Activated sludge fractionation method and wastewater treatment method

Abstract

This invention provides an activated sludge sorting method and a wastewater treatment method. The activated sludge sorting method includes the following steps: supplying a portion of activated sludge from a biological treatment tank to an activated sludge sorting device; sorting the portion of activated sludge to remove sludge residue, thereby obtaining first activated sludge; and returning the first activated sludge to the biological treatment tank; measuring the organic matter content in the first activated sludge to obtain a first organic matter content; and comparing the first organic matter content with a predetermined organic matter content value to determine whether further sorting of the activated sludge in the biological treatment tank, including the first activated sludge, is necessary. By employing the activated sludge sorting method of this invention, the sorting status of the activated sludge can be monitored in real time based on the organic matter content, thereby improving the treatment effect of the activated sludge process.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment, and more specifically, to an activated sludge sorting method and a wastewater treatment method. Background Technology

[0002] The activated sludge process is a biological wastewater treatment method that uses activated sludge as the primary component. Most wastewater treatment plants using the activated sludge process face the problem of high sludge concentration and low organic matter content in their biological treatment tanks. This leads to a series of consequences: 1. Increased oxygen consumption rate, easily resulting in insufficient dissolved oxygen and anoxic conditions; 2. Nutrient deficiency causing mass microbial death; 3. Exceeding the design load of the sedimentation tank, easily causing sludge loss, and the sludge dewatering system failing to meet usage requirements; 4. Increased operational burden on the wastewater treatment plant, requiring increased blower airflow and chemical dosage to ensure stable effluent quality, resulting in wasted electricity and chemical dosage. Therefore, increasing the active components of the biological sludge, increasing the organic matter content of the sludge, and reducing the sludge concentration in the biological treatment tank are crucial. In existing technologies, when the sludge concentration is too high, simply pumping the sludge out and supplying it to the thickening tank is insufficient to effectively increase the organic matter content of the activated sludge in the biological treatment tank. Summary of the Invention

[0003] In view of the above-mentioned problems in the prior art, the present invention aims to provide an activated sludge sorting method. The activated sludge sorting method can monitor the sorting of activated sludge in real time and can automatically sort activated sludge to increase the organic matter content of activated sludge in the biological treatment tank and improve the treatment effect of the activated sludge process.

[0004] Another objective of this invention is to provide an activated sludge sorting method that can effectively backwash the screen and replace it with a matching screen as needed, thereby ensuring the sorting effect.

[0005] Another object of the present invention is to provide an activated sludge sorting method that can stably sort activated sludge and has the advantages of low cost and strong applicability.

[0006] According to one general aspect, an activated sludge sorting method is provided, the activated sludge sorting method comprising the following steps: supplying a portion of activated sludge from a biological treatment tank to an activated sludge sorting device; sorting the portion of activated sludge to remove sludge residue from the portion of activated sludge to obtain first activated sludge; and returning the first activated sludge to the biological treatment tank; measuring the organic matter content in the first activated sludge to obtain a first organic matter content; and comparing the first organic matter content with a predetermined organic matter content value to determine whether to further sort the activated sludge in the biological treatment tank, including the first activated sludge.

[0007] Preferably, the step of comparing the first organic matter content with the predetermined organic matter content value may include: calculating the fluctuation value of the first organic matter content based on Formula 1; comparing the fluctuation value of the first organic matter content with the predetermined fluctuation value to determine whether to further sort the activated sludge including the first activated sludge in the biological treatment tank.

[0008]

[0009] Wherein, α is the fluctuation value of the first organic matter content;

[0010] f1 is the content of the first organic matter; and

[0011] f s The predetermined organic matter content value.

[0012] Preferably, the activated sludge sorting method may further include: measuring the organic matter content of the activated sludge including the first activated sludge in the biological treatment tank to obtain a second organic matter content; and comparing the second organic matter content with the predetermined organic matter content value to determine whether to further sort the activated sludge including the first activated sludge in the biological treatment tank.

[0013] Preferably, the step of comparing the second organic matter content with the predetermined organic matter content value may include: determining whether to further sort the activated sludge in the biochemical tank, including the first activated sludge, based on the absolute value of the difference between the second organic matter content and the predetermined organic matter content value.

[0014] The activated sludge sorting method may further include: measuring the organic matter content in the sludge to obtain a third organic matter content; and determining the aperture of the screen in the activated sludge sorting equipment based on the third organic matter content.

[0015] The step of determining the aperture of the screen in the activated sludge sorting device based on the third organic matter content may include: determining the adjustment amount required for the third organic matter content of the sludge; and determining the aperture of the screen based on the adjustment amount.

[0016] The activated sludge sorting method may further include: adjusting the amount of activated sludge supplied to the activated sludge sorting equipment according to the sludge age of the activated sludge in the biochemical tank.

[0017] The amount of activated sludge supplied to the activated sludge sorting equipment can be determined based on Formula 2:

[0018]

[0019] Where Q is the amount of the portion of activated sludge, m 3 / h;

[0020] K is a portion of the activated sludge coefficient;

[0021] V is the effective volume of the biological treatment tank, m 3 ;

[0022] SRT is the sludge age (d) of the activated sludge in the biological treatment tank; and

[0023] T is the working time of the activated sludge sorting equipment, in hours.

[0024] The activated sludge sorting equipment may include a movable nozzle and a screen for screening the portion of activated sludge. The movable nozzle may be configured to rinse the screen. The step of supplying a portion of activated sludge from the biological treatment tank to the activated sludge sorting equipment for sorting the portion of activated sludge may include: during the screening of the portion of activated sludge by the screen, rinsing the screen while the movable nozzle reciprocates along the extension direction of the screen.

[0025] The predetermined organic matter content value can be set based on the type of wastewater to be treated.

[0026] According to another general aspect, a wastewater treatment method is provided, which may include the activated sludge sorting method described above.

[0027] The activated sludge sorting method according to an exemplary embodiment of the present invention can monitor the sorting of activated sludge in real time based on the organic matter content in the activated sludge, thereby increasing the organic matter content of the activated sludge in the biological treatment tank and improving the treatment effect of the activated sludge process.

[0028] The activated sludge sorting method according to an exemplary embodiment of the present invention can reliably backwash the screen by using a movable backwash nozzle, which can improve the backwashing effect and effectively prevent the screen from being blocked. Furthermore, it can replace the screen with a matching screen according to the change in the organic matter content in the discharged sludge, thereby ensuring the screening effect. Therefore, it can ensure the stable operation of the system and ensure that the organic matter content of the activated sludge in the biological treatment tank is increased.

[0029] Furthermore, the activated sludge sorting method according to an exemplary embodiment of the present invention can stably sort sludge and has the advantages of low cost and strong applicability. Attached Figure Description

[0030] The above and other aspects, features and other advantages of the present invention will become clearer and more readily understood from the following detailed description of exemplary embodiments in conjunction with the accompanying drawings.

[0031] Figure 1 This is a schematic diagram illustrating an activated sludge treatment system including an activated sludge sorting device according to an embodiment of the present invention.

[0032] Figure 2 This is a schematic diagram illustrating an activated sludge sorting device according to an embodiment of the present invention.

[0033] Figure 3 It is shown Figure 2 A partial schematic diagram of the backwashing components of an activated sludge sorting device.

[0034] Figure 4 This is a flowchart illustrating an activated sludge sorting method according to an embodiment of the present invention.

[0035] Figure 5 This is a graph showing the organic matter content versus time during the process of using the activated sludge sorting method according to an embodiment of the present invention.

[0036] Explanation of reference numerals in the attached figures:

[0037] 1-Activated sludge treatment system; 10-Biological tank; 20-Thickening tank; 30-Activated sludge sorting equipment; 310-Inlet assembly; 311-Inlet pump; 312-Inlet pipe; 320-Screen assembly; 321-Divider plate; 322-Screen; 323-Collection plate; 330-Backwash assembly; 331-Backwash pump; 332-Backwash pipe; 3321-Backwash hose; 3322-Backwash rigid pipe; 333-Backwash nozzle (also known as "mobile nozzle"); 334-Guide rail; 340-Drainage assembly; 341-Collection hopper; 342-Outlet pipe; 350-Sludge discharge assembly; 351-Sludge hopper; 352-Sludge discharge pipe; 353-Sludge discharge pump; 360-Supporting components; and 370-Automatic control module. Detailed Implementation

[0038] The following detailed embodiments are provided to aid the reader in gaining a comprehensive understanding of the methods, apparatus, and / or systems described herein. However, after understanding the disclosure of this application, various modifications, variations, and equivalents of the methods, apparatus, and / or systems described herein will be readily apparent. For example, the order of operations described herein is merely illustrative and is not limited to the order set forth herein; rather, changes may be made, as will be readily apparent after understanding the disclosure of this application, except for operations that must be performed in a specific order. Furthermore, for clarity and brevity, descriptions of features known after understanding the disclosure of this application may be omitted; note that omitting features and their descriptions is not intended to acknowledge that they are publicly known.

[0039] The features described herein may be implemented in different forms and shall not be construed as limited to the examples described herein. Rather, the examples described herein have been provided only to illustrate some of the many feasible ways of implementing the methods, apparatus, and / or systems described herein that will be readily understood upon understanding the disclosure of this application.

[0040] Furthermore, unless otherwise defined, all terms used herein, including technical and scientific terms, shall have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains, upon understanding the disclosure of this application. Terms (such as those defined in commonly used dictionaries in the context of this art) shall be interpreted as having a meaning consistent with their meaning in the context of the relevant technology and the disclosure of this application, and shall not be interpreted as having an idealized or overly formal meaning unless expressly defined herein.

[0041] In the process of wastewater treatment using the activated sludge method, as the wastewater treatment time increases, problems such as increased sludge concentration and decreased organic matter content in the biological treatment tank may occur, thus affecting the stable operation of the biological treatment tank.

[0042] To address the aforementioned issues, the main concept of this invention lies in using the ratio of volatile suspended solids concentration (MLVSS) to MLSS in the mixed liquor of the biological treatment tank as a basis. Activated sludge is then separated in real time using an activated sludge sorting device to remove sludge residue. The sorted activated sludge with high organic matter content is then returned to the biological treatment tank, thereby increasing the organic matter content and ensuring the stable operation of the biological treatment tank.

[0043] The method for sorting activated sludge according to the present invention operates based on the difference between the organic matter content in the activated sludge and a predetermined organic matter content value, and is implemented using activated sludge sorting equipment. The organic matter content of the activated sludge can be obtained based on the following formula 1:

[0044]

[0045] Wherein, MLVSS represents the concentration of volatile suspended solids in the mixture (mg / L); and

[0046] MLSS represents the concentration of suspended solids in a liquid mixture (mg / L).

[0047] Specifically, MLSS, or Mixed Liquor Sludge Concentration, represents the total weight (mg / L) of activated sludge solids. MLSS is the total amount of active microorganisms (Ma), microbial auto-oxidation residues (Me), non-biodegradable organic matter adsorbed on the sludge (Mi), and inorganic matter (Mii), i.e., MLSS = Ma + Me + Mi + Mii. MLVSS, or Organic Solids Concentration, represents the concentration of organic solids or biomass in the activated sludge of the mixed liquor. MLVSS refers to the mass of organic matter in the suspended solids of the mixed liquor (usually measured by loss on ignition at 600°C), i.e., MLVSS = Ma + Me + Mi. Therefore, compared to MLSS, MLVSS more accurately represents the quantity of activated sludge microorganisms.

[0048] The activated sludge sorting apparatus and activated sludge sorting method according to the present invention will be described in detail below.

[0049] Figure 1 This is a schematic diagram illustrating an activated sludge treatment system including an activated sludge sorting device according to an embodiment of the present invention.

[0050] like Figure 1 As shown, the activated sludge treatment system 1 may include a biological treatment tank 10, a thickening tank 20, and an activated sludge sorting device 30, wherein the activated sludge sorting device 30 may include an influent pump 311, a sludge discharge pump 353, and an automatic control module 370. It should be understood that the activated sludge treatment system 1 may also include other equipment (known, but not shown for simplicity).

[0051] The influent pump 311 can be configured to pump a portion of the activated sludge from the biological treatment tank 10 to the main structure of the activated sludge sorting device 30. The activated sludge sorting device 30 can be configured to sort or screen the activated sludge to separate it, thereby returning the treated activated sludge with smaller particle size and higher organic matter content to the biological treatment tank 10, and removing or discharging larger particle size sludge (or impurities). For example, larger particle size sludge can be discharged to the thickening tank 20 via the sludge discharge pump 353.

[0052] The automatic control module 370 can be configured to control the operation of the activated sludge sorting device 30. Specifically, the automatic control module 370 can control the start and stop of the activated sludge sorting device 30 via control signals. As an example, the automatic control module 370 can control the operation of the influent pump 311 and the sludge discharge pump 353 via control signals. Additionally, see below. Figure 4 The described activated sludge sorting method can be automatically executed by an automatic control module to achieve automatic sorting of activated sludge.

[0053] Figure 2 This is a schematic diagram illustrating an activated sludge sorting device according to an embodiment of the present invention, and Figure 3 It is shown Figure 2 A partial schematic diagram of the backwashing components of an activated sludge sorting device.

[0054] like Figure 2 As shown, the activated sludge sorting device 30 may include an inlet assembly 310, a screen assembly 320, a backwashing assembly 330, a drainage assembly 340, a sludge discharge assembly 350, and a support member 360. Furthermore, the support member 360 may be configured to support the main structure of the activated sludge sorting device 30 at an inclination relative to the horizontal direction to facilitate the flow of activated sludge and aid in its sorting.

[0055] The water inlet assembly 310 may include a water inlet pump 311 and a water inlet pipe 312 connected to each other. Specifically, the lower end of the water inlet pipe 312 may be connected to the water inlet pump 311, while the upper end of the water inlet pipe 312 may be connected to the water distribution plate 321 of the screen assembly 320 (described later).

[0056] The screen assembly 320 may include a water distribution plate 321, a screen 322, and a water collection plate 323. Specifically, the water distribution plate 321 may be inclined relative to the screen 322 to buffer the activated sludge flowing out from the inlet pipe 312. The screen 322 may screen the activated sludge flowing through the water distribution plate 321, and the water collection plate 323 may be arranged substantially parallel to the screen 322 below the screen 322 to collect the activated sludge to be returned to the biological treatment tank. In addition, the screen 322 may be constructed to be portable and / or detachable, and the screen with an aperture between 100 μm and 600 μm may be freely selected as needed, as will be described in detail later.

[0057] like Figure 2 and Figure 3 As shown, the backwash assembly 330 may include a backwash pump 331, a backwash pipe 332, a backwash nozzle 333, and a guide rail 334. The backwash pipe 332 may include a backwash hose 3321 and a backwash rigid pipe 3322, and the backwash pump 331 may be connected to the backwash rigid pipe 3322 via the backwash hose 3321.

[0058] Additionally, the backwash nozzle 333 can be mounted on the backwash rigid pipe 3322, and the backwash nozzle 333 can be connected to guide rails 334 arranged in pairs on both sides of the support 360 in the extending direction of the screen 322, so that the backwash nozzle 333 can reciprocate on the screen 322 via the guide rails 334 during use. Therefore, by constructing the backwash nozzle 333 as movable, it can be moved along the guide rails 334 while rinsing the screen 322 during the operation of the activated sludge sorting equipment, thereby preventing the screen 322 from being blocked by sludge, etc. The method of constructing the backwash nozzle 333 as movable is not limited to the method of using paired guide rails as shown. For example, a single guide rail can be provided centrally at the top of the backwash nozzle 333, or other methods without guide rails can be used. As an example, the backwash nozzle can be set in 2-4 rows, but is not limited to this, and can be set in a single row or more than 4 rows of backwash nozzles as needed.

[0059] Therefore, the backwashing component 330 can prevent the screen 322 from being blocked during the operation of the activated sludge sorting equipment 30, thereby ensuring the reliable operation of the activated sludge sorting equipment 30.

[0060] The drainage assembly 340 may include a water collection hopper 341 and a water outlet pipe 342. The water collection hopper 341 may be connected to a water collection plate 323 and is located downstream of the water collection plate 323. In addition, the water collection hopper 341 may be connected to the water outlet pipe 342, so that the liquid collected through the water collection hopper 341 flows back to the biological treatment tank 10 by gravity.

[0061] The slag discharge assembly 350 may include a slag collection hopper 351, a slag discharge pipe 352, and a slag discharge pump 353. The slag collection hopper 351 may be connected to a screen 322 and disposed downstream of the screen 322. In addition, the slag collection hopper 351 may be connected to the slag discharge pipe 352 and the slag discharge pump 353, thereby discharging the sludge collected via the slag collection hopper 351.

[0062] Figure 4 This is a flowchart illustrating an activated sludge sorting method according to an embodiment of the present invention.

[0063] like Figure 4 As shown, in step 101, the activated sludge sorting device 30 is operated to supply a portion of the activated sludge in the biological treatment tank 10 to the activated sludge sorting device 30, and this portion of activated sludge is sorted to remove the sludge residue in this portion of activated sludge, thereby obtaining the first activated sludge, and the first activated sludge is returned to the biological treatment tank 10.

[0064] During the screening of this portion of activated sludge using the screen 322 of the activated sludge sorting equipment 30, the backwash nozzles reciprocate along the extension direction of the screen 322 while rinsing the screen 322 to prevent it from becoming clogged, thereby improving the operational stability of the activated sludge sorting equipment 30.

[0065] Next, in step 102, the organic matter content in the first activated sludge is measured to obtain the first organic matter content.

[0066] Specifically, the organic matter content in the first activated sludge can be measured by sampling at the effluent pipe 342 of the activated sludge sorting device 30. As an example, MLVSS1 and MLSS1 can be measured at the effluent pipe 342 of the activated sludge sorting device 30, and the first organic matter content can be obtained according to Formula 2 below.

[0067]

[0068] Wherein, f1 represents the first organic matter content (%) of the first activated sludge at the outlet pipe 342 of the activated sludge sorting equipment 30;

[0069] MLVSS1 represents the volatile suspended solids concentration of the mixed liquor at the effluent pipe 342 of the activated sludge sorting equipment 30, and the unit can be mg / L; and

[0070] MLSS1 represents the concentration of suspended solids in the mixed liquor at the outlet pipe 342 of the activated sludge sorting equipment 30, and the unit can be mg / L.

[0071] Next, in step 103, the first organic matter content is compared with a predetermined organic matter content value to determine whether the activated sludge in the biological treatment tank 10, including the first activated sludge, should be further sorted.

[0072] For example, in step 103, the fluctuation value of the first organic matter content can be calculated based on the following formula 3, and the fluctuation value of the first organic matter content can be compared with the predetermined fluctuation value to determine whether to further sort the activated sludge including the first activated sludge in the biological treatment tank 10, that is, to determine whether to control the activated sludge sorting equipment 30 to continue operating.

[0073]

[0074] Where α represents the fluctuation value (%) of the first organic matter content;

[0075] f1 represents the first organic matter content (%); and

[0076] f s This indicates the predetermined organic matter content value (%).

[0077] The organic matter content of activated sludge in wastewater treatment plants is usually related to the type of wastewater being treated. For example, in wastewater treatment plants primarily treating domestic sewage, the organic matter content of activated sludge is in the range of 50%-65%, while in wastewater treatment plants primarily treating industrial wastewater, the organic matter content is in the range of 30%-50%. Therefore, the concentration of activated sludge (f) can be set according to the type of wastewater the plant is treating. s As an example, f s It can be 39%, 45%, 49%, etc.

[0078] In step 103, it is determined whether α exceeds a predetermined fluctuation value. When it is determined in step 103 that α exceeds the predetermined fluctuation value (i.e., the branch "Yes"), the method returns to step 101 and continues to operate the activated sludge sorting equipment 30, thereby increasing the organic matter content in the activated sludge treated by the activated sludge sorting equipment 30. When α is less than or equal to the predetermined fluctuation value (i.e., the branch "No"), the method may proceed to step 104 as needed to further determine whether to stop operating the activated sludge sorting equipment 30, that is, to further determine whether to continue further sorting of the activated sludge in the biological treatment tank 10. Regarding the predetermined fluctuation value, as an example, the predetermined fluctuation value can be in the range of 5%-10%, and preferably less than or equal to 5%.

[0079] In step 104, the organic matter content of the activated sludge, including the first activated sludge, in the biological treatment tank 10 is measured to obtain the second organic matter content.

[0080] Specifically, after the activated sludge, sorted by the activated sludge sorting device 30, is returned to the biological treatment tank 10, the organic matter content of the activated sludge in the current biological treatment tank 10, including a portion of the treated activated sludge, is measured by sampling. As an example, the MLVSS2 and MLSS2 of the current activated sludge can be measured in the biological treatment tank 10, and the second organic matter content can be obtained according to Formula 4 below.

[0081]

[0082] Wherein, f2 represents the second organic matter content (%) of the activated sludge in the biological treatment tank 10, including the first activated sludge;

[0083] MLVSS2 represents the volatile suspended solids concentration of the mixed liquor containing the first activated sludge in biological treatment tank 10, and the unit can be mg / L; and

[0084] MLSS2 represents the concentration of suspended solids in the mixed liquor of activated sludge, including the first activated sludge, in biological treatment tank 10, and the unit can be mg / L.

[0085] Next, in step 105, the second organic matter content is compared with a predetermined organic matter content value to determine whether the activated sludge in the biological treatment tank 10, including the first activated sludge, should be further sorted.

[0086] For example, in step 105, it can be determined whether to further sort the activated sludge in the biological treatment tank, including the first activated sludge, based on the absolute value of the difference between the second organic matter content and the predetermined organic matter content value. In other words, the second organic matter content in the biological treatment tank 10 can be compared with the preset organic matter content value based on the following formula 5 to determine whether the activated sludge sorting equipment 30 is operating maturely and stably.

[0087] β=|f2-f s | Formula 5 Wherein, β represents the absolute value of the difference between the second organic matter content and the predetermined organic matter content value;

[0088] f2 represents the second organic matter content (%) in biological tank 10; and

[0089] f s This indicates the preset organic matter content value (%).

[0090] The second organic matter content f2 of biological tank 10 is different from the preset organic matter content value f. s There is an inherent correlation between them, which is one of the key parameters for determining whether the activated sludge sorting equipment is operating maturely and stably. In other words, it is one of the key parameters for determining whether to further sort the activated sludge (including the sorted activated sludge) in the biological treatment tank.

[0091] Specifically, as the activated sludge sorting equipment 30 operates, the second organic matter content f2 in the biological treatment tank differs from the preset organic matter content value f. s The absolute value β of the difference between the two will gradually decrease. The smaller β is, the better the operating effect of the activated sludge sorting equipment 30. When the activated sludge sorting equipment 30 has been running for a long enough time, the absolute value β of the difference approaches 0. At this point, it can be determined that the activated sludge sorting equipment 30 is operating maturely and stably.

[0092] Therefore, in step 105, it is determined whether the absolute value of the difference between the second organic matter content and the preset organic matter content value is close to 0. If β is close to 0 (i.e., the branch "Yes"), then in step 106, it can be determined that the mobile activated sludge sorting device is operating maturely and stably, and no further sorting of the sludge in the biological treatment tank is required. Here, considering measurement tolerances or errors, the value "0" should be understood as less than a value including tolerances or errors, for example, less than or equal to 0.5. If β is not close to 0 (i.e., the branch "No"), then in step 107, it is possible to return to step 101 to continue sorting the activated sludge in the biological treatment tank, or the activated sludge sorting device 30 can be adjusted. For example, if β cannot approach 0 when the activated sludge sorting device 30 has run for a predetermined time or has completed a predetermined number of sorting cycles of the activated sludge in the biological treatment tank, then the activated sludge sorting device 30 can be adjusted. The adjustment includes, but is not limited to, adjusting the pumping rate of activated sludge and replacing the screen.

[0093] As described above, in the embodiments of the present invention, activated sludge is sorted according to the organic matter content in the activated sludge, thereby increasing the organic matter content of the activated sludge in the biological treatment tank and improving the treatment effect of the activated sludge process.

[0094] Optionally, the activated sludge sorting method according to the present invention may include determining whether it is necessary to adjust the aperture of the screen and replace the screen to enhance the operational stability of activated sludge sorting and ensure that the organic matter content of the activated sludge in the biological treatment tank is increased, thereby improving the treatment effect of the activated sludge process.

[0095] Specifically, the sludge discharged by the sludge discharge pump 353 of the activated sludge sorting equipment 30 contains a large amount of inorganic matter (such as silt) and some organic matter. The inorganic matter in the sludge can be divided into: water-soluble inorganic matter, mainly including water-soluble oxides and salts such as K, Na, Ca, and Mg; and water-insoluble inorganic matter, mainly including oxides such as Fe and Al, and SiO2 inorganic sand. Since water-soluble inorganic matter cannot be removed by physical sorting methods, it can be ignored here, and only water-insoluble inorganic matter is considered.

[0096] In addition to the density difference, organic and inorganic matter also differ in particle size. In typical wastewater treatment plants, the particle size of activated sludge containing organic matter is usually in the range of 50μm-110μm, while the particle size of inorganic matter (i.e., non-water-soluble inorganic matter) is usually in the range of 80μm-250μm.

[0097] Here, the organic matter content in the sludge discharged from the sludge discharge pump 353 of the activated sludge sorting device 30 will be measured to obtain a third organic matter content, and the aperture of the screen 322 in the activated sludge sorting device 30 will be determined based on the third organic matter content.

[0098] For example, in this embodiment, the content of the third organic matter in the sludge can be related to the aperture of the screen, wherein the content of the third organic matter can be obtained according to Formula 1 above.

[0099] Assuming the aperture of sieve 322 is 100 μm, in this case, if it is necessary to reduce the content of the third organic matter by 5%-8% (i.e., increase the content of inorganic matter in the sludge by 5%-8%), then the aperture of sieve 322 needs to be reduced by 10 μm-20 μm. Therefore, the content of the third organic matter and the aperture of sieve 322 have the relationship shown in Formula 6 below.

[0100] Δd=k×Δf Formula 6 Where Δd represents the amount by which the aperture d of the screen needs to change;

[0101] Δf3 represents the change in the content of the third organic matter; and

[0102] k represents the correlation coefficient between Δd and Δf3.

[0103] Therefore, the required adjustment amount for the third organic matter content of the sludge can be determined here, and the aperture of the screen 322 can be determined based on this adjustment amount.

[0104] Optionally, the activated sludge sorting method according to the present invention may include the step of adjusting the pumping rate of activated sludge into the activated sludge sorting equipment.

[0105] In other words, the activated sludge sorting method according to the present invention may further include: adjusting the amount of activated sludge supplied to the activated sludge sorting equipment according to the sludge age of the activated sludge in the biological treatment tank, wherein the sludge age is the ratio of the total amount of activated sludge in the biological treatment tank to the amount of sludge discharged daily, and the sludge age can be used to select the types of microorganisms in the activated sludge.

[0106] For example, the amount of activated sludge supplied to the activated sludge sorting device 30 can be determined based on the following formula 7:

[0107]

[0108] Where Q is a portion of the activated sludge, m 3 / h;

[0109] K is a part of the activated sludge coefficient;

[0110] V is the effective volume of the biological treatment tank, m 3 ;

[0111] SRT is the sludge age (d) of the activated sludge in the biological treatment tank; and

[0112] T is the working time of the activated sludge sorting equipment, in hours.

[0113] Wherein, K is a preset value. K should be greater than 1 and less than 1.5. For example, it can be 1.05, 1.08 or 1.10, but it is not limited to these. The value of K can be set according to actual needs.

[0114] Therefore, the pumping volume of activated sludge into the activated sludge sorting equipment can be adjusted according to the sludge age to ensure that activated sludge can be sorted effectively in real time, thereby increasing the organic matter content in the biological treatment tank.

[0115] Below, in conjunction with Figure 5 An application example of the sludge sorting method according to the present invention is described. Figure 5 This is a graph showing the organic matter content versus time during the process of using the activated sludge sorting method according to an embodiment of the present invention.

[0116] Specifically, a wastewater treatment plant in northern China adopts the AAO process and uses the activated sludge sorting equipment 30 according to the embodiment, wherein the effective volume V of the biological treatment tank is 10000 m³. 3 The activated sludge pumping rate of the activated sludge sorting equipment 30 is 37m³ per cycle. 3 The activated sludge sorting equipment 30 operates for 9 hours per day, with a sludge age SRT of 30 days. The organic matter content of the effluent (i.e., the organic matter content of the activated sludge at the effluent pipe 342 of the activated sludge sorting equipment 30) f1 represents the organic matter content of the activated sludge after passing through the activated sludge sorting equipment, and the organic matter content of the influent f2 represents the organic matter content in the biological treatment tank 10. The organic matter content f is set as follows: s The organic matter content was 49%, indicating that when using a sieve with a mesh size of 150 μm, the fluctuation value α of the organic matter content was less than 5%, and on the 8th day of operation, the absolute value β of the difference in sludge organic matter content tended to 0.2. Therefore, the organic matter content of the activated sludge in the biological treatment tank of this wastewater treatment plant increased by 3%-5%, and the organic matter content of the effluent sludge remained stable at 49%.

[0117] As described above, the activated sludge sorting method proposed in this invention can monitor the sorting of activated sludge in real time based on the organic matter content in the activated sludge, thereby increasing the organic matter content of the activated sludge in the biological treatment tank and improving the treatment effect of the activated sludge process.

[0118] As described above, the activated sludge sorting method proposed in this invention can reliably backwash the screen using a mobile backwash nozzle, thereby improving the backwashing effect and effectively preventing the screen from being blocked. Furthermore, screens with different apertures can be replaced according to the changes in the organic matter content in the discharged sludge, thereby ensuring the screening effect. Therefore, the system can be guaranteed to operate stably and the organic matter content of the biological treatment tank can be increased.

[0119] In addition, the activated sludge sorting method proposed in this invention has the advantages of strong applicability, low cost and simple operation, and therefore it can be applied to wastewater treatment plants that use the existing activated sludge process.

[0120] The specific embodiments of the present invention have been described in detail above. Although some embodiments have been shown and described, those skilled in the art should understand that these embodiments can be combined, modified, and improved without departing from the principles and spirit of the invention as defined by the claims (for example, different technical features of the present invention can be combined to obtain new technical solutions). These combinations, modifications, and improvements should also be within the protection scope of the present invention.

Claims

1. A method for sorting activated sludge, characterized in that, The activated sludge sorting method includes the following steps: A portion of the activated sludge in the biological treatment tank is supplied to an activated sludge sorting device to sort the activated sludge to remove the sludge residue, thereby obtaining the first activated sludge, and the first activated sludge is returned to the biological treatment tank. The organic matter content in the first activated sludge is measured to obtain the first organic matter content; and The first organic matter content is compared with a predetermined organic matter content value to determine whether the activated sludge in the biochemical tank, including the first activated sludge, needs to be further sorted. The step of comparing the first organic matter content with the predetermined organic matter content value includes: The fluctuation value of the first organic matter content is calculated based on Formula 1; The fluctuation value of the first organic matter content is compared with a predetermined fluctuation value to determine whether further sorting of the activated sludge, including the first activated sludge, in the biological treatment tank is required. Wherein, α is the fluctuation value of the first organic matter content; f1 is the content of the first organic matter; and f s The predetermined organic matter content value; The activated sludge sorting method further includes: The organic matter content of the activated sludge, including the first activated sludge, in the biological treatment tank is measured to obtain the second organic matter content; and The second organic matter content is compared with the predetermined organic matter content value to determine whether the activated sludge in the biological treatment tank, including the first activated sludge, should be further sorted. Based on the absolute value of the difference between the second organic matter content and the predetermined organic matter content value, it is determined whether to further sort the activated sludge in the biochemical tank, including the first activated sludge.

2. The activated sludge sorting method according to claim 1, characterized in that, The activated sludge sorting method further includes: The organic matter content in the sludge was measured to obtain a third organic matter content; and The aperture of the screen in the activated sludge sorting equipment is determined based on the third organic matter content.

3. The activated sludge sorting method according to claim 2, characterized in that, Based on the aforementioned third organic matter content The step of determining the aperture of the screen in the activated sludge sorting equipment includes: determining the adjustment amount required for the third organic matter content of the sludge; and determining the aperture of the screen based on the adjustment amount.

4. The activated sludge sorting method according to claim 1, characterized in that, The activated sludge sorting method further includes: The amount of activated sludge supplied to the activated sludge sorting equipment is adjusted according to the sludge age of the activated sludge in the biochemical tank.

5. The activated sludge sorting method according to claim 4, characterized in that, Supply to the activated sludge sorting equipment The amount of activated sludge in the preparation is determined based on Formula 2: Where Q is the amount of the portion of activated sludge, m 3 / h; K is a portion of the activated sludge coefficient; V is the effective volume of the biological treatment tank, m 3 ; SRT is the sludge age (d) of the activated sludge in the biological treatment tank; and T is the working time of the activated sludge sorting equipment, in hours.

6. The activated sludge sorting method according to claim 1, characterized in that, The activated sludge sorting equipment includes a movable nozzle and a screen for screening a portion of the activated sludge. The movable nozzle is configured to rinse the screen. The step of supplying a portion of the activated sludge from the biochemical tank to an activated sludge sorting device for sorting the activated sludge includes: during the screening of the activated sludge by the screen, the screen is rinsed while the movable nozzle reciprocates along the extension direction of the screen.

7. The activated sludge sorting method according to claim 1, characterized in that, The predetermined organic matter content value is set based on the type of wastewater to be treated.

8. A wastewater treatment method, characterized in that, The wastewater treatment method includes the activated sludge sorting method according to any one of claims 1 to 7.

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