CN115231699A

CN115231699A - Anaerobic membrane bioreactor for wastewater treatment and wastewater treatment method thereof

Info

Publication number: CN115231699A
Application number: CN202210793698.1A
Authority: CN
Inventors: 周侃宇; 周金生; 葛玉龙
Original assignee: Jiangsu Peier Membrane Industry Co ltd
Current assignee: Jiangsu Peier Membrane Industry Co ltd
Priority date: 2022-07-05
Filing date: 2022-07-05
Publication date: 2022-10-25

Abstract

The invention discloses a wastewater treatment anaerobic membrane bioreactor and a wastewater treatment method thereof. Compared with the traditional anaerobic fermentation process, the anaerobic membrane bioreactor has the advantages of quick start, high pollutant removal rate, low sludge production amount, small occupied area, flexible operation and management and the like, so that the whole system not only has the advantages of economic investment saving, low energy consumption, technically recyclable biogas energy, high organic load, impact load resistance and the like. In addition, the method also has the characteristics of good biochemical effect and stable quality of produced water. The sludge mixture in the anaerobic effluent is not easy to attach to the surface of the membrane through methane back-aeration, so that the blockage and pollution to membrane pores are reduced, and the operation and maintenance cost of the treatment process is reduced.

Description

Anaerobic membrane bioreactor for wastewater treatment and wastewater treatment method thereof

Technical Field

The invention relates to the technical field of sewage treatment, in particular to an anaerobic membrane bioreactor for wastewater treatment.

Background

The biological treatment technology is a common method for wastewater treatment and is mainly divided into aerobic biological treatment and anaerobic biological treatment. The aerobic biological treatment effect is stable and reliable, but the aeration is needed, the energy consumption is large, and the aerobic biological treatment method is not suitable for treating high-concentration wastewater. Anaerobic biological treatment techniques have been widely used for the treatment of high-concentration wastewater due to their advantages of low energy consumption, low sludge production, and the ability to recover biogas during digestion. However, the existing anaerobic digestion process generally has the problems of slow growth of microorganisms, long start-up time, serious loss of anaerobic sludge, low pollutant removal efficiency and the like.

Therefore, the anaerobic membrane bioreactor, which is a novel device for treating sewage by combining anaerobic biotechnology and membrane separation technology, has attracted much attention in recent years. The technology has the advantages of high load and low energy consumption in anaerobic biological treatment, methane gas recovery and reutilization under anaerobic condition, and the like, and the membrane separation technology can realize the excellent characteristics of interception of suspended matters and microorganisms according to the size of the membrane aperture, and the like. Compared with the traditional sewage treatment process, the anaerobic membrane bioreactor has the advantages of good effluent quality, low residual sludge amount, energy recycling and the like. However, under anaerobic conditions, aeration of the membrane component cannot be performed, so that membrane pollution is aggravated, the cleaning frequency is increased, the service life of the membrane component is shortened, and the application of the anaerobic membrane bioreactor is severely restricted by the factor. Therefore, how to realize the high-efficiency aeration of the membrane component and relieve the membrane pollution is an important problem to be solved at present.

Disclosure of Invention

The invention aims to provide an anaerobic membrane bioreactor which can effectively inhibit membrane components from being polluted, prolong the service life and further improve the treatment efficiency.

In order to solve the technical problems, the invention provides the following technical scheme:

an anaerobic membrane bioreactor comprises an anaerobic tank and an MBR membrane pool, wastewater is conveyed to the anaerobic tank through a water inlet pump, effluent of the anaerobic tank automatically flows into the MBR membrane pool through an outlet valve at the top of the anaerobic tank,

a biogas backflow valve is arranged on the top of the anaerobic tank and connected with a biogas outlet valve on the top of the MBR membrane pool through a pipeline, so that biogas in the MBR membrane pool flows back; the MBR membrane tank is in anaerobic environment, a flat membrane component is arranged outside the MBR membrane tank, the flat membrane component is provided with a suction pump,

furthermore, an oxidation-reduction potentiometer, a pH meter, a temperature sensor and an electric heater are arranged on the anaerobic tank.

The oxidation-reduction potential is used for judging the oxygen content according to the ORP numerical value and preventing the destruction of an anaerobic environment, the pH meter is used for monitoring the pH value in the digestion process and preventing the system from being broken down due to acidification, the temperature sensor is linked with the electric heater to maintain the anaerobic digestion temperature, so that the anaerobic digestion is carried out in a medium-temperature environment, when the temperature of the temperature sensor is lower than 35 ℃, the electric heater is automatically started to start heating, and when the temperature is higher than 39 ℃, the electric heater is automatically closed to stop heating.

Furthermore, the bottom cloth of the anaerobic tank is provided with a water inlet arrangement pipeline, which aims to uniformly disperse the wastewater and prevent the phenomenon of overlarge local treatment load.

Further, a pressure gauge is arranged on the top of the anaerobic tank and used for monitoring the pressure in the tank and preventing overpressure;

furthermore, a biogas outlet valve and a biogas aeration valve are arranged at the top of the anaerobic tank, wherein the biogas outlet valve is connected with a wet gas flowmeter and is used for counting the biogas yield; the biogas aeration valve is connected with a biogas aeration fan through a pipeline.

The MBR membrane tank and the anaerobic tank are both in an anaerobic environment, and an external immersed flat membrane module is adopted, so that the installation is convenient and fast, and the cleaning and maintenance are easy.

The bottom of the MBR membrane tank is also provided with a water distribution pipeline, so that anaerobic effluent is uniformly distributed at the bottom of the tank. Biogas aeration pipelines are arranged at the bottoms of the anaerobic tank and the MBR membrane pool, wherein the biogas aeration pipelines are arranged in the anaerobic tank, digested sludge in the tank can be in a suspended state by utilizing the back aeration of biogas, so that wastewater can be fully contacted with microorganisms, the treatment efficiency is improved, meanwhile, soluble methane can be separated out, the methane content in the biogas is improved, and the aeration quantity can be adjusted by a flowmeter and a valve;

and a biogas aeration pipeline in the MBR membrane tank utilizes the return aeration biogas to wash the surface of the membrane, so that the formation of membrane pollution is relieved, and the aeration amount can be adjusted through a flowmeter and a valve.

Be equipped with the liquid level interlock in the MBR membrane cisterna, by the switch board control, when being in high liquid level in the MBR membrane cisterna, the suction pump can begin to operate, when being in low liquid level, the shutdown to the membrane pollution condition is judged to the installation negative pressure table.

Furthermore, the digested sludge intercepted in the membrane tank flows back to the anaerobic tank through the sludge reflux pump, so that the sludge concentration in the anaerobic tank is increased, and the treatment load is improved.

Furthermore, the aperture of the flat membrane component is 0.1-0.2 um.

The anaerobic environment of the anaerobic tank and the MBR membrane tank needs to control the oxidation-reduction potential to be in the range of-450 mV to-550 mV, the pH value is 7.2-7.5, the temperature is kept in a medium temperature environment (37 +/-2 ℃), when the temperature displayed by the temperature sensor is lower than 35 ℃, the heating device is started through interlocking of the control system, and when the temperature displayed is higher than 39 ℃, the heating is automatically stopped.

A wastewater treatment method of an anaerobic membrane bioreactor comprises the following specific steps:

the biochemical action of anaerobic microorganisms in the anaerobic reactor removes pollutants in the wastewater. The biochemical process mainly comprises three stages: firstly, in the hydrolysis acidification stage, the hydrolysis acidification bacteria degrade macromolecular organic matters in the wastewater into micromolecular substances, so that insoluble organic matters are converted into soluble organic matters, and the biodegradability of the wastewater is increased; secondly, in the hydrogen-producing and acetic acid-producing stage, organic matters are decomposed and converted into acetic acid and hydrogen under the action of hydrogen-producing and acetic acid-producing bacteria, so that organic matters are provided for the subsequent anaerobic digestion and methane production; and thirdly, in the stage of producing methane, acetic acid, carbon dioxide, hydrogen and the like are converted into methane by utilizing methanogenic bacteria. Although the anaerobic digestion process can be divided into the above stages, in the anaerobic reactor, the three stages are simultaneously carried out and are kept in dynamic equilibrium, and the influence factors are mainly temperature, pH, oxygen content, organic load and the like.

And S2) anaerobic effluent flows to an MBR membrane tank from the top automatically for membrane treatment. The flat membrane component is pumped by a suction pump, sludge taken away by anaerobic effluent is intercepted on the surface of the membrane, anaerobic environment in the pool is favorable for growth of methane bacteria, and the methane bacteria convert organic matters in the sewage into biological methane. Biogas in the anaerobic reactor and the membrane pool is collected to a biogas cabinet by pipelines, the biogas is pumped to the membrane pool by an air blower, and an aeration device is arranged at the bottom of the membrane pool to enable the biogas to uniformly scour the surface of the membrane, so that the backwashing of the membrane pool is realized, the formation of membrane pollution is inhibited, and the service life of the membrane component is prolonged. Meanwhile, the aeration quantity can be adjusted according to the change condition of the negative pressure meter, the aeration quantity is increased when the negative pressure is increased, and the aeration quantity is reduced when the negative pressure is reduced. Anaerobic sludge in the membrane tank can flow back to the anaerobic reactor through the sludge reflux pump, so that the sludge concentration of the reactor is improved.

The invention has the following beneficial effects:

the invention introduces a membrane component on the basis of the traditional anaerobic biological treatment technology, and can realize the complete separation of Sludge Retention Time (SRT) and hydraulic time (HRT) due to the interception effect of the membrane separation technology on microorganisms, thereby keeping the higher sludge concentration of the system. Therefore, compared with the traditional anaerobic fermentation process, the anaerobic membrane bioreactor has the advantages of quick start, high pollutant removal rate, low sludge production amount, small occupied area, flexible operation and management and the like, so that the whole system not only has the advantages of economic investment saving, low energy consumption, technically recyclable biogas energy, high organic load, impact load resistance and the like. In addition, the method also has the characteristics of good biochemical effect and stable quality of produced water. The sludge mixture in the anaerobic effluent is not easy to attach to the surface of the membrane through methane aeration, so that the blockage pollution to the membrane pores is reduced, and the operation and maintenance cost of the treatment process is reduced.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:

fig. 1 is a schematic structural view of the present invention.

Detailed Description

The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings, and it will be understood that they are described herein for the purpose of illustration and explanation and not limitation.

Examples

As shown in figure 1, the anaerobic membrane bioreactor is used for feeding waste water to an anaerobic tank 2 through a water inlet pump 1 for digestion treatment. The anaerobic tank 2 and the MBR membrane tank 3 are combined into an anaerobic membrane bioreactor for degrading pollutants in the wastewater. The inflow water passes through the anaerobic tank water distribution pipeline 8, so that the wastewater is uniformly dispersed at the bottom of the tank, and the phenomenon of overlarge local treatment load is prevented. An oxidation-reduction potentiometer 4 is arranged in the anaerobic tank 2, and the oxidation-reduction potential is controlled within the range of-450 mV to-550 mV, so that the anaerobic environment is prevented from being damaged; the pH meter 5 is used for monitoring the pH value in the digestion process, controlling the pH value to be between 7.2 and 7.5 and preventing the system from being broken down due to acidification; utilize temperature sensor 6 and heating device 7 to carry out the temperature interlocking, the required temperature condition of anaerobic digestion is controlled by switch board 24, for the microorganism grows and breeds good moderate temperature environment (37 +/-2 ℃), when temperature sensor 6 shows the temperature and is less than 35 ℃, start electric heating device 7 through switch board 24 interlocking, when the temperature shows to be higher than 39 ℃, the automatic shutdown heating, suitable temperature is favorable to little biological activity, improves the pollutant degradation rate. The anaerobic tank is provided with a pressure gauge 10 on the top for monitoring the pressure in the tank and preventing overpressure (> 5 kPa).

The methane reflux valve 9 is connected with a methane outlet valve 23 at the top of the MBR membrane pool 3 through a pipeline, so that the aerated methane in the membrane pool flows back to the anaerobic tank 2; the top of the anaerobic tank 2 is also provided with a biogas outlet valve 11 and a biogas aeration valve 13, wherein the biogas outlet valve 11 is connected with a wet gas flowmeter 12 and is used for counting the biogas yield; the biogas aeration valve 13 is connected with a biogas aeration fan 15 through a pipeline, a first biogas aeration pipeline 18 is arranged in the anaerobic tank 2, digested sludge in the tank can be in a suspended state by utilizing back aeration of biogas, wastewater can be fully contacted with microorganisms, the treatment efficiency is improved, meanwhile, soluble methane can be separated out, the methane content in the biogas is improved, and the aeration quantity can be adjusted through a first flow meter 17 and a first valve 16.

Anaerobic effluent automatically flows into the MBR membrane tank 3 through the outlet valve 14, and the MBR membrane tank and the anaerobic tank 2 are both in an anaerobic environment. The sludge brought away by anaerobic effluent is intercepted on the surface of the membrane by utilizing a membrane separation technology, and the anaerobic environment in the tank is favorable for the growth of methane bacteria, and the methane bacteria convert organic matters in the sewage into biological methane. The adopted external immersed membrane component 22 is convenient to install and easy to clean and maintain, and is an immersed membrane type flat membrane with the aperture of 0.1-0.2 um. A second biogas aeration pipeline 21 is arranged in the MBR membrane tank, the surface of the membrane is washed by the biogas subjected to back aeration to relieve the formation of membrane pollution, and the aeration amount can be adjusted by a second flowmeter 20 and a second valve 19. The membrane tank is internally provided with a liquid level interlock controlled by a control cabinet 24, when the MBR membrane tank 3 is at a high liquid level, the suction pump 26 starts to operate, and when the MBR membrane tank is at a low liquid level, the operation is stopped. The suction pump operates according to a mode of pumping for 8min and stopping for 2min, and the operation and stop time can be set by the controller. When the transmembrane pressure difference displayed by the negative pressure meter 25 under the same filtration flow rate of the membrane component is 35kPa higher than the transmembrane pressure difference in the initial stable operation, the membrane pollution condition is serious. The performance of the membrane can be recovered by a chemical cleaning mode, when the membrane pollution is mainly biological organic pollution, the membrane pollution is controlled by an alkali cleaning method, the used medicament is sodium hypochlorite, the concentration is 3000-5000mg/L, and the soaking time is 3-5 hours; when inorganic pollution is mainly caused, the method of acid washing is adopted for control, the common medicament is oxalic acid or citric acid, the concentration of the oxalic acid or the citric acid is 300-5000mg/L, and the soaking time is 3-5 hours. When cleaning, it is not necessary to mix sodium hypochlorite with oxalic acid or citric acid, which would generate toxic chlorine gas. The digested sludge intercepted in the membrane tank flows back to the anaerobic tank through the sludge return pump 27, so that the sludge concentration in the anaerobic tank is increased, and the treatment load is improved.

The invention not only can ensure that the reactor has the advantages of high pollutant removal rate, low sludge yield, high organic load, strong impact load resistance and the like, but also can ensure that the sludge mixture in anaerobic effluent is not easy to attach to the surface of the membrane in a methane aeration mode, reduce the blockage pollution of the sludge to membrane holes and further reduce the operation and maintenance cost of the treatment process.

Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An anaerobic membrane bioreactor comprises an anaerobic tank and an MBR membrane pool, wastewater is conveyed to the anaerobic tank through a water inlet pump, effluent of the anaerobic tank automatically flows into the MBR membrane pool through an outlet valve at the top of the anaerobic tank,

a biogas backflow valve is arranged on the top of the anaerobic tank and connected with a biogas outlet valve on the top of the MBR membrane pool through a pipeline, so that biogas in the MBR membrane pool flows back; the MBR membrane tank is in an anaerobic environment, a flat membrane component is arranged outside the MBR membrane tank, and a suction pump is arranged on the flat membrane component.

2. The anaerobic membrane bioreactor as claimed in claim 1, wherein the top of the anaerobic tank is further provided with a biogas outlet valve and a biogas aeration valve, wherein the biogas outlet valve is connected with a wet gas flowmeter for counting biogas output; the methane aeration valve is connected with a methane aeration fan through a pipeline.

3. The anaerobic membrane bioreactor as claimed in claim 1 or 2, wherein the bottom cloth of the anaerobic tank is provided with a water inlet arrangement line, the bottom of the MBR membrane tank is provided with a water distribution line, and a biogas aeration line, and aeration amount is adjusted by a flowmeter and a valve.

4. The anaerobic membrane bioreactor of claim 1, wherein the anaerobic tank is provided with a pressure gauge, an oxidation-reduction potentiometer, a pH meter, a temperature sensor and an electric heater.

5. The anaerobic membrane bioreactor of claim 1, wherein a liquid level interlock is arranged in the MBR membrane tank and is controlled by the control cabinet, when the liquid level in the MBR membrane tank is high, the suction pump starts to operate, and when the liquid level is low, the suction pump stops operating, and a negative pressure gauge is installed to judge the membrane pollution condition.

6. The anaerobic membrane bioreactor of claim 1, wherein the digested sludge intercepted in the MBR membrane tank is returned to the anaerobic tank by a sludge return pump.

7. An anaerobic membrane bioreactor as claimed in claim 1, wherein the pore size of the flat membrane module is 0.1-0.2 um.

8. A wastewater treatment method of an anaerobic membrane bioreactor is characterized in that:

the wastewater is pumped to an anaerobic tank through a water inlet pump for digestion treatment, the wastewater is uniformly dispersed at the bottom of the tank through a water distribution pipeline of the anaerobic tank, the redox potential in the anaerobic tank is controlled to be in the range of-450 to-550 mV, the pH is controlled to be 7.2 to 7.5, a temperature sensor and a heating device are utilized for temperature interlocking, the anaerobic digestion temperature is controlled to be 37 +/-2 ℃ by a control cabinet, and the pressure in the tank is less than or equal to 5kPa;

the aerated biogas in the MBR membrane tank flows back to the anaerobic tank; the top of the anaerobic tank is also provided with a biogas outlet valve and a biogas aeration valve, the biogas aeration valve is connected with a biogas aeration fan through a pipeline, a first biogas aeration pipeline is arranged in the anaerobic tank, digested sludge in the tank is in a suspended state by utilizing return aeration of biogas, wastewater is fully contacted with microorganisms, meanwhile, soluble methane can be separated out, the content of methane in the biogas is improved, and the aeration amount can be adjusted through a first flowmeter and a first valve;

anaerobic effluent automatically flows into an MBR membrane tank through an outlet valve, and the MBR membrane tank and the anaerobic tank are both in an anaerobic environment; intercepting sludge taken away by anaerobic effluent on the surface of a membrane by utilizing a membrane separation technology, wherein an external immersed membrane component adopted by an MBR membrane tank is an immersed membrane type flat membrane, and the aperture of the external immersed membrane component is 0.1-0.2 um; a second biogas aeration pipeline 21 is arranged in the MBR membrane tank, the surface of the membrane is washed by the back-aerated biogas to relieve the formation of membrane pollution, and the aeration amount can be adjusted by a second flowmeter and a second valve;

a liquid level interlock is arranged in the MBR membrane tank and is controlled by a control cabinet 24, when the MBR membrane tank is at a high liquid level, the suction pump can start to operate, and when the MBR membrane tank is at a low liquid level, the operation is stopped;

the operation and stop time of the suction pump can be set by the controller, and when the transmembrane pressure difference displayed by the negative pressure gauge of the membrane component under the same filtration flow is 35kPa higher than the transmembrane pressure difference during initial stable operation, the membrane performance can be recovered by a chemical cleaning mode;

the digested sludge intercepted in the membrane tank flows back to the anaerobic tank through the sludge reflux pump, so that the sludge concentration in the anaerobic tank is increased, and the treatment load is improved.

9. The wastewater treatment method of the anaerobic membrane bioreactor as claimed in claim 8, characterized in that when the membrane pollution of the MBR membrane tank is mainly biological organic pollution, the control is carried out by adopting an alkali washing method, the used medicament is sodium hypochlorite, the concentration is 3000-5000mg/L, and the soaking time is 3-5 hours; when inorganic pollution is mainly caused, the method of acid washing is adopted for control, the common medicament is oxalic acid or citric acid, the concentration of the oxalic acid or the citric acid is 300-5000mg/L, and the soaking time is 3-5 hours.