Method for recycling p-hydroxybenzoic acid from p-hydroxybenzoic acid production water

Abstract

The invention discloses a method for recycling p-hydroxybenzoic acid from p-hydroxybenzoic acid production water, which comprises the following steps of: stirring and mixing an adsorbent and a flocculating agent in an aeration tank by pushing the production water through the aeration tank, so that the contact area of the adsorbent and the flocculating agent with the production water can be increased; according to the method, the adsorption agent and the flocculating agent are alternately added, so that the removal efficiency of organic matters, high salt and strong alkali in the production water is accelerated, and the removal of the organic matters, high salt and strong alkali in the production water reaches the standard in a manner of alternately adding the adsorption agent and the flocculating agent, so that the influence of impurities and harmful substances in the production water on the subsequent recovery rate of p-hydroxybenzoic acid is reduced; the pretreated production water is conveyed by adopting a plurality of conveying pipes, and the p-hydroxybenzoic acid in the production water is synchronously absorbed by macroporous adsorption resin at multiple positions, so that the adsorption rate of the p-hydroxybenzoic acid can be improved, and the recovery speed and efficiency of the p-hydroxybenzoic acid in the p-hydroxybenzoic acid production water are improved.

Description

Technical Field

[0001] The invention relates to the technical field of production wastewater recovery and treatment, in particular to a method for recovering p-hydroxybenzoic acid from p-hydroxybenzoic acid production water. Background Art

[0002] Parahydroxybenzoic acid and its esters are mainly used for the preservation of food, medicine and cosmetics. They can inhibit the growth of mold and are used in foods such as soy sauce, jam, and refreshing drinks. At present, parahydroxybenzoic acid will produce wastewater during the production process. In order to avoid the waste of parahydroxybenzoic acid, the parahydroxybenzoic acid in the parahydroxybenzoic acid production water will be recovered.

[0003] At present, it is very important to treat harmful substances such as high concentration of organic matter, high salt content, strong alkali, etc. in the water produced by para-hydroxybenzoic acid. In the process of recovering para-hydroxybenzoic acid, the treatment of the above harmful substances takes a long time and is difficult to remove. Incomplete treatment will affect the recovery rate of para-hydroxybenzoic acid in the water produced by para-hydroxybenzoic acid. Therefore, a method for recovering para-hydroxybenzoic acid from water produced by para-hydroxybenzoic acid production is proposed to solve this problem. Summary of the invention

[0004] To achieve the above object, the present invention provides the following technical solution: a method for recovering p-hydroxybenzoic acid from p-hydroxybenzoic acid production water, comprising the following steps: Step 1: introduce the para-hydroxybenzoic acid production water into the aeration tank, put the adsorbent into the aeration tank, and perform aeration mixing; the adsorbent adsorbs high-concentration organic matter, high salt content, strong alkali and other substances in the para-hydroxybenzoic acid production water; by adding flocculants, floccules are formed in the production water, and the floccules are salvaged to achieve pretreatment of the production water; Step 2: Detect the organic matter, high salt content and strong alkali content in p-hydroxybenzoic acid by high performance liquid chromatography (HPLC), conductivity measurement and pH meter, and proceed to the next step after the test meets the standard; Step 3: Introduce the pretreated production water into the adsorption tank. The adsorption tank adopts a double-layer design. The upper layer is filled with macroporous adsorption resin, and a filter is set between the lower and upper layers. The filter is covered with macroporous adsorption resin; When the pre-treated water is introduced into the adsorption tank, it is transported by multiple pipes, and the spacing between the bottom ends of the multiple transport pipes is not less than 50 cm; thus, the macroporous adsorption resin is formed to adsorb the p-hydroxybenzoic acid component in the production water over a large area at multiple positions; Step 4: desorbing and regenerating the adsorption saturated adsorption resin using hot alkali solution, then washing with clean water to recover p-hydroxybenzoic acid and its intermediates; Step 5: Biochemically treat the effluent after desorption to ensure that the treated water quality meets the discharge standards or reuse requirements.

[0005] Preferably, in step 1, the adsorbent is in powder form, and the adsorbent is one or more of silica gel, alumina, activated carbon, polyacrylamide, zeolite molecular sieve and carbon molecular sieve.

[0006] Preferably, in step 1, aeration and adsorbent are applied to produced water simultaneously, and aeration is configured to promote large-area contact between adsorbent and produced water.

[0007] Preferably, in step 1, after the flocculant is added, aeration is not stopped, and aeration is used to promote sufficient mixing of the flocculant and suspended particles in the production water. After the flocculant is added, aeration is stopped and allowed to stand for 10-20 minutes, and the flocculant is configured to flocculate the suspended particles and adsorbent in the production water.

[0008] Preferably, in step 2, after the salvageable part that does not meet the standard is detected and flocculated, the input amount of the adsorbent and the flocculant is increased until the detection meets the standard; Among the impurities of p-hydroxybenzoic acid: The organic matter content must be ≤1.0%; High salt content: sulfate content is ≤1%; Strong alkaline content: pH value is 6.5-9.5.

[0009] Preferably, in step 3, the macroporous adsorption resin is one or more of NDA-101 resin, 717 resin, NDA-88 resin, CHA-101 resin, D201 resin and D301R resin.

[0010] Compared with the prior art, the present invention has the following beneficial effects: The present invention adopts adsorbent and flocculant in the aeration tank, and utilizes the aeration tank to push the produced water to form stirring and mixing, which can accelerate the contact area between the adsorbent and flocculant and the produced water, thereby accelerating the removal efficiency of organic matter, high salt and strong alkali in the produced water, and by alternating the adsorbent and flocculant input, the removal of organic matter, high salt and strong alkali in the produced water can be achieved, thereby reducing the influence of impurities and harmful substances in the produced water on the subsequent recovery rate of p-hydroxybenzoic acid; and by adopting multiple delivery pipes to transport the pretreated produced water, the macroporous adsorption resin is used to synchronously absorb the p-hydroxybenzoic acid in the produced water at multiple positions, which can increase the adsorption rate of p-hydroxybenzoic acid, so as to improve the recovery speed and efficiency of p-hydroxybenzoic acid in the p-hydroxybenzoic acid production water. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a schematic diagram of the process of the present invention; Figure 2 It is a schematic diagram of multiple delivery pipes of the present invention. DETAILED DESCRIPTION

[0012] The present invention will be described in more detail below by way of examples, which are merely illustrative and do not in any way limit the scope of the present invention.

[0013] The present invention provides a technical solution: a method for recovering p-hydroxybenzoic acid from p-hydroxybenzoic acid production water, comprising the following steps: Step 1: introduce the para-hydroxybenzoic acid production water into the aeration tank, put the adsorbent into the aeration tank, and perform aeration mixing; the adsorbent adsorbs high-concentration organic matter, high salt content, strong alkali and other substances in the para-hydroxybenzoic acid production water; by adding flocculants, floccules are formed in the production water, and the floccules are salvaged to achieve pretreatment of the production water; Step 2: Detect the organic matter, high salt content and strong alkali content in p-hydroxybenzoic acid by high performance liquid chromatography (HPLC), conductivity measurement and pH meter, and proceed to the next step after the test meets the standard; Step 3: Introduce the pretreated production water into the adsorption tank. The adsorption tank adopts a double-layer design. The upper layer is filled with macroporous adsorption resin, and a filter is set between the lower and upper layers. The filter is covered with macroporous adsorption resin; When the pre-treated water is introduced into the adsorption tank, it is transported by multiple pipes, and the spacing between the bottom ends of the multiple transport pipes is not less than 50 cm; thus, the macroporous adsorption resin is formed to adsorb the p-hydroxybenzoic acid component in the production water over a large area at multiple positions; Step 4: Desorb and regenerate the saturated adsorption resin using hot alkali solution, then rinse with clean water to recover p-hydroxybenzoic acid and its intermediates; Step 5: Biochemically treat the effluent after desorption to ensure that the treated water quality meets the discharge standards or reuse requirements.

[0014] Embodiment 1: The p-hydroxybenzoic acid production water is introduced into the aeration tank, and the adsorbent is put into the aeration tank for aeration and mixing; the adsorbent adsorbs the high-concentration organic matter, high salt content, strong alkali and other substances in the p-hydroxybenzoic acid production water; flocculants are added to form flocs in the production water, and the flocs are salvaged to achieve pretreatment of the production water; the organic matter, high salt content and strong alkali content in p-hydroxybenzoic acid are tested by high performance liquid chromatography (HPLC), conductivity measurement and pH meter, and the next step is entered after the test meets the standard; the pretreated production water is introduced into the adsorption tank, and the adsorption tank adopts Double-layer design, with macroporous adsorption resin filling the upper layer, and a filter screen arranged between the lower and upper layers, and the filter screen is covered with macroporous adsorption resin; when the pre-treated water is introduced into the adsorption tank, it is transported by multiple pipes, and the spacing at the bottom of the multiple transport pipes is not less than 50cm; the macroporous adsorption resin is formed to adsorb the p-hydroxybenzoic acid component in the production water in a large area at multiple positions; the adsorption saturated adsorption resin is desorbed and regenerated with hot alkaline solution, and then rinsed with clean water to recover p-hydroxybenzoic acid and its intermediates; the effluent after desorption is biochemically treated; ensure that the treated water quality meets the discharge standards or reuse requirements.

[0015] Embodiment 2: In the first embodiment, the following steps are added: In step 1, the adsorbent is in powder form, and the adsorbent is one or more of silica gel, alumina, activated carbon, polyacrylamide, zeolite molecular sieve and carbon molecular sieve; aeration and adsorbent are carried out on the produced water simultaneously, and aeration is configured to promote large-area contact between the adsorbent and the produced water; after the flocculant is added, the aeration does not stop, and the aeration promotes the full mixing of the flocculant and the suspended particles in the produced water. After the flocculant is added, the aeration is stopped for 10-20 minutes and then allowed to stand, and the flocculant is configured to flocculate the suspended particles in the produced water and the adsorbent.

[0016] The production water of para-hydroxybenzoic acid is introduced into the aeration tank, and the adsorbent is put into the aeration tank for aeration and mixing; the adsorbent adsorbs high-concentration organic matter, high salt content, strong alkali and other substances in the production water of para-hydroxybenzoic acid; flocculants are formed in the production water by adding flocculants, and the flocculants are salvaged to achieve pretreatment of the production water; the adsorbent is powdery, and the adsorbent is one or more of silica gel, alumina, activated carbon, polyacrylamide, zeolite molecular sieve and carbon molecular sieve; aeration and adsorbent are carried out on the production water simultaneously, and aeration is configured to promote large-area contact between the adsorbent and the production water; after the flocculant is put in, the aeration does not stop, and the aeration promotes the full mixing of the flocculant and the suspended particles in the production water, and after the flocculant is put in, the aeration is stopped for 10-20 minutes and then left to stand, and the flocculant is configured to flocculate the suspended particles and the adsorbent in the production water; The organic matter, high salt content and strong alkali content in the p-hydroxybenzoic acid are detected by high performance liquid chromatography (HPLC), conductivity measurement and pH meter, and the next step is entered after the test meets the standard; the pretreated production water is introduced into the adsorption tank, the adsorption tank adopts a double-layer design, the upper layer is filled with macroporous adsorption resin, and a filter is set between the lower and upper layers, and the filter is covered with macroporous adsorption resin; when the pretreated water is introduced into the adsorption tank, multi-tube transportation is adopted, and the spacing at the bottom of the multi-transport pipe is set not less than 50cm; the macroporous adsorption resin is formed to adsorb the p-hydroxybenzoic acid component in the production water in multiple positions; the adsorption saturated adsorption resin is desorbed and regenerated with hot alkali solution, and then rinsed with clean water to recover p-hydroxybenzoic acid and its intermediates; the effluent after desorption is biochemically treated; ensure that the treated water quality meets the discharge standard or reuse requirements.

[0017] Embodiment three: In the second embodiment, the following steps are added: In step 2, after the salvageable part that does not meet the standard is detected and flocculated, the input amount of adsorbent and flocculant is increased until the detection meets the standard; Among the impurities of p-hydroxybenzoic acid: The organic matter content must be ≤1.0%; High salt content: sulfate content is ≤1%; Strong alkaline content: pH value is 6.5-9.5.

[0018] The production water of para-hydroxybenzoic acid is introduced into the aeration tank, and the adsorbent is put into the aeration tank for aeration and mixing; the adsorbent adsorbs high-concentration organic matter, high salt content, strong alkali and other substances in the production water of para-hydroxybenzoic acid; flocculants are formed in the production water by adding flocculants, and the flocculants are salvaged to achieve pretreatment of the production water; the adsorbent is powdery, and the adsorbent is one or more of silica gel, alumina, activated carbon, polyacrylamide, zeolite molecular sieve and carbon molecular sieve; aeration and adsorbent are carried out on the production water simultaneously, and aeration is configured to promote large-area contact between the adsorbent and the production water; after the flocculant is put in, the aeration does not stop, and the aeration promotes the full mixing of the flocculant and the suspended particles in the production water. After the flocculant is put in, the aeration is stopped for 10-20 minutes and then left to stand. The flocculant is configured to flocculate the suspended particles and the adsorbent in the production water; the organic matter, high salt content and strong alkali content in para-hydroxybenzoic acid are detected by high performance liquid chromatography (HPLC), conductivity measurement and pH meter. Detection, and proceed to the next step after the detection meets the standard; after the detection does not meet the standard, the part that can be salvaged is flocculated, and the input amount of adsorbent and flocculant is increased until the detection meets the standard; among the impurities of p-hydroxybenzoic acid: organic matter content: must be ≤1.0%; high salt content: sulfate content is ≤1%; strong alkali content: pH value is 6.5-9.5; the pretreated production water is introduced into the adsorption tank, the adsorption tank adopts a double-layer design, the upper layer is filled with macroporous adsorption resin, and a filter is set between the lower and upper layers, and the macroporous adsorption resin is covered with the filter; when the pretreated water is introduced into the adsorption tank, multi-tube transportation is adopted, and the spacing at the bottom of the multi-transportation pipe is set not less than 50cm; a large-area adsorption of p-hydroxybenzoic acid components in the production water by macroporous adsorption resin at multiple positions is formed; the adsorption saturated adsorption resin is desorbed and regenerated with hot alkali solution, and then rinsed with clean water to recover p-hydroxybenzoic acid and its intermediates; the desorbed water is biochemically treated; ensure that the treated water quality meets the discharge standard or reuse requirements.

[0019] Embodiment 4: In the third embodiment, the following steps are added: In step 3, the macroporous adsorption resin is one or more of NDA-101 resin, 717 resin, NDA-88 resin, CHA-101 resin, D201 resin and D301R resin.

[0020] The production water of para-hydroxybenzoic acid is introduced into the aeration tank, and the adsorbent is put into the aeration tank for aeration and mixing; the adsorbent adsorbs high-concentration organic matter, high salt content, strong alkali and other substances in the production water of para-hydroxybenzoic acid; flocculants are formed in the production water by adding flocculants, and the flocculants are salvaged to achieve pretreatment of the production water; the adsorbent is powdery, and the adsorbent is one or more of silica gel, alumina, activated carbon, polyacrylamide, zeolite molecular sieve and carbon molecular sieve; aeration and adsorbent are carried out on the production water simultaneously, and aeration is configured to promote large-area contact between the adsorbent and the production water; after the flocculant is put in, the aeration does not stop, and the aeration promotes the full mixing of the flocculant and the suspended particles in the production water. After the flocculant is put in, the aeration is stopped for 10-20 minutes and then left to stand. The flocculant is configured to flocculate the suspended particles and the adsorbent in the production water; by high performance liquid chromatography (HPLC), conductivity measurement and pH The organic matter, high salt content and strong alkali content in p-hydroxybenzoic acid are tested, and the next step is entered after the test meets the standard; the part that does not meet the test standard can be salvaged and flocculated, and the input amount of adsorbent and flocculant is increased until the test meets the standard; among the impurities of p-hydroxybenzoic acid: organic matter content: ≤1.0%; high salt content: sulfate content is ≤1%; strong alkali content: pH value is 6.5-9.5; the pretreated production water is introduced into the adsorption tank, the adsorption tank adopts a double-layer design, the upper layer is filled with macroporous adsorption resin, and a filter is set between the lower and upper layers, and the filter is covered with macroporous adsorption resin; when the pretreated water is introduced into the adsorption tank, multi-tube transportation is adopted, and the spacing at the bottom of the multi-transport pipe is set not less than 50cm; the macroporous adsorption resin is formed to adsorb the p-hydroxybenzoic acid component in the production water in multiple positions over a large area; the macroporous adsorption resin is NDA-101 resin, 717 resin, NDA-88 One or more of resin, CHA-101 resin, D201 resin and D301R resin; desorb and regenerate the saturated adsorption resin with hot alkali solution, then rinse with clean water to recover p-hydroxybenzoic acid and its intermediates; biochemically treat the effluent after desorption; ensure that the treated water quality meets the discharge standards or reuse requirements.

[0021] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for recovering p-hydroxybenzoic acid from p-hydroxybenzoic acid production water, characterized in that: The following steps are involved: Step 1: introduce the para-hydroxybenzoic acid production water into the aeration tank, put the adsorbent into the aeration tank, and perform aeration mixing; the adsorbent adsorbs high-concentration organic matter, high salt content, strong alkali and other substances in the para-hydroxybenzoic acid production water; by adding flocculants, floccules are formed in the production water, and the floccules are salvaged to achieve pretreatment of the production water; Step 2: Detect the organic matter, high salt content and strong alkali content in p-hydroxybenzoic acid by high performance liquid chromatography (HPLC), conductivity measurement and pH meter, and proceed to the next step after the test meets the standard; Step 3: Introduce the pretreated production water into the adsorption tank. The adsorption tank adopts a double-layer design. The upper layer is filled with macroporous adsorption resin, and a filter is set between the lower and upper layers. The filter is covered with macroporous adsorption resin; When the pre-treated water is introduced into the adsorption tank, it is transported by multiple pipes, and the spacing between the bottom ends of the multiple transport pipes is not less than 50 cm; thus, the macroporous adsorption resin is formed to adsorb the p-hydroxybenzoic acid component in the production water over a large area at multiple positions; Step 4: Desorb and regenerate the saturated adsorption resin using hot alkali solution, then rinse with clean water to recover p-hydroxybenzoic acid and its intermediates; Step 5: Biochemically treat the effluent after desorption to ensure that the treated water quality meets the discharge standards or reuse requirements.

2. The method for recovering p-hydroxybenzoic acid from p-hydroxybenzoic acid production water according to claim 1, characterized in that: In step 1, the adsorbent is in powder form, and the adsorbent is one or more of silica gel, alumina, activated carbon, polyacrylamide, zeolite molecular sieve and carbon molecular sieve.

3. The method for recovering p-hydroxybenzoic acid from p-hydroxybenzoic acid production water according to claim 1, characterized in that: In step 1, aeration and adsorbent are applied to produced water simultaneously, and aeration is configured to promote large-area contact between the adsorbent and produced water.

4. The method for recovering p-hydroxybenzoic acid from p-hydroxybenzoic acid production water according to claim 1, characterized in that: In step 1, after the flocculant is added, aeration is not stopped, and aeration is used to promote the full mixing of the flocculant and the suspended particles in the production water. After the flocculant is added, aeration is stopped and allowed to stand for 10-20 minutes, and the flocculant is configured to flocculate the suspended particles in the production water and the adsorbent.

5. The method for recovering p-hydroxybenzoic acid from p-hydroxybenzoic acid production water according to claim 1, characterized in that: In step 2, after the salvageable part that does not meet the standard is detected and flocculated, the input amount of adsorbent and flocculant is increased until the detection meets the standard; Among the impurities of p-hydroxybenzoic acid: The organic matter content must be ≤1.0%; High salt content: sulfate content is ≤1%; Strong alkaline content: pH value is 6.5-9.

5.

6. The method for recovering p-hydroxybenzoic acid from p-hydroxybenzoic acid production water according to claim 1, characterized in that: In step 3, the macroporous adsorption resin is one or more of NDA-101 resin, 717 resin, NDA-88 resin, CHA-101 resin, D201 resin and D301R resin.

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