Method for treating domestic sewage by using high ferric salt coupling polyaluminum chloride reinforced high-speed contact stabilization process

Abstract

The application discloses a method for treating domestic sewage by using a high ferric salt coupling polyaluminum chloride reinforced high-speed contact stabilization process, and aims at solving problems of high sludge yield and low pollutant removal rate of the activated sludge method.The method for treating domestic sewage comprises the following steps: firstly, adding high ferric salt into domestic sewage and stirring to dissolve the high ferric salt to form iron (hydrogen) oxide particles; secondly, continuously adding polyaluminum chloride into the domestic sewage, and performing static precipitation after coagulation treatment; and thirdly, pumping the supernatant after precipitation into a high-speed contact stabilization reactor, inoculating the high-speed contact stabilization reactor with activated sludge in advance, and removing pollutants in the domestic sewage by biological adsorption or capture.The method promotes flocculation by using high ferric salt coupling polyaluminum chloride, and strengthens the effect of the high-speed contact stabilization process on removal of COD and PO4 3‑ -P in domestic sewage, and the removal rates of COD and PO4 3‑ -P in the domestic sewage can reach 90% and 100% respectively.

Description

Technical Field

[0001] This invention belongs to the field of wastewater biological treatment technology, specifically relating to a high-speed contact stabilization process enhanced by ferrate coupled with polyaluminum chloride to remove COD and PO4 from domestic sewage. 3- -P method. Background Technology

[0002] In recent years, to further improve carbon recovery efficiency, a high-speed contact stabilization system (HRCS) process with high sludge specific loading rate and low sludge retention time has been proposed. This process combines the advantages of high-speed activated sludge processes and contact stabilization processes, resulting in higher biosorption performance and the ability to recover more chemical energy from organic matter in wastewater. However, phosphorus removal remains a significant challenge for the practical application of this process. Existing studies have shown that adding ferric chloride (FeCl3) and polyaluminum chloride to the HRCS system can simultaneously remove organic carbon and phosphates from simulated wastewater within a single treatment unit.

[0003] The iron (hydrogen) oxide particles generated in situ after the self-decomposition of ferrates can adsorb heavy metals, NOM, and even TOC and COD. Furthermore, the flocs produced by ferrates have a different composition than FeCl3, making them an excellent coagulant. The synergistic potential for pollutant removal by ferrates and metal salt coagulants (such as polyaluminum chloride) has been observed by numerous researchers. Previous studies have demonstrated that combining ferrates with polyaluminum chloride can significantly improve the removal efficiency of organic pollutants. Summary of the Invention

[0004] The purpose of this invention is to address the problems of high energy consumption, high sludge production, high carbon emissions, and low pollutant removal rate in activated sludge processes, and to provide a method for treating domestic sewage using a high-speed contact stabilization process enhanced by coupling high-ferrate with polyaluminum chloride.

[0005] The present invention utilizes a high-speed contact stabilization process enhanced by coupling ferrate with polyaluminum chloride to treat domestic sewage, and is implemented according to the following steps:

[0006] 1. Add ferrate to domestic sewage and stir to dissolve the ferrate to form iron (hydrogen) oxide particles;

[0007] 2. Continue to add polyaluminum chloride to the domestic sewage that has already been treated with ferrate, and allow it to settle after coagulation treatment.

[0008] 3. The settled supernatant is pumped into a high-speed contact stabilization reactor using a peristaltic pump. The high-speed contact stabilization reactor is pre-inoculated with activated sludge to bio-adsorb or capture COD and PO4 from domestic sewage. 3- -P, thus completing the treatment of domestic sewage.

[0009] The present invention provides a method for treating domestic sewage using a high-speed contact stabilization process enhanced by coupling ferrate with polyaluminum chloride, which has the following beneficial effects:

[0010] (1) Ferrate is a green and environmentally friendly oxidant. After the reaction, the iron (hydrogen) oxide particles formed are non-toxic and have a good flocculation effect.

[0011] (2) After adding ferrate and polyaluminum chloride, due to the electron neutralization effect of iron oxide (hydrogen) and aluminum hydroxide, the hydrolysate of these two chemicals will agglomerate together to form large flocs, which can enhance the adsorption of organic matter. The organic pollutants in the wastewater are adsorbed on the hydrolysis products of iron and aluminum coagulants, forming colloidal or subcolloidal particles that are difficult to settle and remove. Then, they enter the high-speed contact stabilization process. The activated sludge efficiently captures the above substances through bioflocculation, thereby improving the organic matter capture efficiency.

[0012] (3) It reduces the energy consumption of aeration equipment in existing processes and has the characteristics of energy saving and consumption reduction;

[0013] (4) The experimental apparatus is simple in structure, easy to operate, low in cost and excellent in effect;

[0014] (5) Using the method of this invention to process COD and PO4 3- The removal rates of -P can reach over 90% and 100%, respectively. Among them, the removal of COD relies more on adsorption than microbial degradation, with adsorption accounting for over 85%. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the experimental apparatus for treating domestic sewage using a high-speed contact stabilization process enhanced by coupling high-ferrate with polyaluminum chloride in Example 1. In the diagram: 1-water tank, 2-stirrer, 3-inlet peristaltic pump, 4-sludge discharge port, 5-aeration pump, 6-gas flow meter, 7-sequencing batch reactor, 8-outlet, 9-outlet tank, 10-automatic control equipment. Detailed Implementation

[0016] Specific Implementation Method 1: This implementation method for treating domestic sewage using a high-speed contact stabilization process enhanced by coupling ferrate with polyaluminum chloride is carried out according to the following steps:

[0017] 1. Add ferrate to domestic sewage and stir to dissolve the ferrate to form iron (hydrogen) oxide particles;

[0018] 2. Continue to add polyaluminum chloride to the domestic sewage that has already been treated with ferrate, and allow it to settle after coagulation treatment.

[0019] 3. The settled supernatant is pumped into a high-speed contact stabilization reactor using a peristaltic pump. The high-speed contact stabilization reactor is pre-inoculated with activated sludge to bio-adsorb or capture COD and PO4 from domestic sewage. 3- -P, thus completing the treatment of domestic sewage.

[0020] This embodiment utilizes ferrate coupled with polyaluminum chloride to enhance the high-speed contact stabilization process for COD and PO4 in domestic sewage. 3- -P is used for capture and adsorption.

[0021] This embodiment utilizes ferrate coupled with polyaluminum chloride to promote flocculation and enhance the removal of COD and PO4 from domestic sewage by a high-speed contact stabilization process. 3- -P can reduce COD and PO4 in wastewater. 3- The removal rates of -P reached 90% and 100%, respectively.

[0022] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the concentration of ferrate added in step one is 5-30 mg / L.

[0023] Specific Implementation Method 3: This implementation method differs from Specific Implementation Method 1 or 2 in that in step 1, the stirring process is carried out at a stirring speed of 500-1000 r / min for 5-20 minutes.

[0024] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the mass ratio of polyaluminum chloride to ferrate added is 1:1 to 3:1.

[0025] Specific Implementation Method 5: This implementation method differs from Specific Implementation Methods 1 to 4 in that the coagulation process described in step 2 involves first reacting rapidly at a stirring speed of 400-800 r / min for 1-3 minutes, and then reacting slowly at a stirring speed of 10-60 r / min for 15-45 minutes.

[0026] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that the settling time in step two is 15 to 45 minutes.

[0027] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that the high-speed contact stabilization reactor described in step three is a cylindrical sequencing batch reactor, and the height-to-diameter ratio (H / D) of the high-speed contact stabilization reactor is 8 to 12.

[0028] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that the concentration of activated sludge inoculated in the high-speed contact stabilizing reactor in step three is 2000-4000 mg / L.

[0029] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that the operation mode of the high-speed contact stabilization reactor in step three is carried out in the order of water inlet - contact - micro-aeration stabilization - sedimentation - drainage. The water inlet stage lasts for 3 to 8 minutes, the contact stage lasts for 10 to 20 minutes, the micro-aeration stabilization stage lasts for 27 to 66 minutes, the sedimentation stage lasts for 40 to 60 minutes, the drainage stage lasts for 1 to 5 minutes, the volume exchange ratio is 30 to 70%, and the sludge retention time (SRT) is controlled at 1 to 5 days.

[0030] In this embodiment, the high-speed contact stabilization reactor is operated in the following sequence: water inlet - contact - micro-aeration stabilization - sedimentation - drainage, with each cycle lasting 2 hours.

[0031] Specific Implementation Method 10: This implementation method differs from Specific Implementation Method 9 in that the apparent gas flow rate of micro-aeration during the micro-aeration stabilization stage of the high-speed contact stabilizing reactor operation in step 3 is 0.1-0.2 cm / s.

[0032] Example 1: This example describes a method for treating domestic wastewater using a high-speed contact stabilization process enhanced by coupling ferrate with polyaluminum chloride, implemented according to the following steps:

[0033] 1. Add 10 mg / L of ferrate to domestic sewage and stir rapidly at 800 r / min for 15 min to dissolve the ferrate and form iron (hydrogen) oxide particles.

[0034] 2. Add 20 mg / L of polyaluminum chloride to the domestic sewage that has already been treated with ferrate. After a coagulation process of rapid reaction (600 r / min) for 2 min and slow reaction (40 r / min) for 30 min, let it stand and settle for 30 min.

[0035] 3. The settled supernatant is pumped into a high-speed contact stabilization reactor using a peristaltic pump. The reactor's height-to-diameter ratio (H / D) is 10, and its effective working volume is 4.0 L. The reactor is pre-inoculated with high-speed activated sludge obtained from the wastewater treatment plant's sedimentation tank at a concentration of 3000 mg / L. The high-speed contact stabilization reactor operates in the following sequence: influent-contact-micro-aeration stabilization-sedimentation-discharge, with each cycle lasting 2 hours. The influent stage lasts 6 minutes, the contact stage 15 minutes, the micro-aeration stabilization stage 44 minutes, the sedimentation stage 50 minutes, and the discharge stage 5 minutes. The volume exchange ratio is 50%, and the sludge retention time (SRT) is controlled at 2 days. During the operation of the high-speed contact stabilization reactor, the apparent gas velocity during micro-aeration is 0.16 cm / s, achieving COD and PO4 in the domestic wastewater through biological adsorption or capture. 3- -P, thus completing the treatment of domestic sewage.

[0036] The experimental apparatus for treating domestic sewage in this embodiment is as follows: Figure 1 As shown, the experimental device for treating domestic sewage includes a water tank 1, an inlet peristaltic pump 3, an aeration pump 5, a sequencing batch reactor 7, and an outlet tank 9. A stirrer 2 is installed in the water tank 1. The outlet of the water tank 1 is connected to the inlet of the sequencing batch reactor 7 via a water pipe. The sequencing batch reactor 7 is cylindrical. An inlet peristaltic pump 3 is installed on the water pipe. An aeration device is installed at the bottom of the sequencing batch reactor 7. The aeration device is connected to the aeration pump 5 via an air pipe. A gas flow meter 6 is installed on the air pipe. The sequencing batch reactor 7 also has a sludge discharge port 4. The outlet 8 of the sequencing batch reactor 7 is connected to the outlet tank 9 via a pipeline. An automatic control device 10 controls the valves on the stirrer 2, the inlet peristaltic pump 3, the aeration pump 5, and the outlet 8.

[0037] In this embodiment, the COD and PO4 in the raw domestic sewage are... 3- The concentrations of -P were 190.0–340.0 mg / L and 3.0–5.0 mg / L, respectively. After 15 days of operation, this embodiment utilized a high-speed contact stabilization process enhanced by coupling ferrate with polyaluminum chloride to treat COD and PO4 in domestic sewage. 3- The removal rates of -P were 85% and 100%, respectively, and the COD concentration in the effluent was less than 50 mg / L, meeting the Class A standard for wastewater discharge in my country.

[0038] Example 2: This example describes a method for treating domestic sewage using a high-speed contact stabilization process enhanced by coupling ferrate with polyaluminum chloride, implemented according to the following steps:

[0039] 1. Add 15 mg / L of ferrate to domestic sewage and stir rapidly at 800 r / min for 15 min to dissolve the ferrate and form iron (hydrogen) oxide particles.

[0040] 2. Add 20 mg / L of polyaluminum chloride to the domestic sewage that has already been treated with ferrate. After a coagulation process of rapid reaction (600 r / min) for 2 min and slow reaction (40 r / min) for 30 min, let it stand and settle for 30 min.

[0041] 3. The settled supernatant is pumped into a high-speed contact stabilization reactor using a peristaltic pump. The reactor's height-to-diameter ratio (H / D) is 10, and its effective working volume is 4.0 L. The reactor is pre-inoculated with high-speed activated sludge obtained from the wastewater treatment plant's sedimentation tank at a concentration of 3000 mg / L. The high-speed contact stabilization reactor operates in the following sequence: influent-contact-micro-aeration stabilization-sedimentation-discharge, with each cycle lasting 2 hours. The influent stage lasts 6 minutes, the contact stage 15 minutes, the micro-aeration stabilization stage 44 minutes, the sedimentation stage 50 minutes, and the discharge stage 5 minutes. The volume exchange ratio is 50%, and the sludge retention time (SRT) is controlled at 2 days. During the operation of the high-speed contact stabilization reactor, the apparent gas velocity during micro-aeration is 0.16 cm / s, achieving COD and PO4 in the domestic wastewater through biological adsorption or capture. 3- -P, thus completing the treatment of domestic sewage.

[0042] In this embodiment, the COD and PO4 in the raw domestic sewage are... 3- The concentrations of -P were 190.0–340.0 mg / L and 3.0–5.0 mg / L, respectively. After 15 days of operation, this embodiment utilized a high-speed contact stabilization process enhanced by coupling ferrate with polyaluminum chloride to treat COD and PO4 in domestic sewage. 3- The removal rates of -P were 90% and 100%, respectively, and the COD concentration in the effluent was less than 50 mg / L, meeting the Class A standard for wastewater discharge in my country.

[0043] Example 3: This example describes a method for treating domestic sewage using a high-speed contact stabilization process enhanced by coupling ferrate with polyaluminum chloride, implemented according to the following steps:

[0044] 1. Add 20 mg / L of ferrate to domestic sewage and stir rapidly at 800 r / min for 15 min to dissolve the ferrate and form iron (hydrogen) oxide particles.

[0045] 2. Add 20 mg / L of polyaluminum chloride to the domestic sewage that has already been treated with ferrate. After a coagulation process of rapid reaction (600 r / min) for 2 min and slow reaction (40 r / min) for 30 min, let it stand and settle for 30 min.

[0046] 3. The settled supernatant is pumped into a high-speed contact stabilization reactor using a peristaltic pump. The reactor's height-to-diameter ratio (H / D) is 10, and its effective working volume is 4.0 L. The reactor is pre-inoculated with high-speed activated sludge obtained from the wastewater treatment plant's sedimentation tank at a concentration of 3000 mg / L. The high-speed contact stabilization reactor operates in the following sequence: influent-contact-micro-aeration stabilization-sedimentation-discharge, with each cycle lasting 2 hours. The influent stage lasts 6 minutes, the contact stage 15 minutes, the micro-aeration stabilization stage 44 minutes, the sedimentation stage 50 minutes, and the discharge stage 5 minutes. The volume exchange ratio is 50%, and the sludge retention time (SRT) is controlled at 2 days. During the operation of the high-speed contact stabilization reactor, the apparent gas velocity during micro-aeration is 0.16 cm / s, achieving COD and PO4 in the domestic wastewater through biological adsorption or capture. 3- -P, thus completing the treatment of domestic sewage.

[0047] In this embodiment, the COD and PO4 in the raw domestic sewage are... 3- The concentrations of -P were 190.0–340.0 mg / L and 3.0–5.0 mg / L, respectively. After 15 days of operation, this embodiment utilized a high-speed contact stabilization process enhanced by coupling ferrate with polyaluminum chloride to treat COD and PO4 in domestic sewage. 3- The removal rates of -P were 81% and 100%, respectively, and the COD concentration in the effluent was slightly higher than 50 mg / L.

[0048] Comparative Example 1: The difference between this example and Example 1 is that ferrate and polyaluminum chloride were not added.

[0049] In this embodiment, the COD and PO4 in the raw domestic sewage are... 3- The concentrations of -P were 190.0–340.0 mg / L and 3.0–5.0 mg / L, respectively. After 15 days of operation in this comparative example, the high-speed contact stabilization process effectively reduced COD and PO4 in domestic sewage. 3- The removal rates of -P were 59% and 15%, respectively. These results indicate that coupling polyaluminum chloride with ferrate can significantly enhance the removal of COD and PO4 from domestic wastewater using a high-speed contact stabilization process. 3- -P.

Claims

1. A method for treating domestic sewage using a high-speed contact stabilization process enhanced by coupling ferrate with polyaluminum chloride, characterized in that... This method for treating domestic sewage is implemented according to the following steps:

1. Add ferrate to domestic sewage and stir to dissolve the ferrate and form iron hydroxide particles; 2. Continue to add polyaluminum chloride to the domestic sewage that has already been treated with ferrate, and allow it to settle after coagulation treatment.

3. The settled supernatant is pumped into a high-speed contact stabilization reactor using a peristaltic pump. The high-speed contact stabilization reactor is pre-inoculated with activated sludge at a concentration of 2000-4000 mg / L. The activated sludge is used to adsorb or capture COD and PO4 from the domestic sewage. 3- -P, thereby completing the treatment of domestic sewage; In step three, the high-speed contact stabilization reactor is operated in the following sequence: influent - contact - micro-aeration stabilization - sedimentation - drainage. The influent stage lasts for 3-8 minutes, the contact stage lasts for 10-20 minutes, the micro-aeration stabilization stage lasts for 27-66 minutes, the sedimentation stage lasts for 40-60 minutes, the drainage stage lasts for 1-5 minutes, the volume exchange ratio is 30-70%, and the sludge retention time is controlled at 1-5 days.

2. The method for treating domestic sewage using a high-speed contact stabilization process enhanced by coupling ferrate with polyaluminum chloride as described in claim 1, characterized in that... The concentration of ferrate added in step one is 5~30 mg / L.

3. The method for treating domestic sewage using a high-speed contact stabilization process enhanced by coupling ferrate with polyaluminum chloride as described in claim 1, characterized in that... In step one, stir at a stirring speed of 500~1000 r / min for 5~20 min.

4. The method for treating domestic sewage using a high-speed contact stabilization process enhanced by coupling ferrate with polyaluminum chloride as described in claim 1, characterized in that... The mass ratio of polyaluminum chloride to ferrate added is 1:1 to 3:

1.

5. The method for treating domestic sewage using a high-speed contact stabilization process enhanced by coupling ferrate with polyaluminum chloride as described in claim 1, characterized in that... The coagulation process described in step two involves first reacting rapidly at a stirring speed of 400-800 r / min for 1-3 minutes, and then reacting slowly at a stirring speed of 10-60 r / min for 15-45 minutes.

6. The method for treating domestic sewage using a high-speed contact stabilization process enhanced by coupling ferrate with polyaluminum chloride according to claim 1, characterized in that... In step two, the settling time is 15-45 minutes.

7. The method for treating domestic sewage using a high-speed contact stabilization process enhanced by coupling ferrate with polyaluminum chloride as described in claim 1, characterized in that... The high-speed contact stabilized reactor described in step three is a cylindrical sequencing batch reactor with a height-to-diameter ratio of 8 to 12.

8. The method for treating domestic sewage using a high-speed contact stabilization process enhanced by coupling ferrate with polyaluminum chloride according to claim 1, characterized in that... In step three, during the operation of the high-speed contact stabilization reactor, the apparent gas velocity of the micro-aeration during the micro-aeration stabilization stage is 0.1~0.2 cm / s.

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