Treatment method for improving biodegradability of sorbic acid wastewater

Abstract

The invention discloses a treatment method for improving biodegradability of sorbic acid wastewater, and belongs to the technical field of chemical engineering. The method specifically comprises the following steps: filtering the wastewater containing sorbic acid, distilling at 100-102 DEG C to remove low-boiling-point organic matters such as ethanol in the wastewater, and distilling out a small amount of water at the same time; the method comprises the following steps: uniformly mixing aluminum silicate, an oxide and a binder according to a ratio of (5-10): 1: (5-8), carrying out suction filtration, carrying out vacuum drying, grinding to 50-100 meshes, carrying out roasting activation at a roasting temperature of 200-400 DEG C for 2-4 hours, cooling to normal temperature to obtain a recyclable solid catalyst, allowing wastewater to pass through a tubular reactor filled with the solid catalyst, standing for 4-10 hours, and keeping the temperature of the wastewater at 140-160 DEG C and the reaction pressure at 0.4-0.7 MPa; after the reaction, cooling and standing for layering, the content of the sorbic acid in the upper water layer is 0.008-0.030%, and the removal rate of the sorbic acid in the wastewater reaches 95-98%.

Description

Technical Field

[0001] The invention relates to a treatment method for improving the biodegradability of sorbic acid wastewater, belonging to the field of chemical industry. Background Art

[0002] Sorbic acid is an unsaturated fatty acid with conjugated double bonds. Like natural unsaturated acids, it participates in the human body's metabolic process and is oxidized into carbon dioxide and water. It is currently the preservative with the lowest metabolic toxicity in industrial production. Sorbic acid is an acidic preservative that has a significant inhibitory effect on molds, aerobic bacteria, and yeasts. It is easy to combine with thiol groups in microbial enzyme systems, thereby destroying many important enzyme systems to achieve the purpose of antibacterial and preservation.

[0003] Sorbic acid production wastewater has a large volume, complex composition, high organic matter concentration and poor biodegradability. At present, the domestic treatment of sorbic acid production wastewater mostly adopts a pretreatment-biological treatment combined process, which removes most of the organic matter and sorbic acid in the wastewater through treatment including neutralization, precipitation, flocculation, dilution, membrane separation and other technologies, and then carries out biochemical treatment.

[0004] Patent CN1168671C reports a method for treating and recycling washing wastewater in sorbic acid production. Resin is used to absorb sorbic acid in wastewater, reducing COD in wastewater and providing conditions for subsequent biochemical treatment. Patent CN114684956A reports a membrane separation method for recycling sorbic acid in sorbic acid wastewater. Ultrafiltration and nanofiltration devices are used to separate sorbic acid concentrate and clean water, and to achieve resource utilization. These technologies all extract and separate sorbic acid from wastewater and recycle it. To a certain extent, the operation is cumbersome and the cost is high; direct biochemical treatment has certain difficulties. This technology starts from the properties of sorbic acid and converts it into a non-water-soluble polymer in wastewater, avoiding the increase of other reagents and equipment and reducing the treatment cost. Summary of the invention

[0005] In the present invention, sorbic acid in wastewater is self-polymerized under the action of a catalyst and converted into a high polymer, thereby forming a layer with water, thereby effectively reducing the content of sorbic acid in the wastewater and reducing the pressure of the wastewater entering subsequent biochemical treatment.

[0006] The present invention provides a method for treating sorbic acid wastewater, the method comprising the following steps:

[0007] (1) filtering the sorbic acid wastewater to remove tar and other insoluble substances therein;

[0008] (2) distilling the filtered wastewater until the top temperature reaches 98-102° C. and then stopping the distillation;

[0009] (3) adding a solid catalyst to the wastewater treated in step (2), with a reaction time of 4 to 10 hours, a reaction temperature of 140 to 160° C., and a pressure condition of 0.4 to 0.7 MPa, wherein the solid catalyst is aluminum silicate and an oxide, and the oxide is one or more of titanium dioxide, silicon dioxide, and zirconium dioxide;

[0010] (4) After the reaction is completed, the pressure is released, the mixture is cooled, and the mixture is allowed to stand to obtain a wastewater treatment liquid from which sorbic acid has been removed.

[0011] In one embodiment, in step (1), the filtration is performed by using any adsorption method selected from porous activated carbon columns, resins, graphene, and electrosorption, and the tar and other insoluble substances are removed before filtration.

[0012] In one embodiment, in step (2), distillation is stopped until the top temperature reaches 102°C.

[0013] In one embodiment, in step (2), the sorbic acid content in the wastewater after distillation is 0.4-0.6%.

[0014] In one embodiment, the preparation method of the solid catalyst described in step (3) is to mix aluminum silicate, oxide and binder in a ratio of 4-11:0.5-1.5:4-9, filter, roast and activate, and the binder includes but is not limited to water; further, the ratio is 5-10:1:5-8.

[0015] In one embodiment, the oxide is selected from one or more of titanium dioxide, silicon dioxide, and zirconium dioxide.

[0016] In one embodiment, the binder is one or more of water, methanol, and methyltrimethoxysilane.

[0017] In one embodiment, the solid particles are ground and sieved to have a particle size of 50 to 100 meshes after filtering and then calcined and activated; further, the particle size is 50 meshes.

[0018] In one embodiment, the calcination activation is performed at a temperature of 200 to 400° C. for 2 to 4 hours; further, the calcination activation is performed at 400° C. for 4 hours.

[0019] In one embodiment, in step (3), the preparation method of the solid catalyst is to stir and mix aluminum silicate, oxide and binder in a mass ratio of 5:1:5, filter and grind to obtain solid particles with a particle size of 50 mesh, calcine the solid particles at 400°C for 2h, and cool to obtain the solid catalyst; the binder includes but is not limited to deionized water.

[0020] In one embodiment, the solid catalyst is reactivated after being used for 2 to 4 weeks.

[0021] In one embodiment, in step (3), after adding the solid catalyst to the wastewater treated in step (2), the reaction conditions are controlled to be a temperature of 140 to 160° C., a pressure of 0.4 to 0.7 MPa, and a reaction time of 4 to 10 h; further, the reaction conditions are controlled to be a temperature of 160° C., a pressure of 0.7 MPa, and a reaction time of 10 h.

[0022] In one embodiment, in step (3), a solid catalyst is added to the wastewater treated in step (2), and the solid catalyst is loaded into a shell-and-tube reactor after activation.

[0023] In one embodiment, the filling height of the solid catalyst is 80% of the length of the reaction tube of the shell-and-tube reactor.

[0024] In one embodiment, in step (4), the cooling is to cool the wastewater to 25°C via a heat exchanger.

[0025] In one embodiment, in step (4), after standing and stratification, the sorbic acid content in the upper aqueous layer is 0.008-0.030%.

[0026] In one embodiment, the method comprises the steps of:

[0027] (1) passing the sorbic acid wastewater through a carbon column to remove tar and other insoluble substances therein by adsorption and then filtering;

[0028] (2) distilling the filtered wastewater to remove most of the low-boiling point organic matter such as ethanol in the wastewater until the top temperature reaches 102° C. and stopping the distillation;

[0029] (3) Preparation and activation of solid catalyst: aluminum silicate and titanium dioxide are mixed with a binder, deionized water, in a ratio of 5-10:1:5-8, filtered, dried, ground, and calcined at high temperature for activation;

[0030] (4) continuously passing the wastewater treated in step (2) through the activated solid catalyst for a residence time of 4 to 10 hours, a reaction temperature of 140 to 160° C., and a reaction pressure of 0.4 to 0.7 MPa;

[0031] (5) After the reaction is completed, the liquid phase is cooled to 20-25°C through a heat exchanger, and the layers are allowed to stand for separation. The upper water layer is sent to a biochemical system for treatment, and the lower polymer layer is sent to incineration for treatment.

[0032] The invention also provides application of the treatment method in treating sorbic acid wastewater, and the removal rate of sorbic acid in the wastewater reaches 95-98%.

[0033] The invention effectively promotes the self-polymerization conversion of sorbic acid by controlling the amount of catalyst, reaction temperature, reaction pressure and reaction time during the reaction process, and separates the sorbic acid polymer from wastewater by liquid separation treatment, further reduces the content of sorbic acid in the wastewater, and improves the biochemical treatment capacity.

[0034] Beneficial Effects

[0035] (1) The method provided by the present invention mainly targets the chemical structure of sorbic acid. By controlling the polymerization conditions (solid catalyst prepared by aluminum silicate and titanium dioxide and binder deionized water in a ratio of 5-10:1:5-8, reaction temperature of 140-160° C., reaction time of 4-10 h and reaction pressure of 0.4-0.7 MPa), it is converted into a polymer under certain conditions, thereby separating from the water layer, achieving the effect of removing sorbic acid, reducing the content of sorbic acid in wastewater, and thereby improving the biodegradability of wastewater;

[0036] (2) The sorbic acid content in the wastewater treated by the present invention is only 0.008-0.030%, and the removal rate of sorbic acid can reach 95-98%. DETAILED DESCRIPTION

[0037] The following is a specific implementation method of improving the biodegradability of sorbic acid wastewater provided by the present invention.

[0038] 1. The sorbic acid wastewater involved in the following embodiments is production wastewater, with an initial COD of 180,000 to 200,000 mg / L and an ethanol content of 3.5 to 4%. After treatment by the present invention, the COD is 90,000 to 120,000 mg / L and the ethanol content is 0.5 to 0.8%.

[0039] 2. The detection method / calculation formula involved in the following embodiments:

[0040] Sorbic acid content was determined by high performance liquid chromatography

[0041] Instruments and equipment: Liquid chromatograph;

[0042] Chromatographic column: Agilent Eclipse XDB-C18;

[0043] Test steps: Weigh about 0.15g of sample, add solvent to ultrasonically dissolve, dilute with water to a 100mL volumetric flask, filter through a 0.45μm filter membrane and inject. Turn on the chromatograph, wait for all operating conditions of the instrument to stabilize, inject the sample solution into the injection valve with a micro-syringe, wait for all components to flow out, and process the results with a chromatographic workstation or integrator.

[0044] The calculation formula of sorbic acid removal rate is:

[0045]

[0046] Example 1: Treatment method for improving the biodegradability of sorbic acid wastewater

[0047] (1) Sorbic acid wastewater is adsorbed by a porous activated carbon column to remove tar and other insoluble substances, and then filtered by filter paper;

[0048] (2) The supernatant of the filtered wastewater is distilled through a distillation tower until the top temperature reaches 102° C., and the distillation is stopped to separate and remove most of the low-boiling point organic matter (including about 3% ethanol). After measurement, the sorbic acid content in the wastewater after distillation is 0.60%;

[0049] (3) Preparation and activation of solid catalyst:

[0050] Aluminum silicate, titanium dioxide nanopowder and binder (deionized water) were stirred and mixed in a mass ratio of 5:1:5, filtered through a Buchner funnel, ground and sieved into solid particles with a particle size of 50 mesh, and the solid particles were calcined at 400°C for 2h to complete activation and cooled to room temperature;

[0051] (4) adding the wastewater treated in step (2) to a shell-and-tube reactor filled with the activated solid catalyst prepared in step (3) (the solid catalyst filling height is 80% of the length of the reaction tube of the shell-and-tube reactor), controlling the temperature in the shell-and-tube reactor to 140° C., the pressure to 0.4 MPa, and the wastewater retention time to 10 h;

[0052] (5) After the reaction is completed, the pressure is released, and the wastewater is cooled to 25° C. through a heat exchanger and allowed to stand for stratification and separation. The sorbic acid content in the water layer is measured to be 0.018%. The sorbic acid removal rate is finally 97.0% based on the residual sorbic acid content in the wastewater.

[0053] Example 2: Treatment method for improving the biodegradability of sorbic acid wastewater

[0054] Referring to Example 1, the only difference is that the polymerization reaction temperature is adjusted to 160° C. and the pressure is 0.7 MPa. The specific steps are as follows:

[0055] (1) Sorbic acid wastewater is adsorbed by a porous activated carbon column to remove tar and other insoluble substances, and then filtered by filter paper;

[0056] (2) The filtered wastewater supernatant is distilled through a distillation tower until the top temperature reaches 102° C., and the distillation is stopped to separate and remove most of the low-boiling point organic matter (including about 3% ethanol). After measurement, the sorbic acid content in the wastewater after distillation is 0.59%;

[0057] (3) Preparation and activation of solid catalyst:

[0058] Aluminum silicate, titanium dioxide nanopowder and binder (deionized water) were stirred and mixed in a mass ratio of 5:1:5, filtered through a Buchner funnel, ground and sieved into solid particles with a particle size of 50 mesh, and the solid particles were calcined at 400°C for 2h and cooled to room temperature to obtain;

[0059] (4) adding the wastewater treated in step (2) to a shell-and-tube reactor filled with the activated solid catalyst prepared in step (3) (the solid catalyst filling height is 80% of the length of the reaction tube of the shell-and-tube reactor), controlling the temperature in the shell-and-tube reactor to 160° C., the pressure to 0.7 MPa, and the wastewater retention time to 10 h;

[0060] (5) After the reaction is completed, the pressure is released, and the wastewater is cooled to 25° C. through a heat exchanger and allowed to stand for stratification and liquid separation. The sorbic acid content in the water layer is measured to be 0.010%. The sorbic acid removal rate is finally calculated to be 98.3% based on the residual sorbic acid content in the wastewater.

[0061] Example 3: Treatment method for improving the biodegradability of sorbic acid wastewater

[0062] Referring to Example 1, the only difference is that the polymerization reaction time is adjusted to 6 hours, and the specific steps are as follows:

[0063] (1) Sorbic acid wastewater is adsorbed by a porous activated carbon column to remove tar and other insoluble substances, and then filtered by filter paper;

[0064] (2) The filtered wastewater supernatant is distilled through a distillation tower until the top temperature reaches 102° C., and the distillation is stopped to separate and remove most of the low-boiling point organic matter (including about 3% ethanol). After measurement, the sorbic acid content in the wastewater after distillation is 0.59%;

[0065] (3) Preparation and activation of solid catalyst:

[0066] Aluminum silicate, titanium dioxide nanopowder and binder (deionized water) were stirred and mixed in a mass ratio of 5:1:5, filtered through a Buchner funnel, ground and sieved into solid particles with a particle size of 50 mesh, and the solid particles were calcined at 400°C for 2h and cooled to room temperature to obtain;

[0067] (4) adding the wastewater treated in step (2) to a shell-and-tube reactor filled with the activated solid catalyst prepared in step (3) (the solid catalyst filling height is 80% of the length of the reaction tube of the shell-and-tube reactor), controlling the temperature in the shell-and-tube reactor to 140° C., the pressure to 0.4 MPa, and the wastewater retention time to 6 h;

[0068] (5) After the reaction is completed, the pressure is released, and the wastewater is cooled to 25° C. through a heat exchanger and allowed to stand for stratification and liquid separation. The sorbic acid content in the water layer is measured to be 0.025%. The sorbic acid removal rate is finally calculated to be 95.8% based on the residual sorbic acid content in the wastewater.

[0069] Example 4: Treatment method for improving the biodegradability of sorbic acid wastewater

[0070] Referring to Example 1, the only difference is that the catalyst activation condition is adjusted to calcination at 400° C. for 4 h. The specific steps are as follows:

[0071] (1) Sorbic acid wastewater is adsorbed by a porous activated carbon column to remove tar and other insoluble substances, and then filtered by filter paper;

[0072] (2) The filtered wastewater supernatant is distilled through a distillation tower until the top temperature reaches 102° C., and the distillation is stopped to separate and remove most of the low-boiling point organic matter (including about 3% ethanol). After measurement, the sorbic acid content in the wastewater after distillation is 0.55%;

[0073] (3) Preparation and activation of solid catalyst:

[0074] Aluminum silicate, titanium dioxide nanopowder and binder (deionized water) were stirred and mixed in a mass ratio of 5:1:5, filtered through a Buchner funnel, ground and sieved into solid particles with a particle size of 50 mesh, and the solid particles were calcined at 400°C for 4h and cooled to room temperature to obtain;

[0075] (4) adding the wastewater treated in step (2) to a shell-and-tube reactor filled with the activated solid catalyst prepared in step (3) (the solid catalyst filling height is 80% of the length of the reaction tube of the shell-and-tube reactor), controlling the temperature in the shell-and-tube reactor to 140° C., the pressure to 0.4 MPa, and the wastewater retention time to 10 h;

[0076] (5) After the reaction is completed, the pressure is released, and the wastewater is cooled to 25° C. through a heat exchanger and allowed to stand for stratification and liquid separation. The sorbic acid content in the water layer is measured to be 0.022%. The sorbic acid removal rate is finally calculated to be 96.0% based on the residual sorbic acid content in the wastewater.

[0077] Example 5: Treatment method for improving the biodegradability of sorbic acid wastewater

[0078] Referring to Example 1, the only difference is that the catalyst preparation conditions are adjusted. The specific steps are as follows:

[0079] (1) Sorbic acid wastewater is adsorbed by a porous activated carbon column to remove tar and other insoluble substances, and then filtered by filter paper;

[0080] (2) The supernatant of the filtered wastewater is distilled through a distillation tower until the top temperature reaches 102° C., and the distillation is stopped to separate and remove most of the low-boiling point organic matter (including about 3% ethanol). After measurement, the sorbic acid content in the wastewater after distillation is 0.56%;

[0081] (3) Preparation and activation of solid catalyst:

[0082] Aluminum silicate, titanium dioxide nanopowder and binder (deionized water) were stirred and mixed in a mass ratio of 10:1:8, filtered through a Buchner funnel, ground and sieved into solid particles with a particle size of 50 mesh, and the solid particles were calcined at 400°C for 2h and cooled to room temperature to obtain;

[0083] (4) adding the wastewater treated in step (2) to a shell-and-tube reactor filled with the activated solid catalyst prepared in step (3) (the solid catalyst filling height is 80% of the length of the reaction tube of the shell-and-tube reactor), controlling the temperature in the shell-and-tube reactor to 140° C., the pressure to 0.4 MPa, and the wastewater retention time to 10 h;

[0084] (5) After the reaction is completed, the pressure is released, and the wastewater is cooled to 25° C. through a heat exchanger and allowed to stand for stratification and liquid separation. The sorbic acid content in the water layer is measured to be 0.028%. The sorbic acid removal rate is finally calculated to be 95.0% based on the residual sorbic acid content in the wastewater.

[0085] Example 6: Treatment method for improving the biodegradability of sorbic acid wastewater

[0086] Referring to Example 1, the only difference is that the titanium dioxide in Example 1 is adjusted to zirconium dioxide, and the specific steps are as follows:

[0087] (1) Sorbic acid wastewater is adsorbed by a porous activated carbon column to remove tar and other insoluble substances, and then filtered by filter paper;

[0088] (2) The filtered wastewater supernatant is distilled through a distillation tower until the top temperature reaches 102° C., and the distillation is stopped to separate and remove most of the low-boiling point organic matter (including about 3% ethanol). After measurement, the sorbic acid content in the wastewater after distillation is 0.55%;

[0089] (3) Preparation and activation of solid catalyst:

[0090] Aluminum silicate, zirconium dioxide nanopowder and binder (deionized water) were stirred and mixed in a mass ratio of 5:1:5, filtered through a Buchner funnel, ground and sieved into solid particles with a particle size of 50 mesh, and the solid particles were calcined at 400°C for 2h and cooled to room temperature to obtain;

[0091] (4) adding the wastewater treated in step (2) to a shell-and-tube reactor filled with the activated solid catalyst prepared in step (3) (the solid catalyst filling height is 80% of the length of the reaction tube of the shell-and-tube reactor), controlling the temperature in the shell-and-tube reactor to 140° C., the pressure to 0.4 MPa, and the wastewater retention time to 10 h;

[0092] (5) After the reaction is completed, the pressure is released, and the wastewater is cooled to 25° C. through a heat exchanger and allowed to stand for stratification and liquid separation. The sorbic acid content in the water layer is measured to be 0.018%. The sorbic acid removal rate is finally calculated to be 96.7% based on the residual sorbic acid content in the wastewater.

[0093] Example 7: Treatment method for improving the biodegradability of sorbic acid wastewater

[0094] Referring to Example 1, the only difference is that the titanium dioxide in Example 1 is adjusted to silicon dioxide, and the specific steps are as follows:

[0095] (1) Sorbic acid wastewater is adsorbed by a porous activated carbon column to remove tar and other insoluble substances, and then filtered by filter paper;

[0096] (2) The supernatant of the filtered wastewater is distilled through a distillation tower until the top temperature reaches 102° C., and the distillation is stopped to separate and remove most of the low-boiling point organic matter (including about 3% ethanol). After measurement, the sorbic acid content in the wastewater after distillation is 0.56%;

[0097] (3) Preparation and activation of solid catalyst:

[0098] Aluminum silicate, zirconium dioxide nanopowder and binder (deionized water) were stirred and mixed in a mass ratio of 5:1:5, filtered through a Buchner funnel, ground and sieved into solid particles with a particle size of 50 mesh, and the solid particles were calcined at 400°C for 2h and cooled to room temperature to obtain;

[0099] (4) adding the wastewater treated in step (2) to a shell-and-tube reactor filled with the activated solid catalyst prepared in step (3) (the solid catalyst filling height is 80% of the length of the reaction tube of the shell-and-tube reactor), controlling the temperature in the shell-and-tube reactor to 140° C., the pressure to 0.4 MPa, and the wastewater retention time to 10 h;

[0100] (5) After the reaction is completed, the pressure is released, and the wastewater is cooled to 25° C. through a heat exchanger and allowed to stand for stratification and liquid separation. The sorbic acid content in the water layer is measured to be 0.018%. The sorbic acid removal rate is finally calculated to be 96.9% based on the residual sorbic acid content in the wastewater.

[0101] Comparative Example 1: Treatment method for improving the biodegradability of sorbic acid wastewater

[0102] Referring to Example 1, the only difference is that the polymerization reaction temperature is adjusted to 100° C. and the pressure is adjusted to 0.3 MPa. The specific steps are as follows:

[0103] (1) Sorbic acid wastewater is adsorbed by a porous activated carbon column to remove tar and other insoluble substances, and then filtered by filter paper;

[0104] (2) The filtered wastewater supernatant is distilled through a distillation tower until the top temperature reaches 102° C., and the distillation is stopped to separate and remove most of the low-boiling point organic matter (including about 3% ethanol). After measurement, the sorbic acid content in the wastewater after distillation is 0.55%;

[0105] (3) Preparation and activation of solid catalyst:

[0106] Aluminum silicate, titanium dioxide nanopowder and binder (deionized water) were stirred and mixed in a mass ratio of 5:1:5, filtered through a Buchner funnel, ground and sieved into solid particles with a particle size of 50 mesh, and the solid particles were calcined at 400°C for 2h and cooled to room temperature to obtain;

[0107] (4) adding the wastewater treated in step (2) to a shell-and-tube reactor filled with the activated solid catalyst prepared in step (3) (the solid catalyst filling height is 80% of the length of the reaction tube of the shell-and-tube reactor), controlling the temperature in the shell-and-tube reactor to 100° C., the pressure to 0.3 MPa, and the wastewater retention time to 10 h;

[0108] (5) After the reaction is completed, the pressure is released, and the wastewater is cooled to 25° C. through a heat exchanger and allowed to stand for stratification and separation. The sorbic acid content in the water layer is measured to be 0.46%. The sorbic acid removal rate is finally calculated to be 16.4% based on the residual sorbic acid content in the wastewater.

[0109] Comparative Example 2: Treatment method for improving the biodegradability of sorbic acid wastewater

[0110] Referring to Example 1, the only difference is that the polymerization reaction time is adjusted to 2 hours. The specific steps are as follows:

[0111] (1) Sorbic acid wastewater is adsorbed by a porous activated carbon column to remove tar and other insoluble substances, and then filtered by filter paper;

[0112] (2) The supernatant of the filtered wastewater is distilled through a distillation tower until the top temperature reaches 102° C., and the distillation is stopped to separate and remove most of the low-boiling point organic matter (including about 3% ethanol). After measurement, the sorbic acid content in the wastewater after distillation is 0.50%;

[0113] (3) Preparation and activation of solid catalyst:

[0114] Aluminum silicate, titanium dioxide nanopowder and binder (deionized water) were stirred and mixed in a mass ratio of 5:1:5, filtered through a Buchner funnel, ground and sieved into solid particles with a particle size of 50 mesh, and the solid particles were calcined at 400°C for 2h and cooled to room temperature to obtain;

[0115] (4) adding the wastewater treated in step (2) to a shell-and-tube reactor filled with the activated solid catalyst prepared in step (3) (the solid catalyst filling height is 80% of the length of the reaction tube of the shell-and-tube reactor), controlling the temperature in the shell-and-tube reactor to 140° C., the pressure to 0.4 MPa, and the wastewater retention time to 2 h;

[0116] (5) After the reaction is completed, the pressure is released, and the wastewater is cooled to 25° C. through a heat exchanger and allowed to stand for stratification and liquid separation. The sorbic acid content in the water layer is measured to be 0.28%. The sorbic acid removal rate is finally calculated to be 44.0% based on the residual sorbic acid content in the wastewater.

[0117] Comparative Example 3: Treatment method for improving the biodegradability of sorbic acid wastewater

[0118] Referring to Example 1, the only difference is that the titanium dioxide in Example 1 is adjusted to zinc oxide, and the specific steps are as follows:

[0119] (1) Sorbic acid wastewater is adsorbed by a porous activated carbon column to remove tar and other insoluble substances, and then filtered by filter paper;

[0120] (2) The supernatant of the filtered wastewater is distilled through a distillation tower until the top temperature reaches 102° C., and the distillation is stopped to separate and remove most of the low-boiling point organic matter (including about 3% ethanol). After measurement, the sorbic acid content in the wastewater after distillation is 0.58%;

[0121] (3) Preparation and activation of solid catalyst:

[0122] Aluminum silicate, zinc oxide and a binder (deionized water) were stirred and mixed in a mass ratio of 5:1:5, filtered through a Buchner funnel, ground and sieved into solid particles with a particle size of 50 mesh, and the solid particles were roasted at 400°C for 2h and cooled to room temperature to obtain;

[0123] (4) adding the wastewater treated in step (2) to a shell-and-tube reactor filled with the activated solid catalyst prepared in step (3) (the solid catalyst filling height is 80% of the length of the reaction tube of the shell-and-tube reactor), controlling the temperature in the shell-and-tube reactor to 140° C., the pressure to 0.4 MPa, and the wastewater retention time to 10 h;

[0124] (5) After the reaction is completed, the pressure is released, and the wastewater is cooled to 25° C. through a heat exchanger and allowed to stand for stratification and liquid separation. The sorbic acid content in the water layer is measured to be 0.154%. The sorbic acid removal rate is finally calculated to be 73.4% based on the residual sorbic acid content in the wastewater.

[0125] Comparative Example 4: Treatment method for improving the biodegradability of sorbic acid wastewater

[0126] Referring to Example 1, the only difference is that the aluminum silicate in Example 1 is adjusted to magnesium silicate, and the specific steps are as follows:

[0127] (1) Sorbic acid wastewater is adsorbed by a porous activated carbon column to remove tar and other insoluble substances, and then filtered by filter paper;

[0128] (2) The supernatant of the filtered wastewater is distilled through a distillation tower until the top temperature reaches 102° C., and the distillation is stopped to separate and remove most of the low-boiling point organic matter (including about 3% ethanol). After measurement, the sorbic acid content in the wastewater after distillation is 0.58%;

[0129] (3) Preparation and activation of solid catalyst:

[0130] The magnesium silicate, zirconium dioxide nanopowder and binder (deionized water) were stirred and mixed in a mass ratio of 5:1:5, filtered through a Buchner funnel, ground and sieved into solid particles with a particle size of 50 mesh, and the solid particles were calcined at 400°C for 2h and cooled to room temperature to obtain;

[0131] (4) adding the wastewater treated in step (2) to a shell-and-tube reactor filled with the activated solid catalyst prepared in step (3) (the solid catalyst filling height is 80% of the length of the reaction tube of the shell-and-tube reactor), controlling the temperature in the shell-and-tube reactor to 140° C., the pressure to 0.4 MPa, and the wastewater retention time to 10 h;

[0132] (5) After the reaction is completed, the pressure is released, and the wastewater is cooled to 25° C. through a heat exchanger and allowed to stand for stratification and liquid separation. The sorbic acid content in the water layer is measured to be 0.219%. The sorbic acid removal rate is finally calculated to be 62.3% based on the residual sorbic acid content in the wastewater.

[0133] Comparative Example 5: Treatment method for improving the biodegradability of sorbic acid wastewater

[0134] Referring to Example 1, the difference is that the aluminum silicate in Example 1 is omitted and only titanium dioxide is used. The specific steps are as follows:

[0135] (1) Sorbic acid wastewater is adsorbed by a porous activated carbon column to remove tar and other insoluble substances, and then filtered by filter paper;

[0136] (2) The supernatant of the filtered wastewater is distilled through a distillation tower until the top temperature reaches 102° C., and the distillation is stopped to separate and remove most of the low-boiling point organic matter (including about 3% ethanol). After measurement, the sorbic acid content in the wastewater after distillation is 0.56%;

[0137] (3) Preparation and activation of solid catalyst:

[0138] The zirconium dioxide nanopowder and the binder (deionized water) were stirred and mixed in a mass ratio of 1:5, filtered through a Buchner funnel, ground and sieved into solid particles with a particle size of 50 mesh, and the solid particles were calcined at 400°C for 2h and cooled to room temperature to obtain;

[0139] (4) adding the wastewater treated in step (2) to a shell-and-tube reactor filled with the activated solid catalyst prepared in step (3) (the solid catalyst filling height is 80% of the length of the reaction tube of the shell-and-tube reactor), controlling the temperature in the shell-and-tube reactor to 140° C., the pressure to 0.4 MPa, and the wastewater retention time to 10 h;

[0140] (5) After the reaction is completed, the pressure is released, and the wastewater is cooled to 25° C. through a heat exchanger and allowed to stand for stratification and liquid separation. The sorbic acid content in the water layer is measured to be 0.242%. The sorbic acid removal rate is finally calculated to be 56.7% based on the residual sorbic acid content in the wastewater.

[0141] Comparative Example 6: Treatment method for improving the biodegradability of sorbic acid wastewater

[0142] Referring to Example 1, the difference is that the titanium dioxide in Example 1 is omitted and only aluminum silicate is used. The specific steps are as follows:

[0143] (1) Sorbic acid wastewater is adsorbed by a porous activated carbon column to remove tar and other insoluble substances, and then filtered by filter paper;

[0144] (2) The supernatant of the filtered wastewater is distilled through a distillation tower until the top temperature reaches 102° C., and the distillation is stopped to separate and remove most of the low-boiling point organic matter (including about 3% ethanol). After measurement, the sorbic acid content in the wastewater after distillation is 0.56%;

[0145] (3) Preparation and activation of solid catalyst:

[0146] Aluminum silicate and a binder (deionized water) are stirred and mixed in a mass ratio of 1:1, filtered through a Buchner funnel, ground and sieved into solid particles with a particle size of 50 mesh, and the solid particles are roasted at 400°C for 2h and cooled to room temperature to obtain;

[0147] (4) adding the wastewater treated in step (2) to a shell-and-tube reactor filled with the activated solid catalyst prepared in step (3) (the solid catalyst filling height is 80% of the length of the reaction tube of the shell-and-tube reactor), controlling the temperature in the shell-and-tube reactor to 140° C., the pressure to 0.4 MPa, and the wastewater retention time to 10 h;

[0148] (5) After the reaction is completed, the pressure is released, and the wastewater is cooled to 25° C. through a heat exchanger and allowed to stand for stratification and liquid separation. The sorbic acid content in the water layer is measured to be 0.267%. The sorbic acid removal rate is finally calculated to be 52.4% based on the residual sorbic acid content in the wastewater.

[0149] The method provided by the present invention mainly targets the chemical structure of sorbic acid, and by controlling polymerization conditions (catalyst, reaction temperature, time and pressure), converts it into a high polymer under certain conditions, thereby separating it from the water layer, achieving the effect of removing sorbic acid, reducing the content of sorbic acid in wastewater, and thus improving the biodegradability of wastewater.

[0150] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the definition of the claims.

Claims

1. A method for treating sorbic acid wastewater, characterized in that: The method comprises the following steps: (1) filtering the sorbic acid wastewater to remove tar and other insoluble substances therein; (2) distilling the filtered wastewater until the top temperature reaches 100-102°C and then stopping the distillation; (3) adding a solid catalyst to the wastewater treated in step (2), with a reaction time of 4 to 10 hours, a reaction temperature of 140 to 160° C., and a pressure condition of 0.4 to 0.7 MPa, wherein the solid catalyst is aluminum silicate and an oxide, and the oxide is one or more of titanium dioxide, silicon dioxide, and zirconium dioxide; (4) After the reaction is completed, the pressure is released, the mixture is cooled, and the mixture is allowed to stand to obtain a wastewater treatment liquid from which sorbic acid has been removed.

2. The processing method according to claim 1, characterized in that: The solid catalyst in step (3) is prepared by mixing aluminum silicate, oxide and binder in a ratio of 5-10:1:5-8, filtering, calcining and activating the mixture, wherein the binder includes but is not limited to water.

3. The processing method according to claim 2, characterized in that: The filtering is followed by grinding and screening to obtain solid particles with a particle size of 50 to 100 meshes, and then calcining and activating.

4. The processing method according to claim 3, characterized in that: The filtering step is followed by grinding and screening to obtain solid particles with a particle size of 50 meshes, and then calcining and activating the particles.

5. The processing method according to claim 4, characterized in that: The calcination activation is performed at a temperature of 200 to 400° C. for 2 to 4 hours.

6. The processing method according to claim 5, characterized in that: The calcination activation is performed at 400° C. for 4 hours.

7. The processing method according to claim 1, characterized in that: The filtration in step (1) is that the sorbic acid wastewater is adsorbed by a porous activated carbon column to remove tar and other insoluble substances therein and then filtered with filter paper.

8. The processing method according to claim 1, characterized in that: In step (3), after adding the solid catalyst to the wastewater treated in step (2), the reaction conditions are controlled to be temperature 160° C., pressure 0.7 MPa, and reaction time 10 h.

9. The processing method according to claim 1, characterized in that: In step (3), the preparation method of the solid catalyst is to stir and mix aluminum silicate, oxide and binder in a mass ratio of 5:1:5, filter and grind to form solid particles with a particle size of 50 mesh, calcine the solid particles at 400°C for 2h, and cool to obtain the solid catalyst; the binder includes but is not limited to deionized water.

10. Use of the treatment method according to any one of claims 1 to 9 in treating sorbic acid wastewater, wherein the removal rate of sorbic acid in the wastewater reaches 95 to 98%.

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