Biochemical excess sludge treatment agent, preparation method thereof and recycling method of biochemical excess sludge

Abstract

The invention relates to a biochemical excess sludge treatment agent, a preparation method thereof and a biochemical excess sludge recycling method, and the preparation method of the biochemical excess sludge treatment agent comprises the following steps: concentrating ammoximation wastewater to obtain a concentrated material; and adding a coagulant into the concentrated material for settling, and removing the sediment to obtain the biochemical residual sludge treatment agent. The ammoximation wastewater is concentrated and settled, the sediment is removed, the biochemical excess sludge treatment agent can be obtained, the biochemical excess sludge is treated by adopting the treatment agent, the yield of the biochemical excess sludge can be reduced from the source, and meanwhile resource utilization of the ammoximation wastewater is achieved.

Description

Technical Field

[0001] The present invention relates to a biochemical excess sludge treating agent and a preparation method thereof, and a method for recycling biochemical excess sludge. Background Art

[0002] Sewage treatment plants generally use activated sludge technology. In the process of treating sewage, a large amount of biochemical excess sludge is produced. Biochemical excess sludge contains a large number of toxic and harmful substances such as microorganisms, viruses, and parasites. Before being discharged into the environment, it needs to be reduced in volume to reduce pollution to the environment. At present, the general method of treating biochemical excess sludge is: concentration-conditioning-dehydration-export. The sludge transported out has a high moisture content (generally between 80 and 85%), a large volume of sludge, and a high content of viruses and bacteria, which increases the cost of subsequent disposal of sludge (such as landfill and incineration). How to reduce the output of biochemical excess sludge and solve the dilemma of biochemical excess sludge siege from the source is an urgent problem to be solved. Summary of the invention

[0003] The purpose of the present invention is to provide a biochemical excess sludge treatment agent and a preparation method thereof and a method for recycling biochemical excess sludge, so as to achieve source reduction of biochemical excess sludge.

[0004] In order to achieve the above-mentioned object, the present disclosure provides, in a first aspect, a method for preparing a biochemical excess sludge treatment agent, the method comprising:

[0005] Concentrating the ammoximation wastewater to obtain concentrated materials;

[0006] A coagulant is added to the concentrated material for sedimentation, and the sediment is removed to obtain a biochemical excess sludge treatment agent.

[0007] Optionally, the pH value of the ammoximation wastewater is 12-13.

[0008] Optionally, the concentration conditions include: a pressure of -0.06 MPa to -0.09 MPa, a temperature of 60 to 95° C., and a concentration multiple of 20 to 70 times, preferably 30 to 60 times.

[0009] Optionally, the sedimentation conditions include: pH value of 6 to 8, time of 15 to 120 min;

[0010] Preferably, the sedimentation conditions include: pH value of 6.5-7, and time of 30-60 minutes.

[0011] Optionally, based on the volume of the concentrated material, the amount of the coagulant is 20 to 80 mg / L, preferably 40 to 60 mg / L;

[0012] The coagulant is an aluminum salt, preferably, the aluminum salt is aluminum sulfate and / or aluminum chloride.

[0013] In a second aspect of the present disclosure, a biochemical excess sludge treatment agent prepared by the method described in the first aspect of the present disclosure is provided.

[0014] In a third aspect of the present disclosure, a method for recycling biochemical excess sludge is provided, the method comprising:

[0015] Under acidic conditions, the biochemical excess sludge is mixed with a treatment agent for treatment to obtain a treated material;

[0016] Wherein, the treatment agent is the biochemical excess sludge treatment agent described in the second aspect of the present disclosure.

[0017] Optionally, the biochemical excess sludge has a moisture content of 99.6-99.8% by weight, a total suspended solid content of 2000-3600 mg / L, and a volatile suspended matter content of 1300-2600 mg / L.

[0018] Optionally, the acidic conditions include: a pH value of 3 to 7, preferably 4.5 to 6.5.

[0019] Optionally, based on the volume of the biochemical excess sludge, the amount of the treatment agent is 3 to 10 mL / L, preferably 5 to 8 mL / L;

[0020] The treatment conditions include: temperature of 15 to 40°C and time of 30 to 120 minutes;

[0021] Preferably, the treatment conditions include: temperature of 20-30° C. and time of 60-90 min.

[0022] Optionally, the method also includes sending the treated material to a front-end sewage treatment device.

[0023] Through the above technical scheme, the present invention concentrates and settles the ammonia oxime wastewater, and removes the sediment to obtain a biochemical excess sludge treatment agent. The use of the treatment agent to treat biochemical excess sludge can reduce the output of biochemical excess sludge from the source, while realizing the resource utilization of the ammonia oxime wastewater.

[0024] Other features and advantages of the present disclosure will be described in detail in the following detailed description. DETAILED DESCRIPTION

[0025] The specific embodiments of the present disclosure are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present disclosure, and are not used to limit the present disclosure.

[0026] In a first aspect, the present disclosure provides a method for preparing a biochemical excess sludge treatment agent, the method comprising:

[0027] Concentrating the ammoximation wastewater to obtain concentrated materials;

[0028] A coagulant is added to the concentrated material for sedimentation, and the sediment is removed to obtain a biochemical excess sludge treatment agent.

[0029] According to the present disclosure, the ammoximation wastewater refers to the wastewater generated by the process of preparing cyclohexanone oxime from cyclohexanone in the caprolactam production process. The present disclosure has no special requirements on the components and properties of the ammoximation wastewater, and is widely applicable to various caprolactam production wastewaters. For example, the chemical oxygen demand (COD) of the ammoximation wastewater can be 2000-12000 mg / L, the ratio of 5-day biochemical oxygen demand to chemical oxygen demand (BOD5 / COD) can be 0-0.01, and the content of peroxide can be 6120 mg / L-9171 mg / L.

[0030] In a preferred embodiment, the pH value of the ammoximation wastewater is 12 to 13, and the treatment agent obtained by using alkaline ammoximation wastewater as a raw material is particularly suitable for treating biochemical excess sludge. At this time, the method may also include adjusting the pH value of the ammoximation wastewater to 12 to 13 using a pH regulator before concentrating. The pH regulator may be, for example, sodium hydroxide, potassium hydroxide, etc.

[0031] According to the present disclosure, the concentration can adopt the common means in the art for increasing the concentration of substances in wastewater, such as evaporation concentration. The concentration conditions enable the concentrated material to reach a suitable concentration level to avoid adverse effects on subsequent utilization due to excessive salt content in the wastewater. Specifically, the concentration conditions may include: a pressure of -0.06MPa to -0.09MPa, a temperature of 60 to 95°C, and a concentration multiple of 20 to 70 times, preferably 30 to 60 times. The concentrated material generally contains flocs, and there is no need to separate the concentrated material into solids and liquids, and the sedimentation is directly performed.

[0032] According to the present disclosure, the sedimentation conditions may include: pH value of 6 to 8, and time of 15 to 120 min. Preferably, the sedimentation conditions include: pH value of 6.5 to 7, and time of 30 to 60 min.

[0033] According to the present disclosure, based on the volume of the concentrated material, the amount of the coagulant can be 20 to 80 mg / L, preferably 40 to 60 mg / L. In one embodiment, the coagulant is an aluminum salt, and the use of aluminum salt as a coagulant does not introduce additional impurity ions and is conducive to improving the sedimentation effect; preferably, the aluminum salt is aluminum sulfate and / or aluminum chloride.

[0034] According to the present disclosure, the sediment is generally flocculent, and the clear liquid obtained after removing the sediment is the biochemical excess sludge treatment agent. Specifically, the method for removing the sediment can be, for example, filtration, centrifugation, etc.

[0035] In a second aspect of the present disclosure, a biochemical excess sludge treatment agent prepared by the method described in the first aspect of the present disclosure is provided.

[0036] According to the present disclosure, the properties of the biochemical excess sludge treatment agent may include: COD is 53140 mg / L to 132850 mg / L, and BOD5 / COD is 0 to 0.01.

[0037] In a third aspect of the present disclosure, a method for recycling biochemical excess sludge is provided, the method comprising: under acidic conditions, mixing the biochemical excess sludge with a treatment agent for treatment to obtain a treated material; wherein the treatment agent is the biochemical excess sludge treatment agent described in the second aspect of the present disclosure, thereby realizing the resource utilization of ammonia oxime wastewater.

[0038] According to the present disclosure, the biochemical excess sludge refers to solid, semi-solid and liquid wastes generated during sewage treatment, mainly generated by the sewage treatment system of a refinery, and is the activated sludge discharged from the system in a secondary sedimentation tank (or sedimentation area). The biochemical excess sludge has a higher COD and a lower BOD5 / COD. For example, the COD of the supernatant of the biochemical excess sludge can be 80 mg / L to 120 mg / L, the BOD5 / COD can be 0 to 0.04, and the pH value can be 6.8 to 7.3. The disclosed method is particularly suitable for biochemical excess sludge with a high water content that has not been pretreated by dehydration, etc. Specifically, the water content of the biochemical excess sludge is 99.6 to 99.8% by weight, the total suspended solids (SS) content is 2000 to 3600 mg / L, the volatile suspended solids (VSS) content is 1300 to 2600 mg / L, and the VSS / SS is 0.66 to 0.72% by weight. The treatment agent can be used to break up the bacterial flocs in the biochemical excess sludge and release the organic matter therein. The treated material has a reduced COD and a higher BOD5 / COD.

[0039] According to the present disclosure, the acidic conditions may include a pH value of 3 to 7, preferably 4.5 to 6.5.

[0040] According to the present disclosure, the treatment agent can achieve excellent treatment effects when used in a relatively small amount. Specifically, based on the volume of the biochemical excess sludge, the amount of the treatment agent can be 3 to 10 mL / L, preferably 5 to 8 mL / L.

[0041] The treatment can be performed under mild conditions. Specifically, the treatment conditions may include: a temperature of 15 to 40° C. and a time of 30 to 120 min; preferably, the treatment conditions include: a temperature of 20 to 30° C. and a time of 60 to 90 min.

[0042] According to the present disclosure, the treated material has good biodegradability and can be returned to the front-end sewage treatment device for sewage treatment without being discharged as sludge, thereby greatly reducing the output of biochemical excess sludge. Specifically, the COD of the supernatant of the treated material can be 1100mg / L~2100mg / L, and the BOD5 / COD can be 0.5~0.6. Furthermore, the method also includes sending the treated material to the front-end sewage treatment device, preferably adjusting the pH value of the treated material to 6.5~7.5 and then sending it to the front-end sewage treatment device. Among them, the front-end sewage treatment device refers to a device for treating industrial sewage and / or production sewage of a refinery enterprise, and the biochemical excess sludge is the back-end product of the front-end sewage treatment device.

[0043] The present invention concentrates and settles the ammonia oxime wastewater, and removes the sediment to obtain a biochemical excess sludge treatment agent. The treatment agent is used to treat the biochemical excess sludge, which can reduce the biochemical excess sludge output from the source and realize the resource utilization of the ammonia oxime wastewater.

[0044] The present disclosure is further illustrated by the following examples, but is not intended to limit the present disclosure.

[0045] In the following examples, the source of the ammoximation wastewater is wastewater taken from an industrial site, with a COD of 2625 mg / L, a BOD5 / COD of 0.01, and a peroxide content of 6171 mg / L.

[0046] Among them, COD analysis method: HJ 828-2017 Determination of chemical oxygen demand of water quality - dichromate method; BOD5 analysis method: HJ 505-2009 Determination of five-day biochemical oxygen demand (BOD5) of water quality - dilution and inoculation method.

[0047] Cell disruption rate = (1-sludge VSS after treatment / sludge VSS before treatment) × 100%

[0048] Examples 1 to 6 are used to illustrate the biochemical excess sludge treatment agent and the preparation method thereof disclosed in the present invention.

[0049] Example 1

[0050] Take 600mL of ammoximation wastewater, keep the pH value of the wastewater at 12, evaporate and concentrate at 95°C and a pressure of -0.08MPa. After concentrating 30 times, a concentrated material is obtained. An aluminum sulfate solution (concentration of 1000mg / L) is added to the concentrated material. Based on the volume of the concentrated material, an aluminum sulfate amount of 50mg / L is used. The solution is allowed to settle for 45min at a pH of 6.9, and the sediment is removed by filtration. The clear liquid is taken to obtain the treatment agent of this embodiment, which is designated as A1. Its COD is 76400mg / L and its BOD5 / COD is 0.

[0051] Example 2

[0052] Take 600mL of ammoximation wastewater, keep the pH value of the wastewater at 12, evaporate and concentrate at 90°C and a pressure of -0.09MPa. After concentrating 40 times, a concentrated material is obtained. An aluminum sulfate solution (concentration of 1000mg / L) is added to the concentrated material. Based on the volume of the concentrated material, an aluminum sulfate amount of 45mg / L is used. The solution is allowed to settle for 50min at a pH of 7, and the sediment is removed by filtration. The clear liquid is taken to obtain the treatment agent of this embodiment, which is calculated as A2. Its COD is 90400mg / L and BOD5 / COD is 0.

[0053] Example 3

[0054] Take 600mL of ammoximation wastewater, keep the pH value of the wastewater at 12, evaporate and concentrate at 85°C and a pressure of -0.09MPa. After concentrating 50 times, a concentrated material is obtained. An aluminum sulfate solution (concentration of 1000mg / L) is added to the concentrated material. Based on the volume of the concentrated material, an aluminum sulfate amount of 60mg / L is used. The solution is allowed to settle for 60min at a pH of 6.5. The sediment is removed by filtration, and the clear liquid is taken to obtain the treatment agent of this embodiment, which is calculated as A3. Its COD is 115000mg / L and BOD5 / COD is 0.

[0055] Example 4

[0056] Take 600mL of ammoximation wastewater, keep the pH value of the wastewater at 12, evaporate and concentrate at 95°C and a pressure of -0.08MPa. After concentrating 30 times, a concentrated material is obtained. An aluminum sulfate solution (concentration of 1000mg / L) is added to the concentrated material. Based on the volume of the concentrated material, an aluminum sulfate amount of 35mg / L is used. The solution is allowed to settle for 45min at a pH of 6.9, and the sediment is removed by filtration. The clear liquid is taken to obtain the treatment agent of this embodiment, which is calculated as A4, and its COD is 77200mg / L and BOD5 / COD is 0.

[0057] Example 5

[0058] Take 600mL of ammoximation wastewater, keep the pH value of the wastewater at 12, evaporate and concentrate at 95°C and a pressure of -0.08MPa. After concentrating 30 times, a concentrated material is obtained. An aluminum sulfate solution (concentration of 1000mg / L) is added to the concentrated material. Based on the volume of the concentrated material, an aluminum sulfate amount of 80mg / L is used. The solution is allowed to settle for 45min at a pH of 6.9, and the sediment is removed by filtration. The clear liquid is taken to obtain the treatment agent of this embodiment, which is designated as A5, and its COD is 75000mg / L and BOD5 / COD is 0.

[0059] Example 6

[0060] Take 600mL of ammoximation wastewater, keep the pH value of the wastewater at 11, evaporate and concentrate at 95°C and a pressure of -0.08MPa. After concentrating 30 times, a concentrated material is obtained. An aluminum sulfate solution (concentration of 1000mg / L) is added to the concentrated material. Based on the volume of the concentrated material, an aluminum sulfate amount of 50mg / L is used. The solution is allowed to settle for 45min at a pH of 6.9. The sediment is removed by filtration, and the clear liquid is taken to obtain the treatment agent of this embodiment, which is calculated as A6. Its COD is 75800g / L and BOD5 / COD is 0.

[0061] Comparative Example 1

[0062] Take 600mL of ammoximation wastewater, keep the pH value of the wastewater at 12, evaporate and concentrate at 95°C and a pressure of -0.08MPa. After concentrating 30 times, a concentrated material is obtained. The concentrated material is filtered to remove the floccules and then an aluminum sulfate solution (concentration of 1000mg / L) is added. Based on the volume of the filtered clear liquid, the amount of aluminum sulfate is 50mg / L. The solution is allowed to settle for 45min at a pH of 6.9, and the sediment is removed by filtration. The clear liquid is taken to obtain the treatment agent of this comparative example, calculated as B1, with a COD of 71100mg / L and a BOD5 / COD of 0.

[0063] Comparative Example 2

[0064] Take 600 mL of ammonia oxime wastewater, keep the pH value of the wastewater at 12, and evaporate and concentrate it at 95°C and a pressure of -0.08 MPa. After concentrating it 30 times, a concentrated material is obtained. After filtering the concentrated material to remove the flocs, the clear liquid is taken to obtain the treatment agent of this comparative example, calculated as B2, with a COD of 75800 mg / L and a BOD5 / COD of 0.

[0065] Comparative Example 3

[0066] In this comparative example, hydrogen peroxide with a concentration of 27 wt % is used as the treating agent, which is designated as B3.

[0067] Comparative Example 4

[0068] Take 600mL of ammoximation wastewater, keep the pH value of the wastewater at 12, do not concentrate, directly add aluminum sulfate solution (concentration of 1000mg / L), based on the volume of the wastewater, use 50mg / L of aluminum sulfate, and settle for 45min under the condition of pH 6.9. Filter to remove the sediment, and take the clear liquid to obtain the treatment agent of this comparative example, calculated as B4, whose COD is 2800mg / L and BOD5 / COD is 0.

[0069] Examples 7 to 15 are used to illustrate the method of treating biochemical excess sludge using the above-mentioned treatment agent.

[0070] In the following examples, the source of the biochemical excess sludge is the biochemical excess sludge produced in the secondary sedimentation tank of the sewage treatment device of the refinery enterprise, and its supernatant COD is 98 mg / L, BOD5 / COD is 0.02, pH value is 7.3, water content is 99.8% by weight, total suspended solids (SS) content is 2120 mg / L, volatile suspended solids (VSS) content is 1440 mg / L, and VSS / SS is 0.68% by weight.

[0071] Embodiments 7 to 12

[0072] The pH value of the biochemical excess sludge was adjusted to 5.5, and the above-mentioned treatment agents A1 to A6 were added for treatment. Based on the volume of the biochemical excess sludge, the amount of the treatment agent was 6 mL / L, the treatment temperature was 25°C, and the treatment time was 60 min. After the treatment was completed, the treated material was taken to test COD, BOD5 / COD and calculate the cell lysis rate. After the pH value was adjusted to 7.1, it could be sent back to the front-end sewage treatment device. The results are listed in Table 1.

[0073] Embodiment 13

[0074] The pH value of the biochemical excess sludge was adjusted to 5.5, and the above-mentioned treatment agent A1 was added for treatment. Based on the volume of the biochemical excess sludge, the amount of the treatment agent was 3 mL / L, the treatment temperature was 25°C, and the treatment time was 60 min. After the treatment was completed, the treated material was taken to test COD, BOD5 / COD and calculate the cell lysis rate. After the pH value was adjusted to 7.1, it could be sent back to the front-end sewage treatment device. The results are listed in Table 1.

[0075] Embodiment 14

[0076] The pH value of the biochemical excess sludge was adjusted to 5.5, and the above-mentioned treatment agent A1 was added for treatment. Based on the volume of the biochemical excess sludge, the amount of the treatment agent was 10 mL / L, the treatment temperature was 25°C, and the treatment time was 60 min. After the treatment was completed, the treated material was taken to test COD, BOD5 / COD and calculate the cell lysis rate. After the pH value was adjusted to 7.1, it could be sent back to the front-end sewage treatment device. The results are listed in Table 1.

[0077] Embodiment 15

[0078] The pH value of the biochemical excess sludge was adjusted to 3, and the above-mentioned treatment agent A1 was added for treatment. Based on the volume of the biochemical excess sludge, the amount of the treatment agent was 6 mL / L, the treatment temperature was 15°C, and the treatment time was 30 min. After the treatment was completed, the treated material was taken to test COD, BOD5 / COD and calculate the cell lysis rate. After the pH value was adjusted to 7.1, it could be sent back to the front-end sewage treatment device. The results are listed in Table 1.

[0079] Comparative Example 5

[0080] The pH value of the biochemical excess sludge was adjusted to 8, and the above-mentioned treatment agent A1 was added for treatment. Based on the volume of the biochemical excess sludge, the amount of the treatment agent was 6 mL / L, the treatment temperature was 40°C, and the treatment time was 120 min. After the treatment was completed, the treated material was taken to test COD, BOD5 / COD and calculate the cell lysis rate. After the pH value was adjusted to 7.1, it could be sent back to the front-end sewage treatment device. The results are listed in Table 1.

[0081] Comparative Examples 6 to 9

[0082] The pH value of the biochemical excess sludge was adjusted to 5.5, and the above-mentioned treatment agents B1 to B4 were added for treatment. Based on the volume of the biochemical excess sludge, the amount of the treatment agent was 6 mL / L, the treatment temperature was 25°C, and the treatment time was 60 min. After the treatment was completed, the treated material was taken to test COD, BOD5 / COD and calculate the cell disruption rate. The results are listed in Table 1.

[0083] Comparative Example 10

[0084] The pH value of the biochemical excess sludge was adjusted to 8, and the above-mentioned treatment agent B1 was added for treatment. Based on the volume of the biochemical excess sludge, the amount of the treatment agent was 6 mL / L, the treatment temperature was 25°C, and the treatment time was 60 min. After the treatment was completed, the treated material was taken to test COD, BOD5 / COD and calculate the cell disruption rate. The results are listed in Table 1.

[0085] Table 1

[0086]

[0087]

[0088] As can be seen from Table 1, the treatment agent disclosed in the present invention is used to treat biochemical excess sludge, and the sludge breakdown efficiency is high and the biodegradability is good. The treated material can be returned to the front-end sewage treatment, thereby reducing the output of biochemical excess sludge from the source.

[0089] The preferred embodiments of the present disclosure are described in detail above; however, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0090] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0091] In addition, various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A method for preparing a biochemical excess sludge treatment agent, characterized in that: The method includes: Concentrating the ammoximation wastewater to obtain concentrated materials; A coagulant is added to the concentrated material for sedimentation, and the sediment is removed to obtain a biochemical excess sludge treatment agent.

2. The method according to claim 1, wherein: The pH value of the ammoximation wastewater is 12-13.

3. The method according to claim 1, wherein: The concentration conditions include: a pressure of -0.06 MPa to -0.09 MPa, a temperature of 60 to 95° C., and a concentration multiple of 20 to 70 times, preferably 30 to 60 times.

4. The method according to claim 1, wherein: The sedimentation conditions include: pH value of 6 to 8, time of 15 to 120 minutes; Preferably, the sedimentation conditions include: pH value of 6.5-7, and time of 30-60 minutes.

5. The method according to claim 1, wherein: Based on the volume of the concentrated material, the dosage of the coagulant is 20 to 80 mg / L, preferably 40 to 60 mg / L; The coagulant is an aluminum salt, preferably, the aluminum salt is aluminum sulfate and / or aluminum chloride.

6. A biochemical excess sludge treating agent prepared by the method according to any one of claims 1 to 5.

7. A method for recycling biochemical excess sludge, characterized in that: The method includes: Under acidic conditions, the biochemical excess sludge is mixed with a treatment agent for treatment to obtain a treated material; Wherein, the treatment agent is the biochemical excess sludge treatment agent as described in claim 6.

8. The method according to claim 7, wherein: The water content of the biochemical excess sludge is 99.6-99.8% by weight, the total solid suspended matter content is 2000-3600 mg / L, and the volatile suspended matter content is 1300-2600 mg / L.

9. The method according to claim 7, wherein: The acidic conditions include: a pH value of 3 to 7, preferably 4.5 to 6.

5.

10. The method according to claim 7, wherein: Based on the volume of the biochemical excess sludge, the dosage of the treatment agent is 3 to 10 mL / L, preferably 5 to 8 mL / L; The treatment conditions include: temperature of 15 to 40°C and time of 30 to 120 minutes; Preferably, the treatment conditions include: a temperature of 20 to 30° C. and a time of 60 to 90 min.

11. The method according to claim 7, wherein: The method also includes sending the treated material to a front-end sewage treatment device.

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