Method for treating resin regeneration wastewater in inositol production

Abstract

The present application relates to the technical field of inositol production, and particularly relates to a resin regeneration wastewater treatment method in inositol production, which comprises the following contents: adding inositol solution into a neutralizing agent, filtering, collecting the filtrate, and passing the filtrate through a resin column group (one group of resin columns is used for feeding, and another group of resin columns is treated after regeneration); the cation resin column and the anion resin column in the another group of resin columns are respectively regenerated by using hydrochloric acid and potassium hydroxide solution, and then are eluted by using purified water; the regenerated concentrated solution and the regenerated washing solution are respectively collected; the regenerated concentrated solution of the cation resin column and the anion resin column after the regeneration treatment is mixed, filtered, and nanofiltered, and the cut-off liquid and the permeate are respectively collected; the regenerated washing solution of the cation resin column and the anion resin column after the regeneration treatment is mixed, filtered, and reverse osmosis treated, and the cut-off liquid and the permeate are respectively collected and used as resin regeneration water. The above treatment method reduces the wastewater discharge amount and the purified water consumption, realizes waste utilization, and improves economic benefits.

Description

Technical Field

[0001] This invention relates to the field of inositol production technology, and in particular to a method for treating resin regeneration wastewater in inositol production. Background Technology

[0002] In recent years, the production of inositol using potassium phytate as a raw material has become increasingly popular. Compared with traditional processes, its byproduct, potassium dihydrogen phosphate, has a wider range of applications, higher added value, and better economic benefits. The production process generally includes hydrolysis, filtration, simulated moving bed chromatography separation, concentration, crude crystallization, decolorization, recrystallization, centrifugation, and drying. Although the byproduct potassium dihydrogen phosphate is valuable, its hydrolysis rate is lower than that of calcium phytate due to its higher solubility in water. During simulated moving bed chromatography separation of the potassium phytate hydrolysate solution, some incompletely hydrolyzed potassium phytate, potassium dihydrogen phosphate, and amino acid residues remain in the inositol solution, affecting the inositol crystallization yield and product quality. Ion exchange resins can effectively remove these impurities remaining in the inositol solution, offering high removal efficiency and low operating costs.

[0003] After use, cation and anion exchange resins need to be regenerated with acid or alkali respectively before they can be reused. The wastewater generated during the regeneration process contains high concentrations of substances such as chlorine and phosphorus, especially phosphorus, which has a significant impact on environmental water bodies and is difficult to treat biochemically. Therefore, it is necessary to develop a method for treating resin regeneration wastewater in inositol production to address these issues. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for treating resin regeneration wastewater in inositol production, which addresses the shortcomings of the prior art. This wastewater treatment method greatly reduces the amount of wastewater discharged and enables the recycling of pollutants.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0006] A method for treating resin regeneration wastewater in inositol production includes the following steps:

[0007] (1) Take the inositol solution collected after separation, add a neutralizing agent, filter after the reaction is complete, and collect the precipitate and filtrate respectively;

[0008] (2) Take the filtrate from step (1) and put it into the resin column group. Collect the effluent for later use. The resin column group includes two groups, each of which includes a cation exchange resin column and an anion exchange resin column. The filtrate enters the cation exchange resin column of one group and then enters the anion exchange resin column. The inositol solution flowing out is collected. The cation exchange resin column of the other group is regenerated with hydrochloric acid. The regenerated concentrate flowing out is collected and then rinsed with purified water. The regenerated wash solution flowing out is collected. The anion exchange resin column is regenerated with potassium hydroxide solution. The regenerated concentrate flowing out is collected and then rinsed with purified water. The regenerated wash solution flowing out is collected.

[0009] (3) Mix the regenerated concentrate after the regeneration treatment of the cation resin column and the anion resin column in step (2), control the pH, filter and then enter the nanofiltration membrane system, and collect the retentate and permeate respectively.

[0010] (4) Take the permeate collected in step (3), concentrate, cool, crystallize, centrifuge and dry to obtain potassium chloride product;

[0011] (5) Mix the regeneration wash liquid after the regeneration treatment of the cation resin column and the anion resin column in step (2), filter it and enter the reverse osmosis system. The collected retentate is combined with the retentate in step (3) for later use. The collected permeate is used as resin regeneration water.

[0012] As an improved technical solution, the neutralizing agent in step (1) is calcium oxide, calcium hydroxide or calcium carbonate, and the neutralizing agent is 2-4‰ (W / V) of the volume of the inositol solution.

[0013] As an improved technical solution, the reaction time in step (1) is 0.5-2h, and the pH of the solution after the reaction is completed is 8-10.

[0014] As an improved technical solution, in step (2), the filtrate enters the cation exchange resin column at a flow rate of 1-2 BV / h, and the collected effluent then enters the anion exchange resin column at a flow rate of 1-2 BV / h, and the effluent is an inositol solution.

[0015] As an improved technical solution, the inositol solution collected in step (2) has a conductivity of 20-100 μs / cm, a transmittance of 99-100%, and an inositol purity of ≥98%.

[0016] As an improved technical solution, in step (2), the concentrations of hydrochloric acid and potassium hydroxide solution are both 1-2 mol / L, the flow rates into the resin column are 1-2 BV / h, and the amounts used are 2-3 BV of the resin column volume.

[0017] As an improved technical solution, in step (2), the flow rates of purified water entering the cation exchange resin column and the anion exchange resin column are 1-3 BV / h, respectively. The pH of the regeneration wash solution flowing out of the cation exchange resin column is 4-6, and the conductivity is 60-100 μs / cm. The pH of the regeneration wash solution flowing out of the anion exchange resin column is 8-10, and the conductivity is 60-100 μs / cm.

[0018] As an improved technical solution, in step (3), the pH of the regenerated concentrate after mixing is controlled at 7-10, and the solid content is 2-4wt%; the operating pressure of the nanofiltration membrane system is 2-3MPa, and the molecular weight cutoff of the nanofiltration membrane is 300-400Da.

[0019] As an improved technical solution, in step (5), the pH of the regenerated washing solution after mixing is controlled at 5-7, and the solid content is 0.1-0.5wt%.

[0020] As an improved technical solution, in step (5), the operating pressure of the reverse osmosis system is 3-5 MPa, and the ratio of retentate to permeate is controlled at 1:4-5.

[0021] After adopting the above technical solution, the beneficial effects of the present invention are:

[0022] This invention involves adding a neutralizing agent to the separated and collected inositol solution. After the neutralization reaction, the solution is filtered. The collected filtrate is passed through a resin column assembly (one set of resin columns is used for feeding, and the other set is used for regeneration and post-treatment), and the inositol-containing effluent is collected. The cation exchange resin column in the other set is regenerated with hydrochloric acid and then rinsed with purified water, with the regenerated concentrate and regeneration wash solution collected separately. The anion exchange resin column is regenerated with potassium hydroxide solution and then rinsed with purified water, with the regenerated concentrate and regeneration wash solution collected separately. The regenerated concentrates from the cation and anion exchange resin columns are mixed, filtered, and nanofiltered, with the retentate and permeate collected separately (after concentration, cooling, and crystallization, potassium chloride is obtained). The regeneration wash solutions from the cation and anion exchange resin columns are mixed, filtered, and treated with reverse osmosis. The collected retentate is combined with the retentate collected by the nanofiltration system, and the collected permeate is used as resin regeneration water. This treatment method reduces wastewater discharge and purified water consumption, lowers production costs, recovers pollutants from wastewater, achieves waste utilization, and improves economic efficiency. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0024] Example 1

[0025] A method for treating resin regeneration wastewater in inositol production includes the following steps:

[0026] (1) Take 1000L of the inositol solution collected after separation (inositol content 70g / L, salt content 3g / L), add 2kg of neutralizing agent (calcium oxide) at 2‰ of the volume of the inositol solution, react for 0.5h, and filter the liquid with pH 8 using plate and frame filtration (filter cloth pore size 400-600 mesh), and collect 5kg of precipitate (calcium carbonate as feed additive) and 1000L of filtrate respectively.

[0027] (2) Take 1000L of the filtrate from step (1) and enter the resin column group (including two groups, each group of resin columns includes a cation exchange resin column and an anion exchange resin column). The filtrate enters the cation exchange resin column of one group (the resin column volume is 100L) at a flow rate of 1BV / h, and then enters the anion exchange resin column (the resin column volume is 100L) at a flow rate of 1BV / h. Collect the 1000L inositol solution (conductivity 60μs / cm, transmittance 99.5%, inositol purity 98.5%). Regenerate the cation exchange resin column (volume is 100L) of the other group by adding 1mol / L hydrochloric acid (flow rate 2BV / h, and the amount is 3BV of the resin column volume). The column was treated by adding 1 BV of purified water to rinse the resin column. The 400 L of regenerated concentrate was collected and then rinsed with another 400 L of purified water (flow rate 1 BV / h). The 400 L of regenerated wash solution with pH 6 and conductivity 60 μS / cm was collected. The anion exchange resin column (volume 400 L) was regenerated by adding 1 mol / L potassium hydroxide solution (flow rate 2 BV / h, and the amount used was 3 BV of the resin column volume). The column was then rinsed with 1 BV of purified water. The 400 L of regenerated concentrate was collected and then rinsed with another 600 L of purified water. The 600 L of regenerated wash solution with pH 8 and conductivity 60 μS / cm was collected.

[0028] (3) Mix the regenerated concentrate after the regeneration treatment of the cation resin column and the anion resin column in step (2) (solid content 2wt%), control the pH at 7, filter (precision filter with filter element pore size 0.5-1 micrometer) and then enter the nanofiltration membrane system (operating pressure 2MPa, nanofiltration membrane molecular weight cutoff 300-400Da), and collect 200L of retentate and 600L of permeate respectively.

[0029] (4) Take 600L of the permeate collected in step (3), concentrate it (vacuum degree -0.07MPa, temperature 80℃, solid content of concentrate 40wt%), cool it to 25℃, crystallize for 8h, centrifuge, and dry it (using vibrating fluidized bed drying, inlet air temperature 130℃, outlet air temperature 65℃, drying time 3min) to obtain potassium chloride product. The crystallization mother liquor collected by centrifugation is returned to the concentration process.

[0030] (5) Mix the regeneration wash liquid after the regeneration treatment of the cation resin column and the anion resin column in step (2) (solid content is 0.1wt%), control the pH at 7, filter (precision filter with filter element pore size of 0.5-1 micrometer) and enter the reverse osmosis system (operating pressure 3MPa, control the ratio of retentate to permeate to 1:5). The collected retentate is combined with the retentate in step (3) for later use (concentrated and sold as liquid organic fertilizer). The collected permeate 835L is used as resin regeneration water.

[0031] Example 2

[0032] A method for treating resin regeneration wastewater in inositol production includes the following steps:

[0033] (1) Take 1000L of the inositol solution collected after separation (inositol content 70g / L, salt content 3g / L), add 2.5kg of neutralizing agent (calcium hydroxide) at 2.5‰ of the volume of the inositol solution, react for 1h, and filter the liquid with pH 8.5 using plate and frame filtration (filter cloth pore size 400-600 mesh), and collect 6kg of precipitate (calcium carbonate as feed additive) and 1000L of filtrate respectively;

[0034] (2) Take 1000L of the filtrate from step (1) and enter it into the resin column group (including two groups, each group of resin columns includes a cation exchange resin column and an anion exchange resin column). The filtrate enters the cation exchange resin column of one group (resin column volume is 100L) at a flow rate of 1.2BV / h, and then enters the anion exchange resin column (resin column volume is 100L) at a flow rate of 1.2BV / h. Collect the 1000L of inositol solution (conductivity 40μs / cm, transmittance 99.7%, inositol purity 98.8%) flowing out. Add 1.2mol / L hydrochloric acid (flow rate 1.8BV / h, and the amount used is 2.8BV of the resin column volume) to the cation exchange resin column of the other group (volume is 380L) for regeneration. The resin column (100 L) was regenerated by adding 1 BV of purified water to the resin column and rinsing. The 400 L of regenerated concentrate was collected and then rinsed with another 400 L of purified water (flow rate 1.5 BV / h). The 400 L of regenerated wash solution with pH 5.5 and conductivity 70 μS / cm was collected. The anion exchange resin column (100 L) was regenerated by adding 1.2 mol / L potassium hydroxide solution (flow rate 1.8 BV / h, and the amount added was 2.8 BV of the resin column volume). The column was then rinsed with 1 BV of purified water and the 380 L of regenerated concentrate was collected and then rinsed with another 600 L of purified water. The 600 L of regenerated wash solution with pH 8.5 and conductivity 70 μS / cm was collected.

[0035] (3) Mix the regenerated concentrate after the regeneration treatment of the cation resin column and the anion resin column in step (2) (solid content 2.5wt%), control the pH at 8, filter (precision filter with filter element pore size 0.5-1 micrometer) and then enter the nanofiltration membrane system (operating pressure 2.3MPa, nanofiltration membrane molecular weight cutoff 300-400Da), and collect 190L of retentate and 570L of permeate respectively.

[0036] (4) Take 570L of the permeate collected in step (3), concentrate it (vacuum degree -0.07MPa, temperature 82℃, solid content of concentrate 42wt%), cool it to 28℃, crystallize for 9h, centrifuge, and dry it (using vibrating fluidized bed drying, inlet air temperature 135℃, outlet air temperature 68℃, drying time 5min) to obtain potassium chloride product. The crystallization mother liquor collected by centrifugation is returned to the concentration process.

[0037] (5) Mix the regeneration wash liquid after the regeneration treatment of the cation resin column and the anion resin column in step (2) (solid content is 0.2wt%), control the pH at 6.5, filter (precision filter with filter element pore size of 0.5-1 micrometer) and enter the reverse osmosis system (operating pressure 3.5MPa, control the ratio of retentate to permeate to 1:4.8, the collected retentate is combined with the retentate in step (3) for later use (concentrated and sold as liquid organic fertilizer), and the collected permeate 830L is used as resin regeneration water.

[0038] Example 3

[0039] A method for treating resin regeneration wastewater in inositol production includes the following steps:

[0040] (1) Take 1000L of the inositol solution collected after separation (inositol content 70g / L, salt content 3g / L), add 3kg of neutralizing agent (calcium hydroxide) at 3‰ of the volume of the inositol solution, react for 1.2h, and filter the liquid with pH 9 using plate and frame filtration (filter cloth pore size 400-600 mesh), and collect 7.2kg of precipitate (calcium carbonate as feed additive) and 1000L of filtrate respectively;

[0041] (2) Take 1000L of the filtrate from step (1) and enter it into the resin column group (including two groups, each group of resin columns includes a cation exchange resin column and an anion exchange resin column). The filtrate enters the cation exchange resin column of one group (the resin column volume is 100L) at a flow rate of 1.5BV / h, and then enters the anion exchange resin column (the resin column volume is 100L) at a flow rate of 1.5BV / h. Collect the 1000L of inositol solution (conductivity 20μs / cm, transmittance 100%, inositol purity 99%) flowing out. Regenerate the cation exchange resin column (volume is 100L) of the other group by adding 1.5mol / L hydrochloric acid (flow rate 1.5BV / h, and the amount is 2BV of the resin column volume). The regeneration process involves adding 1 BV of purified water to the resin column for rinsing. The resulting 300 L of regenerated concentrate is collected and then rinsed with 400 L of purified water (flow rate 2 BV / h). The resulting 400 L of regeneration wash solution with pH 5 and conductivity 80 μS / cm is collected. For the anion exchange resin column (100 L), regeneration is performed by adding 1.5 mol / L potassium hydroxide solution (flow rate 1.5 BV / h, volume 2 BV of the resin column). The column is then rinsed with 1 BV of purified water, and the resulting 300 L of regenerated concentrate is collected and then rinsed with 600 L of purified water. The resulting 600 L of regeneration wash solution with pH 9 and conductivity 80 μS / cm is collected.

[0042] (3) Mix the regenerated concentrate after the regeneration treatment of the cation resin column and the anion resin column in step (2) (solid content 3wt%), control the pH at 8.5, filter (precision filter with filter element pore size of 0.5-1 micrometer) and then enter the nanofiltration membrane system (operating pressure 2.5MPa, nanofiltration membrane molecular weight cutoff of 300-400Da), and collect 150L of retentate and 450L of permeate respectively.

[0043] (4) Take 450L of the permeate collected in step (3), concentrate it (vacuum degree -0.08MPa, temperature 85℃, solid content of concentrate 48wt%), cool it to 30℃, crystallize it for 10h, centrifuge it, and dry it (using vibrating fluidized bed drying, inlet air temperature 140℃, outlet air temperature 70℃, drying time 4min) to obtain potassium chloride product. The crystallization mother liquor collected by centrifugation is returned to the concentration process.

[0044] (5) Mix the regeneration wash liquid after the regeneration treatment of the cation resin column and the anion resin column in step (2) (solid content is 0.3wt%), control the pH at 6, filter (precision filter with filter element pore size of 0.5-1 micrometer) and enter the reverse osmosis system (operating pressure 4MPa, control the ratio of retentate to permeate to 1:4.5). The collected retentate is combined with the retentate in step (3) for later use (concentrated and sold as liquid organic fertilizer). The collected permeate 820L is used as resin regeneration water.

[0045] Example 4

[0046] A method for treating resin regeneration wastewater in inositol production includes the following steps:

[0047] (1) Take 1000L of the inositol solution collected after separation (inositol content 70g / L, salt content 3g / L), add 3.5kg of neutralizing agent (calcium carbonate) at 3.5‰ of the volume of the inositol solution, react for 1.5h, and the resulting liquid with pH 9.5 is filtered by plate and frame filtration (filter cloth pore size 400-600 mesh), and collect 8.5kg of precipitate (calcium carbonate as a feed additive component) and 1000L of filtrate respectively;

[0048] (2) Take 1000L of the filtrate from step (1) and enter the resin column group (including two groups, each group of resin columns includes a cation exchange resin column and an anion exchange resin column). The filtrate enters the cation exchange resin column of one group (resin column volume is 100L) at a flow rate of 1.8BV / h, and then enters the anion exchange resin column (resin column volume is 100L) at a flow rate of 1.8BV / h. Collect the 1000L of inositol solution flowing out (conductivity 85μs / cm, transmittance 99.3%, inositol purity 98.3%). Add 1.8mol / L hydrochloric acid (flow rate 1.2BV / h, and amount is 2.5BV of resin column volume) to the cation exchange resin column of the other group (volume is 100L) for regeneration. The resin column (100 L) was regenerated by adding 1 BV of purified water to the resin column and rinsing. The 350 L of regenerated concentrate was collected and then rinsed with 400 L of purified water (flow rate 2.5 BV / h). The 400 L of regenerated wash solution with pH 4.5 and conductivity 90 μS / cm was collected. The anion exchange resin column (100 L) was regenerated by adding 1.8 mol / L potassium hydroxide solution (flow rate 1.2 BV / h, and the amount added was 2.5 BV of the resin column volume), and then rinsed with 1 BV of purified water. The 350 L of regenerated concentrate was collected and then rinsed with 600 L of purified water. The 600 L of regenerated wash solution with pH 9.5 and conductivity 90 μS / cm was collected.

[0049] (3) Mix the regenerated concentrate after the regeneration treatment of the cation resin column and the anion resin column in step (2) (solid content 3.5wt%), control the pH at 9, filter (precision filter with filter element pore size 0.5-1 micrometer) and then enter the nanofiltration membrane system (operating pressure 2.8MPa, nanofiltration membrane molecular weight cutoff 300-400Da), and collect 170L of retentate and 530L of permeate respectively.

[0050] (4) Take 530L of the permeate collected in step (3), concentrate it (vacuum degree -0.08MPa, temperature 88℃, solid content of concentrate 48wt%), cool it to 32℃, crystallize it for 11h, centrifuge it, and dry it (using vibrating fluidized bed drying, inlet air temperature 145℃, outlet air temperature 72℃, drying time 4min) to obtain potassium chloride product. The crystallization mother liquor collected by centrifugation is returned to the concentration process.

[0051] (5) Mix the regeneration wash liquid after the regeneration treatment of the cation resin column and the anion resin column in step (2) (solid content is 0.4wt%), control the pH at 5.5, filter (precision filter with filter element pore size of 0.5-1 micrometer) and enter the reverse osmosis system (operating pressure 4.5MPa, control the ratio of retentate to permeate to 1:4.2), combine the collected retentate with the retentate in step (3) for later use (concentrated and sold as liquid organic fertilizer), and use the collected permeate 810L as resin regeneration water.

[0052] Example 5

[0053] A method for treating resin regeneration wastewater in inositol production includes the following steps:

[0054] (1) Take 1000L of the inositol solution collected after separation (inositol content is 70g / L, salt content is 3g / L), add 4kg of neutralizing agent (calcium oxide) at 4‰ of the volume of the inositol solution, react for 2h, and filter the liquid with pH 10 by plate and frame filtration (filter cloth pore size 400-600 mesh), and collect 10kg of precipitate (calcium carbonate as feed additive) and 1000L of filtrate respectively.

[0055] (2) Take 1000L of the filtrate from step (1) and put it into the resin column group (including two groups, each group of resin columns includes a cation exchange resin column and an anion exchange resin column). The filtrate enters the cation exchange resin column of one group (the resin column volume is 100L) at a flow rate of 2BV / h, and then enters the anion exchange resin column (the resin column volume is 100L) at a flow rate of 2BV / h. Collect the 1000L of inositol solution (conductivity 100μs / cm, transmittance 99%, inositol purity 98%). The cation exchange resin column of the other group (volume is 100L) is regenerated by adding 2mol / L hydrochloric acid (flow rate 1BV / h, and the amount is 2.3BV of the resin column volume). The resin column was rinsed with 1 BV of purified water. The 330 L of regenerated concentrate was collected and then rinsed with 400 L of purified water (flow rate 3 BV / h). The 400 L of regenerated wash solution with pH 4 and conductivity 100 μS / cm was collected. The anion exchange resin column (volume 100 L) was regenerated with 2 mol / L potassium hydroxide solution (flow rate 2 BV / h, and the amount used was 2.3 BV of the resin column volume). The column was then rinsed with 1 BV of purified water. The 330 L of regenerated concentrate was collected and then rinsed with 600 L of purified water. The 600 L of regenerated wash solution with pH 10 and conductivity 100 μS / cm was collected.

[0056] (3) Mix the regenerated concentrate after the regeneration treatment of the cation resin column and the anion resin column in step (2) (solid content 4wt%), control the pH at 10, filter (precision filter with filter element pore size 0.5-1 micrometer) and then enter the nanofiltration membrane system (operating pressure 3MPa, nanofiltration membrane molecular weight cutoff 300-400Da), and collect 160L of retentate and 500L of permeate respectively.

[0057] (4) Take 500L of the permeate collected in step (3), concentrate it (vacuum degree -0.09MPa, temperature 90℃, solid content of concentrate 50wt%), cool it to 35℃, crystallize for 12h, centrifuge, and dry it (using vibrating fluidized bed drying, inlet air temperature 150℃, outlet air temperature 75℃, drying time 3min) to obtain potassium chloride product. The crystallization mother liquor collected by centrifugation is returned to the concentration process.

[0058] (5) Mix the regeneration wash liquid after the regeneration treatment of the cation resin column and the anion resin column in step (2) (solid content is 0.5wt%), control the pH at 5, filter (precision filter with filter element pore size of 0.5-1 micrometer) and enter the reverse osmosis system (operating pressure 5MPa, control the ratio of retentate to permeate to 1:4). The collected retentate is combined with the retentate in step (3) for later use (concentrated and sold as liquid organic fertilizer). The collected permeate 800L is used as resin regeneration water.

[0059] To better demonstrate that the treatment method of the present invention can reduce wastewater discharge and purified water consumption, and also achieve waste recycling, 11 comparative examples are given with reference to Example 3, as detailed below:

[0060] Comparative Example 1

[0061] Unlike Example 3, the hydrochloric acid concentration used in step (2) during the regeneration of the cation exchange resin column was 0.5 mol / L, while the rest of the operation was the same.

[0062] Comparative Example 2

[0063] Unlike Example 3, the concentration of potassium hydroxide solution used in step (2) during the regeneration of the anion exchange resin column is 0.5 mol / L, while the rest of the operation is the same.

[0064] Comparative Example 3

[0065] Unlike Example 3, the molecular weight cutoff of the nanofiltration membrane in step (3) is less than 300 Da, while the rest of the operation is the same.

[0066] Comparative Example 4

[0067] Unlike Example 3, the nanofiltration membrane in step (3) has a molecular weight cutoff greater than 400 Da, while the rest of the operation is the same.

[0068] Comparative Example 5

[0069] Unlike Example 3, in step (3), the pH of the regenerated concentrate is controlled at 6 after mixing, while the rest of the operation is the same.

[0070] Comparative Example 6

[0071] Unlike Example 3, in step (5), the pH of the regenerated washing solution is controlled at 4 after mixing, while the rest of the operation is the same.

[0072] Comparative Example 7

[0073] Unlike Example 3, in step (5), the ratio of retentate to permeate is controlled to be 1:3 after the reverse osmosis membrane system is treated, and the rest of the operation is the same.

[0074] Comparative Example 8

[0075] Unlike Example 3, the flow rate of hydrochloric acid in step (2) is 2.5 BV / h, while the rest of the operation is the same.

[0076] Comparative Example 9

[0077] Unlike Example 3, the flow rate of the potassium hydroxide solution in step (3) is 2.5 BV / h, while the rest of the operation is the same.

[0078] Comparative Example 10

[0079] Unlike Example 3, the regenerated concentrate recovery process in steps (3) and (4) is omitted, while the rest of the operations are the same.

[0080] Comparative Example 11

[0081] Unlike Example 3, the regeneration washing liquid recovery step in step (5) is omitted, while the rest of the operation is the same.

[0082] Table 1

[0083]

[0084] As can be seen from the data in Table 1, considering factors such as wastewater discharge, purified water consumption, byproduct potassium chloride yield, inositol yield, and inositol purity, Example 3 is the optimal example for the wastewater treatment method of this invention. Comparing Example 3 with Comparative Examples 1-11 reveals that the wastewater treatment method of this invention can reduce wastewater discharge and purified water consumption, while increasing the yield of byproduct potassium chloride, inositol yield, and inositol purity.

[0085] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for treating resin regeneration wastewater in inositol production, characterized by, The method comprises the following steps: (1) taking the collected myo-inositol solution after separation, adding a neutralizing agent, filtering after reaction, and collecting the precipitate and filtrate respectively; (2) taking the filtrate in step (1) into a resin column group, and collecting the effluent for use; the resin column group comprises two groups, each group of resin column comprises a cation resin column and an anion resin column; the filtrate enters the cation resin column of one group, and then enters the anion resin column, and the myo-inositol solution flowing out is collected; the cation resin column of the other group is added with hydrochloric acid for regeneration treatment, the regenerated concentrated solution flowing out is collected, and then purified water is added for elution, and the regenerated eluate flowing out is collected; the anion resin column is added with potassium hydroxide solution for regeneration treatment, the regenerated concentrated solution flowing out is collected, and then purified water is added for elution, and the regenerated eluate flowing out is collected; (3) mixing the regenerated concentrated solutions of the cation resin column and the anion resin column after regeneration treatment in step (2), controlling the pH, filtering, and then entering a nanofiltration membrane system, and collecting the retentate and the permeate respectively; (4) taking the collected permeate in step (3), and obtaining the potassium chloride product through concentration, cooling, crystallization, centrifugation and drying; (5) mixing the regenerated eluate of the cation resin column and the anion resin column after regeneration treatment in step (2), filtering, and then entering a reverse osmosis system, collecting the retentate for use together with the retentate in step (3), and collecting the permeate as resin regeneration water.

2. The method for treating wastewater from resin regeneration in inositol production according to claim 1, characterized by, The neutralizing agent in step (1) is calcium oxide, calcium hydroxide or calcium carbonate, and the neutralizing agent is 2-4 ‰ (W / V) of the volume of the myo-inositol solution.

3. The method of claim 1, wherein the resin regeneration wastewater is treated by a method comprising: The reaction time in step (1) is 0.5-2 h, and the pH of the material liquid after reaction is 8-10. ​ 4. The method of claim 1, wherein the resin regeneration wastewater is treated by a method comprising: In step (2), the filtrate enters the cation resin column at a flow rate of 1-2 BV / h, the effluent collected enters the anion resin column at a flow rate of 1-2 BV / h, and the myo-inositol solution flowing out is collected. ​ 5. The method of claim 1, wherein the resin regeneration wastewater is treated by a method comprising: The conductivity of the myo-inositol solution collected in step (2) is 20-100 μs / cm, the transmittance is 99-100%, and the purity of myo-inositol is ≥98%. ​ 6. The method for treating wastewater from resin regeneration in inositol production according to claim 1, characterized by, In step (2), the concentration of hydrochloric acid and potassium hydroxide solution is 1-2 mol / L, the flow rate entering the resin column is 1-2 BV / h respectively, and the amount is 2-3 BV of the volume of the resin column respectively.

7. The method of claim 1, wherein the resin regeneration wastewater is treated by a method comprising: In step (2), the flow rate of purified water entering the cation resin column and the anion resin column is 1-3 BV / h respectively, the pH of the regenerated eluate flowing out of the cation resin column is 4-6, and the conductivity is 60-100 μs / cm; the pH of the regenerated eluate flowing out of the anion resin column is 8-10, and the conductivity is 60-100 μs / cm. ​ 8. The method of claim 1, wherein the resin regeneration wastewater is treated by a method comprising: In step (3), the pH of the mixed regenerated concentrated solution is controlled at 7-10, and the solid content is 2-4 wt%; the operating pressure of the nanofiltration membrane system is 2-3 MPa, and the molecular weight cut-off of the nanofiltration membrane is 300-400 Da. ​ 9. The method of claim 1, wherein the resin regeneration wastewater is treated by a method comprising: In step (5), the pH of the mixed regenerated eluate is controlled at 5-7, and the solid content is 0.1-0.5 wt%. ​ 10. The method for treating wastewater from resin regeneration in inositol production according to claim 1, characterized by, In step (5), the operating pressure of the reverse osmosis system is 3-5 MPa, and the ratio of the retentate to the permeate is controlled at 1:4-5.

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