Intelligent cleaning method for MBR (Membrane bioreactor)
Technical Field
The invention relates to the field of sewage treatment, in particular to an intelligent cleaning method for an MBR (Membrane bioreactor).
Background
The Membrane Bioreactor (MBR) technology is a novel technology for modern sewage treatment, compared with the traditional sewage treatment technology, the MBR technology has the advantages of small occupied area, stable effluent quality and the like, traditional MBR cleaning is generally carried out according to a fixed period, emptying, water supplementing, medicine adding, soaking and other stages are sequentially carried out when a cleaning mode is entered, as the cleaning process is carried out according to a time period, the judgment of the cleaning effect is carried out according to the time period, if the water yield is still lower, the cleaning is not thorough, the intelligent and other next periods are required to be cleaned, and the cleaning effect is still known after the cleaning is completed, the Membrane pollution is more and more serious due to the sequential circulation according to the process;
meanwhile, the liquid level monitoring of the membrane tank adopts an ultrasonic liquid level meter at present, but because the membrane tank is positioned in a sealed or semi-sealed space and the concentration of sludge in the membrane tank is higher, foam is generally formed at 8000 mg/L-12000 mg/L during aeration, the ultrasonic liquid level meter is easily distorted in detection due to the foam formed during aeration, so that the sewage is drained while the membrane tank is emptied, and the emptying pump is still in dry running, so that the equipment is damaged.
Disclosure of Invention
The invention provides an intelligent cleaning method of an MBR (Membrane bioreactor), which is characterized in that after entering a cleaning mode, an emptying pump outside a membrane tank completely empties the cleaning membrane tank according to the emptying time calculated by the slope of the liquid level and the running time; according to parameters such as outlet pressure of a backwashing pipeline, a relation value of flow and frequency before cleaning (water flow produced per unit frequency) and the like in the water supplementing process, the soaking time after water supplementing is calculated; when the rest 5 minutes of the soaking procedure are reached, increasing the aeration quantity of the cleaning membrane pool; the method has the advantages that the backwashing is carried out every half hour during the dosing soaking period, the soaking time is calculated again according to the backwashing pressure, and the membrane components in the cleaning membrane tank can be effectively cleaned, so that the pollution of the membrane bioreactor is delayed, the cleaning time is shortened, and the water production efficiency is improved.
The technical scheme of the invention is realized as follows:
an intelligent cleaning method and a cleaning method for an MBR (Membrane biological reactor), wherein the MBR comprises the following steps:
the membrane tank is internally provided with an ultrasonic liquid level meter and an aeration system;
the membrane component is arranged in the membrane pool;
the back washing pump is connected with a back washing main pipe, and the back washing main pipe is connected with a back washing pipeline for communication;
a backwash pressure gauge and an electromagnetic flowmeter are arranged on the backwash header pipe;
a first branch backwash pipeline is communicated with the backwash pipeline, and is simultaneously communicated with the backwash main pipe and the backwash main pipe, and a backwash valve is arranged on the first branch backwash pipeline;
a second branch backwash pipeline is communicated with the backwash pipeline, each second branch backwash pipeline is communicated with the backwash pipeline and the membrane pool, and a water supplementing valve is arranged on the second branch backwash pipeline;
the water producing pipeline is communicated with the membrane pool, and a water producing pressure gauge is arranged on the water producing pipeline;
the aeration system comprises an air blower, a plurality of sets of aeration branch pipes and a plurality of pneumatic butterfly valves, wherein the aeration branch pipes are communicated with the air blower, one pneumatic butterfly valve is arranged on one aeration branch pipe, and the aeration branch pipes are communicated with the membrane tank;
the number of the membrane tanks is N, N is an integer, and N is more than or equal to 2;
m membrane components are arranged in each membrane pool, and M is more than or equal to 1;
the water producing pipelines are provided with N water producing pipelines which are respectively communicated with the N membrane tanks;
the membrane pool control system comprises an ultrasonic liquid level meter, a membrane assembly, a backwash pump, a backwash pressure gauge, an electromagnetic flowmeter, a backwash valve, a water supplementing valve, a water production pressure gauge, a blower and a plurality of pneumatic butterfly valves, wherein the ultrasonic liquid level meter, the membrane assembly, the backwash pump, the backwash pressure gauge, the electromagnetic flowmeter, the backwash valve, the water supplementing valve, the water production pressure gauge, the blower and the plurality of pneumatic butterfly valves are all connected with the membrane pool control system;
referring to fig. 1, the intelligent cleaning method of the MBR membrane bioreactor comprises the following steps:
step1: the first evacuation of the cleaning membrane tank (membrane tank to be cleaned); in a Step1 stage in the prior art, the ultrasonic liquid level meter is easy to be interfered by foam when the liquid level is low, so that the liquid level detection is inaccurate, the evacuation pump is dry rotated, and the evacuation pump is damaged;
in the primary emptying stage of the cleaning membrane pool, firstly, the liquid level starts to be emptied and counted down, and the emptying state does not reach a stable state due to gas and the like in a pipeline in the initial stage of the emptying, so that a time point t1 is taken to record the liquid level H1 at the time t1, wherein the time t1 is more than or equal to 1 (unit: min); when the time t2 is reached after a period of time, recording the liquid level H2 at the time t2, wherein t2-t1 is more than or equal to 5 and less than or equal to 8 (unit: min), and according to multiple emptying experiences, the detection of an ultrasonic liquid level meter is accurate for ten minutes before emptying;
and calculating the draining time t according to the draining algorithm:
the relation between the starting liquid level of the membrane pool emptying and the time is as follows: h=kt+b, see fig. 4;
wherein:
k is the slope of the straight line in the above graph;
b is the initial liquid level of the membrane Chi Paikong;
thus, from time t2, the evacuation time t required for evacuation is:
(t is the time required for evacuation);
according to the calculation result, 5 minutes before the evacuation pump stops, starting the backwash pump, opening the backwash valve and closing the water replenishing valve;
the dry running phenomenon of the evacuation pump caused by abnormal monitoring of the ultrasonic liquid level meter is avoided by adopting the evacuation method; simultaneously, in order to achieve the purpose of reducing the sludge content in the membrane tank as much as possible after the membrane tank is emptied, 5 minutes before the emptying pump is stopped, the backwash pump is started, the backwash valve is opened, and the water supplementing valve is closed, wherein the purpose of the process is to wash the membrane filaments from inside to outside through backwash action, remove the sludge on the outer surface of the membrane filaments, and simultaneously wash the residual sludge in the membrane tank;
step2: supplementing water, aerating and reversely cleaning the cleaning membrane pool;
in the stage, firstly, the membrane tank to be cleaned is supplemented with water, in the water supplementing process of the membrane tank to be cleaned, the closing and opening alternating actions of a circulating water supplementing valve are repeated to play a role in backwashing the membrane tank to be cleaned, meanwhile, in order to improve the cleaning effect, a pneumatic butterfly valve of an aeration system, which is positioned on an aeration branch pipe outside the membrane tank to be cleaned, is closed, and the pneumatic butterfly valve on the aeration branch pipe connected with the membrane tank to be cleaned is opened, so that the aeration branch pipe connected with the membrane tank to be cleaned is communicated with an air blower, and the air blower is used for aerating the membrane tank to be cleaned in a parallel connection mode through the aeration branch pipe, so that the aeration quantity in the membrane tank to be cleaned is increased, and the figure 3 is shown;
in this stage, the aeration rate in the cleaning membrane tank is mainly increased to rinse off the filter cake layer on the membrane filaments, and to meet this requirement, first: the liquid level of the clean water in the cleaning membrane pool is required; second,: the aeration butterfly valve needs to perform corresponding actions;
the clean water level requirement of the cleaning membrane tank is as follows: the clean water level of the cleaning membrane tank is about 10 cm lower than the other membrane tanks; to reduce the water pressure of the cleaning membrane tank to increase the air flow rate of the cleaning membrane tank;
the requirements for the aeration butterfly valve are as follows: in the full water aeration stage of the cleaning membrane tank, the backwash pump works for 1 minute every 5 minutes; back flushing the membrane wires from inside to outside through a back flushing pipeline;
meanwhile, the pressure value of the backwashing pipeline is compared with the standard pressure value, and the reagent adding concentration and the reagent soaking time required in the Step4 stage are timely adjusted, wherein the pressure value of the backwashing pipeline is a value read from a backwashing pressure gauge;
step3: cleaning the membrane pool for the second time;
repeating Step1 to drain the cleaning membrane tank for the second time after the clear water soaking and aeration time in the Step2 reaches 30 minutes;
step4: supplementing water, adding medicine, soaking, aerating and back-cleaning in a cleaning membrane tank;
firstly, supplementing water into a cleaning membrane pool, adding a medicament while supplementing water, and soaking after the water supplementing is finished, wherein the soaking time calculated in the Step2 stage is regulated according to the pressure on a backwashing pipeline in the water supplementing process;
in this stage, need open backwash pump, backwash valve, moisturizing valve and carry out the moisturizing, the liquid level in cleaning membrane pond needs to reach La, wherein:
L N the liquid level of each membrane pool;
la: setting the highest liquid level in cleaning;
after 15 minutes of dosing and soaking, the soaking time is calculated according to the backwashing pressure displayed on a backwashing pressure gauge, and the specific steps are as follows:
(1) Closing a water supplementing valve, opening a backwashing valve and opening a backwashing pump, so that the backwashing pump runs at a fixed frequency f, collecting pressure data Ptrans 1 (unit: kpa) of a backwashing pressure gauge after the backwashing pump runs for 20 seconds, closing the backwashing pump after the backwashing pump runs for 25 seconds, wherein Ptrans 1 is an average value of integral second data collected for 20-25 seconds;
(2) The soaking time is calculated according to the collected backwashing pressure, and the calculation method is as follows:
wherein, T1 is soaking time (unit: min);
ps: the standard pressure value (unit: kpa) is set, and the standard pressure value is the pressure of the last washing and the last back washing of the membrane pool and is used as the standard pressure value;
Ψ t : time coefficient (changing 1.ltoreq.ψ according to service life of membrane module) t 1≤10);
Γ t : aging coefficient of membrane module (increase of 0.ltoreq.Γ with increase of service life of membrane module) t ≤5);
F, cleaning the production of the membrane pool in the previous periodAverage flow (m) 3 /h)
Fit: running average frequency (Hz) of water pump produced in previous period of cleaning
In addition, T 1 The value range is as follows, T is 45-T 1 Less than or equal to 150; i.e. T when the calculated time is greater than 150 minutes by the formula 1 Taking 150 minutes;
(3) The membrane pool control system starts the detection of backwash pressure every 15 minutes and according to the value P of the backwash pressure gauge Inverse N And (3) calculating soaking time, wherein a calculation formula is as follows:
wherein T is N Detecting the calculated soaking time (unit: min) for the Nth time;
P inverse N The backwash pipeline pressure value detected by the backwash pressure gauge read in the Nth detection;
f, cleaning the water yield average flow (m) 3 /h)
Fit: running average frequency (Hz) of water pump produced in previous period of cleaning
N is the number of times of 2-8 (unit: min);
step5: cleaning the membrane pool for the third time;
when N is<8 and the detection result of two continuous backwashing is T N <At 15 (8-N), cleaning the membrane pool for three times, draining, entering step6, and normally producing water;
after the chemical adding soaking is completed, the membrane pool is continuously emptied, and a water inlet and outlet gate is opened to produce water;
when n=8 and T N When the pressure is more than or equal to 15, step4 ends the alarm informing action of the membrane pool control system; if T is calculated by 8 times of the above operations N If the immersion and backwashing of the membrane pool are finished and the expected effect is not achieved by the backwashing, a corresponding alarm informing action is made in the control system;
through the operation, the cleaning and soaking time of the membrane tank can be greatly shortened, and the cleaning efficiency of the membrane tank is improved.
After the cleaning method of the invention enters a cleaning mode, the emptying pump outside the membrane tank completely empties the cleaning membrane tank according to the emptying time calculated by the slope of the liquid level and the running time; according to parameters such as outlet pressure of a backwashing pipeline, a relation value of flow and frequency (water flow produced per unit frequency) before flow cleaning and the like in the water supplementing process, the soaking time after water supplementing is calculated; when the rest 5 minutes of the soaking procedure are reached, increasing the aeration quantity of the cleaning membrane pool; the method has the advantages that the backwashing is carried out every half hour during the dosing soaking period, the soaking time is calculated again according to the backwashing pressure, and the membrane components in the cleaning membrane tank can be effectively cleaned, so that the pollution of the membrane bioreactor is delayed, the cleaning time is shortened, and the water production efficiency is improved.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions of the prior art, the drawings which are required in the description of the embodiments or the prior art will be briefly described, it being obvious that the drawings in the description below are only some embodiments of the invention, and that other drawings can be obtained from these drawings without inventive faculty for a person skilled in the art.
FIG. 1 is a circuit diagram of the overall structure of an MBR membrane bioreactor involved in Step2 of an intelligent cleaning method of the MBR membrane bioreactor according to an embodiment of the present invention;
FIG. 2 is a circuit diagram of a single set of the MBR membrane bioreactor shown in FIG. 1;
FIG. 3 is a flow chart of an intelligent cleaning method for an MBR membrane bioreactor in an embodiment of the invention;
FIG. 4 is a graph of the start level of cleaning membrane pool emptying versus time in Step1 of the intelligent cleaning method of MBR membrane bioreactor shown in FIG. 1;
a, a water works; b, membrane pool water distribution channels; c, a membrane pool backflow channel; d, producing a water pump; e, cleaning a circulating emptying pump; f, adding a sodium hypochlorite pump into the restorative cleaning; g, restoring cleaning and adding a citric acid pump; h, maintainability cleaning and adding a sodium hypochlorite pump; i, maintenance cleaning and adding a citric acid pump; a membrane cell 1; an ultrasonic level gauge 11; a membrane module 12; an aeration system 2; a blower 21; an aeration branch pipe 22; a pneumatic butterfly valve 23; a backwash pipeline 3; a backwash valve 31; a water replenishment valve 32; a first branch backwash line 301; a second leg backwash line 302; a backwash pump 4; a backwash header 5; a backwash pressure gauge 51; an electromagnetic flowmeter 52; a water producing pipeline 6; a water production pressure gauge 61.
Detailed Description
The technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In a specific embodiment of the present invention, an intelligent cleaning method for an MBR membrane bioreactor, see fig. 1-2, includes:
the membrane tank 1 is internally provided with an ultrasonic liquid level meter 11 and an aeration system 2;
a membrane module 12 disposed in the membrane tank 1;
the back washing pump 4 is connected with a back washing main pipe 5, and the back washing main pipe 5 is connected with a back washing pipeline 3 for communication;
a backwash pressure gauge 51 and an electromagnetic flowmeter 52 are arranged on the backwash header pipe 5;
a first branch backwash pipeline 301 is communicated with the backwash pipeline 3, the first branch backwash pipeline is simultaneously communicated with the backwash main pipe 3 and the backwash main pipe 5, and a backwash valve 31 is arranged on the first branch backwash pipeline 301;
a second branch backwash pipeline 302 is communicated with the backwash pipeline 3, each second branch backwash pipeline 302 is communicated with the backwash pipeline 3 and the membrane tank 1, and a water supplementing valve 32 is arranged on the second branch backwash pipeline;
a water producing pipeline 6, wherein the water producing pipeline 6 is communicated with the membrane tank 1, and a water producing pressure gauge 61 is arranged on the water producing pipeline 6;
the aeration system 2 comprises a blower 21, a plurality of sets of aeration branch pipes 22 and a plurality of pneumatic butterfly valves 23, wherein the aeration branch pipes are communicated with the blower, one pneumatic butterfly valve is arranged on one aeration branch pipe, and the aeration branch pipe is communicated with the membrane tank;
the number of the membrane tanks is N, N is an integer, and N is more than or equal to 2;
m membrane modules are arranged in each membrane pool 1, and M is more than or equal to 1;
the water producing pipelines are provided with N water producing pipelines which are respectively communicated with the N membrane tanks;
the membrane pool control system comprises an ultrasonic liquid level meter, a membrane assembly, a backwash pump, a backwash pressure gauge, an electromagnetic flowmeter, a backwash valve, a water supplementing valve, a water production pressure gauge, a blower and a plurality of pneumatic butterfly valves, wherein the ultrasonic liquid level meter, the membrane assembly, the backwash pump, the backwash pressure gauge, the electromagnetic flowmeter, the backwash valve, the water supplementing valve, the water production pressure gauge, the blower and the plurality of pneumatic butterfly valves are all connected with the membrane pool control system;
referring to fig. 1, the intelligent cleaning method of the MBR membrane bioreactor comprises the following steps:
step1: the first evacuation of the cleaning membrane tank (membrane tank to be cleaned); in a Step1 stage in the prior art, the ultrasonic liquid level meter is easy to be interfered by foam when the liquid level is low, so that the liquid level detection is inaccurate, the evacuation pump is dry rotated, and the evacuation pump is damaged;
in the primary emptying stage of the cleaning membrane pool, firstly, the liquid level starts to be emptied and counted down, and the emptying state does not reach a stable state due to gas and the like in a pipeline in the initial stage of the emptying, so that a time point t1 is taken to record the liquid level H1 at the time t1, wherein the time t1 is more than or equal to 1 (unit: min); when the time t2 is reached after a period of time, recording the liquid level H2 at the time t2, wherein t2-t1 is more than or equal to 5 and less than or equal to 8 (unit: min), and according to multiple emptying experiences, the detection of an ultrasonic liquid level meter is accurate for ten minutes before emptying;
and calculating the draining time t according to the draining algorithm:
the relation between the starting liquid level of the membrane pool emptying and the time is as follows: h=kt+b, see fig. 4;
wherein:
k is the slope of the line in FIG. 4;
b is the initial liquid level of the membrane Chi Paikong;
thus, from time t2, the evacuation time t required for evacuation is:
(t is the time required for evacuation);
according to the calculation result, 5 minutes before the evacuation pump stops, starting the backwash pump, opening the backwash valve and closing the water replenishing valve;
by adopting the above emptying method, the dry running phenomenon of the emptying pump caused by abnormal monitoring of the ultrasonic liquid level meter is avoided. Simultaneously, in order to achieve the purpose of reducing the sludge content in the membrane tank as much as possible after the membrane tank is emptied, 5 minutes before the emptying pump is stopped, the backwash pump is started, the backwash valve is opened, and the water supplementing valve is closed, wherein the purpose of the process is to wash the membrane filaments from inside to outside through backwash action, remove the sludge on the outer surface of the membrane filaments, and simultaneously wash the residual sludge in the membrane tank;
step2: supplementing water, aerating and reversely cleaning the cleaning membrane pool;
in the stage, firstly, the membrane tank to be cleaned is supplemented with water, in the water supplementing process of the membrane tank to be cleaned, the closing and opening alternating actions of a circulating water supplementing valve are repeated to play a role in backwashing the membrane tank to be cleaned, meanwhile, in order to improve the cleaning effect, a pneumatic butterfly valve of an aeration system, which is positioned on an aeration branch pipe outside the membrane tank to be cleaned, is closed, and the pneumatic butterfly valve on the aeration branch pipe connected with the membrane tank to be cleaned is opened, so that the aeration branch pipe connected with the membrane tank to be cleaned is communicated with an air blower, and the air blower is used for aerating the membrane tank to be cleaned in a parallel connection mode through the aeration branch pipe, so that the aeration quantity in the membrane tank to be cleaned is increased, and the figure 3 is shown;
in this stage, the aeration rate in the cleaning membrane tank is mainly increased to rinse off the filter cake layer on the membrane filaments, and to meet this requirement, first: the liquid level of the clean water in the cleaning membrane pool is required; second,: the aeration butterfly valve needs to perform corresponding actions;
the clean water level requirement of the cleaning membrane tank is as follows: the clean water level of the cleaning membrane tank is about 10 cm lower than the other membrane tanks; to reduce the water pressure of the cleaning membrane tank to increase the air flow rate of the cleaning membrane tank;
the requirements for the aeration butterfly valve are as follows: in the full water aeration stage of the cleaning membrane tank, the backwash pump works for 1 minute every 5 minutes; back flushing the membrane wires from inside to outside through a back flushing pipeline;
meanwhile, the pressure value of the backwashing pipeline is compared with the standard pressure value, and the reagent adding concentration and the reagent soaking time required in the Step4 stage are timely adjusted, wherein the pressure value of the backwashing pipeline is a value read from a backwashing pressure gauge;
step3: cleaning the membrane pool for the second time;
repeating Step1 to drain the cleaning membrane tank for the second time after the clear water soaking and aeration time in the Step2 reaches 30 minutes;
step4: supplementing water, adding medicine, soaking and back-cleaning in a cleaning membrane pool;
firstly, supplementing water into a cleaning membrane pool, adding a medicament while supplementing water, and soaking after the water supplementing is finished, wherein the soaking time calculated in the Step2 stage is regulated according to the pressure on a backwashing pipeline in the water supplementing process;
in this stage, need open backwash pump, backwash valve, moisturizing valve and carry out the moisturizing, the liquid level in cleaning membrane pond needs to reach La, wherein:
L N the liquid level of each membrane pool;
la: average liquid level of N membrane tanks;
after 15 minutes of dosing and soaking, the soaking time is calculated according to the backwashing pressure displayed on a backwashing pressure gauge, and the specific steps are as follows:
(1) Closing a water supplementing valve, opening a backwashing valve and opening a backwashing pump to enable the backwashing pump to operate at a fixed frequency f, and collecting pressure data P of a backwashing pressure gauge after the backwashing pump operates for 20 seconds Reverse 1 (unit: kpa), inverseAfter the washing pump operates for 25 seconds, the backwashing pump is turned off, and P Reverse 1 Is the average value of the integer second data of 20-25 seconds;
(2) The soaking time is calculated according to the collected backwashing pressure, and the calculation method is as follows:
wherein T is 1 Soaking time (unit: min);
ps: the standard pressure value (unit: kpa) is set, and the standard pressure value is the pressure of the last washing and the last back washing of the membrane pool and is used as the standard pressure value;
Ψ t : time coefficient (changing 1.ltoreq.ψ according to service life of membrane module) t 1≤10);
Γ t : aging coefficient of membrane module (increase of 0.ltoreq.Γ with increase of service life of membrane module) t ≤5);
F, cleaning the water yield average flow (m) 3 /h)
Fit: running average frequency (Hz) of water pump produced in previous period of cleaning
In addition, T 1 The value range is as follows, T is 45-T 1 Less than or equal to 150; i.e. T when the calculated time is greater than 150 minutes by the formula 1 Taking 150 minutes;
(3) The membrane pond control system starts the detection of backwash pressure every 15 minutes to carry out the calculation of soaking time according to the numerical value P of backwash pressure gauge against N, the computational formula is:
wherein T is N Detecting the calculated soaking time (unit: min) for the Nth time;
P inverse N The backwash pipeline pressure value detected by the backwash pressure gauge read in the Nth detection;
f, cleaning the water yield average flow (m) 3 /h)
Fit: running average frequency (Hz) of water pump produced in previous period of cleaning
N is the number of times of 2-8 (unit: min);
step5: cleaning the membrane pool for the third time;
when N is<8 and the detection result of two continuous backwashing is T N <At the time of 15 (8-N), cleaning the membrane pool for three times, and normally producing water;
after the chemical adding soaking is completed, the membrane pool is continuously emptied, and a water inlet and outlet gate is opened to produce water;
if the water inlet gate is directly opened to produce water, the concentration of the discharged water is higher, and in order to avoid the problem, the water is emptied for the third time so as to reduce the components of the medicament added in the sewage;
step6: normal water production;
when n=8 and T N When the pressure is more than or equal to 15, step4 ends the alarm informing action of the membrane pool control system; if T is calculated by 8 times of the above operations N If the immersion and backwashing of the membrane pool are finished and the expected effect is not achieved by the backwashing, a corresponding alarm informing action is made in the control system;
through the operation, the cleaning and soaking time of the membrane tank can be greatly shortened, and the cleaning efficiency of the membrane tank is improved.
The backwashing process in this application is: and opening the backwash pump under the condition of closing the water supplementing valve so that clean water enters the membrane tank through the membrane wires.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, alternatives, and improvements that fall within the spirit and scope of the invention.