Enzymatic post-desorption liquid waste treatment process

Abstract

The application provides an enzyme desorption post-liquid wastewater treatment process and belongs to the technical field of wastewater treatment.The process comprises a fatty acid recovery unit, a salt water recovery unit and an amino acid recovery unit.The enzyme desorption post-liquid wastewater treatment process can recycle fatty acid, amino acid and sodium chloride in enzyme desorption post-liquid wastewater, effectively reduces the treatment load of a sewage treatment station, expands 50% of the sewage treatment capacity under the premise of ensuring stable operation of the sewage station and has remarkable economic benefits.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to a process for treating wastewater after enzymatic desorption. Background Technology

[0002] Enzymatic hydrolysis post-adsorption wastewater refers to the high-concentration organic wastewater generated after the enzymatic hydrolysis and adsorption process of crude heparin sodium. This wastewater contains large amounts of fatty acids, amino acids, and sodium chloride, and is characterized by high chemical oxygen demand (COD), high salinity, and high perishability. Current methods for treating this wastewater mainly involve direct discharge into wastewater treatment plants for treatment using processes such as air flotation and biological treatment before discharge. However, according to on-site operational data from wastewater treatment plants, the salinity of the influent is already approaching the tolerance limit of biological treatment methods, while the treatment capacity is only about half of the design value. Furthermore, the fatty acids, amino acids, and other organic matter in the enzymatic hydrolysis wastewater are not being utilized as resources, and they also increase the organic load on the biological treatment system of the wastewater treatment plant. Therefore, the treatment of enzymatic hydrolysis wastewater directly limits the further improvement of enterprise production capacity.

[0003] Therefore, it is of great significance to provide a wastewater treatment process for enzymatic desorption liquid that can both recover fatty acids, amino acids, and sodium chloride from the enzymatic desorption liquid wastewater in a resource-efficient manner, thereby improving the economic benefits of enterprises, and at the same time reduce the treatment load of sewage treatment plants and improve their wastewater treatment capacity. Summary of the Invention

[0004] In view of this, the present invention provides a process for treating wastewater after enzyme desorption, comprising the following steps:

[0005] (1) Fatty acid recovery

[0006] Calcium chloride was added to the wastewater after enzyme desorption, and the mixture was allowed to stand for a period of time. Solid-liquid separation was then performed to obtain a clear liquid and a water-containing solid. The water-containing solid was then pressed and dehydrated to obtain fatty acids.

[0007] (2) Brine recovery

[0008] The clear liquid described in step (1) is filtered and separated to obtain concentrated water a and permeate a. The permeate a is sterilized and then reused in the workshop.

[0009] (3) Amino acid recovery

[0010] Calcium chloride is added to the concentrated water a in step (2), filtered, and precipitate and filtrate are obtained. The precipitate is returned to the solid-liquid separation process for further processing. The filtrate is subjected to graded filtration to obtain concentrated water b and permeate b. The concentrated water b is evaporated at low temperature to obtain condensate and salt-containing amino acids. Both permeate b and condensate are sent to the sewage treatment plant for sewage treatment.

[0011] Furthermore, the amount of calcium chloride added in step (1) is 3 kg / t to 8 kg / t.

[0012] Furthermore, the settling time in step (1) is 6-12 hours.

[0013] Furthermore, the water content in the aqueous solid in step (1) is 75-88%, and the water content in the fatty acid is 50%-55%.

[0014] Furthermore, the solid-liquid separation in step (1) is performed using a horizontal screw centrifuge or a vacuum ceramic filter.

[0015] Furthermore, the filtration and separation step in step (2) includes: passing the clear liquid sequentially through a bag filter, a precision filter, and a primary nanofiltration process.

[0016] Furthermore, the sterilization in step (2) is carried out by ultraviolet sterilization, ozone oxidation, microporous filtration or pasteurization.

[0017] Furthermore, the amount of calcium chloride added in step (3) is 0.5 kg / t to 3 kg / t.

[0018] Furthermore, the graded filtration process in step (3) is as follows: the filtrate is sequentially passed through a bag filter, a precision filter, and a secondary nanofiltration process.

[0019] Furthermore, the process parameters for low-temperature evaporation in step (3) are: temperature 40-50℃, time 8-10 hours.

[0020] Furthermore, the equipment for low-temperature evaporation described in step (3) is equipped with a spiral scraper inside.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The enzymatic desorption wastewater treatment process provided by this invention can recover fatty acids, amino acids and sodium chloride from the enzymatic desorption wastewater in a resource-based manner, which has significant economic benefits. At the same time, it can also effectively reduce the treatment load of the sewage treatment plant and expand the sewage treatment capacity by 50% while ensuring the stable operation of the sewage treatment plant. Detailed Implementation

[0023] This invention provides a process for treating wastewater after enzyme desorption, comprising the following steps:

[0024] (1) Fatty acid recovery

[0025] Calcium chloride was added to the wastewater after enzyme desorption, and the mixture was allowed to stand for a period of time. Solid-liquid separation was then performed to obtain a clear liquid and a water-containing solid. The water-containing solid was then pressed and dehydrated to obtain fatty acids.

[0026] (2) Brine recovery

[0027] The clear liquid described in step (1) is filtered and separated to obtain concentrated water a and permeate a. The permeate a is sterilized and then reused in the workshop.

[0028] (3) Amino acid recovery

[0029] Calcium chloride is added to the concentrated water a in step (2), filtered, and precipitate and filtrate are obtained. The precipitate is returned to the solid-liquid separation process for further processing. The filtrate is subjected to graded filtration to obtain concentrated water b and permeate b. The concentrated water b is evaporated at low temperature to obtain condensate and salt-containing amino acids. Both permeate b and condensate are sent to the sewage treatment plant for sewage treatment.

[0030] In some embodiments of the present invention, the amount of calcium chloride added in step (1) is 3 kg / t to 8 kg / t, preferably, the amount of calcium chloride added in step (1) is 5 kg / t.

[0031] This invention utilizes calcium chloride to disrupt the stability of colloids in the enzymatic desorption wastewater, promoting their coagulation. Simultaneously, the added calcium ions react with amino acids in the wastewater to form complexes, which improves subsequent nanofiltration separation. After the chemical reaction, the mixture needs to stand for several hours, employing multiple tanks equipped with agitators for integrated collection and reaction.

[0032] In some embodiments of the present invention, the settling time in step (1) is 6-12 hours, preferably 8 hours.

[0033] In some embodiments of the present invention, the water content in the aqueous solid in step (1) is 75-88%, and the water content in the fatty acid is 50%-55%. Preferably, the water content in the aqueous solid in step (1) is 86%, and the water content in the fatty acid is 55%.

[0034] In some embodiments of the present invention, the solid-liquid separation in step (1) is performed using a horizontal screw centrifuge or a vacuum ceramic filter.

[0035] In some embodiments of the present invention, the filtration and separation step (2) includes: passing the clear liquid sequentially through a bag filter, a precision filter and a first-stage nanofiltration process.

[0036] The present invention does not impose strict limitations on the sterilization method. All commonly used sterilization methods in the field are applicable to the present invention. Preferably, the sterilization in step (2) is carried out by ultraviolet (UV) sterilization, ozone oxidation, 0.22 µm microporous filtration or pasteurization.

[0037] In some embodiments of the present invention, the amount of calcium chloride added in step (3) is 0.5 kg / t to 3 kg / t, preferably 1 kg / t. The concentrated water a after primary nanofiltration is yellow and turbid. Adding calcium chloride will clarify the reaction and reduce the load on subsequent treatments.

[0038] In some embodiments of the present invention, the graded filtration process in step (3) is as follows: the filtrate is sequentially passed through a bag filter, a precision filter and a secondary nanofiltration process.

[0039] In this invention, bag filters are used to remove coarse suspended solids and fibrous, particulate impurities (with a typical particle size of 50–200 µm) from the raw liquid, in order to protect downstream equipment and significantly reduce the impact and clogging of precision filters by flocs and large particles.

[0040] In this invention, a precision filter is used to further remove fine suspended solids, emulsified oil droplets, and colloidal particles (the filtration accuracy is typically 1–10 µm, preferably 1–5 µm), so that the turbidity and particle count after filtration meet the requirements of nanofiltration feed water, thereby reducing the nanofiltration membrane fouling rate and improving flux stability.

[0041] In this invention, primary nanofiltration is used to initially concentrate and separate oily / organic liquids, retaining high molecular weights, organic acids (such as some fatty acids, amino acid polymers, etc.) and divalent / polyvalent ions, reducing the organic load of the raw liquid and recovering high-value components. The permeate is used as feed water for subsequent treatments (such as sterilization, reuse or further purification), and the concentrate is used for the next step of treatment or resource recovery.

[0042] In this invention, secondary nanofiltration is used to polish the primary nanofiltration permeate or fine filtrate to a higher purity, further removing low molecular weight organic matter, color and residual inorganic salts, improving the clarity of the effluent, reducing conductivity and COD, and enabling the permeate to meet the required reuse or discharge standards; at the same time, the concentrate from secondary nanofiltration can be recovered as a concentrate or enter the subsequent purification process.

[0043] In some embodiments of the present invention, the process parameters for the low-temperature evaporation in step (3) are: temperature 40-50°C and time 8-10 hours. Preferably, the process parameters for the low-temperature evaporation in step (3) are: temperature 40°C and time 8 hours.

[0044] In some embodiments of the present invention, the device for low-temperature evaporation in step (3) is equipped with a spiral scraper.

[0045] The organic matter concentration of the secondary nanofiltration concentrate b is relatively high, and it becomes viscous after evaporation and concentration. Therefore, this invention uses a low-temperature evaporation crystallization kettle with an internal spiral scraper, which facilitates material discharge, prevents clogging, and provides better condensate quality than other types of evaporators.

[0046] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0047] Unless otherwise specified, the test methods or experimental methods described in the following examples are all conventional methods; unless otherwise specified, the raw materials and additives are obtained from conventional commercial sources or prepared by conventional methods.

[0048] The list of equipment used in this invention is shown in Table 1.

[0049] Table 1

[0050] Serial Number Main equipment name Main specifications quantity Remark Fatty acid recovery unit 1 Original liquid reaction tank <![CDATA[V=50m 3 Includes a 15kW mixer, made of PPH material. 3 sets Mutual backup 2 screw pump <![CDATA[10m 3 / h, 0.6MPa, 4kW, material 2205 2 units 3 Horizontal centrifuge <![CDATA[10m 3 / h, 55+45kW, material 2205]]> 1 set 4 Hydraulic pressing 300L 80t, 4kW, 316L material 1 set 5 Calcium chloride dosing <![CDATA[2m 3 / h,V=5m 3 ]]> 1 set brine recovery unit 1 bag filter 30μm 2 sets Mutual backup 2 Precision Filter 0.5μm 2 sets Mutual backup 3 First-stage nanofiltration <![CDATA[10m 3 / h, water production 75%, 15kW]]> 1 set 4 UV sterilizer Flow-through type, 1kW 1 set 5 storage tank <![CDATA[V=50m 3 Material: PE 3 sets Amino acid recovery unit 1 Concentrate reactor 3m³ / h, 5kW, material PP 1 set 2 bag filter 30μm 2 sets Mutual backup 3 Precision Filter 0.5μm 2 sets Mutual backup 4 Secondary nanofiltration <![CDATA[3m 3 / h, water production 60%, 10kW]]> 1 set The high-pressure pump uses a plunger pump. 5 Low-temperature evaporation crystallization Evaporation capacity 16t / d, 15kW, material 2205 1 set 6 storage tank <![CDATA[20m 3 Material: PE 2 sets

[0051] Example 1

[0052] A process for treating wastewater after enzyme desorption includes the following steps:

[0053] (1) Fatty acid recovery

[0054] Calcium chloride was added to the enzymatic desorption wastewater at a rate of 5 kg / t. After standing for 8 hours, solid-liquid separation was performed using a horizontal screw centrifuge to obtain a clear liquid and a water-containing solid with a water content of 86%. The water-containing solid was then pressed and dehydrated to obtain a fatty acid product with a water content of 55%.

[0055] (2) Brine recovery

[0056] The clear liquid described in step (1) is filtered and separated by passing it through a bag filter, a precision filter and a first-stage nanofiltration to obtain concentrated water a and permeate a. The permeate a is then sterilized by ultraviolet light and reused in the workshop.

[0057] (3) Amino acid recovery

[0058] Calcium chloride is added to the concentrated water a in step (2) at a rate of 1 kg / t. The mixture is filtered to obtain a precipitate and a filtrate. The precipitate is returned to the solid-liquid separation process for further processing. The filtrate is then subjected to a bag filter, a precision filter, and a secondary nanofiltration process for graded filtration to obtain concentrated water b and permeate b. Concentrated water b is placed in a low-temperature evaporation crystallization kettle with an internal spiral scraper for low-temperature evaporation at a temperature of 40°C for 8 hours to obtain condensate and amino acids containing salt. Both permeate b and condensate are sent to a wastewater treatment plant for wastewater treatment.

[0059] The processing results of each step in Example 1 are shown in Table 2.

[0060] Table 2

[0061] Serial Number Processing unit COD mg / L TN mg / L Conductivity μs / cm Remark 1 Enzymatic hydrolysis wastewater 39000 3600 66000 2 Clear liquid 21000 3000 70000 To first-stage nanofiltration 3 Through liquid a 2200 900 44000 Workshop reuse 4 Concentrate a 28000 3300 54000 To secondary nanofiltration 5 Concentrated water b 38000 4200 60000 Low-temperature evaporation 6 Through liquid b 3200 1100 44000 Go to sewage station 7 Condensate 350 190 400 Go to sewage station

[0062] As shown in Table 2, the wastewater treatment process provided by this invention recovers fatty acid products from wastewater through calcium chloride precipitation and pressing dehydration; and obtains salt-containing amino acid concentrates through nanofiltration, low-temperature evaporation and other processes, realizing the resource utilization of high-value organic matter in the enzymatically desorbed wastewater.

[0063] The water purification effect is excellent. Table 2 shows that the original wastewater had a COD as high as 39,000 mg / L, TN as high as 3,600 mg / L, and conductivity as high as 66,000 μS / cm. After treatment, the final condensate COD decreased to 350 mg / L, TN to 190 mg / L, and conductivity to only 400 μS / cm, with water quality approaching industrial water standards. This effectively reduced the treatment load on the wastewater treatment plant, while simultaneously expanding wastewater treatment capacity by approximately 50% while ensuring stable operation. The overall process achieves wastewater reduction and resource recovery, combining environmental benefits with significant economic benefits.

[0064] Example 2

[0065] A process for treating wastewater after enzyme desorption includes the following steps:

[0066] (1) Fatty acid recovery

[0067] Calcium chloride was added to the enzymatic desorption wastewater at a rate of 3 kg / t. After standing for 6 hours, solid-liquid separation was performed using a horizontal screw centrifuge to obtain a clear liquid and a water-containing solid with a water content of 75%. The water-containing solid was then pressed and dehydrated to obtain a fatty acid product with a water content of 50%.

[0068] (2) Brine recovery

[0069] The clear liquid described in step (1) is filtered and separated by passing it through a bag filter, a precision filter and a first-stage nanofiltration to obtain concentrated water a and permeate a. The permeate a is then sterilized by ultraviolet light and reused in the workshop.

[0070] (3) Amino acid recovery

[0071] Calcium chloride is added to the concentrated water a in step (2) at a rate of 0.5 kg / t. The mixture is filtered to obtain a precipitate and a filtrate. The precipitate is returned to the solid-liquid separation process for further processing. The filtrate is then subjected to a bag filter, a precision filter, and a secondary nanofiltration process for graded filtration to obtain concentrated water b and permeate b. Concentrated water b is placed in a low-temperature evaporation crystallization kettle with an internal spiral scraper for low-temperature evaporation at a temperature of 45°C for 10 hours to obtain condensate and amino acids containing salt. Both permeate b and condensate are sent to a wastewater treatment plant for wastewater treatment.

[0072] Example 3

[0073] A process for treating wastewater after enzyme desorption includes the following steps:

[0074] (1) Fatty acid recovery

[0075] Calcium chloride was added to the enzymatic desorption wastewater at a rate of 8 kg / t. After standing for 8 hours, solid-liquid separation was performed using a horizontal screw centrifuge to obtain a clear liquid and a water-containing solid with a water content of 80%. The water-containing solid was then pressed and dehydrated to obtain a fatty acid product with a water content of 52%.

[0076] (2) Brine recovery

[0077] The clear liquid described in step (1) is filtered and separated by passing it through a bag filter, a precision filter and a first-stage nanofiltration to obtain concentrated water a and permeate a. The permeate a is then sterilized by ultraviolet light and reused in the workshop.

[0078] (3) Amino acid recovery

[0079] Calcium chloride is added to the concentrated water a in step (2) at a rate of 3 kg / t. The mixture is filtered to obtain a precipitate and a filtrate. The precipitate is returned to the solid-liquid separation process for further processing. The filtrate is then subjected to a bag filter, a precision filter, and a secondary nanofiltration process for graded filtration to obtain concentrated water b and permeate b. Concentrated water b is placed in a low-temperature evaporation crystallization kettle with an internal spiral scraper for low-temperature evaporation at a temperature of 50°C for 8 hours to obtain condensate and salt-containing amino acids. Both permeate b and condensate are sent to a wastewater treatment plant for wastewater treatment.

[0080] Testing showed that the wastewater treatment effects of the wastewater treatment processes provided in Examples 2-3 were not significantly different from those in Example 1.

[0081] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A process for treating wastewater after enzyme desorption, characterized in that, Includes the following steps: (1) Fatty acid recovery Calcium chloride was added to the wastewater after enzyme desorption, and the mixture was allowed to stand for a period of time. Solid-liquid separation was then performed to obtain a clear liquid and a water-containing solid. The water-containing solid was then pressed and dehydrated to obtain fatty acids. (2) Brine recovery The clear liquid described in step (1) is filtered and separated to obtain concentrated water a and permeate a. The permeate a is sterilized and then reused in the workshop. (3) Amino acid recovery Calcium chloride is added to the concentrated water a in step (2), filtered, and precipitate and filtrate are obtained. The precipitate is returned to the solid-liquid separation process for further processing. The filtrate is subjected to graded filtration to obtain concentrated water b and permeate b. The concentrated water b is evaporated at low temperature to obtain condensate and salt-containing amino acids. Both permeate b and condensate are sent to the sewage treatment plant for sewage treatment.

2. The wastewater treatment process after enzyme desorption according to claim 1, characterized in that, The amount of calcium chloride added in step (1) is 3 kg / t-8 kg / t.

3. The wastewater treatment process after enzyme desorption according to claim 1, characterized in that, The resting time in step (1) is 6-12 hours.

4. The wastewater treatment process after enzyme desorption according to claim 1, characterized in that, The water content in the aqueous solid in step (1) is 75-88%, and the water content in the fatty acid is 50%-55%.

5. The wastewater treatment process after enzyme desorption according to claim 1, characterized in that, The filtration and separation steps in step (2) include: passing the clear liquid sequentially through a bag filter, a precision filter, and a primary nanofiltration process.

6. The wastewater treatment process after enzyme desorption according to claim 1, characterized in that, The sterilization in step (2) is carried out by ultraviolet sterilization, ozone oxidation, microfiltration or pasteurization.

7. The wastewater treatment process after enzyme desorption according to claim 1, characterized in that, The amount of calcium chloride added in step (3) is 0.5 kg / t to 3 kg / t.

8. The wastewater treatment process after enzyme desorption according to claim 1, characterized in that, The graded filtration process in step (3) is as follows: the filtrate is sequentially passed through a bag filter, a precision filter, and a secondary nanofiltration process.

9. The wastewater treatment process after enzyme desorption according to claim 1, characterized in that, The process parameters for low-temperature evaporation in step (3) are: temperature 40-50℃, time 8-10 hours.

10. The wastewater treatment process after enzyme desorption according to claim 1, characterized in that, The equipment for low-temperature evaporation in step (3) has a spiral scraper inside.