Photosynthetic bacteria membrane electrobiological reaction device based on conductive material and dairy product wastewater treatment method

Abstract

The invention discloses a photosynthetic bacterium membrane electrobiological reaction device based on a conductive material and a dairy product wastewater treatment method, and aims to solve the technical problems of poor dairy product wastewater treatment effect, difficulty in photosynthetic bacterium resource utilization, serious membrane pollution and the like. The photosynthetic bacteria membrane electrobiological reaction device comprises a reaction container communicated with the wastewater storage container, a cathode conducting membrane assembly arranged in the reaction container and used for discharging water and intercepting photosynthetic bacteria, and an anode titanium mesh arranged in the reaction container and used for constructing an electric field; the direct-current stabilized power supply is arranged outside the reaction container and used for providing voltage for the cathode conducting film assembly and the anode titanium mesh, and the incandescent lamp is used for providing illumination for the reaction container. According to the application, the pollutant removal capability of the photosynthetic bacteria is improved under the action of the electric field, meanwhile, the membrane pollution is slowed down to a great extent, and when the application is applied to dairy product wastewater treatment, the synergistic target of pollution reduction and carbon reduction of wastewater treatment can be achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial wastewater treatment, and specifically to a photosynthetic bacteria membrane electrobiological reaction device based on conductive materials and a method for treating dairy wastewater. Background Art

[0002] Dairy wastewater is a typical food processing wastewater. The main pollutants in dairy wastewater are milk protein, milk fat, lactose and minerals contained in raw milk, acidic and alkaline detergents used to clean production equipment, pipes, containers and workshop floors. cr The concentration is about 1500-2500 mg / L, biological oxygen demand BOD 5 The concentration is about 800-1500 mg / L, the suspended solids SS concentration is about 200-400 mg / L, the oil concentration is about 150-300 mg / L, the total nitrogen TN concentration is about 30-50 mg / L, the total phosphorus TP concentration is about 5-15 mg / L, and the pH value is about 5-7. Generally speaking, the wastewater produced by producing 1 ton of dairy products can reach 30-35 m3 / L. 3 For dairy companies with better management levels, the wastewater discharge volume is 1 to 3 times the dairy processing volume.

[0003] Since the BOD and COD values ​​in dairy wastewater are both high and the biodegradability is good (BOD / COD is generally above 0.5), biochemical treatment is generally used as the core unit for dairy wastewater treatment. Traditional dairy wastewater is divided into three stages of treatment: pretreatment (coarse and fine screens, coagulation and sedimentation, flotation, etc.), anaerobic biochemical treatment (hydrolysis acidification, UASB, ABR, etc.) and aerobic biochemical treatment (activated sludge method, SBR, biofilm method, etc.). Pretreatment removes fine particles and emulsified substances such as oil and suspended matter in the wastewater. Secondly, anaerobic biochemical treatment degrades large molecular organic matter in the wastewater into small molecular organic matter. Finally, aerobic biological treatment degrades most of the organic matter in the wastewater into CO 2 and H 2 O, in order to meet emission standards.

[0004] The inventors know a method for treating dairy wastewater using non-oxygen-producing photosynthetic bacteria. Non-oxygen-producing photosynthetic bacteria can treat dairy wastewater under anaerobic conditions of light, not only efficiently treating organic pollutants, but also assimilating nutrients in wastewater into their own cell substances. Photosynthetic bacteria are rich in single-cell proteins, coenzyme Q 10 , polyhydroxyalkanoates, 5-aminolevulinic acid, carotenoids and other high-value substances can be used in many industries such as aquaculture, health care and crop production. Since the natural sedimentation of non-oxygenous photosynthetic bacterial cells is difficult, their suspended growth state makes the cells easy to lose and the solid-liquid separation difficult.

[0005] The information disclosed in this background technology section is only used to deepen the understanding of the background technology of the present disclosure, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art known to those skilled in the art. Summary of the invention

[0006] The inventors have found through research that photosynthetic bacteria can effectively remove organic matter as well as nitrogen, phosphorus and sulfide in wastewater. However, there are problems such as difficulty in degrading macromolecular substances, easy loss of bacteria and difficulty in solid-liquid separation during the treatment of wastewater using photosynthetic bacteria.

[0007] In view of at least one of the above technical problems, the present disclosure provides a photosynthetic bacteria membrane electrobioreactor device based on conductive materials and a dairy wastewater treatment method, which can improve the ability of photosynthetic bacteria to remove pollutants through the action of the electric field, while greatly reducing membrane pollution, thereby achieving synergistic efficiency in wastewater treatment to reduce pollution and carbon emissions.

[0008] According to one aspect of the present disclosure, a photosynthetic bacteria membrane electrobiological reaction device based on conductive materials is provided, comprising a reaction container connected to a wastewater storage container, a cathode conductive film assembly arranged in the reaction container for discharging water and intercepting photosynthetic bacteria, an anode titanium mesh arranged in the reaction container for constructing an electric field, a DC regulated power supply arranged outside the reaction container for providing voltage to the cathode conductive film assembly and the anode titanium mesh, and a light source for providing light to the reaction container.

[0009] In some embodiments of the present disclosure, the cathode conductive membrane assembly includes a hollow fiber ultrafiltration membrane that has been subjected to the following chemical surface modification treatment: the hollow fiber ultrafiltration membrane is treated with alkali and then immersed in a saturated sodium bisulfite solution for 10 to 14 hours, and then immersed in a 0.5 g / L GO dispersion for 2 to 4 hours to obtain a GO / PVDF hollow fiber ultrafiltration membrane.

[0010] In some embodiments of the present disclosure, the reaction container is made of colorless and transparent organic glass; the light source (such as an incandescent lamp) is arranged around the outer side of the wall of the reaction container.

[0011] In some embodiments of the present disclosure, the reaction container is inoculated with Rhodopseudomonas palustris, Rhodopseudomonas colloids, Rhodopseudomonas capsulatus, etc., and the inoculation amount under initial conditions is 800-1200 mg / L.

[0012] In some embodiments of the present disclosure, the photosynthetic bacteria membrane electrobiological reaction device further includes a backwashing device for backwashing the cathode conductive membrane assembly, and the backwashing device includes a corresponding connected backwashing pipeline and a corresponding backwashing pump.

[0013] In some embodiments of the present disclosure, the photosynthetic bacteria membrane electrobiological reaction device also includes a liquid level sensor for monitoring the water level in the reaction container and a signal line for controlling the water inlet valve to ensure the normal operation of the device; the incandescent lamp, DC regulated power supply, liquid level sensor and water inlet valve are all electrically connected to the corresponding circuit system through their own adapted circuit connection methods.

[0014] In some embodiments of the present disclosure, sampling ports with different liquid levels are provided on the wall of the reaction container from top to bottom, an overflow port is provided on the top of the reaction container, and corresponding water inlets and drain ports are provided on the bottom.

[0015] According to another aspect of the present disclosure, a method for treating dairy wastewater is provided, which is implemented based on the above-mentioned photosynthetic bacteria membrane electrobiological reaction device, and comprises the following steps: (1) Pre-treat the dairy wastewater to be treated; (2) starting the photosynthetic bacteria membrane electrobiological reaction device, introducing the dairy wastewater pretreated in the previous step into the reaction container from the bottom, and allowing the wastewater to flow out of the reaction container through the cathode conductive membrane assembly located at the top of the reaction container; (3) Detecting the effluent quality and the biomass in the reaction vessel to ensure that the discharge meets the standards.

[0016] In some embodiments of the present disclosure, in step (2), the biomass concentration in the reaction container is controlled to be 2000-3000 mg / L, the light intensity is 2000-4000 lux, the light-dark cycle is 16 h light / 8 h dark or 24 h light / 0 h dark, the operating water temperature is 15-25°C, the pH value is 6.5-7.5, the dissolved oxygen concentration is 0-0.5 mg / L, the hydraulic retention time is 48-72 h, and the flux of the original PVDF membrane is 10-15 L / (m 2 ·h) Operating pressure is 10~40kPa.

[0017] In some embodiments of the present disclosure, the electric field strength applied to the cathode conductive film assembly is 0.4 V / cm to 1.2 V / cm.

[0018] One or more technical solutions provided in the embodiments of the present application have at least any of the following technical effects or advantages: 1. This application effectively solves the technical problems of easy loss of non-oxygen photosynthetic bacteria in the reaction vessel and difficulty in resource utilization by introducing the cathode conductive film component into the reaction vessel, thereby realizing the efficient separation of photosynthetic bacteria and wastewater; and after the cathode conductive film component of this application is chemically surface modified, the membrane flux, hydrophilicity and anti-pollution performance are enhanced, and it can be combined with the electric field to effectively degrade pollutants.

[0019] 2. Compared with the traditional process, the power consumption of the device in this application is relatively low. At the same time, biomass can be separated from the reaction vessel to achieve the recovery and extraction of high-value substances, thereby achieving the goals of "energy saving, consumption reduction, pollution reduction, and efficiency improvement".

[0020] 3. The photosynthetic bacteria membrane electrobiological reaction device in this application uses a titanium mesh as an anode and a modified conductive membrane as a cathode to form an electric field in a photosynthetic bacteria membrane reaction vessel. First, through the electrochemical oxidation of the anode, complex and difficult-to-degrade organic matter is decomposed into small molecules that are easily degradable organic matter, thereby improving the efficiency of photosynthetic bacteria in degrading organic matter; second, compared with the original unmodified membrane, the modified conductive membrane has a higher water flux, better hydrophilicity and stronger anti-pollution performance; finally, a negative potential is applied to the modified conductive membrane. Since pollutants and microorganisms usually carry a negative charge, they will be repelled by the negative charge on the surface of the conductive membrane, and the adhesion and deposition of pollutants to the membrane surface are reduced under the action of electrostatic repulsion.

[0021] 4. The anaerobic microorganisms represented by the introduction of the dominant non-oxygen-producing photosynthetic bacteria (such as Rhodopseudomonas palustris, Rhodopseudomonas colloids, Rhodopseudomonas capsulatus, etc.) into the photosynthetic bacteria membrane reaction vessel can utilize photosynthetic bacteria to assimilate the nutrients in the dairy wastewater into their own cell substances, effectively degrade pollutants while realizing the self-proliferation of the bacteria, so as to achieve the purpose of pollutant removal and high-value substance production. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic structural diagram of a photosynthetic bacteria membrane electrobiological reaction device based on conductive materials in one embodiment of the present application.

[0023] Figure 2 The figure shows the change of TMP value during the operation of the reaction container under different electric field strengths in one embodiment of the present application.

[0024] Figure 3 This is a diagram of biomass concentration in a reaction container treating simulated dairy wastewater under different electric field strengths in an embodiment of the present application.

[0025] Figure 4 This is a diagram of the main effluent indicators of a reaction container treating simulated dairy wastewater under different electric field intensities in one embodiment of the present application.

[0026] In the above figures, 1 is a wastewater storage container, 2 is a water inlet pipeline, 21 is a water inlet pump, 22 is a water inlet valve, 23 is a water inlet, 3 is an anode titanium mesh, 4 is a sampling port, 5 is a reaction container, 51 is a cathode conductive film assembly, 52 is an electrode clamp, 6 is a DC regulated power supply, 7 is a water outlet pipeline, 71 is a water outlet valve, 72 is a vacuum pressure gauge, 73 is a suction pump, 74 is a water outlet, 8 is a backwash pipeline, 81 is a backwash valve, 82 is a backwash pump, and 9 is an incandescent lamp. DETAILED DESCRIPTION

[0027] In order to better understand the technical solution of the present application, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0028] Example 1 In order to solve the technical problems of substandard effluent quality when using non-oxygen-producing photosynthetic bacteria to treat dairy wastewater, easy loss of bacteria due to poor sedimentation of photosynthetic bacteria and difficulty in resource utilization, and serious membrane pollution caused by the use of membrane components, this example discloses a photosynthetic bacteria membrane electrobiological reaction device based on conductive materials, see Figure 1 , including a reaction container 5 connected to a wastewater storage container 1, a cathode conductive film assembly 51 arranged in the reaction container 5 for discharging water and intercepting photosynthetic bacteria, an anode titanium mesh 3 arranged in the reaction container 5 for constructing an electric field, a DC regulated power supply 6 arranged outside the reaction container 5 for providing voltage to the cathode conductive film assembly 51 and the anode titanium mesh 3, and an incandescent lamp 9 for providing light to the reaction container 5.

[0029] Specifically, the cathode conductive membrane assembly 51 is a hollow fiber ultrafiltration membrane made of PVDF (polyvinylidene fluoride), with a membrane pore size of 0.02 μm and a membrane effective area of ​​150 cm 2 . Hollow fiber ultrafiltration membrane with chemical surface modification of cathode conductive membrane assembly 51: After alkali treatment, the hollow fiber ultrafiltration membrane is soaked in a saturated sodium bisulfite solution for 10 to 14 hours, and then soaked in a 0.5g / L GO dispersion for 2 to 4 hours to obtain a GO / PVDF hollow fiber ultrafiltration membrane, which has improved hydrophilicity and enhanced anti-pollution ability of the modified membrane. The size of the anode titanium mesh 3 surrounding the cathode conductive membrane assembly 51 is 18.8cm×8cm, and the output voltage of the DC regulated power supply 6 is 0 to 1.2V, and the degradation of membrane pollution is achieved under the action of voltage.

[0030] Specifically, the reaction container 5 is made of colorless and transparent organic glass; the incandescent lamp 9 is arranged around the outer side of the wall of the reaction container 5; the reaction container 5 is inoculated with palustrine Rhodopseudomonas, colloid Rhodopseudomonas, capsule Rhodopseudomonas, etc., and the inoculation amount under initial conditions is 800~1200 mg / L; it also includes a backwashing device for backwashing the cathode conductive membrane assembly 51, and the backwashing device includes a corresponding connected backwashing pipeline 8 and a corresponding backwashing pump 82; it also includes a liquid level sensor for monitoring the water level in the reaction container 5 and a signal line for controlling the water inlet valve 22 to ensure the normal operation of the device; the incandescent lamp 9, the DC regulated power supply 6, the liquid level sensor and the water inlet valve 22 are all electrically connected to the corresponding circuit system through their own adaptive circuit connection methods; sampling ports 4 with different liquid levels are arranged from top to bottom on the wall of the reaction container 5, an overflow port is arranged at the top of the reaction container 5, and corresponding water inlets and drain ports are arranged at the bottom.

[0031] In this embodiment, a water inlet pipeline 2 is provided between the reaction container 5 and the wastewater storage container 1, and the dairy wastewater to be treated is transported to the reaction container 5 via the water inlet pipeline 2. A section of the water inlet pipeline 2 is connected with a water inlet pump 21 and a water inlet valve 22, which are used to lift the dairy wastewater in the wastewater storage container 1 into the reaction container 5. In this embodiment, the water inlet 23 is provided at the bottom of the reaction container 5 close to the wall, and the reaction container 5 is equipped with a liquid level sensor to ensure the working liquid level in the reaction container 5 and the normal operation of the device. The water inlet pipeline 2 is connected to a flow meter and a water inlet valve in sequence along the water inlet direction, and the water volume of the reaction container 5 is monitored and controlled through the flow meter and the water inlet valve.

[0032] Specifically, the cathode conductive membrane assembly 51, the water outlet pipeline 7, the water outlet valve 71, the vacuum pressure gauge 72, and the suction pump 73 are connected in sequence between the water outlet 74 and the reaction container 5. The dairy wastewater treated by the reaction container 5 is discharged to the water outlet 74 via the water outlet pipeline 7; the suction pump 73 sucks the treated dairy wastewater into the water outlet pipeline 7 through the cathode conductive membrane assembly 51, passes through the water outlet valve 71, the vacuum pressure gauge 72, the suction pump 73 and the flow meter in sequence, and is finally sent to the water outlet 74 by the suction pump 73; in this embodiment, the flow rate of the water outlet pipeline 7 is controlled by the water outlet valve 71, the transmembrane pressure of the cathode conductive membrane assembly 51 is monitored by the vacuum pressure gauge 72, and the outlet water flow rate is monitored by the flow meter.

[0033] Specifically, the cathode conductive membrane assembly 51 is provided with a membrane backwashing pipeline 8, one end of which is connected to the cathode conductive membrane assembly 51, and the other end is sequentially connected to a backwashing valve 81 and a backwashing pump 82. When a serious membrane contamination problem (TMP ≥ 40 kPa) occurs in the cathode conductive membrane assembly 51, the outlet valve 71 and the suction pump 73 of the outlet pipeline 7 are closed, the backwashing pump 82 is started, and the backwashing valve 81 is opened, and water flows through the backwashing pump 82 to the cathode conductive membrane assembly 51, thereby backwashing the cathode conductive membrane assembly 51.

[0034] In this embodiment, a method for treating dairy wastewater using a photosynthetic bacteria membrane electrobiological reaction device based on a conductive material is also disclosed, which specifically includes the following steps: (1) In this embodiment, synthetic dairy wastewater is used as the test water source, and the main water quality indicators of the simulated wastewater are shown in Table 1. In order to balance the amount of water entering the reaction container, a liquid level sensor is used to control the water inlet.

[0035] Table 1 Main water quality indicators of simulated dairy wastewater (unit: mg / L) .

[0036] (2) Control the initial conditions of the reaction vessel: biomass concentration of 1000 mg / L, operating water temperature of 15-25 °C, pH value of 6.5-7.5, dissolved oxygen concentration of 0-0.5 mg / L, electric field strength of 0.4 V / cm, light intensity of 3500-4000 lux, light-dark cycle of 16 h light / 8 h dark or 24 h light / 0 h dark, hydraulic retention time of 72 h, and operating pressure of 10-40 kPa.

[0037] (3) Detect the biomass, effluent quality and membrane pollution of the reaction vessel: measure the biomass in the reaction vessel every 24 hours and measure the COD in the wastewater every 48 hours. cr concentration, TN concentration, NH 3 -N concentration, TP concentration, the reading of the vacuum pressure gauge is measured every 24 hours, and the membrane pollution situation is directly reflected by the vacuum pressure gauge connected to the outlet pipe. When the value of the vacuum pressure gauge reaches 40kPa, the cathode conductive membrane assembly is backwashed.

[0038] Example 2 In this embodiment, except that the electric field intensity is 0.8 V / cm, the arrangement and operation method of the photosynthetic bacteria membrane electrobiological reaction device are the same as those in Embodiment 1.

[0039] Example 3 In this embodiment, except that the electric field intensity is 1.2 V / cm, the arrangement and operation method of the photosynthetic bacteria membrane electrobiological reaction device are the same as those in Embodiment 1.

[0040] The biomass changes of the photosynthetic bacteria membrane electrobiological reactor in Examples 1-3 under different electric field strengths when treating sewage were detected, and the electric field strength was 0 V / cm, and the settings and operation methods of other photosynthetic bacteria membrane electrobiological reactors were the same as those in Example 1 as a comparative example. The biomass of photosynthetic bacteria before and after the operation of the device under different electric field strengths was detected, and the changes in the biomass concentration of photosynthetic bacteria are shown in Table 2. Under the condition of an electric field strength of 0.8 V / cm, the biomass concentration of the reactor was the highest.

[0041] Table 2 Changes in biomass of photosynthetic bacteria reaction device under different electric field intensities (unit: g / L) .

[0042] The main water quality indicators of dairy wastewater before and after treatment by the reaction device were tested, and the treatment effects of the main water quality indicators of the wastewater are shown in Table 3. The photosynthetic bacteria in the reaction device can use the organic matter in the dairy wastewater to synthesize its own cell substances through metabolism and assimilation under the condition of light anaerobic, so as to achieve the purpose of removing pollutants in the wastewater. The wastewater treated by the reaction device basically meets the indirect discharge standard of the water pollutant discharge concentration limit of new enterprises in the "Starch Industry Water Pollutant Discharge Standard" (GB 25461-2010), and can be directly discharged after subsequent treatment.

[0043] Table 3 Wastewater effluent quality and its optimal treatment effect (0.8V / cm) .

[0044] From Tables 2 and 3, Figures 2 to 4 It can be seen that after the dairy wastewater is treated by the reaction device, the COD cr TN, NH 3 -N and TP concentrations were significantly reduced, and the membrane pollution of the cathode conductive membrane assembly was reduced, which proved that the reaction vessel of the device can achieve efficient treatment of dairy wastewater. At the same time, the overall energy consumption of the device is low and the economic benefits are good.

[0045] Although some preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present application.

[0046] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the inventive concept. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A photosynthetic bacteria membrane electrobiological reaction device based on conductive materials, comprising a reaction container connected to a wastewater storage container, It is characterized in that It also includes a cathode conductive film assembly arranged in the reaction container for discharging water and intercepting photosynthetic bacteria, an anode titanium mesh arranged in the reaction container for constructing an electric field, a DC regulated power supply arranged outside the reaction container for providing voltage to the cathode conductive film assembly and the anode titanium mesh, and a light source for providing light to the reaction container.

2. The photosynthetic bacteria membrane electrobiological reaction device according to claim 1, It is characterized in that The cathode conductive membrane assembly comprises a hollow fiber ultrafiltration membrane treated with the following chemical surface modification: After the hollow fiber ultrafiltration membrane was treated with alkali, it was immersed in a saturated sodium bisulfite solution for 10-14 h, and then immersed in a 0.5 g / L GO dispersion for 2-4 h to obtain a GO / PVDF hollow fiber ultrafiltration membrane.

3. The photosynthetic bacteria membrane electrobiological reaction device according to claim 1, It is characterized in that The reaction container is made of colorless and transparent organic glass; the light source is arranged around the outer side of the wall of the reaction container.

4. The photosynthetic bacteria membrane electrobiological reaction device according to claim 1, It is characterized in that The reaction container is inoculated with Rhodopseudomonas palustris, Rhodopseudomonas colloids, Rhodopseudomonas capsules, etc., and the inoculation amount under initial conditions is 800-1200 mg / L.

5. The photosynthetic bacteria membrane electrobiological reaction device according to claim 1, It is characterized in that It also includes a backwashing device for backwashing the cathode conductive membrane assembly, and the backwashing device includes a corresponding connected backwashing pipeline and a corresponding backwashing pump.

6. The photosynthetic bacteria membrane electrobiological reaction device according to claim 1, It is characterized in that It also includes a liquid level sensor for monitoring the water level in the reaction container and a signal line for controlling the water inlet valve to ensure the normal operation of the device; the light source, DC regulated power supply, liquid level sensor and water inlet valve are all electrically connected to the corresponding circuit system through their own adapted circuit connection methods.

7. The photosynthetic bacteria membrane electrobiological reaction device according to claim 1, It is characterized in that Sampling ports with different liquid levels are arranged from top to bottom on the wall of the reaction container, an overflow port is arranged at the top of the reaction container, and corresponding water inlets and drain ports are arranged at the bottom.

8. A method for treating dairy wastewater, It is characterized in that The method is implemented based on the photosynthetic bacteria membrane electrobiological reaction device according to claim 1, comprising the following steps: (1) Pre-treat the dairy wastewater to be treated; (2) starting the photosynthetic bacteria membrane electrobiological reaction device, introducing the dairy wastewater pretreated in the previous step into the reaction container from the bottom, and allowing the wastewater to flow out of the reaction container through the cathode conductive membrane assembly located at the top of the reaction container; (3) Detecting the effluent quality and the biomass in the reaction vessel to ensure that the discharge meets the standards.

9. The method for treating dairy wastewater according to claim 8, It is characterized in that In the step (2), the biomass concentration in the reaction container is controlled to be 2000-3000 mg / L, the light intensity is 2000-4000 lux, the light-dark cycle is 16 h light / 8 h dark or 24 h light / 0 h dark, the operating water temperature is 15-25°C, the pH value is 6.5-7.5, the dissolved oxygen concentration is 0-0.5 mg / L, the hydraulic retention time is 48-72 h, and the flux of the original PVDF membrane is 10-15 L / (m 2 ·h) Operating pressure is 10~40kPa.

10. The method for treating dairy wastewater according to claim 8, It is characterized in that The electric field strength applied to the cathode conductive film assembly is 0.4V / cm to 1.2V / cm.

Images