A method and system for improving the water production rate of a membrane system

Abstract

The present invention belongs to the technical field of sewage treatment, and discloses a method and system for improving the water production rate of a membrane system. The method comprises the following steps: using the biological filter effluent water quality monitoring subsystem to monitor the water quality of the membrane system in real time; if the water quality of the produced water exceeds a threshold, using the ultrafiltration membrane pollution analysis subsystem to evaluate the membrane pollution, and formulating the operating parameters of the membrane workshop backwashing and dosing subsystem according to the evaluation results, and then backwashing the membrane assembly. The present invention evaluates the ultrafiltration membrane pollution analysis subsystem, and then formulates the operating parameters of the membrane workshop backwashing and dosing subsystem, and cooperates with the real-time monitoring of the biological filter effluent water quality monitoring subsystem, thereby achieving stable operation of the membrane system.

Description

Technical Field

[0001] The present invention belongs to the technical field of sewage treatment, and in particular, relates to a method and system for improving the water production rate of a membrane system. Background Art

[0002] At present, there is a serious shortage of freshwater resources. The effective way to solve this problem is to recycle domestic sewage, which is of great significance to alleviate the current situation of water shortage. Ultrafiltration membrane technology can effectively intercept particles in water with a particle size larger than the pore size of ultrafiltration membrane. It has the advantages of good water quality, small footprint, stable operation, easy automatic control, no phase change, and no secondary pollution. It has been widely used in the field of sewage recycling. However, during the long-term operation of the membrane, inorganic particles and colloidal viscous organic matter will accumulate on the membrane surface, and it is difficult to remove them with simple cleaning, gradually forming serious membrane pollution. In addition, defects in the membrane system and pretreatment design, human operation errors, extensive and delayed operation and maintenance management, etc. will aggravate the degree of membrane pollution. The decrease in membrane flux, increase in transmembrane pressure difference, and decrease in water quality caused by membrane fouling are the main problems faced during the operation of ultrafiltration process. However, with the continuous refinement of operation and management methods, it is necessary to conduct tests and evaluations through on-site sampling to seek more economical, reasonable and efficient cleaning methods, which is also of great significance to maintaining the stable operation of the system. Summary of the invention

[0003] The purpose of the present invention is to address the deficiencies of the prior art and propose a method and system for improving the water production rate of a membrane system. The present invention evaluates the ultrafiltration membrane pollution analysis subsystem, and then formulates the operating parameters of the membrane workshop backwash dosing subsystem, and cooperates with the real-time monitoring of the biofilter effluent water quality monitoring subsystem, thereby achieving stable operation of the membrane system.

[0004] In order to achieve the above-mentioned object, the present invention provides a system for improving the water production rate of a membrane system, which includes an ultrafiltration membrane pollution analysis subsystem, a biofilter effluent water quality monitoring subsystem, a membrane workshop backwashing and dosing subsystem, and a plurality of membrane components;

[0005] The membrane workshop backwashing and dosing subsystem includes multiple drug dosing rooms, multiple dosing pumps, multiple flow meters, multiple backwashing solenoid valves, multiple backwashing pumps, backwashing water reservoirs, CIP cleaning circulation pumps, CIP cleaning solenoid valves and CIP dosing tanks;

[0006] The multiple drug dosing rooms are respectively connected to one end of the multiple dosing pumps; the other end of each two of the multiple dosing pumps, one of the multiple flow meters, and one end of each two of the multiple backwash solenoid valves are connected in sequence; the other ends of the multiple backwash solenoid valves are respectively connected to the water inlet ends of the multiple backwash pumps; the water inlet ends of the multiple backwash pumps are also connected to the backwashing water reservoir; each two of the water outlet ends of the multiple backwash pumps are connected to one of the multiple membrane assemblies;

[0007] The other ends of the multiple dosing pumps are also connected to the CIP cleaning solenoid valve, the CIP cleaning circulation pump, and the multiple membrane components in sequence.

[0008] On one hand, the present invention provides a method for improving the water production rate of a membrane system. The method adopts the system for improving the water production rate of the membrane system, and comprises the following steps: using the biological filter effluent water quality monitoring subsystem to monitor the water quality of the membrane system in real time; if the water quality of the produced water exceeds a threshold, using the ultrafiltration membrane pollution analysis subsystem to evaluate the membrane pollution, and formulating the operating parameters of the membrane workshop backwashing and dosing subsystem according to the evaluation results, and then backwashing the membrane assembly, the steps comprising:

[0009] S1: backwashing the membrane assembly: sequentially opening the multiple backwash solenoid valves, multiple dosing pumps, and multiple backwash pumps to backwash the membrane assembly, and after the backwashing is completed, sequentially closing the multiple backwash pumps, multiple backwash solenoid valves, and multiple dosing pumps;

[0010] S2: Perform CIP cleaning on the membrane assembly: start the multiple dosing pumps, CIP cleaning solenoid valves, and CIP cleaning circulation pumps in sequence to perform CIP cleaning on the membrane assembly; after the CIP cleaning is completed, close the CIP cleaning circulation pump, CIP cleaning solenoid valves, and multiple dosing pumps in sequence.

[0011] The technical solution of the present invention has the following beneficial effects:

[0012] (1) The biofilter effluent water quality monitoring subsystem of the system of the present invention can ensure the stability of membrane system operation by sampling the effluent of the nitrification filter and the main channel in real time and performing online water quality monitoring.

[0013] (2) The present invention is based on the actual situation of each water plant, using the advanced instruments and detection methods of the ultrafiltration membrane pollution analysis subsystem to detect pollutants on the membrane surface and restore the membrane performance through different cleaning schemes, and proposes corresponding control strategies based on data analysis.

[0014] (3) The present invention transforms the existing membrane workshop backwashing and dosing system according to the analysis results of the ultrafiltration membrane pollution analysis subsystem, re-establishes the operating parameters, realizes the backwashing process accompanied by low-concentration sodium hypochlorite cleaning, alleviates the pollution of the ultrafiltration membrane, prolongs the backwashing self-cleaning filter cleaning cycle and the ultrafiltration membrane chemical cleaning cycle, ensures the stable operation of the membrane system (especially when the membrane system is added with carbon source in the front-end biological filter in winter), reduces the membrane system permeability attenuation rate, and improves the membrane system recovery rate and water production. That is, the membrane workshop water production is increased from an average of 70,000 m per day to 10,000 m per day. 3 / d increased to 95,000 m 3 / d.

[0015] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention in conjunction with the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present invention.

[0017] Figure 1 A schematic diagram of a water quality monitoring subsystem for the effluent from a biofilter of a system for improving the water production rate of a membrane system provided in Example 1 of the present invention is shown.

[0018] Figure 2 A schematic diagram of a membrane workshop backwashing and dosing subsystem and multiple membrane components of a system for improving the water production rate of a membrane system provided in Example 1 of the present invention is shown.

[0019] Figure 3 A microscopic morphology diagram of a membrane component for observing the membrane surface morphology in a method for improving the water production rate of a membrane system provided in Example 2 of the present invention is shown.

[0020] Figure 4 A graph showing the changes in inlet and outlet water production before and after treatment using a method for improving the water production rate of a membrane system provided in Example 2 of the present invention is shown.

[0021] The following are the descriptions of the reference numerals:

[0022] 1-drug dosing room; 2-dosing pump; 3-flow meter; 4-backwash solenoid valve; 5-backwash pump; 6-backwash reservoir; 7-CIP cleaning circulation pump; 8-CIP cleaning solenoid valve; 9-CIP dosing tank; 10-membrane assembly; 11-filter outlet main channel; 12-nitrification filter; 13-main channel inlet pump; 14-other inlet pumps; 15-main channel turbidity detection unit; 16-other turbidity detection units. DETAILED DESCRIPTION

[0023] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.

[0024] On one hand, the present invention provides a system for improving the water production rate of a membrane system, the system comprising an ultrafiltration membrane pollution analysis subsystem, a biofilter effluent water quality monitoring subsystem, a membrane workshop backwashing and dosing subsystem, and a plurality of membrane components;

[0025] The membrane workshop backwashing and dosing subsystem includes multiple drug dosing rooms, multiple dosing pumps, multiple flow meters, multiple backwashing solenoid valves, multiple backwashing pumps, backwashing water reservoirs, CIP cleaning circulation pumps, CIP cleaning solenoid valves and CIP dosing tanks;

[0026] The multiple drug dosing rooms are respectively connected to one end of the multiple dosing pumps; the other end of each two of the multiple dosing pumps, one of the multiple flow meters, and one end of each two of the multiple backwash solenoid valves are connected in sequence; the other ends of the multiple backwash solenoid valves are respectively connected to the water inlet ends of the multiple backwash pumps; the water inlet ends of the multiple backwash pumps are also connected to the backwashing water reservoir; each two of the water outlet ends of the multiple backwash pumps are connected to one of the multiple membrane assemblies;

[0027] The other ends of the multiple dosing pumps are also connected to the CIP cleaning solenoid valve, the CIP cleaning circulation pump, and the multiple membrane components in sequence.

[0028] In the present invention, the bottoms of the plurality of drug dosing rooms are respectively connected to one end of the plurality of drug dosing pumps.

[0029] In the present invention, the CIP (clean in place) cleaning is cleaning in place.

[0030] In the present invention, as a preferred embodiment, the number of the drug dosing room, the drug dosing pump, the backwash solenoid valve, and the backwash pump are four; the number of the membrane assembly is two; and the number of the flow meter is two.

[0031] According to the present invention, preferably, the biological filter effluent water quality monitoring subsystem includes a filter effluent main channel, multiple nitrification filters, multiple water inlet pumps and multiple turbidity detection units; the multiple water inlet pumps include a main channel inlet pump and multiple other water inlet pumps, and the multiple turbidity detection units include a main channel turbidity detection unit and multiple other turbidity detection units; the multiple nitrification filters, the multiple other water inlet pumps, and the multiple other turbidity detection units are connected in sequence; the filter effluent main channel, the main channel inlet pump, and the main channel turbidity detection units are connected in sequence.

[0032] In the present invention, as a preferred embodiment, the number of the other water inlet pumps, the nitrification filter tanks, and the other turbidity detection units are all four.

[0033] In the present invention, the plurality of nitrification filters are all connected to the filter outlet main channel.

[0034] According to the present invention, preferably, the turbidity detection units each include a circulating water tank and a turbidity meter.

[0035] In the present invention, the other water inlet pumps are connected to the turbidity meters of the other turbidity detection units; the main channel water inlet pump is connected to the turbidity meter of the main channel turbidity detection unit.

[0036] According to the present invention, preferably, the ultrafiltration membrane contamination analysis subsystem comprises a scanning electron microscope, an ICP-OES instrument, a three-dimensional fluorescence detector and a TOC detector.

[0037] On one hand, the present invention provides a method for improving the water production rate of a membrane system. The method adopts the system for improving the water production rate of the membrane system, and comprises the following steps: using the biological filter effluent water quality monitoring subsystem to monitor the water quality of the membrane system in real time; if the water quality of the produced water exceeds a threshold, using the ultrafiltration membrane pollution analysis subsystem to evaluate the membrane pollution, and formulating the operating parameters of the membrane workshop backwashing and dosing subsystem according to the evaluation results, and then backwashing the membrane assembly, the steps comprising:

[0038] S1: backwashing the membrane assembly: sequentially opening the multiple backwash solenoid valves, multiple dosing pumps, and multiple backwash pumps to backwash the membrane assembly, and after the backwashing is completed, sequentially closing the multiple backwash pumps, multiple backwash solenoid valves, and multiple dosing pumps;

[0039] S2: Perform CIP cleaning on the membrane assembly: start the multiple dosing pumps, CIP cleaning solenoid valves, and CIP cleaning circulation pumps in sequence to perform CIP cleaning on the membrane assembly; after the CIP cleaning is completed, close the CIP cleaning circulation pump, CIP cleaning solenoid valves, and multiple dosing pumps in sequence.

[0040] In the present invention, when step S1 of backwashing the membrane assembly is started, step S2 of CIP cleaning the membrane assembly is closed; when step S2 of CIP cleaning the membrane assembly is started, step S1 of backwashing the membrane assembly is closed, the purpose of which is to ensure the dosage of each step.

[0041] In the present invention, in step S1 of backwashing the membrane assembly, the dosing pump is started before the backwashing pump to ensure that the dosing pipeline is full of reagent when the backwashing pump is started. As a preferred embodiment, the dosing pump is started 5s before the backwashing pump.

[0042] According to the present invention, preferably, the step of using the biological filter effluent water quality monitoring subsystem to monitor the water quality of the membrane system production water includes using the main channel inlet pump to draw water from the filter effluent main channel and transport it to the main channel turbidity detection unit, and using the multiple other inlet pumps to draw water from the multiple nitrification filters respectively, and transport it to the multiple other turbidity detection units respectively.

[0043] According to the present invention, preferably, the threshold is adjusted according to the on-site conditions, preferably 9.5-10.5 NTU, and more preferably 10 NTU.

[0044] According to the present invention, preferably, the evaluation of membrane pollution performed by the ultrafiltration membrane pollution analysis subsystem includes analysis of membrane system pollutants, membrane fiber performance analysis and membrane system performance cleaning and recovery analysis.

[0045] According to the present invention, preferably, the analysis of pollutants in the membrane system includes membrane surface morphology observation, analysis of inorganic pollutants on the membrane surface and analysis of organic pollutants on the membrane surface.

[0046] According to the present invention, preferably, the step of observing the membrane surface morphology includes cleaning the membrane filament contaminants of the membrane assembly using hydrochloric acid and NaOH solution respectively, and using the scanning electron microscope to observe the microscopic morphology of the membrane assembly before cleaning, the membrane assembly after cleaning with hydrochloric acid, and the membrane assembly after cleaning with NaOH solution respectively.

[0047] According to the present invention, preferably, the step of analyzing inorganic pollutants on the membrane surface includes cleaning the membrane filament pollutants of the membrane assembly with hydrochloric acid and NaOH solutions respectively, and detecting the hydrochloric acid pollutant mixed solution and the NaOH pollutant mixed solution after cleaning respectively using the ICP-OES instrument.

[0048] According to the present invention, preferably, the step of analyzing the organic pollutants on the membrane surface includes cleaning the membrane filament pollutants of the membrane assembly with hydrochloric acid and NaOH solution respectively, detecting the types of organic pollutants in the membrane assembly cleaned with hydrochloric acid and the types of organic pollutants in the membrane assembly cleaned with NaOH solution respectively using the three-dimensional fluorescence detector, and detecting the content of organic pollutants in the membrane assembly cleaned with hydrochloric acid and the content of organic pollutants in the membrane assembly cleaned with NaOH solution respectively using a TOC detector.

[0049] According to the present invention, preferably, the membrane filament performance analysis includes analysis of contact angle, tensile force at break, tensile strength at break, deformation and elongation at break.

[0050] According to the present invention, preferably, the contact angle analysis step includes cleaning the membrane fiber contaminants of the membrane assembly using NaClO solution and citric acid solution respectively, and detecting the contact angles of the membrane assembly before cleaning, the membrane assembly after cleaning with NaClO solution, and the membrane assembly after cleaning with citric acid solution respectively.

[0051] According to the present invention, preferably, the concentration of the NaClO solution is 2500-3500 ppm, the mass percentage of citric acid in the citric acid solution is 1-3%, and the cleaning time of the NaClO solution and the citric acid solution is 3-5 h.

[0052] According to the present invention, preferably, the step of analyzing the cleaning and recovery of the membrane system performance includes cleaning the membrane fiber contaminants of the membrane assembly with an acid-base combination agent, and comparing the membrane flux before and after cleaning.

[0053] According to the present invention, preferably, the acid-base solution combination agent is a combination of NaClO solution + citric acid solution, a combination of NaClO solution + oxalic acid solution, or a combination of NaClO solution + NaOH solution + oxalic acid solution; in each acid-base combination, the concentration of the NaClO solution is 2500-3500ppm, the mass percentage of citric acid in the citric acid solution is 1-3%, and the mass percentage of oxalic acid in the oxalic acid solution is 1-3%.

[0054] According to the present invention, preferably, the step of cleaning the membrane fiber contaminants of the membrane assembly using an acid-base combination agent includes sequentially cleaning the membrane fiber contaminants of the membrane assembly using an alkaline solution agent and an acid solution agent, and the cleaning time of each solution agent is 3-5 hours.

[0055] According to the present invention, preferably, the operating parameters of the membrane workshop backwashing and dosing subsystem are: the drug in the drug dosing room is NaClO solution, and the concentration of the NaClO solution is 0-50ppm; the flow rate of each NaClO solution is 650-750L / h, the backwashing time is 20-40min, the backwashing number of step 1 is 36-72 times / day, and the daily amount of NaClO for backwashing each membrane component is 2.4-2.8m 3 .

[0056] According to the present invention, preferably, the CIP cleaning time of step 2 is 90-180 min, the CIP cleaning of step 2 is performed every three days, and the amount of NaClO used for backwashing each membrane component is 2500 ppm.

[0057] The present invention is specifically described below by way of examples.

[0058] In the following examples, the ultrafiltration membrane was purchased from Beijing OriginWater Membrane Technology Co., Ltd.

[0059] Example 1

[0060] This embodiment provides a system for improving the water production rate of a membrane system, such as Figure 1 , Figure 2 As shown, the system includes an ultrafiltration membrane pollution analysis subsystem, a biofilter effluent water quality monitoring subsystem, a membrane workshop backwashing and dosing subsystem, and two membrane modules 10;

[0061] The membrane workshop backwashing and dosing subsystem includes four drug dosing rooms 1, four dosing pumps 2, two flow meters 3, four backwashing solenoid valves 4, four backwashing pumps 5, a backwashing reservoir 6, a CIP cleaning circulation pump 7, a CIP cleaning solenoid valve 7 and a CIP dosing tank 9;

[0062] The four drug dosing rooms 1 are respectively connected to one end of the four dosing pumps 2; the other end of every two dosing pumps 2, a flow meter 3, and one end of every two backwash solenoid valves 4 are connected in sequence; the other end of the four backwash solenoid valves 4 are respectively connected to the water inlet ends of the four backwash pumps 5; the water inlet ends of the four backwash pumps 5 are also connected to the backwashing water reservoir 6; every two water outlet ends of the four backwash pumps 5 are connected to a membrane assembly 10;

[0063] The other ends of the four dosing pumps 2 are also connected to the CIP cleaning solenoid valve 8 , the CIP cleaning circulation pump 7 , and the plurality of membrane assemblies 10 in sequence.

[0064] The biological filter effluent water quality monitoring subsystem includes a filter effluent main channel 11, four nitrification filters 12, five water inlet pumps and five turbidity detection units; the five water inlet pumps include a main channel inlet pump 13 and four other water inlet pumps 14, and the five turbidity detection units include a main channel turbidity detection unit 15 and four other turbidity detection units 16; the four nitrification filters 12, the four other water inlet pumps 14, and the four other turbidity detection units 16 are connected in sequence; the filter effluent main channel 11, the main channel inlet pump 13, and the main channel turbidity detection unit 15 are connected in sequence;

[0065] The turbidity detection units all include a circulating water tank and a turbidity meter, neither of which are shown in the figure.

[0066] The ultrafiltration membrane pollution analysis subsystem includes a scanning electron microscope, an ICP-OES instrument, a three-dimensional fluorescence detector and a TOC detector, which are not shown in the figure.

[0067] Example 2

[0068] The present embodiment provides a method for improving the water production rate of a membrane system. The method adopts the system for improving the water production rate of a membrane system described in Example 1, and comprises the following steps: using the biofilter effluent water quality monitoring subsystem to monitor the water quality of the membrane system water in real time; if the water quality of the water production exceeds a threshold, using the ultrafiltration membrane pollution analysis subsystem to evaluate the membrane pollution, and formulating the operating parameters of the membrane workshop backwashing and dosing subsystem according to the evaluation results, and then backwashing the membrane assembly. The steps include:

[0069] S1: backwashing the membrane assembly: sequentially opening the four backwashing solenoid valves 4, the four dosing pumps 2, and the four backwashing pumps 5 to backwash the membrane assembly, and after the backwashing is completed, sequentially closing the four backwashing pumps 5, the four backwashing solenoid valves 4, and the four dosing pumps 2;

[0070] S2: Perform CIP cleaning on the membrane assembly: turn on the four dosing pumps 2, the CIP cleaning solenoid valve 8, and the CIP cleaning circulation pump 7 in sequence to perform CIP cleaning on the membrane assembly; after the CIP cleaning is completed, turn off the CIP cleaning circulation pump 7, the CIP cleaning solenoid valve 8, and the four dosing pumps 2 in sequence.

[0071] In this embodiment, when step S1 of backwashing the membrane assembly is started, step S2 of CIP cleaning the membrane assembly is turned off; when step S2 of CIP cleaning the membrane assembly is started, step S1 of backwashing the membrane assembly is turned off. In step S1 of backwashing the membrane assembly, the dosing pump is started 5s before the backwashing pump.

[0072] The step of using the biological filter effluent water quality monitoring subsystem to monitor the water quality of the membrane system production water includes using the main channel inlet pump to take water from the filter effluent main channel and transport it to the main channel turbidity detection unit, using the multiple other inlet pumps to take water from the multiple nitrification filters respectively and transport it to the multiple other turbidity detection units respectively;

[0073] The threshold value is 10 NTU.

[0074] The evaluation of membrane pollution by the ultrafiltration membrane pollution analysis subsystem includes analysis of membrane system pollutants, membrane fiber performance analysis and membrane system performance cleaning and recovery analysis.

[0075] The analysis of the membrane system pollutants includes membrane surface morphology observation, membrane surface inorganic pollutant analysis and membrane surface organic pollutant analysis;

[0076] The step of observing the membrane surface morphology comprises cleaning the membrane filament contaminants of the membrane assembly with hydrochloric acid and NaOH solution respectively, and observing the microscopic morphology of the membrane assembly before cleaning, the membrane assembly after cleaning with hydrochloric acid, and the membrane assembly after cleaning with NaOH solution respectively with the scanning electron microscope, such as Figure 3 As shown, from Figure 3 It can be found that there are a large number of pollutants on the surface of the membrane assembly before cleaning (uncleaned original membrane). After cleaning, some of the blocked membrane pores are restored. The effect of cleaning with NaOH solution is better. Therefore, it is believed that when backwashing the membrane assembly, the membrane pore recovery effect will be better if the acid-base alternating cleaning method is adopted.

[0077] The step of analyzing inorganic pollutants on the membrane surface includes cleaning the membrane filament pollutants of the membrane assembly with hydrochloric acid and NaOH solutions respectively, and detecting the hydrochloric acid pollutant mixed solution and the NaOH pollutant mixed solution after cleaning respectively with the ICP-OES instrument. The detection results are shown in Table 1. Through the ICP-OES analysis, it can be found that the membrane filament pollutants include Ca, Fe, Al and Mn elements, and the concentration of metal elements in the hydrochloric acid pollutant mixed solution is higher than the concentration of metal elements in the NaOH pollutant mixed solution. The effect of acid washing is better than that of alkaline washing.

[0078] Table 1 Analysis of inorganic pollutants on membrane surface

[0079]

[0080] The steps of analyzing the organic pollutants on the membrane surface include respectively cleaning the membrane filament pollutants of the membrane assembly with hydrochloric acid and NaOH solution, respectively detecting the types of organic pollutants of the membrane assembly cleaned with hydrochloric acid and the types of organic pollutants of the membrane assembly cleaned with NaOH solution with the three-dimensional fluorescence detector, respectively detecting the contents of organic pollutants of the membrane assembly cleaned with hydrochloric acid and the contents of organic pollutants of the membrane assembly cleaned with NaOH solution with a TOC detector, and the test results are shown in Tables 2 and 3. It can be seen from the TOC and three-dimensional fluorescence results that the organic pollutants on the membrane filament surface are mainly proteins and microbial metabolites, and the contents of chemically cleanable organic pollutants are: 1670 mg / m 2 and 2016mg / m 2 , indicating that there are a large number of organic pollutants attached to the membrane surface, and alkaline washing is better than acid washing.

[0081] Table 2 Analysis of organic pollutants (3D fluorescence)

[0082] Cleaning agent ⅠProtein 1 II Protein 2 ⅢFulvic acid Ⅳ Microbial Metabolites Ⅴ Humic acid hydrochloric acid 39.01％ 21.79％ 16.64％ 14.45％ 8.11％ Sodium hydroxide 17.36％ 25.31％ 10.57％ 35.00％ 11.74％

[0083] Table 3 Analysis of organic pollutant content (TOC)

[0084]

[0085]

[0086] The membrane performance analysis includes analysis of contact angle, tensile force at break, tensile strength at break, deformation and elongation at break;

[0087] The contact angle analysis step includes cleaning the membrane fiber contaminants of the membrane assembly with NaClO solution and citric acid solution, respectively, and detecting the contact angles of the membrane assembly before cleaning, the membrane assembly after cleaning with NaClO solution, and the membrane assembly after cleaning with citric acid solution, respectively. The test results are shown in Table 4.1. The concentration of the NaClO solution is 3000ppm, the mass percentage of citric acid in the citric acid solution is 2%, and the cleaning time of the NaClO solution and the citric acid solution is 4h. As shown in Table 4.1, the contaminants are gradually removed and the hydrophilicity is gradually improved. As shown in Table 4.2, the average tensile force at break of the membrane assembly before and after cleaning is 2.71N, which is the mechanical property of conventional wet ultrafiltration membrane fibers.

[0088] Table 4.1 Membrane performance analysis

[0089] Membrane Module Contact Angle Before cleaning 92.4 Soak in NaClO (3000ppm) for 4h 94.2 Soak in citric acid (2%) for 4 hours 87.3

[0090] Table 4.2 Membrane performance analysis

[0091] Membrane Module Breaking tensile strength (N) Tensile strength at break (MPa) Deformation(mm) Elongation at break average value 2.71 2.87 106.95 71％

[0092] The step of cleaning and restoring the performance of the membrane system includes cleaning the membrane fiber contaminants of the membrane assembly with an acid-base combination agent, and comparing the membrane flux before and after cleaning;

[0093] This embodiment uses three acid-base solution combination agents for cleaning, namely, cleaning solution 1 of NaClO solution + citric acid solution combination, cleaning solution 2 of NaClO solution + oxalic acid solution combination, and cleaning solution 3 of NaClO solution + NaOH solution + oxalic acid solution combination; in each acid-base combination, the concentration of the NaClO solution is 3000ppm, the mass percentage of citric acid in the citric acid solution is 2%, and the mass percentage of oxalic acid in the oxalic acid solution is 2%;

[0094] The step of cleaning the membrane fiber contaminants of the membrane assembly by using an acid-base combination agent comprises cleaning the membrane fiber contaminants of the membrane assembly by using an alkaline solution agent and an acid solution agent in sequence, and the cleaning time of each solution agent is 4 hours;

[0095] The membrane flux results after cleaning with the above cleaning schemes 1, 2, and 3 are shown in Table 5. It can be seen from Table 5 that the membrane flux before cleaning is about 50LMH. The effect is better after cleaning with sodium hypochlorite, and the flux is restored to about 150LMH. After cleaning with citric acid, the flux is restored to about 270LMH. It can be seen that the membrane filaments under long-term accumulated pollution are seriously polluted by organic and inorganic pollution. As shown in Table 5, this embodiment mainly refers to the flux multiples after cleaning compared with before cleaning, that is, the average flux change.

[0096] Table 5 Membrane flux results after cleaning

[0097]

[0098]

[0099] According to the above results, the operating parameters of the membrane workshop backwashing and dosing subsystem are proposed as follows: the drug in the drug dosing room is NaClO solution, and the concentration of the NaClO solution is 50ppm; the flow rate of each NaClO solution is 700L / h, the backwashing time is 30min, the backwashing frequency of step 1 is 48 times / day, and the daily amount of NaClO for backwashing each membrane component is 2.6m 3 ;

[0100] The CIP cleaning time of step 2 is 90-180 minutes. The CIP cleaning of step 2 is performed every three days. The amount of NaClO used for backwashing each membrane component is 2500ppm.

[0101] The water production of the membrane workshop after backwashing the membrane assembly is changed as follows: Figure 4 As shown in the figure, the water production of the membrane workshop before the dotted line (i.e., the position close to the ordinate) is the water production of the membrane workshop without backwashing, and the water production of the membrane workshop after the dotted line (i.e., the position far from the ordinate) is the water production of the membrane workshop after backwashing. Figure 4 It can be seen that the ordinate represents the water production of the membrane workshop, and the abscissa represents time. After backwashing using the method of this embodiment, the water production of the membrane workshop increased from an average of 70,000 m3 per day to 3 / d increased to 110,000 m 3 / d.

[0102] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for improving the water production rate of a membrane system, characterized in that: The system used in this method to improve the water production rate of the membrane system includes an ultrafiltration membrane pollution analysis subsystem, a biofilter effluent water quality monitoring subsystem, a membrane workshop backwashing and dosing subsystem, and multiple membrane components; The membrane workshop backwashing and dosing subsystem includes multiple drug dosing rooms, multiple dosing pumps, multiple flow meters, multiple backwashing solenoid valves, multiple backwashing pumps, backwashing water reservoirs, CIP cleaning circulation pumps, CIP cleaning solenoid valves and CIP dosing tanks; The multiple drug dosing rooms are respectively connected to one end of the multiple dosing pumps; the other end of each two of the multiple dosing pumps, one of the multiple flow meters, and one end of each two of the multiple backwash solenoid valves are connected in sequence; the other ends of the multiple backwash solenoid valves are respectively connected to the water inlet ends of the multiple backwash pumps; the water inlet ends of the multiple backwash pumps are also connected to the backwashing water reservoir; each two of the water outlet ends of the multiple backwash pumps are connected to one of the multiple membrane assemblies; The other ends of the multiple dosing pumps are also connected to the CIP cleaning solenoid valve, the CIP cleaning circulation pump, and the multiple membrane components in sequence; The biological filter effluent water quality monitoring subsystem comprises a filter effluent main channel, a plurality of nitrification filters, a plurality of water inlet pumps and a plurality of turbidity detection units; the plurality of water inlet pumps comprises a main channel inlet pump and a plurality of other water inlet pumps, the plurality of turbidity detection units comprises a main channel turbidity detection unit and a plurality of other turbidity detection units; the plurality of nitrification filters, the plurality of other water inlet pumps and the plurality of other turbidity detection units are connected in sequence; the filter effluent main channel, the main channel inlet pump and the main channel turbidity detection unit are connected in sequence; The ultrafiltration membrane pollution analysis subsystem includes a scanning electron microscope, an ICP-OES instrument, a three-dimensional fluorescence detector and a TOC detector; The method comprises the following steps: using the biofilter effluent water quality monitoring subsystem to monitor the water quality of the membrane system in real time; if the water quality of the produced water exceeds a threshold, using the ultrafiltration membrane pollution analysis subsystem to evaluate the membrane pollution; and formulating the operating parameters of the membrane workshop backwashing and dosing subsystem according to the evaluation results, and then backwashing the membrane assembly, the steps comprising: S1: backwashing the membrane assembly: sequentially opening the multiple backwash solenoid valves, multiple dosing pumps, and multiple backwash pumps to backwash the membrane assembly, and after the backwashing is completed, sequentially closing the multiple backwash pumps, multiple backwash solenoid valves, and multiple dosing pumps; S2: Perform CIP cleaning on the membrane assembly: sequentially open the multiple dosing pumps, CIP cleaning solenoid valves, and CIP cleaning circulation pumps to perform CIP cleaning on the membrane assembly; after the CIP cleaning is completed, sequentially close the CIP cleaning circulation pump, CIP cleaning solenoid valves, and multiple dosing pumps; The step of using the biological filter effluent water quality monitoring subsystem to monitor the water quality of the membrane system production water includes using the main channel inlet pump to take water from the filter effluent main channel and transport it to the main channel turbidity detection unit, using the multiple other inlet pumps to take water from the multiple nitrification filters respectively and transport it to the multiple other turbidity detection units respectively; The evaluation of membrane pollution by the ultrafiltration membrane pollution analysis subsystem includes analysis of membrane system pollutants, membrane fiber performance analysis and membrane system performance cleaning and recovery analysis; The analysis of the membrane system pollutants includes membrane surface morphology observation, membrane surface inorganic pollutant analysis and membrane surface organic pollutant analysis; The step of observing the membrane surface morphology comprises cleaning the membrane filament contaminants of the membrane assembly with hydrochloric acid and NaOH solution respectively, and observing the microscopic morphology of the membrane assembly before cleaning, the membrane assembly after cleaning with hydrochloric acid, and the membrane assembly after cleaning with NaOH solution respectively with the scanning electron microscope; The step of analyzing inorganic pollutants on the membrane surface comprises cleaning the membrane filament pollutants of the membrane assembly with hydrochloric acid and NaOH solutions respectively, and detecting the hydrochloric acid pollutant mixed solution and the NaOH pollutant mixed solution after cleaning respectively with the ICP-OES instrument; The step of analyzing the organic pollutants on the membrane surface comprises cleaning the membrane fiber pollutants of the membrane assembly with hydrochloric acid and NaOH solution respectively, detecting the types of organic pollutants of the membrane assembly cleaned with hydrochloric acid and the types of organic pollutants of the membrane assembly cleaned with NaOH solution respectively with the three-dimensional fluorescence detector, and detecting the contents of organic pollutants of the membrane assembly cleaned with hydrochloric acid and the contents of organic pollutants of the membrane assembly cleaned with NaOH solution respectively with a TOC detector; The membrane performance analysis includes analysis of contact angle, tensile force at break, tensile strength at break, deformation and elongation at break; The contact angle analysis step includes cleaning the membrane fiber contaminants of the membrane assembly with a NaClO solution and a citric acid solution, respectively, and detecting the contact angles of the membrane assembly before cleaning, the membrane assembly after cleaning with a NaClO solution, and the membrane assembly after cleaning with a citric acid solution, respectively; The concentration of the NaClO solution is 2500-3500 ppm, the mass percentage of citric acid in the citric acid solution is 1-3%, and the cleaning time of the NaClO solution and the citric acid solution is 3-5 hours; The step of cleaning and restoring the performance of the membrane system includes cleaning the membrane fiber contaminants of the membrane assembly with an acid-base combination agent, and comparing the membrane flux before and after cleaning; The acid-base combination agent is a combination of NaClO solution + citric acid solution, a combination of NaClO solution + oxalic acid solution, or a combination of NaClO solution + NaOH solution + oxalic acid solution; in each acid-base combination, the concentration of the NaClO solution is 2500-3500ppm, the mass percentage of citric acid in the citric acid solution is 1-3%, and the mass percentage of oxalic acid in the oxalic acid solution is 1-3%; The step of using an acid-base combination agent to clean the membrane fiber contaminants of the membrane assembly comprises using an alkaline solution agent and an acid solution agent to clean the membrane fiber contaminants of the membrane assembly in sequence, and the cleaning time of each solution agent is 3-5 hours; The operating parameters of the membrane workshop backwashing and dosing subsystem are as follows: the drug in the drug dosing room is NaClO solution, and the concentration of the NaClO solution is 0-50ppm; the flow rate of each NaClO solution is 650-750L / h, the backwashing time is 20-40min, the backwashing frequency of step 1 is 36-72 times / day, and the daily amount of NaClO for backwashing each membrane component is 2.4-2.8m 3 ; The CIP cleaning time of step 2 is 90-180 min. The CIP cleaning of step 2 is performed every three days. The amount of NaClO used for backwashing each membrane component is 2500 ppm.

2. The method for improving the water production rate of a membrane system according to claim 1, wherein: The turbidity detection units all include a circulating water tank and a turbidity meter.

3. The method for improving the water production rate of a membrane system according to claim 1, wherein: The threshold value is 9.5-10.5 NTU.

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