A treatment device and method for secondary biochemical effluent

Abstract

The present invention relates to a treatment device and method for secondary biochemical effluent, and belongs to the technical field of wastewater treatment processes. The device of the present invention includes a reactor, a first pump body connected to the bottom of the reactor by a pipeline, a second pump body, a third pump body and a fourth pump body connected to the outer wall of the reactor; inside the reactor, a circulation zone, a transition zone and a separation zone are sequentially arranged from bottom to top, the circulation zone is a cylindrical space and is provided with two baffle plates parallel to the inner wall of the reactor; the present invention also provides a method for treating secondary biochemical effluent by using the above device. The present invention couples the bubble separation technology into the multi-phase Fenton advanced oxidation technology and completes the entire process flow through the same device, which can not only remove suspended solids, organic colloids and hydrophobic macromolecular organic matter for the Fenton reaction in advance, reduce the organic load on the Fenton reaction, but also avoid the influence of organic matter on the activity of the catalyst, improve the efficiency of the Fenton reaction and reduce the cost.

Description

Technical Field

[0001] The present invention relates to a treatment device and method for secondary biochemical effluent, and relates to the technical field of wastewater treatment processes. Background Art

[0002] With the development of industry, the types of wastewater are increasing, and there are also a large number of industrial wastewaters with complex components and high treatment difficulty. In the actual treatment process, traditional biochemical treatment has been difficult to meet the requirements of water pollution control and wastewater reuse.

[0003] Primary sewage treatment refers to the physical treatment of sewage, which is the first level in the sewage treatment level and is also called the pretreatment of sewage. By simple sedimentation, grid filtration or appropriate aeration, part of the suspended matter is removed to reduce the subsequent treatment load.

[0004] Secondary sewage treatment refers to the further treatment of sewage based on primary treatment by using biochemical action to remove colloids and dissolved organic matter in the water.

[0005] However, industrial wastewater often has the characteristics of complex composition, high salt content, high toxicity and many refractory components. After conventional primary and secondary treatment, such wastewater is often difficult to achieve ideal results and needs further treatment. At present, the treatment of secondary biochemical effluent mainly includes membrane separation method, coagulation sedimentation method, activated carbon adsorption and advanced oxidation method, etc. Among them, heterogeneous Fenton in advanced oxidation has received extensive attention due to its fast reaction speed, wide application range and strong removal ability.

[0006] However, it also has problems such as large consumption of chemicals and high treatment costs. It not only takes a lot of time and money to treat sewage, but also it is difficult to avoid the adsorption of suspended matter, organic colloid and hydrophobic macromolecular organic matter in the wastewater on the catalyst surface during the reaction process, which affects the catalytic efficiency, brings inconvenience to the treatment process, and also greatly reduces the treatment effect and efficiency.

[0007] However, at present, there is no method and equipment on the market that can both optimize the treatment efficiency of heterogeneous Fenton advanced oxidation technology and prevent wastewater from affecting the activity of the catalyst. Summary of the Invention

[0008] In order to solve the above problems, the present invention first provides a device for treating secondary biochemical effluent, including a reactor, a first pump body connected to the bottom of the reactor by a pipeline, a second pump body, a third pump body and a fourth pump body connected to the outer wall of the reactor. The first pump body is used to pump gas into the reactor, the second pump body is used to pump oxidation liquid into the reactor, the third pump body is used to pump surfactant into the reactor, and the fourth pump body is used to pump the wastewater after secondary biochemical treatment into the reactor;

[0009] Inside the reactor, a circulation zone, a transition zone, and a separation zone are sequentially arranged from bottom to top, and the reactor is not capped;

[0010] The circulation zone is a cylindrical space and is provided with two baffle plates parallel to the inner wall of the reactor. The two baffle plates are connected to the inner wall of the reactor and there is a space between the two baffle plates and the inner wall of the reactor. The area between the two baffle plates is directly above the connection between the first pump body and the reactor;

[0011] The separation zone is a cylindrical space with a cross-section larger than that of the circulation zone;

[0012] The transition zone is a frustum-shaped or trapezoidal space and is arranged between the circulation zone and the separation zone;

[0013] A plurality of sampling ports at different heights are further provided on the outer wall of the reactor.

[0014] Secondly, the present invention also provides a method for treating secondary biochemical effluent by using the above device. The method includes the following steps:

[0015] Step 1: Bubble separation stage: The wastewater after secondary biochemical treatment is pumped into the reactor by the fourth pump body until the liquid level reaches the separation zone. The third pump body is opened to pump an appropriate amount of surfactant into the reactor and then the third pump body is closed. After sufficient mixing, the third pump body is closed. The first pump body is opened to aerate the reactor and generate bubbles. The bubbles will adsorb suspended solids, organic colloids, and hydrophobic macromolecular organic matter in the wastewater in the circulation zone and rise through the transition zone to the highest liquid level in the separation zone to form a stable foam layer. The foam layer is continuously scraped until there is no stable foam layer on the liquid level, and then the first pump body is closed;

[0016] Step 2: Multi-phase Fenton reaction: A catalyst is added from the top of the reactor and the pH of the wastewater is adjusted. The second pump body is opened to add an oxidation liquid into the wastewater in the reactor; Since the aeration holes are located in the area between the two baffle plates, the bubbles generated by aeration are concentrated between the two baffle plates, and there are fewer bubbles between the two baffle plates and the inner wall of the reactor. Therefore, the liquid density between the two baffle plates is smaller than that between the two baffle plates and the inner wall of the reactor, thereby forming a phenomenon that the liquid flows from the area between the two baffle plates to the area between the baffle plates and the inner wall, forming an internal circulation movement of the liquid around the two baffle plates, so that the wastewater in the circulation zone reacts fully;

[0017] During this process, the kinetic energy is large at the lower part of the reactor, and the kinetic energy shows a decreasing trend upwards. Therefore, the carrying capacity of the gas-liquid for the catalyst particles above the reactor is weakened, and most of the catalyst particles follow the liquid phase and redeposit to the bottom of the circulation zone to participate in the circulation movement again.

[0018] In one embodiment of the present invention, in the second step, after adding a catalyst from the top of the reactor, a pH regulator is added to adjust the pH value in the reactor to 2-8, and then the sampling port is opened to sample and detect the pH value.

[0019] In one embodiment of the present invention, in the second step, multiple sampling ports are opened to sample and detect the COD in different regions.

[0020] Preferably, the sufficient reaction time of the wastewater in the circulation zone is 0.5-2h, and the COD is detected every 0.5h.

[0021] In one embodiment of the present invention, the surfactant is one or more of an ionic surfactant, a non-ionic surfactant, an amphoteric surfactant, and a compound surfactant, with a concentration of 10-40mg / L, an air flow rate of 100L / min, and it is not necessary to adjust the pH value in the reactor in the first step.

[0022] In one embodiment of the present invention, the catalyst is a metal oxide, and the addition amount of the catalyst is 0.5-3g / L; preferably, the catalyst is a Cu-Mn spinel catalyst, and the addition amount is 1g / L.

[0023] In one embodiment of the present invention, the oxidant is persulfate, and the addition amount of the oxidant is 50-200mg / L.

[0024] In one embodiment of the present invention, the surfactant is CTAB.

[0025] It should be noted that in the present invention, the connection between the reactor and the first pump body is defined as the "bottom" of the reactor, the area where the separation zone is located is defined as the "top" of the reactor, the direction from the "bottom" to the "top" is defined as "directly above", and the direction parallel to the "inner wall" and "outer wall" of the reactor is defined as the vertical direction.

[0026] The beneficial effects of the present invention:

[0027] 1. The present invention couples the bubble separation technology into the multiphase Fenton advanced oxidation technology and completes the entire process flow through the same device. It can not only remove suspended solids, organic colloids, and hydrophobic macromolecular organic matter for the Fenton reaction in advance, reduce the organic load on the Fenton reaction, but also avoid the influence of organic matter on the catalyst activity, improve the efficiency of the Fenton reaction, and reduce costs.

[0028] 2. The device used in the present invention has a compact structure, can successively complete the two technologies of bubble separation and Fenton reaction, is easy to operate, reduces the cumbersome process flow, and has a wide application prospect.

[0029] 3. During the multi-phase Fenton reaction process of the present invention, the dissolved oxygen concentration in the solution is increased in the form of aeration fluidization, the generation of singlet oxygen in the multi-phase Fenton reaction is enhanced, and the oxidation efficiency is further improved.

[0030] 4. The present invention is provided with sampling ports at multiple different heights, which can timely understand the reaction environment and reaction conditions in each area during the treatment process.

[0031] 5. Compared with the separate multi-phase Fenton reaction, the present invention can achieve a higher COD removal rate, while greatly reducing the burden of multi-phase Fenton and shortening the reaction time. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic structural diagram of the overall device in an embodiment of the present invention.

[0033] Figure 2 It is a data comparison diagram of the COD removal rate in an embodiment of the present invention compared with the separate multi-phase Fenton reaction.

[0034] Figure 3 It is a data comparison diagram of the process time when the COD removal rate reaches 55% in an embodiment of the present invention compared with the separate multi-phase Fenton reaction.

[0035] In the figure, 1: the first pump body, 2: the second pump body, 3: the third pump body, 4: the fourth pump body, 5: the aeration perforated plate, 6: the baffle plate, 7: the sampling port, 8: the water outlet and sewage outlet, 9: the reactor DETAILED DESCRIPTION OF THE EMBODIMENTS

[0036] Example 1

[0037] As Figure 1 shown, the present invention provides a treatment device for secondary biochemical effluent, including a reactor 9, a first pump body 1 connected to the bottom of the reactor 9 by a pipeline, a second pump body 2 and a third pump body 3 connected to the outer wall of the reactor 9 from bottom to top in sequence, and a fourth pump body 4. The connection between the first pump body 1 and the reactor 9 is an aeration perforated plate 5.

[0038] Inside the reactor 9, a circulation zone, a transition zone and a separation zone are arranged in sequence from bottom to top, and the reactor 9 is not capped.

[0039] The circulation zone is a cylindrical space and is provided with two baffle plates parallel to the inner wall of the reactor 9. The area between the two baffle plates 6 is directly above the aeration perforated plate 5.

[0040] The separation zone is a cylindrical space with a cross-section larger than that of the circulation zone, and the transition zone is a frustum-shaped or trapezoidal space, which is connected between the circulation zone and the separation zone.

[0041] Four sampling ports 4 at different heights are also provided on the outer wall of the reactor 9, and a water outlet and sewage drain port 8 is provided at the bottom.

[0042] Example 2

[0043] The device of Application Example 1 is used for the treatment method of the secondary biochemical effluent of spiramycin pharmaceutical wastewater, and the specific steps are as follows:

[0044] Step 1: Bubble separation stage: The spiramycin pharmaceutical wastewater after secondary biochemical treatment is pumped into the reactor 9 by the fourth pump body 4 until the liquid level reaches the height of the overflow tank in the separation zone, and the fourth pump body is closed. Subsequently, the third pump body is opened to pump CTAB into the reactor 9, and the addition amount is 20 mg / L, and the third pump body is closed. After sufficient mixing, the first pump body 1 is opened to aerate the reactor 9 to generate bubbles; the bubbles will adsorb suspended solids, organic colloids and hydrophobic macromolecular organic matters in the wastewater in the circulation zone and rise through the transition zone to the highest liquid level in the separation zone to form a stable foam layer, and the foam layer is continuously scraped until no foam layer appears on the highest liquid level; the pH value does not need to be adjusted in Step 1 until no foam layer appears, and then Step 2 can be started.

[0045] Step 2: Perform a multiphase Fenton reaction: Add a Cu-Mn spinel catalyst from the top of the reactor 9, and the addition amount is 1 g / L. Open the second pump body 2 to add an oxidant, sodium persulfate (PDS), to the wastewater in the reactor, and the addition amount is 100 mg / L. Add a pH regulator to adjust the pH value until the pH value sampled at the sampling port 4 is 4.5;

[0046] Since the area between the two guide plates 6 is directly above the aeration perforated plate 5, and there are fewer bubbles between the two guide plates 2 and the inner wall of the reactor 9, the liquid density between the two guide plates 2 is smaller than that between the two guide plates 2 and the inner wall of the reactor 9, thereby forming an internal circulation movement of the liquid around the two guide plates 2, so that the wastewater in the circulation zone reacts fully;

[0047] The entire process of Step 2 lasts for 2 h, and during this period, COD is sampled and detected through the four sampling ports 4 every 0.5 h.

[0048] Step 3: After the treatment reaches the standard, the treated water is discharged through the water outlet.

[0049] It is also possible to continue aerating with the first pump body 1. The bubbles in the circulation zone combine with the reacted liquid and catalyst particles to form a gas-liquid-solid three-phase mixture. Under the action of aeration, the three-phase mixture rises to the transition zone. Due to the decrease in the movement speed, the carrying capacity of the catalyst particles weakens, and most of the catalyst particles settle back to the circulation zone to participate in the cyclic reaction again, while a small part of the catalyst particles continue to rise with the three-phase mixture to the separation zone. When the three-phase mixture rises to the highest liquid level in the separation zone, the bubbles break due to liquid drainage and are directly discharged from the top of the reactor. The wastewater and the catalyst move in a circular motion in the reactor 9.

[0050] After the whole process is completed, the COD of the water in the collection device is detected again.

[0051] Comparative Example 1

[0052] The experimental results of a separate heterogeneous Fenton reaction under the same reaction conditions are compared with those of Example 2:

[0053] In this comparative example, no pre-treatment for bubble separation was carried out. The same dosage of Cu-Mn spinel catalyst and oxidant sodium persulfate (PDS) as in Example 2 were added to the reactor 9, and the secondary biochemical effluent of spiramycin pharmaceutical wastewater under the same conditions was treated. Finally, the treated water was detected.

[0054] After data comparison, as Figure 2 shown, compared with this comparative example, the COD removal rate in Example 2 increased by 25.2%. If a COD removal rate of 55% is used as the standard for qualified water quality, as Figure 3 shown, Example 2 reached a COD removal rate of 55% in only 30 minutes, while the separate heterogeneous Fenton reaction in the comparative example required 80 minutes.

[0055] It can be seen that the coupling process of the present invention not only reduces the treatment cost but also improves the COD removal rate.

[0056] Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this technology can make various modifications and decorations without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be defined by the claims.

Claims

1. A treatment method for secondary biochemical effluent using a treatment device for secondary biochemical effluent, characterized in that, The processing device includes a reactor, a first pump connected to the bottom of the reactor by a pipeline, a second pump connected to the outer wall of the reactor, a third pump connected to the outer wall of the reactor, and a fourth pump connected to the outer wall of the reactor. The first pump is used to pump gas into the reactor, the second pump is used to pump an oxidant into the reactor, the oxidant is persulfate, the third pump is used to pump a surfactant into the reactor, and the fourth pump is used to pump the wastewater after secondary biochemical treatment into the reactor; Inside the reactor, a circulation zone, a transition zone, and a separation zone are sequentially arranged from the bottom to the top, and the reactor is not capped; The circulation zone is a cylindrical space and is provided with two baffle plates parallel to the inner wall of the reactor. The two baffle plates are connected to the inner wall of the reactor, and the area between the two baffle plates is directly above the connection between the first pump and the reactor; The separation zone is a cylindrical space with a cross-section larger than that of the circulation zone; The transition zone is a frustum-shaped or trapezoidal space, connecting between the circulation zone and the separation zone; A plurality of sampling ports at different heights are also provided on the outer wall of the reactor; The processing method includes the following steps: Step 1: Bubble separation stage: The fourth pump pumps the wastewater after secondary biochemical treatment into the reactor until the liquid level reaches the separation zone, and then the fourth pump is closed; Subsequently, the third pump is opened to pump an appropriate amount of surfactant into the reactor, and at the same time, the first pump is opened to aerate the reactor and generate bubbles, and then the third pump is closed to stop adding the surfactant; The bubbles will adsorb suspended solids, organic colloids, and hydrophobic macromolecular organic matter in the wastewater in the circulation zone and rise through the transition zone to the highest liquid level in the separation zone to form a stable foam layer. Continuously scrape the foam layer until there is no foam layer at the highest liquid level; Step 2: Multi-phase Fenton reaction stage: The second pump is opened to add an oxidant to the wastewater in the reactor, and at the same time, a catalyst is added from the top of the reactor; Since the area between the two baffle plates is directly above the connection between the first pump and the reactor and a large number of bubbles are generated, and there are fewer bubbles between the two baffle plates and the inner wall of the reactor, the liquid density between the two baffle plates is smaller than that between the two baffle plates and the inner wall of the reactor. Therefore, a phenomenon occurs where the liquid flows from the area between the two baffle plates to the area between the baffle plates and the inner wall, forming an internal circulation movement of the liquid around the two baffle plates, so that the wastewater in the circulation zone reacts fully; In step 2, the water quality is sampled and detected through the sampling port; Step 3: After the treatment reaches the standard, the treated water is discharged through the water outlet.

2. The method according to claim 1, characterized in that, In step 2, after adding the catalyst from the top of the reactor, a pH regulator is added to adjust the pH value in the reactor to 2-8, and then the sampling port is opened to sample and detect the pH value.

3. The method according to claim 2, characterized in that In step 2, a plurality of the sampling ports are opened to sample to detect the COD in different regions.

4. The method according to claim 3, wherein In step 2, the reaction time for the wastewater in the circulation zone to react fully is 0.5-2h, and the COD is detected every 0.5h.

5. The method according to claim 1, characterized in that The surfactant is one or more of an ionic surfactant, a non-ionic surfactant, an amphoteric surfactant, and a compound surfactant, with a concentration of 10 - 40 mg / L, an air flow rate of 100 L / min, and the pH value in the reactor does not need to be adjusted in the first step.

6. The method according to claim 1, wherein The catalyst is a metal oxide, and the addition amount of the catalyst is 0.5 - 3 g / L.

7. The method according to claim 6, wherein The catalyst is a Cu-Mn spinel catalyst, and the addition amount is 1 g / L.

8. The method according to claim 1, characterized in that, The addition amount of the oxidant is 50 - 200 mg / L.

9. The method according to claim 1, characterized in that The surfactant is CTAB.

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