Method for determining cleaning sequence of large membrane bioreactor group system and storage medium

Abstract

The application discloses a cleaning sequence determination method and storage medium of a large-scale membrane bioreactor group system, which is based on the large-scale membrane bioreactor group system and used for realizing dynamic aeration of partition in a large-scale membrane pool, and comprises an inlet channel, a water distribution channel, a membrane pool, a reflux area, a cleaning area and a control center; the control center comprises a detection module and a control module; the detection module is used for detecting transmembrane pressure difference and water production of each channel; the control module comprises control of MBR membrane water production, control of backwashing and control of MBR membrane pollution maintenance cleaning; the MBR membrane water production and backwashing adopt a fixed rule that water production of each channel is 9 minutes, and the water production is stopped for 1 minute, and backwashing is 1 minute once in 2 hours; and then a cleaning sequence of MBR membrane pollution maintenance cleaning corresponding to a set algorithm is controlled. The application adopts a dynamic maintenance cleaning sequence, and maximally avoids problems of excessive cleaning of membrane pollution and waste of cleaning agents caused by insufficient cleaning of membrane pollution in different channels and different MBR membranes of the large-scale membrane pool caused by maintenance cleaning with a fixed period and a fixed sequence.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of membrane bioreactor cleaning, and particularly relates to a cleaning sequence determination method for a large membrane bioreactor group system. BACKGROUND

[0002] The membrane bioreactor is a new domestic sewage treatment technology combining membrane separation technology and a bioreactor, completely separates the hydraulic retention time and the sludge retention time, increases the concentration of the active sludge in the bioreactor, and thus strengthens the biodegradation of the organic matter in the domestic sewage.

[0003] However, in the actual operation process, membrane pollution is inevitable, and the high energy consumption and high cost caused by the membrane pollution are the difficulties for the wide application of the MBR. In order to slow down the membrane pollution of the MBR, the membrane surface is cleaned by using the aeration mode, and thus the energy consumption of the membrane bioreactor accounts for a high proportion (the proportion of the energy consumption of some parts is more than 40% of the energy consumption of the sewage plant). In addition, the large membrane bioreactor group is placed in the same membrane pool, the membrane pollution degree is different in different regions of the membrane pool due to the large volume of the membrane pool, the single global aeration strategy is used, and thus the excessive aeration in some regions and the insufficient aeration in some regions are caused, and the uneven distribution of the membrane pollution is caused. When the membrane pollution is cleaned, the limit membrane pressure difference set in advance is mainly used as the cleaning basis for all the membranes in the membrane pool, the membrane cleaning requirements of the membranes with different pollution degrees are not considered, and the membrane rotation cleaning time of the large membrane pool is 2-3 months. During the period, the water production of the membrane pool will be obviously reduced, the sewage cannot be efficiently treated, and if the cleaning sequence is improper, the original membrane bioreactor will be blocked more than the threshold value, and the irreversible pollution of the membrane reactor is caused, and the service life of the membrane is affected. SUMMARY

[0004] The cleaning sequence determination method for the large membrane bioreactor group system can solve at least one of the above technical problems.

[0005] To achieve the above object, the following technical scheme is adopted in the present application.

[0006] A cleaning sequence determination method of a large membrane bioreactor group system, based on a large membrane bioreactor group partition aeration energy-saving system, which is used to realize dynamic aeration of the partition of the large membrane pool, comprising an inlet channel, a water distribution channel, a membrane pool, a reflux zone, a cleaning zone and a control center, the inlet channel is connected with the front-end AAO treatment zone, the inlet channel is directly connected with the water distribution channel, the water distribution channel is connected with the membrane pool through the bottom gate, the membrane pool adopts a corridor warehouse structure, and is divided into a plurality of corridors according to the water production demand, the corridors are separated by walls to form independent treatment units; the membrane pool is connected with the reflux zone through the reflux hole at the top end of the reflux zone, and the sewage in the reflux zone is pumped to the front-end AAO treatment zone through the water pump;

[0007] The membrane bioreactor units are uniformly distributed in the corridors, the water collecting main pipes in each membrane bioreactor unit are connected with the corridor water collecting main pipes, the corridor water collecting main pipes are connected with the water outlet main pipes, and water is produced externally;

[0008] The water collecting main pipes in the membrane bioreactor units are connected with the corridor water collecting main pipes, water pumps are installed at the ends of the corridor water collecting main pipes, flow meters and pressure sensors are installed in front of the water pumps, and the water pumps are connected with the water outlet main pipes;

[0009] The corridor water collecting main pipes are provided with backwash pipes, the backwash pipes are provided with three-way electromagnetic valves, one end of the three-way electromagnetic valves is connected with the water outlet pool through a backwash pump, and the other end is connected with the maintenance cleaning pool through a backwash dosing pump;

[0010] The pressure sensors, water pumps, backwash pumps, flow meters and valves are connected to the control center through wires;

[0011] The control center comprises a detection module and a control module.

[0012] The detection module is used for detecting the transmembrane pressure difference and the water production of each corridor.

[0013] The control module comprises control of MBR membrane water production, control of backwash and control of MBR membrane pollution maintenance cleaning.

[0014] The MBR membrane water production and backwash adopt a fixed rule, specifically, water is produced for 9 minutes, stopped for 1 minute, and backwashed for 1 minute once every 2 hours.

[0015] The corresponding control of the MBR membrane pollution maintenance cleaning step comprises:

[0016] The transmembrane pressure difference Δp of the corridor is a,b,c,t and the water production q is a,b,c,t The sampling interval is 1 minute; a represents the number of maintenance cleanings, b represents the number of backwashings completed after the a-th maintenance cleaning, and c represents the number of water production stoppages after the b-th backwashing after the a-th maintenance cleaning.

[0017] S1, calculate the average transmembrane pressure difference 9min after the initial or maintenance cleaning, which is used for subsequent evaluation of the effect of repair cleaning:

[0018]

[0019] S2, calculate the average transmembrane pressure difference between the cth and c+1th water stop interval:

[0020]

[0021] S3, calculate the average transmembrane pressure difference between the bth and b+1th backwash:

[0022]

[0023] S4, the shortest interval of maintenance cleaning is set to 2 days, so at least 24 times of backwashing is needed, resulting in {f(x), f(x+2)…f(x+48)}, x=0, 2, 4, 6, …, based on the series of data, T is the specific time of a certain maintenance cleaning; let T=2b(h), adopt exponential form to construct the transmembrane pressure difference time function between the ath and a+1th maintenance cleaning by least square method:

[0024] f(T)=TMP a,T =αe βT

[0025] α and β are fitting parameters; T can be defined as the specific time of a certain maintenance cleaning;

[0026] S5, calculate the transmembrane pressure difference time function f1(T), f2(T)…fu(T) of each corridor respectively, u represents the number of corridors; u

[0027] S6, the time required for a single corridor MBR membrane to complete maintenance cleaning is ΔT, when T≥48h, every 2h, calculate according to the following method:

[0028] 1) calculate the membrane fouling prediction matrix

[0029]

[0030] Where, d ij =f i (T+(j-1)ΔT);

[0031] d ij is the membrane fouling value, i represents the ith corridor; j represents the jth time of the corridor;

[0032] 2) set the maintenance cleaning starting threshold value as f max ​, calculate the state matrix of each corridor:

[0033]

[0034] wherein, e ij is the membrane pollution factor;

[0035] 3) calculate the long period pollution factor E of each corridor j : j=1, 2, … u; E j represents the jth corridor membrane pollution time comprehensive factor;

[0036] 4) calculate the decision-making factor l j : j = j -;

[0037] l j is the positioning start-up judgment factor;

[0038] 5) analysis is carried out according to the following conditions:

[0039] If l j is less than 0, backwashing at the current T time can be carried out, and no maintenance cleaning is carried out;

[0040] If l j exists q numbers, that is q1 to q qq are from small to large, greater than or equal to 0, the current T time should immediately start maintenance cleaning, and the cleaning priority order is:

[0041] The corridor where the cleaning is located should be given priority to maintenance cleaning;

[0042] S7, when the cleaning of the corridor is clear, the cleaning order of the corridor is determined according to S1 to S6 in turn.

[0043] Further, when cleaning, the method adopts the way of pickling first and then alkaline cleaning, the pickling adopts 500-1000mg / L citric acid, and the time length is 30, and one corridor maintenance cleaning is completed at a time.

[0044] On the other hand, the application further discloses a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to make the processor execute the steps of the above method.

[0045] From the above technical solution, the cleaning order determination method of the large-scale membrane bioreactor group system has the following beneficial effects:

[0046] Considering the long cleaning period in the large membrane bioreactor group system, the dynamic maintenance cleaning sequence is adopted, the water production strategy of "9 min water production-1 min stop" is adopted, the problem of low water production of the traditional water production strategy of "8 min water production-2 min stop" is solved, and through the cleaning algorithm design, the problem of simultaneous blockage cleaning shutdown of multiple corridors existing in the water production strategy of "9 min water production-1 min stop" is effectively overcome, the remaining corridor reaches the cleaning lower limit requirement in the cleaning process, and the problem of serious membrane pollution of different corridors of the large membrane pool and different MBR membranes is avoided as much as possible. The fixed period and the fixed sequence of maintenance cleaning are carried out, and the problem of waste of cleaning agent caused by insufficient membrane pollution is avoided. At the same time, the membrane overpressure operation time is greatly reduced, and the service life of the whole membrane is improved. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1 is a system arrangement schematic diagram of the embodiment of the present application;

[0048] Figure 2 is a system arrangement schematic diagram of each corridor of the embodiment of the present application. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all the embodiments.

[0050] As Figure 1 shown, the cleaning sequence determination method of the large membrane bioreactor group system described in the embodiment of the present application is based on the large membrane bioreactor group partition aeration energy-saving system, which is mainly used to realize the partition dynamic aeration effect in the large membrane pool; including the water inlet channel, the water distribution channel, the membrane pool, the reflux area, the cleaning area and the control center.

[0051] The water inlet channel is connected with the front-end AAO treatment area, considering the area saving, is arranged on both sides, and the sewage flows into the water inlet channel through the overflow hole arranged at the bottom. The water inlet channel is directly connected with the water distribution channel, the water distribution channel is connected with the membrane pool through the bottom gate, the membrane pool adopts the corridor warehouse structure, is divided into a plurality of corridors according to the water production demand, the corridors are separated by wall, forming independent treatment units. The membrane pool is connected with the reflux area through the reflux hole at the top, the sewage in the reflux area is pumped to the front-end AAO treatment area, and the valve, gate and pump elements are controlled through the control center.

[0052] The cleaning area is mainly used for cleaning the membrane pool, and is provided with a flushing pool, an acid cleaning pool, an alkali cleaning pool, a flushing preventing pool and a standby membrane group device. The standby membrane group device is used to replace the membrane group device for operation when the membrane group device unit in the membrane pool is cleaned, so as to avoid the long time production reduction during the membrane cleaning.

[0053] As shown in Figure 2 , the membrane bioreactor units are uniformly distributed in the corridors, the water collecting main pipes in the membrane bioreactor units are connected with the corridor water collecting main pipes, the corridor water collecting main pipes are connected with the water outlet main pipe, and the water is produced externally.

[0054] The water collecting main pipes in the membrane bioreactor units are connected with the water outlet main pipe through flanges, the water outlet pumps are installed at the ends of the water collecting main pipes in the corridors, and the pressure gauges and water outlet valves are installed in front of the water outlet pumps. The aeration systems are installed at the bottoms of the membrane bioreactor units, the valves and vacuum aeration pumps are installed on the aeration main pipes in each corridor, and the ends are connected with the air compression systems.

[0055] The backwashing systems and the chemical washing systems are installed at the tops of the membrane bioreactor units, the same backwashing pipe is adopted for the backwashing systems and the chemical washing systems, the presses and backwashing pumps are installed on the backwashing pipes, the backwashing valves are installed on the backwashing systems, and the chemical washing valves are installed on the chemical washing systems.

[0056] The above pumps, valves and presses are connected with the control center.

[0057] The membrane bioreactor units adopt the upper single side fixed water outlet and the bottom free end mode, and are composed of a stainless steel fixing frame, a positioning plate, an aeration branch pipe, a rectangular jet aeration pipe, a membrane, a water collecting branch pipe and a water collecting main pipe. The rectangular jet aeration pipe is connected with the aeration branch pipe, and is used for aeration to increase the dissolved oxygen and blow the membrane surface pollution, so as to slow down the membrane blockage.

[0058] The aeration branch pipe is connected with the aeration main pipe in the corridor through flanges, and the aeration main pipe is connected with the total aeration pipe through the valve and the air blower.

[0059] The above pressure sensors, water outlet pumps, air blowers, backwashing pumps, gas flow meters, valves and other components are connected with the control center through wires, and the control center includes a detection module, a control module and a response module.

[0060] The control module includes an MBR membrane water production and backwashing module and an MBR membrane pollution maintenance and cleaning control module.

[0061] The detection module mainly detects the transmembrane pressure difference and the water production of each corridor. Taking one corridor as an example, the detection content is the transmembrane pressure difference Δp a,b,c,t and the water production q a,b,c,t, sampling interval is 1 min. a represents the number of maintenance cleaning, b represents the number of backwashing after the a th maintenance cleaning, c represents the number of water production stop after the b th backwashing after the a th maintenance cleaning.

[0062] The MBR membrane water production and backwashing module adopts a fixed rule, specifically, water production in each corridor for 9 min, stop for 1 min, 1 min of 2-hour backwashing.

[0063] The MBR membrane pollution maintenance cleaning control module adopts a dynamic rule, specifically:

[0064] (1) Calculate the average of transmembrane pressure difference in 9 min after initial or maintenance cleaning, which is used to evaluate the effect of subsequent repair cleaning:

[0065]

[0066] (2) Calculate the average of transmembrane pressure difference between the c th and c+1 th water stop intervals:

[0067]

[0068] (3) Calculate the average of transmembrane pressure difference between the b th and b+1 th backwashing:

[0069]

[0070] (4) The shortest interval of maintenance cleaning is set to 2 days, so at least 24 backwashes are required, generating {f(x), f(x+2)…f(x+48)} (x=0, 2, 4, 6, …), based on this series of data, T is the specific time of a certain maintenance cleaning, let T=2b(h), and the transmembrane pressure difference time function between the a th and a+1 th maintenance cleanings is constructed by least square method in exponential form:

[0071] f(T)=TMP a,T =αe βT

[0072] In the formula, α and β are fitting parameters.

[0073] (5) According to the above ideas (1)-(4), the transmembrane pressure difference time functions f1(T), f2(T)…f u (T) of each corridor are calculated respectively, and u represents the number of corridors.

[0074] (6) The time required for a single corridor MBR membrane to complete maintenance cleaning is ΔT, when T≥48h, every 2h, calculate according to the following method:

[0075] 1) Calculate the membrane pollution prediction matrix

[0076]

[0077] wherein d ij = f i (T+(j-1)ΔT);

[0078] d ij is the membrane fouling value, i represents the ith corridor; j represents the jth time of the corridor.

[0079] 2) Set the maintenance cleaning start threshold value f max , calculate the state matrix of each corridor:

[0080]

[0081] wherein, e ij is the membrane fouling factor;

[0082] 3) Calculate the long-period pollution factor E j of each corridor: (j=1, 2, ……u),

[0083] 4) Calculate the decision-making factor l j : l j = j -;

[0084] E j represents the jth corridor membrane fouling time comprehensive factor; l j is the positioning start judgment factor.

[0085] 5) The following cases are analyzed:

[0086] ① If l j is less than 0, backwashing at the current T time can be performed, and no maintenance cleaning is performed;

[0087] ② If l j exists q numbers (q1 to q qq from small to large) greater than or equal to 0, maintenance cleaning should be started immediately at the current T time, and the cleaning priority order is: the corridor where max is in the corridor for maintenance cleaning;

[0088] (7) When the corridor cleaning is completed, the corridor cleaning order is determined in sequence according to (1) to (6).

[0089] (8) When cleaning, the acid washing is performed first and then the alkali washing is performed, the acid washing adopts 500-1000 mg / L citric acid, and the time length is 30 min to complete one corridor maintenance cleaning.

[0090] Based on the above method, only one gallery needs to be cleaned each time the maintenance cleaning is performed, which minimizes the impact of the cleaning on the water production, effectively avoids the problem of a large reduction in production caused by the maintenance cleaning of multiple galleries at the same time, and effectively avoids the problem of a reduction in the service life of the membrane caused by the cleaning of the membrane not being in time.

[0091] In yet another aspect, the present application also discloses a computer readable storage medium storing a computer program, which, when executed by a processor, causes the processor to perform the steps of any of the above methods.

[0092] In yet another aspect, the present application also discloses a computer device comprising a memory and a processor, wherein the memory stores a computer program, and the computer program, when executed by the processor, causes the processor to perform the steps of any of the above methods.

[0093] In yet another aspect, the present application also discloses a computer program product comprising instructions which, when executed on a computer, cause the computer to carry out the steps of any of the above methods.

[0094] It can be understood that the system provided by the embodiments of the present application corresponds to the method provided by the embodiments of the present application, and the explanation, examples and beneficial effects of the related content can refer to the corresponding parts in the above method.

[0095] It can be understood by those skilled in the art that all or part of the processes in the above-mentioned embodiments can be completed by a computer program instructing related hardware, and the program can be stored in a non-volatile computer readable storage medium. When the program is executed, it can include the processes of the above-mentioned embodiments. Any reference to memory, storage, database or other medium used in the embodiments provided by the present application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration but not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0096] Any combination of the technical features in the above embodiments can be made, and for the sake of brevity, not all possible combinations of the technical features in the above embodiments are described; however, as long as the combination of the technical features does not exist in contradiction, it shall be considered within the scope of the present disclosure.

[0097] The above embodiments are only used to illustrate the technical solutions of the present application, rather than limiting them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacements for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for determining the cleaning sequence of a large-scale membrane bioreactor system, based on a zoned aeration energy-saving system for a large-scale membrane bioreactor system. This system is used to achieve dynamic aeration of zones within a large membrane tank, including an inlet channel, a distribution channel, a membrane tank, a return zone, a cleaning zone, and a control center. The inlet channel is connected to the front-end AAO treatment zone, and the inlet channel is directly connected to the distribution channel. The distribution channel is connected to the membrane tank through a gate at the bottom. The membrane tank adopts a corridor-compartment structure, divided into several corridors according to the water production requirements. The corridors are separated by walls to form independent treatment units. The end of the membrane tank is connected to the return zone through a return hole at the top. Wastewater in the return zone is pumped and converged to the front-end AAO treatment zone by a water pump. Membrane bioreactor units are evenly distributed within the corridor. The water collection trunk line in each membrane bioreactor unit is connected to the main water collection pipe of the corridor, and the main water collection pipe of each corridor is connected to the main outlet pipe for external water production. The water collection trunk line in the membrane bioreactor unit is connected to the main water collection pipe of the corridor. Each main water collection pipe of the corridor is equipped with a product water pump at the end. A flow meter and a pressure sensor are installed in front of the product water pump. The product water pump is connected to the main outlet water pipe. Each corridor's main water collection pipe is equipped with a backwash pipe, and a three-way solenoid valve is installed on the backwash pipe. One end of the three-way solenoid valve is connected to the outlet pool through a backwash water pump, and the other end is connected to the maintenance cleaning pool through a backwash chemical dosing pump. Pressure sensors, product water pumps, backwash water pumps, flow meters, valves and other components are connected to the control center via wires; Its features are, The control center includes a detection module and a control module; The detection module is used to detect the transmembrane pressure difference and water production in each corridor; The control module includes controlling MBR membrane permeate, controlling backwashing, and controlling MBR membrane fouling maintenance cleaning. The MBR membrane permeate and backwashing follow a fixed pattern, specifically: each corridor permeates water for 9 minutes, pauses for 1 minute, and backwashes once every 2 hours for 1 minute. The corresponding maintenance cleaning steps for controlling MBR membrane fouling include: Consider the transmembrane pressure difference of the corridor. and water production The sampling interval is 1 minute; a represents the number of maintenance cleanings, b represents the number of backwashes completed after the a-th maintenance cleaning, and c represents the number of times water production has stopped after the b-th backwash of the a-th maintenance cleaning. S1. Calculate the average transmembrane pressure difference over 9 minutes after the initial or maintenance cleaning is completed, to evaluate the effectiveness of subsequent corrective cleaning: ， Where t is the sampling time; S2. Calculate the average transmembrane pressure difference between the c-th and c+1-th water outage intervals: S3. Calculate the average transmembrane pressure difference between the b-th and b+1-th backwashes: S4. The minimum interval for maintenance cleaning is set to 2 days, meaning at least 24 backwashes are required to generate a series of data. }, x=0,2,4,6,... Based on this series of data, T is the specific time of a certain maintenance cleaning. Let T=2b (h), and construct the transmembrane pressure difference time function between the a-th and a+1-th maintenance cleanings in exponential form using the least squares method: and These are the fitting parameters; S5. Calculate the transmembrane pressure difference time function for each corridor. , ... u represents the number of corridors; S6. The time required for all maintenance cleaning of a single MBR membrane corridor is... ,when Every 2 hours, calculate according to the following method: 1) Calculate the membrane fouling prediction matrix in, = ; The value represents the membrane fouling value, where i represents the i-th corridor and j represents the j-th time point of that corridor. 2) Set the maintenance cleaning initiation threshold as follows: Calculate the state matrix for each corridor: in, ; Membrane fouling factors; 3) Calculate long-term pollution factors for each corridor : j=1,2,……u Represented as the comprehensive factor of membrane fouling time in the j-th corridor; 4) Calculate decision-making factors : ; To determine the starting factor; 5) Analyze according to the following situations: like If all values ​​are less than 0, then backwashing can be performed at the current time T, and no maintenance cleaning is required. like There are q numbers, i.e. Greater than or equal to 0, where to To prioritize from smallest to largest, maintenance cleaning should be initiated immediately at time T, with the cleaning priority order as follows: max( The corridor where the ) is located should be prioritized for maintenance cleaning; S7. Once the corridor cleaning is completed, determine the corridor cleaning sequence in order from S1 to S6.

2. The method for determining the cleaning sequence of a large-scale membrane bioreactor system according to claim 1, characterized in that: This also includes a cleaning process that involves acid washing followed by alkaline washing. The acid washing uses 500~1000mg / L citric acid and lasts for 30 minutes to complete the maintenance cleaning of one corridor at a time.

3. A computer-readable storage medium storing a computer program that, when executed by a processor, causes the processor to perform the steps of the method as described in claim 1 or 2.

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