A treatment method for the production wastewater of 5-acetylacetamido benzimidazolone

Abstract

The invention discloses a treatment method for the production wastewater of 5-acetylacetamido benzimidazolone, mainly solving the technical problems of high investment and operation costs of enterprises producing wastewater of 5-acetylacetamido benzimidazolone, secondary pollution generation and unstable effluent indexes. The wastewater of the invention is successively passed through a high-concentration wastewater AO process, an oxidation process, an activated sludge AO process and a denitrification process, and most of the pollutants in the wastewater are degraded through a biochemical section, realizing the up-to-standard discharge of the wastewater at low cost.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater, and particularly to a method for treating wastewater produced in the production of 5-acetylacetoacetamido benzimidazolone. Background Art

[0002] As an organic chemical raw material, 5-acetylacetoacetamido benzimidazolone is widely used in the fields of medicine, pesticides, pigments and special material synthesis, especially in the application of high-grade pigments. The wastewater produced in the production of 5-acetylacetoacetamido benzimidazolone not only contains 5-acetylacetoacetamido benzimidazolone and 5-nitrobenzimidazolone, but also contains various imidazolone intermediate products such as 5-aminoimidazolone and benzimidazolone, urea, nitric acid and other substances. The wastewater has a complex composition and poor biodegradability.

[0003] During the production process of 5-acetylacetoacetamido benzimidazolone, multiple process sections are involved, and corresponding wastewater is produced in each process section, mainly including condensation mother liquor, acetylation mother liquor, acetylation washing water, decolorization pressure filtration washing water, nitrification mother liquor and nitrification washing water. The characteristics of single-strand wastewater are different. For example, the condensation mother liquor is alkaline, NH4+-N with a high pH value, while the nitrification mother liquor is acidic, with high TN value and TDS value. Therefore, different processes are required for treatment. However, for multi-process disposal, multiple sets of process equipment and multiple operators are required, and a large site is required, resulting in high overall investment and operating costs for enterprises.

[0004] At present, there are few reports on the treatment processes for this type of wastewater at home and abroad, mainly including activated carbon adsorption process, evaporation + biochemical process, mother liquor recycling by evaporation + physical and chemical + biochemical, micro-electrolysis + biochemical and other processes. The process investment and operating costs are all very high, and it is easy to produce secondary pollution and difficult to meet the discharge standards.

[0005] In the journal literature "Study on the Treatment of 5-Acetylacetoacetamido Benzimidazolone Wastewater by Micro-Electrolysis / Composite Microorganism Enhanced A / O Biochemical Method", when the influent COD is 6874 mg / L through the micro-electrolysis + composite microorganism enhanced AO process, the effluent COD < 500 mg / L. Although the COD has a good removal effect, most of the organic nitrogen in the wastewater cannot be converted into inorganic nitrogen through this process and finally removed through the nitrification and denitrification processes, and the TN cannot meet the discharge standards. Moreover, a large amount of iron mud is generated during the micro-electrolysis process, resulting in secondary pollution.

[0006] Therefore, it is necessary to develop a clean, efficient and economical wastewater treatment process, which can not only effectively remove COD and TN in the wastewater and meet the discharge standards, but also reduce the investment and operating costs of enterprises. Summary of the Invention

[0007] The object of the present invention is to provide a treatment method for the production wastewater of 5-acetylacetoacetamido benzimidazolone, which can solve the technical problems of high investment and operation costs of enterprises producing 5-acetylacetoacetamido benzimidazolone wastewater, secondary pollution generation and unstable effluent indexes.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] A treatment method for the production wastewater of 5-acetylacetoacetamido benzimidazolone, characterized by comprising the following steps:

[0010] Step 1, mix the production wastewater at each stage, namely the condensation mother liquor, acetylation mother liquor, acetylation washing water, decolorization pressure filtration washing water, nitration mother liquor and nitration washing water, and the obtained mixed wastewater has the following indexes:

[0011] COD 9000 - 12000 mg / L, TN 300 - 500 mg / L, NH4+-N 30-50 mg / L , NO3--N 200-300 mg / L , TP 3 - 5mg / L, TDS 10000 - 12000 mg / L, pH 2 - 4;

[0012] Adjust the pH of the mixed wastewater to 7 - 8 with NaOH, and filter after coagulation and precipitation;

[0013] Step 2, pass the filtered wastewater into the high-concentration wastewater AO treatment unit. The residence time of the wastewater in the high-concentration wastewater A process section is 24 - 36h, and the operating temperature is 20 - 30°C; the residence time of the wastewater in the high-concentration wastewater O process section is 12 - 18h, the operating temperature is 20 - 30°C, and the dissolved oxygen is 2 - 4mg / L;

[0014] Step 3, pass the wastewater treated by the high-concentration wastewater AO treatment unit into the oxidation treatment unit, and adopt catalytic ozone oxidation. The ozone dosage per liter of wastewater is 1 - 2g, and the wastewater residence time is 15 - 60min;

[0015] Step 4, pass the wastewater treated by the oxidation unit into the activated sludge AO treatment unit. The residence time of the wastewater in the activated sludge A section is 10 - 20h, and the operating temperature is 20 - 30°C; the residence time of the wastewater in the activated sludge O section is 6 - 12h, the operating temperature is 20 - 30°C, and the dissolved oxygen is 2 - 4mg / L. Use NaHCO3 to adjust the pH of the activated sludge O section to 7 - 8;

[0016] Step 5, pass the wastewater treated by the activated sludge AO treatment unit into the denitrification unit, and additionally add an electron donor. The operating temperature is 20 - 30°C, the dissolved oxygen is 0 - 0.5mg / L, and the wastewater residence time is 4 - 8h.

[0017] Further, the mixed wastewater in Step 1 is obtained by mixing six types of production wastewater, namely condensation mother liquor, acetylation mother liquor, acetylation washing water, decolorization pressure filtration washing water, nitrification mother liquor, and nitrification washing water, in a ratio of 12:165:45:15:0.6:16.

[0018] Further, the denitrification unit in Step 5 is one of an autotrophic denitrification filter or a heterotrophic denitrification filter. The electron donor used in the heterotrophic denitrification filter is one or any combination of two or more of methanol, sodium acetate, and glucose, and the electron donor used in the autotrophic denitrification filter is pyrite particles.

[0019] The present invention treats the production wastewater in each stage in a mixed manner, which can reduce the requirements for process equipment, operators, and sites, thereby reducing the overall investment and operating costs of the enterprise. In addition, for the mixed wastewater, the present invention first significantly reduces the COD and TN in the wastewater through the high-concentration wastewater AO treatment process, then converts the organic amines that are difficult to biotransform into organic amines that are easy to biotransform and removes part of the COD and color through the oxidation process, and then converts the organic amines into NH4+-N and finally converts into NO3--N , and finally through the denitrification filter, NO3--N is converted N2 , and finally reaches the standard for discharge. The process is mainly based on biological treatment and supplemented by oxidation process modification. Compared with the existing treatment processes, the treatment cost is significantly reduced, no secondary pollution is generated, and the effluent index is stable. Description of the Drawings

[0020] Figure 1 It shows the changes in the COD indexes of each process section in Examples 1 to 3.

[0021] Figure 2 It shows the changes in the N indexes of each process section in Example 1.

[0022] Figure 3 It shows the changes in the N indexes of each process section in Example 2.

[0023] Figure 4 It shows the changes in the N indexes of each process section in Example 3. Detailed Embodiments

[0024] The present invention will be described below through specific examples, but the present invention is not limited thereto. The experimental methods described in the following examples are all conventional methods unless otherwise specified; the reagents and materials described are all commercially available unless otherwise specified. The following examples are not intended to limit the patent scope of the present invention, and all equivalent implementations or changes made without departing from the present invention should be included in the scope of protection of this patent.

[0025] Table 1 Indexes of Each Share of Production Wastewater

[0026]

[0027] Table 2 Indexes of the mixed wastewater after mixing each stream of production wastewater in proportion

[0028]

[0029] Example 1

[0030] Mix each stream of production wastewater in proportion. The indexes of each stream of production wastewater before mixing are shown in Table 1, and the indexes of the mixed wastewater after mixing are shown in Table 2. After adjusting the pH of the mixed wastewater to 7 - 8 with 40% NaOH solution, carry out coagulation precipitation and filtration. Activate the high - concentration wastewater AO treatment unit, and add 0.5‰ (V / V) compound bacterial agent (mixed by volume percentage, and the bacterial density of each type of bacteria before mixing is 108CFU / mL , 30% Achromobacter sp. ATCC 43552, 20% Acinetobacter baumannii ATCC 19606, 30% Bacillus subtilis ATCC 6633, 10% Chryseobacterium gleum ATCC 35910, 10% Delftia acidovorans ATCC 15668; among them, Achromobacter sp. ATCC 43552 and Bacillus subtilis ATCC 6633 are cultured by expanding with commercially available TSB medium, Acinetobacter baumannii ATCC 19606, Chryseobacterium gleum ATCC 35910, and Delftia acidovorans ATCC 15668 are cultured by expanding with nutrient broth agar medium. The formula of the nutrient broth agar medium: 3 g of beef extract, 5 g of NaCl, 10 g of peptone, 20 g of agar, 1000 ml of distilled water, pH 7.4 - 7.6; the compound bacterial agents used in Examples 2 and 3 are the same as those in Example 1), add 50% (V / V) of the filtered wastewater and 50% (V / V) of the nutrient solution to the A process section of the high - concentration wastewater, and add 20% (V / V) of the filtered wastewater and 80% (V / V) of the nutrient solution to the O process section of the high - concentration wastewater (the formula of the nutrient solution: 2 g of glucose, 1 g of amino acid, KH2PO4 0.6g 、 K2HPO4 0.4g 、 MgSO4 0.2g, 0.2 g of NaCl, 0.35 g of NaOH, 1 L of tap water). Among them, the high-concentration wastewater A process section is filled with granular activated carbon with a particle size of 1-6 mesh, and the filling amount of granular activated carbon is 30% (V / V) of the pool volume. The high-concentration wastewater O process section is filled with polyurethane sponge fillers. The polyurethane sponge fillers (special biological fillers for RAS of Shandong Banghao Environmental Protection Technology Co., Ltd., with a shape specification of 22 ± 1 mm, an expansion coefficient of 1.2 after water absorption, and calculated according to the volume after water absorption expansion during filling) have a filling amount of 10% (V / V) of the pool volume (note that the above-mentioned volume percentages of the bacterial agent, granular activated carbon, and polyurethane sponge fillers added / filled are based on the pool volume; the volume percentages of the wastewater and nutrient solution added are based on the remaining pool volume after adding the composite bacterial agent and filling the fillers. The same applies to Examples 2 and 3).

[0031] The high-concentration wastewater A process section is statically activated for one week at an operating temperature of 30 °C, and then filtered wastewater is started to be introduced. The operating temperature is 30 °C, and the wastewater retention time is 30 h. After the high-concentration wastewater O process section is aerobically activated for one week at an operating temperature of 30 °C and a dissolved oxygen of 2 mg / L, the effluent from the high-concentration wastewater A process section is started to be introduced. The operating temperature is 30 °C, the wastewater retention time is 18 h, and the dissolved oxygen is 4 mg / L. The effluent from the high-concentration wastewater AO treatment unit is introduced into the catalytic ozone oxidation treatment unit. The catalyst used is the aluminum-based ozone catalyst of Shandong Longantai Environmental Protection Technology Co., Ltd. The dosage of the aluminum-based ozone catalyst is 80% (V / V) of the pool volume, and the ozone dosage per liter of the effluent from the high-concentration wastewater AO treatment unit is 2 g, and the wastewater retention time is 30 min. The effluent from the oxidation treatment unit is introduced into the activated sludge A process section. Calculated according to the pool volume, 40 g of sludge with a water content of 80% (municipal sludge, the same below) is added per liter of volume. The operating temperature is 30 °C, and the wastewater retention time is 18 h. The effluent from the activated sludge A process section is introduced into the activated sludge O process section. Calculated according to the pool volume, 20 g of sludge with a water content of 80% is added per liter of volume. The operating temperature is 30 °C, the wastewater retention time is 12 h, and the dissolved oxygen is 4 mg / L. During the operation, NaHCO3 the pH is adjusted to 7.5. The effluent from the activated sludge AO treatment unit enters the heterotrophic denitrifying biological filter. Glucose monohydrate is used as the organic electron donor, and the dosage is 6 times the total amount of the effluent from the AO treatment unit NO3--N , and the wastewater retention time is 8 h. The COD indexes of each process section are as Figure 1 shown, and the N indexes are as Figure 2 shown.

[0032] Example 2

[0033] Mix various production wastewaters in proportion, adjust the pH to 7 - 8 with 40% NaOH solution, and then conduct coagulation precipitation and filtration. Activate the high - concentration wastewater AO treatment unit, and add 0.5‰ (V / V) compound bacterial agent to each of the high - concentration wastewater AO treatment units. Add 50% (V / V) filtered wastewater and 50% (V / V) nutrient solution to the A process section of the high - concentration wastewater. Add 20% (V / V) filtered wastewater and 80% (V / V) nutrient solution to the O process section of the high - concentration wastewater (nutrient solution formula: 2 g of glucose, 1 g of amino acid, KH2PO4 0.6g , K2HPO4 0.4g , MgSO4 0.2g , NaCl 0.2 g, NaOH 0.35 g, 1 L of tap water). Among them, the A process section of the high - concentration wastewater is filled with 1 - 6 mesh granular activated carbon, and the filling amount of the granular activated carbon is 30% (V / V) of the pool volume. The O process section of the high - concentration wastewater is filled with polyurethane sponge filler. The polyurethane sponge filler (the special biological filler for RAS of Shandong Banghao Environmental Protection Technology Co., Ltd., with a shape specification of 22 ± 1 mm and a swelling coefficient of 1.2 after water absorption, and calculated according to the volume after water absorption and swelling during filling) has a filling amount of 10% (V / V) of the pool volume.

[0034] The A process section of the high - concentration wastewater is statically activated at a running temperature of 30°C for one week, and then filtered wastewater is introduced. The running temperature is 30°C, and the wastewater residence time is 30 h. After the O process section of the high - concentration wastewater is aerobically activated at a running temperature of 30°C and a dissolved oxygen of 2 mg / L for one week, the effluent from the A process section of the high - concentration wastewater is introduced. The running temperature is 30°C, the wastewater residence time is 18 h, and the dissolved oxygen is 4 mg / L. The effluent from the high - concentration wastewater AO treatment unit is adjusted to pH 3 with H2SO4 and then introduced into the Fendon oxidation treatment unit. Add 1 mL of 30% hydrogen peroxide to each liter of the effluent from the high - concentration wastewater AO treatment unit, FeSO4.7H2O 0.25g , the reaction time is 2 h. After the reaction, adjust the pH to 9 with 40% NaOH, and conduct coagulation precipitation and filtration. The effluent from the oxidation treatment unit is introduced into the activated sludge A process section. Calculated according to the pool volume, add 40 g of sludge with 80% water content per liter of volume. The running temperature is 30°C, and the wastewater residence time is 18 h. The effluent from the activated sludge A process section is introduced into the activated sludge O process section. Calculated according to the pool volume, add 20 g of sludge with 80% water content per liter of volume. The running temperature is 30°C, the wastewater residence time is 12 h, and the dissolved oxygen is 4 mg / L. During the operation, adjust the pH to 7.5 with NaHCO3 . The effluent from the activated sludge AO treatment unit enters the heterotrophic denitrification biological filter, and uses monohydrate glucose as the organic electron donor, with a dosage of 6 times the effluent volume of the AO treatment unit. The wastewater residence time is 8 h. The COD indexes of each process section are as shown in NO3--N , and the N indexes are as shown in Figure 1 , and the N indexes are as shown in Figure 3 .

[0035] Example 3

[0036] Mix the wastewater from each stream in proportion, adjust the pH to 7-8 with 40% NaOH solution, and then coagulate, precipitate and filter. Activate the high-concentration wastewater AO treatment unit, add 0.5‰ (V / V) compound bacterial agent to each high-concentration wastewater AO treatment unit, add 50% (V / V) filtered wastewater and 50% (V / V) nutrient solution to the high-concentration wastewater A process section, and add 20% (V / V) filtered wastewater and 80% (V / V) nutrient solution to the high-concentration wastewater O process section (nutrient solution formula: 2g glucose, 1g amino acid, KH2PO4 0.6g , K2HPO4 0.4g , MgSO4 0.2g , NaCl0.2g, NaOH 0.35g, tap water 1L). The high-concentration wastewater A process section was statically activated at an operating temperature of 30°C for one week, and filtered wastewater was introduced. The operating temperature was 30°C, and the wastewater retention time was 30h. The high-concentration wastewater O process section was aerated activated at an operating temperature of 30°C and dissolved oxygen 2mg / L for one week, and then the effluent from the high-concentration wastewater A process section was introduced. The operating temperature was 30°C, the wastewater retention time was 18h, and the dissolved oxygen was 4mg / L. The effluent from the high-concentration wastewater AO treatment unit was introduced into the electrocatalytic oxidation treatment unit. The electrocatalytic anode was made of titanium and loaded with palladium, ruthenium, and iridium precious metals. The cathode was made of titanium. The current density 5mA / cm2 The effluent from the oxidation treatment unit is fed into the activated sludge process section A, with 40g of 80% sludge added per liter, the operating temperature is 30°C, and the wastewater retention time is 18h; the effluent from the activated sludge process section A is fed into the activated sludge process section O, and according to the tank capacity, 20g of 80% sludge is added per liter, the operating temperature is 30°C, the wastewater retention time is 12h, and the dissolved oxygen is 4mg / L. NaHCO3 The pH was adjusted to 7.5. The effluent from the activated sludge AO treatment unit entered the heterotrophic denitrification biofilter, using monohydrate glucose as an organic electron donor at a dosage of 7.5. NO3--N The wastewater retention time is 8h. The COD index of each process section is as follows: Figure 1 As shown, the N index is Figure 4 shown.

[0037] Conclusion: Combining Figures 1-4It can be seen that when the oxidation unit process is the ozone catalytic oxidation process, the process has the best effect on the removal of COD in the effluent of the high-concentration wastewater AO treatment unit and the modification effect of hardly biodegradable organic amines, and the overall process effluent effect is also the best, with COD being 144 mg / L and TN being 45.3 mg / L. When the oxidation unit process is the Fenton process or the electrocatalytic oxidation process, the process has a poor effect on the removal of COD in the effluent of the high-concentration wastewater AO treatment unit and the modification effect of hardly biodegradable organic amines, resulting in the overall process effluent effect being inferior to that of the overall process when the oxidation unit process is the ozone catalytic oxidation process. When the oxidation unit process is the Fenton process, the overall process effluent COD is 456 mg / L and TN is 86.3 mg / L. When the oxidation unit process is the electrocatalytic oxidation process, the overall process effluent COD is 547 mg / L and TN is 95.2 mg / L.

Claims

1. A method for treating the production wastewater of 5-acetylacetamido benzimidazolone, characterized in that, It includes the following steps: Step 1: Mix the production wastewater at each stage, namely condensation mother liquor, acetylation mother liquor, acetylation washing water, decolorization pressure filtration washing water, nitration mother liquor and nitration washing water. The indexes of the mixed wastewater are as follows. COD 9000 - 12000 mg / L, TN 300 - 500 mg / L, NH4 + -N 30 - 50 mg / L, NO3 - -N 200 - 300 mg / L, TP 3 - 5 mg / L, TDS 10000 - 12000 mg / L, pH is 2 - 4; Adjust the pH of the mixed wastewater to 7 - 8 with NaOH, followed by coagulation precipitation and then filtration. Step 2: The filtered wastewater is fed into the high-concentration wastewater AO treatment unit. The wastewater retention time in the A process section of the high-concentration wastewater is 24 - 36 h, and the operating temperature is 20 - 30 °C. The wastewater retention time in the O process section of the high-concentration wastewater is 12 - 18 h, the operating temperature is 20 - 30 °C, and the dissolved oxygen is 2 - 4 mg / L. Step 3: The wastewater treated by the high-concentration wastewater AO treatment unit is fed into the oxidation treatment unit, and catalytic ozone oxidation is adopted. The ozone dosage per liter of wastewater is 1 - 2 g, and the wastewater retention time is 15 - 60 min. Step 4: The wastewater treated by the oxidation unit is fed into the activated sludge AO treatment unit. The wastewater retention time in the A section of the activated sludge is 10 - 20 h, and the operating temperature is 20 - 30 °C. The wastewater retention time in the O section of the activated sludge is 6 - 12 h, the operating temperature is 20 - 30 °C, and the dissolved oxygen is 2 - 4 mg / L. Adjust the pH of the O section of the activated sludge to 7 - 8 with NaHCO3. Step 5: The wastewater treated by the activated sludge AO treatment unit is fed into the denitrification unit, and an additional electron donor is added. The operating temperature is 20 - 30 °C, the dissolved oxygen is 0 - 0.5 mg / L, and the wastewater retention time is 4 - 8 h. In Step 2, 0.5‰ (V / V) of the composite bacterial agent was added to each of the high-concentration wastewater AO treatment units and mixed by volume percentage. The bacterial density of each type of bacteria before mixing was 10 8 CFU / mL, 30% Achromobacter sp. ATCC 43552, 20% Acinetobacter baumannii ATCC 19606, 30% Bacillus subtilis ATCC 6633, 10% Chryseobacterium gleum ATCC 35910, and 10% Delftia acidovorans ATCC 15668.

2. The treatment method of 5-acetoacetylaminobenzimidazolone production wastewater according to claim 1, characterized in that, In Step 2, the A process section of the high-concentration wastewater adopts the treatment form of 1 - 6 mesh granular activated carbon and composite bacteria biofilm method, and the filling amount of the granular activated carbon is 30% (V / V) of the pool volume. The O process section of the high-concentration wastewater adopts the treatment form of polyurethane sponge filler and composite bacteria biofilm method, and the filling amount of the polyurethane sponge filler is 10% (V / V) of the pool volume.

3. A method for treating the production wastewater of 5-acetylacetoacetamido benzimidazolone according to claim 1, characterized in that The denitrification unit described in Step 5 is one of an autotrophic denitrification filter or a heterotrophic denitrification filter. The electron donor used in the heterotrophic denitrification filter is one of methanol, sodium acetate, glucose or any combination of two or more of them, and the electron donor used in the autotrophic denitrification filter is pyrite particles.

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