acid polyoxyethylene ether-10.

[0018] Furthermore, the other types of extractants include, but are not limited to, at least one of toluene, gasoline, kerosene, sulfonated kerosene, and carbon tetrachloride.

[0019] Preferably, the components of the extractant include organic amine extractants or ether extractants.

[0020] Preferably, the extractant further comprises an alcohol extractant or a phosphate extractant.

[0021] Preferably, the components of the extractant also include other types of extractants.

[0022] Preferably, the volume ratio of organic amine extractant or ether extractant, alcohol extractant or phosphate extractant, and other extractants in the extractant is 1-8:1-5:0.5-10, and more preferably 2-6:1-3:1-7.

[0023] In one embodiment, the extractant comprises trioctyldecyl tertiary amine, sec-octanol, and toluene in a volume ratio of 2:1:7.

[0024] In another embodiment, the extractant consists of trioctylamine, isooctyl alcohol, and sulfonated kerosene in a volume ratio of 1:3:6.

[0025] In another embodiment, the extractant comprises trioctyldecyl tertiary amine, tributyl phosphonate, and toluene in a volume ratio of 1:1:8.

[0026] In another embodiment, the extractant consists of dodecyl tertiary amine, n-octanol, and sulfonated kerosene in a volume ratio of 2:3:5.

[0027] In another embodiment, the extractant is composed of 9-alkenyl-12-hydroxyoctadecanoic acid polyoxyethylene ether-10, n-octanol, and sulfonated kerosene, in a volume ratio of 1:3:6.

[0028] Furthermore, the volume ratio of extractant to wastewater in S1 is 1-8:1-6, preferably 1-5:2-3.

[0029] Furthermore, in S1, the extraction temperature is 20-60℃ and the extraction pH is 1-6; the back-extraction temperature is 20-70℃ and the back-extraction pH is 7.5-13.

[0030] This application optimizes the composition of the extractant to effectively extract DNS and increase the extraction yield. It strictly controls the volume ratio of each component in the extractant, ensuring that the interactions between the components and the resulting interfacial tension are within a suitable range. This allows the dispersed droplets to easily coalesce, facilitating the separation of the oil and aqueous phases and enhancing the extraction and separation effect. Extraction and back-extraction temperatures, as well as the pH value of the system, affect the distribution of DNS and other organic substances between the two phases, especially pH, which can cause a tenfold change in the distribution coefficient. This application specifies an extraction temperature of 20-50℃ and an extraction pH of 1-6 with the above-mentioned extractant formulation, effectively improving the separation of DNS from wastewater. Similarly, controlling the back-extraction temperature at 20-60℃ and the back-extraction pH at 8-12 maximizes the recovery and utilization of DNS. Through the optimization of the extraction process, most of the DNS is separated, effectively reducing the CODcr value of the wastewater and achieving the resource utilization of DNS.

[0031] Preferably, the extraction temperature in S1 is 20-50℃, and the extraction pH is 1-6; the back-extraction temperature is 20-60℃, and the back-extraction pH is 8-12.

[0032] In a preferred embodiment, the extraction temperature in S1 is 20-30°C and the extraction pH is 2-5; the back-extraction temperature is 20-30°C and the back-extraction pH is 8-10.

[0033] Furthermore, the macroporous resin is a macroporous weakly basic anion exchange resin, and the macroporous weakly basic anion exchange resin includes at least one of styrene-based, phenolic-based, and acrylic-based resins.

[0034] Furthermore, the macroporous weakly basic anion exchange resin is selected from at least one of D301 resin, D301FC resin, and D311 resin.

[0035] Furthermore, the adsorption temperature in S2 is 0-50℃, and the flow rate of wastewater through the macroporous resin is 0.25-5 BV / h.

[0036] Preferably, the adsorption temperature in S2 is 30-50℃, and the flow rate of wastewater through the macroporous resin is 0.5-2 BV / h.

[0037] Furthermore, in step S2, the desorbent used for desorption is water or dilute alkali, the flow rate of the desorbent is 0.5-6 BV / h, the amount of desorbent is 2-15 BV, and the desorption temperature is 60-100℃.

[0038] This application utilizes macroporous adsorption resin to further separate DNS acid and other organic components from wastewater. Optimizing the adsorption temperature and flow rate can essentially achieve complete extraction of DNS, effectively reducing the technical difficulty of subsequent treatment. It is worth noting that to achieve optimal desorption and improve the utilization rate and resource recovery of resin and DNS, it is necessary to optimize the desorption parameters and achieve a good match with the exchange resin. Controlling the desorption temperature and flow rate provides sufficient kinetic energy to the adsorbed substances, causing them to evaporate from the surface of the macroporous resin into its pore structure and be desorbed with the flow of the mobile phase. However, excessively high desorption temperatures can actually reduce the amount of DNS desorbed. This is because, under low-energy conditions, the interaction between DNS and macroporous resin is generally physical adsorption. However, under higher temperatures and energy conditions, these energies provide conditions for chemical adsorption, which significantly increases the bond energy of the adsorption bonds and increases the difficulty of desorption.

[0039] Furthermore, the alkali concentration in the dilute alkali is 2-6 wt%.

[0040] Preferably, the desorbent flow rate of S2 is 0.5-4 BV / h, and the desorbent dosage is 4-10 BV.

[0041] Furthermore, the iron-carbon is a mixture of iron-based materials and activated carbon, or an iron-carbon filler obtained by sintering iron, carbon, and a metal catalyst.

[0042] Furthermore, the mass ratio of iron to activated carbon in the iron-carbon mixture is 0.1-0.8:1-4, preferably 0.1-0.5:1-2, and more preferably 0.3-1.5.

[0043] Furthermore, the iron-containing material includes, but is not limited to, at least one of iron filings, iron powder, and iron-containing substances, and the activated carbon includes, but is not limited to, at least one of wood-based charcoal, coal-based charcoal, and coconut shell charcoal.

[0044] Furthermore, hydrogen peroxide is introduced during the micro-electrolysis process, with the amount of hydrogen peroxide introduced accounting for 0.05-2% of the mass of the secondary wastewater, preferably 0.2-1%.

[0045] The iron-carbon microelectrolysis process involves oxidation-reduction, electrochemical enrichment, physical adsorption, flocculation and precipitation, electron transfer, and other processes to remove pollutants. Traditional technologies typically use an iron-carbon mass ratio of 1-2:1. However, this application does not achieve satisfactory decolorization and COD reduction results using this traditional ratio. Therefore, this application specifies an iron-to-carbon mass ratio of 0.1-0.5:1-2, more preferably 0.3:1.5, and adds 0.2-1% hydrogen peroxide (based on the secondary wastewater volume) to react with the Fe produced during the microelectrolysis process. 2+The Fenton reaction is formed to improve the degradation efficiency of organic matter. After micro-electrolysis treatment, the wastewater becomes colorless and transparent, and the CODcr is reduced to below 100 mg / L. When the iron-carbon ratio is too small, the number of micro and macroscopic galvanic cells formed in the environment will decrease, and the electric field enrichment and adsorption effect will also weaken, thus affecting the reaction efficiency of micro-electrolysis. When the iron-carbon ratio is too large, iron ions exist in large quantities in the solution, and the acid reaction dominates, which will inhibit the electrochemical reaction and thus lead to a decrease in treatment effect. When the amount of hydrogen peroxide increases, the amount of H₂O· produced by iron-carbon micro-electrolysis also increases, and the oxidative degradation efficiency of organic matter is improved. However, when hydrogen peroxide is in excess, it will react with H₂O· and consume the latter, thereby weakening the strong oxidizing effect of the system.

[0046] Furthermore, the micro-electrolysis process requires aeration, with a pH of 0.5-4 and a micro-electrolysis time of 6-12 hours.

[0047] Furthermore, after the micro-electrolysis treatment in S3, the wastewater after micro-electrolysis is first neutralized and flocculated, and then treated with an inorganic adsorbent.

[0048] Furthermore, the neutralization and flocculation treatment involves adjusting the pH of the wastewater after micro-electrolysis to 6-9, and then adding flocculant to it.

[0049] Furthermore, the flocculant includes, but is not limited to, at least one of polyaluminum chloride (PAC), polyaluminum sulfate (PAS), polyferric chloride (PFC), polyferric sulfate (PFS), polyaluminum ferric sulfate, ferrous chloride, and hydrated ferrous sulfate; the amount of flocculant added is 0.1-1% of the mass of the secondary wastewater, preferably 0.1-0.5%.

[0050] Furthermore, the inorganic adsorbent in S3 includes, but is not limited to, at least one of silica gel, alumina, activated carbon, and diatomaceous earth, preferably including activated carbon.

[0051] Furthermore, the activated carbon includes, but is not limited to, at least one of wood-based charcoal, coal-based charcoal, and coconut shell charcoal.

[0052] Furthermore, the amount of the inorganic adsorbent is 0.2-5% of the mass of the secondary wastewater, preferably 0.5-1%.

[0053] Secondly, this application also provides the application of the DSD acid oxidation wastewater treatment method; the method can be used to treat at least one type of wastewater, including DSD acid oxidation wastewater, sulfonation wastewater or reduction wastewater from DSD acid preparation.

[0054] Beneficial effects

[0055] 1. This application optimizes the composition and dosage of the extractant, the temperature, pH value, and the amount of extractant added in the extraction process, thereby improving the initial recovery of DNS in wastewater and effectively reducing the CODCr value of the wastewater.

[0056] 2. This application matches the optimal adsorption temperature, desorption temperature and desorbent content for a specific macroporous adsorption resin, achieving near-complete separation and recycling of DNS, and further reducing the CODCr value of wastewater.

[0057] 3. This application optimizes the iron-carbon mass ratio in micro-electrolysis and introduces a certain amount of hydrogen peroxide to simultaneously carry out micro-electrolysis and Fenton reaction, which not only makes the wastewater colorless and transparent, but also further reduces the CODCr value of the wastewater to below 100mg / L.

[0058] 4. The treatment method of this application recovers valuable intermediate sodium DNS salt from the wastewater, effectively removes COD and color, and also recovers sodium sulfate, a by-product of MCVR evaporation of the wastewater. The distillate is reused in the reaction, maximizing the resource utilization rate of waste and generating certain economic benefits.

[0059] 5. The treatment method of this application is simple and easy to implement, and has excellent treatment effect. It can be used not only for the treatment of DSD acid oxidation wastewater, but also for the treatment of sulfonation wastewater or reduction wastewater in DSD acid preparation. Detailed Implementation

[0060] Example

[0061] The DSD acid oxidation wastewater (raw water) used in the following examples and comparative examples has a CODcr of 31050 mg / L and a pH of 5.

[0062] Example 1

[0063] This embodiment provides a method for treating DSD acid oxidation wastewater, including the following steps:

[0064] S1. Wastewater Extraction: Sulfuric acid is added to the DSD acid oxidation wastewater to adjust the pH to 2; N235, 2-octanol, and toluene are mixed in a volume ratio of 2:1:7 to prepare the extractant; the DSD acid oxidation wastewater and the extractant are mixed in a volume ratio of 5:1 and subjected to secondary countercurrent extraction at 25°C to obtain primary wastewater and an oil phase; then, the pH of the oil phase (i.e., the extractant phase) is adjusted to 8 with sodium hydroxide for back-extraction to obtain a 70wt% DNS concentrate for use in the DNS reduction section to prepare DSD acid, and the back-extracted oil phase is reused;

[0065] The CODcr of the primary wastewater is 3050 mg / L, and its color is light yellow.

[0066] S2, Macroporous Resin Adsorption: The primary wastewater from S1 is passed through a polystyrene macroporous adsorption resin (D301 resin, resin adsorption 70 times) at 40℃ and 1 BV / h to obtain secondary wastewater; then the adsorbed resin is eluted with 2wt% sodium hydroxide solution at 80℃, with a sodium hydroxide solution volume of 4 BV, to obtain 52wt% DNS concentrate for use in the DNS reduction section to prepare DSD acid, and the eluted macroporous resin is reused.

[0067] The CODcr of the secondary wastewater was 1231 mg / L, and its color was slightly yellowish-green.

[0068] S3. Iron-Carbon Micro-Electrolysis: Secondary wastewater is treated using iron-carbon micro-electrolysis. The mass ratio of secondary wastewater to iron-carbon is 1:2. The iron-carbon mixture is a mixture of iron filings and granular carbon with a mass ratio of 0.3:1.5. The electrolysis time is 6 hours. During micro-electrolysis, 30 wt% hydrogen peroxide is added, accounting for 0.2% of the secondary wastewater mass, in four separate additions. After micro-electrolysis, alkali is added to adjust the pH to neutral (7.0). 0.1% PAC flocculant (by mass of secondary wastewater) is added for flocculation. Then, 1.5% activated carbon (by mass of secondary wastewater) is added for adsorption, resulting in tertiary wastewater.

[0069] The CODcr of the tertiary wastewater was 76 mg / L, and it was colorless and transparent.

[0070] S4, MVR evaporation and concentration: MVR evaporation and concentration of tertiary wastewater to obtain high-quality salt; the distilled water is used for S2 resin desorption or DSD preparation process.

[0071] Example 2

[0072] This embodiment provides a method for treating DSD acid oxidation wastewater, including the following steps:

[0073] S1. Wastewater Extraction: Sulfuric acid was added to the DSD acid oxidation wastewater to adjust the pH to 3; trioctylamine, isooctyl alcohol, and sulfonated kerosene were mixed in a volume ratio of 1:3:6 to prepare the extractant; the DSD acid oxidation wastewater and the extractant were mixed in a volume ratio of 4:1 and subjected to secondary countercurrent extraction at 25°C to obtain primary wastewater and an oil phase; then, the pH of the oil phase (i.e., the extractant phase) was adjusted to 9 with sodium carbonate for back-extraction to obtain a 67wt% DNS concentrate for use in the DNS reduction section to prepare DSD acid, and the back-extracted oil phase was reused;

[0074] The CODcr of the primary wastewater was 2756 mg / L, and its color was pale yellow.

[0075] S2. Macroporous resin adsorption: Primary wastewater is passed through a polystyrene macroporous adsorption resin (D301FC resin, resin adsorption 100 times) at 40℃ and 2BV / h to obtain secondary wastewater; then the adsorbed resin is eluted with a 4wt% sodium hydroxide solution at 70℃, with a sodium hydroxide solution volume of 5BV, to obtain a 55wt% DNS concentrate for use in the DNS reduction section to prepare DSD acid, and the eluted macroporous resin is reused.

[0076] The CODcr of the secondary wastewater was 1240 mg / L, and its color was slightly yellowish-green.

[0077] S3. Iron-Carbon Micro-Electrolysis: Secondary wastewater is treated using iron-carbon micro-electrolysis. The mass ratio of secondary wastewater to iron-carbon is 1:2. The iron-carbon mixture is a mixture of iron filings and granular carbon with a mass ratio of 0.3:1.5. The electrolysis time is 7 hours. During micro-electrolysis, 30 wt% hydrogen peroxide is added, accounting for 0.5% of the secondary wastewater mass, in four separate additions. After micro-electrolysis, alkali is added to adjust the water to neutral (pH 7.0). 0.1% PAC flocculant (by mass of secondary wastewater) is added for flocculation. Then, 1.5% activated carbon (by mass of secondary wastewater) is added for adsorption, resulting in tertiary wastewater.

[0078] The CODcr of the tertiary wastewater was 55 mg / L, and it was colorless and transparent.

[0079] S4, MVR evaporation and concentration: MVR evaporation and concentration of tertiary wastewater to obtain high-quality salt; the distilled water is used for S2 resin desorption or DSD preparation process.

[0080] Example 3

[0081] This embodiment provides a method for treating DSD acid oxidation wastewater, including the following steps:

[0082] S1. Wastewater Extraction: Hydrochloric acid was added to the DSD acid oxidation wastewater to adjust the pH to 2; N235, tributyl phosphate, and toluene were mixed in a volume ratio of 1:1:8 to prepare the extractant; the DSD acid oxidation wastewater and the extractant were mixed in a volume ratio of 3:1 and subjected to secondary countercurrent extraction at 25°C to obtain primary wastewater and an oil phase; then, the pH of the oil phase (i.e., the extractant phase) was adjusted to 10 with sodium hydroxide for back-extraction to obtain a 65wt% DNS concentrate for use in the DNS reduction section to prepare DSD acid, and the back-extracted oil phase was reused;

[0083] The CODcr of the primary wastewater was 2756 mg / L, and its color was pale yellow.

[0084] S2. Macroporous resin adsorption: Primary wastewater is passed through an acrylic macroporous adsorption resin (D311 resin, resin adsorption 85 times) at 40℃ and 1 BV / h to obtain secondary wastewater; then the adsorbed resin is eluted with 6 wt% sodium hydroxide solution at 80℃, with a sodium hydroxide solution volume of 5 BV, to obtain 55 wt% DNS concentrate for use in the DNS reduction section to prepare DSD acid, and the eluted macroporous resin is reused.

[0085] The CODcr of the secondary wastewater was 1154 mg / L, and its color was slightly yellowish-green.

[0086] S3. Iron-Carbon Micro-Electrolysis: Secondary wastewater is treated using iron-carbon micro-electrolysis, with a wastewater-to-iron-carbon mass ratio of 1:2. The iron-carbon mixture is a mixture of iron filings and granular carbon with a mass ratio of 0.3:1.5. The electrolysis time is 6 hours. During micro-electrolysis, 30 wt% hydrogen peroxide is added, accounting for 0.6% of the secondary wastewater mass, in four separate additions. After micro-electrolysis, alkali is added to adjust the water to neutral (pH 7.0). 0.1% PAC flocculant (by mass of secondary wastewater) is added for flocculation; then 1.5% activated carbon (by mass of wastewater) is added for adsorption, resulting in tertiary wastewater.

[0087] The CODcr of the tertiary wastewater was 58 mg / L, and it was colorless and transparent.

[0088] S4, MVR evaporation and concentration: MVR evaporation and concentration of tertiary wastewater to obtain high-quality salt; the distilled water is used for S2 resin desorption or DSD preparation process.

[0089] Example 4

[0090] This embodiment provides a method for treating DSD acid oxidation wastewater, including the following steps:

[0091] S1. Wastewater Extraction: Dodecyl tertiary amine, n-octanol, and sulfonated kerosene were mixed in a volume ratio of 2:3:5 to prepare the extractant; DSD acid oxidation wastewater was mixed with the extractant in a volume ratio of 3:1 and subjected to secondary countercurrent extraction at 25°C to obtain primary wastewater and an oil phase; then, the pH of the oil phase (i.e., the extractant phase) was adjusted to 10 with sodium hydroxide for back-extraction to obtain a 65wt% DNS concentrate for use in the DNS reduction section to prepare DSD acid, and the back-extracted oil phase was reused;

[0092] The CODcr of the primary wastewater was 1706 mg / L, and its color was pale yellow.

[0093] S2. Macroporous resin adsorption: Primary wastewater is passed through an acrylic macroporous adsorption resin (D311 resin, resin adsorption 100 times) at 40℃ and 1 BV / h to obtain secondary wastewater; then the adsorbed resin is eluted with 80℃ and 4wt% sodium hydroxide solution, with a sodium hydroxide solution volume of 6 BV, to obtain 58wt% DNS concentrate for use in the DNS reduction section to prepare DSD acid, and the eluted macroporous resin is reused.

[0094] The CODcr of the secondary wastewater was 1154 mg / L, and its color was slightly yellowish-green.

[0095] S3, Iron-Carbon Micro-Electrolysis: Wastewater from S2 is treated using iron-carbon micro-electrolysis. The mass ratio of secondary wastewater to iron-carbon is 1:2. Iron-carbon is a filler obtained by sintering iron, carbon, and their metal catalysts, with a mass ratio of iron to carbon of 4:1. The micro-electrolysis time is 10 hours. During the micro-electrolysis process, 30 wt% hydrogen peroxide is added, accounting for 0.8% of the secondary wastewater mass, in four separate additions. After micro-electrolysis, alkali is added to adjust the water to neutral (pH 7.0). 0.1% PFS flocculant (by mass of secondary wastewater) is added for flocculation; then 1.5% activated carbon (by mass of secondary wastewater) is added for adsorption, resulting in tertiary wastewater.

[0096] The CODcr of the tertiary wastewater is 50 mg / L, and it is colorless and transparent.

[0097] S4, MVR evaporation and concentration: MVR evaporation and concentration of tertiary wastewater to obtain high-quality salt; the distilled water is used for S2 resin desorption or DSD preparation process.

[0098] Example 5

[0099] This embodiment provides a method for treating DSD acid oxidation wastewater, including the following steps:

[0100] S1. Wastewater Extraction: 9-Alkenyl-12-hydroxyoctadecanoic acid polyoxyethylene ether-10, n-octanol, and sulfonated kerosene were mixed in a volume ratio of 1:3:6 to prepare an extractant. DSD acid oxidation wastewater was mixed with the extractant in a volume ratio of 5:2 and subjected to secondary countercurrent extraction at 25°C to obtain primary wastewater and an oil phase. The pH of the oil phase (i.e., the extractant phase) was then adjusted to 10 with sodium hydroxide for back-extraction to obtain a 68wt% DNS concentrate, which was used in the DNS reduction section to prepare DSD acid. The back-extracted oil phase was reused.

[0101] The CODcr of the primary wastewater was 1706 mg / L, and its color was pale yellow.

[0102] S2. Macroporous resin adsorption: Primary wastewater is passed through an acrylic macroporous adsorption resin (D311 resin, resin adsorption 100 times) at 40℃ and 1 BV / h to obtain secondary wastewater; then the adsorbed resin is eluted with 4 wt% sodium hydroxide solution at 80℃, with the amount of sodium hydroxide solution being 4 BV, to obtain 58 wt% DNS concentrate for use in the DNS reduction section to prepare DSD acid, and the eluted macroporous resin is reused.

[0103] The CODcr of the secondary wastewater was 1154 mg / L, and its color was slightly yellowish-green.

[0104] S3. Iron-Carbon Micro-Electrolysis: Secondary wastewater is treated using iron-carbon micro-electrolysis, with a wastewater-to-iron-carbon mass ratio of 1:2. Iron-carbon is a filler obtained by sintering iron, carbon, and their metal catalysts, with an iron-to-carbon mass ratio of 4:1. The micro-electrolysis time is 10 hours. During micro-electrolysis, 30 wt% hydrogen peroxide is added, accounting for 0.8% of the secondary wastewater mass, in four separate additions. After micro-electrolysis, alkali is added to adjust the pH to neutral (pH 7.0). 0.1% PFS flocculant (by mass of secondary wastewater) is added for flocculation; then 1.5% activated carbon (by mass of secondary wastewater) is added for adsorption, resulting in tertiary wastewater.

[0105] The CODcr of the tertiary wastewater was 62 mg / L, and it was colorless and transparent.

[0106] S4, MVR evaporation and concentration: MVR evaporation and concentration of tertiary wastewater to obtain high-quality salt; the distilled water is used for S2 resin desorption or DSD preparation process.

[0107] Comparative Example 1

[0108] It is basically the same as Example 4, except that the volume ratio of dodecyl tertiary amine, n-octanol and sulfonated kerosene in the extractant is 7:3:8.

[0109] The CODcr of the primary wastewater was 3421 mg / L, an emulsion layer appeared, the O / A phase separation time was long, and the aqueous phase was mixed with the oil phase.

[0110] Comparative Example 2

[0111] It is basically the same as Example 4, except that the extraction temperature in S1 is 60°C.

[0112] The CODcr of the primary wastewater is 3520 mg / L, and the color is dark yellow; the CODcr of the secondary wastewater is 2115 mg / L, and the color is yellow. The D311 resin adsorbs 85 times the amount of CODcr; the CODcr of the tertiary wastewater is 120 mg / L, and the color is light yellow-green, almost colorless and transparent.

[0113] Comparative Example 3

[0114] It is basically the same as Example 3, except that the mass ratio of iron filings to granular carbon in the iron-carbon mixture is 1:1.

[0115] The CODcr of the tertiary wastewater was 865 mg / L, and its color was pale yellow.

[0116] Comparative Example 4

[0117] It is basically the same as Example 4, except that the total amount of hydrogen peroxide used in S3 accounts for 3% of the mass of secondary wastewater.

[0118] The CODcr of the tertiary wastewater was 175 mg / L, and its color was nearly colorless and transparent.

[0119] Comparative Example 5

[0120] It is basically the same as Example 4, except that the total amount of hydrogen peroxide used in S3 accounts for 0.1% of the mass of secondary wastewater.

[0121] The CODcr of the tertiary wastewater was 211 mg / L, and its color was nearly colorless and transparent.

Claims

1. A method for treating DSD acid oxidation wastewater, characterized in that, Includes the following steps: S1. Wastewater extraction: First, extract the acid oxidation wastewater with an extractant to obtain primary wastewater and oil phase. Then, back extract the oil to obtain DNS concentrate. The DNS concentrate is recovered and used in the DNS reduction section to prepare DSD acid. S2. Macroporous resin adsorption: Primary wastewater is adsorbed through macroporous resin to obtain secondary wastewater, and then desorbed by desorbent to recover DNS. S3, Iron-Carbon Micro-Electrolysis: Iron and carbon are used to treat secondary wastewater through micro-electrolysis, and then inorganic adsorbents are used to treat the wastewater after micro-electrolysis to obtain tertiary wastewater; S4, MVR evaporation and concentration: MVR evaporation and concentration of tertiary wastewater to obtain high-quality salt, and the distilled water is used for S2 resin desorption or DSD preparation process. The extractant comprises organic amine extractants or ether extractants; the extractant also comprises alcohol extractants or phosphate extractants; the extractant further comprises other extractants, including at least one of toluene, gasoline, kerosene, sulfonated kerosene, and carbon tetrachloride; the volume ratio of organic amine extractants or ether extractants, alcohol extractants or phosphate extractants, and other extractants is 2-6:1-3:1-7; the ether extractant comprises at least one of diisopropyl ether, ethylhexyl ether, and 9-alkenyl-12-hydroxyoctadecanoic acid polyoxyethylene ether-10; the phosphate extractant comprises at least one of hexyl phosphate di(2-ethylhexyl) ester, dioctyl phosphate octyl ester, and tributyl phosphate; the alcohol extractant comprises at least one of isoamyl alcohol, sec-octyl alcohol, isooctyl alcohol, and n-octyl alcohol; the organic amine extractant is at least one of trioctyldecyl tertiary amine, quaternary ammonium salt, trioctylamine, and dodecyl tertiary amine; The macroporous resin is a macroporous weakly basic anion exchange resin, which includes at least one of styrene-based, phenolic-based, and acrylic-based resins; the adsorption temperature in S2 is 0-50℃, and the flow rate of wastewater through the macroporous resin is 0.25-5 BV / h. The extraction temperature in S1 is 20-50℃, and the extraction pH is 1-6; the back-extraction temperature is 20-60℃, and the back-extraction pH is 8-12. The desorbent used in S2 is water or dilute alkali, the flow rate of the desorbent is 0.5-6 BV / h, the amount of desorbent is 2-15 BV, and the desorption temperature is 60-100℃. The iron-carbon mixture is a mixture of iron and activated carbon, or an iron-carbon filler obtained by sintering iron, carbon and their metal catalysts; the mass ratio of iron to activated carbon in the iron-carbon mixture is 0.1-0.5:1-2; hydrogen peroxide is also introduced during the micro-electrolysis process, and the amount of hydrogen peroxide introduced accounts for 0.05-2% of the mass of the secondary wastewater.

2. The application of the processing method according to claim 1, characterized in that, The treatment method is used for the treatment of at least one type of wastewater, including DSD acid oxidation wastewater, sulfonation wastewater or reduction wastewater from DSD acid preparation.