An efficient treatment method for biodegradable plastic production wastewater

Abstract

This invention discloses a highly efficient method for treating wastewater from the production of biodegradable plastics, belonging to the field of wastewater treatment technology. The treatment process comprises the following steps: pretreatment → high-efficiency anaerobic treatment → high-efficiency aerobic treatment → secondary sedimentation → high-density sedimentation → meeting water standards. This process is simple to operate and does not cause secondary pollution to the environment. The treated wastewater has COD ≤ 500 mg / L, NH3-N ≤ 45 mg / L, TN ≤ 70 mg / L, and a pH of 6.5 to 9.5.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, in particular to a high-efficiency treatment method for biodegradable plastic production wastewater. Background Art

[0002] PHA is a natural polymer material that is internationally recognized as 100% biodegradable. PHA is produced through microbial fermentation. PHA production wastewater typically includes process wastewater (wastewater from starch hydrolysis and sugar processing, and mother liquor and wastewater from PHA fermentation, separation, and extraction), exhaust gas washing wastewater, cooling water, detergent, and flushing wastewater. Due to its excellent material properties, PHA is widely used in packaging, medical treatment, chemical industry, agriculture, functional materials, and other fields. PHA has excellent biodegradability, and its decomposition products are all bioavailable.

[0003] CN111453856A discloses a wastewater treatment agent and wastewater treatment process for efficient decolorization and COD degradation. These technologies relate to the field of wastewater treatment technology and aim to address the difficulty in degrading COD in wastewater. The technical solution comprises 20-30% of a water treatment agent, 50-60% of microbial capsule particles, 20-30% of honeycomb ceramic particles, and 1-5% of a flocculant. The wastewater treatment agent is added to high-COD industrial wastewater at a mass ratio of 1:0.010 to 1:0.025, stirred thoroughly, and the high-COD industrial wastewater is kept at a temperature of 20-35°C. The mixture is then allowed to stand for 1-5 hours.

[0004] CN104030421B discloses a composite wastewater COD remover and a method for removing COD from wastewater, belonging to the fields of industrial wastewater treatment and domestic sewage treatment. The composite COD remover of the present invention is produced by a polymerization reaction of ferrous sulfate, sodium chlorate, aluminum nitrate, aluminum sulfate, aluminum chloride, sodium sulfite, sodium nitrite, sodium metabisulfite, polyacrylamide, and deionized water in a certain proportion. The composite wastewater COD remover is added to high-COD industrial wastewater in a certain proportion, and an appropriate amount of alkali is added to adjust the pH value to 7-8. The mixture is stirred at room temperature for 3 minutes and allowed to stand for 10-15 minutes.

[0005] PHA fermentation wastewater has the following characteristics: high salt (1.9%), high COD, high NH3-N, and high total nitrogen. However, there are few existing public technologies for efficiently treating wastewater generated during the PHA production process. Summary of the Invention

[0006] In order to solve the above technical problems, the wastewater generated in the PHA production process is efficiently treated. The present invention provides a method for efficiently treating biodegradable plastic production wastewater, which belongs to the field of wastewater treatment technology.

[0007] An efficient method for treating wastewater from the production of biodegradable plastics comprises the following steps:

[0008] (1) Pretreatment: Wastewater enters the pretreatment section from the collection tank to remove water-insoluble impurities and adjust the pH of the wastewater;

[0009] (2) High-efficiency anaerobic: The pre-treated effluent is lifted and sent to high-efficiency anaerobic equipment to control pH value and water temperature, with a residence time of 3-5 days;

[0010] (3) High-efficiency aerobic: The effluent from the high-efficiency anaerobic equipment flows through the buffer tank and is then transferred to the high-efficiency aerobic reactor. The pH value and water temperature are controlled, and the residence time is 1-3 days.

[0011] (4) High-density sedimentation: The effluent is discharged by high-efficiency aerobic means and flows into the secondary sedimentation tank for separation of bacterial sludge and water. The effluent enters the high-density sedimentation tank and is treated by flocculation and dosing with PAC and synergists to remove suspended solids. The precipitated sludge is concentrated and the upper clear water flows into the clear water discharge tank.

[0012] The preferred technical solution is that the pH range in the pretreatment step is 8.5 to 9.0.

[0013] The preferred technical solution is that the pH range in the high-efficiency anaerobic process is 7.5 to 8.0.

[0014] The preferred technical solution is: the temperature in the high-efficiency anaerobic process is controlled at 30-35°C.

[0015] The preferred technical solution is that the pH range in the high-efficiency aerobic process is 7.0 to 8.0.

[0016] The preferred technical solution is: the temperature in the high-efficiency aerobic process is controlled at 30-35°C.

[0017] The preferred technical solution is: in the high-density precipitation process, PAC is added to the wastewater to control the overall concentration to be 3-4.5 mg / L.

[0018] The preferred technical solution is: in the high-density precipitation process, the synergist is added to the wastewater to control the overall concentration to be 0.2-0.5 mg / L.

[0019] The preferred technical solution is: the preparation method of the synergist is:

[0020] Acrylamide, 2-methylacrylate zinc, 3-(2-carboxyvinyl)phenylboric acid, sodium dodecylbenzenesulfonate, benzoyl peroxide and deionized water are mixed in a mass ratio of (1-2): (0.3-0.6): (0.05-0.09): (0.02-0.04): (8-11), ultrasonically dispersed for 0.5-2h, then nitrogen is introduced to heat the reaction, and water is removed by distillation under reduced pressure to obtain a synergist.

[0021] The preferred technical solution is: the reaction temperature is 45-60°C and the reaction time is 2-4h.

[0022] Compared with the prior art, the present invention has the following technical effects:

[0023] (1) The technical method adopted by the present invention for treating wastewater is simple to operate and will not cause secondary pollution to the environment.

[0024] (2) This method has a good wastewater treatment effect. The treated water quality is: COD≤500mg / L, NH3-N≤45mg / L, TN≤70mg / L, pH6.5~9.5.

[0025] (3) The copolymerization modification of acrylamide, zinc 2-methacrylate, 3-(2-carboxyvinyl)phenylboronic acid and sodium dodecylbenzenesulfonate yields a synergist that is rich in organic zinc and phenylboronic acid functional groups. It can react with NH3-N and amino compounds in the wastewater of biodegradable plastic production, which is conducive to rapid flocculation, increased density and increased precipitation efficiency. DETAILED DESCRIPTION

[0026] To make the above-mentioned objects, features, and advantages of the present invention more readily apparent, specific embodiments of the present invention are described in detail below. The following description sets forth numerous specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0027] Example 1:

[0028] An efficient method for treating wastewater from the production of biodegradable plastics, the specific process comprises the following steps:

[0029] (1) Pretreatment: The wastewater enters the pretreatment section from the collection tank to remove water-insoluble impurities in the wastewater and adjust the pH to 8.5;

[0030] (2) High-efficiency anaerobic: The pre-treated effluent is lifted and sent to the high-efficiency anaerobic equipment, with a pH control range of 7.5, a temperature control of 30°C, and a residence time of 3 days;

[0031] (3) High-efficiency aerobic: The effluent from the high-efficiency anaerobic equipment flows through the buffer tank and is then transferred to the high-efficiency aerobic reactor. The pH is controlled within 7.0, the temperature is controlled at 30°C, and the residence time is 1 day.

[0032] (4) High-density sedimentation: The effluent is discharged by high-efficiency aerobic means and flows into the secondary sedimentation tank for separation of bacterial sludge and water. The effluent enters the high-density sedimentation tank and is treated by flocculation and dosing with PAC (3 mg / L) and synergist (0.2 mg / L) to remove suspended solids. The precipitated sludge is concentrated and the upper clear water flows into the clear water discharge tank.

[0033] The preparation method of the synergist is:

[0034] Acrylamide, zinc 2-methacrylate, 3-(2-carboxyvinyl)phenylboric acid, sodium dodecylbenzenesulfonate, benzoyl peroxide and deionized water were mixed in a mass ratio of 1:0.3:0.05:0.02:8, and ultrasonic dispersion was performed for 0.5 h. Then nitrogen was introduced, the temperature was controlled to 60°C, the reaction was stirred for 2 h, and water was removed by distillation under reduced pressure to obtain a synergist.

[0035] Example 2

[0036] An efficient method for treating wastewater from the production of biodegradable plastics, the specific process comprises the following steps:

[0037] (1) Pretreatment: The wastewater enters the pretreatment section from the collection tank to remove water-insoluble impurities in the wastewater and adjust the pH to 8.5;

[0038] (2) High-efficiency anaerobic: The pre-treated effluent is lifted and sent to the high-efficiency anaerobic equipment, with a pH control range of 7.5, a temperature control of 30°C, and a residence time of 5 days;

[0039] (3) High-efficiency aerobic: The effluent from the high-efficiency anaerobic equipment flows through the buffer tank and is then transferred to the high-efficiency aerobic reactor. The pH is controlled within 7.0, the temperature is controlled at 35°C, and the residence time is 3 days.

[0040] (4) High-density sedimentation: The effluent is discharged by high-efficiency aerobic means and flows into the secondary sedimentation tank for separation of bacterial sludge and water. The effluent enters the high-density sedimentation tank and is treated by flocculation and dosing with PAC (4.5 mg / L) and synergist (0.3 mg / L) to remove suspended solids. The precipitated sludge is concentrated and the upper clear water flows into the clear water discharge tank.

[0041] The preparation method of the synergist is:

[0042] Acrylamide, zinc 2-methacrylate, 3-(2-carboxyvinyl)phenylboric acid, sodium dodecylbenzenesulfonate, benzoyl peroxide and deionized water were mixed in a mass ratio of 1:0.6:0.09:0.02:9, and ultrasonically dispersed for 1 hour. Then, nitrogen was introduced, the temperature was controlled to 55°C, and the reaction was stirred for 2 hours. Water was removed by distillation under reduced pressure to obtain a synergist.

[0043] Example 3

[0044] An efficient method for treating wastewater from the production of biodegradable plastics, the specific process comprises the following steps:

[0045] (1) Pretreatment: The wastewater enters the pretreatment section from the collection tank to remove water-insoluble impurities in the wastewater and adjust the pH to 9.0;

[0046] (2) High-efficiency anaerobic: The pre-treated effluent is lifted and sent to the high-efficiency anaerobic equipment, with a pH control range of 8.0, a temperature control of 35°C, and a residence time of 3 days;

[0047] (3) High-efficiency aerobic: The effluent from the high-efficiency anaerobic equipment flows through the buffer tank and is then transferred to the high-efficiency aerobic reactor. The pH is controlled within 7.0, the temperature is controlled at 30°C, and the residence time is 1 day.

[0048] (4) High-density sedimentation: The effluent is discharged by gravity into the secondary sedimentation tank for separation of bacterial sludge and water; the effluent enters the high-density sedimentation tank, where suspended solids are removed by flocculation and dosing with PAC (3 mg / L) and synergist (0.4 mg / L). The precipitated sludge is concentrated and the upper clear water flows into the clear water discharge tank.

[0049] The preparation method of the synergist is:

[0050] Acrylamide, zinc 2-methacrylate, 3-(2-carboxyvinyl)phenylboric acid, sodium dodecylbenzenesulfonate, benzoyl peroxide and deionized water were mixed in a mass ratio of 2:0.5:0.05:0.03:11, and ultrasonically dispersed for 1 hour. Then, nitrogen was introduced, the temperature was controlled to 50°C, and the reaction was stirred for 3 hours. Water was removed by distillation under reduced pressure to obtain a synergist.

[0051] Example 4

[0052] An efficient method for treating wastewater from the production of biodegradable plastics, the specific process comprises the following steps:

[0053] (1) Pretreatment: The wastewater enters the pretreatment section from the collection tank to remove water-insoluble impurities in the wastewater and adjust the pH to 9.0;

[0054] (2) High-efficiency anaerobic: The pre-treated effluent is lifted and sent to the high-efficiency anaerobic equipment, with a pH control range of 7.5, a temperature control of 35°C, and a residence time of 5 days;

[0055] (3) High-efficiency aerobic: The effluent from the high-efficiency anaerobic equipment flows through a buffer tank and is then transferred to a high-efficiency aerobic reactor. The pH is controlled within 8.0, the temperature is controlled at 35°C, and the residence time is 3 days.

[0056] (4) High-density sedimentation: The effluent is discharged by high-efficiency aerobic means and flows into the secondary sedimentation tank for separation of bacterial sludge and water. The effluent enters the high-density sedimentation tank and is treated by flocculation and dosing with PAC (4.5 mg / L) and synergist (0.5 mg / L) to remove suspended solids. The precipitated sludge is concentrated and the upper clear water flows into the clear water discharge tank.

[0057] The preparation method of the synergist is:

[0058] Acrylamide, zinc 2-methacrylate, 3-(2-carboxyvinyl)phenylboric acid, sodium dodecylbenzenesulfonate, benzoyl peroxide and deionized water were mixed in a mass ratio of 2:0.4:0.06:0.04:9, and ultrasonically dispersed for 2 hours. Then, nitrogen was introduced, the temperature was controlled to 45°C, the reaction was stirred for 4 hours, and water was removed by distillation under reduced pressure to obtain a synergist.

[0059] An efficient method for treating wastewater from the production of biodegradable plastics, the specific process comprises the following steps:

[0060] (1) Pretreatment: The wastewater enters the pretreatment section from the collection tank to remove water-insoluble impurities in the wastewater and adjust the pH to 8.5;

[0061] (2) High-efficiency anaerobic: The pre-treated effluent is lifted and sent to the high-efficiency anaerobic equipment, with a pH control range of 7.5, a temperature control of 30°C, and a residence time of 3 days;

[0062] (3) High-efficiency aerobic: The effluent from the high-efficiency anaerobic equipment flows through the buffer tank and is then transferred to the high-efficiency aerobic reactor. The pH is controlled within 7.0, the temperature is controlled at 30°C, and the residence time is 1 day.

[0063] (4) High-density sedimentation: The effluent is discharged by high-efficiency aerobic means and flows into the secondary sedimentation tank for separation of bacterial sludge and water. The effluent enters the high-density sedimentation tank and is treated by flocculation and dosing with PAC (3 mg / L) to remove suspended solids. The precipitated sludge is then concentrated and the upper layer of clear water flows into the clear water discharge tank.

[0064] Comparative Example 2

[0065] An efficient method for treating wastewater from the production of biodegradable plastics, the specific process comprises the following steps:

[0066] (1) Pretreatment: The wastewater enters the pretreatment section from the collection tank to remove water-insoluble impurities in the wastewater and adjust the pH to 8.5;

[0067] (2) High-efficiency anaerobic: The pre-treated effluent is lifted and sent to the high-efficiency anaerobic equipment, with a pH control range of 7.5, a temperature control of 30°C, and a residence time of 3 days;

[0068] (3) High-efficiency aerobic: The effluent from the high-efficiency anaerobic equipment flows through the buffer tank and is then transferred to the high-efficiency aerobic reactor. The pH is controlled within 7.0, the temperature is controlled at 30°C, and the residence time is 1 day.

[0069] (4) High-density sedimentation: The effluent is discharged by high-efficiency aerobic means and flows into the secondary sedimentation tank for separation of bacterial sludge and water. The effluent enters the high-density sedimentation tank and is treated by flocculation and dosing with PAC (3 mg / L) and synergist (0.2 mg / L) to remove suspended solids. The precipitated sludge is concentrated and the upper clear water flows into the clear water discharge tank.

[0070] The preparation method of the synergist is:

[0071] Acrylamide, 3-(2-carboxyvinyl)phenylboric acid, sodium dodecylbenzenesulfonate and deionized water were mixed in a mass ratio of 1:0.05:8, ultrasonically dispersed for 0.5 h, introduced nitrogen, controlled the temperature to 60° C., stirred for reaction for 2 h, and distilled under reduced pressure to remove water to obtain a synergist.

[0072] The above embodiment is compared with the comparative example:

[0073]

Claims

1. An efficient method for treating wastewater from the production of biodegradable plastics, comprising the following steps: (1) Pretreatment: Wastewater enters the pretreatment section from the collection tank to remove water-insoluble impurities and adjust the pH of the wastewater; (2) High-efficiency anaerobic: The pre-treated effluent is lifted and sent to high-efficiency anaerobic equipment to control pH value and water temperature, with a residence time of 3-5 days; (3) High-efficiency aerobic: The effluent from the high-efficiency anaerobic equipment flows through the buffer tank and is then transferred to the high-efficiency aerobic reactor. The pH value and water temperature are controlled, and the residence time is 1-3 days. (4) High-density sedimentation: The effluent from the high-efficiency aerobic treatment flows into the secondary sedimentation tank for separation of bacterial sludge and water; the effluent enters the high-density sedimentation tank, where suspended solids are removed through flocculation and dosing with PAC and synergists. The precipitated sludge is concentrated and the upper clear water flows into the clear water discharge tank; The preparation method of the synergist is: Acrylamide, 2-methylacrylate zinc, 3-(2-carboxyvinyl)phenylboric acid, sodium dodecylbenzenesulfonate, benzoyl peroxide and deionized water are mixed in a mass ratio of (1-2): (0.3-0.6): (0.05-0.09): (0.02-0.04): (8-11), ultrasonically dispersed for 0.5-2h, then nitrogen is introduced to heat the reaction, and water is removed by distillation under reduced pressure to obtain a synergist.

2. The method for efficiently treating wastewater from the production of biodegradable plastics according to claim 1, wherein: The pH range in the pretreatment step is 8.5 to 9.

0.

3. The method for efficiently treating wastewater from the production of biodegradable plastics according to claim 1, wherein: The pH range in the high-efficiency anaerobic process is 7.5 to 8.

0.

4. The method for efficiently treating wastewater from the production of biodegradable plastics according to claim 1, wherein: The temperature in the high-efficiency anaerobic process is controlled at 30-35°C.

5. The method for efficiently treating wastewater from the production of biodegradable plastics according to claim 1, wherein: The pH range in the high-efficiency aerobic process is 7.0 to 8.

0.

6. The method for efficiently treating wastewater from the production of biodegradable plastics according to claim 1, wherein: The temperature in the high-efficiency aerobic process is controlled at 30-35°C.

7. The method for efficiently treating wastewater from the production of biodegradable plastics according to claim 1, wherein: In the high-density precipitation process, PAC is added to the wastewater to control the overall concentration to be 3-4.5 mg / L.

8. The method for efficiently treating wastewater from the production of biodegradable plastics according to claim 1, wherein: In the high-density precipitation process, the synergist is added to the wastewater to control the overall concentration to be 0.2-0.5 mg / L.

9. The method for efficiently treating wastewater from the production of biodegradable plastics according to claim 1, wherein: The reaction temperature during the preparation of the synergist is 45-60° C., and the reaction time is 2-4 hours.

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