Biochemical residual sludge treatment agent, method for preparing the same, and method for recycling biochemical residual sludge

Abstract

The present disclosure relates to a biochemical residual sludge treatment agent, a preparation method thereof and a biochemical residual sludge recycling method. The preparation method of the biochemical residual sludge treatment agent comprises: concentrating an ammoxilation wastewater to obtain a concentrated material; adding a coagulant to the concentrated material to perform sedimentation, removing the sediment to obtain the biochemical residual sludge treatment agent. The present disclosure can obtain the biochemical residual sludge treatment agent by concentrating and sedimenting the ammoxilation wastewater and removing the sediment. The biochemical residual sludge yield can be reduced from the source by using the treatment agent to treat the biochemical residual sludge, and the resource utilization of the ammoxilation wastewater can be realized.

Description

Technical Field

[0001] This disclosure relates to a biochemical waste sludge treatment agent, its preparation method, and a method for reusing biochemical waste sludge. Background Technology

[0002] Wastewater treatment plants commonly employ activated sludge processes, generating substantial amounts of residual biochemical sludge during treatment. This sludge contains numerous microorganisms, viruses, parasites, and other toxic and harmful substances, requiring volume reduction treatment before release into the environment to minimize pollution. Currently, the general method for treating residual biochemical sludge is: concentration—conditioning—dewatering—transportation. The transported sludge has a high moisture content (typically between 80-85%), is bulky, and contains high levels of viruses and bacteria, increasing the costs of subsequent disposal (such as landfill or incineration). Therefore, reducing the production of residual biochemical sludge and addressing the problem at its source is an urgent issue that needs to be resolved. Summary of the Invention

[0003] The purpose of this disclosure is to provide a biochemical waste sludge treatment agent, its preparation method, and a method for reusing biochemical waste sludge, so as to achieve source reduction of biochemical waste sludge.

[0004] To achieve the above objectives, in a first aspect, this disclosure provides a method for preparing a biochemical waste sludge treatment agent, the method comprising:

[0005] The ammonia oxime wastewater was concentrated to obtain the concentrated material.

[0006] A coagulant is added to the concentrated material to allow it to settle, and the sediment is removed to obtain a biochemical waste sludge treatment agent.

[0007] Optionally, the pH value of the ammonia oxime 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 factor of 20 to 70 times, preferably 30 to 60 times.

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

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

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

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

[0013] In a second aspect, this disclosure provides a biochemical waste sludge treatment agent prepared by the method described in the first aspect of this disclosure.

[0014] A third aspect of this disclosure provides a method for reusing waste biochemical sludge, the method comprising:

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

[0016] The treatment agent is the biochemical waste sludge treatment agent described in the second aspect of this disclosure.

[0017] Optionally, the moisture content of the biochemical waste sludge is 99.6-99.8% by weight, the total suspended solids content is 2000-3600 mg / L, and the volatile suspended solids content is 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 residual biochemical sludge, the dosage of the treatment agent is 3-10 mL / L, preferably 5-8 mL / L;

[0020] The processing conditions include: a temperature of 15–40°C and a time of 30–120 min;

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

[0022] Optionally, the method further includes feeding the treated material into a front-end wastewater treatment device.

[0023] Through the above technical solution, this disclosure concentrates and settles ammonia oxime wastewater, and removes the sediment to obtain a biochemical waste sludge treatment agent. Using this treatment agent to treat biochemical waste sludge can reduce the production of biochemical waste sludge from the source, and at the same time realize the resource utilization of ammonia oxime wastewater.

[0024] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Detailed Implementation

[0025] The following provides a detailed description of specific embodiments of this disclosure. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit this disclosure.

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

[0027] The ammonia oxime wastewater was concentrated to obtain the concentrated material.

[0028] A coagulant is added to the concentrated material to allow it to settle, and the sediment is removed to obtain a biochemical waste sludge treatment agent.

[0029] According to this disclosure, the ammonia oxime wastewater refers to the wastewater generated in the process of producing cyclohexanone oxime from cyclohexanone in the caprolactam production process. This disclosure does not impose special requirements on the composition or properties of the ammonia oxime wastewater and is widely applicable to various caprolactam production wastewaters. For example, the chemical oxygen demand (COD) of the ammonia oxime wastewater can be 2000–12000 mg / L, the 5-day biochemical oxygen demand to chemical oxygen demand ratio (BOD5 / COD) can be 0–0.01, and the peroxide content can be 6120 mg / L–9171 mg / L.

[0030] In a preferred embodiment, the pH value of the ammonia oxime wastewater is 12-13. Treatment agents obtained using alkaline ammonia oxime wastewater as raw material are particularly suitable for treating residual biochemical sludge. In this case, the method may further include adjusting the pH value of the ammonia oxime wastewater to 12-13 using a pH adjuster before concentration. The pH adjuster may be, for example, sodium hydroxide, potassium hydroxide, etc.

[0031] According to this disclosure, the concentration can employ methods commonly used in the art to increase the concentration of substances in wastewater, such as evaporation concentration. The concentration conditions ensure that the concentrated material reaches a suitable degree of concentration, avoiding adverse effects on subsequent utilization due to excessively high salt content in the wastewater. Specifically, the concentration conditions may include: a pressure of -0.06 MPa to -0.09 MPa, a temperature of 60–95°C, and a concentration factor of 20–70 times, preferably 30–60 times. The resulting concentrated material generally contains flocculent matter, eliminating the need for solid-liquid separation and allowing direct sedimentation.

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

[0033] According to this disclosure, based on the volume of the concentrated material, the dosage of the coagulant can be 20-80 mg / L, preferably 40-60 mg / L. In one embodiment, the coagulant is an aluminum salt. Using aluminum salt as a coagulant does not introduce additional impurities and is beneficial for improving sedimentation. Preferably, the aluminum salt is aluminum sulfate and / or aluminum chloride.

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

[0035] In a second aspect, this disclosure provides a biochemical waste sludge treatment agent prepared by the method described in the first aspect of this disclosure.

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

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

[0038] According to this disclosure, the biochemical waste sludge refers to solid, semi-solid, and liquid waste generated during wastewater treatment, mainly produced by the wastewater treatment system of refining and chemical enterprises, and discharged from the system in the secondary sedimentation tank (or sedimentation zone). The biochemical waste sludge has a high COD and a low BOD5 / COD ratio. For example, the COD of the supernatant of the biochemical waste sludge can be 80 mg / L to 120 mg / L, the BOD5 / COD ratio can be 0 to 0.04, and the pH value can be 6.8 to 7.3. The method of this disclosure is particularly suitable for biochemical waste sludge with a high water content that has not undergone pretreatment such as dewatering. Specifically, the water content of the biochemical waste 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 ratio is 0.66 to 0.72% by weight. This treatment agent can break down the flocs in the residual biochemical sludge, releasing the organic matter therein. The treated material has reduced COD and higher BOD5 / COD.

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

[0040] According to this disclosure, the treatment agent can achieve excellent treatment results with a small dosage. Specifically, based on the volume of the residual biochemical sludge, the dosage of the treatment agent can be 3-10 mL / L, preferably 5-8 mL / L.

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

[0042] According to this disclosure, the treated material has good biodegradability and can be returned to the upstream wastewater treatment unit for wastewater treatment without being discharged as sludge, thereby greatly reducing the production of residual biochemical sludge. Specifically, the COD of the supernatant of the treated material can be 1100 mg / L to 2100 mg / L, and the BOD5 / COD ratio can be 0.5 to 0.6. Further, the method includes sending the treated material into the upstream wastewater treatment unit, preferably adjusting the pH of the treated material to 6.5 to 7.5 before sending it into the upstream wastewater treatment unit. The upstream wastewater treatment unit refers to a device used to treat industrial wastewater and / or production wastewater from refining and chemical enterprises, and the residual biochemical sludge is a downstream product of this upstream wastewater treatment unit.

[0043] This disclosure describes a method for concentrating and settling ammonia oxime wastewater, and removing the settling material to obtain a biochemical waste sludge treatment agent. Using this agent to treat biochemical waste sludge can reduce the production of biochemical waste sludge at the source, while simultaneously realizing the resource utilization of 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 ammonia oxime wastewater was wastewater taken from the industrial site, with a COD of 2625 mg / L, a BOD5 / COD ratio of 0.01, and a peroxide content of 6171 mg / L.

[0046] Among them, the COD analysis method is: HJ 828-2017 Determination of Chemical Oxygen Demand in Water - Dichromate Method; the BOD5 analysis method is: HJ 505-2009 Determination of Five-Day Biochemical Oxygen Demand (BOD5) in Water - Dilution and Inoculation Method.

[0047] Cell dissociation rate = (1 - VSS of treated sludge / VSS of untreated sludge) × 100%

[0048] Examples 1-6 illustrate the biochemical waste sludge treatment agent and its preparation method disclosed herein.

[0049] Example 1

[0050] Take 600 mL of ammonia oxime wastewater, maintain the pH value of the wastewater at 12, and evaporate and concentrate it at 95℃ and -0.08 MPa. After concentrating it 30 times, the concentrated material is obtained. Add aluminum sulfate solution (concentration of 1000 mg / L) to the concentrated material. Based on the volume of the concentrated material, the amount of aluminum sulfate is 50 mg / L. Settle at pH 6.9 for 45 min. Filter to remove the precipitate and take the clear liquid to obtain the treatment agent of this embodiment, which is designated as A1. Its COD is 76400 mg / L and BOD5 / COD is 0.

[0051] Example 2

[0052] Take 600 mL of ammonia oxime wastewater, maintain the pH value of the wastewater at 12, and evaporate and concentrate it at 90℃ and -0.09 MPa. After 40 times concentration, the concentrated material is obtained. Add aluminum sulfate solution (concentration of 1000 mg / L) to the concentrated material. Based on the volume of the concentrated material, the amount of aluminum sulfate is 45 mg / L. Settle for 50 min at pH 7. Filter to remove the precipitate and take the clear liquid to obtain the treatment agent of this embodiment, which is designated as A2. Its COD is 90400 mg / L and BOD5 / COD is 0.

[0053] Example 3

[0054] Take 600 mL of ammonia oxime wastewater, maintain the pH value of the wastewater at 12, and evaporate and concentrate it at 85℃ and -0.09 MPa. After concentrating it 50 times, the concentrated material is obtained. Add aluminum sulfate solution (concentration of 1000 mg / L) to the concentrated material. Based on the volume of the concentrated material, the amount of aluminum sulfate is 60 mg / L. Allow it to settle for 60 min at a pH value of 6.5. Filter to remove the precipitate and take the clear liquid to obtain the treatment agent of this embodiment, which is designated as A3. Its COD is 115000 mg / L and BOD5 / COD is 0.

[0055] Example 4

[0056] Take 600 mL of ammonia oxime wastewater, maintain the pH value of the wastewater at 12, and evaporate and concentrate it at 95℃ and -0.08 MPa. After concentrating it 30 times, the concentrated material is obtained. Add aluminum sulfate solution (concentration of 1000 mg / L) to the concentrated material. Based on the volume of the concentrated material, the amount of aluminum sulfate is 35 mg / L. Settle at pH 6.9 for 45 min. Filter to remove the precipitate and take the clear liquid to obtain the treatment agent of this embodiment, which is designated as A4. Its COD is 77200 mg / L and BOD5 / COD is 0.

[0057] Example 5

[0058] Take 600 mL of ammonia oxime wastewater, maintain the pH value of the wastewater at 12, and evaporate and concentrate it at 95℃ and -0.08 MPa. After concentrating it 30 times, the concentrated material is obtained. Add aluminum sulfate solution (concentration of 1000 mg / L) to the concentrated material. Based on the volume of the concentrated material, the amount of aluminum sulfate is 80 mg / L. Settle at pH 6.9 for 45 min. Filter to remove the precipitate, and take the clear liquid to obtain the treatment agent of this embodiment, which is designated as A5. Its COD is 75000 mg / L and BOD5 / COD is 0.

[0059] Example 6

[0060] Take 600 mL of ammonia oxime wastewater, maintain the pH value of the wastewater at 11, and evaporate and concentrate it at 95℃ and -0.08 MPa. After concentrating it 30 times, the concentrated material is obtained. Add aluminum sulfate solution (concentration of 1000 mg / L) to the concentrated material. Based on the volume of the concentrated material, the amount of aluminum sulfate is 50 mg / L. Settle at pH 6.9 for 45 min. Filter to remove the precipitate and take the clear liquid to obtain the treatment agent of this embodiment, which is designated as A6. Its COD is 75800 g / L and BOD5 / COD is 0.

[0061] Comparative Example 1

[0062] Take 600 mL of ammonia oxime wastewater, maintain the pH value of the wastewater at 12, and evaporate and concentrate it at 95℃ and -0.08 MPa. After concentrating it 30 times, the concentrated material is obtained. Filter the concentrated material to remove flocculent matter, and then add aluminum sulfate solution (concentration of 1000 mg / L). Based on the volume of the filtered clear liquid, the amount of aluminum sulfate is 50 mg / L. Settle at pH 6.9 for 45 min, filter to remove the precipitate, and take the clear liquid to obtain the treatment agent of this comparative example, labeled as B1, with a COD of 71100 mg / L and a BOD5 / COD ratio of 0.

[0063] Comparative Example 2

[0064] Take 600 mL of ammonia oxime wastewater, maintain the pH value of the wastewater at 12, and evaporate and concentrate it at 95℃ and -0.08 MPa. After concentrating it 30 times, the concentrated material is obtained. After filtering the concentrated material to remove flocculent matter, the clear liquid is taken to obtain the treatment agent of this comparative example, which is designated as B2. Its COD is 75800 mg / L and BOD5 / COD is 0.

[0065] Comparative Example 3

[0066] This comparative example uses hydrogen peroxide at a concentration of 27% by weight as the treatment agent, denoted as B3.

[0067] Comparative Example 4

[0068] Take 600 mL of ammonia oxime wastewater, maintain the pH of the wastewater at 12, do not concentrate, and directly add aluminum sulfate solution (concentration of 1000 mg / L). Based on the volume of wastewater, the amount of aluminum sulfate used is 50 mg / L. Allow the mixture to settle for 45 min at a pH of 6.9, filter to remove the precipitate, and take the clear liquid to obtain the treatment agent of this comparative example, labeled as B4, with a COD of 2800 mg / L and a BOD5 / COD ratio of 0.

[0069] Examples 7-15 illustrate the method of treating biochemical waste sludge using the above-mentioned treatment agents.

[0070] In the following embodiments, the source of the biochemical waste sludge is the biochemical waste sludge generated from the secondary sedimentation tank of the wastewater treatment unit of the refining and chemical enterprise. Its supernatant has a COD of 98 mg / L, a BOD5 / COD ratio of 0.02, a pH of 7.3, a water content of 99.8% by weight, a total suspended solids (SS) content of 2120 mg / L, a volatile suspended solids (VSS) content of 1440 mg / L, and a VSS / SS ratio of 0.68% by weight.

[0071] Examples 7-12

[0072] The pH of the residual biological sludge was adjusted to 5.5, and treatment agents A1 to A6 were added respectively for treatment. The dosage of the treatment agent was 6 mL / L, based on the volume of the residual biological sludge. The treatment temperature was 25℃, and the treatment time was 60 min. After treatment, the treated material was tested for COD and BOD5 / COD, and the cell breakdown rate was calculated. After adjusting the pH to 7.1, the material could be returned to the upstream wastewater treatment unit. The results are listed in Table 1.

[0073] Example 13

[0074] The pH of the residual biological sludge was adjusted to 5.5, and treatment agent A1 was added for treatment. The agent dosage was 3 mL / L based on the volume of the residual biological sludge, the treatment temperature was 25℃, and the treatment time was 60 min. After treatment, the treated material was tested for COD and BOD5 / COD, and the cell breakdown rate was calculated. After adjusting the pH to 7.1, the material could be returned to the upstream wastewater treatment unit. The results are listed in Table 1.

[0075] Example 14

[0076] The pH of the residual biological sludge was adjusted to 5.5, and treatment agent A1 was added for treatment. The agent concentration was 10 mL / L, based on the volume of the residual biological sludge. The treatment temperature was 25℃, and the treatment time was 60 min. After treatment, the treated material was tested for COD and BOD5 / COD, and the cell breakdown rate was calculated. After adjusting the pH to 7.1, the material could be returned to the upstream wastewater treatment unit. The results are listed in Table 1.

[0077] Example 15

[0078] The pH of the residual biological sludge was adjusted to 3, and the above-mentioned treatment agent A1 was added for treatment. Based on the volume of the residual biological sludge, the dosage of the treatment agent was 6 mL / L, the treatment temperature was 15℃, and the treatment time was 30 min. After treatment, the treated material was tested for COD and BOD5 / COD, and the cell breakdown rate was calculated. After adjusting the pH to 7.1, the material could be returned to the upstream wastewater treatment unit. The results are listed in Table 1.

[0079] Comparative Example 5

[0080] The pH of the residual biological sludge was adjusted to 8, and the above-mentioned treatment agent A1 was added for treatment. Based on the volume of the residual biological sludge, the dosage of the treatment agent was 6 mL / L, the treatment temperature was 40℃, and the treatment time was 120 min. After treatment, the treated material was tested for COD and BOD5 / COD, and the cell breakdown rate was calculated. After adjusting the pH to 7.1, the material could be returned to the upstream wastewater treatment unit. The results are listed in Table 1.

[0081] Comparative Examples 6–9

[0082] The pH of the waste biochemical sludge was adjusted to 5.5, and treatment agents B1 to B4 were added respectively for treatment. Based on the volume of waste biochemical sludge, the dosage of the treatment agent was 6 mL / L, the treatment temperature was 25℃, and the time was 60 min. After treatment, the COD and BOD5 / COD of the treated material were measured, and the cell dissociation rate was calculated. The results are listed in Table 1.

[0083] Comparative Example 10

[0084] The pH of the waste biochemical sludge was adjusted to 8, and the above-mentioned treatment agent B1 was added for treatment. Based on the volume of the waste biochemical sludge, the dosage of the treatment agent was 6 mL / L, the treatment temperature was 25℃, and the time was 60 min. After treatment, the COD and BOD5 / COD of the treated material were measured, and the cell dissociation rate was calculated. The results are listed in Table 1.

[0085] Table 1

[0086]

[0087]

[0088] As shown in Table 1, the treatment agent disclosed in this invention has high sludge breaking efficiency and good biodegradability. The treated material can be returned to the front-end wastewater treatment, reducing the production of biochemical waste sludge from the source.

[0089] The preferred embodiments of this disclosure have been described in detail above. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this 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, this disclosure will not describe the various possible combinations separately.

[0091] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A method for reusing waste biochemical sludge, characterized in that, The method includes: Under acidic conditions, the residual biochemical sludge is mixed with a treatment agent for treatment to obtain the treated material; wherein the residual biochemical sludge has a water content of 99.6~99.8% by weight, a total suspended solids content of 2000~3600 mg / L, and a volatile suspended solids content of 1300~2600 mg / L; The preparation method of the treatment agent includes: The ammonia oxime wastewater is concentrated to obtain a concentrated material; the pH value of the ammonia oxime wastewater is 12~13, and the peroxide content is 6120mg / L~9171mg / L; the concentration conditions include: pressure of -0.06MPa to -0.09MPa, temperature of 60~95℃, and concentration ratio of 20~70 times. A coagulant is added to the concentrated material to allow it to settle, and the sediment is removed to obtain the treatment agent.

2. The method according to claim 1, wherein, The concentration conditions include a concentration factor of 30 to 60 times.

3. The method according to claim 1, wherein, The sedimentation conditions include: pH value of 6-8 and time of 15-120 min.

4. The method according to claim 3, wherein, The sedimentation conditions include a pH value of 6.5-7 and a 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 20~80 mg / L; The coagulant is an aluminum salt.

6. The method according to claim 5, wherein, Based on the volume of the concentrated material, the dosage of the coagulant is 40~60 mg / L; The aluminum salt is aluminum sulfate and / or aluminum chloride.

7. The method according to claim 1, wherein, The acidic conditions include a pH value of 3 to 7.

8. The method according to claim 7, wherein, The acidic conditions include a pH value of 4.5 to 6.

5.

9. The method according to claim 1, wherein, Based on the volume of the residual biochemical sludge, the dosage of the treatment agent is 3~10mL / L; The processing conditions include a temperature of 15~40℃ and a time of 30~120min.

10. The method according to claim 9, wherein, Based on the volume of the residual biochemical sludge, the dosage of the treatment agent is 5~8 mL / L; The processing conditions include a temperature of 20-30°C and a time of 60-90 minutes.

11. The method according to claim 1, wherein, The method also includes sending the treated material into a front-end wastewater treatment device.

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