A kitchen waste membrane separation device and automatic online membrane cleaning method

Abstract

The present invention relates to the field of membrane treatment technology, and in particular to a restaurant kitchen waste membrane separation device and an automatic online membrane cleaning method, which mainly include a hollow fiber membrane, a gas collection bag, a constant temperature water bath layer, a filtration pump, a biogas circulation pump, a transmembrane pressure difference sensor, and an automatic cleaning controller. The membrane filaments are aerated and shaken by the biogas circulation pump, and biogas is collected by the gas collection bag; the filtration pressure data is recorded based on the transmembrane pressure difference sensor to obtain the degree of membrane contamination, and the automatic cleaning controller is used to automatically add sodium hypochlorite cleaning agent to remove organic pollutants on the membrane, and the automatic cleaning controller is used to automatically add citric acid or oxalic acid and other cleaning agents to remove inorganic pollutants on the membrane. In addition, the cleaning cycle can be automatically solved for different fermentation liquid concentrations. The processing device and the solution method can promote the efficient and sustainable operation of the anaerobic membrane treatment device in the solid-liquid separation process of restaurant kitchen waste.

Description

Technical Field

[0001] The invention relates to the field of membrane separation, and in particular to a kitchen waste membrane separation device and an automatic online membrane cleaning method. Background Art

[0002] Since the garbage classification, the amount of wet garbage separated, mainly food waste, has increased greatly, and the difficulty of treatment has increased. In recent years, anaerobic membrane separation devices have been favored by researchers in the field of food waste treatment. They not only improve the stability of anaerobic fermentation, but also reduce the difficulty of back-end sludge treatment due to the improvement of membrane effluent water quality.

[0003] As an efficient anaerobic treatment technology for organic waste that can separate sludge retention time and hydraulic retention time, anaerobic membrane separation device is one of the mainstream treatment technologies in the field of solid-liquid separation, and has great application prospects in the treatment of food waste. However, due to the small pore size of the membrane (mostly 0.1~0.2 μm) and the fact that most of them are microfiltration membranes, the membrane surface is covered with a mud cake layer and the membrane pores are blocked during the continuous filtration process, resulting in contamination of the core membrane components, which is an important reason restricting the widespread promotion of anaerobic membrane separation devices. Food waste has a high organic matter content, and during the membrane filtration process, it often forms a membrane pore blockage dominated by organic pollution and secondary inorganic pollution, which will shorten the sustainable operation time of the membrane under high concentration operation.

[0004] The removal of membrane fouling (i.e., membrane cleaning) often requires stopping the operation of the anaerobic membrane separation device. Offline cleaning also requires disassembling the anaerobic membrane separation device, taking out the membrane and cleaning it separately with chemicals, which not only disturbs the anaerobic microorganisms and increases the recovery cycle of microbial activity, but also requires a large amount of chemicals, which increases the cost. Therefore, it is necessary to establish a suitable automatic online cleaning method, which can realize the transmembrane pressure difference identification and automatic chemical re-injection online cleaning through the controller, and realize the routine cleaning and maintenance of the membrane operation. It is a feasible method to maintain the long-term continuous operation of the anaerobic membrane separation device and extend the life of the membrane. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a kitchen waste membrane separation device and an automatic online membrane cleaning method, which controls the re-injection of cleaning liquid and aeration shaking through an automatic cleaning controller to improve the sustainability of membrane filtration and the economy of operation.

[0006] In order to solve the above technical problems, the technical solution provided by the present invention includes:

[0007] A food waste membrane separation device and an automatic online membrane cleaning method, the food waste membrane separation device mainly consists of a hollow fiber membrane, a feed pump, a gas collection bag, a constant temperature water bath layer, a filtration pump, a biogas circulation pump, a transmembrane pressure difference sensor, and an automatic cleaning controller. Among them, the hollow fiber membrane separation device is cylindrical, and a constant temperature water bath layer is provided outside the fermentation chamber, and the fermentation temperature in the fermentation chamber is maintained by constant temperature water circulation; the hollow fiber membrane is clamped in the fermentation chamber and placed hanging; the gas collection bag is placed in the head space of the device to collect biogas generated by fermentation; the biogas circulation pump is located on the biogas circulation pipeline, and is used to absorb biogas from the head space of the device and inject it from the bottom of the device, thereby shaking the membrane fibers; the feed pump is located on the side of the device to pump in food waste; the filtration pump is located on the membrane outlet pipeline, and is used to filtration the membrane outlet water, and a transmembrane pressure difference sensor is arranged between the membrane outlet and the filtration pump to monitor the filtration pressure. The automatic cleaning controller circuit is connected to the transmembrane pressure difference sensor, the filtration pump and the biogas circulation pump. The transmembrane pressure difference sensor records the filtration pressure data and sends it to the automatic cleaning controller. The automatic cleaning controller automatically controls the release of organic and inorganic pollutant removal agents to achieve automatic cleaning of the membrane separation device.

[0008] Preferably, the hollow fiber membrane is made of polyvinylidene fluoride or polytetrafluoroethylene or polyvinyl chloride, which is clamped in a cylindrical chamber with a constant temperature water bath layer and placed hanging. The membrane fibers have their own gravity bending angle, which can separate the membrane effluent from the solid matter in the anaerobic fermentation liquid, and can have a shaking function when the biogas circulation pump circulates the air.

[0009] Preferably, the food waste membrane separation device and the automatic online membrane cleaning method are characterized in that when membrane pollution occurs without online cleaning, the proportion of organic pollutants in the membrane pores is greater than 50%, the proportion of inorganic pollutants is less than 10%, and the main pollution category is organic pollution.

[0010] Preferably, the automatic cleaning controller obtains the cleaning agent reinjection control target value based on the transmembrane pressure difference sensor data in combination with a machine learning method, and can automatically issue a cleaning instruction.

[0011] Preferably, the filtration pump can extract membrane filtrate according to the forward rotation instruction issued by the automatic cleaning controller, and can also extract cleaning liquid according to the reverse rotation instruction issued by the automatic cleaning controller, thereby completing the automatic injection of the cleaning liquid.

[0012] Preferably, the biogas circulation pump circulates and extracts and injects the biogas generated by the food waste membrane separation device to realize biogas circulation control. When the automatic cleaning controller issues an automatic injection of cleaning liquid, the biogas circulation pump stops working; after the online cleaning is completed, the automatic cleaning controller can issue an intermittent aeration shaking instruction; when the automatic cleaning controller does not issue an automatic injection of cleaning liquid instruction, the biogas circulation pump performs biogas circulation according to the specified flux.

[0013] The biogas circulation pump receives the instruction of the automatic cleaning controller synchronously and has a linkage working function with the automatic cleaning controller.

[0014] The automatic online cleaning method described above uses an automatic cleaning controller to control the biogas circulation pump and the filter pump, and can issue instructions such as the cleaning time and the liquid injection speed. The steps include:

[0015] S1, when the transmembrane pressure difference sensor feedbacks that the filtration resistance increases to 2~3 times the initial operating value, the self-cleaning program is started;

[0016] S2, the automatic cleaning controller issues a cleaning command to the filter pump, and the filter pump reverses to inject volume V into the fiber membrane. 0 L cleaning agent, first inject sodium hypochlorite solution to remove organic pollution, after reinjection and mixing with the fermentation liquid in the reactor to form a total chloride ion concentration in the reactor in the range of 0.1~0.5g / L, the cleaning time is 15~20h, after the cleaning is completed, aeration is performed for 1~2h and V 0 L filtrate, sodium hypochlorite solution cleaning is completed;

[0017] S3, after the sodium hypochlorite cleaning solution is reinjected and cleaned, the filtration pump is reversed to inject volume V into the fiber membrane 0 L citric acid or oxalic acid solution is used to remove inorganic pollutants. After reinjection, it is mixed with the fermentation liquid in the reactor to form a total chloride ion concentration in the reactor in the range of 0.1~0.3 g / L. The cleaning time is 2~3 h. After the cleaning, it is aerated for 1~2 h and V 0 L filtrate, acid solution cleaning is completed;

[0018] S4, according to the feedback of the reinjection pressure from the transmembrane pressure difference sensor, the automatic cleaning controller automatically adjusts the filtration speed of the filtration pump to achieve adaptive injection; wherein, the reinjection amount of the cleaning agent described in S3 does not exceed one tenth of the volume of the fermentation liquid in the reactor;

[0019] According to the working status of the filtration pump, the biogas circulation pump is linked to perform biogas circulation to improve the removal efficiency of organic and inorganic pollutants;

[0020] S5, judging the cleaning effect by running the membrane filtration in a normal manner, if the transmembrane pressure difference sensor shows that the transmembrane pressure difference is less than 1.3 times of the initial state of operation, the automatic cleaning ends.

[0021] Compared with the prior art, the technical effects of the present invention are:

[0022] The present invention aims at removing membrane pollutants in the membrane treatment process of high-organic-content solid waste and kitchen waste, and realizes linkage cleaning of biogas circulation pump and suction filter pump by setting an automatic cleaning controller. Sodium hypochlorite is used to oxidize and remove organic pollutants, and citric acid is used to remove inorganic pollutants. The disturbance of membrane offline cleaning to the activity of anaerobic fermentation microorganisms can be reduced without introducing external oxygen and disassembling the anaerobic reactor. At the same time, the excessive accumulation of pollutants caused by long-term filtration can be reduced, the membrane permeability can be improved, and the continuous operation time can be extended, which is conducive to reducing the tedious work caused by membrane cleaning and improving the economic efficiency of the operation of the fiber membrane separation device. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the kitchen waste membrane separation device and the upper structure of the hollow fiber membrane;

[0024] Figure 2 Process workflow for automated membrane cleaning. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction 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 of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0026] To facilitate understanding of the embodiments of the present application, further explanation will be given below with reference to specific embodiments in conjunction with the accompanying drawings. The embodiments do not constitute a limitation on the embodiments of the present application.

[0027] Example

[0028] This embodiment discloses a restaurant waste membrane separation device and an automatic online membrane cleaning method, which uses a hollow fiber membrane treatment device made of polytetrafluoroethylene to perform anaerobic fermentation and membrane separation treatment on restaurant waste. The restaurant waste membrane separation device includes a hollow fiber membrane, a gas collection bag, a constant temperature water bath layer, a filtration pump, a biogas pump, a transmembrane pressure difference sensor, and an automatic cleaning controller, and continuously runs a filtration treatment experiment.

[0029] The effective volume of the kitchen waste membrane separation device is 3 L. On the membrane outlet pipe, a transmembrane pressure difference sensor is installed between the membrane outlet hole and the filtration pump to record and display the transmembrane pressure difference during the membrane filtration process. The automatic cleaning controller is set outside the device and connected to the transmembrane pressure difference sensor, filtration pump and biogas circulation pump.

[0030] The initial transmembrane pressure difference of the membrane operation is -3.0 kPa. After 10 days of operation, the transmembrane pressure difference reaches -6.0 kPa, which is twice the initial operation value. At this time, the automatic cleaning controller receives the transmembrane pressure difference sensor signal and starts the cleaning function.

[0031] The automatic cleaning controller controls the biogas circulation pump to stop working.

[0032] The automatic cleaning controller controls the filtration pump to reverse, and injects sodium hypochlorite from the membrane outlet pipe through the membrane outlet hole to the membrane filaments. The injection volume is 200 mL, and the injection time is 15 h. The injection pressure is within 5 kPa. The chloride ion concentration formed after injection is 0.3 g / L. The automatic cleaning controller controls the speed of the filtration pump to achieve adaptive control.

[0033] After the sodium hypochlorite reinjection is completed, the automatic cleaning controller controls the biogas circulation pump to start the biogas circulation flushing for 1 hour, and then the automatic cleaning controller controls the filtration pump to rotate forward, and 200 mL of membrane effluent is filtered out under the condition of biogas flushing.

[0034] The automatic cleaning controller controls the filtration pump to reverse, and injects citric acid from the membrane outlet pipe through the membrane outlet hole to the membrane filaments. The injection volume is 200 mL, and the injection time is 2 h. The injection pressure is within 5 kPa. The concentration of the acid solution formed after injection is 0.2 g / L. The automatic cleaning controller controls the speed of the filtration pump to achieve adaptive control.

[0035] After the reinjection of citric acid solution was completed, the automatic cleaning controller controlled the biogas circulation pump to start biogas circulation flushing for 1 h, and then the automatic cleaning controller controlled the filtration pump to rotate forward, and 200 mL of membrane effluent was filtered out under the condition of biogas flushing.

[0036] After the automatic cleaning is completed, the filtration process is carried out normally. The transmembrane pressure difference sensor shows that the filtration pressure is -3.2 kPa, which is 1.06 times that of the initial operation. The online cleaning is effective and the reactor can continue to operate.

[0037] Through the above method, the online cleaning method for removing membrane pollution of the kitchen waste membrane separation device in this embodiment can continuously complete the online cleaning of the membrane and make the membrane operate for a long time.

[0038] A food waste membrane separation device comprises a hollow fiber membrane, a constant temperature water bath layer, a filtration pump, a biogas circulation pump, a transmembrane pressure difference sensor, and an automatic cleaning controller; wherein the hollow fiber membrane separation device is cylindrical, and a constant temperature water bath layer is provided outside the fermentation chamber, and the fermentation temperature in the fermentation chamber is maintained by constant temperature water circulation; the hollow fiber membrane is clamped in the fermentation chamber and placed hanging; a gas collection bag is placed in the head space of the device to collect biogas generated by fermentation; the biogas circulation pump is located on the biogas circulation pipeline, and is used to absorb biogas from the head space of the device and inject it from the bottom of the device, thereby shaking the membrane fibers; the feed pump is located on the side of the device to pump in food waste; the filtration pump is located on the membrane outlet pipeline, and is used to filtrate the membrane outlet, and a transmembrane pressure difference sensor is provided between the membrane outlet and the filtration pump to monitor the filtration pressure in real time. The automatic cleaning controller circuit connects the transmembrane pressure difference sensor, the filtration pump, and the biogas circulation pump. The transmembrane pressure difference sensor records the filtration pressure data and sends it to the automatic cleaning controller. The automatic cleaning controller automatically controls the delivery of organic and inorganic pollutant removal agents to achieve automatic cleaning of the anaerobic membrane separation device. The hollow fiber membrane is made of polyvinylidene fluoride, polytetrafluoroethylene or polyvinyl chloride, and is clamped in a cylindrical chamber in a constant temperature water bath layer and placed in a hanging position. The membrane filament has its own gravity bending angle, which can separate the membrane effluent from the solid matter in the anaerobic fermentation liquid, and has a shaking function when the biogas circulation pump circulates air intake. The biogas circulation pump circulates and extracts and injects the biogas generated by the anaerobic membrane separation device for food waste to achieve biogas circulation control. When the automatic cleaning controller sends an automatic injection of cleaning liquid, the biogas circulation pump stops working. After the online cleaning is completed, the automatic cleaning controller can send an intermittent aeration shaking instruction. When the automatic cleaning controller does not send an automatic injection of cleaning liquid instruction, the biogas circulation pump performs biogas circulation according to the specified flux. The biogas circulation pump synchronously receives the instructions of the automatic cleaning controller and has a linkage working function with the automatic cleaning controller.

[0039] Preferably, the automatic cleaning controller obtains the cleaning agent reinjection control target value based on the data provided by the transmembrane pressure difference sensor in combination with a machine learning method, and automatically issues a cleaning instruction.

[0040] Preferably, the filtration pump extracts membrane filtrate according to a forward rotation instruction issued by the automatic cleaning controller, or extracts cleaning liquid according to a reverse rotation instruction issued by the automatic cleaning controller, thereby completing automatic injection of the cleaning liquid.

[0041] A method for automatically cleaning a membrane online of a kitchen waste membrane separation device is disclosed. The method controls a biogas circulation pump and a filter pump by an automatic cleaning controller, and issues instructions for cleaning time and liquid re-injection speed. The method comprises the following steps:

[0042] S1, when the transmembrane pressure difference sensor feedbacks that the filtration resistance increases to 2~3 times the initial value, self-cleaning is started;

[0043] S2, the automatic cleaning controller issues a cleaning command to the suction pump, and the suction pump reverses to inject a volume of V0 L of cleaning agent into the fiber membrane filaments. First, a sodium hypochlorite solution is injected to remove organic pollution. After reinjection, it is mixed with the fermentation liquid in the reactor to form a total chloride ion concentration in the reactor in the range of 0.1-0.5 g / L. The cleaning time is 15-20 h. After the cleaning is completed, aeration is performed for 1-2 h and V0 L of filtrate is filtered out, and the cleaning of the sodium hypochlorite solution is completed;

[0044] S3, after the sodium hypochlorite cleaning solution is reinjected and cleaned, the suction pump is reversed to inject V0 L of citric acid or oxalic acid solution into the fiber membrane to remove inorganic pollutants. After reinjection, the total chloride ion concentration in the reactor formed by mixing with the fermentation liquid in the reactor is in the range of 0.1-0.3 g / L. The cleaning time is 2-3 h. After the cleaning is completed, aeration is performed for 1-2 h and V0 L of filtrate is filtered out, and the acid solution cleaning is completed;

[0045] S4, according to the feedback of the reinjection pressure from the transmembrane pressure difference sensor, the automatic cleaning controller automatically adjusts the filtration speed of the suction pump to achieve adaptive injection; wherein, the reinjection amount of the cleaning agent described in S3 does not exceed one tenth of the volume of the fermentation liquid in the reactor; according to the operating status of the suction pump, the biogas circulation pump is linked to perform biogas circulation to improve the removal efficiency of organic and inorganic pollutants;

[0046] S5, judging the cleaning effect by running the membrane filtration in a normal manner, if the transmembrane pressure difference sensor shows that the transmembrane pressure difference is less than 1.3 times of the initial state of operation, the automatic cleaning ends.

[0047] The specific implementation methods described above further illustrate the purpose, technical solutions and beneficial effects of the present application in detail. It should be understood that the above description is only the specific implementation method of the present application and is not intended to limit the scope of protection of the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A kitchen waste membrane separation device, characterized in that: It includes a hollow fiber membrane, a constant temperature water bath layer, a filtration pump, a biogas circulation pump, a transmembrane pressure difference sensor, and an automatic cleaning controller; the hollow fiber membrane separation device is cylindrical, and a constant temperature water bath layer is outside the fermentation chamber, and the fermentation temperature in the fermentation chamber is maintained by constant temperature water circulation; the hollow fiber membrane is clamped in the fermentation chamber and placed hanging; a gas collection bag is placed at the top of the device to collect biogas produced by fermentation; The biogas circulation pump is located on the biogas circulation pipeline, and is used to absorb biogas from the top space of the device and inject it from the bottom of the device, thereby shaking the membrane fibers; the feed pump is located on the side of the device and is used to pump in food waste; the filtration pump is located on the membrane outlet pipeline, and is used to filter the water out of the membrane. At the same time, a transmembrane pressure difference sensor is arranged between the membrane outlet and the filtration pump to monitor the filtration pressure in real time; the automatic cleaning controller circuit connects the transmembrane pressure difference sensor, the filtration pump and the biogas circulation pump; the transmembrane pressure difference sensor records the filtration pressure data and sends it to the automatic cleaning controller, which automatically controls the delivery of organic and inorganic pollutant removal agents to realize automatic cleaning of the food waste membrane separation device; the hollow fiber membrane is made of polyvinylidene fluoride, polytetrafluoroethylene or polyvinyl chloride, and is clamped on the thermostat The membrane filaments are placed in a hanging position in a cylindrical chamber in the water bath layer, and have their own gravity bending angle, which can separate the membrane effluent from the solid matter in the anaerobic fermentation liquid, and have a shaking function when the biogas circulation pump circulates the air intake; the biogas circulation pump circulates and extracts and injects the biogas generated by the food waste membrane separation device to realize biogas circulation control; when the automatic cleaning controller sends an automatic injection of cleaning liquid, the biogas circulation pump stops working; after the online cleaning is completed, the automatic cleaning controller can send an intermittent aeration shaking instruction; when the automatic cleaning controller does not send an automatic injection of cleaning liquid instruction, the biogas circulation pump performs biogas circulation work according to the specified flux; the biogas circulation pump synchronously receives the instructions of the automatic cleaning controller, and has a linkage working function with the automatic cleaning controller.

2. A kitchen waste membrane separation device according to claim 1, characterized in that: The automatic cleaning controller obtains the cleaning agent reinjection control target value based on the data provided by the transmembrane pressure difference sensor in combination with a machine learning method, and automatically issues a cleaning instruction.

3. A kitchen waste membrane separation device according to claim 2, characterized in that: The filter pump extracts membrane filtrate according to the forward rotation instruction sent by the automatic cleaning controller, or extracts cleaning liquid according to the reverse rotation instruction sent by the automatic cleaning controller, thereby completing the automatic injection of the cleaning liquid.

4. An automatic online membrane cleaning method for a kitchen waste membrane separation device according to claim 3, characterized in that: The automatic online membrane cleaning method is implemented by an automatic cleaning controller to control the biogas circulation pump and the filter pump, and to issue instructions for the cleaning time and liquid injection speed; including step: S1, when the transmembrane pressure difference sensor feedbacks that the filtration resistance increases to 2~3 times the initial value, self-cleaning is started; S2, the automatic cleaning controller issues a cleaning command to the suction pump, and the suction pump reverses to inject a volume of V0 L of cleaning agent into the fiber membrane filaments. First, a sodium hypochlorite solution is injected to remove organic pollution. After reinjection, it is mixed with the fermentation liquid in the reactor to form a total chloride ion concentration in the reactor in the range of 0.1-0.5 g / L. The cleaning time is 15-20 h. After the cleaning is completed, aeration is performed for 1-2 h and V0 L of filtrate is filtered out, and the cleaning of the sodium hypochlorite solution is completed; S3, after the sodium hypochlorite cleaning solution is reinjected and cleaned, the suction pump is reversed to inject V0 L of citric acid or oxalic acid solution into the fiber membrane to remove inorganic pollutants. After reinjection, the total chloride ion concentration in the reactor formed by mixing with the fermentation liquid in the reactor is in the range of 0.1-0.3 g / L. The cleaning time is 2-3 h. After the cleaning is completed, aeration is performed for 1-2 h and V0 L of filtrate is filtered out, and the acid solution cleaning is completed; S4, according to the feedback of the reinjection pressure from the transmembrane pressure difference sensor, the automatic cleaning controller automatically adjusts the filtration speed of the suction pump to achieve adaptive injection; wherein, the reinjection amount of the cleaning agent described in S3 does not exceed one tenth of the volume of the fermentation liquid in the reactor; according to the operating status of the suction pump, the biogas circulation pump is linked to perform biogas circulation to improve the removal efficiency of organic and inorganic pollutants; S5, judging the cleaning effect by running the membrane filtration in a normal manner, if the transmembrane pressure difference sensor shows that the transmembrane pressure difference is less than 1.3 times of the initial state of operation, the automatic cleaning ends.

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